Name: assessing cellular stress and inflammation in discrete oxytocin-secreting brain nuclei in the neonatal rat before and after first colostrum feeding
Uploaded: 2018-11-14T14:15:00
Description: Watch this Scientific Journal Video about Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding at JoVE.co

The authors thank Manon Ranger and Alexandra Schulz for their assistance in preparing this protocol.

This study was approved by the Institutional Animal Care and Use Committees at Columbia University and the New York State Psychiatric Institute.
1. Tissue Preparation
<ol>
	<li>Order timed pregnant rats from vendor.</li>
	<li>Follow timed pregnant rats by observing their growing abdomens in the weeks after their arrival and subsequently looking for pups on the expected delivery date by inspecting the cage every 2 h until delivery begins.</li>
	<li>Remove pups with a gloved hand by their tail...

<ol>
	<li>Hietaniemi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression+profiles+in+fetal+and+neonatal+rat+offspring+of+energy-restricted+dams.">Gene expression profiles in fetal and neonatal rat offspring of energy-restricted dams.</a> Journal of Nutrigenetics and Nutrigenomics. 2 (4-5), 173-183 (2009).</li><li>Okabe, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homogenous+glycine+receptor+expression+in+cortical+plate+neurons+and+Cajal-Retzius+cells+of+neonatal+rat+cerebral+cortex.">Homogenous glycine receptor expression in cortical plate neurons and Cajal-Retzius cells of neonatal rat cerebral cortex.</a> Neuroscience. 123 (3), 715-724 (2004).</li><li>Mailleux, P., Takazawa, K., Erneux, C., Vanderhaeghen, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+of+the+neurons+containing+inositol+1,4,5-trisphosphate+3-kinase+and+its+messenger+RNA+in+the+developing+rat+brain.">Distribution of the neurons containing inositol 1,4,5-trisphosphate 3-kinase and its messenger RNA in the developing rat brain.</a> Journal of Comparative Neurology. 327 (4), 618-629 (1993).</li><li>Carter, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+and+Human+Evolution.">Oxytocin and Human Evolution.</a> Current Topics in Behavioral Neuroscience. , (2017).</li><li>Sippel, L. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+and+Stress-related+Disorders:+Neurobiological+Mechanisms+and+Treatment+Opportunities.">Oxytocin and Stress-related Disorders: Neurobiological Mechanisms and Treatment Opportunities.</a> Chronic Stress (Thousand Oaks). 1, (2017).</li><li>Agnati, L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aspects+on+the+integrative+actions+of+the+brain+from+neural+networks+to+"brain-body+medicine".">Aspects on the integrative actions of the brain from neural networks to "brain-body medicine".</a> Journal of Receptors and Signal Transduction Research. 32 (4), 163-180 (2012).</li><li>Welch, M. G., Margolis, K. G., Li, Z., Gershon, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+regulates+gastrointestinal+motility,+inflammation,+macromolecular+permeability,+and+mucosal+maintenance+in+mice.">Oxytocin regulates gastrointestinal motility, inflammation, macromolecular permeability, and mucosal maintenance in mice.</a> American Journal Physiology: Gastrointestinal and Liver Physiology. 307 (8), G848-G862 (2014).</li><li>Welch, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+and+developmental+regulation+of+oxytocin+(OT)+and+oxytocin+receptors+(OTR)+in+the+enteric+nervous+system+(ENS)+and+intestinal+epithelium.">Expression and developmental regulation of oxytocin (OT) and oxytocin receptors (OTR) in the enteric nervous system (ENS) and intestinal epithelium.</a> Journal of Comparative Neurology. 512 (2), 256-270 (2009).</li><li>Prakash, B. S., Paul, V., Kliem, H., Kulozik, U., Meyer, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+oxytocin+in+milk+of+cows+administered+oxytocin.">Determination of oxytocin in milk of cows administered oxytocin.</a> Analytica Chimica Acta. 636 (1), 111-115 (2009).</li><li>Solangi, A. R., Memon, S. Q., Mallah, A., Khuhawar, M. Y., Bhanger, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+separation+of+oxytocin,+norfloxacin+and+diclofenac+sodium+in+milk+samples+using+capillary+electrophoresis.">Quantitative separation of oxytocin, norfloxacin and diclofenac sodium in milk samples using capillary electrophoresis.</a> Biomedical Chromatography. 23 (9), 1007-1013 (2009).</li><li>Klein, B. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+modulates+markers+of+the+unfolded+protein+response+in+Caco2BB+gut+cells.">Oxytocin modulates markers of the unfolded protein response in Caco2BB gut cells.</a> Cell Stress and Chaperones. 19 (4), 465-477 (2014).</li><li>Klein, B. Y., Tamir, H., Hirschberg, D. L., Glickstein, S. B., Welch, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+modulates+mTORC1+pathway+in+the+gut.">Oxytocin modulates mTORC1 pathway in the gut.</a> Biochemical and Biophysical Research Communications. 432 (3), 466-471 (2013).</li><li>Klein, B. Y., Tamir, H., Ludwig, R. J., Glickstein, S. B., Welch, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colostrum+oxytocin+modulates+cellular+stress+response,+inflammation,+and+autophagy+markers+in+newborn+rat+gut+villi.">Colostrum oxytocin modulates cellular stress response, inflammation, and autophagy markers in newborn rat gut villi.</a> Biochemical an Biophysical Research Communications. 487 (1), 47-53 (2017).</li><li>Donnet-Hughes, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential+role+of+the+intestinal+microbiota+of+the+mother+in+neonatal+immune+education.">Potential role of the intestinal microbiota of the mother in neonatal immune education.</a> Proceedings of the Nutritional Society. 69 (3), 407-415 (2010).</li><li>Perez, P. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+imprinting+of+the+neonatal+immune+system:+lessons+from+maternal+cells?.">Bacterial imprinting of the neonatal immune system: lessons from maternal cells?.</a> Pediatrics. 119 (3), e724-e732 (2007).</li><li>Takeda, S., Kuwabara, Y., Mizuno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concentrations+and+origin+of+oxytocin+in+breast+milk.">Concentrations and origin of oxytocin in breast milk.</a> Endocrinolcia Japonica. 33 (6), 821-826 (1986).</li><li>Quintana, D. S., Outhred, T., Westlye, L. T., Malhi, G. S., Andreassen, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+oxytocin+administration+on+brain+activity:+a+systematic+review+and+meta-analysis+protocol.">The impact of oxytocin administration on brain activity: a systematic review and meta-analysis protocol.</a> Systematic Reviews. 5 (1), 205 (2016).</li><li>Dobbing, J., Sands, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+aspects+of+the+brain+growth+spurt.">Comparative aspects of the brain growth spurt.</a> Early Human Development. 3 (1), 79-83 (1979).</li><li>Orr, M. E., Garbarino, V. R., Salinas, A., Buffenstein, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extended+Postnatal+Brain+Development+in+the+Longest-Lived+Rodent:+Prolonged+Maintenance+of+Neotenous+Traits+in+the+Naked+Mole-Rat+Brain.">Extended Postnatal Brain Development in the Longest-Lived Rodent: Prolonged Maintenance of Neotenous Traits in the Naked Mole-Rat Brain.</a> Frontiers in Neuroscience. 10, 504 (2016).</li><li>Hansson, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-resolved+quantitative+proteome+analysis+of+in+vivo+intestinal+development.">Time-resolved quantitative proteome analysis of in vivo intestinal development.</a> Molecular and Cellular Proteomics. 10 (3), (2011).</li><li>Mochizuki, K., Yorita, S., Goda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression+changes+in+the+jejunum+of+rats+during+the+transient+suckling-weaning+period.">Gene expression changes in the jejunum of rats during the transient suckling-weaning period.</a> Journal of Nutritional Science and Vitaminology (Tokyo). 55 (2), 139-148 (2009).</li><li>Rinaman, L., Banihashemi, L., Koehnle, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+life+experience+shapes+the+functional+organization+of+stress-responsive+visceral+circuits.">Early life experience shapes the functional organization of stress-responsive visceral circuits.</a> Physiology and Behavior. 104 (4), 632-640 (2011).</li><li>Johannes, G., Sarnow, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cap-independent+polysomal+association+of+natural+mRNAs+encoding+c-myc,+BiP,+and+eIF4G+conferred+by+internal+ribosome+entry+sites.">Cap-independent polysomal association of natural mRNAs encoding c-myc, BiP, and eIF4G conferred by internal ribosome entry sites.</a> RNA. 4 (12), 1500-1513 (1998).</li><li>Rinaman, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hindbrain+noradrenergic+A2+neurons:+diverse+roles+in+autonomic,+endocrine,+cognitive,+and+behavioral+functions.">Hindbrain noradrenergic A2 neurons: diverse roles in autonomic, endocrine, cognitive, and behavioral functions.</a> American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 300 (2), R222-R235 (2011).</li><li>Walker, C. D., Toufexis, D. J., Burlet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypothalamic+and+limbic+expression+of+CRF+and+vasopressin+during+lactation:+implications+for+the+control+of+ACTH+secretion+and+stress+hyporesponsiveness.">Hypothalamic and limbic expression of CRF and vasopressin during lactation: implications for the control of ACTH secretion and stress hyporesponsiveness.</a> Progress in Brain Research. 133, 99-110 (2001).</li><li>Montiel-Castro, A. J., Gonzalez-Cervantes, R. M., Bravo-Ruiseco, G., Pacheco-Lopez, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+microbiota-gut-brain+axis:+neurobehavioral+correlates,+health+and+sociality.">The microbiota-gut-brain axis: neurobehavioral correlates, health and sociality.</a> Frontiers in Integrative Neuroscience. 7, 70 (2013).</li><li>Blevins, J. E., Ho, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+oxytocin+signaling+in+the+regulation+of+body+weight.">Role of oxytocin signaling in the regulation of body weight.</a> Reviews in Endocrine and Metabolic Disorders. 14 (4), 311-329 (2013).</li><li>Welch, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+administration+of+secretin+and+oxytocin+inhibits+chronic+colitis+and+associated+activation+of+forebrain+neurons.">Combined administration of secretin and oxytocin inhibits chronic colitis and associated activation of forebrain neurons.</a> Neurogastroenterology Motility. 22 (6), 654 (2010).</li><li>Berthoud, H. R., Neuhuber, W. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+and+chemical+anatomy+of+the+afferent+vagal+system.">Functional and chemical anatomy of the afferent vagal system.</a> Autonomic Neuroscience: Basic and Clinical. 85 (1-3), 1-17 (2000).</li><li>Taniuchi, S., Miyake, M., Tsugawa, K., Oyadomari, M., Oyadomari, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+stress+response+of+vertebrates+is+regulated+by+four+eIF2alpha+kinases.">Integrated stress response of vertebrates is regulated by four eIF2alpha kinases.</a> Scientific Reports. 6, 32886 (2016).</li><li>Altschuler, S. M., Bao, X. M., Bieger, D., Hopkins, D. A., Miselis, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viscerotopic+representation+of+the+upper+alimentary+tract+in+the+rat:+sensory+ganglia+and+nuclei+of+the+solitary+and+spinal+trigeminal+tracts.">Viscerotopic representation of the upper alimentary tract in the rat: sensory ganglia and nuclei of the solitary and spinal trigeminal tracts.</a> Journal of Comparative Neurology. 283 (2), 248-268 (1989).</li><li>Shapiro, R. E., Miselis, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+central+neural+connections+of+the+area+postrema+of+the+rat.">The central neural connections of the area postrema of the rat.</a> Journal of Comparative Neurology. 234 (3), 344-364 (1985).</li><li>Paxinos, G., Watson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Rat Brain in Stereotaxic Coordinates. , (1997).</li><li>Nayak, R., Pintel, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adeno-associated+viruses+can+induce+phosphorylation+of+eIF2alpha+via+PKR+activation,+which+can+be+overcome+by+helper+adenovirus+type+5+virus-associated+RNA.">Adeno-associated viruses can induce phosphorylation of eIF2alpha via PKR activation, which can be overcome by helper adenovirus type 5 virus-associated RNA.</a> Journal of Virology. 81 (21), 11908-11916 (2007).</li><li>Zaborske, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+analysis+of+tRNA+charging+and+activation+of+the+eIF2+kinase+Gcn2p.">Genome-wide analysis of tRNA charging and activation of the eIF2 kinase Gcn2p.</a> Journal of Biological Chemistry. 284 (37), 25254-25267 (2009).</li><li>Hollis, J. H., Lightman, S. L., Lowry, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+systemic+and+visceral+sensory+information+by+medullary+catecholaminergic+systems+during+peripheral+inflammation.">Integration of systemic and visceral sensory information by medullary catecholaminergic systems during peripheral inflammation.</a> Annals of the New York Academy of Sciences. 1018, 71-75 (2004).</li><li>Klein, B. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxytocin+opposes+effects+of+bacterial+endotoxin+on+ER-stress+signaling+in+Caco2BB+gut+cells.">Oxytocin opposes effects of bacterial endotoxin on ER-stress signaling in Caco2BB gut cells.</a> Biochimica et Biophysica Acta. 1860 (2), 402-411 (2016).</li><li>Kaltschmidt, B., Kaltschmidt, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NF-kappaB+in+the+nervous+system.">NF-kappaB in the nervous system.</a> Cold Spring Harbor Perspectives in Biology. 1 (3), a001271 (2009).</li></ol>

A technique for microdissection of discrete, OTR-rich brain nuclei in the neonatal rat brain is presented in this paper. It is well recognized that neurons are highly specialized, even within well-characterized nuclei in the brain. This highly reproducible approach to isolate specific OTR-rich nuclei enables robust hypothesis testing. Using automated Western blotting, the consistency and reproducibility of the results were further improved. While a limitation of this technique remains modest brain punch variability; this...

In contrast to our understanding of early brain development occurring over the course of days-to-weeks postpartum, relatively little is known about the myriad of dynamic changes occurring in the first hours of life in rats. A key challenge has been the small size of the neonatal rat brain and a requirement for high-tech tools to isolate discrete brain regions or single cells. Studies often assess gene transcription and not translation1,2, which does not give a firm understanding of functional levels of activated signaling molecules. Others examine expression using immunohistochemistry to reference brain regions, which does not allow for the quantification of expression levels3. No study to date has examined the activation of signaling pathways associated with rats&#39; first colostrum feed in discrete brain regions, which requires rapid isolation and sacrifice and measurement of protein expression and protein phosphorylation using Western blotting. While brain microdissection is performed on older and larger brains, we have not identified a reference performing a non-single-cell brain punch in a P0 brain. This paper presents a protocol for isolating restricted regions of the neonatal brain using a relatively low-tech punch technique and a Western blotting procedure to measure protein expression in relatively small samples. This protocol may be suitable for research questions that require the assessment of protein expression and post-translational modifications (e.g., phosphorylation) in relatively restricted regions of small brains of any species, provided that the user can visually identify the brain region of interest with an atlas and identifiable landmarks.
This technique was developed to understand changes occurring in the brain as a result of the neonatal rats&#39; first colostrum feed, which is rich in oxytocin (OT). OT has been long known for its ability to stimulate milk let-down and uterine contraction. However, OT is now known to play a wide range of roles in the regulation of many bodily functions and behaviors4. For example, OT opposes stress and inflammation in conjunction with adaptive affiliative behaviors5, delays gastric emptying, and slows intestinal transit. OT receptors (OTR) have been identified in enteric neurons and intestinal epithelium6,7,8. The gastrointestinal effects of OT are particularly important to the infant during the early postnatal period. For instance, breastfeeding is associated with the delivery of significant quantities of OT to the neonatal gut9,10, and data show that the OTR is heavily overexpressed in duodenal villi during the milk suckling period8.
In vitro experiments using a gut cell line have demonstrated at the cellular level that oxytocin modulates important molecules in the stress signaling pathway11,12 and plays a regulatory role in translation of proteins12. These studies suggest that components of milk, including exogenous oxytocin from the mother, are important in the unfolded protein response in neonates to reduce cellular stress13.
In vivo and ex vivo studies have shown that colostrum OT modulates the cellular stress response, inflammation, and autophagy markers in newborn rat gut villi. Newborn enterocytes suffer substantial cellular stress on their luminal side when the gut is simultaneously exposed to microbiota from the mother in colostrum14,15 and numerous proteins, including hormones such as OT9,10,16.
The effects of OT on the brain have been studied17. However, the OT signaling mechanisms demonstrated in the gut during the early postnatal period have not been studied in the brain. In this paper, a method for isolating discrete brain nuclei in the neonatal rat brainstem and hypothalamus using electrophoresis is used to profile isolated brain regions. The overall goal of this method is to capture the state of cell signaling in brain areas as close as possible to birth, before and after the first milk suckling, in brain tissue with the lowest glial/neuronal index. The rationale for the development of this technique is that it allows for the rapid isolation of restricted, microscopic brain regions in neonatal pups with a more homogenous collection of neurons for ex vivo studies using an automated Western blotting methodology, offering highly consistent results on relatively small dissected samples. A shortcoming of prior work includes more gross dissection (brain slices or whole brain) and older animals18,19. The brains of young pups are incredibly dynamic, featuring waves of glial differentiation after birth. In order to study brain changes influenced by the pups&#39; first feeding, studying restricted neuronal nuclei with reproducible dissection is necessary.
Milk feed is usually analyzed for its immunological and nutritional impact on health or gene expression (for example, in enterocytes20,21), whereas its effect on brain areas during brain development is rarely studied. The effect of milk transit in the gut on brain function was analyzed in reference to gut cholecystokinin receptors vagal relay to brain stem nuclei, but not to intracellular signaling pathways22. There is a vast literature on vulnerability of the developing neonate brain to malnutrition of mothers during pregnancy23, but the stress and inflammation signals are not addressed. Importantly, the current method takes advantage of a phenomenon in day-zero rat newborns that isolates the blood-born colostrum stimuli from vagal relay of visceral stimuli. This is the so-called stress hypo-responsiveness period characterized by immature nucleus tractus solitarius (NTS)-hypothalamic circuit immediately after birth24,25 that restricts NTS, paraventricular nucleus (PVN), and supraoptic nucleus (SON) signals to blood-born stimuli.
This method is useful for analysis of multiple signaling pathways and relatively restricted to neuronal cells, provided that brain tissue is harvested at postnatal day-0 in rats, in addition to whether mothers have been challenged or not by any kind of treatment during pregnancy. Litters can be analyzed for the effects of colostrum feed versus pre-feeding signaling. When comparing signals between brain areas with poor versus rich protein yield, this method enables in-capillary determination of total protein of the polypeptide bands in capillaries run parallel to immune-quantitation of protein antigens. This method enables the quantitative comparison, using arbitrary units, of results obtained by the same antibody without standard quantitative curves and by reference to total protein per capillary. Comparing results obtained by different antibodies is possible only using quantitative standard curves.
This method allowed for the assessment of bidirectional signaling occurring between the gut and the brain and that can impact function in both organs26. The association between oxytocin and food intake, which has been extensively studied in recent years27, supports a link between increased oxytocin signaling and nutrient availability. These studies also support the converse concept that energy deficits are coupled with reductions in hypothalamic oxytocin signaling.
Earlier studies of the effect of OT on brain activity demonstrated that induced gut inflammation elicited cFos transcription in hypothalamic PVN, amygdala, and piriform cortex which was refractory to vagotomy28. However, systemic infusion of OT with secretin decreased the brain cFos response to the provoked inflammatory reaction in the gut28. This suggested that the effect of exogenous OT was carried out by routes other than vagal relays, possibly via blood-borne signaling molecules carried through the area postrema6,29.
In this study, the cellular stress signaling pathways that have previously observed in the gut were assessed in the brain. The hypothesis was that milk components may protect or defer the effect of inflammation on gut permeability to microbial and other metabolites, and in turn, the effects on brain function. The clear antagonistic differences in IkB versus BiP signaling found in villi, before and after priming by colostrum13, suggested that the brains of neonates, still in the process of developing, may sense these colostrum-induced gut signals.
Signaling protein markers used in previous gut experiments that are associated with endoplasmic reticulum stress were measured. They include the ER chaperone BiP, translation initiation factor eIF2a (which serves as a stress response integrator30), eIF2a kinase p-PKR, and two inflammation-signaling proteins (NF-kB and its inhibitor, IkB).
Six brain regions based on their ability in adults to secrete or respond to OT were chosen. The NTS, located at the upper medulla, is the first relay of the visceral input and receives direct signaling from vagal sensory neurons in the gut31 and possibly blood-born cytokines, toxins, and hormones via the adjacent area-postrema32. The PVN, supraoptic nucleus (SON), striatum nuclei (STR), cerebral cortex (CX), and medial preoptic nucleus (MPO) receive signaling from the gut via the NTS.
Results showed that the cellular stress response during the immediate postnatal period prior to colostrum priming and immediately after first feeding is different in NTS compared to PVN and SON. Signaling in CX, STR, and MPO differed from that of PVN and SON, as well. The distinct protective functions of OT shown previously to modulate cell stress and inflammation in the gut are likely sensed by some areas of the brain. Collectively, the data indicate that at the cellular level, during the first hours after birth, the brain responds to the metabolic stress associated with nutrient insufficiency. The data also show that the extent and direction of the modulating effects of the colostrum feed are region-dependent and that in some regions, they mirror OT effects shown previously in the gut.

<table>
	<tbody>
		<tr>
			<td>Bradford solution</td>
			<td>Bio Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Protein lysis kit</td>
			<td>Protein simple</td>
			<td>CBS403</td>
			<td>Bicine/CHAPS</td>
		</tr>
		<tr>
			<td>WES kits</td>
			<td>Protein simple</td>
			<td>WES-Mouse 12-230 master kit (PS-MK15), WES-Rabbit 12-230 master kit (PS-MK14), WES 12-230 kDa total Protein master kit (PS-TP07)</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-mouse IgG HRP conjugate</td>
			<td>Protein simple</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-phospho-eIF2a</td>
			<td>Cell Signaling technology</td>
			<td>SER51, 9721</td>
			<td></td>
		</tr>
		<tr>
			<td>mouse mAb anti-PKR</td>
			<td>Cell Signaling technology</td>
			<td>2103</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-phospho-PKR</td>
			<td>Millipore</td>
			<td>Thr451, 07-886</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit mAb anti-PKR</td>
			<td>Cell Signaling technology</td>
			<td>12297</td>
			<td></td>
		</tr>
		<tr>
			<td>rabbit mAb anti-GAPDH</td>
			<td>Cell Signaling technology</td>
			<td>2118</td>
			<td></td>
		</tr>
		<tr>
			<td>mouse mAb anti-phospho-IKB</td>
			<td>Cell Signaling technology</td>
			<td>9246</td>
			<td></td>
		</tr>
		<tr>
			<td>mouse mAb anti-IKB</td>
			<td>Cell Signaling technology</td>
			<td>4814</td>
			<td></td>
		</tr>
		<tr>
			<td>rabbit anti-BiP</td>
			<td>Cell Signaling technology</td>
			<td>3183</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti GCN2</td>
			<td>Cell Signaling technology</td>
			<td>3302</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit mAb anti-phospho-GCN2</td>
			<td>BIORBYT</td>
			<td>T899</td>
			<td></td>
		</tr>
		<tr>
			<td>pregnant Sprague-Dawley rats</td>
			<td>Charles River Laboratories</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Punch device</td>
			<td>WellTech Rapid Core or Harris Uni-Core</td>
			<td>0.35, 0.50, 0.75, 1.0, 1.20, 1.50</td>
			<td></td>
		</tr>
	</tbody>
</table>

assessing cellular stress and inflammation in discrete oxytocin-secreting brain nuclei in the neonatal rat before and after first colostrum feeding

The goal of this protocol is to isolate oxytocin-receptor rich brain nuclei in the neonatal brain before and after first colostrum feeding. The expression of proteins known to respond to metabolic stress was measured in brain-nuclei isolates using Western blotting. This was done to assess whether metabolic stress-induced nutrient insufficiency in the body triggered neuronal stress. We have previously demonstrated that nutrient insufficiency in neonates elicits metabolic stress in the gut. Furthermore, colostrum oxytocin modulates cellular stress response, inflammation, and autophagy markers in newborn rat gut villi prior to and after first feed. Signaling protein markers associated with the endoplasmic reticulum stress [ER chaperone binding immunoglobulin protein (BiP), eukaryotic translation initiation factor 2A (eIF2a), and eIF2a kinase protein kinase R (p-PKR)], as well as two inflammation-signaling proteins [nuclear factor-&#954;B (NF-kB) and inhibitor &#954;B (IkB)], were measured in newborn brain nuclei [nucleus of the solitary tract (NTS), paraventricular nucleus (PVN), supra-optic nucleus (SON), cortex (CX), striatum nuclei (STR), and medial preoptic nucleus (MPO)] before the first feed (unprimed by colostrum) and after the start of nursing (primed by colostrum). Expression of BiP/GRP78 and p-eIF2a were upregulated in unprimed and downregulated in primed NTS tissue. NF-kB was retained (high) in the CX, STR, and MPO cytoplasm, whereas NF-kB was lower and unchanged in NTS, PVN, and SON in both conditions. The collective BiP and p-eIF2 findings are consistent with a stress response. eIf2a was phosphorylated by dsRNA dependent kinase (p-PKR) in the SON, CX, STR, and MPO. However, in the NTS (and to a lesser extent in PVN), eIf2a was phosphorylated by another kinase, general control nonderepressible-2 kinase (GCN2). The stress-modulating mechanisms previously observed in newborn gut enterocytes appear to be mirrored in some OTR-rich brain regions. The NTS and PVN may utilize a different phosphorylation mechanism (under nutrient deficiency) from other regions and be refractory to the impact of nutrient insufficiency. Collectively, this data suggests that brain responses to nutrient insufficiency stress are offset by signaling from colostrum-primed enterocytes.

The representative bands of immunoreactivity relative to total protein show that there are brain nuclei with very low harvested protein. This requires the use of the automated Western blot technique, which is highly sensitive compared to the canonical Western blot. This approach can be run with fortyfold less protein per capillary compared to the per-lane in Western blots.
Differential effects of colostrum priming on BiP levels in ...

Watch this Scientific Journal Video about Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding at JoVE.co

Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding

Here, we present a protocol to isolate brain nuclei in the neonatal rat brain in conjunction with first colostrum feeding. This technique allows the study of nutrient insufficiency stress in the brain as modulated by enterocyte signaling.

The goal of this protocol is to isolate oxytocin-receptor rich brain nuclei in the neonatal brain before and after first colostrum feeding. The expression ...

This method can help answer key questions in the post-natal development field about the way milk suckling influences stress signaling in the brain. This technique can be used to capture specific brain areas during the first natural starvation period and to compare them to respective areas shortly after the first natural colostrum feed. Understanding how suckling influences the physiology of behavior and emotion enables the use of an antagonist to various receptors during ex-vivo brain tissue analysis.To obtain the nuclei punches, remove the rat pups by their tail with a gloved hand. After harvesting the brain, rapidly place the whole organ in a polymethyl methacrylate brain mold at room temperature and immediately use a new razor blade to make 500 micrometer thick slices of the tissue. Lay the slices rostral to caudal in a Petri dish as they are obtained to maintain the correct orientation of the sections.When the entire brain has been sectioned, quickly add artificial cerebral spinal fluid without glucose to the dish and incubate the slices for 60 minutes at 28 to 30 degrees Celsius with constant stirring on an orbital shaker. Use a brain atlas and anatomic landmarks on each tissue to identify the brain nuclei to be punched and place the slice with the nuclei of interest in a new Petri dish under a dissecting microscope. Once visualized, use a coring tool to quickly punch out four to six different nuclei and rapidly immerse each punched nucleus in 0.06 mL of ice cold protein extraction buffer in the appropriately labeled micro-centrifuge tube containing proteus inhibitors and phosphatase inhibitors for 60 minutes.At the end of the incubation, centrifuge the extracted nuclei in a cooled mini-centrifuge, and use a micro-pipette to carefully transfer 0.055 mL of supernatant from each tube into the appropriate pre-cooled 1.5 mL micro-centrifuge tube on ice. Before negative 20 degrees Celsius storage, transfer 0.012 mL of supernatant from each protein stock tube into the appropriate 0.5 mL pre-cooled tube on ice for the first sample preparation. To prepare the samples for in-capillary protein measurement, add 0.003 mL of master mix reagent from a protein lysis kit to each of the samples in the 0.5 mL labeled tubes.Next, add 0.004 mL of master mix reagent to a biotinylated molecular weight ladder solution in 0.016 mL of deionized water, and denature the ladder and protein extract samples in a 95 degrees Celsius heat block, storing all of the tubes at four degrees Celsius after five minutes. For signal protein analysis, add 0.01 mL of freshly prepared luminol peroxide solution to wells E-1 to E-25 of a new automated Western plate, 0.01 mL of secondary anti-mouse antibody to wells D-2 to D-25, and add 0.01 mL of streptavidin horseradish peroxidase from the kit to well D-1. Add 0.01 mL of freshly prepared primary antibody into wells C-2 to C-25, and 0.01 mL of antibody diluent two solution to wells C-1 and B-1 to B-25.Leave the row F wells empty and fill the five compartments of the three rows below the F row with 0.45 mL of wash buffer. Next, briefly spin the refrigerated samples for 30 seconds and add 0.03 mL of each sample to each well of row A, starting with A-2. Then, add 0.005 mL of the biotinylated molecular weight ladder to well A-1 and cover the plate for centrifugation.While the plate is centrifuged, open a new run file in the automated Western associated software and initiate a molecular size assay. In the assay page, enter the sample names into each capillary as well as the names of the primary and secondary antibodies. At the end of the centrifugation, place the plate in the automated Western instrument and peel the cover from the capillary cartridge box.Following centrifugation, don't forget to inspect for air bubbles, because air bubbles in the capillary can block the electrophoretic current and fail the entire round. Insert the cartridge into the designated position within the instrument and close the door. Click start.When prompted with the type of the assay, enter the name of the experiment into the appropriate text box and click okay. When prompted by the activated run date and the ID number on the run file, make a note of the time when the run ends. At the end of the run, discard the capillary cartridge into the sharps disposal and the plate into the biohazardous materials disposal.After the electrophoresis separation, check the run files for immune reactivity peaks of antigens at 40 to 43 kilodaltons which stand for phosphorylated eukaryotic translation initiation factor 2A. Where molecular weight peaks of this size are missing, right click below the curve and select add molecular weight to peak to ensure that the sizes and arbitrary quantities below the curve are recorded. Within the unprimeds tissue samples, binding amino globulin protein levels in the nuclei of the solitary track are significantly higher compared to all of the other regions.Priming of the gut tissue with colostrum decreases binding amino globulin protein levels in the nuclei of the solitary track and has no effect on paraventricular nuclei and super-optic nuclei. Conversely, priming increases binding amino globulin protein levels within the cortex, striation nuclei, and medial preoptic nuclei relative to the unprimed tissue, implying that binding amino globulin protein levels in the various tested brain nuclei respond differently to gut priming and there is not yet any demonstrated crosstalk between the various nuclei tested. Eukaryotic translation initiation factor 2A and phosphorylated eukaryotic translation initiation factor 2A levels are elevated in the unprimed condition relative to other nuclei.After priming, levels of both eukaryotic translation initiation factor 2A and phosphorylated eukaryotic translation initiation factor 2A are reduced relative to nuclei of the solitary track compared to unprimed tissue. In all other tested nuclei, priming increases the levels of eukaryotic translation initiation factor 2A and phosphorylated eukaryotic translation initiation factor 2A relative to unprimed tissue. However, levels of phosphorylated protein kinase receptor are low in unprimed samples relative to primed samples in nuclei of the solitary track, strongly suggesting that another kinase is involved in the phosphorylation of eukaryotic translation initiation factor 2A.After its development, this technique paved the way for researchers in the field of post-natal development to explore the signaling pathways involved in tissue growth and differentiation and whether they are influenced by or independent of suckling. Don't forget that working with volatile reducing agents like, for example, dithiothreitol, can be hazardous, and precautions such as preparation in the chemical hood should always be taken when preparing this procedure.

assessing-cellular-stress-inflammation-discrete-oxytocin-secreting

Research

JoVE Journal

Immunology and Infection

Seven Steps to Stellate Cells

Hepatic stellate cells are liver-resident cells of star-like morphology and are located in the space of Disse between liver sinusoidal endothelial cells and hepatocytes1,2. Stellate cells are derived from bone marrow precursors and store up to 80% of the total body vitamin A1, 2. Upon activation, stellate cells differentiate into myofibroblasts to produce extracellular matrix, thus contributing to liver fibrosis3. Based on their ability to contract, myofibroblastic stellate cells can regulate the vascular tone associated with portal hypertension4. Recently, we demonstrated that hepatic stellate cells are potent antigen presenting cells and can activate NKT cells as well as conventional T lymphocytes5. 

 Here we present a method for the efficient preparation of hepatic stellate cells from mouse liver. Due to their perisinusoidal localization, the isolation of hepatic stellate cells is a multi-step process. In order to render stellate cells accessible to isolation from the space of Disse, mouse livers are perfused in situ with the digestive enzymes Pronase E and Collagenase P. Following perfusion, the liver tissue is subjected to additional enzymatic treatment with Pronase E and Collagenase P in vitro. Subsequently, the method takes advantage of the massive amount of vitamin A-storing lipid droplets in hepatic stellate cells. This feature allows the separation of stellate cells from other hepatic cell types by centrifugation on an 8% Nycodenz gradient. The protocol described here yields a highly pure and homogenous population of stellate cells. Purity of preparations can be assessed by staining for the marker molecule glial fibrillary acidic protein (GFAP), prior to analysis by fluorescence microscopy or flow cytometry. Further, light microscopy reveals the unique appearance of star-shaped hepatic stellate cells that harbor high amounts of lipid droplets. 


 Taken together, we present a detailed protocol for the efficient isolation of hepatic stellate cells, including representative images of their morphological appearance and GFAP expression that help to define the stellate cell entity.

Here we describe a method for the isolation of hepatic stellate cells from mouse liver. For stellate cell purification, mouse livers are digested in situ and in vitro by pronase-collagenase treatment prior to density gradient centrifugation. This technique yields highly pure hepatic stellate cells.

Hepatic stellate cells are liver-resident  cells of star-like morphology and are located in the space of Disse between  liver sinusoidal endothelial cells ...

Trichuris muris Infection: A Model of Type 2 Immunity and Inflammation in the Gut

Trichuris muris is a natural pathogen of mice and is biologically and antigenically similar to species of Trichuris that 
infect humans and livestock1. Infective eggs are given by oral gavage, hatch in the distal small intestine, invade the intestinal epithelial cells (IECs) 
that line the crypts of the cecum and proximal colon and upon maturation the worms release eggs into the environment1. This model is a powerful tool to 
examine factors that control CD4+ T helper (Th) cell activation as well as changes in the intestinal epithelium. The immune response that occurs in 
resistant inbred strains, such as C57BL/6 and BALB/c, is characterized by Th2 polarized cytokines (IL-4, IL-5 and IL-13) and expulsion of worms while Th1-associated 
cytokines (IL-12, IL-18, IFN-&gamma;) promote chronic infections in genetically susceptible AKR/J mice2-6. Th2 cytokines promote physiological changes in 
the intestinal microenvironment including rapid turnover of IECs, goblet cell differentiation, recruitment and changes in epithelial permeability and smooth muscle 
contraction, all of which have been implicated in worm expulsion7-15. Here we detail a protocol for propagating Trichuris muris eggs which can 
be used in subsequent experiments. We also provide a sample experimental harvest with suggestions for post-infection analysis. Overall, this protocol will provide 
researchers with the basic tools to perform a Trichuris muris mouse infection model which can be used to address questions pertaining to Th proclivity in 
the gastrointestinal tract as well as immune effector functions of IECs.

Trichuris muris Infection: A Model of Type 2 Immunity and Inflammation in the Gut

Trichuris muris infection is an intestinal model of Th2 immunity where resistant mice generate a protective Th2 response and susceptible mice generate a pathological Th1 response.

Trichuris muris is a natural pathogen of mice and is biologically and antigenically similar to species of Trichuris that 
infect humans and livestock1. ...

Assessing Somatic Hypermutation in Ramos B Cells after Overexpression or Knockdown of Specific Genes

B cells start their life with low affinity antibodies generated by V(D)J recombination. However, upon detecting a pathogen, the variable (V) region of an immunoglobulin (Ig) gene is mutated approximately 100,000-fold more than the rest of the genome through somatic hypermutation (SHM), resulting in high affinity antibodies1,2. In addition, class switch recombination (CSR) produces antibodies with different effector functions depending on the kind of immune response that is needed for a particular pathogen. Both CSR and SHM are initiated by activation-induced cytidine deaminase (AID), which deaminates cytosine residues in DNA to produce uracils. These uracils are processed by error-prone forms of repair pathways, eventually leading to mutations and recombination1-3.
Our current understanding of the molecular details of SHM and CSR come from a combination of studies in mice, primary cells, cell lines, and cell-free experiments. Mouse models remain the gold standard with genetic knockouts showing critical roles for many repair factors (e.g. Ung, Msh2, Msh6, Exo1, and polymerase &eta;)4-10. However, not all genes are amenable for knockout studies. For example, knockouts of several double-strand break repair proteins are embryonically lethal or impair B-cell development11-14. Moreover, sometimes the specific function of a protein in SHM or CSR may be masked by more global defects caused by the knockout. In addition, since experiments in mice can be lengthy, altering expression of individual genes in cell lines has become an increasingly popular first step to identifying and characterizing candidate genes15-18.
Ramos &#x2013; a Burkitt lymphoma cell line that constitutively undergoes SHM &#x2013; has been a popular cell-line model to study SHM18-24. One advantage of Ramos cells is that they have a built-in convenient semi-quantitative measure of SHM. Wild type cells express IgM and, as they pick up mutations, some of the mutations knock out IgM expression. Therefore, assaying IgM loss by fluorescence-activated cell scanning (FACS) provides a quick read-out for the level of SHM. A more quantitative measurement of SHM can be obtained by directly sequencing the antibody genes. 
Since Ramos cells are difficult to transfect, we produce stable derivatives that have increased or lowered expression of an individual gene by infecting cells with retroviral or lentiviral constructs that contain either an overexpression cassette or a short hairpin RNA (shRNA), respectively. Here, we describe how we infect Ramos cells and then use these cells to investigate the role of specific genes on SHM (Figure 1).

We describe how to perform retroviral or lentiviral infections of overexpression or shRNA-containing constructs in the human Ramos B-cell line and how to measure somatic hypermutation in these cells.

B cells start their life with low affinity antibodies generated by V(D)J recombination.  However, upon detecting a pathogen, the variable (V) region of an ...

Primary Microglia Isolation from Mixed Glial Cell Cultures of Neonatal Rat Brain Tissue

Microglia account for approximately 12% of the total cellular population in the mammalian brain. While neurons and astrocytes are considered the major cell types of the nervous system, microglia play a significant role in normal brain physiology by monitoring tissue for debris and pathogens and maintaining homeostasis in the parenchyma via phagocytic activity 1,2. Microglia are activated during a number of injury and disease conditions, including neurodegenerative disease, traumatic brain injury, and nervous system infection 3. Under these activating conditions, microglia increase their phagocytic activity, undergo morpohological and proliferative change, and actively secrete reactive oxygen and nitrogen species, pro-inflammatory chemokines and cytokines, often activating a paracrine or autocrine loop 4-6. As these microglial responses contribute to disease pathogenesis in neurological conditions, research focused on microglia is warranted.
	Due to the cellular heterogeneity of the brain, it is technically difficult to obtain sufficient microglial sample material with high purity during in vivo experiments. Current research on the neuroprotective and neurotoxic functions of microglia require a routine technical method to consistently generate pure and healthy microglia with sufficient yield for study. We present, in text and video, a protocol to isolate pure primary microglia from mixed glia cultures for a variety of downstream applications. Briefly, this technique utilizes dissociated brain tissue from neonatal rat pups to produce mixed glial cell cultures. After the mixed glial cultures reach confluency, primary microglia are mechanically isolated from the culture by a brief duration of shaking. The microglia are then plated at high purity for experimental study.
	The principle and protocol of this methodology have been described in the literature 7,8. Additionally, alternate methodologies to isolate primary microglia are well described 9-12. Homogenized brain tissue may be separated by density gradient centrifugation to yield primary microglia 12. However, the centrifugation is of moderate length (45 min) and may cause cellular damage and activation, as well as, cause enriched microglia and other cellular populations. Another protocol has been utilized to isolate primary microglia in a variety of organisms by prolonged (16 hr) shaking while in culture 9-11. After shaking, the media supernatant is centrifuged to isolate microglia. This longer two-step isolation method may also perturb microglial function and activation. We chiefly utilize the following microglia isolation protocol in our laboratory for a number of reasons: (1) primary microglia simulate in vivo biology more faithfully than immortalized rodent microglia cell lines, (2) nominal mechanical disruption minimizes potential cellular dysfunction or activation, and (3) sufficient yield can be obtained without passage of the mixed glial cell cultures.
	It is important to note that this protocol uses brain tissue from neonatal rat pups to isolate microglia and that using older rats to isolate microglia can significantly impact the yield, activation status, and functional properties of isolated microglia. There is evidence that aging is linked with microglia dysfunction, increased neuroinflammation and neurodegenerative pathologies, so previous studies have used ex vivo adult microglia to better understand the role of microglia in neurodegenerative diseases where aging is important parameter. However, ex vivo microglia cannot be kept in culture for prolonged periods of time. Therefore, while this protocol extends the life of primary microglia in culture, it should be noted that the microglia behave differently from adult microglia and in vitro studies should be carefully considered when translated to an in vivo setting.

Isolating primary microglia from the cellular heterogeneity of the brain is essential to investigate their role in both physiological and pathological conditions. This protocol describes a mechanical isolation and mixed cell culture technique that provides high yield and high purity, viable primary microglial cells for in vitro study and downstream applications.

Microglia account for approximately 12% of the  total cellular population in the mammalian brain. While neurons and astrocytes are considered  the major ...

Culturing Microglia from the Neonatal and Adult Central Nervous System

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied.

We outline methods for the efficient and quick isolation/culture of viable microglia from the neonatal cerebral cortex and adult spinal cord. The dissection and plating of cortical microglia can be accomplished within 90 minutes, with the subsequent microglial harvest taking place ~ 10 days following the initial dissection.

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and ...

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal features of the natural infection. This protocol describes procedures for the establishment and evaluation of systemic infection due to neuropathogenic Escherichia coli K1 in the neonatal rat. Colonization of the gastrointestinal tract leads to dissemination of the pathogen along the gut-lymph-blood-brain course of infection and the model displays strong age dependency. A strain of E. coli O18:K1 with enhanced virulence for the neonatal rat produces exceptionally high rates of colonization, translocation to the blood compartment and invasion of the meninges following transit through the choroid plexus. As in the human host, penetration of the central nervous system is accompanied by local inflammation and an invariably lethal outcome. The model is of proven utility for studies of the mechanism of pathogenesis, for evaluation of therapeutic interventions and for assessment of bacterial virulence.

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Here, a procedure is described for the establishment of systemic infection in the neonatal rat with cultures of Escherichia coli K1. This non-invasive procedure permits colonization of the gastrointestinal tract, translocation of the pathogen to the systemic circulation, and invasion of the central nervous system at the choroid plexus.

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. ...

Assessing the Cellular Immune Response of the Fruit Fly, Drosophila melanogaster, Using an In Vivo Phagocytosis Assay

In all animals, innate immunity provides an immediate and robust defense against a broad spectrum of pathogens. Humoral and cellular immune responses are the main branches of innate immunity, and many of the factors regulating these responses are evolutionarily conserved between invertebrates and mammals. Phagocytosis, the central component of cellular innate immunity, is carried out by specialized blood cells of the immune system. The fruit fly, Drosophila melanogaster, has emerged as a powerful genetic model to investigate the molecular mechanisms and physiological impacts of phagocytosis in whole animals. Here we demonstrate an injection-based in vivo phagocytosis assay to quantify the particle uptake and destruction by Drosophila blood cells, hemocytes. The procedure allows researchers to precisely control the particle concentration and dose, making it possible to obtain highly reproducible results in a short amount of time. The experiment is quantitative, easy to perform, and can be applied to screen for host factors that influence pathogen recognition, uptake, and clearance.

Assessing the Cellular Immune Response of the Fruit Fly, Drosophila melanogaster, Using an In Vivo Phagocytosis Assay

This protocol describes an in vivo phagocytosis assay in adult Drosophila melanogaster to quantify phagocyte recognition and clearance of microbial infections.

In all animals, innate immunity provides an immediate and robust defense against a broad spectrum of pathogens. Humoral and cellular immune responses are ...

Highly Efficient Transfection of Primary Macrophages with In Vitro Transcribed mRNA

Macrophages are phagocytic cells specialized in detecting molecules of non-self origin. To this end, they are equipped with a large array of pattern recognition receptors (PRRs). Unfortunately, this also makes macrophages particularly challenging to transfect as the transfection reagent and the transfected nucleic acids are often recognized by the PRRs as non-self. Therefore, transfection often results in macrophage activation and degradation of the transfected nucleic acids or even in suicide of the macrophages. Here, we describe a protocol that allows highly efficient transfection of murine primary macrophages such as peritoneal macrophages (PM) and bone marrow-derived macrophages (BMDM) with mRNA in vitro transcribed from DNA templates such as plasmids. With this simple protocol, transfection rates of about 50-65% for PM and about 85% for BMDM are achieved without cytotoxicity or immunogenicity observed. We describe in detail the generation of mRNA for transfection from DNA constructs such as plasmids and the transfection procedure.

Macrophages, especially primary macrophages, are challenging to transfect as they specialize in detecting molecules of non-self origin. We describe a protocol that allows highly efficient transfection of primary macrophages with mRNA generated from DNA templates such as plasmids.

Macrophages are phagocytic cells specialized in detecting molecules of non-self origin. To this end, they are equipped with a large array of pattern ...

Blocking Lymph Flow by Suturing Afferent Lymphatic Vessels in Mice

Lymphatic vessels are critical in maintaining tissue fluid balance and optimizing immune protection by transporting antigens, cytokines, and cells to draining lymph nodes (LNs). Interruption of lymph flow is an important method when studying the function of lymphatic vessels. The afferent lymphatic vessels from the murine footpad to the popliteal lymph nodes (pLNs) are well-defined as the only routes for lymph drainage into the pLNs. Suturing these afferent lymphatic vessels can selectively prevent lymph flow to the pLNs. This method allows for interference in lymph flow with minimal damage to the lymphatic endothelial cells in the draining pLN, the afferent lymphatic vessels, as well as other lymphatic vessels around the area. This method has been used to study how lymph impacts high endothelial venules (HEV) and chemokine expression in the LN, and how lymph flows through the adipose tissue surrounding the LN in the absence of functional lymphatic vessels. With the growing recognition of the importance of lymphatic function, this method will have broader applications to further unravel the function of lymphatic vessels in regulating the LN microenvironment and immune responses.

A protocol to block lymph flow by surgical suturing of afferent lymphatic vessels is presented.

Lymphatic vessels are critical in maintaining tissue fluid balance and optimizing immune protection by transporting antigens, cytokines, and cells to ...