Name: free-floating immunostaining of mouse brains
Uploaded: 2021-10-07T13:30:00
Description: Watch this Scientific Journal Video about Free-floating Immunostaining of Mouse Brains at JoVE.com

The investigators were supported by grants from the NIH (K01DK119471 to CW; P01DK113954, R01DK115761, R01DK117281, R01DK125480, and R01DK120858 to YX), USDA/CRIS (51000-064-01S to YX), and American Heart Association Postdoctoral Fellowship (#829565) to LT.

C57BL/6J mice of both sexes (8-16 weeks of age) were used in the present study. Care of all animals and all procedures were approved by Baylor College of Medicine&#39;s Institutional Animal Care and Use Committees.
1. Perfusion
NOTE: Steps 1.1 - 1.6 are performed in a fume hood.
<ol>
	<li>Anesthesia
	<ol>
		<li>Pour 5 mL of isoflurane (see the Table of Materials) onto a paper towel placed at the bottom of a desiccator. Introduce t...

<ol>
	<li>Must, 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=The+Disease+burden+associated+with+overweight+and+obesity.">The Disease burden associated with overweight and obesity.</a> Journal of the American Medical Association. 282 (16), 1523-1529 (1999).</li><li>Apovian, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obesity:+definition,+comorbidities,+causes,+and+burden.">Obesity: definition, comorbidities, causes, and burden.</a> The American Journal of Managed Care. 22 (7), 176-185 (2016).</li><li>Wong, S. K., Chin, K. Y., Suhaimi, F. H., Fairus, A., Ima-Nirwana, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+metabolic+syndrome:+a+review.">Animal models of metabolic syndrome: a review.</a> Nutrition &amp; Metabolism. 13 (1), 1-12 (2016).</li><li>Kennedy, A. J., Ellacott, K. L., King, V. L., Hasty, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+the+metabolic+syndrome.">Mouse models of the metabolic syndrome.</a> Disease Models &amp; Mechanisms. 3 (3-4), 156-166 (2010).</li><li>Schacht, V., Kern, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basics+of+immunohistochemistry.">Basics of immunohistochemistry.</a> The Journal of Investigative Dermatology. 135 (3), 1-4 (2015).</li><li>Mepham, B. L., Britten, K. J. M., Jones, D. B., Wright, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunostaining+methods+for+frozen+and+paraffin+sections.">Immunostaining methods for frozen and paraffin sections.</a> Lymphoproliferative Diseases. 15, 187-211 (1990).</li><li>Liu, H., 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=TPH2+in+the+dorsal+raphe+nuclei+regulates+energy+balance+in+a+sex-dependent+manner.">TPH2 in the dorsal raphe nuclei regulates energy balance in a sex-dependent manner.</a> Endocrinology. 162 (1), 1-16 (2021).</li><li>Liu, H., 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=Defining+vitamin+D+receptor+expression+in+the+brain+using+a+novel+VDR(Cre)+mouse.">Defining vitamin D receptor expression in the brain using a novel VDR(Cre) mouse.</a> Journal of Comparative Neurology. 529 (9), 2362-2375 (2020).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+animal+perfusion+fixation+for+rodents.">Whole animal perfusion fixation for rodents.</a> Journal of Visualized Experiments: JoVE. (65), e3564 (2012).</li><li>Whittington, N. C., Wray, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+red+blood+cell+autofluorescence+for+immunocytochemistry+on+fixed+embryonic+mouse+tissue.">Suppression of red blood cell autofluorescence for immunocytochemistry on fixed embryonic mouse tissue.</a> Current Protocols in Neuroscience. 81 (1), 2-28 (2017).</li><li>Zeller, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fixation,+embedding,+and+sectioning+of+tissues,+embryos,+and+single+cells.">Fixation, embedding, and sectioning of tissues, embryos, and single cells.</a> Current Protocols in Pharmacology. , (2001).</li><li>Potts, E. M., Coppotelli, G., Ross, J. 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(162), e61622 (2020).</li><li>He, 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=A+small+potassium+current+in+AgRP/NPY+neurons+regulates+feeding+behavior+and+energy+metabolism.">A small potassium current in AgRP/NPY neurons regulates feeding behavior and energy metabolism.</a> Cell Reports. 17 (7), 1807-1818 (2016).</li><li>Xu, P., 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=Activation+of+serotonin+2C+receptors+in+dopamine+neurons+inhibits+binge-like+eating+in+mice.">Activation of serotonin 2C receptors in dopamine neurons inhibits binge-like eating in mice.</a> Biololgical Psychiatry. 81 (9), 737-747 (2017).</li></ol>

This protocol provides an established method for neuroanatomical studies of the mouse brain, including perfusion, tissue sectioning, free-floating immunostaining, tissue mounting, and imaging. However, a few key details essential for consistent and reliable results must be optimized.
The quality of perfusion is critical for successful staining. Staining results might be affected if blood remains in the brain, given that blood cells (e.g., red blood cells) can generate an artificial &#39;positi...

The prevalence of obesity and associated comorbidities has reached epidemic levels, causing a tremendous socioeconomic burden1,2. Various mouse models have been developed to better understand the biological processes responsible for obesity3,4. Because central mechanisms are important for the regulation of energy homeostasis in these animal models, neuroanatomical studies of mouse brains have become a necessary technique in this field. However, the quality, reliability, and reproducibility of brain histology techniques vary considerably among laboratories and even researchers within the same laboratory for various reasons (e.g., antibodies, tissues, treatments, species, research objectives). Therefore, it is necessary to establish a general protocol for histological studies of the mouse brain, including perfusion, brain sectioning, free-floating immunostaining, tissue mounting, and imaging. Meanwhile, beginners can quickly learn, master, and adjust this protocol to satisfy their individual needs.
Immunohistochemical staining is an established method that has been used extensively to visualize specific cell types, mRNAs, and proteins in a variety of tissues (e.g., brain and peripheral tissues)5,6. More specifically, an antigen of interest can be labeled by a specific primary antibody and a corresponding secondary antibody linked to an enzyme (e.g., chromogenic immunohistochemistry) or a fluorescent dye (fluorescein isothiocyanate)6. As an example of the utility of these techniques, &#946;-endorphin [one peptide encoded by pro-opiomelanocortin (POMC)] and c-fos (a marker of neuronal activity) were stained in the arcuate nucleus. Deletion of tryptophan hydroxylase 2 (an enzyme integral to serotonin synthesis) in the dorsal raphe nucleus was shown to decrease c-fos expression in POMC neurons in the arcuate nucleus7. In addition, the distribution of vitamin D receptor mRNA was mapped in the mouse brain via in situ hybridization (RNAscope)8. This paper presents a reliable and efficient method with a step-by-step workflow for free-floating immunostaining, aiming to improve the quality and reproducibility of histological studies of the mouse brain.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alexa Flour 594 donkey anti-rabbit IgG (H+L)</td>
			<td>Invitrogen</td>
			<td>A21207</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;30% Sucrose</td>
			<td>VWR</td>
			<td>470302</td>
			<td>30 g Sucrose dissoved into 100 mL of PBS</td>
		</tr>
		<tr>
			<td>&#160;Neutral Buffered Formalin</td>
			<td>VWR</td>
			<td>16004-128</td>
			<td>10%, 25 &#176;C, pH 6.8-7.2</td>
		</tr>
		<tr>
			<td>1 mL Sub-Q Syringe</td>
			<td>BD</td>
			<td>309597</td>
			<td></td>
		</tr>
		<tr>
			<td>48 Well Cell Culture Plate</td>
			<td>Corning</td>
			<td>3548</td>
			<td></td>
		</tr>
		<tr>
			<td>6 Well Cell Culture Plate</td>
			<td>Corning</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>Antifading mounting media with DAPI</td>
			<td>Vector Laboratories</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr>
			<td>Autoclavable plastic desiccator</td>
			<td>Thermo Scientific Nalgene</td>
			<td>5315-0150</td>
			<td></td>
		</tr>
		<tr>
			<td>AVP antibody</td>
			<td>Phoenix Pharmaceuticals</td>
			<td>H-065-07</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Strainer</td>
			<td>Corning</td>
			<td>431752</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryoprotectant buffer</td>
			<td>User preference</td>
			<td>Not applicable</td>
			<td>20% glycerol, 30% ethylene glycol, and 50% PBS</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Covetrus</td>
			<td>11695-6777-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Leica DFC310FX microscope</td>
			<td>Leica</td>
			<td>Not applicable</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Slide Boxes (50-place)</td>
			<td>VWR</td>
			<td>Not applicable</td>
			<td></td>
		</tr>
		<tr>
			<td>PBT</td>
			<td>User preference</td>
			<td>Not applicable</td>
			<td>2.5 mL of Triton X-100 dissolved into 1000 mL of PBS</td>
		</tr>
		<tr>
			<td>Perfusion two automated Perfusion System</td>
			<td>Leica</td>
			<td>39471005</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline (PBS) 20x</td>
			<td>VWR</td>
			<td>VWRVE703-1L</td>
			<td>25 &#176;C, pH 7.3-7.5, 1x composition:137 mM NaCl, 2.7 mM KCl, 9.8 mM Phosphate buffer</td>
		</tr>
		<tr>
			<td>Slideing Microtome Microm HM450</td>
			<td>ThermoFisher</td>
			<td>Microm HM450</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>RICCA Chemical</td>
			<td>7220-32</td>
			<td>0.9%, 25 &#176;C, pH 7.4</td>
		</tr>
		<tr>
			<td>Streptavidin Protein, DyLight 488</td>
			<td>ThermoFisher</td>
			<td>#21832</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>089k01921</td>
			<td></td>
		</tr>
		<tr>
			<td>WFA antibody</td>
			<td>Sigma-Aldrich</td>
			<td>L1516</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss Axio Z1 Scanner</td>
			<td>Zeiss</td>
			<td>Not applicable</td>
			<td></td>
		</tr>
		<tr>
			<td>Zen 3.1 software</td>
			<td></td>
			<td></td>
			<td>scanner software</td>
		</tr>
	</tbody>
</table>

free-floating immunostaining of mouse brains

Immunohistochemical staining of mouse brains is a routine technique commonly used in neuroscience to investigate central mechanisms underlying the regulation of energy metabolism and other neurobiological processes. However, the quality, reliability, and reproducibility of brain histology results may vary among laboratories. For each staining experiment, it is necessary to optimize the key procedures based on differences in species, tissues, targeted proteins, and the working conditions of the reagents. This paper demonstrates a reliable workflow in detail, including intra-aortic perfusion, brain sectioning, free-floating immunostaining, tissue mounting, and imaging, which can be followed easily by researchers in this field.
Also discussed are how to modify these procedures to satisfy the individual needs of researchers. To illustrate the reliability and efficiency of this protocol, perineuronal nets were stained with biotin-labeled Wisteria florbunda agglutinin (WFA) and arginine vasopressin (AVP) with an anti-AVP antibody in the mouse brain. Finally, the critical details for the entire procedure have been addressed, and the advantages of this protocol compared to those of other protocols. Taken together, this paper presents an optimized protocol for free-floating immunostaining of mouse brain tissue. Following this protocol makes this process easier for both junior and senior scientists to improve the quality, reliability, and reproducibility of immunostaining studies.

The flow chart of this protocol is briefly illustrated in Figure 1. This laboratory&#39;s cryosectioning procedure is demonstrated in Figure 2A, in which 5 brain samples were sectioned simultaneously. The mounting of brain sections is shown in Figure 2B, and a fully mounted slide with brain sections is illustrated in Figure 2C. In Figure 3, representative fluorescence immun...

Watch this Scientific Journal Video about Free-floating Immunostaining of Mouse Brains at JoVE.com

Free-floating Immunostaining of Mouse Brains

This protocol describes an efficient and reproducible approach for mouse brain histological studies, including perfusion, brain sectioning, free-floating immunostaining, tissue mounting, and imaging.

Immunohistochemical staining of mouse brains is a routine technique commonly used in neuroscience to investigate central mechanisms underlying the ...

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