Name: dural stimulation and periorbital von frey testing in mice as a preclinical model of headache
Uploaded: 2021-07-29T15:00:00
Description: Watch this Scientific Journal Video about Dural Stimulation and Periorbital von Frey Testing in Mice As a Preclinical Model of Headache at JoVE.com

This study was supported by the National Institutes of Health (NS104200 and NS072204 to GD).

All procedures were conducted with prior approval of the institutional Animal Care and Use Committee at the University of Texas at Dallas. ICR (CD-1) (30-35 g) and C57/BL6 (25-30 g) mice aged 6-8 weeks were used in this study.
1. Dural infuser
<ol>
	<li>Create the mouse infusers/injectors by modifying a commercially available internal cannula and infuser for unilateral injections with a non-metallic fused silica plastic cap that is adjustable and inserts into/extends below a 28 G guide cannu...

<ol>
	<li>GBD 2016 Disease and Injury Incidence and Prevalence Collaborators. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global,+regional,+and+national+incidence,+prevalence,+and+years+lived+with+disability+for+328+diseases+and+injuries+for+195+countries,+1990-2016:+a+systematic+analysis+for+the+Global+Burden+of+Disease+Study+2016.">Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016.</a> Lancet. 390 (10100), 1211-1259 (2017).</li><li>Woldeamanuel, Y. W., Cowan, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Migraine+affects+1+in+10+people+worldwide+featuring+recent+rise:+A+systematic+review+and+meta-analysis+of+community-based+studies+involving+6+million+participants.">Migraine affects 1 in 10 people worldwide featuring recent rise: A systematic review and meta-analysis of community-based studies involving 6 million participants.</a> Journal of the Neurological Sciences. 372, 307-315 (2017).</li><li>Burch, R. C., Loder, S., Loder, E., Smitherman, T. 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+prevalence+and+burden+of+migraine+and+severe+headache+in+the+United+States:+updated+statistics+from+government+health+surveillance+studies.">The prevalence and burden of migraine and severe headache in the United States: updated statistics from government health surveillance studies.</a> Headache. 55 (1), 21-34 (2015).</li><li>Ashina, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Migraine.">Migraine.</a> New England Journal of Medicine. 383 (19), 1866-1876 (2020).</li><li>Ashina, 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=Migraine:+integrated+approaches+to+clinical+management+and+emerging+treatments.">Migraine: integrated approaches to clinical management and emerging treatments.</a> Lancet. 397 (10283), 1505-1518 (2021).</li><li>Jacobs, B., Dussor, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurovascular+contributions+to+migraine:+Moving+beyond+vasodilation.">Neurovascular contributions to migraine: Moving beyond vasodilation.</a> Neuroscience. 338, 130-144 (2016).</li><li>Koyuncu Irmak, D., Kilinc, E., Tore, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shared+Fate+of+Meningeal+Mast+Cells+and+Sensory+Neurons+in+Migraine.">Shared Fate of Meningeal Mast Cells and Sensory Neurons in Migraine.</a> Frontiers in Cellular Neuroscience. 13, 136 (2019).</li><li>Levy, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Migraine+pain,+meningeal+inflammation,+and+mast+cells.">Migraine pain, meningeal inflammation, and mast cells.</a> Current Pain and Headache Reports. 13 (3), 237-240 (2009).</li><li>Levy, D., Labastida-Ramirez, A., MaassenVanDenBrink, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+understanding+of+meningeal+and+cerebral+vascular+function+underlying+migraine+headache.">Current understanding of meningeal and cerebral vascular function underlying migraine headache.</a> Cephalalgia. 39 (13), 1606-1622 (2019).</li><li>Phebus, L. A., Johnson, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dural+inflammation+model+of+migraine+pain.">Dural inflammation model of migraine pain.</a> Current Protocols in Neuroscience. , (2001).</li><li>Fried, N. T., Maxwell, C. R., Elliott, M. B., Oshinsky, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Region-specific+disruption+of+the+blood-brain+barrier+following+repeated+inflammatory+dural+stimulation+in+a+rat+model+of+chronic+trigeminal+allodynia.">Region-specific disruption of the blood-brain barrier following repeated inflammatory dural stimulation in a rat model of chronic trigeminal allodynia.</a> Cephalalgia. 38 (4), 674-689 (2018).</li><li>Avona, 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=Dural+calcitonin+gene-related+peptide+produces+female-specific+responses+in+rodent+migraine+models.">Dural calcitonin gene-related peptide produces female-specific responses in rodent migraine models.</a> The Journal of Neuroscience. 39 (22), 4323-4331 (2019).</li><li>Burgos-Vega, C. C., 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=Non-invasive+dural+stimulation+in+mice:+A+novel+preclinical+model+of+migraine.">Non-invasive dural stimulation in mice: A novel preclinical model of migraine.</a> Cephalalgia. 39 (1), 123-134 (2019).</li><li>Avona, 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=Meningeal+CGRP-Prolactin+interaction+evokes+female-specific+migraine+behavior.">Meningeal CGRP-Prolactin interaction evokes female-specific migraine behavior.</a> Annals of Neurology. 89 (6), 1129-1144 (2021).</li><li>Deuis, J. R., Dvorakova, L. S., Vetter, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+used+to+evaluate+pain+behaviors+in+rodents.">Methods used to evaluate pain behaviors in rodents.</a> Frontiers in Molecular Neuroscience. 10, 284 (2017).</li><li>Lipton, R. B., 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=Cutaneous+allodynia+in+the+migraine+population.">Cutaneous allodynia in the migraine population.</a> Annals of Neurology. 63 (2), 148-158 (2008).</li><li>Goadsby, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Migraine,+allodynia,+sensitisation+and+all+of+that.">Migraine, allodynia, sensitisation and all of that.</a> European Neurology. 53, 10-16 (2005).</li><li>Langford, D. 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=Coding+of+facial+expressions+of+pain+in+the+laboratory+mouse.">Coding of facial expressions of pain in the laboratory mouse.</a> Nature Methods. 7 (6), 447-449 (2010).</li><li>Mogil, J. S., Pang, D. S. J., Silva Dutra, G. G., Chambers, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+and+use+of+facial+grimace+scales+for+pain+measurement+in+animals.">The development and use of facial grimace scales for pain measurement in animals.</a> Neuroscience &amp; Biobehavioral Reviews. 116, 480-493 (2020).</li><li>Vuralli, D., Wattiez, A. S., Russo, A. F., Bolay, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+and+cognitive+animal+models+in+headache+research.">Behavioral and cognitive animal models in headache research.</a> The Journal of Headache and Pain. 20 (1), 11 (2019).</li><li>Mason, B. N., 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=Induction+of+migraine-like+photophobic+behavior+in+mice+by+both+peripheral+and+central+CGRP+mechanisms.">Induction of migraine-like photophobic behavior in mice by both peripheral and central CGRP mechanisms.</a> The journal of Neuroscience. 37 (1), 204-216 (2017).</li><li>Dixon, W. J., Mood, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+obtaining+and+analyzing+sensitivity+data.">A method for obtaining and analyzing sensitivity data.</a> The Journal of the American Statistical Association. 43 (241), 109-126 (1948).</li><li>Dixon, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+up-and-down+method+for+small+samples.">The up-and-down method for small samples.</a> The Journal of the American Statistical Association. 60, (1965).</li><li>Bonin, R. P., Bories, C., De Koninck, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simplified+up-down+method+(SUDO)+for+measuring+mechanical+nociception+in+rodents+using+von+Frey+filaments.">A simplified up-down method (SUDO) for measuring mechanical nociception in rodents using von Frey filaments.</a> Molecular Pain. 10, 26 (2014).</li><li>Ramachandran, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurogenic+inflammation+and+its+role+in+migraine.">Neurogenic inflammation and its role in migraine.</a> Seminars in Immunopathology. 40 (3), 301-314 (2018).</li><li>Edvinsson, L., Haanes, K. A., Warfvinge, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+inflammation+have+a+role+in+migraine.">Does inflammation have a role in migraine.</a> Nature Reviews Neurology. 15 (8), 483-490 (2019).</li><li>Stokely, M. E., Orr, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+effects+of+calvarial+damage+on+dural+mast+cells,+pial+vascular+permeability,+and+cerebral+cortical+histamine+levels+in+rats+and+mice.">Acute effects of calvarial damage on dural mast cells, pial vascular permeability, and cerebral cortical histamine levels in rats and mice.</a> Journal of Neurotrauma. 25 (1), 52-61 (2008).</li><li>Theoharides, T. C., Donelan, J., Kandere-Grzybowska, K., Konstantinidou, 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+role+of+mast+cells+in+migraine+pathophysiology.">The role of mast cells in migraine pathophysiology.</a> Brain Research Reviews. 49 (1), 65-76 (2005).</li><li>Conti, 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=Progression+in+migraine:+Role+of+mast+cells+and+pro-inflammatory+and+anti-inflammatory+cytokines.">Progression in migraine: Role of mast cells and pro-inflammatory and anti-inflammatory cytokines.</a> European Journal of Pharmacology. 844, 87-94 (2019).</li><li>Rea, B. 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=Peripherally+administered+calcitonin+gene-related+peptide+induces+spontaneous+pain+in+mice:+implications+for+migraine.">Peripherally administered calcitonin gene-related peptide induces spontaneous pain in mice: implications for migraine.</a> Pain. 159 (11), 2306-2317 (2018).</li></ol>

Maladaptive changes in the local nociceptive system in the dura are considered a key contributor to the headache phase of migraine attacks despite a lack of tissue injury25,26. Here the study presents a method whereby minimally invasive stimulation of the dura can induce facial tactile hypersensitivity. Elucidating the mechanisms and events involved in dural nociceptor activation without causing damage to the cranium and tissues may more accurately reflect migrai...

Migraine pain remains a major public health issue worldwide. The World Health Organization ranks it as the sixth-most prevalent disease in the world, afflicting just under 15% of the Earth&#39;s population1 and causing a substantial socioeconomic burden on society2,3. Treatment options and their efficacy have been suboptimal and only provide symptomatic relief and do not significantly modify pathophysiological events that underly migraine occurrence4,5. The lack of treatment success is likely due to migraine being a multifactorial disorder whose pathology is poorly understood, leading to a limited number of therapeutic targets. Migraine is also challenging to fully capture in animal models, especially given that migraine diagnosis is made based on verbal communication with patients who describe their experience with migraine hallmarks such as aura, headache, photophobia, and allodynia. Notwithstanding, it is important to note that recent advances in migraine treatments are currently outperforming treatments for many neurological conditions that have been well validated by preclinical models. For instance, monoclonal antibodies and small molecules that target calcitonin gene-related peptide, or its receptor have been very successful in improving the quality of life of migraine sufferers and can potentially transform the clinical management of migraine. While there has been advancement in understanding this disorder, there continues to be much yet to be elucidated.
Based on preclinical animal models and human studies, it is widely accepted that migraine headaches are initiated by aberrant activation of nociceptive fibers within the meninges that signal through the trigeminal and upper cervical dorsal-root ganglia6,7,8,9,10. Despite this theory, many studies still use systemic administration of drugs to understand underlying contributing mechanisms in migraine. While systemic dosing of drugs has substantially strengthened our understanding, these findings do not directly assess whether local actions within the target tissue of interest play a role in migraine. Conversely, several studies have taken an approach to stimulate the dura; however, these experiments require cannula implantation via an invasive craniotomy and extended recovery times11,12. Because of these limitations, we developed a minimally invasive approach to locally stimulate the dura where the lack of a craniotomy eliminates post-surgical recovery and allows for immediate testing in awake animals12,13,14. These injections are performed under light isoflurane anesthesia and administered at the junction of the sagittal and lambdoid sutures in mice.
Several approaches have been developed to evaluate nociceptive behavioral responses in rodents15. Cutaneous allodynia has been reported in approximately 80% of migraine sufferers16,17 and represents a potential translational endpoint for use in rodents. In preclinical models, the application of von Frey filaments to the plantar region of the rodent paw has been used to assess pain behaviors in preclinical migraine models. The primary limitation of this approach is that it does not test the cephalic region. Facial grimace scoring has been used to capture pain behaviors in rodents by analyzing facial expressions after induction of pain stimuli18,19. However, its limitations include only capturing responses to acute stimuli and not chronic orofacial pain conditions. Facial grooming and decreased rearing are also considered outputs of behavioral responses in preclinical models of migraine20,21. Limitations of the former include difficulty in differentiating pain responses from normal routine grooming and other sensations such as itch. In the case of the latter, rearing behaviors typically decrease quickly after the introduction of rodents to novel environments. Although each of these behavioral endpoints is valuable in the understanding of various mechanisms that contribute to pain conditions, there is a critical need for preclinical models of pain disorders such as migraine to include endpoints that specifically capture cephalic hypersensitivity responses. Assessing tactile hypersensitivity of the periorbital skin following dural stimulation is a method that may provide better insight into mechanisms contributing to migraines where sensory symptoms are predominantly cephalic in nature. Here, we describe a method to administer substances onto the mouse dura as a preclinical model of migraine. Following dural application, we also present a detailed method for testing periorbital tactile hypersensitivity using calibrated von Frey filaments applied in the Dixon up-down method.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4 oz Hot Paper Cups</td>
			<td>Choice Paper Company</td>
			<td>5004W</td>
			<td>https://www.webstaurantstore.com/choice-4-oz-white-poly-paper-hot-cup-case/5004W.html</td>
		</tr>
		<tr>
			<td>Absorbent Underpads</td>
			<td>Fisherbrand</td>
			<td>14-206-65</td>
			<td>https://www.fishersci.com/shop/products/fisherbrand-absorbent-underpads-8/p-306048</td>
		</tr>
		<tr>
			<td>C313I/SPC Internal 28 G cannula</td>
			<td>P1 Technologies (formerly Plastics One)</td>
			<td>8IC313ISPCXC</td>
			<td>I.D. 18 mm, O.D. 35 mm</td>
		</tr>
		<tr>
			<td>Gastight Model 1701 SN Syringes</td>
			<td>Hamilton</td>
			<td>80008</td>
			<td>https://www.hamiltoncompany.com/laboratory-products/syringes/80008</td>
		</tr>
		<tr>
			<td>Ismatec Pump Tubing, 0.19 mm</td>
			<td>Cole-Palmer</td>
			<td>EW-96460-10</td>
			<td>https://www.coleparmer.com/i/ismatec-pump-tubing-2-stop-tygon-s3-e-lab-0-19-mm-id-12-pk/9646010</td>
		</tr>
		<tr>
			<td>Stand with chicken wire</td>
			<td>Custom</td>
			<td></td>
			<td>The galvanized steel chicken wire dimensions are 0.25 in. x 19-gauge</td>
		</tr>
		<tr>
			<td>Testing Rack with individual&#160; Chambers</td>
			<td>Custom</td>
			<td></td>
			<td>Each chamber should have a division between each mouse and lids to contain the mouse. The chambers should also be large enough to hold a 4 oz. paper cup.</td>
		</tr>
		<tr>
			<td>von Frey Filaments</td>
			<td>Touch test/Stoelting</td>
			<td>58011</td>
			<td>https://www.stoeltingco.com/touch-test.html</td>
		</tr>
	</tbody>
</table>

dural stimulation and periorbital von frey testing in mice as a preclinical model of headache

The cranial meninges, comprised of the dura mater, arachnoid, and pia mater, are thought to primarily serve structural functions for the nervous system. For example, they protect the brain from the skull and anchor/organize the vascular and neuronal supply of the cortex. However, the meninges are also implicated in nervous system disorders such as migraine, where the pain experienced during a migraine is attributed to local sterile inflammation and subsequent activation of local nociceptive afferents. Of the layers in the meninges, the dura mater is of particular interest in the pathophysiology of migraines. It is highly vascularized, harbors local nociceptive neurons, and is home to a diverse array of resident cells such as immune cells. Subtle changes in the local meningeal microenvironment may lead to activation and sensitization of dural perivascular nociceptors, thus leading to migraine pain. Studies have sought to address how dural afferents become activated/sensitized by using either in vivo electrophysiology, imaging techniques, or behavioral models, but these commonly require very invasive surgeries. This protocol presents a method for comparatively non-invasive application of compounds on the dura mater in mice and a suitable method for measuring headache-like tactile sensitivity using periorbital von Frey testing following dural stimulation. This method maintains the integrity of the dura and skull and reduces confounding effects from invasive techniques by injecting substances through a 0.65 mm modified cannula at the junction of unfused sagittal and lambdoid sutures. This preclinical model will allow researchers to investigate a wide range of dural stimuli and their role in the pathological progression of migraine, such as nociceptor activation, immune cell activation, vascular changes, and pain behaviors, all while maintaining injury-free conditions to the skull and meninges.

This injection method is used to administer stimuli onto the dura of mice so that subsequent behavioral testing may occur. The most common behavioral output measured with this model is cutaneous facial hypersensitivity assessed via von Frey12,13,14. Here we show how this model can be used to assess potential sex-specific contributions to migraine pathology (Figure 3).
Thi...

Watch this Scientific Journal Video about Dural Stimulation and Periorbital von Frey Testing in Mice As a Preclinical Model of Headache at JoVE.com

Dural Stimulation and Periorbital von Frey Testing in Mice As a Preclinical Model of Headache

The most notable symptom of migraine is severe head pain, and it is hypothesized that this is mediated by sensory neurons innervating the meninges. Here, we present a method to locally apply substances to the dura in a minimally invasive manner while using facial hypersensitivity as an output.

The cranial meninges, comprised of the dura mater, arachnoid, and pia mater, are thought to primarily serve structural functions for the nervous system.  ...

What events occur within the meninges that contribute to headache in the absence of tissue injury? Unlike prior use of dural stimulation models in rats, it allows the use of the extensive catalog of genetically modified mice. The primary struggle would be locating the intersection of the lambdoidal and sagittal sutures by palpating the skull with the injector.To begin, create the mouse infusers by modifying a commercially available internal cannula and infuser with a fused silica plastic cap which is adjustable and inserts into a 28-gauge guide cannula. Use a caliper to adjust the fused silica plastic cap on the infuser without bending the infuser. Adjust the infuser to a length of 6 millimeters measured from the tip of the infuser to the edge of the silica plastic cap.Perform pilot injections for other mouse strains and adjust the length to precisely inject in dura mater. Then, attach the long end of the infuser to plastic tubing of eight inches or more to hold five microliters volume. Insert the tube while ensuring full coverage of the metal part and the top of the plastic stopper located on the infuser to prevent air bubbles from accumulating in the line.Next, fill the microsyringe and attach the other end of the tubing to a 10-microliter glass microsyringe, ensuring tight sealing over the metal part of the syringe. Then, backfill the syringe with five microliters of PBS or synthetic interstitial fluid or other vehicles of choice to prevent air bubble formation. If needed, flood the line with the vehicle to dissipate preformed bubbles.Alternatively, pre-fill the syringe, and after connecting, push the fluid through the connected line. Once the vehicle-filled line is working efficiently, load five microliters of the solution into the Hamilton syringe. Once the mouse is completely anesthetized, apply sterile ophthalmic ointment to the eyes and shave the head of the animal, then disinfect the skin with povidone iodine and ethanol.Steady the head of the animal with one hand and hold the infuser with the drug-loaded syringe in the other. Then, using an infuser, carefully probe, locate, and verify the junction of the sagittal and lambdoidal sutures on the skull of the mouse. Once the suture is located and the infuser is in place, slowly and gently wiggle the in infuser back and forth until the in infuser pierces through the skin and drops down into the junction all the way up to the plastic stopper, ensuring the insertion of the entire 6-millimeter infuser tip into the junction.Then, slowly push the plunger of the syringe to expel the five microliters of fluid into the dura mater. On the testing day, post-acclimation to the room, remove one mouse along with the cup from the respective chamber. Maintain the cup in the horizontal position for evenly distributed body weight, as the unequal weight distribution may alter or prevent animals'response.Place the cup with the mouse on an absorbent pad kept on the table below the testing rack. Then, for periorbital von Frey testing, place the 07-gram von Frey filament at the center of the face in between the eyes and apply enough pressure on the filament to cause the von Frey hair to bend into a C-shaped formation. Maintain filament contact for about three to five seconds or until the mouse swipes away the filament using the head or paws.To follow the Dixon up-down method, apply the next lower-weight filament if the mouse responds to the filament, otherwise, apply higher-weight filament. The procedure was used to examine the effects of dural prolactin on mechanically evoked facial hypersensitivity. The results of the study demonstrated significantly reduced facial withdrawal thresholds in female ICR mice in response to five micrograms of dural prolactin.A ten-fold lower dose of 5 micrograms of prolactin also showed reduced facial withdrawal thresholds, similar to a high dose of prolactin. The prolactin injections produced spontaneous pain-related behaviors, which were assessed via grimace. Dural 5 micrograms of prolactin caused significant grimacing in female mice and further demonstrated a clear role for dural prolactin in female migraine-like behaviors Behavioral testing using von Frey filaments or facial grimace to determine whether the stimulus, in the absence of injury, causes a headache response.This technique can now be used to investigate inflammatory based mechanisms in the meninges without concern over caveats that are caused by craniotomies and the subsequent inflammation.

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Neuroscience

Combining Transcranial Magnetic Stimulation and fMRI to Examine the Default Mode Network

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful rest."1,2,3 It is thought the default mode network corresponds to self-referential or "internal mentation".2,3
It has been hypothesized that, in humans, activity within the default mode network is correlated with certain pathologies (for instance, hyper-activation has been linked to schizophrenia 4,5,6 and autism spectrum disorders 7 whilst hypo-activation of the network has been linked to Alzheimer's and other neurodegenerative diseases 8). As such, noninvasive modulation of this network may represent a potential therapeutic intervention for a number of neurological and psychiatric pathologies linked to abnormal network activation. One possible tool to effect this modulation is Transcranial Magnetic Stimulation: a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability (either increasing or decreasing it) via the application of localized magnetic field pulses.9
In order to explore the default mode network's propensity towards and tolerance of modulation, we will be combining TMS (to the left inferior parietal lobe) with functional magnetic resonance imaging (fMRI). Through this article, we will examine the protocol and considerations necessary to successfully combine these two neuroscientific tools.

In this article, we examine the methodology and considerations relevant to the combination of TMS and fMRI to examine the effects of brain stimulation on the default network.

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful ...

TMS: Using the Theta-Burst Protocol to Explore Mechanism of Plasticity in Individuals with Fragile X Syndrome and Autism

Fragile X Syndrome (FXS), also known as Martin-Bell Syndrome, is a genetic abnormality found on the X chromosome.1,2 Individuals suffering from FXS display abnormalities in the expression of FMR1 - a protein required for typical, healthy neural development.3 Recent data has suggested that the loss of this protein can cause the cortex to be hyperexcitable thereby affecting overall patterns of neural plasticity.4,5
In addition, Fragile X shows a strong comorbidity with autism: in fact, 30% of children with FXS are diagnosed with autism, and 2 - 5% of autistic children suffer from FXS.6
Transcranial Magnetic Stimulation (a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability via the application of localized magnetic field pulses 7,8) represents a unique method of exploring plasticity and the manifestations of FXS within affected individuals. More specifically, Theta-Burst Stimulation (TBS), a specific stimulatory protocol shown to modulate cortical plasticity for a duration up to 30 minutes after stimulation cessation in healthy populations, has already proven an efficacious tool in the exploration of abnormal plasticity.9,10 
Recent studies have shown the effects of TBS last considerably longer in individuals on the autistic spectrum - up to 90 minutes.11 This extended effect-duration suggests an underlying abnormality in the brain's natural plasticity state in autistic individuals - similar to the hyperexcitability induced by Fragile X Syndrome.
In this experiment, utilizing single-pulse motor-evoked potentials (MEPs) as our benchmark, we will explore the effects of both intermittent and continuous TBS on cortical plasticity in individuals suffering from FXS and individuals on the Autistic Spectrum.

In this article, we examine the effects of Theta-Burst TMS stimulation on cortical plasticity in individuals suffering from Fragile X syndrome and individuals on the autistic spectrum.

Fragile X Syndrome (FXS), also known as Martin-Bell Syndrome, is a genetic abnormality found on the X chromosome.1,2 Individuals suffering from FXS ...

The NeuroStar TMS Device: Conducting the FDA Approved Protocol for Treatment of Depression

The Neuronetics NeuroStar Transcranial Magnetic Stimulation (TMS) System is a class II medical device that produces brief duration, pulsed magnetic fields. These rapidly alternating fields induce electrical currents within localized, targeted regions of the cortex which are associated with various physiological and functional brain changes.1,2,3
In 2007, O'Reardon et al., utilizing the NeuroStar device, published the results of an industry-sponsored, multisite, randomized, sham-stimulation controlled clinical trial in which 301 patients with major depression, who had previously failed to respond to at least one adequate antidepressant treatment trial, underwent either active or sham TMS over the left dorsolateral prefrontal cortex (DLPFC). The patients, who were medication-free at the time of the study, received TMS five times per week over 4-6 weeks.4
The results demonstrated that a sub-population of patients (those who were relatively less resistant to medication, having failed not more than two good pharmacologic trials) showed a statistically significant improvement on the Montgomery-Asberg Depression Scale (MADRS), the Hamilton Depression Rating Scale (HAMD), and various other outcome measures. In October 2008, supported by these and other similar results5,6,7, Neuronetics obtained the first and only Food and Drug Administration (FDA) approval for the clinical treatment of a specific form of medication-refractory depression using a TMS Therapy device (FDA approval K061053).
In this paper, we will explore the specified FDA approved NeuroStar depression treatment protocol (to be administered only under prescription and by a licensed medical profession in either an in- or outpatient setting).

In this article, we examine the methodology and considerations relevant to the FDA approved depression treatment protocol using the Neuronetics NeuroStar TMS device.

The Neuronetics NeuroStar Transcranial Magnetic Stimulation (TMS) System is a class II medical device that produces brief duration, pulsed magnetic ...

Electrode Positioning and Montage in Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a non-invasive and safe alternative to change cortical excitability2. The effects of one session of tDCS can last for several minutes, and its effects depend on polarity of stimulation, such as that cathodal stimulation induces a decrease in cortical excitability, and anodal stimulation induces an increase in cortical excitability that may last beyond the duration of stimulation6. These effects have been explored in cognitive neuroscience and also clinically in a variety of neuropsychiatric disorders &#x2013; especially when applied over several consecutive sessions4. One area that has been attracting attention of neuroscientists and clinicians is the use of tDCS for modulation of pain-related neural networks3,5. Modulation of two main cortical areas in pain research has been explored: primary motor cortex and dorsolateral prefrontal cortex7. Due to the critical role of electrode montage, in this article, we show different alternatives for electrode placement for tDCS clinical trials on pain; discussing advantages and disadvantages of each method of stimulation.

Transcranial direct current stimulation (tDCS) is an established technique to modulate cortical excitability1,2. It has been used as an investigative tool in neuroscience due to its effects on cortical plasticity, easy operation, and safe profile. One area that tDCS has been showing encouraging results is pain alleviation 3-5.

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a ...

Measuring Changes in Tactile Sensitivity in the Hind Paw of Mice Using an Electronic von Frey Apparatus

Measuring inflammation-induced changes in thresholds of hind paw withdrawal from mechanical pressure is a useful technique to assess changes in pain perception in rodents. Withdrawal thresholds can be measured first at baseline and then following drug, venom, injury, allergen,&#160;or otherwise evoked inflammation by applying an accurate force on very specific areas of the skin. An electronic von Frey apparatus allows precise assessment of mouse hind paw withdrawal thresholds that are not limited by the available filament sizes in contrast to classical von Frey measurements. The ease and rapidity of measurements allow for incorporation of assessment of tactile sensitivity outcomes in diverse models of rapid-onset inflammatory and neuropathic pain as multiple measurements can be taken within a short time period. Experimental measurements for individual rodent subjects can be internally controlled against individual baseline responses and exclusion criteria easily established to standardize baseline responses within and across experimental groups. Thus, measurements using an electronic von Frey apparatus represent a useful modification of the well-established classical von Frey filament-based assays for rodent mechanical allodynia that may also be applied to other nonhuman mammalian models.

Electronic von Frey measurements are an effective and improved alternative to classical von Frey filaments, as they allow rapid and precise measurement of changes in rodent mechanical withdrawal thresholds to continuously applied pressure stimuli before and after an inflammatory event.

Measuring inflammation-induced changes in thresholds of hind paw withdrawal from mechanical pressure is a useful technique to assess changes in pain ...

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems.

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

We describe a protocol for in vivo labeling of olfactory sensory neurons by electroporation and subsequent confocal laser-scanning or multiphoton microscopy to visualize neuronal morphology and its development over time.

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of ...

A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity.
Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 &#176;C to 5 &#176;C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above.
This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

The Cold Plantar Assay (CPA) measures cold responsiveness between 30 &#176;C and 5 &#176;C, and can also measure cold adaptation. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life.  The cold ...

Simultaneous ex vivo Functional Testing of Two Retinas by in vivo Electroretinogram System

An In vivo electroretinogram (ERG) signal is composed of several overlapping components originating from different retinal cell types, as well as noise from extra-retinal sources. Ex vivo ERG provides an efficient method to dissect the function of retinal cells directly from an intact isolated retina of animals or donor eyes. In addition, ex vivo ERG can be used to test the efficacy and safety of potential therapeutic agents on retina tissue from animals or humans. We show here how commercially available in vivo ERG systems can be used to conduct ex vivo ERG recordings from isolated mouse retinas. We combine the light stimulation, electronic and heating units of a standard in vivo system with custom-designed specimen holder, gravity-controlled perfusion system and electromagnetic noise shielding to record low-noise ex vivo ERG signals simultaneously from two retinas with the acquisition software included in commercial in vivo systems. Further, we demonstrate how to use this method in combination with pharmacological treatments that remove specific ERG components in order to dissect the function of certain retinal cell types.

Simultaneous ex vivo Functional Testing of Two Retinas by in vivo Electroretinogram System

Ex vivo ERG can be used to record electrical activity of retinal cells directly from isolated intact retinas of animals or humans. We demonstrate here how common in vivo ERG systems can be adapted for ex vivo ERG recordings in order to dissect the electrical activity of retinal cells.

An In vivo electroretinogram (ERG) signal is composed of several overlapping components originating from different retinal cell types, as well as noise ...

An In Ovo Model for Testing Insulin-mimetic Compounds

Elevated blood glucose levels in type 2 diabetes mellitus (T2DM), a complex and multifactorial metabolic disease, are caused by insulin resistance and &#946;-cell failure. Various strategies, including the injection of insulin or the usage of insulin-sensitizing drugs, were pursued to treat T2DM or at least reduce the symptoms. In addition, the application of herbal compounds has attracted increasing attention. Thus, it is necessary to find efficient test systems to identify and characterize insulin-mimetic compounds. Here we developed a modified chick embryo model, which enables testing of synthetic compounds and herbal extracts with insulin-mimetic properties. Using a fluorescence microscopy-based primary screen, which quantifies the translocation of Glucose transporter 4 (Glut4) to the plasma membrane, we were able to identify compounds, mainly herbal extracts, which lead to an increase of intracellular glucose concentrations in adipocytes. However, the efficacy of these substances requires further verification in a living organism. Thus, we used an in-ovo approach to identify their blood glucose-reducing properties. The approval by an ethics committee is not needed since the use of chicken embryos during the first two-thirds of embryonic development is not considered an animal experiment. Here, the application of this model is described in detail.

An In Ovo Model for Testing Insulin-mimetic Compounds

In this study, we describe an in-ovo system as a promising tool to test insulin-mimetic compounds in a living organism. The main advantages include adequate throughput rates and acceptable costs, which enable the identification of phytochemicals with insulin-mimetic properties.

Elevated blood glucose levels in type 2 diabetes mellitus (T2DM), a complex and multifactorial metabolic disease, are caused by insulin resistance and ...

Transcranial Direct Current Stimulation (tDCS) in Mice

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique proposed as an alternative or complementary treatment for several neuropsychiatric diseases. The biological effects of tDCS are not fully understood, which is in part explained due to the difficulty in obtaining human brain tissue. This protocol describes a tDCS mouse model that uses a chronically implanted electrode allowing the study of the long-lasting biological effects of tDCS. In this experimental model, tDCS changes the cortical gene expression and offers a prominent contribution to the understanding of the rationale for its therapeutic use.

Transcranial Direct Current Stimulation tDCS in Mice

Transcranial direct current stimulation (tDCS) is a therapeutic technique proposed to treat psychiatric diseases. An animal model is essential for understanding the specific biological alterations evoked by tDCS. This protocol describes a tDCS mouse model that uses a chronically implanted electrode.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique proposed as an alternative or complementary treatment for ...