Name: back mechanical sensitivity assessment in the rat for mechanistic investigation of chronic back pain
Uploaded: 2022-08-30T13:00:00
Description: Watch this Scientific Journal Video about Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain at JoVE.com

This work was supported by a grant from the Fondation Chiropratique du Qu&#233;bec and the Natural Sciences and Engineering Research Council of Canada (MP: grant #06659). The contribution of HK was supported by the Universit&#233; du Qu&#233;bec &#224; Trois-Rivi&#232;res (PAIR program). The contribution of BP was supported by the Fonds de recherche du Qu&#233;bec en Sant&#233; (FRQS) and the Fondation Chiropratique du Qu&#233;bec. The contribution of TP was supported by the Natural Sciences and Engineering Research Council of Canada. The contribution of NE and EK was supported by the Fondation Chiropratique du Qu&#233;bec. The contribution of MP was supported by the FRQS.

The experimental protocol was approved by the animal care committee of Universit&#233; du Qu&#233;bec &#224; Trois-Rivi&#232;res and conformed to the Guidelines of the Canadian Council on Animal Care and the Guidelines of the Committee for Research and Ethical Issues of the International Association for the Study of Pain (IASP). The present study used six male Wistar rats (body weight: 320-450 g; age: 18-22 weeks). The animals were obtained from a commercial source (see Table of Materials). Data from the...

<ol>
	<li>Hartvigsen, 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=What+low+back+pain+is+and+why+we+need+to+pay+attention.">What low back pain is and why we need to pay attention.</a> Lancet. 391 (10137), 2356-2367 (2018).</li><li>Manchikanti, L., Singh, V., Falco, F. J., Benyamin, R. M., Hirsch, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+low+back+pain+in+adults.">Epidemiology of low back pain in adults.</a> Neuromodulation. 17, 3-10 (2014).</li><li>Urits, I., 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=Low+back+pain,+a+comprehensive+review:+Pathophysiology,+diagnosis,+and+treatment.">Low back pain, a comprehensive review: Pathophysiology, diagnosis, and treatment.</a> Current Pain and Headache Reports. 23 (3), 23 (2019).</li><li>James, S. L., 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=Global,+regional,+and+national+incidence,+prevalence,+and+years+lived+with+disability+for+354+diseases+and+injuries+for+195+countries+and+territories,+1990-2017:+a+systematic+analysis+for+the+Global+Burden+of+Disease+Study+2017.">Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.</a> Lancet. 392 (10159), 1789-1858 (2018).</li><li>Hoy, D., 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+systematic+review+of+the+global+prevalence+of+low+back+pain.">A systematic review of the global prevalence of low back pain.</a> Arthritis &amp; Rheumatology. 64 (6), 2028-2037 (2012).</li><li>Shi, 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=Animal+models+for+studying+the+etiology+and+treatment+of+low+back+pain.">Animal models for studying the etiology and treatment of low back pain.</a> Journal of Orthopaedic Research. 36 (5), 1305-1312 (2018).</li><li>Olmarker, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Puncture+of+a+lumbar+intervertebral+disc+induces+changes+in+spontaneous+pain+behavior:+An+experimental+study+in+rats.">Puncture of a lumbar intervertebral disc induces changes in spontaneous pain behavior: An experimental study in rats.</a> Spine. 33 (8), 850-855 (2008).</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>Kawakami, 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=Pathomechanism+of+pain-related+behavior+produced+by+allografts+of+intervertebral+disc+in+the+rat.">Pathomechanism of pain-related behavior produced by allografts of intervertebral disc in the rat.</a> Spine. 21 (18), 2101-2107 (1996).</li><li>Hu, S. -. J., Xing, J. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+experimental+model+for+chronic+compression+of+dorsal+root+ganglion+produced+by+intervertebral+foramen+stenosis+in+the+rat.">An experimental model for chronic compression of dorsal root ganglion produced by intervertebral foramen stenosis in the rat.</a> Pain. 77 (1), 15-23 (1998).</li><li>Xie, W. R., 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=Robust+increase+of+cutaneous+sensitivity,+cytokine+production+and+sympathetic+sprouting+in+rats+with+localized+inflammatory+irritation+of+the+spinal+ganglia.">Robust increase of cutaneous sensitivity, cytokine production and sympathetic sprouting in rats with localized inflammatory irritation of the spinal ganglia.</a> Neuroscience. 142 (3), 809-822 (2006).</li><li>Arthritis and Rheumatism. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+new+animal+model+for+evaluation+and+treatment+of+back+pain+due+to+lumbar+facet+joint+osteoarthritis.">Characterization of a new animal model for evaluation and treatment of back pain due to lumbar facet joint osteoarthritis.</a> Arthritis and Rheumatism. 63 (10), 2966-2973 (2011).</li><li>Kobayashi, Y., Sekiguchi, M., Konno, S. -. I., Kikuchi, S. -. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+intramuscular+pressure+in+lumbar+paraspinal+muscles+and+low+back+pain:+Model+development+and+expression+of+substance+P+in+the+dorsal+root+ganglion.">Increased intramuscular pressure in lumbar paraspinal muscles and low back pain: Model development and expression of substance P in the dorsal root ganglion.</a> Spine. 35 (15), 1423-1428 (2010).</li><li>Touj, S., 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=Sympathetic+regulation+and+anterior+cingulate+cortex+volume+are+altered+in+a+rat+model+of+chronic+back+pain.">Sympathetic regulation and anterior cingulate cortex volume are altered in a rat model of chronic back pain.</a> Neuroscience. 352, 9-18 (2017).</li><li>Chaplan, S. R., Bach, F. W., Pogrel, J. W., Chung, J. M., Yaksh, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+assessment+of+tactile+allodynia+in+the+rat+paw.">Quantitative assessment of tactile allodynia in the rat paw.</a> Journal of Neuroscience Methods. 53 (1), 55-63 (1994).</li><li>Deuis, J. R., 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=Analgesic+effects+of+clinically+used+compounds+in+novel+mouse+models+of+polyneuropathy+induced+by+oxaliplatin+and+cisplatin.">Analgesic effects of clinically used compounds in novel mouse models of polyneuropathy induced by oxaliplatin and cisplatin.</a> Neuro-Oncology. 16 (10), 1324-1332 (2014).</li><li>Randall, L. O., Selitto, 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=A+method+for+measurement+of+analgesic+activity+on+inflamed+tissue.">A method for measurement of analgesic activity on inflamed tissue.</a> Archives Internationales de Pharmacodynamie et de Therapie. 111 (4), 409-419 (1957).</li><li>D'Amour, F. E., Smith, D. L. <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+determining+loss+of+pain+sensation.">A method for determining loss of pain sensation.</a> Journal of Pharmacology and Experimental Therapeutics. 72 (1), 74-79 (1941).</li><li>Woolfe, 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+evaluation+of+the+analgesic+actions+of+pethidine+hydrochlodide+(Demerol).">The evaluation of the analgesic actions of pethidine hydrochlodide (Demerol).</a> Journal of Pharmacology and Experimental Therapeutics. 80 (3), 300-307 (1944).</li><li>Hargreaves, K., Dubner, R., Brown, F., Flores, C., Joris, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+and+sensitive+method+for+measuring+thermal+nociception+in+cutaneous+hyperalgesia.">A new and sensitive method for measuring thermal nociception in cutaneous hyperalgesia.</a> Pain. 32 (1), 77-88 (1988).</li><li>Deuis, J. R., 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=The+thermal+probe+test:+A+novel+behavioral+assay+to+quantify+thermal+paw+withdrawal+thresholds+in+mice.">The thermal probe test: A novel behavioral assay to quantify thermal paw withdrawal thresholds in mice.</a> Temperature. 3 (2), 199-207 (2016).</li><li>Allchorne, A. J., Broom, D. C., Woolf, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+cold+pain,+cold+allodynia+and+cold+hyperalgesia+in+freely+behaving+rats.">Detection of cold pain, cold allodynia and cold hyperalgesia in freely behaving rats.</a> Molecular Pain. 1, 36 (2005).</li><li>Carlton, S. M., Lekan, H. A., Kim, S. H., Chung, 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=Behavioral+manifestations+of+an+experimental+model+for+peripheral+neuropathy+produced+by+spinal+nerve+ligation+in+the+primate.">Behavioral manifestations of an experimental model for peripheral neuropathy produced by spinal nerve ligation in the primate.</a> Pain. 56 (2), 155-166 (1994).</li><li>Brenner, D. S., Golden, J. P., Gereau, R. W. I. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+behavioral+assay+for+measuring+cold+sensation+in+mice.">A novel behavioral assay for measuring cold sensation in mice.</a> PLoS One. 7 (6), 39765 (2012).</li><li>Moqrich, 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=Impaired+thermosensation+in+mice+lacking+TRPV3,+a+heat+and+camphor+sensor+in+the+skin.">Impaired thermosensation in mice lacking TRPV3, a heat and camphor sensor in the skin.</a> Science. 307 (5714), 1468-1472 (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>Deacon, R. M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Burrowing+in+rodents:+a+sensitive+method+for+detecting+behavioral+dysfunction.">Burrowing in rodents: a sensitive method for detecting behavioral dysfunction.</a> Nature Protocols. 1 (1), 118-121 (2006).</li><li>Griffioen, M. 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=Evaluation+of+dynamic+weight+bearing+for+measuring+nonevoked+inflammatory+hyperalgesia+in+mice.">Evaluation of dynamic weight bearing for measuring nonevoked inflammatory hyperalgesia in mice.</a> Nursing Research. 64 (2), 81-87 (2015).</li><li>Brodkin, 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=Validation+and+implementation+of+a+novel+high-throughput+behavioral+phenotyping+instrument+for+mice.">Validation and implementation of a novel high-throughput behavioral phenotyping instrument for mice.</a> Journal of Neuroscience Methods. 224, 48-57 (2014).</li><li>Paquette, T., Eskandari, N., Leblond, H., Pich&#233;, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+neurovascular+coupling+is+preserved+despite+time+dependent+alterations+of+spinal+cord+blood+flow+responses+in+a+rat+model+of+chronic+back+pain:+implications+for+functional+spinal+cord+imaging.">Spinal neurovascular coupling is preserved despite time dependent alterations of spinal cord blood flow responses in a rat model of chronic back pain: implications for functional spinal cord imaging.</a> Pain. , (2022).</li><li>Tokunaga, R., 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=Attenuation+of+widespread+hypersensitivity+to+noxious+mechanical+stimuli+by+inhibition+of+GABAergic+neurons+of+the+right+amygdala+in+a+rat+model+of+chronic+back+pain.">Attenuation of widespread hypersensitivity to noxious mechanical stimuli by inhibition of GABAergic neurons of the right amygdala in a rat model of chronic back pain.</a> European Journal of Pain. 26 (4), 911-928 (2022).</li><li>Dixon, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+analysis+of+experimental+observations.">Efficient analysis of experimental observations.</a> Annual Review of Pharmacology and Toxicology. 20, 441-462 (1980).</li></ol>

Critical steps 
The BMS test is a simple method to assess mechanical sensitivity in the back of rats, either at one time point or repeatedly over days or weeks, when changes are expected to occur (pain models) or after pharmacological or non-pharmacological intervention. Critical issues of the method include the test cage, whose dimensions must ensure that the rat is comfortable but does not move too much. The animal&#39;s back must stay accessible through the mesh ceiling for reproducible mechanica...

Low back pain (LBP) is the leading cause of disability worldwide, which has dramatic personal, economic, and social consequences1,2,3,4. Every year, approximately 37% of the population is affected by LBP5. LBP usually resolves within a few weeks but recurs in 24%-33% of individuals, becoming chronic in 5%-10% of cases2. To understand the mechanisms and impacts of LBP as well as the effects of different therapeutic interventions, several animal models of LBP have been used, mimicking clinical conditions or some components of LBP6. These mouse and rat models can be classified in one or more of the following categories: (1) discogenic LBP7,8,, (2) radicular LBP8,9,10,11, (3) facet joint osteoarthritis12, and (4) muscle-induced LBP13,14. Since the pain cannot be measured directly in non-human species, numerous tests have been developed to quantify pain-like behaviors in these models8. These tests assess behaviors evoked by a noxious stimulus (mechanical force15,16,17, thermal stimulation18,19,20,21,22,23,24,25) or produced spontaneously26,27,28,29.
The methods using mechanical stimuli include the Von Frey test15,16 and the Randall-Selitto Test17. Methods using heat stimuli include the tail flick test18, hot plate test19, Hargreaves test20, and thermal probe test21. Methods using cold stimuli include the cold plate test22, acetone evaporation test23, and cold plantar assay24. Methods for spontaneous behaviors include the grimace scales26, burrowing27, weight-bearing and gait analysis28, as well as an automated behavioral analysis29. Despite these numerous available tests, none of them is designed specifically for back pain models.
The objective of this study is to lay down a simple and accessible test to assess mechanical sensitivity in the back of rats. The technique is largely based on the Von Frey test applied to the plantar surface of the hind paw15,16. The basic principle of the Von Frey test is to use a series of monofilaments to the region of interest, delivering constant pre-determined forces. A response is considered positive if the rat shows a nocifensive behavior. The mechanical threshold can then be calculated based on the filaments that evoked responses. In the present study, a simple and accessible method adapted from the Von Frey test is provided to determine mechanical sensitivity in the back of rats.

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	<tbody>
		<tr>
			<td>Aerrane (isoflurane, USP) - Veterinary Use Only</td>
			<td>Baxter</td>
			<td>NDC 10019-773-60</td>
			<td>Inhalation Anaesthetic ; DIN 02225875, for inducing anasthesia</td>
		</tr>
		<tr>
			<td>Complete Freund Adjuvant (CFA)</td>
			<td>Fisher Scientific</td>
			<td>#77140</td>
			<td>Water-in-oil emulsion of Complete Freund Adjuvant (CFA) with killed cells of Mycobacterium butyricum.</td>
		</tr>
		<tr>
			<td>Male Wistar Rats</td>
			<td>Charles River Laboratories</td>
			<td></td>
			<td>body weight: 320&#8211;450 g; age: 18-22 weeks.</td>
		</tr>
		<tr>
			<td>Penlon Sigma Delta Vaporizer</td>
			<td>Penlon</td>
			<td>990-VI5K-SVEEK</td>
			<td>Penlon Sigma Delta Vaporizer used for anasthesia</td>
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			<td>Sharpie Permanent Marker</td>
			<td>Sharpie</td>
			<td>BC23636</td>
			<td>Permanent Marker, Fine Point, Black</td>
		</tr>
		<tr>
			<td>Test cage</td>
			<td>Custom-made</td>
			<td></td>
			<td>Width: 20 cm;&#160; Length: 50 cm; Height from the bottom to the top: 40 cm; Height from the bottom mesh to the top of the cage: 7 cm; Wall thickness: 5 mm; Mesh: 1 mm wire with an 8 mm inter-wire distance&#160;&#160;&#160;</td>
		</tr>
		<tr>
			<td>Von Frey Filaments</td>
			<td>Aesthesio, Precise Tactile Sensory Evaluator</td>
			<td>514000-20C</td>
			<td>Filaments from 0.07 g to 26 g</td>
		</tr>
		<tr>
			<td>Wahl Professional Animal, ARCO Cordless Pet Clipper, Trimmer Grooming&#160;</td>
			<td>Wahl</td>
			<td>Kit #8786-1201</td>
			<td>Animal hair trimmer, for shaving purposes, zero blade&#160;</td>
		</tr>
	</tbody>
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back mechanical sensitivity assessment in the rat for mechanistic investigation of chronic back pain

Low back pain is the leading cause of disability worldwide, with dramatic personal, economic, and social consequences. To develop novel therapeutics, animal models are needed to examine the mechanisms and effectiveness of novel therapies from a translational perspective. Several rodent models of back pain are used in current investigations. Surprisingly, however, no standardized behavioral test was validated to assess mechanical sensitivity in back pain models. This is critical to confirm that animals with presumed back pain present local hypersensitivity to nociceptive stimuli, and to monitor sensitivity during interventions designed to relieve back pain. The objective of this study is to lay down a simple and accessible test to assess mechanical sensitivity in the back of rats. A test cage was fabricated specifically for this method; length x width x height: 50 x 20 x 7 cm, having a stainless-steel mesh on the top. This test cage allows the application of mechanical stimuli to the back. To perform the test, the back of the animal is shaved in the region of interest, and the test area is marked to repeat the test on different days, as needed. The mechanical threshold is determined with Von Frey filaments applied to the paraspinal muscles, utilizing the up-down method described previously. The positive responses include (1) muscle twitching, (2) arching (back extension), (3) rotation of the neck (4) scratching or licking the back, and (5) escaping. This behavioral test (Back Mechanical Sensitivity (BMS) test) is useful for mechanistic research with rodent models of back pain for the development of therapeutic interventions for the prevention and management of back pain.

The method was used in a previous study, in which full data and statistics were presented to compare back mechanical sensitivity between CFA and control rats30. Representative individual data (mean of left and right thresholds) from six rats included in the previous study are presented in Figure 3 and Table 1. At baseline, mechanical sensitivity was similar between groups. Intramuscular injection of CFA in the lumbar muscles caused a marked increase i...

Watch this Scientific Journal Video about Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain at JoVE.com

Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain

To develop novel therapeutic interventions for the prevention and management of back pain, animal models are required to examine the mechanisms and effectiveness of these therapies from a translational perspective. The present protocol describes the BMS test, a standardized method to assess back mechanical sensitivity in the rat.

Low back pain is the leading cause of disability worldwide, with dramatic personal, economic, and social consequences. To develop novel therapeutics, ...

This protocol is useful to test mechanical sensitivity in the back. It is particularly interesting for longitudinal designs in rat models of chronic back pain, for which the goal is to examine effectiveness of an intervention to decrease back sensitivity to noxious stimuli. The method is simple, accessible, and yields reproducible results in trained experimenters.It is largely based on the Von Frey test, which is commonly used to assess mechanical sensitivity at the hind paw. As for any other behavioral test, the experimenters should practice standardizing the application of the filaments, and until behaviors produced by mechanical stimuli are easily distinguished from other behaviors. The test is simple, otherwise, and there should be no major difficulty to use it.Demonstrating the procedure will be Nasim Eskandari, a PhD student from my laboratory. To induce chronic back pain in the rat, perform an intramuscular injection of Complete Freund's Adjuvant, or CFA, into the back muscles. Using a 27 gauge needle, inject 150 microliters of a ready-to-use water-in-oil emulsion of CFA into the paraspinal muscles unilaterally or bilaterally.Keep the needle in place for at least three minutes. Next, fabricate the test cage for two animals, comprising one chamber for each animal by mounting the two contiguous chambers on four 33-centimeter long plexiglass legs. Use transparent plexiglass for the walls of the chambers, and black plexiglass to separate chambers to prevent animals from seeing each other.Then make the floor and ceiling of the test cage using stainless steel mesh made of one-millimeter wire with an eight-millimeter inter wire distance. Familiarize the rat with the test cage for 30 minutes per day for five to seven consecutive days before the first test. In a prone position under isoflurane anesthesia, shave the back hair in the area of interest over approximately 10 vertebral levels using an animal hair trimmer.For repeated measures, shave the back hair every three days without behavioral assessment to ensure that stimuli are always applied directly to the skin. Draw a mark on the skin with a permanent marker to ensure that filaments are always applied to the same area when repeating the test on different days. On the testing day, place the rat in the test cage for 15 to 30 minutes before the test until the rat is calm.Then apply Von Frey filaments perpendicular to the back, always beginning with the two-gram filament and using the up/down method. Apply the filament for two seconds bilaterally to the area of interest 10 millimeters from the spine is processed every 15 to 30 seconds when the rat is awake, standing on its four paws, and not moving. If no response is observed with the application of a filament, apply the next filament with a higher force in the series.If a positive response such as arching the back, licking, muscle twitching, moving away from the filament, or rotation is observed use the next filament with a lower force in the series. Continue the procedure until four readings are obtained after the first behavioral change. In this study, back mechanical sensitivity between CFA and control rats was investigated.At baseline, mechanical sensitivity was similar between groups. Intramuscular injection of CFA in the lumbar muscles caused a marked increase in mechanical sensitivity from seven to 28 days. In contrast, the control rats did not show any significant change.Further, histological examination confirmed the presence of chronic inflammatory changes in the muscles injected with CFA with a clear leukocyte infiltration. Healthy back muscles from a controlled rat after intramuscular injection of saline is shown as a reference. The mechanical hypersensitivity was observed at the hind paw with a standard Von Frey test, in addition to the back muscles.It is very important to make sure that the filament is always applied in the same way perpendicularly to the back, and that the animal is not moving when applying it. The experimenter should also feel confidence in distinguishing behavioral responses for modern movements.

back-mechanical-sensitivity-assessment-rat-for-mechanistic

Research

JoVE Journal

Behavior

Use of the Operant Orofacial Pain Assessment Device (OPAD) to Measure Changes in Nociceptive Behavior

We present an operant system for the detection of pain in awake, conscious rodents. The Orofacial Pain Assessment Device (OPAD) assesses pain behaviors in a more clinically relevant way by not relying on reflex-based measures of nociception. Food fasted, hairless (or shaved) rodents are placed into a Plexiglas chamber which has two Peltier-based thermodes that can be programmed to any temperature between 7 &deg;C and 60 &deg;C. The rodent is trained to make contact with these in order to access a reward bottle. During a session, a number of behavioral pain outcomes are automatically recorded and saved. These measures include the number of reward bottle activations (licks) and facial contact stimuli (face contacts), but custom measures like the lick/face ratio (total number of licks per session/total number of contacts) can also be created. The stimulus temperature can be set to a single temperature or multiple temperatures within a session. The OPAD is a high-throughput, easy to use operant assay which will lead to better translation of pain research in the future as it includes cortical input instead of relying on spinal reflex-based nociceptive assays.

Use of the Operant Orofacial Pain Assessment Device OPAD to Measure Changes in Nociceptive Behavior

We present a user-friendly, high-throughput operant system for the evaluation of pain behaviors in awake, conscious rodents. The Orofacial Pain Assessment Device (OPAD) can assess pain through a reward/conflict paradigm thus providing a more humane way of testing. This protocol will yield more clinically relevant and translational data from rodents.

We present an operant  system for the detection of pain in awake, conscious rodents. The Orofacial  Pain Assessment Device (OPAD) assesses pain behaviors ...

A Protocol of Manual Tests to Measure Sensation and Pain in Humans

Numerous qualitative and quantitative techniques can be used to test sensory nerves and pain in both research and clinical settings. The current study demonstrates a quantitative sensory testing protocol using techniques to measure tactile sensation and pain threshold for pressure and heat using portable and easily accessed equipment. These techniques and equipment are ideal for new laboratories and clinics where cost is a concern or a limiting factor. We demonstrate measurement techniques for the following: cutaneous mechanical sensitivity on the arms and legs (von-Frey filaments), radiant and contact heat sensitivity (with both threshold and qualitative assessments using the Visual Analog Scale (VAS)), and mechanical pressure sensitivity (algometer, with both threshold and the VAS). The techniques and equipment described and demonstrated here can be easily purchased, stored, and transported by most clinics and research laboratories around the world. A limitation of this approach is a lack of automation or computer control. Thus, these processes can be more labor intensive in terms of personnel training and data recording than the more sophisticated equipment. We provide a set of reliability data for the demonstrated techniques. From our description, a new laboratory should be able to set up and run these tests and to develop their own internal reliability data.

The goal of this procedure is to demonstrate a battery of quantitative techniques for sensory and pain measurement in humans. The equipment and techniques described are commonly found in pain clinics or are easy to obtain.

Numerous qualitative and quantitative techniques can be used to test sensory nerves and pain in both research and clinical settings. The current study ...

Novel Object Recognition Test for the Investigation of Learning and Memory in Mice

The object recognition test (ORT) is a commonly used behavioral assay for the investigation of various aspects of learning and memory in mice. The ORT is fairly simple and can be completed over 3 days: habituation day, training day, and testing day. During training, the mouse is allowed to explore 2 identical objects. On test day, one of the training objects is replaced with a novel object. Because mice have an innate preference for novelty, if the mouse recognizes the familiar object, it will spend most of its time at the novel object. Due to this innate preference, there is no need for positive or negative reinforcement or long training schedules. Additionally, the ORT can also be modified for numerous applications. The retention interval can be shortened to examine short-term memory, or lengthened to probe long-term memory. Pharmacological intervention can be used at various times prior to training, after training, or prior to recall to investigate different phases of learning (i.e., acquisition, early or late consolidation, or recall). Overall, the ORT is a relatively low-stress, efficient test for memory in mice, and is appropriate for the detection of neuropsychological changes following pharmacological, biological, or genetic manipulations.

The object recognition test (ORT) is a simple and efficient assay for evaluating learning and memory in mice. The methodology is described below.

The object recognition test (ORT) is a commonly used behavioral assay for the investigation of various aspects of learning and memory in mice. The ORT is ...

Treating Low Back Pain in Failed Back Surgery Patients with Multicolumn-lead Spinal Cord Stimulation

Failed back surgery syndrome (FBSS) refers to persistent, chronic pain following spinal surgery. Spinal cord stimulation with dorsal epidural leads can be used to treat back and leg pain in FBSS patients. This paper presents a detailed protocol for using spinal cord stimulation with surgical leads in FBSS patients. In our department, with the patient under general anesthesia, we place the lead in the epidural space by means of a small laminectomy at the 10th thoracic level. Placement of the lead is followed by a 1 month trial period with an externalized lead. If pain relief is greater than 50% at the end of this 1 month stimulation trial (required by Belgian reimbursement criteria), an internal pulse generator is then placed under the skin and connected to the lead in a second surgical procedure. We have demonstrated that using this technique in rigorously selected FBSS patients can significantly improve back pain, leg pain, patient activity, and quality of life for a sustained period of time.

This paper presents a method that uses spinal cord stimulation with a multicolumn lead to treat neuropathic low back pain in failed back surgery patients.

Failed back surgery syndrome (FBSS) refers to persistent, chronic pain following spinal surgery. Spinal cord stimulation with dorsal epidural leads can be ...

The Unpredictable Chronic Mild Stress Protocol for Inducing Anhedonia in Mice

Depression is a highly prevalent and debilitating condition, only partially addressed by current pharmacotherapies. The lack of response to treatment by many patients prompts the need to develop new therapeutic alternatives and to better understand the etiology of the disorder. Pre-clinical models with translational merits are rudimentary for this task. Here we present a protocol for the unpredictable chronic mild stress (UCMS) method in mice. In this protocol, adolescent mice are chronically exposed to interchanging unpredictable mild stressors. Resembling the pathogenesis of depression in humans, stress exposure during the sensitive period of mice adolescence instigates a depressive-like phenotype evident in adulthood. UCMS can be used for screenings of antidepressants on the variety of depressive-like behaviors and neuromolecular indices. Among the more prominent tests to assess depressive-like behavior in rodents is the sucrose preference test (SPT), which reflects anhedonia (core symptom of depression). The SPT will also be presented in this protocol. The ability of UCMS to induce anhedonia, instigate long-term behavioral deficits and enable reversal of these deficits via chronic (but not acute) treatment with antidepressants strengthens the protocol&#39;s validity compared to other animal protocols for inducing depressive-like behaviors.

Here we present the unpredictable chronic mild stress protocol in mice. This protocol induces a long-term depressive-like phenotype and enables to assess the efficacy of putative antidepressants in reversing the behavioral and neuromolecular depressive-like deficits.

Depression is a highly prevalent and debilitating condition, only partially addressed by current pharmacotherapies. The lack of response to treatment by ...

Multi-Modal Signals for Analyzing Pain Responses to Thermal and Electrical Stimuli

The assessment of pain relies mostly on methods that require a person to communicate. However, for people with cognitive and verbal impairments, existing methods are not sufficient as they lack reliability and validity. To approach this problem, recent research focuses on an objective pain assessment facilitated by parameters of responses derived from physiology, and video and audio signals. To develop reliable automated pain recognition systems, efforts have been made in creating multimodal databases in order to analyze pain and detect valid pain patterns. While the results are promising, they only focus on discriminating pain or pain intensities versus no pain. In order to advance this, research should also consider the quality and duration of pain as they provide additional valuable information for more advanced pain management. To complement existing databases and the analysis of pain regarding quality and length, this paper proposes a psychophysiological experiment to elicit, measure, and collect valid pain reactions. Participants are subjected to painful stimuli that differ in intensity (low, medium, and high), duration (5 s / 1 min), and modality (heat / electric pain) while audio, video (e.g., facial expressions, body gestures, facial skin temperature), and physiological signals (e.g., electrocardiogram [ECG], skin conductance level [SCL], facial electromyography [EMG], and EMG of M. trapezius) are being recorded. The study consists of a calibration phase to determine a subject&#8217;s individual pain range (from low to intolerable pain) and a stimulation phase in which pain stimuli, depending on the calibrated range, are applied. The obtained data may allow refining, improving, and evaluating automated recognition systems in terms of an objective pain assessment. For further development of such systems and to investigate pain reactions in more detail, additional pain modalities such as pressure, chemical, or cold pain should be included in future studies. Recorded data of this study will be released as the &#8220;X-ITE Pain Database&#8221;.

This article focuses on the experimental elicitation of pain through heat (thermal) and electrical stimulation while recording physiological, visual, and paralinguistic responses. It aims at collecting valid multimodal data for analyzing pain based on its intensity, quality, and duration.&#160;

The assessment of pain relies mostly on methods that require a person to communicate. However, for people with cognitive and verbal impairments, existing ...

Chronic Post-Ischemia Pain Model for Complex Regional Pain Syndrome Type-I in Rats

Complex regional pain syndrome type-I (CRPS-I) is a neurological disease that causes severe pain among patients and remains an unresolved medical condition. However, the underlying mechanisms of CRPS-I have yet to be revealed. It is known that ischemia/reperfusion is one of the leading factors that causes CRPS-I. By means of prolonged ischemia and reperfusion of the hind limb, the rat chronic post-ischemia pain (CPIP) model has been established to mimic CRPS-I. The CPIP model has become a well-recognized animal model for studying the mechanisms of CRPS-I. This protocol describes the detailed procedures involved in the establishment of the rat model of CPIP, including anesthesia, followed by ischemia/reperfusion of the hind limb. Characteristics of the rat CPIP model are further evaluated by measuring the mechanical and thermal hypersensitivities of the hind limb as well as the nocifensive responses to acute capsaicin injection. The rat CPIP model exhibits several CRPS-I-like manifestations, including hind limb edema and hyperemia in the early stage after establishment, persistent thermal and mechanical hypersensitivities, and increased nocifensive responses to acute capsaicin injection. These characteristics render it a suitable animal model for further investigation of the mechanisms involved in CRPS-I.

Provided here is a protocol that details steps to establish an animal model of chronic post-ischemia pain (CPIP). This is a well-recognized model mimicking human complex regional pain syndrome type-I. Mechanical and thermal hypersensitivities are further evaluated, as well as capsaicin-induced nocifensive behaviors observed in the CPIP rat model.

Complex regional pain syndrome type-I (CRPS-I) is a neurological disease that causes severe pain among patients and remains an unresolved medical ...

Assessment of Memory Function in Pilocarpine-induced Epileptic Mice

Cognitive impairment is one of the most common comorbidities in temporal lobe epilepsy. To recapitulate epilepsy-associated cognitive decline in an animal model of epilepsy, we generated pilocarpine-treated chronic epileptic mice. We present a protocol for three different behavioral tests using these epileptic mice: novel object location (NL), novel object recognition (NO), and pattern separation (PS) tests to evaluate learning and memory for places, objects, and contexts, respectively. We explain how to set the behavioral apparatus and provide experimental procedures for the NL, NO, and PS tests following an open field test that measures the animals&#8217; basal locomotor activities. We also describe the technical advantages of the NL, NO, and PS tests with respect to other behavioral tests for assessing memory function in epileptic mice. Finally, we discuss possible causes and solutions for epileptic mice failing to make 30 s of good contact with the objects during the familiarization sessions, which is a critical step for successful memory tests. Thus, this protocol provides detailed information about how to assess epilepsy-associated memory impairments using mice. The NL, NO, and PS tests are simple, efficient assays that are appropriate for the evaluation of different kinds of memory in epileptic mice.

This article presents experimental procedures for assessing memory impairments in pilocarpine-induced epileptic mice. This protocol can be used to study the pathophysiologic mechanisms of epilepsy-associated cognitive decline, which is one of the most common comorbidities in epilepsy.

Cognitive impairment is one of the most common comorbidities in temporal lobe epilepsy. To recapitulate epilepsy-associated cognitive decline in an animal ...

Chronic Stress Shifts Effort-Related Choice Behavior in a Y-Maze Barrier Task in Mice

Mood disorders, including major depressive disorder, can be precipitated by chronic stress. The Y-maze barrier task is an effort-related choice test that measures motivation to expend effort and obtain reward. In mice, chronic stress exposure significantly impacts motivation to work for a higher value reward when a lesser value reward is freely available compared to unstressed mice. Here we describe the chronic corticosterone administration paradigm, which produces a shift in effortful responding in the Y-maze barrier task. In the Y-maze task, one arm contains 4 food pellets, while the other arm contains only 2 pellets. After mice learn to select the high reward arm, barriers with progressively increasing height are then introduced into the high reward arm over multiple test sessions. Unfortunately, most chronic stress paradigms (including corticosterone and social defeat) were developed in male mice and are less effective in female mice. Therefore, we also discuss chronic non-discriminatory social defeat stress (CNSDS), a stress paradigm we developed that is effective in both male and female mice. Repeating results with multiple distinct chronic stressors in male and female mice combined with increased usage of translationally relevant behavior tasks will help to advance the understanding of how chronic stress can precipitate mood disorders.

The Y-maze barrier task is a behavior test that examines motivation to expend effort for reward. Here, we discuss testing multiple well-validated chronic stressors including chronic corticosterone and social defeat stress with this behavior, as well as the novel chronic non-discriminatory social defeat stress (CNSDS), which is effective in females.

Mood disorders, including major depressive disorder, can be precipitated by chronic stress. The Y-maze barrier task is an effort-related choice test that ...

An Improved Assay and Tools for Measuring Mechanical Nociception in Drosophila Larvae

Published assays for mechanical nociception in Drosophila have led to variable assessments of behavior. Here, we fabricated, for use with Drosophila larvae, customized metal nickel-titanium alloy (nitinol) filaments. These mechanical probes are similar to the von Frey filaments used in vertebrates to measure mechanical nociception. Here, we demonstrate how to make and calibrate these mechanical probes and how to generate a full behavioral dose-response from subthreshold (innocuous or non-noxious range) to suprathreshold (low to high noxious range) stimuli. To demonstrate the utility of the probes, we investigated tissue damage-induced hypersensitivity in Drosophila larvae. Mechanical allodynia (hypersensitivity to a normally innocuous mechanical stimulus) and hyperalgesia (exaggerated responsiveness to a noxious mechanical stimulus) have not yet been established in Drosophila larvae. Using mechanical probes that are normally innocuous or probes that typically elicit an aversive behavior, we found that Drosophila larvae develop mechanical hypersensitization (both allodynia and hyperalgesia) after tissue damage. Thus, the mechanical probes and assay that we illustrate here will likely be important tools to dissect the fundamental molecular/genetic mechanisms of mechanical hypersensitivity.

An Improved Assay and Tools for Measuring Mechanical Nociception in Drosophila Larvae

The goal of this protocol is to show how to perform an improved assay for mechanical nociception in Drosophila larvae. We use the assay here to demonstrate that mechanical hypersensitivity (allodynia and hyperalgesia) exists in Drosophila larvae.

Published assays for mechanical nociception in Drosophila have led to variable assessments of behavior. Here, we fabricated, for use with Drosophila ...