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

Ces travaux ont été soutenus par une subvention de la Fondation Chiropratique du Québec et du Conseil de recherches en sciences naturelles et en génie du Canada (MP: subvention #06659). La contribution de HK a été soutenue par l’Université du Québec à Trois-Rivières (programme PAIR). La contribution de BP a été soutenue par le Fonds de recherche du Québec en Santé (FRQS) et la Fondation Chiropratique du Québec. La contribution de TP a été appuyée par le Conseil de recherches en sciences naturelles et en génie du Canada. La contribution de NE et EK a été soutenue par la Fondation Chiropratique du Québec. La contribution de MP a été appuyée par le FRQS.

Le protocole expérimental a été approuvé par le comité de protection des animaux de l’Université du Québec à Trois-Rivières et conforme aux lignes directrices du Conseil canadien de protection des animaux et aux lignes directrices du Comité de recherche et d’éthique de l’Association internationale pour l’étude de la douleur (IASP). La présente étude a utilisé six rats Wistar mâles (poids corporel: 320-450 g; âge: 18-22 semaines). Les animaux ont été obtenus d’une source commerciale (voir <str...

<ol>
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Étapes critiques Le test BMS est une méthode simple pour évaluer la sensibilité mécanique dans le dos des rats, soit à un moment donné, soit à plusieurs reprises pendant des jours ou des semaines, lorsque des changements sont attendus (modèles de douleur) ou après une intervention pharmacologique ou non pharmacologique. Les problèmes critiques de la méthode incluent la cage d’essai, dont les dimensions doivent garantir que le rat est confortable mais ne bouge pas trop. Le dos de l’anim...

La lombalgie est la principale cause d’invalidité dans le monde, qui a des conséquences personnelles, économiques et sociales dramatiques 1,2,3,4. Chaque année, environ 37 % de la population est touchée par la lombalgie5. La lombalgie disparaît généralement en quelques semaines, mais récidive chez 24 % à 33 % des individus, devenant chronique dans 5 % à 10 % descas2. Pour comprendre les mécanismes et les impacts de la lombalgie ainsi que les effets de différentes interventions thérapeutiques, plusieurs modèles animaux de lombalgie ont été utilisés, imitant les conditions cliniques ou certains composants de la lombalgie6. Ces modèles de souris et de rats peuvent être classés dans une ou plusieurs des catégories suivantes : (1) lombalgie discogénique7,8,, (2) lombalgie radiculaire 8,9,10,11, (3) arthrose articulaire facettaire 12 et (4) lombalgie musculaire 13,14 . Comme la douleur ne peut pas être mesurée directement chez les espèces non humaines, de nombreux tests ont été développés pour quantifier les comportements douloureux dans ces modèles8. Ces tests évaluent les comportements évoqués par un stimulus nocif (force mécanique 15,16,17, stimulation thermique 18,19,20,21,22,23,24,25) ou produits spontanément26,27,28,29.
Les méthodes utilisant des stimuli mécaniques comprennent le test de Von Frey 15,16 et le test de Randall-Selitto17. Les méthodes utilisant des stimuli thermiques comprennent l’essai de battement de queue18, l’essai de plaque chauffante19, l’essai Hargreaves20 et l’essai de sonde thermique21. Les méthodes utilisant des stimuli froids comprennent le test sur plaque froide22, le test d’évaporation de l’acétone 23 et le test plantaire à froid24. Les méthodes de comportements spontanés comprennent les échelles de grimace26, l’enfouissement 27, l’analyse de la mise en charge et de la marche 28, ainsi qu’une analyse comportementale automatisée29. Malgré ces nombreux tests disponibles, aucun d’entre eux n’est conçu spécifiquement pour les modèles de maux de dos.
L’objectif de cette étude est de mettre au point un test simple et accessible pour évaluer la sensibilité mécanique du dos des rats. La technique est largement basée sur le test de Von Frey appliqué à la surface plantaire de la patte postérieure15,16. Le principe de base du test de Von Frey est d’utiliser une série de monofilaments dans la région d’intérêt, délivrant des forces prédéterminées constantes. Une réponse est considérée comme positive si le rat montre un comportement nocifensif. Le seuil mécanique peut alors être calculé en fonction des filaments qui ont suscité des réponses. Dans la présente étude, une méthode simple et accessible adaptée du test de Von Frey est fournie pour déterminer la sensibilité mécanique dans le dos des 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>
		</tr>
		<tr>
			<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

La lombalgie est la principale cause d’invalidité dans le monde, avec des conséquences personnelles, économiques et sociales dramatiques. Pour développer de nouvelles thérapies, des modèles animaux sont nécessaires pour examiner les mécanismes et l’efficacité des nouvelles thérapies d’un point de vue translationnel. Plusieurs modèles de maux de dos chez les rongeurs sont utilisés dans les enquêtes actuelles. Étonnamment, cependant, aucun test comportemental standardisé n’a été validé pour évaluer la sensibilité mécanique dans les modèles de maux de dos. Ceci est essentiel pour confirmer que les animaux souffrant de maux de dos présumés présentent une hypersensibilité locale aux stimuli nociceptifs et pour surveiller la sensibilité lors d’interventions conçues pour soulager les maux de dos. L’objectif de cette étude est de mettre au point un test simple et accessible pour évaluer la sensibilité mécanique du dos des rats. Une cage d’essai a été fabriquée spécifiquement pour cette méthode; longueur x largeur x hauteur: 50 x 20 x 7 cm, avec un treillis en acier inoxydable sur le dessus. Cette cage d’essai permet l’application de stimuli mécaniques sur le dos. Pour effectuer le test, le dos de l’animal est rasé dans la région d’intérêt et la zone d’essai est marquée pour répéter le test à des jours différents, au besoin. Le seuil mécanique est déterminé avec des filaments de Von Frey appliqués sur les muscles paraspinaux, en utilisant la méthode haut-bas décrite précédemment. Les réponses positives comprennent (1) des contractions musculaires, (2) une cambrure (extension du dos), (3) une rotation du cou (4) un grattage ou un léchage du dos et (5) une fuite. Ce test comportemental (test de sensibilité mécanique du dos (BMS)) est utile pour la recherche mécanistique avec des modèles de maux de dos chez les rongeurs pour le développement d’interventions thérapeutiques pour la prévention et la gestion des maux de dos.

La méthode a été utilisée dans une étude antérieure, dans laquelle des données complètes et des statistiques ont été présentées pour comparer la sensibilité mécanique du dos entre le CFA et les rats témoins30. Des données individuelles représentatives (moyenne des seuils gauche et droit) de six rats inclus dans l’étude précédente sont présentées à la figure 3 et au tableau 1. Au départ, la sensibilité mécanique était simil...

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

Pour développer de nouvelles interventions thérapeutiques pour la prévention et la prise en charge des maux de dos, des modèles animaux sont nécessaires pour examiner les mécanismes et l’efficacité de ces thérapies dans une perspective translationnelle. Le présent protocole décrit le test BMS, une méthode normalisée pour évaluer la sensibilité mécanique dorsale chez le rat.

Évaluation de la sensibilité mécanique du dos chez le rat pour l’étude mécaniste des maux de dos chroniques

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

Ce protocole est utile pour tester la sensibilité mécanique dans le dos. Il est particulièrement intéressant pour les conceptions longitudinales dans des modèles de maux de dos chroniques chez le rat, pour lesquels l’objectif est d’examiner l’efficacité d’une intervention visant à diminuer la sensibilité du dos aux stimuli nocifs. La méthode est simple, accessible et donne des résultats reproductibles chez des expérimentateurs formés.Il est largement basé sur le test de Von Frey, qui est couramment utilisé pour évaluer la sensibilité mécanique à la patte postérieure. Comme pour tout autre test comportemental, les expérimentateurs devraient s’entraîner à standardiser l’application des filaments, et jusqu’à ce que les comportements produits par les stimuli mécaniques soient facilement distingués des autres comportements. Le test est simple, sinon, et il ne devrait pas y avoir de difficulté majeure à l’utiliser.La démonstration de la procédure sera assurée par Nasim Eskandari, un doctorant de mon laboratoire. Pour induire des maux de dos chroniques chez le rat, effectuez une injection intramusculaire de l’adjuvant de Freund complet, ou CFA, dans les muscles du dos. À l’aide d’une aiguille de calibre 27, injecter 150 microlitres d’une émulsion eau-dans-huile prête à l’emploi de CFA dans les muscles paraspinaux unilatéralement ou bilatéralement.Gardez l’aiguille en place pendant au moins trois minutes. Ensuite, fabriquez la cage d’essai pour deux animaux, comprenant une chambre pour chaque animal en montant les deux chambres contiguës sur quatre pattes en plexiglas de 33 centimètres de long. Utilisez du plexiglas transparent pour les parois des chambres et du plexiglas noir pour séparer les chambres afin d’empêcher les animaux de se voir.Ensuite, faites le sol et le plafond de la cage d’essai en utilisant un treillis en acier inoxydable fait d’un fil d’un millimètre avec une distance entre fils de huit millimètres. Familiarisez le rat avec la cage d’essai pendant 30 minutes par jour pendant cinq à sept jours consécutifs avant le premier test. En position couchée sur le ventre sous anesthésie à l’isoflurane, rasez les poils du dos dans la zone d’intérêt sur environ 10 niveaux vertébraux à l’aide d’une tondeuse à poils d’animaux.Pour des mesures répétées, rasez les poils du dos tous les trois jours sans évaluation comportementale pour vous assurer que les stimuli sont toujours appliqués directement sur la peau. Dessinez une marque sur la peau avec un marqueur permanent pour vous assurer que les filaments sont toujours appliqués sur la même zone lorsque vous répétez le test à des jours différents. Le jour du test, placez le rat dans la cage d’essai pendant 15 à 30 minutes avant le test jusqu’à ce que le rat soit calme.Appliquez ensuite les filaments de Von Frey perpendiculairement à l’arrière, en commençant toujours par le filament de deux grammes et en utilisant la méthode haut/bas. Appliquer le filament pendant deux secondes bilatéralement sur la zone d’intérêt à 10 millimètres de la colonne vertébrale est traité toutes les 15 à 30 secondes lorsque le rat est éveillé, debout sur ses quatre pattes et ne bouge pas. Si aucune réponse n’est observée avec l’application d’un filament, appliquer le filament suivant avec une force plus élevée dans la série.Si une réponse positive telle qu’une cambrure du dos, un léchage, des contractions musculaires, un éloignement du filament ou une rotation est observée, utilisez le filament suivant avec une force plus faible dans la série. Continuez la procédure jusqu’à ce que quatre lectures soient obtenues après le premier changement de comportement. Dans cette étude, la sensibilité mécanique dorsale entre le CFA et les rats témoins a été étudiée.Au départ, la sensibilité mécanique était similaire entre les groupes. L’injection intramusculaire de CFA dans les muscles lombaires a provoqué une augmentation marquée de la sensibilité mécanique de sept à 28 jours. En revanche, les rats témoins n’ont montré aucun changement significatif.En outre, l’examen histologique a confirmé la présence de changements inflammatoires chroniques dans les muscles injectés avec CFA avec une infiltration leucocytaire claire. Les muscles sains du dos d’un rat contrôlé après injection intramusculaire de solution saline sont présentés comme référence. L’hypersensibilité mécanique a été observée à la patte postérieure avec un test de Von Frey standard, en plus des muscles du dos.Il est très important de s’assurer que le filament est toujours appliqué de la même manière perpendiculairement au dos et que l’animal ne bouge pas lors de son application. L’expérimentateur doit également se sentir confiant dans la distinction des réponses comportementales pour les mouvements modernes.

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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.

L&#39;utilisation de l&#39;appareil Orofacial d&#39;évaluation de la douleur opérant (OPAD) pour mesurer les changements dans le comportement nociceptif

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

Recherche

Sciences du comportement

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.

Un protocole de tests manuels pour mesurer Sensation et la douleur chez les humains

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.

Test de reconnaissance d’objet nouveau pour la recherche sur l’apprentissage et la mémoire chez les souris

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.

Traiter une lombalgie chez les Patients de chirurgie dos ayant échoué avec Stimulation de la moelle épinière Multicolumn-plomb

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.

Le protocole d’effort doux chronique imprévisible pour induire l’anhédonie chez la souris

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;

Signaux multimodales permettant d’analyser la douleur des réponses à des Stimuli thermiques et électriques

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.

Modèle chronique de douleur de poteau-ischémie pour le syndrome régional complexe de douleur type-I chez les rats

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.

Évaluation de la fonction de mémoire chez les souris épileptiques induites par pilocarpine

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.

Le stress chronique change le comportement de choix lié à l’effort dans une tâche de barrière de Y-Maze chez les souris

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.

Un test amélioré et des outils pour mesurer la nociception mécanique chez les larves de Drosophila

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