Name: the spared nerve injury (sni) model of induced mechanical allodynia in mice
Uploaded: 2011-08-18T13:00:00
Duration: 7 min 44 s
Description: Watch this Scientific Journal Video about The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice at JoVE.com

This work was supported by the Lundbeck Foundation, the Carlsberg Foundation and Dagmar Marshall Foundation.

1. von Frey baseline measurements prior to surgery
For von Frey testing procedure, please refer to section 5.
2. Anesthesia/preparation
<ol>
	<li>Anesthetize the animals (intraperitoneal injection of a mixture of 100mg/kg ketamine and 15 mg/kg Xylazine).</li>
	<li>Place the animal in a quiet place until fully anesthetized (e.g. covered with a paper towel).</li>
	<li>Check reflexes by pinching the tip of the tail and the paws with a pair of tweezers. Be sure that the animals are unresponsive before proceeding.</li>
	<li>Subcutaneously inject (back shoulder area) 0.5ml isotonic saline with antibiotics, e.g. ampicillin (to avoid dehydration and prevent infection, although this is a minor surgical procedure).</li>
	<li>Using an electrical shaver, shave the operative field from slightly below the knee area to the hip area (for right-handed persons the left hind limb is recommended).</li>
	<li>Apply ophthalmic ointment to the eyes with a cotton-wool bud.</li>
	<li>Place the animal on its right side and place the left hindlimb on a small platform to keep it elevated. Secure the leg with adhesive tape.</li>
	<li>Disinfect the operative field with alternating scrubs of ethanol and betadine from surgical site out.</li>
</ol>
3. Surgery
<ol>
	<li>Locate the knee with the thumb of your left hand and use a scalpel to make an app. 1 cm incision in the longitudinal direction proximal to the knee.</li>
	<li>Open the skin by blunt dissection using the tip of a pair of sterile scissors.</li>
	<li>Separate the muscle layer by blunt dissection right next to the clearly visible blood vessel, close to the thigh bone (femur). If done correctly, the muscle layers will easily separate without any bleeding, revealing the sciatic nerve right below the muscles. 
	If bleeding occurs e.g. by damage to a blood vessel close to the knee, use sterile cotton-wool buds or pieces of gaze to absorb the blood. Press until the bleeding stops. </li>
	<li>Place the mouse under a stereo microscope and carefully separate the muscles with a pair of sterile tweezers (nr. 2) to visualize the sciatic nerve. Retractors may also be applied.</li>
	<li>Identify the area where the sural nerve branches from the sciatic nerve. The sural nerve is the smallest of the three branches, branching to the right in the left leg.</li>
	<li>Apply suture (6-0 suture) around the other two branches which are still running in parallel (the tibial and common peroneal nerves), being very careful not to touch the sural branch. This is a critical step as the sural nerve has to be left completely intact.</li>
	<li>Make a tight surgical knot. If the first knot is tight, contractions of the limb will be observed.</li>
	<li>Grab the nerves to be cut below the suture with a pair of tweezers (nr. 5) and cut the nerves above and below tweezers with a small pair of scissors. By first cutting above the pair of tweezers, pulling of the nerves is avoided.</li>
	<li>Cut off suture ends with a pair of micro scissors and gently close the muscle layer. Add a drop of lidocaine to the wound and suture with surgical knots.</li>
</ol>
4. After surgery
<ol>
	<li>Check if eye ointment is still sufficient.</li>
	<li>Place the mouse in a clean cage under a paper towel in a comfortable posture. If the room is cold, place a heat pad under a part of the cage (only under part of 
	the cage as the animal should be able to escape to a colder area if preferred).</li>
	<li>Ensure easily accessible water and chow.</li>
</ol>
5. von Frey testing (baseline, and from the day after surgery)
<ol>
	<li>Place the mice in red colored plastic cylinders placed on a wire mesh table two days and one day prior to surgery. Habituate for 15 min in cylinders prior to 
	testing. The red color of the cylinders helps the mice to quickly relax as they cannot see each other and are in a darker area.</li>
	<li>Verify that the mice are calm and apply von Frey filaments to the lateral part of the paw: Starting with the 0.02 g filament, first apply force to the left paw 
	five times over a total period of 30 seconds (approximately 2 seconds per stimulus) and gauge the mouse's reaction after each application. Repeat with the same 
	filament and the left paw of any other mice, and then start over again with the right paw of the first mouse before moving on to the next filament, e.g.: 
	<ul>
		<li>Mouse 1: left paw 5 times with filament 0.02 g</li>
		<li>Mouse 2: left paw 5 times with filament 0.02 g etc.</li>
		<li>Mouse 1: right paw 5 times with filament 0.02 g</li>
		<li>Mouse 2: right paw 5 times with filament 0.02 g etc.</li>
		<li>Mouse 1: left paw 5 times with filament 0.04 g</li>
		<li>Mouse 2: left paw 5 times with filament 0.04 g etc.</li>
	</ul>
	</li>
	<li>Response in three out of five stimuli is regarded as a positive reaction. Filaments above threshold can be applied to verify the threshold level. 
	Response = sudden paw withdrawal, sudden flinching, sudden paw licking.</li>
</ol>
6. Representative results
<img src="/files/ftp_upload/3092/3092fig1.jpg" alt="Figure 1" /> 
Figure 1. Von Frey testing on C57BL/6 mice age 8-10 weeks old was performed 1 day prior to operation and repeatedly following surgery. 4-8 
animals were included in each group. Von Frey testing on the operated side is represented by ipsilateral and the non-operated control side is 
represented by contralateral. The day after surgery the animals develop significant hypersensitivity on the operated paw while the non-operated is only 
slightly affected relative to sham operated mice. (* &lt;0.05, **&lt;0.01, ***&lt;0.001, ipsilateral relative to contralateral).

<ol>
	<li>Costigan, M., Scholz, J., 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=Neuropathic+pain:+a+maladaptive+response+of+the+nervous+system+to+damage.">Neuropathic pain: a maladaptive response of the nervous system to damage.</a> Annu. Rev. Neurosci. 32, 1-32 (2009).</li><li>Decosterd, I., 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=Spared+nerve+injury:+an+animal+model+of+persistent+peripheral+neuropathic+pain.">Spared nerve injury: an animal model of persistent peripheral neuropathic pain.</a> Pain. 87, 149-158 (2000).</li><li>Bourquin, A. -. F., S&#252;veges, M., Pertin, M., Gilliar, N., Sardy, S., Davidson, A. C., Spahn, D. R., Decosterd, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+and+analysis+of+mechanical+allodynia-like+behavior+induced+by+spared+nerve+injury+(SNI)+in+the+mouse.">Assessment and analysis of mechanical allodynia-like behavior induced by spared nerve injury (SNI) in the mouse.</a> Pain. 122, 14.e1-14.e14 (2006).</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> J. Neurosci. Methods. 53, 55-63 (1994).</li><li>Bennett, G. J., Xie, Y. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+peripheral+mononeuropathy+in+rat+that+produces+disorders+of+pain+sensation+like+those+seen+in+man.">A peripheral mononeuropathy in rat that produces disorders of pain sensation like those seen in man.</a> Pain. 33, 87-107 (1988).</li><li>Seltzer, Z., Dubner, R., Shir, 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+novel+behavioral+model+of+neuropathic+pain+disorders+produced+in+rats+by+partial+sciatic+nerve+injury.">A novel behavioral model of neuropathic pain disorders produced in rats by partial sciatic nerve injury.</a> Pain. 43, 205-218 (1990).</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+cutanous+hyperalgesia.">A new and sensitive method for measuring thermal nociception in cutanous hyperalgesia.</a> Pain. 32, 77-88 (1988).</li><li>Erichsen, H. K., Blackburn-Munro, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+characterization+of+the+spared+nerve+injury+model+of+neuropathic+pain.">Pharmacological characterization of the spared nerve injury model of neuropathic pain.</a> Pain. 98, 151-161 (2002).</li></ol>

No conflicts of interest declared.

Critical steps
Damage to the sural nerve should be avoided in order to study pathological changes in the intact sural nerve following injury to the tibial 
and common peroneal nerves. Collateral damage to the sural nerve may lead to paralysis and can thus be visualized as dragging of the operated hind limb.
Only the lateral side of the paw is innervated by the spared sural nerve and, hence, only this area develops neuropathy. Testing other areas, innervated by the transected nerves, can strongly bias the evaluation of altered mechanical threshold. 
Possible modifications
Other types of ligations may be supplementary in terms of studying pathological pain conditions following peripheral nerve injury, such as chronic constriction injury [5] or partial nerve ligation [6]. Each experimental procedure results in distinct phenotypic changes which should be considered prior to post-surgery testing.
Furthermore, other sensory tests such as thermal hyperalgesia may be applied [7], although this phenotype is less robust following SNI.
Future applications
This technique can be used for testing of drugs altering the development or maintenance of mechanical allodynia [8]. Analysis of the sciatic nerve, the dorsal root ganglia (DRG) and/or the lumbar spinal cord allow research of the molecular mechanisms responsible for the induced phenotype.
Animal experimentation was performed according to good laboratory practice in full compliance with Danish and European regulations. All experiments were approved by the Danish Animal Experiments Inspectorate under the Ministry of Justice (permission number 2006/561-1206).

<table border="1">
	<tbody>
		<tr>
			<td>Anesthesia: Ketamine and Xylazine</td>
			<td>Scalpel</td>
		</tr>
		<tr>
			<td>Ophthalmic ointment</td>
			<td>Pair of tweezers nr. 2</td>
		</tr>
		<tr>
			<td>Electric razor</td>
			<td>Pair of tweezers nr. 5</td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>Pair of scissors for blunt dissection</td>
		</tr>
		<tr>
			<td>70% (v/v) ethanol	</td>
			<td>Micro scissors</td>
		</tr>
		<tr>
			<td>Cotton-wool buds/gaze</td>
			<td>6.0 Prolene non-absorbable suture</td>
		</tr>
		<tr>
			<td>Stereo microscope</td>
			<td>2 x needle holders</td>
		</tr>
		<tr>
			<td>Adhesive tape</td>
			<td>Heat pad</td>
		</tr>
		<tr>
			<td colspan="2">von Frey filaments (0.02 &#x2013; 2.0 g for mice) (Stoelting)</td>
		</tr>
	</tbody>
</table>

the spared nerve injury (sni) model of induced mechanical allodynia in mice

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared nerve injury (SNI) model induces symptoms of neuropathic pain such as mechanical allodynia i.e. pain due to tactile stimuli that do not normally provoke a painful response [1]. 
The SNI mouse model involves ligation of two of the three branches of the sciatic nerve (the tibial nerve and the common peroneal nerve), while the sural nerve is left intact [2]. The lesion results in marked hypersensitivity in the lateral area of the paw, which is innervated by the spared sural nerve. The non-operated side of the mouse can be used as a control. The advantages of the SNI model are the robustness of the response and that it doesn&#x2019;t require expert microsurgical skills.
The threshold for mechanical pain response is determined by testing with von Frey filaments of increasing bending force, which are repetitively pressed against the lateral area of the paw [3], [4]. A positive pain reaction is defined as sudden paw withdrawal, flinching and/or paw licking induced by the filament. A positive response in three out of five repetitive stimuli is defined as the pain threshold. 
As demonstrated in the video protocol, C57BL/6 mice experience profound allodynia as early as the day following surgery and maintain this for several weeks.

Watch this Scientific Journal Video about The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice at JoVE.com

The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice

The Spared Nerve Injury animal model is described here as a mouse model of peripheral neuropathic pain following partial denervation of the sciatic nerve by lesioning the tibial and common peroneal nerve branches, leaving the remaining sural nerve intact. Behavioral modification resulting from mechanical allodynia is quantified by von Frey filaments.

The Spared Nerve Injury (SNI) Model of Induced Mechanical Allodynia in Mice

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared ...

the-spared-nerve-injury-sni-model-induced-mechanical-allodynia

Research

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Medicine

An in vivo Rodent Model of Contraction-induced Injury and Non-invasive Monitoring of Recovery

Muscle strains are one of the most common complaints treated by physicians. A muscle injury is typically diagnosed from the patient history and physical exam alone, however the clinical presentation can vary greatly depending on the extent of injury, the patient's pain tolerance, etc. In patients with muscle injury or muscle disease, assessment of muscle damage is typically limited to clinical signs, such as tenderness, strength, range of motion, and more recently, imaging studies. Biological markers, such as serum creatine kinase levels, are typically elevated with muscle injury, but their levels do not always correlate with the loss of force production. This is even true of histological findings from animals, which provide a "direct measure" of damage, but do not account for all the loss of function. Some have argued that the most comprehensive measure of the overall health of the muscle in contractile force. Because muscle injury is a random event that occurs under a variety of biomechanical conditions, it is difficult to study. Here, we describe an in vivo animal model to measure torque and to produce a reliable muscle injury. We also describe our model for measurement of force from an isolated muscle in situ. Furthermore, we describe our small animal MRI procedure.

An in vivo Rodent Model of Contraction-induced Injury and Non-invasive Monitoring of Recovery

An in vivo animal model of injury is described. The method takes advantage of the subcutaneous position of the fibular nerve. Velocity, timing of muscle activation, and arc of motion are all pre-determined and synchronized using commercial software. Post injury changes are monitored in vivo using MR imaging/spectroscopy.

Muscle strains are one of the most  common complaints treated by physicians. A muscle injury is typically diagnosed from the patient history and  physical ...

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. Although originally developed and used extensively in the rat due to its larger size, the tibial nerve in mice is big enough that it can be easily manipulated with either crush or transection, leaving the peroneal and sural nerve branches of the sciatic nerve intact and thereby preserving their target muscles. Thus, this model offers the advantages of inducing less morbidity and impediment of ambulation than the sciatic nerve transection model and also allows investigators to study the physiologic, cellular and molecular biologic mechanisms regulating the process of muscle atrophy in genetically engineered mice. The tibial nerve supplies the gastrocnemius, soleus and plantaris muscles, so its transection permits the study of denervated skeletal muscle composed of fast twitch type II fibers and/or slow twitch type I fibers. Here we demonstrate the tibial nerve transection model in the C57Black6 mouse. We assess the atrophy of the gastrocnemius muscle, as a representative muscle, at 1, 2, and 4 weeks post-denervation by measuring muscle weights and fiber type specific cross-sectional area on paraffin-embedded histologic sections immunostained for fast twitch myosin.

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of skeletal muscle atrophy. The model surgical protocol is described and demonstrated in C57Black6 mice. &#160;

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. ...

The Sciatic Nerve Cuffing Model of Neuropathic Pain in Mice

Neuropathic pain arises as a consequence of a lesion or a disease affecting the somatosensory system. This syndrome results from maladaptive changes in injured sensory neurons and along the entire nociceptive pathway within the central nervous system. It is usually chronic and challenging to treat. In order to study neuropathic pain and its treatments, different models have been developed in rodents. These models derive from known etiologies, thus reproducing peripheral nerve injuries, central injuries, and metabolic-, infectious- or chemotherapy-related neuropathies. Murine models of peripheral nerve injury often target the sciatic nerve which is easy to access and allows nociceptive tests on the hind paw. These models rely on a compression and/or a section. Here, the detailed surgery procedure for the &#34;cuff model&#34; of neuropathic pain in mice is described. In this model, a cuff of PE-20 polyethylene tubing of standardized length (2 mm) is unilaterally implanted around the main branch of the sciatic nerve. It induces a long-lasting mechanical allodynia, i.e., a nociceptive response to a normally non-nociceptive stimulus that can be evaluated by using von Frey filaments. Besides the detailed surgery and testing procedures, the interest of this model for the study of neuropathic pain mechanism, for the study of neuropathic pain sensory and anxiodepressive aspects, and for the study of neuropathic pain treatments are also discussed.

Neuropathic pain is a consequence of a lesion or disease affecting the somatosensory system. The &#8220;cuff model&#8221; of neuropathic pain in mice consists of the implantation of a polyethylene cuff around the main branch of the sciatic nerve. Mechanical allodynia is tested using von Frey filaments.

Neuropathic pain arises as a consequence of a lesion or a disease affecting the somatosensory system. This syndrome results from maladaptive changes in ...

Facial Nerve Axotomy in Mice: A Model to Study Motoneuron Response to Injury

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and either cut or crush it to induce peripheral nerve injury. Advantages of this surgery are its simplicity, high reproducibility, and the lack of effect on vital functions or mobility from the subsequent facial paralysis, thus resulting in a relatively mild surgical outcome compared to other nerve injury models. A major advantage of using a cranial nerve injury model is that the motoneurons reside in a relatively homogenous population in the facial motor nucleus in the pons, simplifying the study of the motoneuron cell bodies. Because of the symmetrical nature of facial nerve innervation and the lack of crosstalk between the facial motor nuclei, the operation can be performed unilaterally with the unaxotomized side serving as a paired internal control. A variety of analyses can be performed postoperatively to assess the physiologic response, details of which are beyond the scope of this article. For example, recovery of muscle function can serve as a behavioral marker for reinnervation, or the motoneurons can be quantified to measure cell survival. Additionally, the motoneurons can be accurately captured using laser microdissection for molecular analysis. Because the facial nerve axotomy is minimally invasive and well tolerated, it can be utilized on a wide variety of genetically modified mice. Also, this surgery model can be used to analyze the effectiveness of peripheral nerve injury treatments. Facial nerve injury provides a means for investigating not only motoneurons, but also the responses of the central and peripheral glial microenvironment, immune system, and target musculature. The facial nerve injury model is a widely accepted peripheral nerve injury model that serves as a powerful tool for studying nerve injury and regeneration.

We present a surgical protocol detailing how to perform a cut or crush axotomy on the facial nerve in the mouse. The facial nerve axotomy can be employed to study the physiological response to nerve injury and test therapeutic techniques.

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Photothrombosis-induced Focal Ischemia as a Model of Spinal Cord Injury in Mice

Spinal cord injury (SCI) is a devastating clinical condition causing permanent changes in sensorimotor and autonomic functions of the spinal cord (SC) below the site of injury. The secondary ischemia that develops following the initial mechanical insult is a serious complication of the SCI and severely impairs the function and viability of surviving neuronal and non-neuronal cells in the SC. In addition, ischemia is also responsible for the growth of lesion during chronic phase of injury and interferes with the cellular repair and healing processes. Thus there is a need to develop a spinal cord ischemia model for studying the mechanisms of ischemia-induced pathology. Focal ischemia induced by photothrombosis (PT) is a minimally invasive and very well established procedure used to investigate the pathology of ischemia-induced cell death in the brain. Here, we describe the use of PT to induce an ischemic lesion in the spinal cord of mice. Following retro-orbital sinus injection of Rose Bengal, the posterior spinal vein and other capillaries on the dorsal surface of SC were irradiated with a green light resulting in the formation of a thrombus and thus ischemia in the affected region. Results from histology and immunochemistry studies show that PT-induced ischemia caused spinal cord infarction, loss of neurons and reactive gliosis. Using this technique a highly reproducible and relatively easy model of SCI in mice can be achieved that would serve the purpose of scientific investigations into the mechanisms of ischemia induced cell death as well as the efficacy of neuroprotective drugs. This model will also allow exploration of the pathological changes that occur following SCI in live mice like axonal degeneration and regeneration, neuronal and astrocytic Ca2+ signaling using two-photon microscopy.

Photothrombosis is a minimally invasive and highly reproducible procedure to induce focal ischemia in the spinal cord and serves as a model of spinal cord injury in mice.

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A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

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Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

A Tissue Displacement-based Contusive Spinal Cord Injury Model in Mice

Producing a consistent and reproducible contusive spinal cord injury (SCI) is critical to minimizing behavioral and histological variabilities between experimental animals. Several contusive SCI models have been developed to produce injuries using different mechanisms. The severity of the SCI is based on the height that a given weight is dropped, the injury force, or the spinal cord displacement. In the current study, we introduce a novel mouse contusive SCI device, the Louisville Injury System Apparatus (LISA) impactor, which can create a displacement-based SCI with high injury velocity and accuracy. This system utilizes laser distance sensors combined with advanced software to produce graded and highly-reproducible injuries. We performed a contusive SCI at the 10th thoracic vertebral (T10) level in mice to demonstrate the step-by-step procedure. The model can also be applied to the cervical and lumbar spinal levels.

We introduce a tissue displacement-based contusive spinal cord injury model that can produce a consistent contusive spinal cord injury in adult mice.

Producing a consistent and reproducible contusive spinal cord injury (SCI) is critical to minimizing behavioral and histological variabilities between ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...