All rats were used according to protocols approved by the Animal Experimental Committee of Beijing Friendship Hospital, Capital Medical University.
1. Surgical preparation, anesthetization, and surgical techniques
NOTE: A total of 40 female Wistar rats, weighing 200&#8211;220 g, were commercially obtained for the present study. Of the 40 rats, 10 were randomly selected as the control group, and the rest were treated as the test group. All animals were housed in a sterile environment in the animal facilities of Beijing Friendship Hospital, Capital Medical University.
<ol>
	<li>Perform general anesthesia by administering sodium pentobarbital intraperitoneally (40 mg/kg). Alternatively, induce&#160;anesthesia using 3%-4% isoflurane and maintain it at 1%-3% (inhaled). Apply ophthalmic ointment on the&#160;eyes to prevent dryness. Then, place the rat on the surgical platform&#160;and provide thermal support.&#160; 
	NOTE:&#160;Administer analgesics such as buprenorphine, 0.05 mg/kg, SC, 0.1-0.2 mL at the beginning of the procedure.</li>
	<li>Check for the depth of anesthesia by the lack of response to the toe pinch. Shave the fur from the whole back area with a razor.</li>
	<li>Sterilize the surgical site with at least 3 cycles of a two-stage scrub such as Chlorhexidine or Povidone iodine followed by Isopropyl alcohol. Secure the limbs with surgical tape and make a median incision of about 3 cm on the back with surgical scissors.</li>
	<li>Deepen the incision through the subcutaneous tissues using surgical scissors&#160;and cut off the muscles attached to the spine.</li>
	<li>Visually identify and expose the 13th rib (the intervertebral space connected to that rib is interval T13&#8210;L1). Mark the 13th rib using a suture.</li>
	<li>After identification, carefully resect the muscles attached to the spine and expose the vertebral column. Resect the supraspinous ligament and interspinous ligament for an accurate identification of the vertebral column. Expose the level of L4&#8210;L5 with surgical scissors&#160;and forceps. 
	NOTE: The supraspinous ligament can be identified easily because of the presence of thin subcutaneous tissue. After the resection of supraspinous ligament, the ligament between spinous process is interspinous ligament.</li>
	<li>Carefully dissect away the L4&#8210;L5 vertebral spinous process and parts of the transverse process using Kelly forceps to expose the spinal cord (Figure 1).</li>
	<li>Completely expose the conus medullaris at the L4&#8210;L5 level and transect the conus medullaris totally with iridectomy scissors. Insert some tissue packing to block the recovery of the spinal cord.</li>
	<li>Close the overlying muscle and skin on the outer skin layer using 4-0 non-absorbable suture.</li>
	<li>For the control group, perform steps 1.1&#8210;1.7, and leave the conus medullaris intact. Close the incision according to step 1.9.</li>
</ol>
2. Animal recovery
<ol>
	<li>Keep the rats in a temperature-controlled incubator (37&#160;&#176;C) during the first hour post-operation and monitor them until they are&#160;sternal or actively moving. 
	NOTE: It takes about half an hour for total recovery.</li>
	<li>Transfer the animal to a clean cage with sufficient food and water. Keep the rats in separate cages. 
	NOTE: The transection&#39;s success is indicated when the rats in the test group move only with the help of forelegs, whereas the rats in the control group could walk normally.</li>
</ol>
3. Post-operation management
<ol>
	<li>Inject Penicillin G, an antibiotic (50,000 U/mL per animal) intraperitoneally. Administer analgesics such as buprenorphine, 0.05 mg/kg, SC, 0.1-0.2 mL&#160;every 6-12 hr for 48 hr post-operation.</li>
	<li>Compress the urinary bladder at the hypogastrium to help with the voiding. Perform this twice daily at the same time (8 am and 8 pm) for six weeks. 
	NOTE: The loss of normal constriction of detrusor is the symbol of DU.</li>
	<li>House all rats in metabolic cages, each containing a urine collection funnel placed over a previously weighed absorbent paper to monitor the micturition and incontinence.</li>
	<li>Collect and note the weight change of absorbent paper, which indicates the voided volume (VV), and the residual urine volume separately.</li>
</ol>
4. Urodynamic testing
<ol>
	<li>At six-weeks post-operation, perform a cystometrogram, using urodynamic measurement equipment as follows.
	<ol>
		<li>Anesthetize rats by injecting 10% chloral hydrate into the peritoneal cavity (3 mL/kg).</li>
		<li>Compress the bladder for voiding, then fix the rat to the surgical platform using a tape.</li>
		<li>Insert the epidural catheter (3F) into the bladder and connect the urodynamic measurement equipment, epidural catheter, and infusion pump by the three-limb tube.</li>
		<li>Pump physiological saline at a speed of 0.2 mL/min for urodynamic measurement (see Table of Materials). Record the MCC and DOP, and compliance of the bladder (calculated by dividing &#948; bladder volume with &#948; pressure of the detrusor).</li>
	</ol>
	</li>
</ol>
5. Statistical analysis
<ol>
	<li>Perform statistical analysis using commercially available software.</li>
	<li>Use Kolmogorov-Smirnov test to test the normality of data.</li>
	<li>Express the normally distributed variables as mean values with standard deviations. Use the two-tailed paired Student&#8217;s t-tests to compare the parameters of cystometrogram in both groups. 
	NOTE: p &#60; 0.05 indicates that the difference had statistical significance.</li>
</ol>

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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contemporary+concepts+in+the+aetiopathogenesis+of+detrusor+underactivity.">Contemporary concepts in the aetiopathogenesis of detrusor underactivity.</a> Nature Reviews. Urology. 11 (11), 639-648 (2014).</li><li>Panicker, J. N., Nagaraja, D., Kovoor, J. M. E., Nair, K. P. S., Subbakrishna, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lower+urinary+tract+dysfunction+in+acute+disseminated+encephalomyelitis.">Lower urinary tract dysfunction in acute disseminated encephalomyelitis.</a> Multiple Sclerosis. 15 (9), 1118-1122 (2009).</li><li>Lee, W. C., Wu, H. P., Tai, T. Y., Yu, H. J., Chiang, P. 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B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Underactive+bladder;+Review+of+progress+and+impact+from+the+International+CURE-UAB+Initiative.">Underactive bladder; Review of progress and impact from the International CURE-UAB Initiative.</a> International Neurourology Journal. 24 (1), 3-11 (2020).</li><li>Pfisterer, M. H. D., Griffiths, D. J., Schaefer, W., Resnick, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+age+on+lower+urinary+tract+function:+a+study+in+women.">The effect of age on lower urinary tract function: a study in women.</a> Journal of the American Geriatrics Society. 54 (3), 405-412 (2006).</li><li>Duchen, L. W., Anjorin, A., Watkins, P. J., Mackay, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathology+of+autonomic+neuropathy+in+diabetes+mellitus.">Pathology of autonomic neuropathy in diabetes mellitus.</a> Annals of Internal Medicine. 92 (2), 301-303 (1980).</li><li>Schneider, T., Hein, P., Bai, J., Michel, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+muscarinic+receptors+or+rho-kinase+in+hypertension+associated+rat+bladder+dysfunction.">A role for muscarinic receptors or rho-kinase in hypertension associated rat bladder dysfunction.</a> The Journal of Urologoy. 173 (6), 2178-2181 (2005).</li><li>Drake, M. J., Harvey, I. J., Gillespie, J. I., Van Duyl, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localized+contractions+in+the+normal+human+bladder+and+in+urinary+urgency.">Localized contractions in the normal human bladder and in urinary urgency.</a> BJU International. 95 (7), 1002-1005 (2005).</li><li>Suskind, A. M., Smith, P. P. <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+look+at+detrusor+underactivity:+impaired+contractility+versus+afferent+dysfunction.">A new look at detrusor underactivity: impaired contractility versus afferent dysfunction.</a> Current Urology Reports. 10 (5), 347-351 (2009).</li><li>Osman, N. 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The authors have nothing to disclose.

DU is a common cause of lower urinary tract symptoms in both men and women. It is a complex constellation of symptoms with few treatment options that can significantly diminish the quality-of-life (Qol) of those affected18. Although it is believed that DU is multifactorial, the understanding of its pathogenesis remains rudimentary. Studies have shown that the pathogenesis of DU might be related to myogenic and neurogenic factors.
In the myogenic hypotheses, it was obser...

Detrusor underactivity (DU) is a typical lower urinary tract dysfunction that has remained under studied. Even though DU has been defined by the International Continence Society (ICS)1, numerous different terminologies are used to refer to this disease, e.g., &#8220;detrusor failure,&#8221; &#8220;acontractile bladder,&#8221; &#8220;detrusor areflexia&#8221;2. DU, as defined by the International Continence Society (ICS) in 2002, is a contraction of reduced strength and duration, which results in prolonged increase in time for bladder emptying, thereby resulting in failure to achieve complete bladder emptying within a normal period.
DU may affect 48% of men and 12% of women (aged &#62;70 years)3 with lower urinary tract symptoms. It seems to be multifactorial, and no effective treatment exists. It is reported that DU is ubiquitous in patients with neurogenic bladder dysfunction, such as multiple sclerosis4, diabetes mellitus5, Parkinson&#8217;s disease6, or cerebral stroke7. DU can also be caused by iatrogenic nerve damage, such as laparoscopic hysterectomy, prostatectomy, or other surgical interventions in the small pelvis8. The pathophysiology changes and available treatments of DU are still confusing because of the lack of an appropriate animal model for study.
The micturition reflex is controlled by spino-bulbospinal pathways that combines the pontine micturition center, sacral parasympathetic nucleus, and more senior cortex centers9. Activation and maintenance of the micturition reflex mainly depend on the regular transport of sensory signals from the bladder to more senior cortex centers. It may be postulated that sensory dysfunction contributes to DU.
Most experimental animal studies related to lower urinary tract dysfunctions have focused on overactive bladder (OAB) models10. These models provide a reasonable understanding of OAB pathophysiology and prognosis. However, only a few DU models have been reported, e.g., supraspinal injury (local lesions, decerebration, and middle cerebral artery occlusion), spinal cord transection or contusion injury, systemic (e.g., cyclophosphamide) or intravesical administration of irritant or in&#64258;ammatory agents (e.g., acid, acrolein, and lipopolysaccharide)11,12,13,14. Among these methods, only the spinal cord transection or contusion injury method can be used in establishing an animal model of DU13. Attempts involving the injury of the pontine micturition center and higher cortex centers were abandoned because of the severe trauma. So, increased attention is being paid to find an accurate location in the micturition reflex center to induce the DU with minimum side effects.
As mentioned previously, one of the mechanisms of inducing DU is to injure the spinal cord to damage the signaling pathway of the micturition reflex. Allen&#8217;s weight-drop method was developed to establish laboratory animals with injured spinal cords15. However, there are no further experimental data available on this method. Moreover, since parts of the animals recovered spinal function after stroke without DU, it cannot be considered as a perfect method for generating a DU animal model16.
In 1987, Bregman excogitated a process of transecting the spinal cord for generating the DU animal model and acquired experimental data17. Nevertheless, this method was not applied to establish the DU animal model. At that time, researchers were still confused about the pathogenesis of DU. As locations in the spinal cord associated with the induction of OAB or DU are adjacent to each other, they were unable to find the accurate site of damage to the spinal cord to induce DU17. OAB and DU were introduced either together or separately by this method. So, although this method introduced DU, it was imprecise and could not be used for the understanding of DU&#8217;s occurrence and processing.
As stated above, the lack of a suitable animal model of DU is one of the main obstacles for the study of DU. Researchers are continuously looking for an accurate and manageable model that can simulate the pathology of DU. Even the treatment options for DU have not significantly improved during the last 20 years. Collectively, there is a great need to describe a standard protocol for establishing an animal model of DU.
So, in this paper, we describe a method to successfully establish a rat model of DU by conus medullaris transection. Transection was performed at the L4&#8210;L5 level to separate the conus medullaris. The maximum cystometric capacity (MCC), detrusor opening pressure (DOP), and compliance of the bladder were recorded and analyzed to validate the protocol. The protocol stated below combines both feasibility and reliability in a standardized manner to establish the DU animal model, simulating the occurrence and processing of DU. The protocol can be used as a technique for further study of DU.

<table>
	<tbody>
		<tr>
			<td>0.9% saline</td>
			<td>Wuhan Prosai Company</td>
			<td>EY-C1178</td>
			<td>pump for urodynamic measurement</td>
		</tr>
		<tr>
			<td>10% chloral hydrate</td>
			<td>Shandong Yulong Co., Ltd</td>
			<td>H37022673</td>
			<td>3mL/kg&#65292;administered intraperitoneally</td>
		</tr>
		<tr>
			<td>Buprenorphine Hydrochloride Injection</td>
			<td>Tianjin Pharmaceutical Research Institute Pharmaceutical Co. LTD</td>
			<td>H12020275</td>
			<td>0.05mg/kg subcutaneously 24h and 48h postoperation</td>
		</tr>
		<tr>
			<td>Epidural Catheter</td>
			<td>Shandong Xinghua Co, Ltd</td>
			<td>VABR3L</td>
			<td>for urodynamic measurement</td>
		</tr>
		<tr>
			<td>Penicillin G</td>
			<td>Alta Technology Co., Ltd</td>
			<td>1ST5637</td>
			<td>50,000 unit/ml per animal</td>
		</tr>
		<tr>
			<td>pentobarbital</td>
			<td>Beijing solabo Technology Co., Ltd</td>
			<td>NK-WF0001</td>
			<td>40 mg/kg, administered intraperitoneally</td>
		</tr>
		<tr>
			<td>Suture line(4-0)</td>
			<td>ETHICON</td>
			<td>VCP422H</td>
			<td>suture the injury</td>
		</tr>
		<tr>
			<td>Three-limb tube</td>
			<td>Shandong Xinghua Co, Ltd</td>
			<td>VAB3T</td>
			<td>for urodynamic measurement</td>
		</tr>
		<tr>
			<td>Trace infusion pump</td>
			<td>Zhejiang Smith Medical Instrument Co., Ltd</td>
			<td>20162540335</td>
			<td>Pump the saline at a speed of 0.2ml/min for urodynamic measurement</td>
		</tr>
		<tr>
			<td>Urodynamic measurement equipment</td>
			<td>Medical Measurement SystemsB.V.</td>
			<td>08-0467</td>
			<td>urodynamic measurement equipment can not only help the diagnosis of dysuria, but also provide objective materials for treatment and therapeutic effect. It is the most commonly used examination method in clinical diagnosis and treatment of lower urinary tract functional diseases</td>
		</tr>
		<tr>
			<td>Wistar Rats</td>
			<td>HFK Biotechnology Co.Ltd,Beijing ,China</td>
			<td>SCXK2012-0023</td>
			<td>200-220g</td>
		</tr>
	</tbody>
</table>

detrusor underactivity model in rats by conus medullaris transection

The goal of the presented protocol was to establish a detrusor underactivity (DU) model in the rat through conus medullaris transection. Laminectomy was performed in a total of 40 female Wistar rats (control group: 10 rats; test group: 30 rats) weighing 200&#8211;220 g, and the conus medullaris was transected at the L4&#8210;L5 level in the test group. All the rats were housed and fed under the same environmental conditions for six weeks. In the test group, urine voiding was performed twice daily for six weeks, and mean residual urine volume was recorded. A cystometrogram was performed in both groups. Maximum cystometric capacity (MCC), detrusor opening pressure (DOP), and compliance of the bladder were recorded and calculated. The test group showed significant urinary retention after the surgery, both during and after the spinal shock. However, no abnormality was observed in the control group. When compared to the control group, the MCC and compliance of bladder in the test group was significantly higher than that of the test group (3.24 &#177; 2.261 mL versus 1.04 &#177; 0.571 mL; 0.43 &#177; 0.578 mL/cmH2O versus 0.032 &#177; 0.016 mL/cmH2O), whereas DOP in the test group was lower than control (20.28 &#177; 14.022 cmH2O versus 35 &#177; 13.258 cmH2O). This method of establishing an animal model of DU by the conus medullaris transection offers an excellent opportunity to understand DU&#8217;s pathophysiology in a better manner.

The entire procedure of the conus medullaris transection can be completed within 45 min by experienced surgeons. Our laboratory has performed over 100 cases of conus medullaris transection surgeries. The success rate is over 95%, as defined by the rats&#8217; survival and successful induction of DU. The urodynamic test confirmed the induction of DU.
Based on our experience, the induction of DU can be preliminarily evaluated by the residual urine volume. The retention of urine was observed imme...

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Detrusor Underactivity Model in Rats by Conus Medullaris Transection

We present a method for establishing a detrusor underactivity model by conus medullaris transection in rats. Detrusor underactivity was successfully stimulated in these animals. The model can be used for studying urinary tract function.

The goal of the presented protocol was to establish a detrusor underactivity (DU) model in the rat through conus medullaris transection. Laminectomy was ...

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2.0K Views.  Capital Medical University. We present a method for establishing a detrusor underactivity model by conus medullaris transection in rats. Detrusor underactivity was successfully stimulated in these animals. The model can be used for studying urinary tract function.

Video: Detrusor Underactivity Model in Rats by Conus Medullaris Transection

Optic Nerve Transection: A Model of Adult Neuron Apoptosis in the Central Nervous System

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. 
The optic nerve can be accessed within the orbit of the eye and completely transected (axotomized), cutting the axons of the entire RGC population. Optic nerve 
transection is a reproducible model of apoptotic neuronal cell death in the adult CNS 1-4. This model is particularly attractive because the vitreous
 chamber of the eye acts as a capsule for drug delivery to the retina, permitting experimental manipulations via intraocular injections. The diffusion of chemicals 
through the vitreous fluid ensures that they act upon the entire RGC population. Moreover, RGCs can be selectively transfected by applying short interfering RNAs 
(siRNAs), plasmids, or viral vectors to the cut end of the optic nerve 5-7 or injecting vectors into their target, the superior colliculus 8. 
This allows researchers to study apoptotic mechanisms in the desired neuronal population without confounding effects on other bystander neurons or surrounding glia. 
An additional benefit is the ease and accuracy with which cell survival can be quantified after injury. The retina is a flat, layered tissue and RGCs are localized in 
the innermost layer, the ganglion cell layer. The survival of RGCs can be tracked over time by applying a fluorescent tracer (3% Fluorogold) to the cut end of the 
optic nerve at the time of axotomy, or by injecting the tracer into the superior colliculus (RGC target) one week prior to axotomy. The tracer is retrogradely transported, labeling 
the entire RGC population. Because the ganglion cell layer is a monolayer (one cell thick), RGC densities can be quantified in flat-mounted tissue, without the need 
for stereology. Optic nerve transection leads to the apoptotic death of 90% of injured RGCs within 14 days postaxotomy 9-11. RGC apoptosis has a 
characteristic time-course whereby cell death is delayed 3-4 days postaxotomy, after which the cells rapidly degenerate. This provides a time window for 
experimental manipulations directed against pathways involved in apoptosis.

Optic Nerve transection is a widely used model of adult CNS injury. Ninety percent of retinal ganglion cells (RGCs) whose axons are completely transected (axotomy) die within 14 days after axotomy. This model is easily amenable to experimental manipulations and highly reproducible.

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. 
The optic nerve can be ...

Methods for Experimental Manipulations after Optic Nerve Transection in the Mammalian CNS

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. The optic nerve can be accessed within the orbit of the eye and completely transected (axotomized), cutting the axons of the entire RGC population. Optic nerve transection is a reproducible model of apoptotic neuronal cell death in the adult CNS 1-4. This model is particularly attractive because the vitreous chamber of the eye acts as a capsule for drug delivery to the retina, permitting experimental manipulations via intraocular injections. The diffusion of chemicals through the vitreous fluid ensures that they act upon the entire RGC population. Viral vectors, plasmids or short interfering RNAs (siRNAs) can also be delivered to the vitreous chamber in order to infect or transfect retinal cells 5-12. The high tropism of Adeno-Associated Virus (AAV) vectors is beneficial to target RGCs, with an infection rate approaching 90% of cells near the injection site 6, 7, 13-15. Moreover, RGCs can be selectively transfected by applying siRNAs, plasmids, or viral vectors to the cut end of the optic nerve 16-19 or injecting vectors into their target the superior colliculus 10. This allows researchers to study apoptotic mechanisms in the injured neuronal population without confounding effects on other bystander neurons or surrounding glia. RGC apoptosis has a characteristic time-course whereby cell death is delayed 3-4 days postaxotomy, after which the cells rapidly degenerate. This provides a window for experimental manipulations directed against pathways involved in apoptosis. Manipulations that directly target RGCs from the transected optic nerve stump are performed at the time of axotomy, immediately after cutting the nerve. In contrast, when substances are delivered via an intraocular route, they can be injected prior to surgery or within the first 3 days after surgery, preceding the initiation of apoptosis in axotomized RGCs. In the present article, we demonstrate several methods for experimental manipulations after optic nerve transection.

Optic Nerve transection is a widely used model of adult CNS injury. This model is ideal for performing a number of experimental manipulations that target the retina globally or directly target the injured neuronal population of retinal ganglion cells.

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. The optic nerve can be ...

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural connectivity form during development. In mice, retinofugal projections are arranged in a topographic manner and form eye-specific layers in the Lateral Geniculate Nucleus (dLGN) of the thalamus and the Superior Colliculus (SC). The development of these precise patterns of retinofugal projections has typically been studied by labeling populations of RGCs with fluorescent dyes and tracers, such as horseradish peroxidase1-4. However, these methods are too coarse to provide insight into developmental changes in individual RGC axonal arbor morphology that are the basis of retinotopic map formation. They also do not allow for the genetic manipulation of RGCs.
Recently, electroporation has become an effective method for providing precise spatial and temporal control for delivery of charged molecules into the retina5-11. Current retinal electroporation protocols do not allow for genetic manipulation and tracing of retinofugal projections of a single or small cluster of RGCs in postnatal mice. It has been argued that postnatal in vivo electroporation is not a viable method for transfecting RGCs since the labeling efficiency is extremely low and hence requires targeting at embryonic ages when RGC progenitors are undergoing differentiation and proliferation6. 
In this video we describe an in vivo electroporation protocol for targeted delivery of genes, shRNA, and fluorescent dextrans to murine RGCs postnatally. This technique provides a cost effective, fast and relatively easy platform for efficient screening of candidate genes involved in several aspects of neural development including axon retraction, branching, lamination, regeneration and synapse formation at various stages of circuit development. In summary we describe here a valuable tool which will provide further insights into the molecular mechanisms underlying sensory map development.

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

We demonstrate an in vivo electroporation protocol for transfecting single or small clusters of retinal ganglion cells (RGCs) and other retinal cell types in postnatal mice over a wide range of ages. The ability to label and genetically manipulate postnatal RGCs in vivo is a powerful tool for developmental studies.

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural ...

A General Method for Evaluating Incubation of Sucrose Craving in Rats

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and relapse to food taking 1. Food craving conceptualized in this way is akin to drug craving in response to drug-paired cues. A rich literature has been developed around understanding the behavioral and neurobiological determinants of drug craving; we and others have been focusing recently on translating techniques from basic addiction research to better understand addiction-like behaviors related to food 2-4.
As done in previous studies of drug craving, we examine sucrose craving behavior by utilizing a rat model of relapse. In this model, rats self-administer either drug or food in sessions over several days. In a session, lever responding delivers the reward along with a tone+light stimulus. Craving behavior is then operationally defined as responding in a subsequent session where the reward is not available. Rats will reliably respond for the tone+light stimulus, likely due to its acquired conditioned reinforcing properties 5. This behavior is sometimes referred to as sucrose seeking or cue reactivity. In the present discussion we will use the term "sucrose craving" to subsume both of these constructs.
In the past decade, we have focused on how the length of time following reward self-administration influences reward craving. Interestingly, rats increase responding for the reward-paired cue over the course of several weeks of a period of forced-abstinence. This "incubation of craving" is observed in rats that have self-administered either food or drugs of abuse 4,6. This time-dependent increase in craving we have identified in the animal model may have great potential relevance to human drug and food addiction behaviors.
Here we present a protocol for assessing incubation of sucrose craving in rats. Variants of the procedure will be indicated where craving is assessed as responding for a discrete sucrose-paired cue following extinction of lever pressing within the sucrose self-administration context (Extinction without cues) or as responding for sucrose-paired cues in a general extinction context (Extinction with cues).

Responding for food or drug-paired cues increases over the course of a period of abstinence and this may relate to an increased susceptibility to relapse behaviors. Here we detail a procedure for evaluating this "incubation of craving" in rats that have self-administered sucrose.

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and ...

Generation of Topically Transgenic Rats by In utero Electroporation and In vivo Bioluminescence Screening

In utero electroporation (IUE) is a technique which allows genetic modification of cells in the brain for investigating neuronal development. So far, the use of IUE for investigating behavior or neuropathology in the adult brain has been limited by insufficient methods for monitoring of IUE transfection success by non-invasive techniques in postnatal animals. 
 For the present study, E16 rats were used for IUE. After intraventricular injection of the nucleic acids into the embryos, positioning of the tweezer electrodes was critical for targeting either the developing cortex or the hippocampus. 
 Ventricular co-injection and electroporation of a luciferase gene allowed monitoring of the transfected cells postnatally after intraperitoneal luciferin injection in the anesthetized live P7 pup by in vivo bioluminescence, using an IVIS Spectrum device with 3D quantification software. 
 Area definition by bioluminescence could clearly differentiate between cortical and hippocampal electroporations and detect a signal longitudinally over time up to 5 weeks after birth. This imaging technique allowed us to select pups with a sufficient number of transfected cells assumed necessary for triggering biological effects and, subsequently, to perform behavioral investigations at 3 month of age. As an example, this study demonstrates that IUE with the human full length DISC1 gene into the rat cortex led to amphetamine hypersensitivity. Co-transfected GFP could be detected in neurons by post mortem fluorescence microscopy in cryosections indicating gene expression present at &ge;6 months after birth.
 We conclude that postnatal bioluminescence imaging allows evaluating the success of transient transfections with IUE in rats. Investigations on the influence of topical gene manipulations during neurodevelopment on the adult brain and its connectivity are greatly facilitated. For many scientific questions, this technique can supplement or even replace the use of transgenic rats and provide a novel technology for behavioral neuroscience.

Generation of Topically Transgenic Rats by In utero Electroporation and In vivo Bioluminescence Screening

Genes can be manipulated during development of the cortex or the hippocampus of the rat via in utero electroporation (IUE) at E16, to enable fast and targeted modifications in neuronal connectivity for later studies of behavior or neuropathology in adult animals. Postnatal in vivo imaging for control of IUE success is performed by bioluminescence of activating co-transfected luciferase.

 In utero electroporation (IUE) is a technique which allows genetic modification of cells in the brain for investigating neuronal development. So far, the ...

Motor Nerve Transection and Time-lapse Imaging of Glial Cell Behaviors in Live Zebrafish

The nervous system is often described as a hard-wired component of the body even though it is a considerably fluid organ system that reacts to external stimuli in a consistent, stereotyped manner, while maintaining incredible flexibility and plasticity. Unlike the central nervous system (CNS), the peripheral nervous system (PNS) is capable of significant repair, but we have only just begun to understand the cellular and molecular mechanisms that govern this phenomenon. Using zebrafish as a model system, we have the unprecedented opportunity to couple regenerative studies with in vivo imaging and genetic manipulation. Peripheral nerves are composed of axons surrounded by layers of glia and connective tissue. Axons are ensheathed by myelinating or non-myelinating Schwann cells, which are in turn wrapped into a fascicle by a cellular sheath called the perineurium. Following an injury, adult peripheral nerves have the remarkable capacity to remove damaged axonal debris and re-innervate targets. To investigate the roles of all peripheral glia in PNS regeneration, we describe here an axon transection assay that uses a commercially available nitrogen-pumped dye laser to axotomize motor nerves in live transgenic zebrafish. We further describe the methods to couple these experiments to time-lapse imaging of injured and control nerves. This experimental paradigm can be used to not only assess the role that glia play in nerve regeneration, but can also be the platform for elucidating the molecular mechanisms that govern nervous system repair.

Although the peripheral nervous system (PNS) is capable of significant repair after injury, little is known about the cellular and molecular mechanisms that govern this phenomenon. Using live, transgenic zebrafish and a reproducible nerve transection assay, we can study dynamic glial cell behaviors during nerve degeneration and regeneration.

The  nervous system is often described as a hard-wired component of the body even  though it is a considerably fluid organ system that reacts to external ...

Spinal Cord Transection in the Larval Zebrafish

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability to reinitiate spinal neurogenesis. However, some anamniotes including the zebrafish Danio rerio exhibit both sensory and functional recovery even after complete transection of the spinal cord. The adult zebrafish is an established model organism for studying regeneration following spinal cord injury, with sensory and motor recovery by 6&#160;weeks post-injury. To take advantage of in vivo analysis of the regenerative process available in the transparent larval zebrafish as well as genetic tools not accessible in the adult, we use the larval zebrafish to study regeneration after spinal cord transection. Here we demonstrate a method for reproducibly and verifiably transecting the larval spinal cord. After transection, our data shows sensory recovery beginning at 2&#160;days post-injury (dpi), with the C-bend movement detectable by 3 dpi and resumption of free swimming by 5 dpi. Thus we propose the larval zebrafish as a companion tool to the adult zebrafish for the study of recovery after spinal cord injury.

After spinal transection, adult zebrafish have functional recovery by six weeks post-injury. To take advantage of larval transparency and faster recovery, we present a method for transecting the larval spinal cord. After transection, we observe sensory recovery beginning at 2&#160;days post-injury, and C-bend movement by 3 days post-injury.

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability ...

A Lateralized Odor Learning Model in Neonatal Rats for Dissecting Neural Circuitry Underpinning Memory Formation

Rat pups during a critical postnatal period (&#8804; 10 days) readily form a preference for an odor that is associated with stimuli mimicking maternal care. Such a preference memory can last from hours, to days, even life-long, depending on training parameters. Early odor preference learning provides us with a model in which the critical changes for a natural form of learning occur in the olfactory circuitry. An additional feature that makes it a powerful tool for the analysis of memory processes is that early odor preference learning can be lateralized via single naris occlusion within the critical period. This is due to the lack of mature anterior commissural connections of the olfactory hemispheres at this early age. This work outlines behavioral protocols for lateralized odor learning using nose plugs. Acute, reversible naris occlusion minimizes tissue and neuronal damages associated with long-term occlusion and more aggressive methods such as cauterization. The lateralized odor learning model permits within-animal comparison, therefore greatly reducing variance compared to between-animal designs. This method has been used successfully to probe the circuit changes in the olfactory system produced by training. Future directions include exploring molecular underpinnings of odor memory using this lateralized learning model; and correlating physiological change with memory strength and durations.

This protocol introduces lateralized early odor preference learning in rats using acute single naris occlusion. Lateralized learning permits the examination of behavioral outcomes and underpinning biological mechanisms within the same animals, reducing variance induced by between-animal designs. This protocol can be used to investigate molecular mechanisms underpinning early odor learning.

Rat pups during a critical postnatal period (&#8804; 10 days) readily form a preference for an odor that is associated with stimuli mimicking maternal ...

Partial Optic Nerve Transection in Rats: A Model Established with a New Operative Approach to Assess Secondary Degeneration of Retinal Ganglion Cells

Previous studies have shown that the secondary degeneration of retinal ganglion cells (RGCs) occurs commonly in glaucoma. Partial optic nerve transection is considered a useful and reproducible model. Compared with other optic nerve injury models used commonly for assessing secondary degeneration, e.g. complete optic nerve transection and optic nerve crush models, the partial optic nerve transection model is superior as it distinguishes primary from secondary degeneration in situ. Therefore, it serves as an excellent tool for evaluating secondary degeneration. This study describes a novel operative approach of partial optic nerve transection by directly accessing the area of the retrobulbar optic nerve through the orbital lateral wall of the eyeball. Moreover, we present a newly designed, low cost surgical instrument to assist with transection. As demonstrated by the representative results in distinguishing the boundary of primary and secondary injury areas, the new approach and instrument ensures high efficiency and stability of the model by providing adequate space for surgical operation. This in turn makes it easy to separate the meningeal sheath and ophthalmic vessels from the optic nerve before transection. An additional benefit is that this space-saving operative approach improves the investigators&#39; ability to administer drugs, carriers, or selective RGC tracers to the stump of the partially transected optic nerve, allowing the exploration of mechanisms behind secondary injury in RGCs, in a new way.

Secondary degeneration of retinal ganglion cells (RGCs) occurs commonly in glaucoma. This study describes an innovative operative approach for partial optic nerve transection. The use of this space-saving operative approach extends the model's application range, and allows exploration of secondary injury mechanisms in RGCs in a new way.

Previous studies have shown that the secondary degeneration of retinal ganglion cells (RGCs) occurs commonly in glaucoma. Partial optic nerve transection ...

Sub-acute Cerebral Microhemorrhages Induced by Lipopolysaccharide Injection in Rats

Cerebral microhemorrhages (CMHs) are common in aged patients and are correlated to various neuropsychiatric disorders. The etiology of CMHs is complex, and neuroinflammation is often observed as a co-occurrence. Here, we describe a sub-acute CMHs rat model induced by lipopolysaccharide (LPS) injection, as well as a method for detecting CMHs. Systemic LPS injection is relatively simple, economical, and cost-effective. One major advantage of LPS injection is its stability to induce inflammation. CMHs caused by LPS injection could be detected by gross observation, hematoxylin and eosin (HE) staining, Perl&#39;s Prussian staining, Evans blue (EB) double-labeling, and magnetic resonance imaging-susceptibility weighted imaging (MRI-SWI) technology. Finally, other methods of developing CMHs animal models, including their advantages and/or disadvantages, are also discussed in this report.

We present a protocol to induce and detect CMHs caused by LPS injection in Sprague-Dawley rats, which may be utilized in future research investigations on the pathogenesis of CMHs.

Cerebral microhemorrhages (CMHs) are common in aged patients and are correlated to various neuropsychiatric disorders. The etiology of CMHs is complex, ...