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 ster...

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H., 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=Incomplete+bladder+emptying+in+patients+with+stroke:+is+detrusor+external+sphincter+dyssynergia+a+potential+cause.">Incomplete bladder emptying in patients with stroke: is detrusor external sphincter dyssynergia a potential cause.</a> Archives of Physical Medicine and Rehabilitation. 91 (7), 1105-1109 (2010).</li><li>FitzGerald, M. P., Brubaker, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+etiology+of+urinary+retention+after+surgery+for+genuine+stress+incontinence.">The etiology of urinary retention after surgery for genuine stress incontinence.</a> Neurourology and Urodynamics. 20 (1), 13-21 (2001).</li><li>Rahman, M., Siddik, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroanatomy,+Pontine+Micturition+Center.">Neuroanatomy, Pontine Micturition Center.</a> StatPearls. , (2020).</li><li>Wrobel, A., Lancut, M., Rechberger, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+model+of+detrusor+overactivity+in+conscious+rats+induced+by+retinyl+acetate+instillation.">A new model of detrusor overactivity in conscious rats induced by retinyl acetate instillation.</a> Journal of Pharmacological and Toxicological Methods. 74 (7), 16 (2015).</li><li>Rosenzweig, E. S., McDonald, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+for+treatment+of+spinal+cord+injury:+research+trends+and+progress+toward+useful+repair.">Rodent models for treatment of spinal cord injury: research trends and progress toward useful repair.</a> Current Opinion in Neurology. 17 (2), 121-131 (2004).</li><li>Yoo, K. H., Lee, S. 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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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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 ...

Establishing an animal model of DU by conus medullaris transection offers an excellent opportunity for starting the pathophysiology of detrusor underactivity. Our protocol is the first to use conus medullaris transection to induce detrusor underactivity in an animal model. To perform a conus medullaris transection, First, make a three centimeter median skin incision on the back of the animal.Use surgical scissors to deepen the incision through the subcutaneous tissues and excise the muscles attached to the spine To expose the 13th rib. And carefully resect the muscles attached to the spine to expose the vertebral column. Resect the supraspinous, and interspinous ligaments.And use surgical scissors and forceps to expose the spine at L4 to L5.Use Kelly forceps to carefully remove the L4 to L5 vertebral spinous process and parts of the transverse process to expose the spinal cord. And completely expose the conus medullaris at L4 to L5.Use iridectomy scissors to completely transect the conus medullaris. And insert tissue packing to block the recovery of the spinal cord.Then use a 4-0 non-absorbable suture to close the overlying muscle and skin. And place the rat in a 37 degree Celsius incubator for the first hour post-procedure, with monitoring until the animal is sternal or actively moving. Urine retention is observed immediately after surgery, with the peak point of volume appearing on the second day post-operation, and gradually decreasing for about 10 days.Ten days after surgery, the retention volume reaches a steady level. Urodynamic testing reveals that the maximum cytometric capacity and bladder compliance are significantly higher in the test group, while the detrusor opening pressure in the test group decreases significantly compared to the control group. Correctly identifying the 13th rib is a key step for successful identification of the L4 to L5 vertebra.

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1.9K visualizações.  Capital Medical University. Establishing an animal model of DU by conus medullaris transection offers an excellent opportunity for starting the pathophysiology of detrusor underactivity. Our protocol is the first to use conus medullaris transection to induce detrusor underactivity in an animal model. To perform a conus medullaris transection, First, make a three centimeter median skin incision on the back of the animal.Use surgical scissors to deepen the incision through the subcutaneous tissues and excise the mu...