All animal experiments were performed in accordance with the policies of the Tianjin Medical University General Hospital ethical committees. Male Sprague-Dawley rats aged between 9 and 12 weeks, weighing approximately 320-360 g, were used for this study. The details of the reagents and equipment used are listed in the Table of Materials.
1. Animal selection and maintenance
<ol>
	<li>Select a healthy animal (body weight of ~220-240 g).</li>
	<li>Ensure that they meet the criteria of specific pathogen-free (SPF)15 level and are adaptively reared for a minimum of 2 weeks in an environment with adequate ventilation (8 to 12 air changes per hour), a comfortable temperature (20-25 &#176;C), appropriate humidity (40%-70%), minimal noise (below 70 decibels), and a natural light cycle (12 h of light and 12 h of darkness).</li>
	<li>During this period, house them in standard clean cages at a density of three to five per cage, and change the bedding twice weekly. Provide ad libitum access to food and water, as well as standard maintenance feed for laboratory rats.</li>
</ol>
2. Preoperative preparation
<ol>
	<li>Select a healthy rat with an approximate body weight of 320 g to 360 g. Fast the rat for 8-12 h before the operation and provide access to a solution of physiological saline and 5% glucose in a 1:1 ratio for voluntary consumption.</li>
	<li>Prepare the autoclaved microsurgical instruments (preoperative soaking in alcohol for 1 h), a microscope, a rat dissecting table, 8-0 non-absorbable high molecular suture, 4-0 non-absorbable suture, sterile gauze, sterile cotton swabs, etc.</li>
</ol>
3. Establishment of the rat ileal pouch model
<ol>
	<li>Intraperitoneally inject a 1% pentobarbital sodium solution at a dose of 6 mL/kg and incisional infiltration of local anesthesia with 0.5% ropivacaine to anesthetize the rat. Maintain the rat at a comfortable temperature during anesthesia with an electric lamp.</li>
	<li>Perform total colorectal resection following the steps below:
	<ol>
		<li>Secure the rat in dorsal recumbency on an anatomical bench following a satisfactory anesthetic protocol. Confirm the depth of anesthesia via a toe-pinch. Use shaving clippers to eliminate hair debris, and apply iodophor solution twice for surgical field sterilization.</li>
		<li>Make a midline incision, approximately 6 cm long, to dissect through the skin, white line fascia, and peritoneum, providing entry into the abdominal cavity. Use a retractor to expose the peritoneal surface and cover it with bacteriostatic saline-drenched sterile gauze.</li>
		<li>Isolate the vascular flow of the terminal jejunum, ligate its origin using an 8-0 suture thread, and subsequently sever it. Set the cecal stump, located 1-2 cm from the ileocecal valve, at rest, and then sever it.</li>
		<li>Commence right hemicolon resection, ligating the right hemicolon and middle colic vein conservatively.</li>
		<li>Further segregate the inferior mesenteric artery and isolate the inferior rectal artery. Continue isolation down the rectum until an interval equating to two centimeters from the anal verge. Obliquely resect the distal rectum at around 45 degrees to avoid postoperative stenosis.</li>
	</ol>
	</li>
	<li>Perform J pouch construction.
	<ol>
		<li>Use a microtome scalpel to separate the transverse section of the terminal ileum from the mesentery intestine, which should measure about 6-7 cm.</li>
		<li>Fold the terminal ileum in a J-shaped shape to create a pouch for the ileum. Perform posterior wall anastomosis via an interlocking stitch. Augment the anterior wall using a modified Connell stitch and retain an appropriate intestine to match the cross-sectional size of the distal rectal stump.</li>
		<li>Reinforce the J-shaped pouch with 8-0 stitching if needed. The length of the J pouch should fall within the range of 2.5 cm to 3.5 cm.</li>
	</ol>
	</li>
	<li>Perform ileal pouch-anal anastomosis, IPAA.
	<ol>
		<li>Confirm the absence of torsion in the mesentery and suture the ant side walls of the pouch&#39;s opening and the lateral wall of the rectal stump at intervals with an 8-0 suturing thread for traction.</li>
		<li>Ultimately, apply a full-layer continuous lock suture to both the anterior and posterior walls.</li>
		<li>Verify the absence of active bleeding and physiologically cleanse the abdominal cavity with normal saline. Sequentially close the abdominal muscle fascia and skin with 4-0 sutures.</li>
	</ol>
	</li>
	<li>Perform postoperative management.
	<ol>
		<li>Administer ketoprofen as postoperative analgesia (40 mg/kg, subcutaneously) to all the rats after abdominal closure. Ensure that the rat is warmed using an electric lamp until restoration occurs.</li>
		<li>Restrict the animal from food consumption for a minimum period of 72 h postoperatively to reduce the risk of intestinal obstruction. Allow access to a diet of 5% glucose ad libitum to quickly replenish energy and body fluids, and adjust the feeding frequency according to defecation patterns.</li>
		<li>A week after the surgery, begin with limited nourishment and gradually increase the quantity consumed. Then, provide the rats with regular rodent feed to consume freely, while keeping a daily record of their dietary intake, water intake, and body weight.</li>
	</ol>
	</li>
</ol>
4. Establishment of rat ileal pouchitis model with DSS
<ol>
	<li>Perform the experimental grouping.
	<ol>
		<li>Randomly assign 12 rats who have undergone total colorectal resection and IPAA surgery into the IPAA group (Group A, n = 6) and the pouchitis group (Group B, n = 6).</li>
		<li>Prepare a 4% DSS solution by adding 4 g of DSS to 100 mL of pure water, freshly prepared daily.</li>
		<li>Administer the IPAA group and the pouchitis group with pure water or 4% DSS on postoperative day 31 to day 35, respectively. Allow rats to freely drink and eat rat food during the four consecutive days of administration.</li>
	</ol>
	</li>
	<li>Perform the pouch sampling.
	<ol>
		<li>On the morning of day 35, after the operation, anesthetize the rats with an intraperitoneal injection of 1% pentobarbital sodium solution, administering a dose of 6 mL/kg (following institutionally approved protocols).</li>
		<li>Sever the pouch perpendicularly from the stoma of the pouch to the junction of the input and output pouches in each group. Obtain the pouch specimen.</li>
		<li>Open the pouch along the anterior wall suture line and wash the intestinal canal with saline.</li>
		<li>Place a fragment of pouch tissue in a microcentrifuge tube and promptly refrigerate it at -80 &#176;C. Use this part for ELISA detection of inflammatory indicators. Fix the remaining pouch section with 10% formaldehyde for histopathological scoring and immunohistochemical staining.</li>
		<li>Finally, euthanize the rat by air embolism under deep anesthesia (following institutionally approved protocols).</li>
	</ol>
	</li>
</ol>
5. Histological analysis
<ol>
	<li>After acquiring pouch tissue from the rat, immerse it in 4% paraformaldehyde for 24 h. Subsequently, proceed with dehydration and embedding protocols. Section the processed tissue for histological examination16.</li>
	<li>Apply hematoxylin and eosin staining to identify histopathological differences across groups. Examine the samples microscopically and capture photographs for documentation.</li>
</ol>
6. Immunohistochemical assay
<ol>
	<li>Dewax and dehydrate the tissue sections carefully. Then, conduct antigen retrieval by cooling the sections in sodium citrate solution and blocking them with blocking serum for 20 min.</li>
	<li>Subsequently, expose the slices to the primary anti-occludin antibody and incubate them overnight at 4 &#176;C. Afterward, treat them with secondary antibodies for 30 min before hematoxylin counterstaining16.</li>
	<li>Once the slices have dried, observe and photograph them under a light microscope.</li>
</ol>
7. ELISA test
<ol>
	<li>7.1 Mince and homogenize the tissue fragments in lysis buffer using sonication to ensure thorough homogenization. Utilize the resulting supernatant for detection.</li>
	<li>Allocate wells for blanks, samples, and replicates per group. Determine protein concentration by reading the absorbance at 450 nm (OD value) and conducting linear regression analysis16.</li>
</ol>

Experimental Rat Model of Pouchitis for Studying Ulcerative Colitis Pathogenesis and Treatment

<ol>
	<li>Yang, M. L., Brar, M. S., Kennedy, E. D., De Buck Van Overstraeten, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laparoscopic+versus+transanal+IPAA+for+ulcerative+colitis:+A+patient-centered+treatment+trade-off+study.">Laparoscopic versus transanal IPAA for ulcerative colitis: A patient-centered treatment trade-off study.</a> Dis Colon Rectum. 67 (1), 107-113 (2024).</li><li>Aktas, M. K., 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=Current+status+and+surgical+technique+for+restorative+proctocolectomy+with+ileal+pouch-anal+anastomosis.">Current status and surgical technique for restorative proctocolectomy with ileal pouch-anal anastomosis.</a> Balkan Med J. 40 (4), 236-243 (2023).</li><li>Zhao, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbiota+DNA+translocation+into+mesentery+lymph+nodes+is+associated+with+early+development+of+pouchitis+after+ipaa+for+ulcerative+colitis.">Microbiota DNA translocation into mesentery lymph nodes is associated with early development of pouchitis after ipaa for ulcerative colitis.</a> Diseases of the Colon &amp; Rectum. 66 (11), e1107-e1118 (2022).</li><li>Ng, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Worldwide+incidence+and+prevalence+of+inflammatory+bowel+disease+in+the+21st+century:+A+systematic+review+of+population-based+studies.">Worldwide incidence and prevalence of inflammatory bowel disease in the 21st century: A systematic review of population-based studies.</a> Lancet. 390 (10114), 2769-2778 (2017).</li><li>Pardi, D. S., D'haens, G., Shen, B., Campbell, S., Gionchetti, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+guidelines+for+the+management+of+pouchitis.">Clinical guidelines for the management of pouchitis.</a> Inflamm Bowel Dis. 15 (9), 1424-1431 (2009).</li><li>Shen, 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=Treatment+of+pouchitis,+Crohn's+disease,+cuffitis,+and+other+inflammatory+disorders+of+the+pouch:+Consensus+guidelines+from+the+international+ileal+pouch+consortium.">Treatment of pouchitis, Crohn's disease, cuffitis, and other inflammatory disorders of the pouch: Consensus guidelines from the international ileal pouch consortium.</a> Lancet Gastroenterol Hepatol. 7 (1), 69-95 (2022).</li><li>Dalal, R. L., Shen, B., Schwartz, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+of+pouchitis+and+other+common+complications+of+the+pouch.">Management of pouchitis and other common complications of the pouch.</a> Inflamm Bowel Dis. 24 (5), 989-996 (2018).</li><li>Li, K. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+rat+model+of+pouchitis+after+proctocolectomy+and+ileal+pouch-anal+anastomosis+using+2,4,6-trinitrobenzene+sulfonic+acid.">A new rat model of pouchitis after proctocolectomy and ileal pouch-anal anastomosis using 2,4,6-trinitrobenzene sulfonic acid.</a> J Gastrointest Surg. 25 (6), 1524-1533 (2021).</li><li>Drzymala-Czyz, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discrepancy+between+clinical+and+histological+effects+of+dha+supplementation+in+a+rat+model+of+pouchitis.">Discrepancy between clinical and histological effects of dha supplementation in a rat model of pouchitis.</a> Folia Histochem Cytobiol. 50 (1), 125-129 (2012).</li><li>Santiago, P., Barnes, E. L., Raffals, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classification+and+management+of+disorders+of+the+J+pouch.">Classification and management of disorders of the J pouch.</a> Am J Gastroenterol. 118 (11), 1931-1939 (2023).</li><li>Lichtman, S. N., Wang, J., Hummel, B., Lacey, S., Sartor, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rat+model+of+ileal+pouch-rectal+anastomosis.">A rat model of ileal pouch-rectal anastomosis.</a> Inflamm Bowel Dis. 4 (3), 187-195 (1998).</li><li>Guarner, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inulin+and+oligofructose:+Impact+on+intestinal+diseases+and+disorders.">Inulin and oligofructose: Impact on intestinal diseases and disorders.</a> Br J Nutr. 93, S61-S65 (2005).</li><li>Kim, C. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=L-tryptophan+exhibits+therapeutic+function+in+a+porcine+model+of+dextran+sodium+sulfate+(DSS)-induced+colitis.">L-tryptophan exhibits therapeutic function in a porcine model of dextran sodium sulfate (DSS)-induced colitis.</a> J Nutr Biochem. 21 (6), 468-475 (2010).</li><li>Valatas, V., Bamias, G., Kolios, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+colitis+models:+Insights+into+the+pathogenesis+of+inflammatory+bowel+disease+and+translational+issues.">Experimental colitis models: Insights into the pathogenesis of inflammatory bowel disease and translational issues.</a> Eur J Pharmacol. 759, 253-264 (2015).</li><li>Letson, H. L., Morris, J., Biros, E., Dobson, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conventional+and+specific-pathogen+free+rats+respond+differently+to+anesthesia+and+surgical+trauma.">Conventional and specific-pathogen free rats respond differently to anesthesia and surgical trauma.</a> Sci Rep. 9 (1), 9399 (2019).</li><li>Gu, Y., 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=Saccharomyces+boulardii,+a+yeast+probiotic,+inhibits+gut+motility+through+upregulating+intestinal+serotonin+transporter+and+modulating+gut+microbiota.">Saccharomyces boulardii, a yeast probiotic, inhibits gut motility through upregulating intestinal serotonin transporter and modulating gut microbiota.</a> Pharmacol Res. 181, 106291 (2022).</li><li>Akiyama, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+phenotype+of+the+j+pouch+in+patients+with+inflammatory+bowel+disease:+A+new+classification+for+pouch+outcomes.">Endoscopic phenotype of the j pouch in patients with inflammatory bowel disease: A new classification for pouch outcomes.</a> Clin Gastroenterol Hepatol. 20 (2), 293-302 (2022).</li><li>Hata, K., 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=Pouchitis+after+ileal+pouch-anal+anastomosis+in+ulcerative+colitis:+Diagnosis,+management,+risk+factors,+and+incidence.">Pouchitis after ileal pouch-anal anastomosis in ulcerative colitis: Diagnosis, management, risk factors, and incidence.</a> Dig Endosc. 29 (1), 26-34 (2017).</li><li>Gallo, G., Kotze, P. G., Spinelli, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgery+in+ulcerative+colitis:+When?+How.">Surgery in ulcerative colitis: When? How.</a> Best Pract Res Clin Gastroenterol. 32-33, 71-78 (2018).</li><li>Parks, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proctocolectomy+without+ileostomy+for+ulcerative+colitis.">Proctocolectomy without ileostomy for ulcerative colitis.</a> BMJ. 2, 85-88 (1978).</li><li>Shebani, K. O., 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=Pouchitis+in+a+rat+model+of+ileal+J+pouch-anal+anastomosis.">Pouchitis in a rat model of ileal J pouch-anal anastomosis.</a> Inflamm Bowel Dis. 8 (1), 23-34 (2002).</li></ol>

Ulcerative colitis (UC) is a chronic intestinal inflammation characterized by recurrent epigastric pain, diarrhea, and mucus bloody stool. It primarily affects the rectum and may involve the progressing colon to varying degrees. Surgery plays a crucial role in managing UC17,18,19. Since Parks et al.20 introduced total colectomy with an ileal pouch-anal anastomosis (IPAA) procedure in 1978 to remove altere...

Pouchitis is a non-specific inflammation that affects the ileal pouch and is a prevalent complication following total proctocolectomy and ileal pouch-anal anastomosis (IPAA) in individuals with ulcerative colitis (UC)1,2,3. This condition has a relatively high occurrence rate of up to 50% and can cause various clinical manifestations, including diarrhea, abdominal pain, fecal blood loss, and fever. The exact cause of pouchitis remains elusive, although some researchers believe that a shift in the pouch flora may trigger immune activation and subsequent inflammation4,5,6,7.
Due to the challenges associated with conducting clinical trials on pouchitis, animal models can serve as valuable tools for studying pouchitis drugs and mechanisms. There are growing concerns regarding the creation of rat ileal pouches, with reports indicating possible inflammation8. However, research in this field remains sparse due to the intricate nature of the manufacturing process, which lacks clear guidelines9,10. In 1998, Lichtman was the first to establish an ileal pouch model in Lewis rats and Sprague-Dawley (SD) rats by performing total colectomy11. They observed macrophage infiltration, mucosal ulceration, and an increase in anaerobic bacterial flora within the intestines of these rats, providing a solid foundation for further research on ileal pouch inflammation. This experimental model of rat pouchitis closely mimics the physical signs and underlying mechanisms observed in human pouchitis.
Commonly applied preclinical ulcerative colitis models include the DSS and TNBS models. The inducing chemical 2,4,6-trinitrobenzene sulfonic acid (TNBS) typically simulates Crohn&#39;s disease12. The DSS model, respected for its efficacy, safety profile, and affordability, is often used as a reliable tool for UC induction due to the evident symptoms observed. Given the colonization of the pouch tissue, we successfully induced a pouchitis model using DSS13,14.
In the present study, microsurgery was used to successfully create an ileal pouch model in experimental rats via IPAA surgery. Subsequently, a sustained rat pouchitis model was established by inducing inflammation of the ileal pouch with DSS. Accuracy during surgery is essential for successful model formation, and postoperative care is crucial as well. This model can be used to investigate the pathogenesis of pouchitis, evaluate potential therapeutic agents, and further our understanding of this complex condition. The study streamlines the ileal pouch manufacturing procedure, reducing operation duration and boosting efficiency, thereby establishing a robust foundation for fundamental research into postsurgical pouch disorders.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anhydrous ethanol</td>
			<td>Tianjin Fengchuan Chemical Reagent Technology Co., Ltd</td>
			<td>China</td>
			<td>Hematoxin-eosin Staining</td>
		</tr>
		<tr>
			<td>Dextran Sulfate Sodium&#160;</td>
			<td>&#160;Yeasen&#160;</td>
			<td>60316ES76</td>
			<td>Used to induce pouch inflammation</td>
		</tr>
		<tr>
			<td>Formaldehyde solution</td>
			<td>Tianjin Zhiyuan Reagent Company</td>
			<td>China</td>
			<td>Hematoxin-eosin Staining</td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Jiangxi Zhonggan Medical Equipment Company</td>
			<td>China</td>
			<td>Used for animal microsurgery</td>
		</tr>
		<tr>
			<td>Hematoxylin</td>
			<td>Beijing Zhongshan Jinqiao Company</td>
			<td>China</td>
			<td>Hematoxin-eosin Staining</td>
		</tr>
		<tr>
			<td>Interferon &#947;&#160; Detection reagent kit</td>
			<td>Cloud-clone</td>
			<td>SEA049Ra</td>
			<td>Detecting inflammatory factors</td>
		</tr>
		<tr>
			<td>Interleukin-10 detection kit</td>
			<td>Cloud-clone</td>
			<td>SEA056Ra</td>
			<td>Detecting inflammatory factors</td>
		</tr>
		<tr>
			<td>Interleukin-17 detection kit</td>
			<td>Cloud-clone</td>
			<td>SEA063Ra</td>
			<td>Detecting inflammatory factors</td>
		</tr>
		<tr>
			<td>Interleukin-6 detection kit</td>
			<td>Cloud-clone</td>
			<td>SEA079Ra</td>
			<td>Detecting inflammatory factors</td>
		</tr>
		<tr>
			<td>Iodophor</td>
			<td>Tangpai Medical Equipment Co., Ltd</td>
			<td>China</td>
			<td>Used for animal microsurgery</td>
		</tr>
		<tr>
			<td>Microscopic manipulation instruments</td>
			<td>Aesculap</td>
			<td>Germany</td>
			<td>Used for animal microsurgery</td>
		</tr>
		<tr>
			<td>Occludin</td>
			<td>abcam</td>
			<td>ab216327</td>
			<td>Immunohistochemical testing</td>
		</tr>
		<tr>
			<td>Sewing needle</td>
			<td>Yangzhou Fuda Medical Equipment Co., Ltd</td>
			<td>China</td>
			<td>Used for animal microsurgery</td>
		</tr>
		<tr>
			<td>tumor necrosis factor &#945; Detection reagent kit</td>
			<td>Cloud-clone</td>
			<td>SEA133Ra</td>
			<td>Detecting inflammatory factors</td>
		</tr>
		<tr>
			<td>Two person binocular surgical microscope</td>
			<td>OPTON</td>
			<td>Germany</td>
			<td>Used for animal microsurgery</td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>Tianjin Yingda Rare and Precious Reagent Factory</td>
			<td>China</td>
			<td>Hematoxin-eosin Staining</td>
		</tr>
	</tbody>
</table>

a rat model of pouchitis following proctocolectomy and ileal pouch-anal anastomosis using dextran sulfate sodium

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing lifelong morbidity. When medical treatment is ineffective, especially in cases of massive gastrointestinal bleeding, perforation, toxic megacolon, or carcinogenesis, surgery becomes the last line of defense to cure UC. Total colorectal resection and ileal pouch-anal anastomosis (IPAA) offer the best chance for long-term treatment. Pouchitis is the most common and troublesome postoperative complication. In this investigation, microsurgery is employed to create an ileal pouch model in experimental rats via IPAA surgery. Subsequently, a sustained rat model of pouchitis is established by inducing inflammation of the ileal pouch with dextran sulfate sodium (DSS). The successful establishment of rat pouchitis is validated through analysis of postoperative general status, weight, food and water intake, fecal data, as well as pouch tissue pathology, immunohistochemistry, and inflammatory factor analysis. This experimental animal model of pouchitis provides a foundation for studying the pathogenesis and treatment of the condition.

Author Spotlight: Developing a Rat Model for Pouchitis Research and Treatment

A Rat Model of Pouchitis Following Proctocolectomy and Ileal Pouch-Anal Anastomosis Using Dextran Sulfate Sodium

Due to the challenges associated with conducting clinical trials on pouchitis, animal models can serve as valuable tools for studying pouchitis drugs and their mechanisms. This protocol describes the method for establishing a rat model of pouchitis. This experimental animal model of pouchitis provides a foundation for studying the pathogenesis and the treatment of the condition.With previous experience in mouse feeding and IPAA surgery modeling, compressing the learning curve down to around 10 subjects is feasible. A critical step in this process is construction and anastomosis of the J-pouch. Postoperative management also play a pivotal role in successful modeling.The successful establishment of the rat pouchitis model provide a solid platform for subsequent drug and mechanism research. Our team will always be committed to studying the pathogenesis of pouchitis and the mechanism of therapeutic drugs.

General condition evaluation of ileal pouch model rats after establishment 
After the operator passed the IPAA surgical learning curve, the rats tolerated the surgery well, with a surgical duration of 192.94 min &#177; 27.15 min, and fewer postoperative complications occurred. During the early postoperative period, rats experienced a decrease in dietary intake, but their preoperative appetite was restored within 10 days to 14 days after surgery. Early postoperative activity slightly decreased, and t...

This protocol describes the method for establishing a rat model of pouchitis. The ileal pouch model was created by performing ileal pouch-anal anastomosis (IPAA) surgery using microsurgical techniques. After the surgery, the rat was treated with 4% dextran sulfate sodium (DSS) for 4 days.

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing ...

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229 Views.  Tianjin Medical University General Hospital. Due to the challenges associated with conducting clinical trials on pouchitis, animal models can serve as valuable tools for studying pouchitis drugs and their mechanisms. This protocol describes the method for establishing a rat model of pouchitis. This experimental animal model of pouchitis provides a foundation for studying the pathogenesis and the treatment of the condition.With previous experience in mouse feeding and IPAA surgery modeling, compressing the learning curve down to a...

Video: Author Spotlight: Developing a Rat Model for Pouchitis Research and Treatment

Establishment of the Rat Ileal Pouch Model Using Microsurgical Techniques

To begin, position the rat on its back in dorsal recumbency on an anatomical bench. Cover the surgical site with sterile gauze soaked in bacteriostatic saline. After creating a six-centimeter midline incision, reveal the peritoneal surface using a retractor.Then, cut the terminal jejunum. Position the cecal stump one to two centimeters from the ileocecal valve and then cut it. Isolate the blood supply to the terminal jejunum and tie it off with an 8-0 suture thread.Now, begin the resection of the right hemicolon, carefully tying off the right hemicolon and middle colic vein. Next, separate the inferior mesenteric artery and isolate the inferior rectal artery. Proceed to isolate down the rectum until reaching two centimeters from the anal verge.Then, cut the distal rectum at an angle of approximately 45 degrees to prevent postoperative narrowing. Then, fold the terminal ileum into a J shape to create a pouch for the ileum. Using an interlocking stitch, perform posterior wall anastomosis and enhance the anterior wall with a modified Connell stitch.Ensure there is no torsion in the mesentery. At intervals, suture the anterior side walls of the pouch's opening and the lateral wall of the rectal stump using an 8-0 suturing thread for traction. Then, apply a full layer continuous lock suture to both the anterior and posterior walls.Sequentially close the abdominal muscle fascia and skin using 4-0 sutures. To treat the rat ileal pouchitis model with DSS, dissolve four grams of DSS in 100 milliliters of pure water, freshly prepared daily. Administer pure water to the IPAA group and 4%DSS to the pouchitis group from postoperative day 31 to day 35.Initially, both the IPAA and ileal pouchitis groups had equal body weights and were generally in good condition. By the 35th day after surgery, the weight of the ileal pouchitis group was significantly lower than that of the IPAA group.