Colectomy In Rats Research Articles

Spillage of bacterial products during colon surgery increases the risk of liver metastases development in a rat colon carcinoma model.

ABSTRACTSurgical resection of the primary tumor provides the best chance of cure for patients with colorectal carcinoma (CRC). However, bacterial translocation during intestinal surgery has been correlated with poor long-term oncological outcome. Therefore, we investigated the influence of bacterial contamination during colon surgery on CRC liver metastases development. Blood and liver samples of patients undergoing resection of primary CRC or liver metastases were collected. Cell numbers, activation markers and inflammatory mediators were determined. Tumor cell adhesion and outgrowth after sham- or colectomy operations were determined in a rat model, in which tumor cells had been injected into the portal vein.White blood cells and granulocytes were increased in per- and post-operative patient blood samples. IL-6 was also increased post-operatively compared to the preoperative level. Expression of NOX-2, NOX-4 and polymorphonuclear cells (PMNs) numbers were elevated in post-operative human liver samples. In vitro stimulation of macrophages with plasma of rats after colectomy resulted in production of reactive oxygen species (ROS). Colectomy in rats increased D-lactate levels in plasma, supporting bacterial translocation. Decreased expression of tight junction molecules and increased tumor cell adhesion and outgrowth was observed. Treatment with a selective decontamination of the digestive tract (SDD) cocktail decreased tumor cell adherence after colectomy.In conclusion, postoperative bacterial translocation may activate liver macrophages and PMNs, resulting in ROS production. As we previously showed that ROS release led to liver vasculature damage, circulating tumor cells may adhere to exposed extracellular matrix and grow out into liver metastases. This knowledge is pivotal for development of therapeutic strategies to prevent surgery-induced liver metastases development.

Reducing Colorectal Anastomotic Leakage with Tissue Adhesive in Experimental Inflammatory Bowel Disease

Anastomotic leakage after gastrointestinal surgery remains a challenging clinical problem. This study aimed to investigate the effectiveness of TissuCol (fibrin glue), Histoacryl Flex (n-butyl-2-cyanoacrylate), and Duraseal (polyethylene glycol) on colorectal anastomotic healing during experimental colitis. We first performed colectomy 7 days after 10 mg trinitrobenzene sulfonic acid (TNBS)-induced colitis to validate a rat TNBS-colitis-colectomy model. Subsequently, this TNBS-colitis-colectomy model was used in 73 Wistar rats that were stratified into a colitis group (CG, no adhesive), a TissuCol group (TG), a Histoacryl group (HG), and a Duraseal group (DG). Anastomotic sealant was applied with one adhesive after constructing an end-to-end hand-sewn anastomosis. Clinical manifestations, anastomotic bursting pressure, and immunohistochemistry of macrophage type-one (M1) and type-two (M2) was performed on postoperative day (POD)3 or POD7. TNBS-caused mucosal and submucosal colon damage and compromised anastomotic healing (i.e., abscess formation and low anastomotic bursting pressure). On POD3, higher severity of abscesses was seen in CG. Average anastomotic bursting pressure was 53.2 ± 35.5 mm Hg in CG, which was significantly lower than HG (134.4 ± 27.5 mm Hg) and DG (95.1 ± 54.3 mm Hg) but not TG (83.4 ± 46.7 mm Hg). Furthermore, a significantly higher M2/M1 index was found in HG. On POD7, abscesses were only seen in CG (6/9) but not in other groups; HG had the lowest severity of adhesion. We describe the first surgical IBD model by performing colectomy in rats with TNBS-induced colitis, which causes intra-abdominal abscess formation and compromises anastomotic healing. Anastomotic sealing with Histoacryl Flex prevents these complications in this model. Alternative activation of macrophages seems to be involved in its influence on anastomotic healing.

Changes of glucagon-like peptide-2 expression in serum and ileum after colectomy in rats

Objective To explore the effect of colectomy on the expression of glucagon-like peptide-2(GLP-2) in serum and ileum and compare the changes of GLP-2 after different colectomy in rats. Methods Eighty male or female rats, aging 3-4 months old, were recruited in this study.The rats weight 180-250 g. The 80 rats were evenly and randomly distributed into 4 groups according to the surgical procedures they underwent: control group, in which the rats were not performed any procedures; sham surgery group, in which the rats underwent laparotomy; left hemicolectomy group, in which the rats were performed left hemicolectomy; and subtotal colectomy group, in which the rats were performed subtotal colectomy.According to execution time, each group had 4 subgroups, including 0 day group, 10 day group, 20 day group and 30 day group, and 5 rats were included in each subgroup.The whole blood was collected through cardiac puncture.Serum was collected and GLP-2 in serum was determined by enzyme-linked immunosorbent assay.The GLP-2 in ileum was studied by immunohistochemistry staining.The length of villus of ileum was also mea-sured by HE staining. Results The protein of GLP-2 was found in fibroblasts, epithelium and endocrine cells in ileum.Compared with control group and sham surgery group, the expressions of GLP-2 in serum and ileum increased significantly in the rats that underwent left hemicolectomy after surgery(all P 0.05). Conclusions The expressions of GLP-2 in serum and ileum are elevated after left hemicolectomy but not in subtotal colectomy, which may be related to the delayed intestinal adaption after colectomy. Key words: Glucagon-like peptide-2; Colectomy; Intestinal adaption

Enhanced aquaporin 8 expression after subtotal colectomy in rat

Background: Aquaporins (AQPs), the family of water-selective channels, are localized in various organs and tissues, including the gastrointestinal (GI) tract. However, the roles of AQPs in the GI tract remain unclear. Materials and Methods: Male SD rats were subjected to subtotal colectomy (Group C, n = 22) or a sham operation (Group S, n = 16) and were sacri-ficed on postoperative days 7, 14, and 28. Total RNAs from the distal ileum and rectum were extracted. Quantitative RT-PCR was performed to measure AQP8 mRNA expression. For light-microscopy or immunohistochemistry, paraffin-embedded sections of 4 μm were prepared with H-E staining or anti-AQP8 antibody reaction. Mann-Whitney U-test was performed to compare the AQP8 distributions between the two groups, and the statistical significance was defined as p

Biodistribution of technetium-99m pertechnetate after total colectomy in rats

This study evaluated the effects of total colectomy on the biodistribution of technetium-99m pertechnetate ((99m)TcO(4)(-)) on the 28th postoperative day in rats. Samples of several organs were harvested for counting the percent of injected radioactivity/g of tissue (%ATI/g). The %ATI/g in colectomy rats was higher in the stomach and ileum than in sham and controls (p<0.05). Increase in mucosa and muscularis size of ileum was observed. Colectomy was associated with lower biodistribution in bladder and thyroid, T3, and T4, than in controls.

Molecular analysis of colonic transformation in the ileum after total colectomy in rats

Colonic transformation is thought to be a phenotypic alteration in the ileum after total colectomy (TC) but has not been well addressed at the molecular level. We previously demonstrated roles of aldosterone in enhancement of ileal sodium absorption after TC. However, the significance of aldosterone in intestinal adaptation has been unknown. Rat epithelial gene expression was compared between the ileum and distal colon by complementary DNA microarray. Genes were categorized into "colonic," "common," and "ileal" genes according to signal intensity. Ileal gene expressions in (1) the control and TC rats and (2) the control and aldosterone-infused rats were compared to detect altered genes or to assess the role of aldosterone in intestinal adaptation. Differential expression of MUC3 and lysozyme was confirmed by quantitative reverse transcriptase-polymerase chain reaction. A total of 6109 genes were categorized into "colonic," "common," or "ileal" gene pools. A comparison of the control and TC rats yielded 82 and 91 genes that were induced and suppressed in the ileum after TC, respectively. Thirty-five percent of them were associated with colonlike transformation (ie, the induction of colonic genes or the suppression of ileal genes). The expressions of MUC3 and lysozyme messenger RNAs were enhanced significantly in the TC ileum, compared with the control. In comparison, aldosterone infusion modulated a total of only 21 genes in the ileum. Those data demonstrate that altered gene expression after TC is, in part, characterized by colonlike transformation. Furthermore, circulating aldosterone appears to play a part in the altering and/or adapting of gene expression in intestinal epithelium.

Induction of 11β-hydroxysteroid dehydrogenase type 2 and hyperaldosteronism are essential for enhanced sodium absorption after total colectomy in rats

Background Patients who undergo total colectomy with ileopouch anal reconstruction often have persistent diarrhea and frequent bowel movements. Analysis of the intestinal adaptation after total colectomy may lead to developing novel therapies for postoperative diarrhea. Methods Sprague-Dawley rats underwent total colectomy with ileoanal reconstruction and were sacrificed 4 and 8 weeks later. Mucosal response to aldosterone was evaluated with the use of ileal mucosa in an Ussing chamber by measuring short circuit current after in vitro stimulation with aldosterone. We investigated the expression of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD 2) in intestinal epithelial cells. To examine the role of hyperaldosteronism, we also evaluated rats treated with a sodium-deficient diet or subcutaneous aldosterone infusion. Results Aldosterone levels increased 80-fold after total colectomy. A comparable amount of aldosterone dramatically increased aldosterone-mediated, amiloride-sensitive short circuit current in the mucosa from colectomized rats, but not in control rats. We measured an increase in 11β-HSD 2 messenger RNA and protein in the distal ileum from colectomized rats. Circulating aldosterone appears to be essential for these functional and molecular changes because similar results were obtained by using the mucosa from both dietary sodium–depleted and aldosterone-infused rats. Conclusions Induction of 11β-HSD 2 is essential for enhanced mineralocorticoid action in the remnant ileum after total colectomy in rats.

Amiloride sensitive Na + channel expression in the ileum after total colectomy in rats

Amiloride sensitive Na + channel expression in the ileum after total colectomy in rats

Pancreatic Trophism Following Colectomy in Rats

It has been shown that the large bowel contains substances with a potential to inhibit exocrine pancreatic function. Following large bowel removal in rats, there is an increase of pancreatic weight, digestive enzyme concentration, and secretion capacity in vitro. To evaluate the role of various GI hormones in the exocrine pancreatic adaptation following colectomy, we measured plasma cholecystokinin (CCK), neurotensin, glucagon, and insulin after meal stimulation. The test meal was applied via a transabdominal gastric tube in eight colectomized Wistar rats after a median of 18 days following surgery. Ten rats with a gastric tube without previous bowel surgery served as controls. After large bowel removal, there was impaired glucose tolerance and attenuated plasma insulin secretion. Baseline plasma glucagon levels were increased after colon removal, whereas the total postprandial glucagon release was decreased. Baseline and postprandial neurotensin values were comparable in both the experimental and control animals. Baseline and postprandial CCK plasma levels were intensely increased in the colectomized rats. It is assumed that the baseline and postprandial CCK pattern in rats after subtotal colectomy is responsible for exocrine pancreatic adaptation.

Subtotal colectomy in the dimethylhydrazine-treated rat. A surgical model of colorectal cancer.

The effects of subtotal colectomy on the survival of rats with established colon cancer induced by 1,2-dimethylhydrazine (DMH) have been investigated in an attempt to assess whether it might provide a suitable model of surgical treatment of this disease. 40 female Wistar rats received a regimen of DMH injections (40 mg/kg body weight s.c. every 14 days for 10 weeks) known to produce colon cancer. An additional 10 rats received no DMH, serving as controls (group 1). After presenting with signs of colonic disease at 25 weeks, all DMH-treated rats had diagnostic colonoscopy under general anaesthesia, only those with visible neoplasms (n = 34) being included in the study. These were randomised into two groups: group 2 (n = 13) animals were unoperated controls while group 3 (n = 21) animals had a therapeutic subtotal colectomy with histological confirmation of cancer in the resected colon. The animals were observed until death, the postoperative survival and cause of death at necropsy being compared between groups. The results showed that overall survival (p less than 0.013) and survival from death due to colon cancer (p less than 0.001) were significantly increased in the colectomised group 3 animals compared to unoperated controls (group 2). While 91% of the unoperated controls died of colon cancer, only 8% of the colectomised group died of this cause (p less than 0.001), the remainder dying from unrelated causes, predominantly DMH-induced primary extracolonic cancers. Subtotal colectomy in rats with DMH-induced colon cancer reduces mortality from this disease, providing a suitable model of surgical treatment. However, the high incidence of DMH-induced extracolonic cancers may make the model unsuitable for studies of adjuvant therapy.

Small-Bowel Adaptation after Colectomy in Rats

Colectomy with ileoproctostomy or ileostomy was performed in rats. The animals were killed at different time intervals after operation. In histological sections from the small intestine the total crypt cell number and vinblastine-arrested mitoses were counted, and the villus height was measured; these parameters were compared with the corresponding ones in unoperated controls and in rats subjected to ileal transection. After ileoproctostomy the rats remained in good condition, whereas ileostomy was followed by weight loss, debility and a great mortality. After ileoproctostomy, ileostomy and ileal transection there was an increased number of mitoses in the crypts during the 28 days' observation period, indicating an increased rate of cell proliferation. Increased villus height was observed after ileoproctostomy as well as after ileostomy. The mucosal hyperplasia may play a role for the increase in water and salt absorption capacity after colectomy. Probably, however, the hyperplasia of the small-intestinal mucosa cannot fully compensate for the loss of the colon in rats. Preservation of the absorptive function of the rectum, as in ileoproctostomy, is necessary for adequate water and salt absorption.

The effect of total colectomy on morphology and absorptive capacity of ileum in the rat

The mechanism of adaptation of intestinal absorption after colectomy has not been established. This adaptation was studied by measuring morphologic changes and absorptive capacity of the ileum before and 2 months after total colectomy and ileoproctostomy in rats. The water-absorptive capacity of ileum was determined in situ by infusing a 10-cm. segment at 0.2 ml./minute with an isotonic solution with a nonabsorbable marker. Net water absorption in the ileum increased from 0.17 ± 0.012 ml./cm./hour in preoperative and control animals to 0.28 ± 0.034 ml./cm./hour 2 months after colectomy (P < 0.01). Average ileal villus length increased 42% and the number of mucosal cells from crypt to tip of villus increased 51%. These findings indicate that both ileal absorptive surface and absorptive capacity increase after total colectomy in the rat and suggest that the enhancement of water-absorptive capacity in the intestinal remnant is the mechanism of functional adaptation after colectomy.