Ursodeoxycholic acid ameliorates ibuprofen-induced enteropathy in the rat

Ursodeoxycholic acid protects neonatal rats from necrotizing enterocolitis: a biochemical, histopathological, and immunohistochemical study

BACKGROUND

The pathophysiology of necrotizing enterocolitis (NEC) includes the massive production of endogenous cytokines with exaggerated activation of inflammatory pathways. Ursodeoxycholic acid (UDCA) has been used as an anti-inflammatory, antioxidant, and anti-apoptotic agent. We investigated the possible protective effects of UDCA in a neonatal rat pup model of NEC.

METHODS

We randomly divided rat pups into three groups: a control group, a non-treated NEC group, and a UDCA-treated NEC group. We induced NEC by feeding formula enterally and via hypoxia/reoxygenation. Intestinal samples were collected for histopathological and immunohistochemical evaluation. Blood samples were taken for biochemical analyses.

RESULTS

UDCA significantly reduced the extents of terminal ileal and jejunal injuries compared to the NEC group (p < .01), reduced Bax and caspase-3 immunoreactivities (both p < .01), and lowered serum levels of platelet-activating factor and intestinal fatty acid-binding protein (p < .01, p = .023, respectively).

CONCLUSIONS

In a rat model of NEC, UDCA protects against adverse intestinal histological, immunohistochemical, and biochemical changes. UDCA significantly reduces the effects of NEC on the rat pup intestine.

Ursodeoxycholic acid attenuates 5-fluorouracil-induced mucositis in a rat model

Intestinal mucositis is a commonly encountered complication of chemotherapy. However, there are few effective treatments or preventive methods. Ursodeoxycholic acid (UDCA) stabilizes cell membranes, acts as an antioxidant and inhibits apoptosis, thereby exerting cytoprotective effects. The aim of the present study was to examine the ability of UDCA to protecting against chemotherapy-associated mucositis. Sprague-Dawley rats were randomly assigned to five groups: Control, vehicle + 5-fluorouracil (5-FU), 5-FU + UDCA (10 mg/kg/day), 5-FU + UDCA (100 mg/kg/day) and 5-FU + UDCA (500 mg/kg/day). Following randomization, a single dose of 5-FU was injected and varying amounts of UDCA was administered to each group. UDCA was administered orally to rats for 6 days, beginning 1 day prior to 5-FU administration. The rats were sacrificed 1 day following the last UDCA administration and intestinal tissue specimens were prepared for analysis. UDCA administration attenuated body weight loss, decreased inflammatory cytokine levels and curbed intestinal villus damage in the 10 and 100 mg/kg/day groups. When compared with the jejunal villi lengths in the vehicle+5-FU group (212.8±58.0 µm), those in the 5-FU + UDCA (10 mg/kg/day) and 5-FU + UDCA (100 mg/kg/day) groups were significantly greater [331.3±18.0 µm (P=0.001) and 310.0±112.6 µm (P=0.046), respectively]. Tumor necrosis factor-α and interleukin-6 levels were reduced in the 10 and 100 mg/kg/day UDCA groups (P<0.05). UDCA considerably attenuated the elevation in inflammatory cytokines and intestinal villus damage. The results of the study suggest that UDCA may be used as a protective agent against chemotherapy-associated intestinal mucositis.

Mechanisms of Damage to the Gastrointestinal Tract From Nonsteroidal Anti-Inflammatory Drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) can damage the gastrointestinal tract, causing widespread morbidity and mortality. Although mechanisms of damage involve the activities of prostaglandin-endoperoxide synthase 1 (PTGS1 or cyclooxygenase [COX] 1) and PTGS1 (COX2), other factors are involved. We review the mechanisms of gastrointestinal damage induction by NSAIDs via COX-mediated and COX-independent processes. NSAIDs interact with phospholipids and uncouple mitochondrial oxidative phosphorylation, which initiates biochemical changes that impair function of the gastrointestinal barrier. The resulting increase in intestinal permeability leads to low-grade inflammation. NSAID inhibition of COX enzymes, along with luminal aggressors, results in erosions and ulcers, with potential complications of bleeding, protein loss, stricture formation, and perforation. We propose a model for NSAID-induced damage to the gastrointestinal tract that includes these complex, interacting, and inter-dependent factors. This model highlights the obstacles for the development of safer NSAIDs.

Cattle bile aggravates diclofenac sodium-induced small intestinal injury in mice

Cattle bile (CB) has long been used in Japan as an ingredient of digestive medicines. Bile acids are major chemical constituents of CB, and CB ingestion is assumed to affect small intestinal injury induced by nonsteroidal anti-inflammatory drugs (NSAIDs). Mice were fed a diet supplemented with or without CB for 7 days and treated with diclofenac sodium (DIF) to induce small intestinal injury. Lesion formation was enhanced, and PGE2 content and COX expression levels were elevated in the small intestine of DIF-treated mice fed the CB diet compared with those fed the control diet. The administration of a reconstituted mixture of bile acids found in CB enhanced lesion formation in DIF-treated mice. CB administration elevated the contents of CB-derived bile acids in the small intestine, some of which exhibited a high cytotoxicity to cultured intestinal epithelial cells. These results suggest that the elevated levels of CB-derived cytotoxic bile acids in the small intestine contribute to the aggravation of DIF-induced small intestinal injury. The use of CB may be limited during the therapy of inflammatory diseases with NSAIDs.

Intestinal bile acid physiology and pathophysiology

Bile acids (BAs) have a long established role in fat digestion in the intestine by acting as tensioactives, due to their amphipathic characteristics. BAs are reabsorbed very efficiently by the intestinal epithelium and recycled back to the liver via transport mechanisms that have been largely elucidated. The transport and synthesis of BAs are tightly regulated in part by specific plasma membrane receptors and nuclear receptors. In addition to their primary effect, BAs have been claimed to play a role in gastrointestinal cancer, intestinal inflammation and intestinal ionic transport. BAs are not equivalent in any of these biological activities, and structural requirements have been generally identified. In particular, some BAs may be useful for cancer chemoprevention and perhaps in inflammatory bowel disease, although further research is necessary in this field. This review covers the most recent developments in these aspects of BA intestinal biology.

Ursodeoxycholate/Sulindac combination treatment effectively prevents intestinal adenomas in a mouse model of polyposis

BACKGROUND & AIMS

Preclinical studies in animal models, human epidemiological data, and clinical trials in patients with adenomatous polyposis have consistently indicated that sulindac and other nonsteroidal antiinflammatory drugs or cyclooxygenase inhibitors have the greatest potential efficacy among current candidates for colon tumor chemopreventive agents. However, at highly effective doses they all have some risk of toxicity, and their therapeutic profile might be improved by use at lower, more tolerable doses, in combination with a second agent acting via other mechanisms.

METHODS

Sulindac was tested in combination with ursodeoxycholic acid (ursodiol), a naturally occurring 7-B-epimer of the bile component chenodeoxycholic acid, for prevention of adenomas in the Min mouse model of adenomatous polyposis.

RESULTS

Ursodeoxycholic acid caused a dose-dependent decrease in the number of intestinal tumors. Unlike sulindac and other nonsteroidal anti-inflammatory drugs, which are quite beneficial in the distal intestine but are somewhat less effective in the proximal small intestine (especially the clinically important periampullary duodenum), ursodeoxycholate had equal efficacy throughout the entire intestine, both proximal and distal. Combined treatment with low-dose sulindac was less toxic, with normal weight gain and fewer gastrointestinal ulcerations than high-dose sulindac. Combined treatment with sulindac and ursodeoxycholate was more effective than either agent alone for the prevention of tumors throughout the entire intestine.

CONCLUSIONS

These experiments provide the first evidence that ursodeoxycholic acid is effective for preventing adenomas in an animal model. Cyclooxygenase inhibition, when combined with this naturally occurring bile component, may become a promising approach for colon cancer prevention.