Gastric healing effect of melatonin against different gastroinvasive agents in cholestatic rats

Effect of sodium butyrate on gastric ulcer aggravation and hepatic injury inflicted by bile duct ligation in rats

BACKGROUND AND AIM

Cholestasis is positively associated with an increased risk of peptic ulceration. The present study investigated the aggravating effect of cholestasis on piroxicam-induced gastric ulceration. The study also evaluated the effect of sodium butyrate (SoB) on piroxicam-induced gastric ulceration in cholestatic animals and its effect on hepatic tissues and both effects were compared to ursodeoxycholic acid (UDCA) as a standard anticholestatic drug.

METHODS

Bile duct ligation was adopted for induction of cholestasis in rats. The cholestatic animals received saline, SoB (P.O, 400 mg/kg, twice daily) or UDCA (P.O, 30 mg/kg/day) for 4 days starting from the first day of surgery. On the 4th day, blood samples were collected for determination of serum hepatic markers, then gastric ulcers were induced by piroxicam administration (P.O, 50 mg/kg) and 4 h later, the stomach was isolated and gastric mucosa was collected for biochemical determinations. The ulcer indices for the investigated drugs were compared to omeprazole as a standard acid suppressive drug.

RESULTS

Piroxicam-induced ulceration was exacerbated in cholestatic rats. Gastric mucosa showed a significant elevation of MDA and TNF-α together with a significant decrease in GSH &VEGF levels. SoB treatment significantly attenuated ulcer development. The afforded protection was higher than that provided by UDCA and was not significantly different from that afforded by omeprazole. SoB significantly decreased gastric mucosal MDA and TNF-α level, whereas UDCA failed to alter these parameters. Both drugs significantly elevated GSH, VEGF and IL10 levels. Similar to UDCA, SoB showed a significant reduction in AST, ALT, GGT, ALP and bilirubin level. Histopathological examination confirmed the attenuating effect of SoB on gastric and hepatic injury.

CONCLUSIONS

Sodium butyrate effectively protected gastric and hepatic tissues against cholestasis-induced damage. Gastroprotection was mediated through antioxidant, anti-inflammatory and angiogenic activities.

Effects of vitamin C and melatonin on cysteamine-induced duodenal ulcer in a cholestatic rat model: A controlled experimental study

BACKGROUND

Superoxide dismutase (SOD) is one of the defense mechanisms against free radicals. Cysteamine is a cytotoxic agent, acting through generation of reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical, and superoxide, and may decrease defense activity of SOD against ROS and induce duodenal ulcer. Melatonin is a suicidal antioxidant that has a protective effect against ROS and cytoprotective effect through inhibition of the decrease in SOD activity.

OBJECTIVES

The primary aim of this study was to assess the effects of pretreatment with vitamin C and melatonin on cysteamine-induced duodenal ulcer. Secondary aims were to compare the ulcerogenic effect of cysteamine and the antiulcer effects of vitamin C and melatonin.

METHODS

This study was performed in male Wistar rats (200-250 g) in 3 groups of equal size (n = 24): bile duct ligation-induced cholestasis (test), sham, and control groups. In the test and sham groups, laparotomy was performed under general anesthesia and the common bile duct was identified; in sham rats, the common bile duct was left in situ, but in test rats, the common bile duct was isolated and doubly ligated to induce cholestasis. Animals in each group were also divided into 4 equal subgroups (n = 6). These subgroups were treated with vitamin C plus cysteamine, melatonin plus cysteamine, cysteamine alone, and saline, respectively. All animals were euthanized via overdose of ether anesthesia 24 hours after the last injection of cysteamine or saline, and 0.5 mL of blood was collected from the heart ventricle. The duodenum was cut open, washed with saline, fixed, and prepared for calculation of ulcer index (Szabo method) and histopathologic assessment. SOD activity was measured using a branded enzyme kit.

RESULTS

In all 3 groups, animals treated with cysteamine had significantly increased mean (SE) ulcer index (test, 4.00 [0.10] vs 1.17 [0.30]; sham, 3.83 [0.16] vs 0.50 [0.22]; control, 3.67 [0.21] vs 0 [0]) and decreased SOD activity (test, 146.41 [2.16] vs 299.83 [1.94] U/mL; sham, 154.75 [2.02] vs 303.08 [0.35] U/mL; control, 157.08 [1.67] vs 314.50 [1.14] U/mL) compared with saline-treated rats (all, P < 0.001). In the test rats, ulcer index was significantly increased and SOD activity was significantly decreased compared with the sham and control groups (both, P < 0.001). Pretreatment with vitamin C and melatonin was associated with attenuation of ulcer index and increased SOD activity compared with rats treated with cysteamine alone (P < 0.001). There were no significant differences in ulcer index or SOD activity between groups administered vitamin C or melatonin.

CONCLUSIONS

In this experimental study, pretreatment with melatonin or vitamin C in all rats produced significant attenuation of the ulcer index and enhanced SOD activity. Cysteamine-induced duodenal mucosal damage was greater in cholestatic rats compared with sham and control rats.