THE EFFECTS OF CAPTOPRIL AND NALOXONE ON RESTRAINT - COLD-STRESS AND ETHANOL-INDUCED GASTRIC-LESIONS IN RATS

1. This study was undertaken to investigate the effect of captopril (1 mu g/kg or 1 mg/kg, IP) on the actions of naloxone (5 mg/kg, IP) in g astric ulceration induced by ethanol and restraint-cold-stress. 2. Nei ther naloxone (5 mg/kg, IP) nor captopril(1 mg/kg, IP) alone induced a ny change in the indices of the ulcer in either group. 3. Captopril at a lower dose (1 mu g/kg, IP), when combined with naloxone (5 mg/kg, I P), significantly reduced cumulative ulcer length only in the ethanol treated group (from 54.9+/-7.2 mm to 22.5+/-6.2 mm). 4. However, a hig h dose of captopril (1 mg/kg) plus naloxone pretreatment caused a sign ificant reduction in both ethanol (from 54.9+/-7.2 mm to 24.9+/-6.5 mm ) and restraint-cold-stress (from 19.0+/-3.0 mm to 5.3+/-1.0 mm)-induc ed ulcer formation. 5. Acetylsalycilic acid, when used together with c aptopril, increased the ulcer formation induced by stress. 6. Naloxone , by increasing the release of prostaglandins, has been shown to preve nt ulcer formation induced by several noxious stimuli. 7. Therefore, t he effect of the combination might be due to the synergistic interacti on of both drugs on prostaglandin synthesis. (C) 1998 Elsevier Science Inc.