Effect of (+-)-propranolol and clonidine on stress- and chemically induced gastric ulcers in rats.

The influence of (+-)-propranolol and clonidine on stress- and various chemically induced gastric ulcers in rats, together with their influence on various biochemical parameters which affect the development of the induced ulcers, was examined. Pretreatment of rats with (+-)-propranolol (10-100 mg/kg) and with clonidine (0.03-0.3 mg/kg) given orally, significantly reduced indomethacin- (30 mg/kg, orally) and reserpine- (5 mg/kg, i.p.) induced ulcers. In addition, propranolol pretreatment significantly reduced ethanol- and cold-stress-induced ulcers, whereas pretreatment with orally given clonidine significantly enhanced these ulcers. Pretreatment with propranolol significantly increased gastric mucus synthesis and the nonprotein sulfhydryl content and reduced gastric lipid peroxidation without affecting gastric acid secretion. Pretreatment of the animals with clonidine significantly increased gastric mucus secretion and decreased total gastric acidity. It did not affect the gastric nonprotein sulfhydryl content and lipid peroxidation. The drug-induced effects on the experimentally induced ulcers may be related to their induced biochemical alteration in the gastric parameters measured.