Effect of a low-dose endotoxin pretreatment on the gastric mucosal damage induced by aspirin, phenylbutazone and reserpine in rats.

The effect of endotoxin pretreatment (1 mg/kg body weight, i.p., once daily for 2 days) on the gastric mucosal damage induced by aspirin, phenylbutazone and reserpine has been studied in albino rats. When given alone, endotoxin did not produce any visibly discernible gastric lesions. It produced a significant augmentation of the gastric lesions produced by phenylbutazone and reserpine but did not significantly alter the ulcerogenicity of aspirin. The involvement of endogenous histamine formation and its release following phenylbutazone and reserpine administration and also in response to endotoxin pretreatment may be responsible for the exacerbation of gastric lesions induced by these drugs. Recent reports indicate the involvement of endorphins and platelet activating factor (PAF) in the ulcerogenic activity of endotoxin when used in high doses and their role in the potentiation of phenylbutazone- and reserpine-induced gastric lesions has to be worked out.