Influence of pregnancy on the development of various gastric lesions in rats.

The influence of pregnancy, and to some extent lactation, on various gastric lesions in rats were studied. Shay ulceration and gastric lesions induced by cold-restraint stress and ulcerogenic agents, such as acetylsalicylic acid (ASA), reserpine, or epinephrine, in rats were significantly aggravated by pregnancy (day 20 of pregnancy). Gastric hypersecretion, which was observed during pregnancy in pylorus ligation preparation, appears to contribute to the mechanism of aggravation of gastric lesions. ASA induced a marked back-diffusion of acid in pregnant rats which might resulted in the aggravation of ASA-induced gastric lesions. In contrast, histamine-induced gastric lesions were markedly inhibited according according to the progress of pregnancy but after 10 days' lactation returned to the level seen in nonpregnant rats. The histaminase inhibitor aminoguanidine strongly aggravated the histamine-induced gastric lesions in pregnant rats as compared with the non-pregnant ones.