Prevention of stress-induced erosive gastritis by parenteral administration of arachidonic acid.

Stress-induced mucosal ulcerations are associated with a decreased synthesis of mucosal prostaglandin (PG) E2. This phenomenon is poorly understood. To investigate whether it is due to a decreased availability of the necessary substrates to the mucosa, four groups of 10 Holtzman rats were studied: group 1 received normal saline by intraperitoneal (ip) injection; group 2 also received ip normal saline, then were submitted to stress, by the cold restraint method; group 3 received a solution of arachidonic acid (AA) ip; and group 4 also received ip AA, then were submitted to stress. After sacrifice, the number of gastric ulcerations were counted and specimens of nonulcerated mucosa were assayed for PGE2 by high-performance liquid chromatography; the mean numbers of ulcers were 0, 5.8, 0.8, and 3 and the mean levels of PGE2 were 55, 41, 125, and 62 pg/mg of wet tissue for groups 1, 2, 3, and 4, respectively. It is concluded that parenteral administration of AA reduces but does not completely eliminate stress-induced gastric ulcerations and that the stressed animals synthesized half as much PGE2 as the nonstressed ones after ip administration of equal amounts of AA, suggesting that stress reduces the availability of AA to the gastric mucosa, possibly by vascular spasm.