Capsaicin-sensitive vagal afferent fibers do not contribute to histamine H2 receptor agonist-induced gastric acid secretion in anesthetized rats.

The effect of perivagal capsaicin treatment on gastric acid secretion induced by the histamine H2 receptor agonist, dimaprit dihydrochloride, and the effect of the histamine H1 receptor agonist, 2-thiazolylethylamine dihydrochloride, on gastric acid secretion were studied in acute gastric fistula rats anesthetized with urethane. The integrated secretory response for the 2 h following subcutaneous (s.c.) administration of dimaprit dihydrochloride (5-20 mg/kg) did not differ in capsaicin- compared to vehicle-treated rats. Administration of 2-thiazolylethylamine dihydrochloride (20 mg/kg s.c.) did not modify gastric acid secretion in untreated rats. The present study demonstrates that the previously reported reduction in the secretory response to histamine by perivagal capsaicin treatment is unrelated to histamine H1 or H2 receptor.