CNS involvement in the antisecretory action of [Met5]enkephalinamide on the rat intestine.

The effects of the stable enkephalin, [D-Ala2, Met5]enkephalinamide (DAMA) were examined on basal and stimulated fluid accumulation in intestinal loops of anesthetized Wistar-Furth rats. DAMA (0.1-3.0 micrograms, i.c.v.) dose-dependently increased basal fluid absorption in the medial ileum and decreased jejunal and proximal ileal fluid secretion after 4 h cholera toxin (1 microgram/loop) pretreatment. The antisecretory effects of DAMA were blocked by naltrexone (1 mg/kg s.c.). Thus, the antisecretory effects of opioids may be partially mediated at CNS sites.