Corticotropin-releasing factor-induced suppression of gastric emptying in the rat is blocked by cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL], an in vivo somatostatin antagonist.

Corticotropin-releasing factor (CRF) acts centrally to suppress gastric emptying and increase plasma levels of somatostatin in rats. The experiments were conducted to examine whether cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL]), which acts as a somatostatin antagonist in vivo, blocks the effect of CRF on gastric emptying of glucose. Sprague-Dawley rats were implanted with chronic intragastric fistulas and guide cannulas for fourth intracerebroventricular (4th i.c.v.) delivery. The stomach was evacuated after the offset of a 12-min intragastric glucose infusion (12.5%, 1.0 ml/min). CRF, (1000 pmol) injected 4th i.c.v. suppressed solute emptying by 44% as compared to vehicle (P < 0.001). Pretreatment with cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL]), 40 microg/kg, s.c., having no effect when delivered alone, blocked the effect of CRF on emptying. The results suggest that endogenously released somatostatin participates in CRF-induced suppression of gastric emptying during gastric fill.