Effects of an enkephalin analogue (DAMME) on pituitary and pancreatic function in sheep

The hormonal secretory effects of intravenously and intracerebroventricularly administered DAMME have been studied in the sheep. Serum prolactin and growth hormone levels were significantly elevated after i.v. injection of DAMME (14 micrograms kg-1) while a significant and considerably more prolonged increase occurred following i.c.v. administration of 20 micrograms of the analogue. The responses to i.c.v. but not to i.v. injected DAMME were attenuated by prior i.v. injection of naloxone. Administration of DAMME i.c.v. resulted in a detectable concentration in the peripheral circulation within two minutes and maximal levels at 120-150 minutes. No significant changes occurred in circulating concentrations of the pancreatic hormones investigated although there was a trend to somatostatin and pancreatic polypeptide levels being elevated after systemic injection of the analogue.