Effect of met-enkephalin and met-enkephalin-ARG⁶-PHE⁷ on bombesin-like immunoreactivity (BLI), somatostatin and gastrin secretion from the perfused rat stomach

In the present study we examined the effect of the two endogenous opioids met-enkephalin and met-enkephalin Arg⁶ Phe⁷ on gastric bombesin-like immunoreactivity, gastrin and somatostatin release. At doses of 10^-11, 10^-9, 10^-8 and 10^-6 M both peptides elicited a significant stimulation of bombesin-like immunoreactivity secretion, while the same doses of morphine were ineffective. The stimulatory effect was abolished by naloxone. Met-enkephalin and met-enkephalin Arg⁶ Phe⁷ stimulated somatostatin secretion at a dose of 10^-8 M, and this effect was reversible by naloxone. Neither peptide had any effect on gastrin secretion. In conclusion, the data demonstrate that both enkephalins must be considered potential regulators of bombesin-like immunoreactivity secretion in the rat stomach.