The effect of met-enkephalin and naloxone on somatostatin and insulin secretion from the isolated, perfused rat pancreas.
The effect of met-enkephalin and the opiate antagonist, naloxone, on somatostatin and insulin secretion from the isolated, perfused rat pancreas has been studied during perfusion with 300 mg/dl glucose. In response to a gradient of met-enkephalin from 0 to 10(-5) M, release of somatostatin was inhibited at low concentrations and stimulated at high concentrations. However, both low and high concentrations of metenkephalin stimulated insulin secretion. A gradient of met-enkephalin from 0 to 10(-6) M caused only an inhibition of somatostatin release, whereas insulin release was stimulated. The effects of met-enkephalin on somatostatin release were antagonized by naloxone (10(-6) M). The metenkephalin-induced insulin secretion was partially, but not completely, blocked by naloxone. Naloxone (10(-6) M) alone changed the endocrine secretions by decreasing somatostatin release and by stimulating insulin release. Met-enkephalin may, therefore, be a physiologic regulator of pancreatic endocrine secretion.
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D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism*
D007328:Insulin; D009270:Naloxone; D013004:Somatostatin; D004744:Enkephalin, Methionine