Different mechanisms are involved in neuropeptide Y-induced pancreatic vasoconstriction and inhibition of insulin secretion.
We have studied the mechanisms whereby neuropeptide Y (NPY) inhibits insulin secretion and induces vasoconstriction in the isolated perfused rat pancreas. Neither prazosin (alpha 1-adrenoceptor antagonist; 6 microM) nor yohimbine (alpha 2-adrenoceptor antagonist; 0.6 microM) affected the effects of neuropeptide Y (1 nM). Also the Ca2+ channel antagonist, verapamil (5 microM), which itself decreased insulin output by 55%, could not affect the neuropeptide Y-induced inhibition of insulin secretion. However, verapamil impaired the neuropeptide Y-induced decrease in pancreatic outflow rate. Finally, neuropeptide Y (1 and 10 nM) suppressed the insulin secretion induced by dibutyryl cAMP (100 microM) and the cyclic nucleotide suppressed the neuropeptide Y-induced vasoconstriction. We conclude that the secretory and vascular effects of neuropeptide Y are mediated by different processes in the perfused rat pancreas: inhibition of insulin secretion seems mediated by a mechanism distal to and/or different from cAMP generation, whereas vasoconstriction seems to involve uptake of extracellular Ca2+ and to be sensitive to dibutyryl cAMP. Both effects occur independently of adrenoceptor receptors.
Skoglund
G
G
Faculté de Médecine, URA 599 du CNRS, Montpellier, France.
Gross
R
R
Ahrén
B
B
Loubatières-Mariani
M M
MM
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D009478:Neuropeptide Y / Q000494:pharmacology*; D010179:Pancreas / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D007328:Insulin; D009478:Neuropeptide Y; D003994:Bucladesine; D014700:Verapamil