Biogenic amine regulation of glucagon secretion.

Norepinephrine, dopamine and serotonin directly stimulated glucagon secretion by isolated perifused hamster islet. Propranolol blocked norepinephrine, dopamine and serotonin-stimulated glucagon release, suggesting that norepinephrine, dopamine and serotonin may modulate glucagon secretion via a beta-adrenergic mechanism. Dopamine and serotonin may exert their action directly via the beta receptor, stimulate residual adrenergic nerve terminals, or the release of other islet biogenic amines. We conclude that part of the stimulating effect of norepinephrine on glucagon release is beta adrenergically mediated and that dopamine and serotonin may affect glucagon secretion either directly or through the release of neurotransmitters that lead to glucagon release. Thus the intra-islet released dopamine and serotonin may contribute to the islets paracrine system by stimulating intra-islet adrenergic neurons.