Effects of alpha 1- and alpha 2-adrenoceptor stimulation and blockade on plasma insulin levels in the mouse.
Stimulation of alpha-adrenoceptors is known to inhibit insulin secretion under a variety of conditions. In this study, the question of whether these alpha-adrenoceptors are of the alpha 1- or the alpha 2-subtype was investigated in the mouse. The selective alpha 2-adrenoceptor agonist clonidine (0.05-50 nmol/kg) was found to markedly inhibit the insulin secretory response to both glucose and the cholinergic agonist carbachol. This inhibition of insulin secretion was counteracted by the alpha 2-adrenoceptor antagonist yohimbine (2.6 mumol/kg), but not by the alpha 1-adrenoceptor antagonist prazosin (2.6 mumol/kg). In contrast, the alpha 1-adrenoceptor agonist phenylephrine (0.05-50 nmol/kg) did not affect the insulin secretory response to either glucose or carbachol. Moreover, both yohimbine and prazosin increased basal plasma insulin levels. It is concluded that alpha 1- and alpha 2-adrenoceptor blockade is followed by enhancement of basal plasma insulin levels in the mouse, whereas alpha 2-adrenoceptor stimulation but not alpha 1-adrenoceptor stimulation impairs the insulin secretory response to glucose and carbachol.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D005260:Female; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D000078790:Insulin Secretion; D051379:Mice; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011863:Radioimmunoassay; D011942:Receptors, Adrenergic, alpha / Q000145:classification / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D007328:Insulin; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D015016:Yohimbine; D002217:Carbachol; D005947:Glucose; D003000:Clonidine; D011224:Prazosin