Xylazine-induced hyperglycemia in cattle: a possible involvement of alpha 2-adrenergic receptors regulating insulin release.
The mechanism by which xylazine raises plasma glucose but lowers insulin concentrations was examined in Holstein cows. Intravenous injection of xylazine (15-150 micrograms/kg) induced a dose-dependent hyperglycemia and hypoinsulinemia for 3-4 h. An alpha 2-adrenergic blocking agent, yohimbine, and an alpha 1- and alpha 2-adrenergic blocking agent, phentolamine, at 500 micrograms/kg each reduced or abolished xylazine-induced hyperglycemia and hypoinsulinemia. The alpha 1-adrenergic blocking agents, prazosin and phenoxybenzamine, at 500 micrograms/kg each did not exert such antagonism. Prazosin at the dose studied even prolonged xylazine-induced hypoinsulinemia. The alpha-adrenergic blocking agents alone at 500 micrograms/kg each did not change either plasma glucose or insulin concentrations. The present study suggests that xylazine-induced hyperglycemia and hypoinsulinemia are mediated by alpha 2-adrenergic receptors, possibly in beta-cells of pancreatic islets which inhibit the release of insulin. The present study further suggests the use of xylazine as a pharmacological tool in the study of adrenergic influence on in vivo insulin release.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002417:Cattle; D005260:Female; D006943:Hyperglycemia / Q000139:chemically induced / Q000503:physiopathology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D013843:Thiazines / Q000494:pharmacology*; D014991:Xylazine / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
D001786:Blood Glucose; D007328:Insulin; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D013843:Thiazines; D014991:Xylazine; D015016:Yohimbine; D011224:Prazosin; D010646:Phentolamine