Inhibition of glucose-induced insulin release by xylazine.
The effects of xylazine, a sedative that is extensively used in veterinary medicine, on glucose-stimulated insulin release have been studied using isolated perifused rat pancreatic islets. Xylazine had no effect on insulin release under basal conditions. Glucose-stimulated insulin release was inhibited in a concentration-dependent manner over the range of 10(-9)-10(-6) M. Maximum inhibition even with 10(-5) M xylazine was around 80%, which suggested that xylazine is only a partial agonist at its receptor. The inhibitory effect could be completely eliminated by yohimbine, an alpha 2-adrenergic antagonist, and was unaffected by prazosin, an alpha 1-adrenergic antagonist. That xylazine is a partial agonist was verified by the fact that when present in excess, it could stimulate insulin release which had already been inhibited to 100% by epinephrine. It is concluded that xylazine is a potent partial alpha 2-adrenergic agonist and that this mechanism is responsible, at least in part, for the hyperglycemia and insulinopenia associated with its use.
Abdel el Motal
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D000818:Animals; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D013843:Thiazines / Q000494:pharmacology*; D014991:Xylazine / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
D007328:Insulin; D011942:Receptors, Adrenergic, alpha; D013843:Thiazines; D014991:Xylazine; D015016:Yohimbine; D005947:Glucose