title: Heroin increases the density and sensitivity of platelet alpha 2-adrenoceptors in human addicts.
abstract: The density of platelet alpha 2-adrenoceptors, quantified by means of the binding of [3H]clonidine, and the aggregation response induced by adrenaline, was investigated in ten heroin addicts. The number of binding sites for [3H]clonidine was significantly increased during heroin abuse. Concomitantly, there was a potentiation of the adrenaline-induced platelet aggregation, which suggested that continuous heroin use (opiate dependence) is associated with supersensitive platelet alpha 2-adrenoceptors in human addicts. Spontaneous heroin withdrawal further increased in the same addicts the density of platelet alpha 2-adrenoceptors. These results suggest that platelet alpha 2-adrenoceptors may be used as a model to study receptor mechanisms of opiate dependence and withdrawal in humans.
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000032:analysis* / Q000378:metabolism; D003000:Clonidine / Q000378:metabolism; D004837:Epinephrine; D005260:Female; D006556:Heroin Dependence / Q000097:blood*; D006801:Humans; D008297:Male; D010974:Platelet Aggregation; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*
chemical_list: D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D004837:Epinephrine