DECREASED DENSITY OF I-2-IMIDAZOLINE RECEPTORS IN THE POSTMORTEM BRAINS OF HEROIN-ADDICTS

THE aim of this study was to quantitate imidazoline receptors in postm ortem brains of heroin addicts who died of an opiate overdose. The den sity of I-2-imidazoline receptors ([H-3]idazoxan binding in the presen ce of adrenaline) and the immunoreactivity of the related 29/30 kDa im idazoline receptor protein were decreased (39% and 28%, respectively) in the frontal cortex. The density of brain I-2-imidazoline receptors was also decreased in heroin-dependent rats (27%). This novel finding indicates that opiate addiction induces down-regulation of I-2-imidazo line receptors in astrocytes, and presumably down-regulation of the fu nctions associated with these receptors.