Lead and ethanol coexposure: Implications on the dopaminergic system and associated behavioral functions

The present investigation involves ethanol's effects on the lead-induced al terations in the dopaminergic system. Ethanol, at a dose of 3 g/kg body wei ght for 8 weeks, resulted in a marked increase in the accumulation of lead in the blood and brain of animals receiving 50 mg lead/kg body weight. Leve ls of dopamine were found to decrease significantly, and were accompanied w ith increased norepinephrine levels in lead and ethanol coexposed animals. Uptake of tyrosine as well as the activities of tyrosine hydroxylase and mo noamine oxidase were seen to increase significantly in lead as well as etha nol-treated animals, and these were increased to a greater extent when anim als were administered lead and ethanol simultaneously. Dopamine receptor bi nding studies revealed a significant elevation in the number of binding sit es in lead and ethanol-coexposed animals. The altered dopaminergic function s were reflected by the neurobehavioral deficits in terms of motor incoordi nation, aggressiveness, and hyperactivity of animals exposed to lead, the e ffect being more pronounced in lead- and ethanol-coexposed animals. In brie f, results of this study suggests that ethanol potentiates lead-induced cel lular damage at the neurochemical and neurobehavioral level. (C) 2000 Elsev ier Science Inc.