Responsiveness of extracellular dopamine in the nucleus accumbens to systemic quinpirole and eticlopride is modulated by low-level lead exposure

Environmental lead exposure has been linked to learning and memory impairments as well as psychosocial deficits in children. Although the precise mechanisms by which lead exerts these effects are not completely understood, experimental animal studies suggest the involvement of mesolimbic dopamine system. Here, we investigated the effects of post weaning, 90-day exposure to 50 ppm lead on the responsiveness of extracellular dopamine in the nucleus accumbens core to quinpirole and eticlopride using in vivo microdialysis in anesthetized Long-Evans rats. Attenuation of dopamine release by 1 mg/kg quinpirole was more pronounced in lead-exposed rats compared to control rats. In contrast, eticlopride did not significantly modulate extracellular dopamine in lead-exposed rats as it did in the control group. Taken together, these results provides further evidence that exposure to environmentally relevant levels of lead disrupts mesolimbic dopamine system function, at least in part, through perturbations of D 2 receptor systems.