Lead neurotoxicity: a role for dopamine receptors

Chronic lead exposure differentially affects dopamine receptor subtypes (D1 and D2). In particular dopamine D2 recognition sites in striatum are up-regulated while in nucleus accumbens they are down-regulated. These changes may be correlated to the observed alterations of dopamine terminal activity. Consistent with these biochemical changes behavioral studies indicate that lead-treated rats show more pronounced basal activity, attenuation of apomorphine (63 micrograms/kg s.c.) induced hypomotility and tendency to increased stereotyped response to apomorphine (300 micrograms/kg s.c.). On the contrary, both behavioral and biochemical markers of D1 receptors are unmodified by lead treatment. In fact, SKF 38393-induced grooming behavior, [3H]SCH 23390 binding and the dopamine stimulated adenylate cyclase activity are comparable in controls and lead-exposed rats.