Effect of acute and chronic lead exposure on apomorpine-induced sniffing in rats.

Sniffing is a behaviour which can be induced by dopamine D1/D2 receptor agonists. In order to test the effect of chronic lead exposure on dopamine receptor subtypes, we studied the effects of acute and chronic lead exposure on sniffing induced by apomorphine, a dopamine receptor agonist. Intraperitoneal injection of the dopaminergic receptor agonist, apomorphine (0.25-1 mg/kg), induced dose-dependent the sniffing behaviour in rats. Acute administration of lead acetate (50, 100 and 200 mg/kg) deceased the apomorphine-induced sniffing. Chronic lead (0.25%) exposure also decreased the apomophine response Dopamine D1 or D2 receptor antagonists reduced the apomorphine effect. Lead exposure could not potentiate the blockade induced by the dopamine receptor antagonists. It is concluded that the response of lead is not mediated by alteration of dopamine receptors.