Homocysteine prevents apomorphine-induced decreases in dopamine metabolites

Low doses of apomorphine reduced dopamine (DA) metabolite concentrations in mouse and rat striata. These reductions were prevented by pretreatment with homocysteine at a dosage which had been shown to inhibit protein carboxyl and other methylation reactions in brain. By itself, homocysteine did not alter DA metabolite concentrations. These findings are discussed with regard to the possible role of cerebral methylation reactions in mediating DA autoreceptor functions.