Pharmacological evidence for cerebral dopamine receptor blockade by metoclopramide in rodents.

Metoclopramide antagonises apomorphine-induced stereotypy in rats (ED50 1.5 mg/kg), apomorphine reversal of reserpine-induced locomotor suppression in mice (50% inhibition produced by 17 mg/kg), and apomorphine- or amphetamine-induced turning behaviour in mice with unilateral lesions of the striatal dopaminergic nerve terminals (ED505.0 and 4.0 mg/kg respectively). Metoclopramide resembles pimozide in all these respects and appears to be a relatively potent antagonist of striatal dopamine receptors. Yet metoclopramide, in anti-emetic doses, has no effect on disability in Parkinson's disease or on the therapeutic benefit of L-Dopa and L-Dopa dyskinesias.