Systemic apomorphine reverses intrastriatal dopamine-induced contralateral deviation.

Contralateral deviation induced by unilateral injection of 25 micrograms or 100 micrograms dopamine into the dorsal CPU was reversed to ipsilateral deviation by apomorphine administered systemically (1 mg/kg s.c.) before, at the same time, or after the dopamine. Contralateral deviation to a unilateral intrastriatal injection of 6.25 micrograms apomorphine was also reversed to ipsilateral deviation by systemically administered apomorphine. No significant effects on postural deviation were found when a control solution was injected unilaterally into the striatum, followed by systemic apomorphine. Contralateral deviation to the unilateral intrastriatal dopamine injection continued following a further bilateral intrastriatal injection of either dopamine or apomorphine. These results suggest that intrastriatal dopamine indirectly affects sites receptive to dopamine outside the striatum.