INTRASTRIATAL ANGIOTENSIN-II INDUCES TURNING BEHAVIOR IN 6-HYDROXYDOPAMINE LESIONED RATS

In rats with unilateral 6-hydroxydopamine lesions in the nigrostriatal pathway, injection of angiotensin II (2 nmol) into the unlesioned str iatum elicited dose-related tight rotations ipsilateral to the lesion. This rotation was suppressed by coadministration of the angiotensin A T(1) receptor antagonist, losartan (2 nmol), which had no significant effect when injected alone. Preadministration of the dopamine antagoni st, haloperidol (2 mg/kg i.p.) completely blocked angiotensin II-induc ed turning at doses of 0.3-3 nmol, and partially at 10 nmol. These res ults further confirm the hypothesis that Ang II is intrinsically invol ved in modulating dopamine release in the striatum, an effect which is mediated predominantly by AT(1) receptors.