Role of striatal acetylcholine on dopamine D1 receptor agonist-induced turning behavior in 6-hydroxydopamine lesioned rats: a microdialysis-behavioral study

The effects of MK-801, a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist, of quinpirole, a dopamine (DA) D₂ receptor agonist, and of SCH 58261, an A_2A adenosine antagonist, were studied on acetylcholine (ACh) release in the striatum of 6-hydroxydopamine (60HDA) lesioned rats and on turning behavior induced by the administration of the DA D₁ agonist CY 208-243. Administration of CY 208-243 to 60HDA lesioned rats induced turning behavior and dose-dependently stimulated ACh release. At the dose of 50 μg/kg, MK-801 failed to affect basal ACh, while at 100 μg/kg MK-801 reduced it; however, MK-801 (50 and 100 μg/kg) potentiated the turning behavior elicited by CY 208-243, but failed to affect the CY 208-243-induced increase of striatal ACh release. The administration of quinpirole induced low-intensity turning behavior and decreased basal ACh release; on the other hand, quinpirole potentiated the turning behavior induced by CY 208-243, but failed to affect the CY 208-243-elicited increase of ACh release. Finally, intravenous administration of SCH 58261 stimulated basal ACh release but not turning behavior, SCH 58261, however, potentiated turning behavior induced by CY 208-243, while failing to affect the D₁-elicited increase of ACh release. These results indicate that potentiation of D₁-dependent turning behavior by MK-801, quinpirole and SCH 58261 is not mediated by a reduced ability of D₁-agonists to stimulate ACh release from the denervated striatum.