Intrastriatal infusion of amiloride increases rotations in 6-OHDA lesioned rats and "down-regulates" D2 receptors in the striatum and 5-HT2A receptors in the cortex.

: Intrastriatal infusion of amiloride and 12-0-tetradeconoyl phorbol-13-acetate (TPA) in 6-OHDA lesioned rats increased the apomorphine (APO)-induced rotation. This behavioral effect occurred in the presence of a decrease in the density and an increase in the affinity of D2 dopamine receptors in the striatum. There was an associated decrease in the number of 5-HT2A receptors labelled with ketanserin in the cortex on the side of infusion. These results suggest that the inositol second-messenger system may be involved in the regulation of D2-dopamine receptors in the striatum and dopamine mediated behavior in the 6-OHDA lesioned rats. They also indicate a possible role for the inositol second messenger system in the regulation of 5-HT2A receptors.