D1/D2 dopamine receptor interaction in membrane abolished by 6-hydroxydopamine lesion

D-1/D-2 interaction in rat striatum was investigated by examining the effect of the D-2 antagonist spiperone on the binding of [H-3]SCH23390 to D-1 dopamine (DA) receptors. In the presence of endogenous DA, spiperone blocked D-2 receptors, then caused the increase of the binding of [H-3]SCH23390 in rat striatal homogenate. After the 6-hydroxydopamine (6-OHDA) lesion, the increase was not found even if in the addition of exogenous DA. The results suggest that the D-2 antagonist can modify the interaction between endogenous DA and D-1 receptors labeled with [H-3]SCH23390, while 6-OHDA lesion may change the state of D-1/D-2 interaction operating at the receptor level. (C) 1998 Elsevier Science Inc.