Differential effects of the enantiomers of 3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP) at dopamine receptor sites.

The agonist actions of 3-PPP at central dopamine (DA) autoreceptors were found to reside mostly in its (+) enantiomer, (+)-3-PPP also reduced striatal content of DOPAC and HVA, whereas (-)-3-PPP elevated HVA levels. Only (-)-3-PPP antagonized DA stimulation of DA-receptor linked adenylate cyclase. It was more effective than (+)-3-PPP at inhibiting [3H]DA binding to striatal membranes. The results suggest that (+)-3-PPP may act predominantly at DA autoreceptors, while (-)-3-PPP exhibits weak affinity for presynaptic and postsynaptic DA receptors.