(+)- and (−)-3-PPP exhibit different intrinsic activity at striatal dopamine autoreceptors controlling dopamine synthesis

Abstract

Both enantiomers of the dopamine analogue 3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP; 0.5–32 mg/kg s.c.) dose dependently reduced the increase in striatal dopamine (DA) synthesis rate produced by γ-butyrolactone (GBL). Whereas (+)-3-PPP completely prevented the action of GBL, (−)-3-PPP was only partially effective. In addition, (−)-3-PPP partially antagonised the inhibitory action of apomorphine on the GBL-induced increase in DA synthesis rate. These findings suggest that (+)- and (−)-3-PPP act as full and partial agonists respectively, at striatal DA autoreceptors controlling DA synthesis.