Lack of effect of intranigral administration of a dopamine analogue, (+/-)-3-(3-hydroxyphenyl)-N,n-propylpiperidine [(+/-)-3-PPP], on nigrostriatal dopamine neurones.

Bilateral injection of apomorphine into the zona reticulata of substantia nigra in rats reduced locomotor activity and striatal dopamine (DA) turnover. In contrast, bilateral injection of (+/-)-3-(3-hydroxyphenyl)-N,n-propylpiperidine [(+/-)-3-PPP] into the zona reticulata (ZR) did not reduce locomotor activity and did not affect striatal DA turnover. A high dose of (+/-)-3-PPP increased locomotor activity. Unilateral injection of (+/-)-3-PPP, but not of apomorphine, into the ZR induced a brief period of contraversive rotation. (+/-)-3-PPP may not alter nigral DA autoreceptor function but may interact with DA receptors located on non-dopaminergic nigral neurones.