title: Dopamine receptor agonistic and antagonistic effects of 3-PPP enantiomers.
abstract: The pharmacological profile of the enantiomers of the proposed selective dopamine (DA) autoreceptor agonist 3-PPP [3-(3-hydroxyphenyl)-N-n-propylpiperidine] has been studied. In vitro both enantiomers showed weak DA agonistic activity, and (--)-3-PPP some DA antagonistic effect on DA-stimulated adenylate cyclase activity. Both enantiomers in low doses had a similar profile in vivo: Inhibition of locomotor activity of mice and rats, induction of contralateral circling behaviour in 6-hydroxy-DA-lesioned rats and an emetic effect in dogs. At higher doses, differential effects of the enantiomers were found: (+)-3-PPP induced hyperactivity, weak stereotyped behaviour and ipsilateral circling in hemitransected rats. (--)-3-PPP had depressant effects in high doses, inhibited d-amphetamine-induced hyperactivity and d-amphetamine-, methylphenidate- and apomorphine-induced stereotyped licking/biting in rats and antagonized apomorphine-induced emesis in dogs. However, (+)-3-PPP also showed a weak antagonistic activity against d-amphetamine-induced hyperactivity and d-amphetamine- and apomorphine-induced stereotypy in rats and inhibited apomorphine-induced emesis in dogs. It is suggested that both enantiomers have significant effects on postsynaptic DA receptors in high doses: (--)-3-PPP with weak antagonistic activity in some test models and (+)-3-PPP with agonistic and antagonistic effect. Since these effects of (+)-3-PPP were of low intensity at high doses, (+)-3-PPP may be a partial DA agonist at postsynaptic receptors in high doses.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000932:Antiemetics; D014150:Antipsychotic Agents / Q000494:pharmacology; D002375:Catalepsy / Q000139:chemically induced; D004285:Dogs; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D011954:Receptors, Dopamine / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism; D013237:Stereoisomerism; D013239:Stereotyped Behavior / Q000187:drug effects; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D000932:Antiemetics; D014150:Antipsychotic Agents; D010880:Piperidines; D011942:Receptors, Adrenergic, alpha; D011954:Receptors, Dopamine; D012701:Serotonin; C026539:preclamol; D000262:Adenylyl Cyclases; D004298:Dopamine; D009638:Norepinephrine