Twenty-seven pyrrolidinyl-benzamides in which substituents at 4 (R
1) and 5 (R
2) positions on benzoyl moiety and at nitrogen of pyrrolidine rings (3-pyrrolidinyl, cis-2-methylpyrrolidin-3-yl and 2-pyrrolidinylmethyl types) varied, including YM-09151-2 and sulpiride, were evaluated for their activities in inhibiting apomorphine-induced stereotypy and conditioned avoidance response and causing catalepsy in mice and rats by subcutaneous (s.c.) and intracerebroventricular (i.c.v.) administration. 1) In variation of R
1 substituents on cis-N-(1-benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxybenzamides, s.c. activities in inhibition of stereotypy and avoidance and induction of catalepsy increased in the order of CH
3NH (V) > (CH
3)
2N (VI) ≥NH
2 (IV) > H (III). After i.c.v. injection, however, the rank of potencies was CH
3NH > NH
2 ≥ (CH
3)
2N. Monomethylation of the p-amino substituent on benzoyl moiety was also found to enhance s.c. activities in other benzamides (II > I, VIII > VII, XI > X, XIV > XIII, XXIII > XXII). 2) Chlorine as R
2 substituents was more favourable than a methylsulfonyl group for intensifying anti-dopaminergic activity after s.c. administration (IV > VII, V > VIII, XIII > XV, XIX > XXI). Compounds IV and V exhibited more potent anti-dopaminergic activity than VII and VIII, respectively, both by s.c. and i.c.v. routes. In contrast, compound IX and sulpiride bearing R
2=NH
2SO
2 caused anti-dopaminergic activity only after i.c.v. injection. 3) Introduction of a benzyl group at nitrogen on the pyrrolidin ring instead of an ethyl group enhanced anti-dopaminergic activity by s.c. injection. 4) Compounds IV-VIII were more potent in inhibiting stereotypy than in inducing catalepsy after i.c.v. administration, whereas IX and sulpiride were less potent in antistereotypic activity. These results indicate that the introduction of monomethyl-amino, chlorine and benzyl groups at 4 and 5 positions on benzoyl moiety and at nitrogen of pyrrolidine ring, respectively, provides for the optimum anti-dopaminergic activity of pyrrolidinyl-benzamides. In addition, a sulfamoyl substituent is not suitable for the penetration of compounds into the brain.
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