Printed in U.S.A. SIGNIFICANCE OF DOPAMINE RECEPTOR ACTIV- ITY IN dl-p-METHOXYAMPHETAMINE- AND d-

TSENG, L.-F. AND H. H. L0H: Significance of dopamine receptor activity in dl-p-methoxyamphetamine- and d-amphetamine-induced locomotor activity. J. Pimar-macol. Exp. Ther. 189: 717-724, 1974. The effects of apomorphine, bulbocapnine and haloperidol on dl-p-methoxyamphetamine (PMA)- and d-amphetamine-induced locomotor activities were studied in mice and rats. Small doses of PMA or of apomorphine given alone did not increase the locomotor activity. When both PMA and apomorphine were injected into mice or rats, a marked increase in locomotor activity was induced. The increased locomotor activity caused by a high dose of PMA or by small doses of d-amphetamine was blocked effectively by bulbocapnine or haloperidol. PMA, even in high doses, did not induce stereotyped be-havior. d-Amphetamine, but not PMA, antagonized bulbocapnine-induced catalepsy in mice. The results are consistent with the biochemical findings that PMA is as effective as d-amphetamine in causing the release of norepinephrine from central norepinephrine-containing neurons, but is much less effective than d-amphetamine in causing the releas