EFFECTS OF SM-9018, A POTENTIAL ATYPICAL NEUROLEPTIC, ON THE CENTRAL MONOAMINERGIC SYSTEM IN RATS

The effects of SM-9018, a potential atypical neuroleptic, on monoamine metabolism were studied in rats. SM-9018 dose-dependently increased t he levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic a cid (HVA) in the cerebral cortex and striatum without affecting the le vels of 5-HT, norepinephrine and their metabolites. This action persis ted for 8 hr with a maximum effect at 1 - 2 hr. The SM-9018-induced in crease of dopamine (DA) turnover, as indexed by HVA/DA and DOPAC/DA ra tios, was comparable in the cerebral cort'' and striatum, whereas the typical neuroleptic haloperidol preferentially enhanced the striatal D A turnover. These findings suggest that SM-9018, unlike haloperidol, i ncreases DA turnover to a similar extent both in the cerebral cortex a nd striatum.