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 the levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the cerebral cortex and striatum without affecting the levels of 5-HT, norepinephrine and their metabolites. This action persisted for 8 hr with a maximum effect at 1-2 hr. The SM-9018-induced increase of dopamine (DA) turnover, as indexed by HVA/DA and DOPAC/DA ratios, was comparable in the cerebral cortex and striatum, whereas the typical neuroleptic haloperidol preferentially enhanced the striatal DA turnover. These findings suggest that SM-9018, unlike haloperidol, increases DA turnover to a similar extent both in the cerebral cortex and striatum.