Roxindole, a potential antidepressant. I. Effect on the dopamine system.

Roxindole (EMD 49980, 5-hydroxy-3-[4-(4-phenyl-1,2,3,6-tetrahydropyridyl(1))-butyl(1)]-indole mesylate), a selective dopamine autoreceptor agonist and a potential antipsychotic drug, shows a clinical antidepressant efficacy. The present paper examined the neuropharmacological profile of roxindole in rats (male Wistar) and mice (male Albino Swiss) in respect of its influence on dopamine system. Used in low doses, roxindole decreased the locomotor activity, but in higher ones it did not induce a locomotor hyperactivity or stereotypy. It antagonized the amphetamine-induced hyperlocomotion, the amphetamine- or apomorphine-induced stereotypy, apomorphine climbing behaviour and reserpine-induced akinesia. The quinpirole-induced hyperlocomotion was inhibited by roxindole. When given alone, the drug in question, did not induce the catalepsy, but antagonized the catalepsy induced by haloperidol, spiperone and fluphenazine. The immobility time in the forced swimming test was reduced. Like typical antidepressants, roxindole given repeatedly (twice daily, 14 days) increased the hyperlocomotion induced by D-amphetamine. The results described above indicate that roxindole may have an antidepressant and antiparkinsonian activity and should be devoid of extrapyramidal side-effects.