Nomifensine and central monoamine neurons: histofluorescence studies.

The effect of nomifensine (NF) on the content of serotonin (5-HT) and catecholamines (CA) in discrete regions of rat brain was studied with the histofluorescence technique of Falck, NF, 20 and 40 mg/kg ip, produced, after 30 min, a depression of 5-HT content in the neurocytes of dorsal and median raphe nuclei (NDR and NMR). The blockade of dopamine receptors by spiperone did not abolish the action of NF in NDR, and inhibited the effect in NMR only in some animals. NF did not affect significantly the CA content in the striatum (caudate nucleus--putamen), hypothalamic paraventricular nucleus, and paraventricular rotundocellular nucleus. The results indicate, a direct action of NF on 5-HT neurons in the rat mesencephalon. In addition, the drug may also act indirectly on 5-HT neurons in NMR, via dopaminergic system.