Further proof that (-)deprenyl fails to facilitate mesolimbic dopaminergic activity

The selective monaminooxidase (MAO)-B inhibitor (-)deprenyl facilitates the nigrostriatal dopamine (DA)-ergic system by a complex mechanism that includes inhibition of DA reuptake and increase of DA turnover. In this study, DA reuptake and DA turnover were measured in the olfactory tubercle of rats treated with 0.25 mg/kg (-)deprenyl for 28 days. There was no difference between these rats and the saline-treated group. In another series of experiments, we analysed how (-)deprenyl influences the action of some indirectly acting DA agonists, such as amphetamine (AM) and phenylethylamine (PEA). The effect on different behavioural patterns related either to the nigrostriatal (stereotyped behaviour) or the mesolimbic (rearing, locomotion) DAergic system was investigated. As expected, the PEA-induced stereotyped behaviour was tremendously potentiated by (-)deprenyl and the AM-induced stereotypy was reduced. At the same time there was no change in locomotion and rearing. The results give further biochemical and behavioural proof that (-)deprenyl enhances the function of the nigrostriatal DAergic system and leaves the mesolimbic DAergic neurons unaffected.