The effect of long-term treatment with deprenyl on basal and L-DOPA evoked dopamine release in vitro from the corpus striatum of aged rats

Summary In the present experiment, male rats (15–17 months) were injected with deprenyl (0.25 mg/kg) three times per week for six months. At 21–23 months of age the male rats were sacrificed, the corpus striatum removed and superfused in vitro. Basal and evoked dopamine and DOPAC levels, as obtained with either two infusions of L-DOPA (L-DOPA/L-DOPA) or L-DOPA followed by amphetamine (L-DOPA/AMPH), were measured from effluent superfusion samples and compared with values obtained from similarly aged animals treated identically with saline and from that obtained with young (2–4 months) animals. Treatment with deprenyl resulted in significantly greater basal dopamine and significantly lower basal DOPAC output compared with basal release levels from saline-treated aged rats and young animals. Responses to L-DOPA/LDOPA or L-DOPA/AMPH evoked dopamine and DOPAC release did not differ between deprenyl and saline-treated aged rats, however, both groups showed a significantly reduced response profile to these stimulations (L-DOPA/ L-DOPA or L-DOPA/AMPH) compared to that of young rats. These results indicate that the selective Type-B monoamine oxidase inhibitor, deprenyl, exerts a basic change in dopamine metabolism within the corpus striatum of aged rats resulting in an increase of endogenous dopamine and a decrease in endogenous DOPAC output.