Mechanism underlying anti-apoptotic activity of a (-)deprenyl-related propargylamine, rasagiline.

A potent inhibitor of type B monoamine oxidase, (-)deprenyl, is known to protect or rescue dying neurons, independent of inhibition of the enzyme activity. After long term administration to rodents, a propargylamine structurally related to (-)deprenyl, (R)(+)-N-propargyl-1-aminoindan (rasagiline) increased the activities of anti-oxidative enzymes, superoxide dismutase and catalase. Rasagiline protected in vitro dopamine cells from apoptosis induced by oxidative stress or neurotoxins. The mechanism of the anti-apoptotic effect was studied by in vitro experiments using human dopaminergic neuroblastoma, SH-SY5Y cells. Peroxynitrite-generating N-morpholino sydonimine (SIN-1) induced apoptosis in SH-SY5Y cells via disruption of mitochondrial membrane potential (DeltaPsim), followed by caspase 3 activation. Rasagiline prevented the loss of DeltaPsim, the initial step to apoptosis, and also following caspase 3-activation and DNA fragmentation. The results suggest that rasagiline may interact with the specific molecule in the mitochondria and suppress the death signal transduction. By the anti-apoptotic function, rasagiline may rescue or protect declining neurons in aging and neurodegenerative disorders, such as Parkinson's disease.