Neuroprotective actions of selegiline

Abstract Selegiline, a selective inhibitor of monoamine oxidase‐B (MAO‐B), was one of the first adjunct therapies in clinical neurology. A retrospective analysis of data from patients with Parkinson's disease found a significant increase in survival in those treated with selegiline plus L‐dopa compared with L‐dopa alone. The mechanism of action of selegiline is complex and cannot be explained solely by its MAO‐B inhibitory action. Pretreatment with selegiline can protect neurons against a variety of neurotoxins, such as 1‐methyl‐4‐phenyl‐1,2,3,6 tetrahydropyridine (MPTP), 6‐hydroxydopamine, N‐(2‐chloroethyl)‐N‐ethyl‐2‐bromobenzylamine (DSP‐4), methyl‐β‐acetoxyethyl‐2‐chloroethylamine (AF64A), and 5,6‐dihydroxyserotonin, which damage dopaminergic, adrenergic, cholinergic, and sertoninergic neurons, respectively. Selegiline produces an amphetamine‐like effect, enhances the release of dopamine, and blocks the reuptake of dopamine. It stimulates gene expression of L‐aromatic amino acid decarboxylase, increases striatal phenylethylamine levels, and activates dopamine receptors. Selegiline reduces the production of oxidative radicals, up‐regulates superoxide dismutase and catalase, and suppresses nonenzymatic and iron‐catalyzed autooxidation of dopamine. Selegiline compensates for loss of target‐derived trophic support, delays apoptosis in serum‐deprived cells, and blocks apoptosis‐related fall in the mitochondrial membrane potential. Most of the aforementioned properties occur independently of selegiline's efficacy to inhibit MAO‐B. © 2002 Wiley‐Liss, Inc.