Pharmacological basis of the therapeutic effect of (−)deprenyl in age‐related neurological diseases

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Abstract
(-)Deprenyl (Selegiline, Jumex, Eldepryl, Movergan), a close structural relative to phenylethylamine (PEA), is a drug of a unique pharmacological spectrum. (a) It is highly potent and selective irreversible inhibitor of B-type monoamine oxidase (MAO), a predominantly glial enzyme in the brain, the activity of which significantly increases with age. (-)Deprenyl was the first selective inhibitor of MAO-B described in literature, became the worldwide research tool used for blocking selectively B-type MAO, and is still the only MAO-B inhibitor in clinical use. (b) (-)Deprenyl interferes with the uptake of catecholamines and indirectly acting sympathomimetics because it is handled by the catecholaminergic neuron similarly to the physiological substances transported through the axonal end-organ and vesicular membrane. The unique behavior of (-)deprenyl is that, in striking contrast to PEA and its relatives, it does not push the transmitter from the storage places, i.e., it is not a releaser. The net result is that (-)deprenyl inhibits the releasing effect of tyramine and is presently the only safe MAO inhibitor which can be administered without dietary restrictions. (c) Maintenance on (-)deprenyl enhances selectively superoxide dismutase (SOD) and catalase activity in the striatum. This effect is unrelated to the MAO and uptake inhibitory effects of the drug. (d) Maintenance on (-)deprenyl facilitates the activity of the nigrostriatal dopaminergic neurons with remarkable selectivity. This effect is also unrelated to either the MAO or the uptake inhibitory effects of the drug. All in all, (-)deprenyl maintains the activity of the nigrostriatal dopaminergic machinery on a higher activity level and slows down its age-related decline. Male rats maintained on (-)deprenyl lost their capacity to ejaculate later, retained their learning ability longer, and lived longer than their saline-treated peers. Parkinsonians on levodopa plus (-)deprenyl (10 mg daily) lived significantly longer than those on levodopa alone. (-)Deprenyl is the first drug which retards the progress of Parkinson's disease. Freshly diagnosed parkinsonians maintained on (-)deprenyl did not require levodopa until significantly later than their placebo-treated peers. Maintenance on (-)deprenyl significantly improved the performance of patients with Alzheimer's disease. It is concluded that in Parkinson's disease and Alzheimer's disease patients need to be treated daily with 10 mg (-)deprenyl from diagnosis until death, irrespective of other medication.(ABSTRACT TRUNCATED AT 400 WORDS)