Selegiline (deprenyl) treatment and death of nigral neurons in Parkinson's disease.

We studied the effect of selegiline (deprenyl) treatment on the number of Lewy bodies and neuron counts in the substantia nigra in patients with Parkinson's disease (PD). The number of medial nigral neurons was greater and the number of Lewy bodies fewer in those PD patients who had been treated with selegiline in combination with levodopa as compared with patients who had received levodopa alone. This suggests that selegiline treatment may retard the death of nigral neurons, but alternative explanations, such as the reduction of levodopa dosage in selegiline-treated patients, are possible.