Effects of riluzole on the electrophysiological activity of pallidal neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated monkey

The effect of riluzole administration, an antiglutamatergic compound, on th e electrophysiological activity of the pallidal complex of 1-methyl-4-pheny l-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys is compared with those induced by two dosages of levodopa (L-DOPA), the first affording the best c linical alleviation, the second sufficient to induce dyskinesias. Both dosa ges of L-DOPA reduced sharply the firing frequency of globus pallidus pars internalis (GPi) neurons (respectively, 43.8 +/- 23.0 and 27.4 +/- 20.2 vs. 111.2 +/- 31.4 Hz), decreased the percentage of bursting cells (respective ly, 60.7 and 50.0 vs. 80.3%) and augmented the number of regular cells (res pectively, 6.5 and 33.0 vs. 4.8%). Riluzole restored the firing frequency ( 75.0 +/- 26.9 Ht) and the firing pattern of the GPi (39.7% bursting, 9.5% r egular and 50.8% irregular). These results suggest that the emergence of dy skinesia may well be due to a modification of the neuronal messages transmi tted from the GPi to the motor nuclei of the thalamus. Riluzole would repre sent an interesting alternative to dopamine therapy in Parkinson's disease since it regularizes firing but does not cause dyskinesia. (C) 2000 Elsevie r Science Ireland Ltd. All rights reserved.