THE ROLE OF NMDA RECEPTORS IN THE SLOW NEURONAL DEGENERATION OF PARKINSONS-DISEASE

Parkinson's disease is a disorder, in which neurons of various neurona l systems degenerate. Furthermore, in such degenerating neurons, the c ytoskeleton seems to be affected. In this respect, Parkinson's disease resembles Alzheimer's disease. Since it has been shown, that elevated levels of intracellular calcium can disrupt the cytoskeleton and that the stimulation of glutamate (NMDA) receptors can cause high intracel lular concentrations of calcium, it has been suggested, that the stimu lation of glutamate receptors plays a role in the slow degeneration in Alzheimer's and Parkinson's disease. In case of the degeneration of t he dopaminergic nigrostriatal system in Parkinson's disease, neurons t hat contain calcium binding protein appear to be less vulnerable than the neurons that lack it, suggesting that calcium binding protein migh t protect these neurons from degeneration by preventing that cytosolic calcium concentrations increase excessively. And, since there is in t he nigrostriatal system a glutamatergic afferent pathway (the prefront onigral projection) and since dopaminergic nigrostriatal neurons conta in postsynaptic NMDA receptors, glutamatergic excitation may play a ro le in the degeneration of the nigrostriatal system in Parkinson's dise ase. If so, it may be possible to protect the neurodegeneration of the se dopaminergic neurons by NMDA receptor antagonists.