The role of nitric oxide in Parkinson's disease

Neurodegenerative disorders are adult-onset disabling neurologic conditions such as Parkinson's disease (PD) in which specific subsets of brain neurons are dying. Without exception, the frequency of these disorders is increasing dramatically as the proportion of elderly in our society grows. The search for efficacious therapies, if not to prevent, at least to slow down or halt the progression of these diseases, is of major public health importance. However, this goal can only be achieved through a better understanding of the causes and mechanisms by which neurons die in these degenerative disorders. We review here the question of nitric oxide (NO), a small and ubiquitous molecule believed to be a pivotal element in the cascade of deleterious events underlying neurodegeneration in PD. Since NO synthases (NOS) are the only known enzymes that produce NO, in this chapter particular attention is paid to the anatomic distribution and catalytic activity of these enzymes in the brain. We also provide several experimental protocols commonly used for quantitative and qualitative studies of NOS.