[Cellular bases of neurodegenerative processes]

Neurodegenerative processes are generally characterized by the long-lasting course of neuronal death and the selectivity of the neuronal population or brain structure involved in the lesion. This is the case for Alzheimer's, Parkinson's or Huntington's diseases, or amyotrophic lateral sclerosis (ALS). The reasons for such a specificity are largely unknown as are generally the mechanisms of the diseases. One common feature of these diseases, however, is that the neuronal death is thought to involve apoptosis, at least partly. Interestingly, apoptosis in the brain would involve specific gene products similar to that identified in the nematode c. elegans, partly corresponding in mammals to ICE-related compounds and Bcl2 protein. The involvement of calcium as well as of oxydative stress mechanisms in such neuronal death is to be fully proved but putative modulation by external signals (such as those provided through trophic factors or even neurotransmitters) represents an interesting way to validate the current hypothesis of neuronal death in neurodegenerative diseases in humans.