Intraneuronal aggregate formation and cell death after viral expression of expanded polyglutamine tracts in the adult rat brain

Apoptosis in neurodegenerative disorders

Neuronal death underlies the symptoms of many human neurological disorders, including Alzheimer's, Parkinson's and Huntington's diseases, stroke, and amyotrophic lateral sclerosis. The identification of specific genetic and environmental factors responsible for these diseases has bolstered evidence for a shared pathway of neuronal death--apoptosis--involving oxidative stress, perturbed calcium homeostasis, mitochondrial dysfunction and activation of cysteine proteases called caspases. These death cascades are counteracted by survival signals, which suppress oxyradicals and stabilize calcium homeostasis and mitochondrial function. With the identification of mechanisms that either promote or prevent neuronal apoptosis come new approaches for preventing and treating neurodegenerative disorders.

Recent advances in Huntington's disease

Huntington's disease is a progressive and fatal neurological disorder caused by the expansion of a CAG trinucleotide repeat in exon 1 of the gene coding for a protein of unknown function that has been named huntingtin. The exact cause of neuronal death in Huntington's disease is unknown; however, the leading hypothesis is that of excitotoxicity and apoptosis induced by a defect in energy metabolism that may be caused by oxidative stress. How mutant huntingtin might cause these processes is unknown. New animal and cell models provide insights into the mechanism of pathogenesis and the search for the development of effective therapies.