Unaltered cytochrome oxidase, glutamate dehydrogenase and glutaminase activities in platelets from patients with sporadic amyotrophic lateral sclerosis - A study of potential pathogenetic mechanisms in neurodegenerative diseases

Sporadic Amyotrophic Lateral Sclerosis (SALS) is a fatal neurologic disease characterized by degeneration of motor neurons in the spinal cord, brainst em and cortex. While familial cases of ALS exist, the sporadic form account s for the majority of adult-onset cases. It has been hypothesized that the neurodegenerative mechanisms underlying SALS might arise from glutamate-med iated excitotoxicity and mitochondrial dysfunction. Studies on autopsied SA LS spinal cord and brain have reported decreased cytochrome oxidase activit y, decreased astrocytic glutamate-transporter protein, and alterations of g lutamate levels and glutamate metabolizing enzyme activities. We conjecture d that if alterations in glutamate metabolism and cytochrome oxidase activi ty occur in the SALS central nervous system these alterations may also be m anifested in peripheral tissues such as platelets in living SALS patients. In this study we compared the activities of cytochrome oxidase, citrate syn thase, glutamate dehydrogenase and glutaminase in platelets from SALS and c ontrol subjects. We found that there were no differences in any of the enzy me activities measured between the two groups. Our data argue against gener alized ubiquitous biochemical alterations of these enzymes in SALS patients .