No abstract

Recently, the excitatory amino acid neurotransmitter glutamate was implicated in the pathogenesis of a variety of chronic degenerative neurological diseases in humans and animals. This report describes abnormalities in excitatory amino acids in the central nervous system of 18 patients with amyotrophic lateral sclerosis (ALS). The concentration of the excitatory amino acids glutamate and aspartate in the cerebrospinal fluid were increased significantly (p less than 0.01) by 100 to 200% in patients with ALS. Similarly, the concentrations of the excitatory neuropeptide N-acetyl-aspartyl glutamate and its metabolite, N-acetyl-aspartate, were elevated twofold to threefold in the cerebrospinal fluid from the patients. There was no relationship between amino acid concentrations and duration of disease, clinical impairment, or patient age. In the ventral horns of the cervical region of the spinal cord, the level of N-acetyl-aspartyl glutamate and N-acetyl-aspartate was decreased by 60% (p less than 0.05) and 40% (p less than 0.05), respectively, in 8 patients with ALS. Choline acetyltransferase activity was also diminished by 35% in the ventral horn consistent with motor neuron loss. We conclude that excitatory amino acid metabolism is altered in patients with ALS. Based on neurodegenerative disease models, these changes may play a role in motor neuron loss in ALS.

The pathogenesis of cell death in amyotrophic lateral sclerosis (ALS) may involve glutamate-mediated excitotoxicity, oxidative damage, and apoptosis. We used a transgenic mouse model of ALS to determine the effect of inhibition of cyclooxygenase-2 in treating the disease. Cyclooxygenase-2, present in spinal neurons and astrocytes, catalyzes the synthesis of prostaglandin E2. Prostaglandin E2 stimulates glutamate release from astrocytes, whereas cyclooxygenase-2 also plays a key role in the production of proinflammatory cytokines, reactive oxygen species, and free radicals. Treatment with a selective cyclooxygenase-2 inhibitor, celecoxib, markedly inhibited production of prostaglandin E2 in the spinal cords of ALS mice. Celecoxib treatment significantly delayed the onset of weakness and weight loss and prolonged survival by 25%. Spinal cords of treated ALS mice showed significant preservation of spinal neurons and diminished astrogliosis and microglial activation. Our results suggest that cyclooxygenase-2 inhibition may benefit ALS patients.