Role of glutamine in neuronal survival and death during brain ischemia and hypoglycemia.

In this review, we discuss the role of glutamine in the nervous system as a precursor of the excitatory neuromediator glutamate, on one hand, and as an energy substrate for mitochondria in nerve and glial cells during normal and pathological processes, on the other hand. Particular attention is devoted to the functioning of the glutamine-glutamate cycle enzymes during brain ischemia and hypoglycemia and to processes of neuromediator regeneration in neurons. We thoroughly discuss the role of glutamine synthetase in mechanisms of ammonium detoxification and the role of glutamine as a possible factor in astrocyte damage. The analyzed data suggest that the constant maintenance of optimal concentrations and ratio of glutamine to glutamate in nerve tissue is not only critically important for the normal functioning of nervous system, but is also necessary for neuron and astrocyte viability.