GLT-1 mediates exercise-induced fatigue through modulation of glutamate and lactate in rats.

Glutamate has been implicated in exercise-induced fatigue, but the underlying mechanism is unknown. This study aimed to determine whether glutamate transporter-1 (GLT-1) has a key role in the regulation of exercise-induced fatigue. The expressions of GLT-1 and glial fibrillary acidic protein (GFAP) in the supplementary motor area of rats exposed to exhaustion were analyzed by immunohistochemistry. The expression of GLT-1 was further confirmed by Western blotting. The effects of GLT-1 on extracellular levels of glutamate and lactate and on exercise endurance were studied by microdialysis. GLT-1 expression was decreased in rats subjected to exercise-induced fatigue. Functional inhibition of GLT-1 using dihydrokainate and transcriptional inhibition of GLT-1 using antisense oligodeoxynucleotides led to a decrease in exercise endurance with a subsequent increase in extracellular glutamate concentration and decrease in extracellular lactate concentration. The expression of GLT-1 in the supplementary motor area is reduced after strenuous exercise, resulting in an increased extracellular glutamate concentration and decreased extracellular lactate level that may be responsible for the development of fatigue. GLT-1-mediated uptake of glutamate ameliorates exercise-induced fatigue in rat models.