Changes in Expression of Monocarboxylate Transporters in the Rat Cerebral Cortex after Exercise-induced Fatigue Under Simulated High-altitude Hypoxia and its Significance

Abstract

ObjectiveTo explore the correlation between adaptation to exercise-induced fatigue and lactate transport and metabolism in the cerebral cortex under high-altitude hypoxia.MethodsA total of 63 SD rats were randomly divided into control, normal exercise, rush-entry-into-altitude, 3-day-altitude acclimatization, 1-week-altitude acclimatization, 2-week-altitude acclimatization, and monocarboxylate-transporter-inhibitor (altitude inhibitor injection) groups. Except for the control group, rats were subjected to exhaustive-load treadmill exercises under either normal pressure and normoxic conditions or low pressure and hypoxic conditions. The average time-to-exhaustion was used to determine variation trends in exercise-induced fatigue. The expression of monocarboxylate transporters (MCT)2 and MCT4 in the cerebral motor cortex was detected using western blotting and immunohistochemistry. The pathological evaluation of neuronal death in the cortex was carried out using Nissl staining, and the lactate content was also determined in rat brains.ResultsThe average time-to-exhaustion in the rush-entry-into-altitude and the altitude inhibitor injection groups were (61.00±6.55) min and (71.25±9.59) min, respectively, which was significantly lower than that in the normal exercise (124.75±9.36) min and the 2-week-altitude acclimatization groups (100.25±9.74) min (P 0.05).ConclusionThe adaptability of the body to exercise fatigue after altitude acclimatization is correlated with changes in the expression of MCT2 and MCT4 in the brain, which can be used as targets for medical intervention for exercise-induced fatigue.

Keywords

• high altitude
• hypoxia
• exercise-induced fatigue
• monocarboxylate transporters
• lactate
• cerebral cortex
• rats