β-glucan reduces exercise-induced stress through downregulation of c-Fos and c-Jun expression in the brains of exhausted rats

Immediate-early genes are involved in acute stress responses in the central nervous system. beta-glucan stimulates innate immune defenses, exerts an anti-tumor response and increases resistance to a wide variety of types of infection. To date, the effect of beta-glucan on the expression of immediate-early genes under stressful conditions has not been elucidated. In the present study, the effects of beta-glucan on the expression of the oncogenes c-Fos and c-Jun in the hypothalamus, dentate gyrus and dorsal raphe in rats following exhaustive treadmill running were investigated. Male Sprague Dawley rats were randomly divided into five groups (n=10 in each group) as follows: Control, exercise, exercise and 50 mg/kg beta-glucan treatment, exercise and 100 mg/kg beta-glucan treatment, and exercise and 200 mg/kg beta-glucan treatment. Rats in the beta-glucan-treated groups were administered beta-glucan at the respective dose once per day for seven days. Rats in the exercise groups performed treadmill running once per day for six days. On the seventh day of the experiment, the time to exhaustion in response to treadmill running was determined for the exercise groups. The expression of c-Fos and c-Jun in the hypothalamus, dorsal raphe and hippocampus was enhanced by exhaustive treadmill running. Administration of beta-glucan resulted in an increase in the time to exhaustion and the suppression of the exercise-induced increment in c-Fos and c-Jun expression. In conclusion, beta-glucan may exert an alleviating effect on exercise-induced stress through the suppression of c-Fos and c-Jun expression in the brains of exhausted rats.