ANDROGEN RECEPTOR ANTAGONIST SUPPRESSES EXERCISE-INDUCED HYPERTROPHY OF SKELETAL-MUSCLE

The physiological importance of the increase in androgen receptors in exercise-induced muscle hypertrophy was investigated in rats. Together with training rat gastrocnemius muscles by electrical stimulation eve ry other day for 2 weeks, male rats were administered the androgen rec eptor antagonist, oxendolone. The androgen receptor antagonist effecti vely decreased the wet mass of the prostate, an androgen target organ, and did not significantly affect body mass. The increase in muscle ma ss induced by electrical stimulation was effectively suppressed by the androgen receptor blockade. The mean degree of muscle hypertrophy in the antagonist-treated group was significantly lower than that in the control group (102.30% vs 107.41%, respectively; P = 0.006). This resu lt suggests that the androgen pathway has a significant effect in exer cise-induced muscle hypertrophy and emphasizes the importance of the i ncrease in the number of androgen receptors in exercised muscle.