DISUSE ATROPHY OF SKELETAL MUSCLE IN THE RAT, AGGRAVATED BY CORTISOL AND VARIOUS STRESS CONDITIONS

Abstract

Slight atrophy of the triceps surae muscle of the rat was produced by immobilization of one hind limb in a plaster of Paris cast. The development of disuse atrophy was significantly aggravated when the immobilized animal was exposed to stressors and/or treated with cortisol. These results indicate that immobilization of one limb, which did not produce any visible local damage through compression, can act as a "conditioning" factor which selectively sensitizes the muscular tissue to the catabolic effect of endogenous and exogenous corticoids. It is probable that the conditioning is due to a circulatory disturbance caused by the immobilization, but this assumption has not been definitely proved. These experiments also indicate that the type of immobilization used here can act as a "neurogenic" stressor agent, and by thus producing general catabolism predisposes the muscular tissue for the development of a greater degree of atrophy.