Effects of Corticosteroid on Muscle Fibers and Intramuscular Connective Tissues in Mice.

Abstract

Abstracts.The purpose of the current study was to clarify the effect of corticosteroid on muscle fibers and intramuscular connective tissues in mice. Fifteen male mice (C57BL/10ScSn) were randomly divided into three groups: control (C), steroid (S), and exercise with steroid (SE). We injected S+SE mice with 2 mg/kg dexamethasone sodium phosphate by a hypodermic, 6 days per week for 5 weeks. The group SE was made to run on a treadmill, at a speed of 10 m/min for 20 min/day. The exercise was conducted for 6 days per week for 5 weeks. After five weeks, the extensor digitorum longus (EDL) muscles from both legs were biopsied from all mice. We measured muscle fiber diameters and collagen fibrillar diameters in the endomysium. Muscle fiber diameters and collagen fibrillar diameters in group S decreased significantly compared with group C, and in group SE increased significantly compared with group S. We conclude that muscle fibers and collagen fibrillies are atrophied by corticosteroid causing muscle dysfunction in steroid myopathy. However, physical training can be effective in preventing muscle dysfunction in steroid myopathy.