Objective: 

The aim of this study was to investigate whether estrogen can prevent eccentric exercise induced muscle damage in skeletal muscle in rat.

Methods: 

Male rats (n=36) were divided equally as estrogen supplemented (n=18) and non supplemented groups (n=18), then these groups were further divided as rest (n=6) and groups exposed to eccentric exercise (n=12). Eccentric exercise groups were further divided as rats killed after 1 h (n=6) and 48 h (n=6) of eccentric exercise. Estrogen (17-b Estradiol, 10 mg/kg per day) was administered subcutaneously for 30 days. Eccentric exercise was applied as treadmill run (15o downhill, 20 m/min) consisting of periods of 5 min run and 2 min rest repeated 18 times. Leukocyte infiltration in soleus muscle was examined histologically. Activities of glutathione S-transferase, glutathione peroxidase, superoxide dismutase and catalase were also measured spectrophotometrically.

Results: 

Estrogen alone decreased the glutathione peroxidase activity in soleus muscle compared with the control group. However, when estrogen was combined with eccentric exercise, glutathione peroxidase activity was increased. The increase in oxygen consumption during exercise and consequently increased formation of reactive oxygen species could have caused a compensatory increase in glutathione peroxidase activity, which might have been improved by estrogen. Eccentric exercise increased neutrophil infiltration in skeletal muscle suggesting the presence of the muscle damage. Leukocyte infiltration in skeletal muscle has significantly increased two fold after 48 h compared with the numbers after 1 h, and estrogen supplementation was not able to prevent this infiltration.

Conclusions: 

Estrogen seemed to be not very effective to prevent eccentric exercise-induced skeletal muscle damage. Supported by Ataturk University Research Fund (2005/192).