Comparative Effects of Physical Exercise and Estradiol Therapy on Mitochondrial Density, Redox and Inflammatory Status in the Skeletal Muscle of Ovariectomized Rats

Abstract

Background Previous studies have highlighted the positive effects of estrogen replacement therapy during menopause. In addition, a growing body of evidence has also proven several beneficial effects of other therapeutic strategies, especially physical exercise, to counteract the deleterious effects of menopause on skeletal muscle. However, a comparison of the effects of exercise training versus hormone replacement therapy after menopause on muscle mitochondrial profile and redox/inflammatory status has not been investigated to date. The purpose of the study was to investigate the effects of endurance training versus estradiol therapy on mitochondrial density, redox status, and inflammatory biomarkers in the skeletal muscle of ovariectomized rats. Methods Thirty twelve weeks-old female Wistar rats were randomly assigned into three groups: Untrained ovariectomized rats (OVX-NAT); untrained ovariectomized rats with estrogen (ES) replacement (OVX-ER); and, trained ovariectomized rats (OVX-AT). After ovariectomy, The OVX-ER rats were treated with ES (subcutaneously implanted Silastic® capsule containing 360 µg of 17β-estradiol/mL) while the OVX-AT group performed a training protocol (50~70% of maximal running speed on a treadmill, 60 min/day, five days/week for eight weeks). All animals performed a maximal treadmill test before and after the training protocol. After euthanasia, the soleus muscle was processed for histological e biochemical evaluations. Results The maximal oxygen consumption (VO2max), mitochondrial muscle density, total antioxidant capacity (FRAP), catalase (CAT) activity, and interleukin 10 levels improved only in the OVX-AT group, while only the OVX-ER rats presented an increase in CAT activity and a decrease in interleukin 6 levels. Conclusions Both endurance exercise training and estradiol therapy improve redox and inflammatory balance in the skeletal muscle of ovariectomized rats; however, only exercise increases VO2max and mitochondrial muscle density.