Estrogen reduction is associated with a decline in skeletal muscle mitochondrial biogenesis. Molecular events associated with improvements in markers of mitochondrial biogenesis after resistance training and estradiol replacement are unknown. This study aimed to investigate the effects of ovariectomy, resistance training, and estradiol replacement on markers of mitochondrial biogenesis and protein expression related to oxidative capacity in the rat gastrocnemius pool. Estradiol replacement was performed using Silastic(®) capsules. During the 12-week resistance training, animals climbed a ladder with weights attached to their tails. Gene expression was analysed by RT-PCR, and protein content was determined by western blotting. Ovariectomy decreased the gene expression of the mitochondrial biogenesis markers PGC-1α (~73%), NRF-1 (~44%), and TFAM (~53%) (p<0.05) and decreased the protein expression of phosphorylated AMPK, CREB and AKT, which are related to oxidative capacity. Resistance training increased PGC-1α (~59%) and TFAM (~48%) expression compared to the Ovariectomy-Sedentary group. The combination of resistance training and estradiol replacement was superior to the ovariectomy-sedentary and ovariectomy-resistance training treatments regarding the gastrocnemius muscle. Estrogen deficiency altered the expression of genes and proteins that favour the development of a mitochondrial dysfunction phenotype, which was improved with resistance training and was partially improved by estradiol replacement.

Estrogen deficiency is directly related to central obesity and low-grade inflammation. Hormonal replacement and exercise training are both able to decrease fat accumulation and inflammation in postmenopausal women. However, the efficiency of resistance training (RT) and estrogen replacement (ER) in minimizing adiposity and inflammation in the visceral adipose tissue (VAT) of ovariectomized (OVX) rats has not yet been elucidated. In this study, Sprague-Dawley rats were divided into the following 6 groups: sham-operated sedentary (Sham-Sed), OVX-Sed, Sham-RT, OVX-RT, OVX-Sed-ER, and OVX-RT-ER groups. ER was performed by implanting silastic capsules containing 17β-estradiol. For RT, the animals were required to climb a 1.1-m vertical ladder with conical flasks containing weights attached to their tails for 12 weeks. Histological analyses were used to evaluate morphological changes. Gene expression levels were determined by quantitative real-time reverse transcriptase polymerase chain reaction, and protein concentrations were determined using Multiplex/Luminex assays. Ovariectomy increased the body mass (BM), adipocyte area, and inflammation in the VAT, the latter of which was indicated by reduced interleukin-10 (48%) and increased tumor necrosis factor (TNF)-α concentration (∼3%). RT efficiently decreased BM, adipocyte area, and inflammation in the OVX groups. The combination of RT and ER decreased BM (19%) and the TNF-α concentration (18%) and increased the gene and protein expression levels of adiponectin (173% and 18%). These results indicate that RT and the combination of RT and ER are efficient strategies for reducing the BM and improving the inflammatory status of OVX rats.