Abstract
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.