The Effect of Estrogen Depletion on Skeletal Muscle Metabolism

Abstract

Skeletal muscle plays a significant role in altering metabolic activity of the body by influencing blood lipid profiles and insulin sensitivity through enzymatic processes. Hormones such as estrogen have been shown to effect skeletal muscle function. Research indicates the metabolic influence of skeletal muscle may be altered by the depletion of estrogen. Through its role in energy metabolism and expenditure, skeletal muscle likely influences the development of cardiovascular risk factors; including hypertension, diabetes, dyslipidemia, and obesity. To study the effects of estrogen depletion on skeletal muscle metabolic activity, seventeen female C57BL/6 mice have been randomly divided into two groups for the duration of 60 days; ovariectomized (OVX) and control. Circulating concentrations of total cholesterol, high–density lipoprotein, and glucose were measured prior to surgery and at 20, 40, and 60 days post-surgery. Pre- and post-trial measurements of body composition were measured on the EchoMRI. Body weight was measured weekly and food intake was calculated during a one week period. Twenty-four hour cage activity was monitored in activity chambers at 50 days. Enzymatic activity of skeletal muscle will be measured to assess oxidative capacity and rates of fatty-acid breakdown. Early results indicate that the OVX mice are gaining weight and have increased total cholesterol over baseline values. I hypothesize that estrogen-depletion will increase circulating cholesterol and glucose levels, decrease circulating high-density lipid, increase body mass and percent body fat, decrease cage activities, and decrease skeletal muscle oxidative capacity and lipid metabolism through reduced enzymatic activity.