"" Fat Rats Lift Weights ""
Obese rat performing a "squat"
The Influence of Resistance Exercise on Metabolism in the Obese Zucker Rat
Investigators:
The purpose of this experiment is to elucidate the impairments in basal muscle metabolism in the obese Zucker rat (fa/fa), a widely used model to study the effects of obesity and insulin resistance, and to determine the efficacy of in vivo resistance training in improving insulin sensitivity/glucose uptake and lipid oxidation in these animals. Previous studies have suggested that endurance exercise may reduce cholesterol levels and increase glucose uptake in the obese Zucker rat, but the efficacy of resistance exercise to produce such responses and the mechanism for these responses are unknown. Theoretically, benefits such as improved insulin sensitivity following exercise and increased substrate oxidation may lead to increased transcription and translation of oxidative enzymes and mitochondrial proliferation. It is not known by what mechanisms (if any) resistance exercise enhances fat metabolism in insulin resistant muscle. This response has previously been seen by activating the peroxisome-proliferator activated receptor (PPAR) family of proteins which are responsible for regulation of transcription of many oxidative proteins. As such, the goal of this study is two-fold: 1) To elucidate the difference(s) in basal substrate metabolism (protein, carbohydrate and fat) in the skeletal muscle of genetically obese Zucker rats compared to lean littermates [Fa/fa or FA/FA], and 2) To determine whether or not resistance exercise can normalize global substrate metabolism in the face of insulin resistance. These studies will have important implications toward our understanding of obesity-associated diabetes and the potential therapeutic use of resistance exercise for obesity/metabolic control.