Energetic efficiency and brown adipose tissue uncoupling protein of obese Zucker rats fed high-carbohydrate and high-fat diets: the effects of adrenalectomy.

The influence of diet on the response of lean and obese fa/fa rats to adrenalectomy has been studied. Adrenalectomized and sham-operated rats were fed either a semi-synthetic high-carbohydrate (HC) or high-fat (HF) diet for 13 days. Energetic efficiency, calculated for measurements of energy storage and energy intake, was increased in obese rats fed both HC and HF diets and reduced close to values of lean rats after adrenalectomy.

The effects of 2-deoxy-D-glucose on brown adipose tissue of lean and obese Zucker rats.

The response of brown adipose tissue (BAT) thermogenesis, as measured by mitochondrial GDP binding, of lean and obese Zucker fa/fa rats to 2-deoxy-D-glucose (2-DOG) has been investigated. 2-DOG reduced BAT mitochondrial GDP binding of lean rats but had no effect in obese rats. Adrenalectomy increased BAT GDP binding in obese rats and restored the 2-DOG inhibitory effect.

Regulation of sympathetic activity in lean and obese Zucker (fa/fa) rats.

Norepinephrine concentration and turnover (measured by the time-dependent loss of tissue [3H]norepinephrine specific activity) were reduced in the brown adipose tissue (BAT) of obese Zucker rats but were normal in the heart. After acclimation to a 4 degrees C environment for 7 days, BAT norepinephrine turnover was increased to similar levels in lean and obese rats. After overfeeding with sucrose BAT norepinephrine turnover increased in lean rats but was unaffected in obese rats.