Dietary obesity in adult and weanling rats following removal of interscapular brown adipose tissue.

In order to investigate the role of brown adipose tissue (BAT) in diet-induced thermogenesis (DIT), a selection of palatable, energy-dense foods (Cafeteria diet) was used to increase the energy intakes of adult and weanling male rats, from some of which interscapular BAT (IBAT) had been surgically excised. Removal of IBAT had no effect upon energy intakes of the cafeteria-fed rats, nor of controls fed a pelleted stock diet. The rate of weight gain of intact controls was similar for the two diets, but adults with IBAT removed and fed with the cafeteria diet gained weight more rapidly than those fed the stock diet. Similarly, although intact weanlings did not exhibit excess weight gain when fed the cafeteria diet, removal of IBAT did result in more rapid weight gain of the cafeteria-fed weanlings relative to their stock-fed siblings. Nevertheless, total carcass energy was increased by some 20% in cafeteria-fed animals, irrespective of whether they had had IBAT removed. Thus there was no evidence of removal of IBAT having improved the efficiency of energy utilisation for growth. The failure to find evidence for altered levels of energy expenditure following removal of IBAT does not necessarily contradict the hypothesis that BAT mediates DIT, however, since, following removal of IBAT, there was hypertrophy of remaining BAT sites which may have compensated for the BAT removed.