Effects of fasting and refeeding on some metabolic characteristics of rat brown adipose tissue

To investigate the effects of fasting and refeeding on rat interscapular brown adipose tissue (BAT), we determined in vitro oxygen consumption, in vitro lipolysis, DNA content and composition of fatty acid (FA). Fasting decreased the weights of body and BAT, and the DNA content of BAT. Fasting reduced both basal oxygen consumption and basal lipolysis of BAT. Fasting also suppressed the noradrenaline- and glucagon-induced increases in both oxygen consumption and lipolysis of BAT. In both triglyceride and phospholipid FA of BAT the extent of unsaturation was increased by fasting. Refeeding restored all of these parameters to the control level. These observations indicate that fasting reduces both oxygen consumption and lipolysis of BAT, resulting in reduced thermogenesis, while fasting could stimulate BAT in certain phases of its function as observed in FA composition.