[Effect of adrenalectomy on the capacity of brown adipose tissue for thermogenesis and the development of obesity in the fa/fa Zucker rat].

This study was undertaken to examine whether adrenalectomy performed during the weaning period could correct some of the first metabolic abnormalities to develop in obese fa/fa rats: impaired thermogenesis in brown adipose tissue and hyperlipogenesis in interscapular brown and white (inguinal) adipose tissues. Pups were adrenalectomized or sham-operated at 23 days of age and studied at 30 days of age. Body weight, interscapular brown adipose tissue and inguinal white adipose tissue weight were decreased after adrenalectomy in Fa/fa and fa/fa pups. Adrenalectomy had no effect on the thermogenic capacity of brown adipose tissue (as assessed by GDP binding to mitochondria) which remained significantly lower in fa/fa than in Fa/fa rats. In both Fa/fa and fa/fa rats the lipogenic capacity of brown and white adipose tissues (as assessed by fatty acid synthetase activity) was dramatically reduced by adrenalectomy. However, in adrenalectomized rats, the fatty acid synthetase activity of brown and white adipose tissue remained 2 and 5-fold higher, respectively, in fa/fa than in Fa/fa rats. These results show that adrenalectomy at postweaning, did not affect specifically the rats bearing the fatty genotype but induced large alterations in both groups of rats. Adrenalectomized fa/fa animals remained obese as compared to the appropriate controls.