Increased capacity for fatty acid synthesis in white and brown adipose tissues from 7-day-old obese Zucker pups.

The activity of fatty acid synthetase was measured in liver, and white and brown adipose tissues of suckling lean and obese Zucker pups. In contrast to liver where no change could be observed, a significant increase in fatty acid synthetase activity was detected in both white and brown adipose tissues as early as 7 days of age. When the enzyme activity was expressed per inguinal fat pad whose weight was increased by 30 per cent in obese as compared to lean pups, a 50 per cent increase in fatty acid synthetase activity was observed. The increased activity was mediated through an increased enzyme content. Insulin levels were still identical in the two groups at 16 days of age but were significantly increased at days 17 and 18 in obese as compared to lean pups. The aetiological role of the increase in fatty acid synthetase, which is expressed in vivo, is discussed.