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Department of Nutrition, Cook College, Rutgers University, New Brunswick, NJ 08903 and Department of Food and Nutrition, Iowa State University, Ames, IA 50011
Non-fa/fa and fa/fa rats were weaned at 18 days of age and fed either a high fat or high carbohydrate diet. At 6 weeks of age some of the rats fed high fat were fed the high carbohydrate diet until 10 weeks of age. Food consumption was equalized between all treatment groups. Epididymal fat pads were heavier in the fa/fa rats in all treatment groups. Fat pad weight and cellularity increased in the non-fa/fa rats fed the high fat diet. Cellularity was actually less in the fa/fa than in the non-fa/fa rats, but high fat feeding resulted in higher proportions of larger adipocytes in both phenotypes. Rates of epididymal fat pad lipogenesis and enzymatic activities were similar in both non-fa/fa and fa/fa rats in all treatment groups. Hepatic fatty acid synthesis and enzymatic activities were consistently greater in the fa/fa rats. Carbohydrate feeding resulted in increased hepatic fatty acid synthesis regardless of the earlier feeding of the fat diet, but the fa/fa rats were more responsive to the carbohydrate diet than the non-fa/fa rats. A delay in introduction of carbohydrate to the diet did not alter the eventual lipogenic capacity of fa/fa rats. Lipogenesis appeared responsive to the most recent diet.
KEY WORDS: obesity fa/fa rats lipogenesis development fat carbohydrate liver adipose tissue
1 Supported in part by National Institutes of Health grant AM 28615, grant-in-aid from the American Heart Association, New Jersey Affiliate, New Jersey Agricultural Experiment Station funds in support of N.J.A.E.S. Project No. 14116, and Iowa Agricultural and Home Economics Experiment Station funds. This article is Journal Paper No. J10808 of the Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No 2512.
2 All reprint requests should be addressed to Dr. Murray L. Kaplan, Food and Nutrition Department, Iowa State University, Ames, IA 50011.
Manuscript received 24 September 1982.