Comparison among the lipogenic potential of various substrates in rat hepatocytes: the differential effects of fructose-containing diets on hepatic lipogenesis |
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Authors: | A Carmona R A Freedland |
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Institution: | Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616. |
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Abstract: | Fructose feeding has been reported to cause hypertriglyceridemia in rats. Apparently this is due to increased hepatic fatty acid synthesis. In hepatocytes from female rats fed a 60% sucrose or fructose diet, the rate of lipogenesis was two times higher than in cells from rats fed a 60% glucose diet and three times higher than in cells from rats fed a commercial nonpurified diet. In hepatocytes from rats fed the fructose-containing diets, lactate was a better substrate than either butyrate or acetate, whereas in cells from rats fed either the glucose diet or the non-purified diet, butyrate was the best lipogenic substrate, and the lipogenic potential of lactate and acetate was similar. In all cases, 1 mM fructose caused a 30-40% stimulation of lipogenesis, while 10 mM glucose did not enhance fat synthesis above the endogenous rates. These results suggest that the differential effect of fructose-containing diets on hepatic lipogenesis results from activation of pyruvate dehydrogenase, thereby increasing the efficiency by which lactate is used as a carbon source for fatty acid synthesis. The differences in lipogenic potential of the various substrates tested is discussed. |
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