Loss of regulation of lipogenesis in the Zucker diabetic (ZDF) rat.
We present here a study on the role of leptin in the regulation of lipogenesis by examining the effect of dietary macronutrient composition on lipogenesis in the leptin receptor-defective Zucker diabetic fatty rat (ZDF) and its lean litter mate (ZL). Animals were pair fed two isocaloric diets differing in their fat-to-carbohydrate ratio providing 10 and 30% energy as fat. Lipogenesis was measured in the rats using deuterated water and isotopomer analysis. From the deuterium incorporation into plasma palmitate, stearate, and oleate, we determined de novo synthesis of palmitate and synthesis of stearate by chain elongation and of oleate by desaturation. Because the macronutrient composition and the caloric density were controlled, changes in de novo lipogenesis under these dietary conditions represent adaptation to changes in the fat-to-carbohydrate ratio of the diet. De novo lipogenesis was normally suppressed in response to the high-fat diet in the ZL rat to maintain a relatively constant amount of lipids transported. The ZDF rat had a higher rate of lipogenesis, which was not suppressed by the high-fat diet. The results suggest an important hormonal role of leptin in the feedback regulation of lipogenesis.
Research and Education Institute, Harbor-University of California Los Angeles Medical Center, Torrance, California 90502, USA. Lee@GCRC.HUMC.EDU
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Lee
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Bassilian
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Lim
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Boros
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002784:Cholesterol / Q000097:blood; D003903:Deuterium / Q000032:analysis / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D002149:Energy Intake; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D019301:Oleic Acid / Q000097:blood; D010168:Palmitates / Q000097:blood; D051381:Rats; D011924:Rats, Zucker; D013228:Stearates / Q000097:blood; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007328:Insulin; D020738:Leptin; D008055:Lipids; D010168:Palmitates; D013228:Stearates; D014280:Triglycerides; D019301:Oleic Acid; D002784:Cholesterol; D003903:Deuterium