Dietary fat-induced suppression of lipogenic enzymes in B/B rats during the development of diabetes.
This study was designed to determine the level of inhibition of gene transcription by the reduction in insulin levels upon the onset of diabetes in spontaneously diabetic B/B rats and if reducing the level of polyunsaturated fatty acids (PUFA) in the diet will increase lipogenic enzyme activity. Control (eight animals per group) and spontaneously diabetic B/B male weanling rats (25 animals per group) were fed semipurified diets containing 20% (w/w) fat of either low (0.25) or high (1.0) polyunsaturated to saturated (P/S) fatty acid ratio. Rats were killed at the onset of diabetes [blood glucose level of approximately/= 100 mg/dL (5.55 mM)] and as they became highly diabetic [blood glucose level of approximately/= 400 mg/dL (22.22 mM)]. Total RNA was extracted from liver, and the relative amount of mRNA coding for fatty acid synthase (FAS), acetyl-CoA carboxylase, malic enzyme, pyruvate kinase, and phosphoenolpyruvate carboxykinase was determined. Liver enzyme activities were also measured. The mRNA levels for FAS, acetyl-CoA carboxylase, and malic enzyme decreased compared to control animals. The mRNA level for pyruvate kinase decreased at the onset of diabetes as compared to control animals. Feeding animals the low P/S diet treatment elevated the level of mRNA and lipogenic enzyme activity compared to animals fed the high P/S diet treatment, suggesting that the effect of PUFA on lipogenic enzymes is through a direct effect on gene expression.
Cheema
S K
SK
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
Clandinin
M T
MT
D000103:Acetyl-CoA Carboxylase / Q000235:genetics; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology*; D004041:Dietary Fats / Q000494:pharmacology*; D064429:Fatty Acid Synthases / Q000235:genetics; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000235:genetics; D008297:Male; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics; D011770:Pyruvate Kinase / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011913:Rats, Inbred BB; D019014:fas Receptor / Q000235:genetics
D001786:Blood Glucose; D004041:Dietary Fats; D007328:Insulin; D008055:Lipids; D012333:RNA, Messenger; D019014:fas Receptor; D008291:Malate Dehydrogenase; D064429:Fatty Acid Synthases; D011770:Pyruvate Kinase; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D000103:Acetyl-CoA Carboxylase