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- Title
Effects of Dietary Restriction on the Gluconeogenesis in Liver of OLETF Rats.
- Authors
Hak-Yeon Bae; Sang-Yong Kim
- Abstract
An increase in gluconeogenesis in the liver is largely responsible for the enhanced hepatic glucose production and fasting hyperglycemia in individuals with diabetes mellitus. Dietary restriction is known to be effective in the therapy of diabetes mellitus for stabilizing glucose homeostasis and improving diabetic control, in part by enhancing sensitivity to insulin and improving pancreatic β-cell dysfunction. While much is known about the effects of starvation on the gluconeogenesis in liver, relatively little is known about the effects of dietary restriction without malnutrition. This study was performed to evaluate the response to dietary restriction on the glucose metabolism, especially expression of gluconeogenic enzymes and transcriptional factors such as PGC-1 and PPARs in liver of diabetic OLETF rats. OLETF rats(male, 24 weeks) for diabetic model and LETO rats(male, 24 weeks) for control group were used in this study. From the 24 weeks, all of these rats were received an allotment of food equal to 70 % of the food intake measures in last weeks. Body weight and blood glucose levels were investigated weekly and each mRNA expression of gluconeogenic enzymes such as PEPCK, fructose-l,6-bisphosphatase, and glucose-6-phosphatase were measured at 1, 2, 4, 8 weeks by real time PCR. In one breath, PPARs and PGC-1 mRNA expression were measured at the same times. The mRNA levels of PGC-1 in liver were increased to 29% in LETO rats after 8 weeks of dietary restriction, but there were no significant change in OLETF rats. The mRNA levels of PGC-1 in liver were not different statistically between two groups before dietary restriction, but there was a significant difference between two groups after 8 weeks of dietary restriction. The liver PPARγ mRNA expressions were not changed in LETO rats but increased to 23% in diabetic OLETF rats by dietary restriction. At 8 weeks, mRNA levels of PPARγ in OLETF rats were significantly increased more than in LETO rats. There were no change in the expression of PPARα and PPARβ during dietary restriction in both groups. The expression of gluconeogenic enzymes such as PEPCK, fructose-l,6-bisphosphatase, and glucose-6-phosphatase were progressively increased during dietary restriction in both groups. In conclusion, the liver PGC-1 mRNA expression response to dietary restriction are altered in OLETF rats compared to LETO rats. These findings suggested that altered PCG-1 expression may some roles on the fasting hyperglycemia in diabetes mellitus.
- Publication
Diabetes, 2007, Vol 56, pA713
- ISSN
0012-1797
- Publication type
Academic Journal