Metabolic features of rats resistant to a high-fat diet
S Akieda-Asai1, S Koda, M Sugiyama
1Frontier Science Research Center, University of Miyazaki, Miyazaki 889-1692, Japan.
Objective:
We assessed the metabolic characteristics of high-fat-diet-resistant (DR) rats.
Methods:
Body weight, energy intake, locomotor activity, oxygen consumption, plasma leptin and lipid levels, size of visceral-fat adipocytes, and mRNA levels of genes related to lipid metabolism were measured in control rats fed standard chow and in obesity-prone (high-fat-diet-induced obesity, DIO) and DR rats fed a high-fat diet. Glucose tolerance and insulin tolerance tests were also performed.
Results:
DIO rats gained weight more rapidly than did DR and control rats; DR rats gained less weight than did DIO rats despite similar energy intake. Energy expenditure did not differ among the three groups. The diameter of visceral-fat adipocytes was similar in DR and control rats. mRNA levels of genes involved in lipogenesis, such as fatty acid synthase and acetyl-CoA carboxylase, tended to be lower in DR than in control and DIO rats, whereas those of carnitine palmitoyltransferase 1a, which is involved in fatty acid β-oxidation, were greater in DR rats than in the other groups. DIO rats showed hyperinsulinemia and glucose intolerance, whereas DR rats had high sensitivity to insulin.
Conclusion:
DR rats show suppression of lipogenesis and acceleration of fatty acid β-oxidation in the visceral fat. These characteristics likely contribute to the anti-obesity phenotype of DR rats.
