In-vitro and In-vivo Responsiveness of Muscle and Adipose Tissue to Insulin in Rats Rendered Obese by a High-fat Diet

Abstract

The influence of insulin on [6-l4 C] glucose metabolism was assessed in vitro and in vivo in epididymal adipose tissue and diaphragm of rats fed either a low-fat (9 per cent fat cal.) or a high-fat diet (72 per cent fat cal.). In vitro, diaphragm of fat-fed rats showed a lower glucose uptake than that of rats fed the low-fat diet, but had identical glycogen labeling and lactic acid production and a strongly reduced I4 CO2 production. Responsiveness of these pathways to insulin was unaltered by the fat content of the diet. The adipose tissue of fat-fed rats versus that of rats fed the low-fat diet showed: a higher lactic acid production and more efficient glycerogenesis and glycogenesis, all of these pathways being responsive to insulin; a lower glucose uptake and a strongly depressed fatty acid labeling, these two pathways being unresponsive to insulin. In-vivo labeling of glycogen in diaphragm in both basal and insulin-stimulated conditions was identical in the two groups of rats. In adipose tissue the amount of t4 C sequestered in the gh/ceride-glycerol moiety was the same in the two groups in basal and insulin-stimulated conditions, whereas the labeling of the fatty acid moiety and its increment with insulin were reduced by more than 99 per cent by the high-fat diet.These results show that alterations in fat content of the diet lead to differences in response to insulin that are pathway-and organspecific. DIABETES 27:114-20, February, 1978.A high-fat diet in rats causes dramatic changes in peripheral tissue glucose metabolism both in vitro and in vivo. 1 " 5 In addition, an impaired tolerance to intravenously 6 or orally 7 administered glucose and a reduced effect of exogenous 6 or endogenous 7 insulin

Effects of Supplemental D-Psicose on Glucose Tolerance and Serum Adipocytokine Levels in Rats Fed a High-Fat Diet or a Low-Fat Diet

“…Taken together, it appears that D-psicose as well as D-tagatose promotes hepatic glycogen synthesis by activating glucokinase. It is well established that feeding high-fat diets to rats results in an insulin-resistant state characterized by hyperinsulinemia and decreased glucose utilization (39,40). Storlien et al (39) have shown by in vivo insulin clamp experiments that high-fat feeding decreases (29-61%) glucose uptake into muscles, especially those with high oxidative capacity.…”

Diet Composition and Insulin Effect on Amylase to Lipase Ratio in Pancreas of Diabetic Rats

“…A final conclusion on the mechanism of insulin's effect on the exocrine pancreas will require a direct demonstration that insulin's ability to enhance the rate of glucose metab olism in the acinar cells is blunted in rats fed a high-fat diet as it has been reported for other tissues (14).…”

“…Changes in levels of these exocrine pancreas enzymes were also related to the changes in ketonemia. Since high-fat diets have been shown to impair insulin action on glucose metabolism (3,14) it was used in this study to provide insight with the question of whether insulin exerts its effect directly on the exocrine pancreas or through the enhancement of glu cose utilization in this tissue. The results show that the insulin effect on the amylase to lipase ratio is dependent on the fat content of the diet.…”

Lipid Infusion Impairs Physiologic Insulin-Mediated Capillary Recruitment and Muscle Glucose Uptake In Vivo

“…In addition, lipid infusion in humans (7,8) and in rats (9) gives rise to insulin resistance in muscle. Furthermore, genetically obese Zucker rats have elevated plasma levels of free fatty acids and show marked muscle insulin resistance (10), as do rats fed high-fat diets (11,12), although the type of fatty acid appears to be critical: oils of fish origin are protective against the effects of animal fat diets (13).…”