Abstract 17599: Obesity-related Perivascular Adipose Tissue Damage is Not Reversed by Diet-induced Weight Loss
Perivascular adipose tissue (PVAT) exerts an anticontractile effect in health that is lost in obesity. A recent study reported that this obesity-induced PVAT damage was reversed within 6-months of bariatric surgery with accompanying reduction in systolic blood pressure. However, PVAT function has not previously been characterised following weight loss induced by caloric restriction, often the first line treatment for obesity. This study investigated the role of PVAT in the control of vascular function in animal models of obesity and diet-induced weight loss.
Male SD rats were fed a 45% fat diet ad libitum for 16 weeks to induce obesity, they were then split into 2 groups; obese rats maintained on the diet and weight loss rats subjected to 50% caloric restriction for a further 4 weeks. Animals that did not gain weight on the 45% fat diet were classified as obesity resistant. A control group was also provided with a 10% fat diet ad libitum for the 20-week period. The effect of PVAT on the contractility of isolated mesenteric arteries (~250 μm internal diameter) in response to norepinephrine (1x10-5 - 3x10-9 mol.l-1) was investigated by wire myography. Data were analysed by two-way ANOVA and expressed as mean ± SEM.
In control animals, the vasoconstrictor response to norepinephrine was reduced in the presence of PVAT through an endothelium-dependent mechanism (weight = 591 g, endo: P = 0.001; no endo: P = 0.52, n = 6). The PVAT anticontractile effect was abolished in obese animals (weight = 818 g, P = 0.54, n = 6) but not obesity resistant animals (weight = 649 g, P = 0.03, n = 3) indicating that the loss of anticontractile effect is a consequence of weight gain and not diet composition. However, the vasoconstrictor response to noradrenaline in the presence of PVAT remained increased in weight loss animals (weight = 620 g, P = 0.55, n = 6) suggesting that obesity-induced PVAT damage cannot be reversed by caloric restriction alone. The vasoconstrictor response was unaltered between the groups in the absence of PVAT suggesting that changes in body weight do not affect vascular smooth muscle or endothelial cells.
In summary, our data indicate that weight gain and not diet composition induces PVAT damage that cannot be reversed by diet-induced weight loss.
- © 2013 by American Heart Association, Inc.