Abstract 480: Exacerbation of Arterial Stiffness in Obese Adiponectin Deficient Mice

Abstract

Background and Objective: Arterial stiffness is recognized as being an independent predictor of incipient vascular disease associated with obesity and metabolic syndrome. In obese subjects, the decrease in the plasma level of adiponectin, an anti-diabetic and anti-atherogenic adipokine, is well known. Hence the aim of our study was to examine the effect of loss of adiponectin on the development of arterial stiffness in response to a high fat diet. Methods and Results: Male 8-week old adiponectin knockout (APN KO) and C57BL/6 (control) mice were fed a high fat diet (60% Calories from fat) for 12 weeks to induce obesity and insulin resistance (n=10/group). APN KO and C57BL/6 mice were fed a low fat diet (10% Calories from fat) and used as lean controls (n=10/group). After 12 weeks on the high fat diet, the APN KO mice weighed significantly more than the C57BL/6 mice (45.1±1.3 g vs 40.1±1.1 g, p=0.0008) but there was no difference in the final weights between genotypes fed the low fat diet. APN KO mice on both high and low fat diets for 12 weeks developed insulin resistance as measured by oral glucose tolerance test (Area under curve (AUC) mmol/L х min = 437±70 and 438±57) as compared to the C57BL/6 mice fed low or high fat diets (AUC mmol/L х min = 251±27 and 245±43). Arterial stiffness was determined by Doppler pulse wave velocity analysis of the femoral artery. Pulse wave velocity was increased in APN KO mice fed a high fat diet relative to those fed the low fat diet (12.56±0.78 cm/s vs 9.47±0.95 cm/s, p=0.0035; n=8-10). Pulse wave velocity was not different between C57BL/6 control mice on the low or high fat diets (10.63±0.73 cm/s and 10.86±0.50 cm/s), thus revealing that only mice deficient in adiponectin developed arterial stiffness in response to high fat diet. Conclusions: Potentiation of the vascular stiffness in diet-induced obese APN KO mice indicates that adiponectin has a role in modulating vascular structure and the APN KO mouse models the vascular changes that occur in human obesity and metabolic disorders. Morphometric analysis of the aortic tissues for vessel thickness and expression of extracellular proteins will further validate the potential role of adiponectin on the maintenance of arterial elasticity in addition to its known effect on eNOS mediated vasoprotection.