Central (visceral) obesity is a key feature of the metabolic syndrome and an independent predictor of cardiovascular disease. Reux en Y gastric bypass (RnY) has been shown to offer protection against cardiovascular disease, but residual risk remains. It is also unknown whether the cardiovascular benefit is a consequence of a decrease in visceral (intra-abdominal) adipose tissue or of other factors. In this study, we compared the effects of RnY vs. removal of 90% of visceral adipose tissue (=5% body weight) by intra-abdominal lipectomy on cardiac function (echocardiography), macrovascular function (carotid artery stiffness) and microvascular function (coronary artery endothelium-dependent vasorelaxation) in a metabolic syndrome rat model (JCR:LA-cp, JCR). Cardiac output (CO) and ejection fraction (EF) were significantly decreased in JCR vs. normal (Sprague-Dawley, SD) rats (CO=50±5%, EF=45±2% of normal), and were significantly improved by both RnY and intra-abdominal lipectomy (CO=75±6%, EF=82±2% and CO=80±3%, EF=90±2% of normal, respectively). Likewise, acetylcholine-dependent coronary artery vasorelaxation was impaired in JCR rats (50±1% of normal), and was significantly improved by both RnY and intra-abdominal lipectomy (98±2% and 98±3% of normal, respectively). Carotid artery stiffness was significantly increased in JCR rats (~2 fold vs. SD), and was normalized by intra-abdominal lipectomy (to equal SD), but not by RnY (~2 fold vs. SD). Intra-abdominal lipectomy but not RnY also decreased cardiac and vascular elastin degradation in JCR rats (Lipectomy: ~50% (heart), ~75% (carotid); RnY: ~15% (heart), ~5% (carotid) vs. untreated JCR, respectively), concomitant with a decrease in matrix metalloproteinase 12 (MMP12), a major elastase, activation (~50% (heart), ~75% (carotid), ~87% (visceral fat), ~75% (circulating) vs. untreated JCR) and in 20-hydroxyeicosatetraeonic acid (20-HETE) levels (~4 (heart), ~7 (carotid), ~4 (visceral fat), ~4 (circulating) fold vs. untreated JCR). Thus, our data indicate that intra-abdominal adipose tissue itself is a source of factors that may be important negative regulators of micro- and macrovascular and cardiac function, but are not eliminated by RnY.
Fat metabolism is regulated by altered gene expression of lipogenic enzymes and regulatory factors in liver and adipose tissue but not in semimembranosus muscle of pigs during the fattening period
