Aorta Of Obese Rats Research Articles

The Effect of Black Garlic (Allium sativum Linn) on Cardiac and Aortic Histopathology in Experimental Studies in Obesity Rats

ABSTRACTBackground: Obesity is a disorder or disease characterized by the accumulation of excess fat in the body due to an imbalance in energy intake that is used for a long time. Accumulation of fat can reduce adiponectin, causing cardiac hypertrophy, endothelial vasodilation, and other cardiovascular diseases. Black garlic have high antioxidants in the form of S-Allylcysteine(SAC) which functions to increase adiponectin. Objective: To determine the effect of Black garlic on the histopathological picture of the heart and aorta of obese rats. Methods: This study was an experimental study with a randomized post-test only design with control group design with 5 groups of male white rats Sprague Dawley (Rattus novergicus) fed High Fat Fructose. Diet (HFFD) enriched with 1.25% cholesterol and 0.5% cholic acid for 8 weeks and was given black garlic intervention at doses of 450 mg / 200BW, 900mg / 200BW and 1350mg200 / BW for 4 weeks. Results: Giving black garlic significantly reduced body weight of rats (p = 0.001), and the results did not significantly reduce heart weight (p = 0.147), aortic weight (p = 0.061), histopathological changes in heart wall thickness (p = 0.423) and aortic wall thickness (p = 0.802). The effective doses of black garlic in this study were 450 mg / 200 grams BW, 900 mg / 200 grams rat BW and 1350 mg / 200 grams BW of rats. The optimal dose is 900 mg / 200 grams BW. Conclusion: Black garlic gave a significant reduction in body weight of rats and no significant reduction in heart weight, aortic weight, cardiac and aortic histopathological features.

Effects of carotid baroreceptor stimulation on aortic remodeling in obese rats

Background and aimOur previous study found carotid baroreceptor stimulation (CBS) reduces body weight and white adipose tissue (WAT) weight, restores abnormal secretion of adipocytokines and inflammation factors, decreases systolic blood pressure (SBP) by inhibiting activation of sympathetic nervous system (SNS) and renin-angiotensin system (RAS) in obese rats. In this study, we explore effects of CBS on aortic remodeling in obese rats. Methods and resultsRats were fed high-fat diet (HFD) for 16 weeks to induce obesity and underwent either CBS device implantation and stimulation or sham operation at 8 weeks. BP and body weight were measured weekly. RAS activity of WAT, histological, biochemical and functional profiles of aortas were detected after 16 weeks. CBS effectively decreased BP in obese rats, downregulated mRNA expression of angiotensinogen (AGT) and renin in WAT, concentrations of AGT, renin, angiotensin II (Ang II), protein levels of Ang II receptor 1 (AT1R) and Ang II receptor 2 (AT2R) in WAT were declined. CBS inhibited reactive oxygen species (ROS) generation, inflammatory response and endoplasmic reticulum (ER) stress in aortas of obese rats, restrained vascular wall thickening and vascular smooth muscle cells (VSMCs) phenotypic switching, increased nitric oxide (NO) synthesis, promoted endothelium-dependent vasodilatation by decreasing protein expression of AT1R and leptin receptor (LepR), increasing protein expression of adiponectin receptor 1 (AdipoR1) in aortic VSMCs. ConclusionCBS reduced BP and reversed aortic remodeling in obese rats, the underlying mechanism might be related to the suppressed SNS activity, restored adipocytokine secretion and restrained RAS activity of WAT.

Abstract 495: Nicotine Promotes Endothelial Dysfunction and Vascular Inflammation in Diet-induced Obese Rats: Role of Macrophage TNFa

Obesity and cigarette smoke are major cardiovascular (CV) risk factors and, when coexisting in the same individuals, have additive/synergistic effects upon CVD. We studied the mechanisms involved in nicotine enhancement of CVD in Sprague Dawley rats with diet-induced obesity . The rats were fed either a high fat (HFD) or normal rat chow (NFD) diet with or without nicotine (100 mg/L in drinking water) for 20 weeks. HFD rats developed central obesity, increased systolic blood pressure (SBP 146 ± 3 vs. 130 ± 5 mmHg in NFD , p<0.05), aortic superoxide (O 2 - 1357 ± 142 vs. 847 ± 102 counts/min/mg in NFD, p<0.05) production, and impaired endothelial nitric oxide synthase (eNOS) and endothelium-dependent relaxation to acetylcholine (EDR, Emax: 85 ± 5 vs. 99 ± 1% in NFD, p<0.05). Nicotine further increased SBP (159 ± 5 mmHg, p<0.05), O 2 - (1689 ± 87 counts/min/mg, p<0.05) and impaired eNOS and EDR (Emax: 72 ± 4%, p<0.05) in obese rats. In the peritoneal macrophages from obese rats, tumor necrosis factor (TNF) α, interleukin 1β and CD36 were increased, and were further increased in nicotine-treated obese rats. Using PCR array we found that 3 of 84 target proinflammatory genes were increased by 2-4 fold in the aorta of obese rats, 11 of the target genes were further increased in nicotine-treated obese rats. HUVECs, incubated with conditioned medium from the peritoneal macrophages of nicotine treated-obese rats, exhibited reduced eNOS and increased NADPH oxidase subunits gp91phox and p22phox expression. Those effects were partially prevented by adding anti-TNFα antibody to the conditioned medium. Our results suggest that nicotine aggravates the CV effects of diet–induced obesity including the oxidative stress, vascular inflammation and endothelial dysfunction. The underlying mechanisms may involve in targeting endothelium by enhancement of macrophage-derived TNFα.

Oral nicotine aggravates endothelial dysfunction and vascular inflammation in diet-induced obese rats: Role of macrophage TNFα.

Obesity and cigarette smoke are major cardiovascular (CV) risk factors and, when coexisting in the same individuals, have additive/synergistic effects upon CVD. We studied the mechanisms involved in nicotine enhancement of CVD in Sprague Dawley rats with diet–induced obesity. The rats were fed either a high fat (HFD) or normal rat chow diet with or without nicotine (100 mg/L in drinking water) for 20 weeks. HFD rats developed central obesity, increased systolic blood pressure (SBP), aortic superoxide (O2-) production, and impaired endothelial nitric oxide synthase (eNOS) and endothelium-dependent relaxation to acetylcholine (EDR). Nicotine further increased SBP, O2- and impaired eNOS and EDR in obese rats. In the peritoneal macrophages from obese rats, tumor necrosis factor (TNF) α, interleukin 1β and CD36 were increased, and were further increased in nicotine-treated obese rats. Using PCR array we found that 3 of 84 target proinflammatory genes were increased by 2–4 fold in the aorta of obese rats, 11 of the target genes were further increased in nicotine-treated obese rats. HUVECs, incubated with conditioned medium from the peritoneal macrophages of nicotine treated-obese rats, exhibited reduced eNOS and increased NADPH oxidase subunits gp91phox and p22phox expression. Those effects were partially prevented by adding anti-TNFα antibody to the conditioned medium. Our results suggest that nicotine aggravates the CV effects of diet–induced obesity including the oxidative stress, vascular inflammation and endothelial dysfunction. The underlying mechanisms may involve in targeting endothelium by enhancement of macrophage-derived TNFα.

Downregulation of Kir6.1/SUR2B channels in the obese rat aorta

Objective This study was designed to evaluate the contribution of adenosine triphosphate–dependent potassium channels to the increase in blood pressure observed in obese rats. Methods The experiment was performed in male Sprague-Dawley rats. Glibenclamide-sensitive currents were measured in vascular smooth muscle cells by patch-clamp. Expressions of Kir6.1 and SUR2B were examined by reverse transcription polymerase chain reaction and western blot techniques, respectively. Results In the aortic vascular smooth muscle cells, pinacidil induced glibenclamide-sensitive currents. The current from obese rats was significantly lower (−10.55 ± 1.63 pA/pF) compared with that from the control rats (−20.18 ± 2.79 pA/pF). Expressions of Kir6.1 and SUR2B were downregulated in vascular smooth muscle cells of aortas from the obese rats. Conclusion These findings suggest that the adenosine triphosphate–dependent potassium channel is downregulated in smooth muscle cells from the aortas of obese rats, which may contribute to the increase in blood pressure in these rats.

Defective insulin and acetylcholine induction of endothelial cell-nitric oxide synthase through insulin receptor substrate/Akt signaling pathway in aorta of obese rats.

The actions of acetylcholine (ACh) on endothelium mainly are mediated through muscarinic receptors, which are members of the G protein-coupled receptor family. In the present study, we show that ACh induces rapid tyrosine phosphorylation and activation of Janus kinase 2 (JAK2) in rat aorta. Upon JAK2 activation, tyrosine phosphorylation of insulin receptor substrate (IRS)-1 is detected. In addition, ACh induces JAK2/IRS-1 and IRS-1/phosphatidylinositol (PI) 3-kinase associations, downstream activation of Akt/protein kinase B, endothelial cell-nitric oxide synthase (eNOS), and extracellular signal-regulated kinase (ERK)-1/2. The pharmacological blockade of JAK2 or PI 3-kinase reduced ACh-stimulated eNOS phosphorylation, NOS activity, and aorta relaxation. These data indicate a new signal transduction pathway for IRS-1/PI 3-kinase/Akt/eNOS activation and ERK1/2 by means of JAK2 tyrosine phosphorylation stimulated by ACh in vessels. Moreover, we demonstrate that in aorta of obese rats (high-fat diet), there is an impairment in the insulin- and ACh-stimulated IRS-1/PI 3-kinase pathway, leading to reduced activation with lower protein levels of eNOS associated with a hyperactivated ERK/mitogen-activated protein kinase pathway. These results suggest that in aorta of obese rats, there not only is insulin resistance but also ACh resistance, probably mediated by a common signaling pathway that controls the activity and the protein levels of eNOS.

Altered insulin-mediated and insulin-like growth factor-1-mediated vasorelaxation in aortas of obese Zucker rats

Insulin and insulin-like growth factor-1 (IGF-1) have vasorelaxant effects in vivo, which is dependent on nitric oxide (NO) production. The aim of this study was to investigate the vasorelaxant responses mediated by insulin and/or IGF-1 in aortas of obese Zucker rats. The thoracic aortas of eight lean and eight obese Zucker rats (6 months old) were isolated for vasorelaxation analysis. Insulin-induced and IGF-1-induced vasorelaxant responses were evaluated by the isometric tension of aortic rings in the organ bathes. The roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS) in vasorelaxant responses were examined by treating selective inhibitors, such as wortmannin (an inhibitor of PI3K) and N (omega)-nitro-L-arginine methyl ester (L-NAME, a NOS inhibitor). In addition, the vascular responses to sodium nitroprusside (SNP), a direct vasodilator of vascular smooth muscle, were examined. The insulin-induced vasorelaxation in aortas of obese rats was significantly decreased, whereas the IGF-1-induced vasorelaxation was significantly increased, compared with that in lean rats. After the pre-administration of wortmannin or L-NAME, the altered insulin-induced or IGF-1-induced vasorelaxation was abolished. There was no significant difference in the SNP-induced vasorelaxation between lean and obese rats. Our findings suggested that the decreased insulin-mediated vasorelaxation in obese rats appeared to be counteracted by the increased IGF-1-mediated vasorelaxation. Furthermore, the NO-dependent pathway was involved in the altered vasorelaxant responses. However, the SNP-induced vasorelaxation was not changed in obese rats.