We examined the effects of a 9-week exercise training (TR) in Wistar male rats, beginning at 4 weeks of age, on the density of endothelial cells (ECs) in epididymal white adipose tissue (WAT) and the mRNA expression of angiogenic factors in adipose tissue stromal vascular fraction (SVF) cells. The number of ECs and mRNA expressions were assessed by lectin staining and real-time reverse transcriptase-polymerase chain reaction, respectively. Compared with control (CR) rats, TR rats gained weight more slowly and had significantly lower final weight of WAT due to the reduction in the size and the number of adipocytes. TR significantly increased the number of ECs per square millimeter and per adipocyte (1.37- and 1.23-fold, respectively) in WAT. This is probably because the number of adipocytes is fewer while the number of ECs is constant in the WAT of TR rats, because the regression line of TR rats for adipocyte number-dependent EC number was shifted toward the left without significant differences in the slopes between groups. TR also induced the upregulation of mRNA expression of vascular endothelial growth factor (Vegf)-A and Vegf-receptor-2 in SVF cells, thereby retaining a constant number of ECs in the WAT.
"Diminished vascular expansion in the adipose tissue may be a possible trigger of the hypoxia that ensues with obesity and may result in aponecrosis, a strong stimulus for an inflammatory response (Elias et al. 2012; Kim et al. 2012). Recent work has shown that exercise training increases endothelial cell density and VEGF gene expression in the adipose tissue of rats (Hatano et al. 2011). Additionally, HIF-1a has been shown to be increased in the stromal-vascular fraction of white adipose tissue in response to exercise training in rats (Sakurai et al. 2010 "
[Show abstract][Hide abstract] ABSTRACT: As white adipose tissue (WAT) expands under obesogenic conditions, local WAT hypoxia may contribute to the chronic low-grade inflammation observed in obesity. Aerobic exercise training is beneficial in treating WAT inflammation after obesity is established, but it remains unknown whether exercise training, while on a concomitant high-fat (HF) diet, influences WAT inflammation during the development of obesity. We sought to determine the effects of 4, 8, and 12 weeks of HF feeding and/or moderate intensity treadmill exercise training (EX) on the relationship between inflammatory and hypoxic gene expression within mouse WAT. Male C57Bl6/J mice (n = 113) were randomized into low-fat (LF)/sedentary (SED), LF/EX, HF/SED, or HF/EX groups. The low-fat and high-fat diets contained 10% and 60% energy from fat, respectively. Exercise training consisted of treadmill running 5 days/week at 12 m/min, 8% incline, 40 min/day. Quantitative real-time PCR was used to assess gene expression. HF diet impaired glucose regulation, and upregulated WAT gene expression of inflammation (IL-1β, IL-1ra, TNFα), macrophage recruitment and infiltration (F4/80 and monocyte chemoattractant protein), and M1 (CD11c) and M2 (CD206 and Arginase-1) macrophage polarization markers. Treadmill training resulted in a modest reduction of WAT macrophage and inflammatory gene expression. HF diet had little effect on hypoxia-inducible factor-1α and vascular endothelial growth factor, suggesting that WAT inflammatory gene expression may not be driven by hypoxia within the adipocytes. Treadmill training may provide protection by preventing WAT expansion and macrophage recruitment.
"Moreover, diminished vascular expansion in the adipose tissue with obesity has been suggested to be a possible trigger of the hypoxia that ensues. Interestingly, recent work has shown that exercise training increases endothelial cell density and VEGF gene expression in the adipose tissue of rats fed chow diet . We report here that exercise training also increases VEGF gene expression in HF fed young mice. "
[Show abstract][Hide abstract] ABSTRACT: We aimed to determine the effects of 6 wks of exercise on inflammatory markers in mice concomitantly fed either high-fat (HF) or normal chow (NC) diets in young mice. C57BL/6 mice were randomized into (n = 10/group) an NC/sedentary (NC/SED), NC/exercise (NC/EX), HF/SED, and HF/EX groups. Treadmill exercise was performed 5 d/wk at 12 m/min, with 12% grade for 40 min/d. Liver triglycerides and gene expression of F4/80, MCP-1, TNF-α, leptin, and VEGF in visceral white adipose were determined. NC groups had lower body weights after 6 wks versus the HF groups (22.8 ± 0.2 versus 25.7 ± 0.4 g) (P < 0.0001). F4/80 gene expression (indicator of macrophage infiltration) and liver triglycerides were greatest amongst the HF/SED group, with no differences between the remaining groups. VEGF (indicator of angiogenesis) was greatest in the HF/EX versus the other 3 groups (P < 0.05). Exposure of an HF diet in sedentary young mice increased visceral adipose depots and liver triglycerides versus an NC diet. Exercise training while on the HF diet protected against hepatic steatosis and possibly macrophage infiltration within white adipose tissue. This suggests that moderate exercise while on an HF diet can offer some level of protection early on in the development of obesity.
Mediators of Inflammation 12/2012; 2012(2):767953. DOI:10.1155/2012/767953 · 3.24 Impact Factor
"and adipose vascular function , in both the visceral depots of E rats suggested that exercise could reduce the hypoxia-related inflammation of WAT, in line with the recent demonstration that a 9-week exercise training protocol increased angiogenesis in white fat . "
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND AIM: Brown adipose tissue (BAT) plays a major role in body energy expenditure counteracting obesity and obesity-associated morbidities. BAT activity is sustained by the sympathetic nervous system (SNS). Since a massive activation of the SNS was described during physical activity, we investigated the effect of endurance running training on BAT of young rats to clarify the role of exercise training on the activity and recruitment state of brown cells. METHODS AND RESULTS: Male, 10-week-old Sprague Dawley rats were trained on a motor treadmill (approximately 60% of VO(2)max), 5 days/week, both for 1 and 6 weeks. The effect of endurance training was valuated using morphological and molecular approaches. Running training affected on the morphology, sympathetic tone and vascularization of BAT, independently of the duration of the stimulus. Functionally, the weak increase in the thermogenesis (no difference in UCP-1), the increased expression of PGC-1α and the membrane localization of MCT-1 suggest a new function of BAT. Visceral fat increased the expression of the FOXC2, 48 h after last training session and some clusters of UCP-1 paucilocular and multilocular adipocytes appeared. CONCLUSION: Exercise seemed a weakly effective stimulus for BAT thermogenesis, but surprisingly, without the supposed metabolically hypoactive effects. The observed browning of the visceral fat, by a supposed white-to-brown transdifferentiation phenomena suggested that exercise could be a new physiological stimulus to counteract obesity by an adrenergic-regulated brown recruitment of adipocytes.
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