Effects of exercise training on adipogenesis of stromal‐vascular fraction cells in rat epididymal white adipose tissue

Abstract

These results suggest that exercise training suppresses the ability of SVF cells to differentiate into adipocytes, and that underlying mechanisms involve the upregulation of HIF-1α expression.

Preventive and improvement effects of exercise training and supplement intake in white adipose tissues on obesity and lifestyle-related diseases

“…The difference in the starting age for TR appears to influence the effects of TR on adipocyte numbers, because when TR was started at a very early stage of a rat's life (0.7-1.1 weeks of age), it reduced both adipocyte number and size; however, when TR was started at 9-27 weeks of age, only adipocyte size was reduced [21][22][23][24]. In fact, in our study, the starting age of the rats (5 weeks old), corresponding to childhood, was thought to be important for the reduction of adipocyte numbers by TR [26]. Nevertheless, additional research is necessary, because reports state that, even when TR is started at 5 weeks of age, it does not affect adipocyte number [25].…”

“…However, the results of the effects of TR on the number of adipocytes contained in WAT are controversial. Some studies, including ours, have shown that WAT in exercise-trained rodents contains significantly fewer cells than that in sedentary controls [21,22,26] or tends to do so [20], but some have found no significant difference in adipocyte numbers [23][24][25]. The difference in the starting age for TR appears to influence the effects of TR on adipocyte numbers, because when TR was started at a very early stage of a rat's life (0.7-1.1 weeks of age), it reduced both adipocyte number and size; however, when TR was started at 9-27 weeks of age, only adipocyte size was reduced [21][22][23][24].…”

“…One of the reasons for a TR-induced reduction in WAT mass might be hypotrophy of mature adipocytes [20][21][22][23][24][25][26], which has been associated with greater adipocyte lipolysis in exercise-trained subjects than in sedentary controls [27,28]. TR increases the association efficiency of the b-adrenergic receptor (b-AR) and stimulatory G protein, and decreases the amount of inhibitory G protein in the lipolytic response under the influence of catecholamines ( Fig.…”

“…The TR-induced reduction in the number of adipocytes appeared not to be due to apoptosis of mature adipocytes, but rather to suppressed adipocyte differentiation of stromal-vascular fraction (SVF) cells containing adipose tissue-derived stem cells (ADSC), which are present in WAT for differentiation into adipocytes, vascular endothelial cells, and the like [26,31,32]. Some of the possible mechanisms for the TR-induced inhibition of adipogenesis may be enhanced expression of pre-adipocyte factor-1, which inhibits adipocyte differentiation [33], and decreased expression of peroxisome proliferator-activated receptor c, the master regulator of adipocyte differentiation [34,35], through upregulation of the protein level of hypoxia-inducible factor-1a, which is also reported to inhibit adipogenesis [36], in SVF cells [26] (Fig. 2).…”

Human adipose tissue stem cells: relevance in the pathophysiology of obesity and metabolic diseases and therapeutic applications

“…In a murine model, exercise training was shown to largely inhibit the ability of SVF cells to differentiate into adipocytes and that this response could be mediated via up-regulation of HIF-1α expression (Ref. 95). Whether the exercise-mediated decrease in adipocytes in the WAT results from inhibition of ASC differentiation into mature adipocytes in humans remains to be established.…”