Exercise Training Enhances Tumor Necrosis Factor-α–Induced Expressions of Anti-Apoptotic Genes without Alterations in Caspase-3 Activity in Rat Epididymal Adipocytes

Abstract

ABSTRACT:The effect of exercise training on tumor necrosis factor-α (TNF-α) signaling was investigated in rat epididymal adipocytes. Incubation of isolated adipocytes with TNF-α (20 ng/ml) for 5 h enhanced the expression of the inhibitor apoptosis protein 2 (IAP2) gene without any enhancement of caspase-3 activity in both the sedentary control (C) and exercise-trained (TR) groups. However, the ability of TNF-α to enhance IAP2 gene expression was significantly greater in TR than in C rats. The basal expression of the IκB kinase β (IKKβ) gene and that of the BCL-x L gene were also higher in TR than in C rats. Mn-superoxidedismutase contents in adipocytes were higher in TR than in C rats. Moreover, no apoptotic nucleuses of adipocytes in response to acute exercise were observed in either group at least up to 5 h after exercise. Exercise training also enhanced the inhibitory effect of TNF-α on the gene expression of the fatty acid synthase (FAS), a lipogenic enzyme, suggesting that fatty acid synthesis may be reduced. Thus, exercise training enhanced TNF-α signaling directed toward the expressions of survival signals and the suppression of FAS gene expression.

Notice of Retraction: Exercise Improves Insulin Sensitivity May through Reduction of Inflammation and Oxidative Stress on Adipose Tissue

“…There is strong evidence for regular exercise can decrease the expression and levels of TNF-α in people with obese and insulin resistance [11]. These observations were paralleled by similar findings in rodent [12]. It has been demonstrated that increased expression of inflammation-related markers results in the increased HOAW-IR index.…”

“…Based on this, increased oxidative stress in adipocytes is one of the causes of insulin resistance. However, the regular exercise has long been valued for its benefits of reduction in oxidative stress, research has found that manganese-containing SOD (Mn-SOD) levels in adipocytes are significantly greater in exercise-trained rats compared with those in untrained rats [12], this result suggest that exercise may decreased the oxidative stress via the increased antioxidative enzymes activity in adipocyte. Recently a study has found that ROS generated during exercise act as signals to increase the production of enzymes relevant to adaptation of muscle cells to exercise [38].…”

“…Many studies have shown that regular exercise increases insulin sensitivity and decreases the risk of developing type 2 diabetes mellitus [9][10]. Additionally, other studies have confirmed that manganese-containing SOD (Mn-SOD) levels in adipocytes are significantly greater in exercise-trained rats compared with those in untrained rats, and regular exercise can decrease some adipose-derived inflammatory markers [11][12]. However, the exact mechanisms underlying the beneficial effects of regular exercise improve insulin sensitivity are not fully clear.…”

The Effects of Exercise Training on Obesity-Induced Dysregulated Expression of Adipokines in White Adipose Tissue

“…For example, increased expression of TNF- α in visceral WAT in mice that became obese after six weeks of consuming a high-fat diet can be suppressed by spontaneous running [25, 26]. Additionally, our studies showed that nine weeks of treadmill running decreased the TNF- α protein content of the rat WAT [27, 28], but some results have shown a contrasting increase after TR [24, 29, 30]. Studies regarding obese individuals have also examined the effects of TR on TNF- α expression in WAT.…”

“…Adipocytes have produced reactive oxygen, and obesity-induced increases in oxidative stress in WAT may be a cause of the dysregulated expression of inflammatory-related adipokines [88]. Studies have shown significantly lower levels of lipid peroxidation in WAT around the epididymis and retroperitoneum of rats that had undergone TR compared with a control group, and elevated protein levels of the antioxidant enzyme manganese superoxide dismutase (Mn-SOD) in the epididymal WAT of TR group rats [27, 28]. In that study, not only were protein levels of TNF- α and MCP-1 significantly lower in the epididymal WAT of the TR group, compared with those of the control group, the phosphorylation of extracellular signal-regulated kinase, which is activated by reactive oxygen and is important for the expression of MCP-1, also was reduced by TR in WAT around the epididymis and retroperitoneum [27, 89].…”