شکوفه خردمند

The prevalence of obesity in postmenopausal women is higher compared to men. A decrease in estrogen with menopause leads to dysfunction in mitochondria. The purpose of this study is to investigate the effect of high intensity aerobic training(HIT) on the copy number of mitochondrial genome (mtDNAcn) and mitochondrial transcription factor A(Tfam) in visceral adipose tissue(VAT) in ovariectomized(OVX) rats fed with high-fat diet(HFD). 40 rats (8 weeks, 200±20 gr) were divided into 5 groups:1) normal diet (ND), 2) ND+OVX, 3) HFD, 4) HFD+OVX, and 5) HFD+OVX+HIT. HIT performed aerobic training (80-85% of maximum oxygen consumption) for 8 weeks/5 sessions/42 minutes.48 hours after the last training session, VAT samples were taken to evaluate mtDNAcn and Tfam gene expression by qRT-PCR method. ANOVA and LSD tests were used to compare the differences between groups. OVX and HFD didn’t lead to a significant change in Tfam gene expression, but caused a significant decrease in the mtDNAcn compared to the control group. HIT caused a significant increase in Tfam gene expression compared to the control group and Tfam gene expression and mtDNAcn compared to the HFD+OVX. Hence, HIT improves mitochondrial function through mtDNAcn and Tfam gene expression in VAT in OVX rats fed by HFD.

Inflammatory factors and related disorders (including insulin resistance) increase with the onset of menopause in overweight women; thus the aim of the present study was to investigate the effect of eight weeks of aerobic exercise training on plasma levels of calprotectin and insulin resistance in overweight post-menopausal and peri-menopausal women. 

Twenty seven overweight women (BMI>25 kg/m2) participated in this study. Subjects were divided into two groups including 13 post-menopausal women (mean age 53.46‌±‌‌5.76 years), and 14 peri-menopausal women (mean age 32.50±7.85 years). The training program consisted of eight weeks of aerobic exercise training, three sessions per week, up to 40-80% of maximal reserve heart rate; each session lasted 25 minutes in the first week and reached to 45 minutes in the 8th week of training. Plasma levels of calprotectin, insulin, glucose, and insulin resistance index (HOMA-IR) were measured before and 48 hours after the end of training. Paired t-test was used to determine intragroup changes; while analysis of covariance (ANCOVA) test were applied to compare intergroup changes at the significant level of p<0.05. 

The results of paired t-test showed that plasma levels of calprotectin increased significantly in both post-menopausal (p=0.01) and peri-menopausal (p=0.04) women after exercise; but the analysis of covariance test did not show any significant differences (p=0.80) between two groups. Moreover, plasma insulin (p=0.009) concentration and insulin resistance (p=0.03) significantly reduced in post-menopausal women, while in peri-menopausal women was associated with a significant increase (p=0.01) in insulin resistance. 

The results of this study showed that aerobic exercise training increases the levels of calprotectin in overweight post-menopausal and peri-menopausal women, and this increase appears to be independent of changes in insulin and insulin resistance in these women.

 Exercise improves sensitivity to insulin by reducing some adipokines including chemerin. However, the effect of endurance exercise and high-intensity intermittent exercise on chemerin level and insulin resistance in obese male rats is still unknown.

In this study 27 male rats were randomly divided into 4 groups of sedentary control (n=6), endurance exercise (n=8), high-intensity intermittent exercise (n=8) and untreated obese control (n=5). Both endurance and high intensity intermittent exercise groups performed exercises for 8 weeks. The plasma level of chemerin was measured by ELISA method.

This study obtained its ethical approval form the Research Ethics Committee of Sport Sciences Research Institute (Code: IR.SSRI.REC.1398.55).

The chemerin level was significantly reduced in the endurance group compared to the untreated obese control group (P<0.01), but it had no significant change compared to the sedentary control group. Moreover, the plasma level of chemerin in the high-intensity intermittent group was not significantly different from that of untreated obese control group and sedentary control group (P>0.05) and chemerin level reduction in the endurance group was significant compared to the high-intensity intermittent group (P<0.05). Furthermore, there was no significant difference in the insulin resistance reported in high-intensity intermittent group compared to that of endurance group (P>0.05), but its difference in high-intensity intermittent and endurance training groups was significant compared to that of untreated obese control and sedentary control groups (P<0.05).

Both endurance and high-intensity intermittent exercises can reduce insulin resistance which can be due to the reduction of chemerin plasma level and weight loss.