Abstract
The aim of the present study was to assess the effects of endurance training on leptin levels and adipose tissue gene expression and their association with insulin, body composition and energy intake. Male Wistar rats were randomly divided into two groups: trained (N = 18) and sedentary controls (N = 20). The trained group underwent swimming training for 9 weeks. Leptin and insulin levels, adiposity and leptin gene expression in epididymal and inguinal adipose tissue were determined after training. There were no differences in energy intake between groups. Trained rats had a decreased final body weight (-10%), relative and total body fat (-36 and -55%, respectively) and insulin levels (-55%) compared with controls (P < 0.05). Although trained animals showed 56% lower leptin levels (2.58 +/- 1.05 vs 5.89 +/- 2.89 ng/mL in control; P < 0.05), no difference in leptin gene expression in either fat depot was demonstrable between groups. Stepwise multiple regression analysis showed that lower leptin levels in trained rats were due primarily to their lower body fat mass. After adjustment for total body fat, leptin levels were still 20% (P < 0.05) lower in exercised rats. In conclusion, nine weeks of swimming training did not affect leptin gene expression, but did lead to a decrease in leptin levels that was independent of changes in body fat.
Highlights
Obesity currently qualifies as a pandemic and its sequelae include diabetes mellitus, hypertension, cardiac diseases, dyslipidemia and some forms of cancer [1]
The aim of the present study was to investigate the effects of endurance training on leptin levels and its association with other variables such as insulin, body fat mass, energy intake and epididymal adipose tissue and inguinal adipose tissue ob mRNA expression
Our results indicate that nine weeks of swimming training improved insulin sensitivity and reduced total fat mass, body weight, serum insulin and leptin levels, but not leptin gene expression in rats
Summary
Obesity currently qualifies as a pandemic and its sequelae include diabetes mellitus, hypertension, cardiac diseases, dyslipidemia and some forms of cancer [1]. Leptin is expressed and secreted primarily by white adipose tissue and acts through both peripheral and central receptors [3]. The latter are located mainly in the hypothalamus [4] in areas related to the control of energy intake and expenditure, thereby suggesting the role of leptin as a central “adiposity signal” in energy homeostasis [5]. Leptin levels are strongly and positively correlated with body fat mass [6,7] and leptin expression and secretion seem to be higher in epididymal adipose tissue than in inguinal adipose tissue in rats [8]. Weight loss and fasting are associated with reduced leptin levels while weight gain is associated with an increase in the concentration of this hormone [7]
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