Abstract
BackgroundA sedentary lifestyle predisposes to cardiometabolic diseases. Lifestyle changes such as increased physical activity improve a range of cardiometabolic risk factors. The objective of this study was to examine whether functional changes in adipose tissue were related to these improvements.MethodsSeventy-three sedentary, overweight (mean BMI 29.9 ± 3.2 kg/m2) and abdominally obese, but otherwise healthy men and women (67.6 ± 0.5 years) from a randomised controlled trial of physical activity on prescription over a 6-month period were included (control n = 43, intervention n = 30). Detailed examinations were carried out at baseline and at follow-up, including fasting blood samples, a comprehensive questionnaire and subcutaneous adipose tissue biopsies for fatty acid composition analysis (n = 73) and quantification of mRNA expression levels of 13 candidate genes (n = 51), including adiponectin, leptin and inflammatory cytokines.ResultsAt follow-up, the intervention group had a greater increase in exercise time (+137 min/week) and a greater decrease in body fat mass (−1.5 kg) compared to the control subjects (changes of 0 min/week and −0.5 kg respectively). Circulating concentrations of adiponectin were unchanged, but those of leptin decreased significantly more in the intervention group (−1.8 vs −1.1 ng/mL for intervention vs control, P < 0.05). The w6-polyunsaturated fatty acid content, in particular linoleic acid (18:2w6), of adipose tissue increased significantly more in the intervention group, but the magnitude of the change was small (+0.17 vs +0.02 percentage points for intervention vs control, P < 0.05). Surprisingly leptin mRNA levels in adipose tissue increased in the intervention group (+107% intervention vs −20% control, P < 0.05), but changes in expression of the remaining genes did not differ between the groups.ConclusionsAfter a 6-month period of increased physical activity in overweight elderly individuals, circulating leptin concentrations decreased despite increased levels of leptin mRNA in adipose tissue. Otherwise, only minor changes occurred in adipose tissue, although several improvements in metabolic parameters accompanied the modest increase in physical activity.
Highlights
The number of obese individuals worldwide has increased dramatically during the last couple of decades
Estimates of the activity of stearoyl CoA desaturase (SCD) in adipose tissue have been positively correlated to insulin resistance [19] and obesity [20], possibly suggesting an increased desaturation of adipose tissue fatty acids by SCD in response to an unfavourable increase in saturated fatty acids. In this randomized controlled trial in overweight individuals we investigated whether increases in physical activity over a 6-month period induced changes in subcutaneous adipose tissue as assessed by changes in i) circulating adiponectin and leptin concentrations, ii) adipose tissue fatty acid composition, and iii) expression in adipose tissue of genes encoding key proteins
In the present analysis, using a subset of 68 year-old overweight-to-obese men and women exposed to physical activity on prescription in a randomized intervention trial for 6 months [3], we observed a decrease in circulating leptin concentrations, despite an increase in leptin mRNA in adipose tissue
Summary
The number of obese individuals worldwide has increased dramatically during the last couple of decades. A major contributor to the obesity epidemic in modern societies is a sedentary lifestyle and low levels of daily regulation, glucose and lipid handling capacities, hemodynamics, hormonal balance and inflammatory state [6,7,8]. All of these variables are recognised components of the unfavourable metabolic state called the metabolic syndrome. A sedentary lifestyle predisposes to cardiometabolic diseases Lifestyle changes such as increased physical activity improve a range of cardiometabolic risk factors. The objective of this study was to examine whether functional changes in adipose tissue were related to these improvements.
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