Impact of aging and β3-adrenergic-receptor polymorphism on thermic and sympathetic responses to a high-fat meal

Abstract

The present study was designed to investigate the effect of aging and β3-adrenergic-receptor (β3-AR) polymorphism on the thermic effect of meal (TEM) and sympathetic nervous system (SNS) response to a high-fat meal in 13 boys, 12 young men, and 11 middle-aged men. SNS activity was assessed via power spectral analysis of heart rate variability. Significantly higher very-low-frequency (VLF) components associated with thermogenic SNS activity and energy expenditure per lean body mass (EE LBM) were observed in boys during the pre- and postprandial periods. There were no significant differences in VLF and EELBM in the preprandial period between the young and middle-aged men. After feeding, however, the middle-aged men showed a significantly lower TEM (% test-meal energy) and VLF compared to the young men. A multiple regression analysis revealed that age was the only significant variable contributing to both TEM and VLF, but β3-AR polymorphism and percentage of body fat were not statistically significant. In conclusion, age likely has a greater influence on TEM and SNS thermoregulation than genetic factors such as β3-AR polymorphism, suggesting that this age-related decrease in thermogenic response may be involved in the development of obesity among middle-aged men.