title: Impact of aging and beta3-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 beta3-adrenergic-receptor (beta3-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 EE(LBM) 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 beta3-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 beta3-AR polymorphism, suggesting that this age-related decrease in thermogenic response may be involved in the development of obesity among middle-aged men.
authors.affiliation: Department of Nutritional Science, Faculty of Health and Welfare, Okayama Prefectural University, Okayama 719-119 7, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Nagai
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakane
authors.forename: Toshio
authors.initials: T
authors.lastname: Moritani
mesh_terms: D000328:Adult; D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D002648:Child; D004041:Dietary Fats / Q000378:metabolism*; D004562:Electrocardiography / Q000379:methods; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D005502:Food; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011110:Polymorphism, Genetic / Q000235:genetics*; D019518:Postprandial Period / Q000502:physiology; D022702:Receptors, Adrenergic, beta-3 / Q000235:genetics* / Q000378:metabolism; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000378:metabolism*; D022722:Thermogenesis / Q000235:genetics* / Q000502:physiology*
chemical_list: D004041:Dietary Fats; D022702:Receptors, Adrenergic, beta-3