Nagai Narumi, Matsumoto Tamaki, Kita Hiroko, Moritani Toshio
Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Obes Res. 2003 Jan;11(1):25-32. doi: 10.1038/oby.2003.6.
The autonomic nervous system (ANS) plays an important role in regulating energy expenditure and body fat content; however, the extent to which the ANS contributes to pediatric obesity remains inconclusive. The aim of this study was to evaluate whether sympathetic and/or the parasympathetic nerve activities were altered in an obese pediatric population. We further examined a physiological association between the duration of obesity and the sympatho-vagal activities to scrutinize the nature of ANS alteration as a possible etiologic factor of childhood obesity.
Forty-two obese and 42 non-obese healthy sedentary school children were carefully selected from 1080 participants initially recruited to this study. The two groups were matched in age, gender, and height. The clinical records of physical characteristics and development of the obese children were retrospectively reviewed to investigate the onset and progression of obesity. The ANS activities were assessed during a resting condition by means of heart rate variability power spectral analysis, which enables us to identify separate frequency components, i.e., total power (TP), low-frequency (LF) power, and high-frequency (HF) power. The spectral powers were then logarithmically transformed for statistical testing.
The obese children demonstrated a significantly lower TP (6.77 +/- 0.12 vs. 7.11 +/- 0.04 ln ms(2), p < 0.05), LF power (6.16 +/- 0.12 vs. 6.42 +/- 0.05 ln ms(2), p < 0.05), and HF power (5.84 +/- 0.15 vs. 6.34 +/- 0.07 ln ms(2), p < 0.01) compared with the non-obese children. A partial correlation analysis revealed that the LF and HF powers among 42 obese children were negatively associated with the duration of obesity independent of age (LF: partial r = -0.55, p < 0.001; HF: partial r = -0.40, p < 0.01). The obese children were further subdivided into two groups based on the length of their obesity. All three spectral powers were significantly reduced in the obese group with obesity of >3 years (n = 18) compared to the group with obesity of <3 years.
Our data indicate that obese children possess reduced sympathetic as well as parasympathetic nerve activities. Such autonomic depression, which is associated with the duration of obesity, could be a physiological factor promoting the state and development of obesity. These findings further imply that preventing and treating obesity beginning in the childhood years could be an urgent and crucial pediatric public health issue.
自主神经系统（ANS）在调节能量消耗和身体脂肪含量方面发挥着重要作用；然而，ANS对儿童肥胖的影响程度仍无定论。本研究的目的是评估肥胖儿童群体中交感神经和/或副交感神经活动是否发生改变。我们进一步研究了肥胖持续时间与交感-迷走神经活动之间的生理关联，以审视ANS改变作为儿童肥胖可能病因的本质。
从最初招募的1080名参与者中精心挑选出42名肥胖和42名非肥胖的久坐不动的健康学童。两组在年龄、性别和身高方面进行了匹配。回顾性分析肥胖儿童的身体特征和发育的临床记录，以调查肥胖的发病和进展情况。通过心率变异性功率谱分析在静息状态下评估ANS活动，该分析使我们能够识别不同的频率成分，即总功率（TP）、低频（LF）功率和高频（HF）功率。然后对频谱功率进行对数转换以进行统计检验。
与非肥胖儿童相比，肥胖儿童的TP（6.77±0.12对7.11±0.04 ln ms²，p<0.05）、LF功率（6.16±0.12对6.42±0.05 ln ms²，p<0.05）和HF功率（5.84±0.15对6.34±0.07 ln ms²，p<0.01）显著降低。偏相关分析显示，42名肥胖儿童中的LF和HF功率与肥胖持续时间呈负相关，与年龄无关（LF：偏r=-0.55，p<0.001；HF：偏r=-0.40，p<0.01）。根据肥胖持续时间，肥胖儿童进一步分为两组。与肥胖<3年的组相比，肥胖>3年的肥胖组（n=18）的所有三种频谱功率均显著降低。
我们的数据表明，肥胖儿童的交感神经和副交感神经活动均降低。这种与肥胖持续时间相关的自主神经抑制可能是促进肥胖状态和发展的生理因素。这些发现进一步表明，从儿童期开始预防和治疗肥胖可能是一个紧迫且关键的儿科公共卫生问题。
