| Obesity is a kind of nutritional imbalance disease caused by intaking more energy than consumption under the genetic and environmental factors, and has become a worldwide epidemic. Obesity can result in all kinds of chronic diseases such as diabetes mellitus and cardiovascular disease. Metabolic Syndrome(MS) is a new concept developmented recently. It refers to a series of metabolic disorders in identical individual, including dyslipidemia, abdominal obesity, elevated blood pressure, and impaired glucose tolerance. And MS is a risk factor of cardiovascular disease and type 2 diabetes. The existing epidemiological investigations showed the prevalence of MS is higher in obese population than that of the normal weignt population. Obesity can contribute to the incidence of metabolic syndrome obviously although its underlying pathophysiology is unclear.Adipose tissue can not only store energy, but also secrete a variety of bioactive substances. Leptin(LEP) and adiponectin(ADIPO) are two adipokines secreted by adipocytes. The main physiological function of leptin can act on the hypothalamus and reduce food intake and increase energy expenditure, at last result in weight loss. The level of leptin is higher in obese bosy compared with the normal. Recent studies show that leptin may also act in peripheral tissues, such as adipose tissue, muscle, liver, and so on. And it is involved in blood pressure regulation and lipid metabolism. So leptin may be a risk factor of MS. Adiponecein is another adipose tissue-specific adipokine. However plasma Adiponecein level is lower in obese individual than that of normal . Adiponecein has many biofunctions, including the regulation of blood glucose and lipids, adiponecein can alao improve the sensitivity of insulin. So low adiponecein level may be a risk factor of MS.To date, the relatipnship of leptin, adiponectin and MS is unclear. The incidence of obesity and MS is higher and obesity-related complications are less in adolescents than that in adults. The study was designed to explore the relationship between leptin, adiponecein and MS in adolescents to provide a therotical basis for further research.Objectives1 To understand the changes of blood pressure and plasma level of lipids, blood glucose, leptin and adiponecein.2 To explore the relationship of serum leptin, adiponecein and MS.Subjects and MethodsWe enrolled 86 obese(male: 45, female: 41)and 91 weight normal (boy: 51, girl: 40) adolescents aged 13～15years. Height, weight, waist circumference(WC), hip circumference, systolic blood pressure (SBP) and diastolic blood pressure(DBP)were measured, body mass index(BMI) and waist-hip ratio(WHR) were calculated. Morning fasting venous blood samples were collected and blood glucose(GLU), blood triglyceride(TG), high-density-lipoprotein-cholesterol(HDL-C) were measured. Serum insulin and leptin were measured by radioimmunoassay(RIA), and serum adiponectin were measured by enzymelinked immunosorbent assay(ELISA). MS was defined according to the modified Cook's definition. Numerical variables were compared using one-sample T test and one-way ANOVA, Correlation of variables was evaluated using Pearson's correlation coefficient and partial correlation coefficient. Classification variables were tested using X~2 test and logistic regression analysis.Results1 The average levels of triglyceride, systolic blood pressure, insulin, leptin were significantly higher and the levels of high-density-lipoprotein-cholesterol, adiponectin were lower in the obese groups compared with the normal weight groups in boys(TG: 1.74±0.91mmol/l & 0.76±0.22mmol/l; SBP: 123.60±14.11mmHg& 111.38±10.18mmHg; INS: 28.72±13.79mIU/l, 16.74±6.53 mIU/l; LEP: 19.49±6.94μg/l & 8.08±4.15μg/l; HDL-C: 1.07±0.25mmol/l & 1.36±0.33mmol/l; ADIPO: 3.50±1.50mg/l & 5.28±2.68mg/l, all P<0.05). In the girls, the average levels of triglyceride, systolic blood pressure, diastolic blood pressure, insulin, leptin were higher and High-density-lipoprotein-cholesterol, adiponectin were lower compared with the normal group(TG: 1.43±0.64mmol/l & 0.91±0.25mmol/l; SBP: 115.48±10.47mmHg & 105.95±9.71 mmHg; DBP: 73.73±8.84 & 66.53±8.53; INS: 24.51±10.93 mIU/l & 17.12±5.45 mIU/l; LEP: 27.55±4.23μg/l & 17.93±5.08μg/l; HDL-C: 1.13±0.23mmol/l & 1.48±0.33mmol/l; ADIPO: 4.66±3.06mg/l & 6.33±3.64mg/l, all P<0.05). The prevalence of MS was 30.23% in the obese group which was higher compared with the normal group (P<0.05).2 Serum leptin levels was lower in boys compared with that in girls(obese groups: 19.49±6.94μg/l & 27.55±4.23μg/l; normal groups: 8.08±4.15μg/l & 17.93±5.08μg/l, all P<0.01); and adiponectin levels was also lower in boys compared with that in girls than in girls(obese groups: 3.50±1.50 mg/l & 4.66±3.06 mg/l; normal groups: 5.28±2.68 mg/l & 6.33±3.64 mg/l, all P<0.05).3 In simple linear correction analysis, leptin was positively correlated with BMI, waist circumference, serum insulin, triglyceride, systolic blood pressure in both boy and girl groups (BMI: r= 0.722 & r= 0.812; WC: r= 0.778 & r= 0.796; INS: r=0.625 & r=0.438; TG: r= 0.576 & r= 0.389; SBP: r=0.415 & r =0.359, all P<0.05), and only positively correlated with diastolic blood pressure in girls(r=0.395, P<0.05). And inversely correlated with high-density lipoprotein cholesterol (r=-0.347 & r=-0.535; P<0.01). But after controlling BMI, leptin merely correlated with serum insulin (partial r=0.402, P<0.05) in boys.4 In simple linear correlation, adiponectin inversely correlated with BMI, waist circumference, fasting serum insulin, triglycerides in both boys and girls(BMI: r=-0.350 & r=-0.299; WC: r=-0.405 & r=-0.317; INS: r=-0.232 & r=-0.327; TG: r=-0.301 & r=-0.240, all P<0.05) and and positively correlated with high-density lipoprotein cholesteral in all subjects(male: r=0.251, female: r=0.260; P<0.05). But after controlling body mass index, adiponectin did not correlate with fasting serum insulin, triglycerides, high-density lipoprotein cholesteral(P>0.05).5 BMI positively correlated with triglyceride, systolic blood pressure, diastolic blood pressure, insulin in both boys and girls(TG:r=0.664 & r=509; SBP: r=0.532 & r=0.562; DBP: r=0.24 & r=0.513; INS: r= 0.504 & r= 0.545, all P<0.05), and negatively correlated with high-density-lipoprotein-cholesterol in all subjects(male: r= -0.419, female: r=-0.599, P<0.05). After controlling leptin and adiponectin, BMI sfill correlated with the triglyceride, High-density-lipoprotein-cholesterol, systolic blood pressure, diastolic blood pressure in boys and girls(TG: partial r=0.407 & partial r=0.364; SBP: partial r=0.368 & partial r=0.509; DBP: partial r=0.218 & partial r=0.393; HDL-C: partial r=-0.259 & partial r=-0.337, all P<0.05). After controling leptin, BMI positively correlated with insulin in girls and did not correlat with insulin in boys(P>0.05).6 The result of logistic regression showed BMI and insulin were the risk factors of MS in obese adolescents(BMI: OR=1.974; INS: OR=1.884, P<0.05).Conclusions1 There are lipids abnormality, increased blood pressure, increaced serum leptin and insulin level, decreaced adiponectin level in obese adolescents. And the prevalence of MS is higher in obese adolescents than normal weight adolescents.2 Leptin correlates with triglyceride, systolic blood pressure, diastolic blood pressure, High-density-lipoprotein-cholesterol; and adiponectin correlates with triglyceride, High-density-lipoprotein-cholesterol. The increased serum leptin and decreased adiponectin may be related with the metabolic syndrome in obese adolescents.3 Leptin correlates with serum insulin. Leptin may be one of the main causes of the increased serum insulin in male adolesents.4 The degree of obesity and increased serum insulin level are risk factors of the MS. |
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