Study On Relationship Between Brain-derived Neurotrophic Factor And Simple Obesity In Children

Background and Objective: Obesity is a highly prevalent disease in modern life style. Simple obesity in children, which is enormously doing harm to human's health, has become one of the most nutritional maladies in children of almost all countries except few poor. In obese patients,Over 95% characterizes leptin resistance,and mostly concomitantly characterizes insulin resistance. To improve leptin resistance and insulin resistance is a effective measure to cure obesity and related intercurrent syndromes.However, because people haven't open out the mechanism of leptin resistance and insulin resistance,how to ameliorate leptin resistance and insulin resistance in obese man is a hurdle which almost can't be conquered in obesity study. Scientists recently found that BDNF was associated with the genesis of obesity. Rats who lack BDNF manifest excessively eating behaviour and reduced locomotor activity and overmuch adipocyte hyperplasia and adiposity. When obese rats model were administered BDNF, the leptin resistance and insulin resistance of them would be lightened and their obesity would meliorate.It is infrequent that clinic data about the change of serum BDNF in obese patients.We only searched one literature about it in the world,and the result in the article was not ideal. In this study,we test serum BDNF and insulin levels through ELISA and measure serum leptin concentrations by RIA in children, observe the difference of serum BDNF levels between simple obesity children and healthy children whose weight are normal, probe into the relativity between human obesity and leptin resistance, the relativity between human obesity and insulin resistance,and the influence which BDNF exert on hepatic function and blood lipid. The study will instruct the therapy and diagnosis on children obesity.Methods: We choose 37 simple obesity children and 31 healthy children by physical examination from several nursery schools in Fuzhou. Simple obesity was diagnosed under WHO's recommendation which applied to weight for height method. When a child weighs 20% standard weight more than the standard weight of the same height,after excluding secondary obesity,he will be diagnosed simple obesity.Secondary obesity includes Cushing's syndrome, Froelich syndrome, Laurence-Moon-Biedl syndrome and Prader-Willi syndrome, in which some of the patients have taken prednisone for a long period, some go with other symptoms such as particular fat distribution and abnormity in limb and aptitude. Healthy children weigh 90% ~ 110% of standard weight of the children whose height are same. Detect serum BDNF and insulin levels through ELISA and examine serum leptin concentrations through RIA in children,assay hepatic function and blood lipid in clinical laboratory of PLA's Fuzhou general hospital. Process the data by SAS statistic software,compare the difference of serum BDNF levels between simple obesity and healthy children, observe the relativity between human BMI and serum BDNF levels, analyze how serum BDNF levels affect serum leptin,insulin,hepatic function and blood lipid.Results:(l)Comparing with the healthy children,obese children significantly expressed higher BMI (P<0.0001)and higher serum leptin levels (P< 0.0001 )and higher serum insulin levels (P<0.0001)and lower serum BDNF levels (P=0.0008).(2)In the two group(obese VS healthy),there were no significant difference in ALT (P = 0.2199) and AST (P = 0.5457) and TC (P = 0.0278,but no statistic significance in the mass) and TG (P=0.0556) and HDL-C (P=0.4572) and LDL-C(P=0.0692).(3)In the two group(Boy VS Girl),there were no significant difference in every index(BMI,P=0.0604; BDNF, P=0.0715; INS, P=0.4714; LEP, P=0.5035; ALT, P=0.2182; AST, P=0.8463; TC, P=0.7103; TG, P=0.1458; HDL-C, P=0.3665; LDL-C, P=0.6976).(4)Through multiple linear regression,,we educed the regression equation interrelated to serum BDNF levels about serum leptin levels: LEP = -9.6503+0.835BMI-0.00001636BDNF+0.2785554ALT.We also educed the regression equation interrelated to serum BDNF levels about serum insulin levels: INS=-14.9727613+2.12556079BMI-0.00010109BDNF.But we couldn't ecuced the regression equation interrelated to serum BDNF levels about ALT ,AST ,TC,TG or HDL-C.(5)Serum BDNF levels were in negatively correlative trend with BMI(R=-0.2348, P=0.0577).Even though we eliminate the effect of BMI,serum leptin levels and serum insulin levels were both negatively correlated with serum BDNF levels. (BDNF and leptin: r=-0.2455, P = 0.0487<0.05; BDNF and insulin: r=-0.2878, P=0.0201<0.05)= ALT,AST,TC,TG,HDL-C and LDL-C were not found significant correlations with serum BDNF levels.(6)Serum leptin levels were positively correlated with serum insulin levels ( r=0.37878 , P = 0.0017<0.05 ) .The regression equation was LEP = 7.9208+1.5365INS (P=0.0017<0.05) .But when eliminated the effect of BMI,there was no correlations between them.Conclusion:(l)Obese children lack BDNF, and children's serum BDNF levels are negatively correlated with BMI.(2)Obese children characterizes leptin resistance and concomitantly characterizes insulin resistance. Their serum leptin and insulin are in a very high level and are mostly affected by BMI and serum BDNF levels.And serum BDNF levels are their independent factors which are negatively correlated with them.(3)Hepatic function and blood lipid don't significantly change in obese children.ALT,AST and serum BDNF levels aren't correlated with serum BDNF levels.(4)It is successful that administering BDNF lighten the leptin resistance and insulin resistance and reduce blood lipid in animals.This study attests to that the leptinresistance and insulin resistance of obese children are related to deficiency of serum BDNF.From these we conclude that BDNF maybe ease obesity and can be applied to diagnose obesity in clinic.(5)Boy and girl in 4~6 years old don't deffer in BMI,serum BDNF ,serum LEP,serum INS ,blood lipid and hepatic function.