Decreased plasma levels of brain-derived neurotrophic factor and its relationship with obesity and birth weight in obese Japanese children

Background: Brain-derived neurotrophic factor (BDNF) plays important roles in the central regulation of food intake and body weight control. However, little is known about the role of BDNF in childhood obesity.

Objective: To investigate the relationship between plasma levels of BDNF and anthropometric factors, metabolic derangements due to obesity, adipocytokine levels and birth weight in obese Japanese children.

Subjects and methods: Sixty-six obese Japanese children aged from 5 to 15 years old were enrolled. The age-matched control group consisted of 32 non-obese healthy children. The plasma levels of BDNF and adipocytokines (leptin and adiponectin) were assayed using ELISA techniques.

Results: The mean BMI Z-scores were -0.67, +2.15 and +3.39 for the non-obese control children, obese (BMI ≥ 90th percentile, <99th percentile) and morbidly obese (BMI ≥ 99th percentile), respectively. The plasma levels of BDNF were significantly decreased in the morbidly obese children compared with the levels in the obese and non-obese control children (507 ± 33 pg/ml vs. 626 ± 46 pg/ml, 621 ± 35 pg/ml, p < 0.05). Univariate linear regression analysis showed that the plasma level of BDNF was positively correlated with birth weight (r = 0.264, p < 0.05) and inversely correlated with the BMI Z-score (r = -0.314, p < 0.05). Multivariate forward stepwise linear regression analysis revealed that the birth weight and BMI Z-score are independent predictors of the plasma BDNF level.

Conclusion: The plasma level of BDNF, which is decreased in morbidly obese children, is associated with birth weight and the BMI Z-score. Our results suggest that BDNF may play important roles in the development and pathophysiology of childhood obesity.