Objective: To study the effects of leptin on puberty development in children.
Methods: Three hundred obese and 300 healthy children without taking any medication or having evidence of endocrine or metabolic diseases were studied. Their ages of first spermatorrhea and menarche were surveyed, and blood levels of leptin, sex hormones, growth hormone (GH) and insulin (INS) were measured.
Results: With increased of age, blood levels of leptin appeared from low to high and from high to low again in the boys, with (1.04 +/- 0.21) nmol/L to (1.20 +/- 0.27) nmol/L and to (0.66 +/- 0.10) nmol/L in the obese group, and with (0.31 +/- 0.06) nmol/L to (0.45 +/- 0.10) nmol/L and to (0.19 +/- 0.04) nmol/L in the control group. While blood level of leptin appeared an increasing trend in girls, with (0.89 +/- 0.15) nmol/L to (1.39 +/- 0.23) nmol/L in the obese group, and (0.46 +/- 0.08) nmol/L to (0.88 +/- 0.18) nmol/L in the control group. Levels of sex hormones also appeared an increasing trend in the all groups. Levels of GH showed an abrupt increased at certain ages, different in boys from girls (14-15 years of age in boys and 13-14 in girls). In the all ages, serum levels of leptin and INS were higher in the obese group than those in the control group, while the level of GH was lower in the obese group than that in the control group. Serum level of leptin was higher in the obese group of both boys and girls than that in the control group, with (0.71 +/- 0.17) nmol/L and (0.30 +/- 0.04) nmol/L and (1.11 +/- 0.21) nmol/L and (0.70 +/- 0.18) nmol/L, respectively. Ages at first spermatorrhea and menarche were much earlier in the obese children than those in the controls, with (12.5 +/- 1.2) and (13.2 +/- 1.2) years of age in boys and (11.6 +/- 0.8) and (12.8 +/- 0.9) in the girls, respectively. Blood levels of leptin was higher in the girls than that in the boys. Age at menarche and earlier in the girls than that of first spermatorrhea in the boys. Blood level of testosterone correlated inversely with that of leptin in boys, while that of estradiol correlated with that of leptin in girls. Level of GH correlated inversely with that of leptin in boys and correlated with that in girls. Level of INS correlated with that of leptin in the control girls.
Conclusions: Leptin might have an effect on initiation of puberty in children, possibly with more importance in girls than in boys. The gender difference in the degree of correlations between levels of leptin and GH may cause their difference in the ages at sudden growth in boys and girls. The gender difference in the degree of correlation between levels of leptin and sex hormone may cause their difference in the ages at first spermatorrhea and menarche in both boys and girls.