Discussion Of Relationship Between Leptin And Female Puberty

Puberty is a specific stage during which the sex hormones secrete and the gonads mature. Over the last century there has been a trend toward earlier onset of puberty and menarche in affluent societies, attributed primarily to the improvement in nutritional status. However, the mechanism still ecudes gynecologists. Kennedy and Mitra 35 years ago, which yielded the contemporary hypothesis that the timing of puberty is ultimately based on energetics. They believed that the first transition between an infertile and fertile state (puberty) is tightly coupled to a change in somatic metabolism. The onset of menarche was closely related with the achievement of a certain body weight or percent body fat . At the end of 1994, Zhang and his colleagues succeeded in positional cloning of the mouse obese gene and its human homologue. The obese gene product, leptin, is a 167 aminoacid and alGKda protein hormone that is mainly produced and secreted by white adipocytes. Leptin could decrease food intake and increase energy expenditures, regulate fat stores. Recently, the relationship between leptin and reproduction has been attracted more interest. Chehab et al found that the ob/ob mice lacking of endogenous leptin with obese and infertile2002 Wrzwent with hypogenesis of the hypothalamic-pituitary-gonad axis permanently, while treatment with leptin could restore fertility. After injecting healthy prepubescent female mice with leptin, they would advance sex maturation and enter estrous cycle sooner. In human, Donny Strosberg and Tarik Issad found individuals with ob gene mutation remain prepubertal with hypogonadotrophic hypogonadism. Hence, Barash suggested that leptin could be a metabolic signal acting on hypothalamic-pituitary-ovary axis and trigger the onset of puberty.The reports about leptin acting on puberty is not less, but it is controversial that how leptin triggers puberty and whether leptin is the unique peripheral signal. In our country, the studies only involve in the relationship between leptin and body fat or body mass index.The purpose of research was to study the relationship of leptin and Lh\ FSHv Ej.to search for the effect of leptin acting on pituitary and ovary, to explore the mechanism of leptin triggering puberty.Materials and MethodsBlood samples were obtained from 167 healthy schoolgirls, age from ten to fourteen years old, selected from Jinhua region randomly. Serum leptin > LH% FSH and î–¥?were measured by radioimmunoassay(RIA). We recorded each girl' s height and weight, calculated body mass index(BMI). At the same time, we knew about menarche and recorded menarche age. Those girls before menarche were traced for one and a half years and recorded menarche age in time.ResultsSerum leptin levels were positively correlated with BMI in 167 girls (r=0. 813, P<0. 01). After subdivided with age, leptin levels of each subgroup were also positively correlated with BMI. (10-year group:r=0. 579, P<0. 01; 11-year2002 *#Dfigroup: r=0. 731,P<0.01; 12-year group: r=0. 708, P<0.01; 13-year group: r= 0.809, P<0.01).Serum leptin values were positively correlated with age(r=0. 605, P<0. 01). With the pubertal development, leptin concentrations of the girls increased steadily. Serum leptin levels of 12-year girls and 13-year girls were 3.0 times and 3.2 times of that of 11-year girls respectively (P<0.01). At the same time, serum ?, LH and FSH concentrations were also increased significantly(P<0. 01). Serum leptin concentrations were negatively correlated with estriol(r=-0.543, P<0.01) and were positively correlated with LH (r=0. 622, P<0. 01)and FSH(r=0. 486, P<0. 01). Subdivided with age, serum leptin values had no correlation with ?, LH and FSH. Serum leptin levels were negatively correlated with estriol(r=~0. 504, P<0.01) and positively correlated with LH (r=0. 642, P<0. 01) and FSH(r=0. 460, P<0. 01) before menarche. After menarche, serum leptin values had no correlation with E2, LH and FSH. BMI was found to be the most important one among the factors which affect the leptin l...