Study On The Mechanism Of Leptin Regulating The Onset Of Puberty In Mice

To further study leptin how to regulate onset of puberty following two experiments were conducted. In experiment 1,104 female mice were at random divided to two groups at day 21,one group was allowed access to food and water freely,and other group was restricted to take in food (70% food of first group),in experiment 2,156 female mice were divided to three groups at day 21 at random,group 1,the mice were injected daily with recombined human leptin (2 u g/g BW i.p.),group 2 with anti-leptin(6 u 1/gBW) and group 3 with saline. The results were as follows:in experiment 1,the basal levels of leptin and peak levels of LH were significantly higher in group 1 than that of group 2 after day 26(1.41 + 0.07ng/ml vs 1.17+0.04 ng/ml,P<0.05 and 0.89+0.11 mlU/ml vs 0.56+0.11 mlU/ml,P<0.05),the average body weight of vaginal opening mice was more heavy than not opening mice at same age in group 1(22.9+ 1.56g vs 20.2+0.90g,P<0.01);In experiment 2,the average body weight was 25.48+1.9g in leptin-treated mice compared with 28.39+1.94g in anti-leptin-treated mice (P<0.01),basal levels of serum LH were lower in anti-leptin-treated mice than in saline-treated mice and in leptin-treated mice during experiment (0.19 + 0.06mIU/ml vs 0.35+0.13mIU/ml,P<0.05 and 0.19+0.06mIU/ml vs 0.3 + 0.06mIU/ml,P<0.05),there were significant difference in peak levels and basal levels of leptin between leptin-treated and saline-treated mice (6.26 + 1.9 ng/ml vs 1.47 + 0.19 ng/ml,P<0.01 and 2.88 + 0.92 ng/ml vs 1.11 +0.27 ng/ml,P<0.01),On the other hand,leptin could stimulate surge of LH,and make the second peak of LH earlier appear in leptin-treated group than in saline-treated group,at 44 days,ratio of vaginal opening mice,in leptin-treated,anti-leptin-treated andsaline-treated mice,were 100%. 75% and 88%,receptively. These data suggest that the secretion of leptin and surge of LH is inhibited by restricted feeding mice,treatment with anti-leptin can suppress the peak levels and basal levels of LH,delay onset of puberty in mice,exogenous leptin could increase endogenous leptin secretion in vivo,and leptin induce surge of LH and onset of puberty. So. it is conclusion that leptin could control the onset of puberty by regulating reproductive endocrine in animal.