Kisspeptin-GPR54-GnRH神经元轴在雌性大鼠中枢性性早熟中的作用

Effect of Kisspeptin-GPR54-GnRH neuron axis in central precocious puberty of female rats

目的探讨Kisspeptin-GPR54-GnRH神经元轴在雌性大鼠中枢性性早熟(CPP)中的作用。方法选择雌性SD大鼠50只,随机分为对照1组(正常青春前期)、对照2组(正常青春早期)、对照3组(正常青春中期)、实验1组(性早熟青春早期)、实验2组(性早熟青春中期)各10只。实验组皮下注射N-甲基-DL-天冬氨酸(NMA)建立CPP模型。观察各组阴道开放时间及性周期,测量其子宫指数、卵巢指数、卵巢黄体出现个数、子宫壁厚度和血清黄体生成素;用Real-Time RT-PCR法检测下丘脑中的KISS-1 mRNA、GPR54 mRNA、促性腺激素释放激素(Gn-RH)mRNA表达;在电镜下观察各组下丘脑内分泌神经元的超微结构。结果实验组性发育起始时间早于对照组,实验组各检查指标明显高于对照1组(P均<0.05),实验1组与对照2组、实验2组与对照3组比较均无统计学差异。随着青春期发育,实验组和对照组大鼠下丘脑中KISS-1 mRNA、GPR54 mRNA、GnRH mRNA表达均逐渐升高,下丘脑内分泌神经元代谢逐渐活跃,分泌旺盛。结论应用NMA可建立理想的雌性大鼠CPP模型,随着大鼠青春期发育,其下丘脑中的KISS-1 mRNA、GPR54 mRNA、GnRH mRNA表达逐渐升高;提示Kisspeptin-GPR54-Gn-RH神经元轴在CPP的发生、发展中起重要作用。

Objective To study the effect of Kisspeptin-GPR54-GnRH neuron axis in central precocious puberty （CPP） of female rats. Methods Fifty female rats were randomly assigned to five groups, the first control group （normal prepuberty）, the second control group （early phase of normal puberty） , the third control group （metaphase of normal pu- berty）, the first experimental group （early phase of precocious puberty）, the second experimental group （metaphase of precocious puberty） , ten rats in each group. Experimental group received subcutaneous injection of N-methyl-DL-aspartate acid （NMA） in order to establish the central precocious puberty model. The vaginal open and estrous cycle of all rats were observed. The parameters of puberty were analyzed, which including index of ovary, index of uterus, incidence of corpora lutea, thickness of uterus and level of serum luteinizing hormone. The expressions of hypothalamic KISS-1 mRNA, GPR54 mRNA and GnRH mRNA were detected by Real-Time reverse transcription polymerase chain reaction （ Real-Time RT- PCR）. Uhrastrueture of hypothalamic endocrinic neurons was observed by electron microscope. Results The day of pu- berty onset in experimental groups was earlier than that of the control groups. The parameters in experimental groups were higher than those of the first control group. The parameters in the first experimental group were not obviously different from the second control group, as well as the second experimental group versus the third control group. With puberty process, the expressions of hypothalamic KISS-1 mRNA, GPR54 mRNA and GnRH mRNA in experimental or control groups all gradually increased. The hypothalamic endocrinie neurons were active in metabolism with prosperous secretion. Conclusion The central precocious puberty model of female rats could be perfectly established by way of NMA subcutaneous injec- tion. It is suggested that Kisspeptin-GPR54-GnRH neuron axis may play an important part in onset and development of CPP in view of the increase of KISS-1 mRNA, GPR54 mRNA and GnRH mRNA expressions in hypothalamus with puberty process.