Role of Orexin-A in the initiation of hypothalamic-pituitary-gonadal axis

doi:10.11852/zgetbjzz2020-0917

Abstract

Abstract: Objective To analyze the effects of Orexin-A on sexual development, serum levels of luteinizing hormone(LH), follicle stimulating hormone(FSH), estradiol(E2), Leptin and Kisspeptin, in order to explore the role of energy metabolism in the initiation of hypothalamic- pituitary-gonadal axis (HPGA). Methods In June 2018, 100 five-days-old female SPF SD rats were randomly divided into 4 groups: the control group, the precocious puberty group, the Orexin-A group, the Orexin-A+Orexin-1 receptor (OX1R) antagonist group, with 25 rats in each group. Each rat in the later three groups was subcutaneously injected with a mixture (25μl) of ethanol and ethylene glycol with 300μg of danazol to establish the precocious puberty model, while rats in the control group were injected with the same volume of danazol-free ethanol and ethylene glycol. Rats in the Orexin-A group were injected with 0.5 nmol/L Orexin-A 5μl once daily via lateral ventricle at 15 days old, and rats in the Orexin-A+OX1R antagonist group were injected with 0.5 nmol/L Orexin-A 5μl and 30 nmol/L OX1R antagonist 5μl once daily via lateral ventricle at 15 days old. The levels of serum sex hormones, Kisspeptin and Leptin at prepuberty, onset puberty and post puberty stage were tested. The vaginal opening time in different groups was compared, and the levels of serum sex hormones, Kisspeptin and Leptin were compared in different groups and periods. Results 1) The first vaginal opening time in the precocious puberty group was earlier than that in the control group (H=3.092,P=0.012,P＜0.05). 2) It was found that the LH, E2, Kisspeptin and Leptin levels of the Orexin-A group were lower than those of the precocious puberty group at prepuberty stage (t=-3.082,-2.476,-3.732,-3.289,P＜0.05). However, there were no significant differences on other hormone level except Kisspeptin(t=-4.486,P<0.05) between the precocious puberty group and the Orexin-A+OX1R antagonist group((t=-2.469,-2.771,P＞0.05). During puberty onset stage, the LH and Leptin levels in the Orexin-A group was lower than those in the precocious puberty group(P＜0.05). However, there were no significant differences between the precocious puberty group and the Orexin-A+OX1R antagonist group(P＞0.05). At post puberty stage, the leptin level in the Orexin-A group was lower than that in the precocious puberty group(t=3.674,P＜0.05). Conclusion Orexin-A can inhibit the initiation and progress of the HPGA by inhibiting Kisspeptin expression in the hypothalamus. Energy metabolism is related to the initiation of HPGA.

Key words: precocious puberty, orexin-A, leptin, kisspeptin, energy metabolism

摘要： 目的观察食欲素-A(Orexin-A)对大鼠性发育和血清黄体生成素(LH)、卵泡刺激素(FSH)、雌二醇(E2)、瘦素(Leptin)、吻肽(Kisspeptin)水平的影响,探讨能量代谢在下丘脑-垂体-性腺轴(HPGA)启动中的作用。方法 2018年6月将100只5日龄的SPF级SD仔鼠随机分成4组(每组25只):对照组,性早熟组,Orexin-A组,Orexin-A+食欲素受体1(OX1R)拮抗剂组。后三组皮下注射25μl的含达那唑(300μg/只)的乙醇与乙二醇的混合液1次,建立大鼠性早熟模型。对照组注射同体积的不含达那唑的乙醇与乙二醇的混合液1次。15日龄后,Orexin-A组、Orexin-A+OX1R拮抗剂组分别每天侧脑室注射1次0.5 nmol/L的Orexin-A 5μl和同浓度的Orexin-A 5 μl+30 nmol/L的OX1R拮抗剂5 μl。比较各组大鼠首次阴道开口时间和青春前期、青春期及青春后期3个时间段的血清性激素、Kisspeptin、Leptin水平。结果 1)性早熟组大鼠首次阴道开口时间明显早于对照组(H＝3.092,P=0.012);2)青春前期:Orexin-A组LH、雌二醇(E2)、Kisspeptin、Leptin水平低于性早熟组(t=-3.082、-2.476、-3.732、-3.289,P＜0.05);而Orexin-A+OX1R拮抗剂组与性早熟组相比较,除Kisspeptin水平差异有统计学意义(t=-4.486,P<0.05),其余各指标组间差异均无统计学意义(P>0.05)。青春期:Orexin-A组LH、Leptin水平低于性早熟组(t=-2.469,H=-2.771,P＜0.05);而Orexin-A+OX1R拮抗剂组与性早熟组相比较,各指标组差异均无统计学意义(P>0.05)。青春后期:Orexin-A组Leptin水平低于性早熟组(t=3.674,P＜0.05)。结论 Orexin-A可能通过抑制下丘脑Kisspeptin的表达来抑制HPGA的启动和进展。能量代谢与HPGA的启动具有相关性。

关键词: 性早熟, 食欲素-A, 瘦素, 吻肽, 能量代谢

CLC Number:

R338

YANG Mei, LI Hai-yan, HOU Hui-dan, HAN Jing, TAO Yue-hong. Role of Orexin-A in the initiation of hypothalamic-pituitary-gonadal axis[J]. Chinese Journal of Child Health Care, 2021, 29(7): 730-733.

杨眉, 李海艳, 侯会丹, 韩敬, 陶月红. 食欲素-A在下丘脑-垂体-性腺轴启动中的作用[J]. 中国儿童保健杂志, 2021, 29(7): 730-733.

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