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Sex difference in the GABAergic control of gonadotropin release in rats

大鼠促性腺激素释放的 GABA 能控制的性别差异

基本信息

批准号：
15590212
负责人：
MITSUSHIMA Dai
金额：
$ 2.37万
依托单位：
Yokohama City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

GABA is a potent regulator of gonadotropin release in both sexes of rats. Using in vivo microdialysis techniques, we examined 24-hour profiles of GABA release in the medial preoptic area (MPO) where gonadotropin-releasing hormone (GnRH) surge generator resides in female rats. Dialysates were collected at 1-h intervals and sequential blood samples (150μl each) were simultaneously collected under freely moving conditions. The GABA release in the MPO of intact rats showed a marked sexual dimorphism. In male rats, the GABA release is episodic without any daily changes. In female rats, the GABA release showed estrous cycle-dependent changes; it is low at estrus and diestrus 1, increases from the late night of diestrus 2 through the early morning of proestrus, and then rapidly decreases until the afternoon of the day of proestrus followed by the preovulatory luteinizing hormone surge. To further determine the sexual dimorphism of the GABA release, GABA release in the MPO was determined in gonadectomized male and female rats 3 - 5 days after estrogen or cholesterol priming. No sex difference in the serum estradiol concentration was observed in estrogen-primed gonadectomized rats. In ovariectomized estrogen-primed rats, the GABA release was high early in the morning, but clearly declined until the afternoon, when it leveled off. A daily surge-like secretion of luteinizing hormone followed in the afternoon. Conversely, in orchidectomized estrogen-primed rats, the GABA release was high without any daily changes. Ovariectomized or orchiectomized cholesterol-primed rats showed low GABA release and high serum luteinizing hormone concentration without any daily changes. These sexually dimorphic effects of estrogen on the GABA release in the MPO as well as the sexually dimorphic GABA release may contribute to the marked sexual dimorphism of gonadotropin release in rats.

GABA是两性大鼠促性腺激素释放的有效调节剂。利用体内微透析技术，我们研究了24小时的档案GABA释放的内侧视前区（MPO）的促性腺激素释放激素（GnRH）浪涌发生器驻留在雌性大鼠。每隔1小时采集一次透析液，并在自由移动条件下同时采集连续血样（每份150μl）。正常大鼠MPO内GABA的释放呈明显的性二型性。在雄性大鼠中，GABA的释放是间歇性的，没有任何每日变化。在雌性大鼠中，GABA的释放表现出发情周期依赖性变化;在发情期和间情期1时较低，从间情期2的深夜到发情前期的清晨增加，然后迅速减少，直到发情前期当天下午，随后是排卵前促黄体生成激素激增。为了进一步确定GABA释放的性二态性，在雌激素或胆固醇引发后3 - 5天，在性腺切除的雄性和雌性大鼠中测定MPO中的GABA释放。在雌激素致敏的性腺切除大鼠中，未观察到血清雌二醇浓度的性别差异。在卵巢切除雌激素引发的大鼠中，GABA的释放在清晨很高，但明显下降，直到下午，当它趋于平稳。每天下午，黄体生成素分泌激增。相反，在去卵巢雌激素致敏的大鼠中，GABA的释放很高，没有任何每日变化。卵巢切除或睾丸切除的胆固醇致敏大鼠表现出低GABA释放和高血清促黄体激素浓度，没有任何每日变化。雌激素对MPO中GABA释放的这些性二态效应以及性二态GABA释放可能导致大鼠促性腺激素释放的显著性二态性。