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Neural basis for generating gonadotropin-releasing hormone surge

产生促性腺激素释放激素激增的神经基础

基本信息

批准号：
17590209
负责人：
FUNABASHI Toshiya
金额：
$ 2.3万
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：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

The present study investigated the utility of model for in vitro GnRH surge generator by culturing the olfactory placode. We found that model was useful since blockade of cAMP production markedly attunated release of GnRH as did in vivo. In GT1-1 cells, the electrical activity examined by extracellular recording was sometimes related to Ca2+ oscillations. This result suggests that GTI-1 cells are useful as in vitro model for pulse generator. Next, we examined the possible role for glutamatergic neurons generating the surge of GnRH secretion. GluR1-C-tail, a dominant negative mutant of GluR1 (subunit of AMPA receptors), has been shown to act by competing with GluR1 for synaptic delivery during neural plasticity. GluR1-C-tail was expressed in the POA of female rats using lentivirus. Injection with GluR1-C-tail in adult rats had no effect on the surge of LH secretion. When the injection was done at 21-day, the onset of puberty was significantly delayed, by checking viginal opening. After that, the estrous cyclicity was checked by viginal smear and found that the rat injected with GIuR1-C-tail exhibited an irregular estrous cycle. The surge of luteinizing hormone (LH) secretion in the adult rat injected with GluR1-C-tail at 21-day was significantly attenuated, compared to the control rat. The result suggests that GluR1 -mediated plasticity occurs at the time of puberty and is important to maintain surge of LH secretion in adults. We are now examining the trafficking of GluR1 in GnRH neurons by a whole-cell voltage clamp recording. With regard to the role of CREB in the surge generator, we are currently examining the effects of mCREB (dominant negative) or cCREB (constitutively active) on the surge of LH secretion.

本研究通过对嗅觉胎盘的培养，探讨了体外GnRH激波发生器模型的实用性。我们发现这个模型是有用的，因为阻断cAMP的产生显着地调节了GnRH的释放，就像在体内一样。在GT1-1细胞中，细胞外记录检测到的电活动有时与钙振荡有关。这一结果表明，GTI-1细胞可作为脉冲发生器的体外模型。接下来，我们研究了谷氨酸能神经元产生GnRH分泌激增的可能作用。GluR1-C-Tail是GluR1(AMPA受体亚单位)的显性负性突变体，已被证明在神经可塑性过程中与GluR1竞争突触递送。GluR1-C-Tail在慢病毒感染雌性大鼠的视网膜瘤中有表达。成年大鼠注射GluR1-C-Tail对促黄体生成素分泌高峰无影响。当注射在第21天时，通过检查生殖器开放，青春期的开始明显延迟。通过涂片检查动情周期，发现注射GIuR1-C-Tail的大鼠表现出不规则的动情周期。与对照组相比，注射GluR1-C-Tail后21d的成年大鼠黄体生成素(LH)分泌高峰明显减弱。这一结果表明，GluR1介导的可塑性发生在青春期，对维持成人黄体生成素的分泌高峰是重要的。我们现在正在通过全细胞电压钳记录来研究GluR1在GnRH神经元中的转运。关于CREB在浪涌发生器中的作用，我们目前正在研究mCREB(显性负性)或cCREB(结构性活性)对黄体生成素分泌激增的影响。