ESTROGEN UP REGULATES TYROSINE HYDROXYLASE GENE IN MONKEY BRAINSTEM

我们之前已经证明，在完整的骑行猕猴中， 排卵前雌激素在30小时内激增，随后是大量 促性腺激素释放激素(GnRH) 下丘脑和来自脑下垂体的黄体生成素(LH)。另外， 外源性雌激素对去卵巢(OVX)猴的影响 排卵前的促黄体生成素激增，伴随着显著的升高 在下丘脑释放去甲肾上腺素(NE)。我们假设 脑干神经元排卵前去甲肾上腺素的释放是由 卵巢雌激素的持续分泌。增加的NE，反过来， 触发促性腺激素释放激素，刺激促黄体生成素释放。为了测试 在这一假设下，我们对酪氨酸羟化酶的mRNA水平进行了量化 (TH，NE合成的限速酶)在蓝斑 (LC，NE细胞体所在的脑干区) 接受雌激素水平治疗的猴子会产生促黄体生成素 涌动。将这些结果与OVX动物进行了比较， 雌激素(n=5)或低雌激素环境(n=5) 诱导黄体生成素激增。用原位杂交技术对TH基因进行定量 多聚甲醛处理后LC薄片的原位杂交 定格。克隆了恒河猴特异的TH基因片段 用作探头。TH基因的表达增加了15倍 雌激素促黄体生成素方案治疗去卵巢猕猴LC 与两个对照组比较。结果表明， LC中TH转录和翻译的增加是一个整体 去甲肾上腺素/促性腺激素释放激素/促黄体生成素的部分排卵前神经内分泌事件 放手。检测基因表达的实验正在进行中。 神经肽Y(NPY)和去甲肾上腺素转运体(NET)在这些动物中的表达。 NPY和Net在LC中与NE细胞共定位，并已知 影响GnRH的分泌，无论是单独的还是在 与东北方向连接。这些研究的结果将加强 了解雌激素在大脑中如何以及在哪里触发 灵长类动物的排卵。

We have previously shown that in intact cycling rhesus monkeys, the surge in preovulatory estrogen is followed within 30 h by massive releases of gonadotropin-releasing hormone (GnRH) from the hypothalamus and luteinizing hormone (LH) from the pituitary. Also, exogenous estrogen treatment in ovariectomized (OVX) monkeys induces a preovulatory-like LH surge that is accompanied by a dramatic increase in hypothalamic release of norepinephrine (NE). We hypothesize that preovulatory release of NE from brainstem neurons is initiated by a sustained secretion of ovarian estrogen. The increased NE, in turn, triggers the release of GnRH which stimulates the LH surge. To test this hypothesis, we quantitated mRNA levels of tyrosine hydroxylase (TH, the rate-limiting enzyme of NE synthesis) in the locus coeruleus (LC, a brainstem area where NE cell bodies are located) of 5 OVX monkeys treated with a level of estrogen that is known to induce a LH surge. These results were compared with OVX animals either without estrogen (n = 5) or with a low estrogen milieu (n = 5) that does not induce a LH surge. Quantification of TH mRNA was carried out by in situ hybridization in thin sections of the LC after paraformaldehyde fixation. A rhesus monkey-specific TH cDNA fragment was cloned for use as a probe. A 15-fold increase occurred in TH gene expression in the LC of OVX monkeys treated with the LH-inducing regimen of estrogen as compared to the two control groups. The results suggest that an increase in TH transcription and translation in the LC is an integral part of the preovulatory neuroendocrine events surrounding NE/GnRH/LH release. Experiments are in progress to examine the gene expression of neuropeptide Y (NPY) and NE transporter (NET) in these animals. Both NPY and NET are colocalized with NE cells in the LC and are known to influence the secretion of GnRH, either individually or in conjunction with NE. The findings of these studies will enhance the understanding of how and where estrogen acts in the brain to trigger ovulation in the primate.