Expression of estrogen receptor-α and cFos in norepinephrine and epinephrine neurons of young and middle-aged rats during the steroid-induced luteinizing hormone surge
Expression of estrogen receptor-α and cFos in norepinephrine and epinephrine neurons of young and middle-aged rats during the steroid-induced luteinizing hormone surge
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DOI：
10.1210/en.2002-220430
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发表时间：
2002-10-01
期刊：
影响因子：
4.8
通讯作者：
Jennes, L
中科院分区：
文献类型：
--
作者：
Temel, S;Lin, W;Jennes, L
去甲肾上腺素（NE）和肾上腺素是雌性大鼠排卵期促性腺激素（GnRH）释放的重要刺激物。先前的研究表明，中年大鼠的儿茶酚胺能神经元对雌二醇敏感，下丘脑的NE释放减少，此时发情周期变得不规则，后来不再存在。本研究的目的是确定中年大鼠的NE和肾上腺素神经元是否继续表达雌激素受体(ER)- α；雌激素受体α和cfo的时间表达随年龄的变化而变化；脑干儿茶酚胺能神经元中酪氨酸羟化酶（TH）、多巴胺- β羟化酶（DBH）和苯乙醇- n -甲基转移酶mRNA含量随年龄的增加而变化。结果表明：两组间TH mRNA含量无显著差异；然而，在中年动物的A1、A2和C1区DBH mRNA水平在激增期间没有像在年轻动物中观察到的那样上升。尽管在年轻和中年动物中表达ER-a的NE和肾上腺素神经元的比例在激增期间没有变化，但中年动物A1和A2区cFos的表达增强，而在年轻动物中则没有。结果表明，中年大鼠的NE和肾上腺素神经元继续表达适当的基础水平的TH、DBH和苯乙醇- n -甲基转移酶mrna以及ER-a和cFos；然而，在类固醇诱导的激素激增期间，幼龄动物中DBH表达的增强在中年动物中未被发现。另一方面，中年大鼠A1和A2区的cFos表达在峰值期间较高。由此得出结论，在中年大鼠中，激增期间儿茶酚胺释放的减少部分是由于NE神经元对雌二醇的敏感性改变引起的，这导致了cFos的异常表达，而可能不是由于递质合成酶或类固醇受体表达的主要缺陷。
Norepinephrine (NE) and epinephrine are important stimulators of GnRH release during the preovulatory surge in female rats. Previous studies have shown that the catecholaminergic neurons are sensitive to estradiol and that NE release in the hypothalamus is decreased in middle-aged rats at the time when the estrous cycles become irregular and later cease to exist. The aims of the present study were to determine whether the NE and epinephrine neurons continue to express estrogen receptor (ER)-alpha in middle-aged rats; temporal expression of ER-alpha and cFos changes with age during the steroid-induced surge; and tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and phenylethanol-N-methyltransferase mRNA content in catecholaminergic neurons of the brain stem changes during the surge with age. The results show that there was no difference in TH mRNA content; however, DBH mRNA levels in areas A1, A2, and C1 of the middle-aged animals did not rise during the surge as was observed in the young animals. Although the percentage of NE and epinephrine neurons that express ER-a was unchanged during the surge in both young and middle-aged animals, cFos expression was enhanced in areas A1 and A2 of the middle-aged animals but not in the young animals. Together the results suggest that NE and epinephrine neurons in the middle-aged rat continue to express appropriate basal levels of TH, DBH, and phenylethanol-N-methyltransferase mRNAs as well as ER-a and cFos; however, the enhancement of DBH expression, as seen in the young animals during the steroid-induced surge, was not detected in middle-aged animals. On the other hand, cFos expression in the middle-aged rat was higher in areas A1 and A2 during the surge. It is concluded that the reduced catecholamine release during the surge in middle-aged rats is caused, in part, by an altered sensitivity of the NE neurons to estradiol, which results in an aberrant cFos expression and probably not by major deficits in the expression of transmitter synthesizing enzymes or steroid receptors.