Increased Fos Immunoreactivity in Suprachiasmatic Nucleus before Luteinizing Hormone Surge in Estrogen-Treated Ovariectomized Female Rats
Increased Fos Immunoreactivity in Suprachiasmatic Nucleus before Luteinizing Hormone Surge in Estrogen-Treated Ovariectomized Female Rats
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DOI：
10.1159/000095341
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发表时间：
2006-10
影响因子：
4.1
通讯作者：
S. Tsukahara
中科院分区：
文献类型：
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作者：
S. Tsukahara
背景/目的：视交叉上核（SCN）被认为控制促黄体激素（LH）激增的时间。本研究旨在研究LH峰期间雌性大鼠SCN（SCNdm和SCNvl）背内侧和腹外侧部分Fos表达的时间模式。还包括检查血浆LH水平的时间变化和前腹侧室周核（AVPV）和促性腺激素释放激素（GnRH）神经元中Fos水平的时间变化。研究方法：注射20 μg苯甲酸雌二醇（EB）或溶剂的卵巢切除大鼠在注射后第2天从Zeitgeber时间（ZT）8：00至16：30 h（ZT 8 -16.5; ZT 0 =开灯; ZT 12 =关灯）的不同时间处死。然后进行Fos和GnRH的免疫组织化学分析和LH的酶联免疫吸附测定。结果：在EB大鼠SCNdm和SCNvl中，Fos免疫反应阳性细胞的数量在ZT 9.5 -10.5和ZT 11 -12之间显著增加。而EB大鼠在ZT 11 -12和ZT 13 -14之间，GnRH神经元和AVPV中LH和Fos水平出现显著峰值。EB组和对照组大鼠在ZT 9.5 -10.5时SCNdm和SCNvl中Fos免疫反应阳性细胞数无显著性差异，而在ZT 11 - 12时SCNdm中Fos免疫反应阳性细胞数显著高于对照组大鼠。总结：这些结果表明，在雌性大鼠LH峰期间，SCN中Fos水平的峰值先于AVPV和GnRH神经元中Fos水平的峰值。
Background/Aims: The suprachiasmatic nucleus (SCN) is thought to control the timing of luteinizing hormone (LH) surges. The present study was designed to examine temporal patterns of Fos expression in the dorsomedial and ventrolateral parts of the SCN (SCNdm and SCNvl) of female rats during an LH surge. It also included examination of temporal changes in plasma LH levels and temporal changes in Fos levels in the anteroventral periventricular nucleus (AVPV) and gonadotropin-releasing hormone (GnRH) neurons. Methods: Ovariectomized rats injected with 20 µg estradiol benzoate (EB) or vehicle were sacrificed at various times from Zeitgeber time (ZT) 8:00 to 16:30 h (ZT8–16.5; ZT0 = lights on; ZT12 = lights off) on the 2nd day after the injection. Immunohistochemical analyses for Fos and GnRH and enzyme-linked immunosorbent assays for LH were then performed. Results: In both the SCNdm and SCNvl of EB rats, the number of Fos-immunoreactive cells significantly increased between ZT9.5–10.5 and ZT11–12. On the other hand, in EB rats there were significant peaks of LH levels and Fos levels in GnRH neurons and the AVPV between ZT11–12 and ZT13–14. There was no significant difference in the number of Fos-immunoreactive cells between EB and control rats in either the SCNdm or SCNvl at ZT9.5–10.5, or in the SCNdm at ZT11–12, whereas the SCNvl of EB rats contained more Fos-immunoreactive cells than that of control rats at ZT11–12. Conclusion: These results suggest that in female rats during an LH surge, a peak in the Fos level in the SCN precedes peaks in Fos levels in the AVPV and GnRH neurons.