Department of Cell Biology, Physiology and Immunology, University of Córdoba, Avda. Menéndez Pidal s/n., 14004 Córdoba, Spain.
J Physiol Biochem. 2011 Jun;67(2):145-51. doi: 10.1007/s13105-010-0057-z. Epub 2010 Nov 18.
Rat ovaries stimulated with human follicle-stimulating hormone (hFSH) overexpress a factor that attenuates the LH surge in the rat: the putative gonadotropin surge-attenuating factor (GnSAF). A reduced gondadotrope progesterone receptor (PR) phosphorylation/activation is likely to be the main causative factor involved in GnSAF bioactivity on LH release. Besides, GnSAF reduces LH synthesis as well as LH secretion, and it is not known whether PR is involved in the inhibitory action of GnSAF on LH synthesis. Thus, the purpose of the present work was to evaluate the involvement of PR in the inhibitory effects of GnSAF on LH synthesis in cycling rats. To this end we used a specific radioimmunoassay and reverse transcription-polymerase chain reaction (RT-PCR) to study the effect on LH pituitary content and LHβ mRNA expression of PR occupancy with P (3 mg/0.2 ml oil in diestrus) on the inhibitory effects of hFSH (0, 0.1, 1, and 10 IU) in metestrus (day 2) and diestrus (day 3) on LH synthesis on proestrus in intact and on day 4 in day 2 ovariectomized (OVX) rats injected with 5 and 10 μg of estradiol benzoate (EB) on days 2 and 3, respectively. Results showed that (1) hFSH decreased pituitary LH content in intact, but not in OVX rats injected with EB, without affecting LHβ mRNA levels, and (2) PR occupancy with P annulled the inhibitory action of hFSH on pituitary LH content. These results indicate that PR is involved in ovarian GnSAF effect on LH content probably at a post-transcriptional level.
用人类促卵泡激素（hFSH）刺激大鼠卵巢会过度表达一种因子，这种因子可以减弱大鼠的 LH 激增：假定的促性腺激素激增抑制因子（GnSAF）。黄体生成素细胞孕激素受体（PR）磷酸化/激活减少很可能是 GnSAF 对 LH 释放的生物活性所涉及的主要致病因素。此外，GnSAF 减少 LH 的合成和分泌，并且尚不清楚 PR 是否参与 GnSAF 对 LH 合成的抑制作用。因此，本研究的目的是评估 PR 是否参与 GnSAF 对循环大鼠 LH 合成的抑制作用。为此，我们使用特异性放射免疫测定法和逆转录聚合酶链反应（RT-PCR）来研究 PR 占据对 LH 垂体含量的影响以及 PR 占据对 hFSH（动情前期的 0、0.1、1 和 10IU）对 LHβ mRNA 表达的影响，以研究 hFSH 在动情前期（第 2 天）和动情期（第 3 天）对 LH 合成的抑制作用在完整大鼠和在第 2 天卵巢切除（OVX）大鼠上分别在第 2 天和第 3 天注射 5 和 10μg 苯甲酸雌二醇（EB）后的第 4 天。结果表明：（1）hFSH 降低了完整大鼠的垂体 LH 含量，但不影响 OVX 大鼠中注射 EB 的垂体 LH 含量，而不影响 LHβ mRNA 水平，并且（2）PR 占据 P 消除了 hFSH 对垂体 LH 含量的抑制作用。这些结果表明，PR 参与了卵巢 GnSAF 对 LH 含量的作用，可能在转录后水平上。
