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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Luteinizing hormone-releasing hormone (LH-RH) antagonist Cetrorelix down-regulates the mRNA expression of pituitary receptors for LH-RH by counteracting the stimulatory effect of endogenous LH-RH
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Luteinizing hormone-releasing hormone (LH-RH) antagonist Cetrorelix down-regulates the mRNA expression of pituitary receptors for LH-RH by counteracting the stimulatory effect of endogenous LH-RH

机译：黄体生成激素释放激素（LH-RH）拮抗剂Cetrorelix通过抵消内源性LH-RH的刺激作用下调LH-RH垂体受体的mRNA表达

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摘要

The mechanisms through which LH-RH antagonists suppress gona- dotroph functions and LH-RH receptor (LH-RH-R) production are incompletely understood. To elucidate these mechanisms. we inves- tigated the effects of Cetrorelix on the mRNA expression of pituitary LH-RH-R and luteinizing hormone (LH) secretion in three experimental systems with different pituitary LH-RH environments. Ovariectomy induced 3.61-fold and 6.34-fold increases in the mRNA expression of pituitary LH-RH-R in rats after 11 and 21 days, respeCtiveIy. Affer (5 h) a single injection of 100 μg Cetrorelix, no significant decrease oc- curred in the mRNA levels of pituitary LH-RH-R in ovariectomized (OVX) rats with high pituitary exposure to LH-RH, but there was a significant 23.2/100 reduction in cycling rats with normal hypophysial LH-RH environment. Prolonged treatment for 10 days with a Cetro- relix depot formulation releasing 100 μg/day decreased the concen- tration of mRNA for pituitary LH-RH-R by 72.6/100 in OVX rats, but only by 32.9/100 in normal rats. The decline in serum LH was 98.7/100 in OVX rats and 63.2/100 in normal rats, resulting in a minimal 0.1-0.2 ng/ml LH concentration in both groups. A continuous exposure of pituitary cells to 100 nM Cetrorelix in the super fusion system. which is devoid of LH-RH. did not cause any significant changes in LH-RH-R mRNA level. These studies demonstrate that prolonged exposure to Cetrorelix in vivo, but not in vivo, down-regulates the mRNA expression of the pituitary receptors for LH-RH. Our findings indicate that LH-RH an- tagonists exert their inhibitory effects on the gene expression of pituitary LH-RH-R by counteracting the stimulatory effect of endog- enous LH-RH.
机译：LH-RH拮抗剂抑制性腺功能和LH-RH受体（LH-RH-R）产生的机制尚不完全清楚。阐明这些机制。我们在三个不同垂体LH-RH环境的实验系统中研究了Cetrorelix对垂体LH-RH-R mRNA表达和促黄体生成激素（LH）分泌的影响。卵巢切除术分别在11和21天后导致大鼠垂体LH-RH-R mRNA表达增加3.61倍和6.34倍。在单次注射100μgCetrorelix后（5小时），在垂体高度暴露于LH-RH的卵巢切除（OVX）大鼠中垂体LH-RH-R的mRNA水平没有显着降低，但有显着降低在正常的体下LH-RH环境中，骑自行车的大鼠减少23.2 / 100。用Cetrorelix制剂延长治疗10天，释放量为100μg/天，在OVX大鼠中垂体LH-RH-R的mRNA浓度降低了72.6 / 100，而在正常大鼠中仅降低了32.9 / 100。 OVX大鼠的血清LH下降为98.7 / 100，正常大鼠的血清LH下降为63.2 / 100，两组的最低LH浓度为0.1-0.2 ng / ml。在超级融合系统中垂体细胞连续暴露于100 nM Cetrorelix中。不含LH-RH。没有引起LH-RH-R mRNA水平的任何显着变化。这些研究表明，在体内而不是在体内长时间暴露于Cetrorelix会下调LH-RH垂体受体的mRNA表达。我们的发现表明，LH-RH拮抗药通过抵消内源性LH-RH的刺激作用而对垂体LH-RH-R的基因表达发挥抑制作用。

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