Abstract

Human chorionic gonadotropin (hCG) and luteinizing hormone (LH) regulate testicular steroidogenesis by interacting with the orthosteric site located in the extracellular domain of the LH receptor (LHR). The use of hCG and LH in medicine is fraught with side effects caused by hyperactivation of LH-dependent cascades and the development of resistance of target cells to endogenous gonadotropins due to a decrease in the activity and expression of LHR. An alternative to gonadotropins is low-molecular-weight compounds which interact with the LHR transmembrane allosteric site. The goal of this work was to study the relationship between the steroidogenic effects of hCG and thieno[2,3-d]pyrimidine derivatives (TPDs) with an activity of LHR agonists and their ability to influence the expression of the LHR-encoding Lhr gene both in vitro, when acting on the primary culture of rat Leydig cells, and in vivo, when administered to male rats. hCG stimulated testosterone production with a high efficiency at an early stage of its effect on Leydig cells (after 30 min) and upon a single administration to male rats (after 3 h), exceeding TPDs in activity by this parameter. After 1–3 h of acting on Leydig cells and long-term administration to male rats, the steroidogenic effect of hCG decreased and became comparable to that of TPDs. In the Leydig cells and rat testes, hCG suppressed Lhr gene expression, which was partially restored in vivo on days 7–10 being accompanied by a slight increase in the steroidogenic effect of hCG, though to a significantly smaller extent than on the first day. The treatment with TP03, which was the most active of the TPDs studied, had a little effect on Lhr gene expression in Leydig cells but significantly increased it in the rat testes after long-term administration of the drug. The steroidogenic effect of TP03 positively correlated with Lhr gene expression. When TP03 was applied to aging rats, its steroidogenic effect decreased, most likely, due to the absence of its stimulatory effect on LHR expression. Thus, after long-term administration, TPDs exert a moderately expressed, stable over time, stimulatory effect on testosterone production but do not decrease LHR expression, which prevents testicular resistance to endogenous gonadotropins under conditions of steroidogenesis stimulation.

中文翻译：

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黄体化激素受体的低分子量变构激动剂对其在大鼠睾丸中表达和分布的影响

摘要

人绒毛膜促性腺激素（hCG）和促黄体生成激素（LH）通过与位于LH受体（LHR）胞外域的正构位点相互作用来调节睾丸类固醇生成。hCG和LH在医学中的使用充满了LH依赖性级联反应的过度激活以及LHR活性和表达降低导致靶细胞对内源性促性腺激素产生抗性所引起的副作用。促性腺激素的替代物是与LHR跨膜变构位点相互作用的低分子量化合物。这项工作的目的是研究hCG和具有LHR激动剂活性的硫代[2,3- d ]嘧啶衍生物（TPDs）的类固醇生成作用与它们影响LHR编码表达的能力之间的关系。当作用于大鼠Leydig细胞的原代培养物时，Lhr基因既在体外，当对雄性大鼠给药时，在体内也是如此。hCG在其对Leydig细胞的作用的早期（30分钟后）和对雄性大鼠单次给药（3小时后）时，高效地刺激了睾丸激素的产生，其活性超过了该参数的TPD。在对Leydig细胞作用1-3小时并长期对雄性大鼠给药后，hCG的类固醇生成作用下降，并变得与TPD相当。在Leydig细胞和大鼠睾丸中，hCG抑制Lhr基因表达，在第7-10天在体内部分恢复，同时伴随着hCG的类固醇生成作用略有增加，尽管程度要比第一天小得多。在研究的TPD中最活跃的TP03处理对Leydig细胞中Lhr基因表达的影响很小，但长期给药后在大鼠睾丸中显着增加了Lhr基因的表达。TP03的类固醇生成作用与Lhr正相关基因表达。当TP03应用于衰老大鼠时，其类固醇生成作用降低的可能性最大，这是由于缺乏对LHR表达的刺激作用。因此，长期给药后，TPD对睾丸激素的产生具有适度表达的，随时间推移稳定的刺激作用，但不会降低LHR的表达，从而防止了在类固醇生成刺激下睾丸对内源性促性腺激素的抵抗。