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Studies on rat ovarian receptors for lutropin (luteinizing hormone). Factors influencing binding and response.

ABSTRACT: The interaction of rat ovarian receptors with lutropin (luteinizing hormone, LH) in vitro was rapid and reversible. The degree of binding was saturable and susceptible to changes in the concentration of lutropin in the medium. The concentration of lutropin receptors in the ovary increases during the natural pubertal period and also in immature rats given pregnant-mare-serum gonadotropin and human choriogonadotropin. In the latter case, the increase in lutropin receptor, after injection of pregnant-mare-serum gonadotropin alone, could be detected only if the ovaries are freed of the bound gonadotropin before exposure to lutropin. The concentration of lutropin receptors was higher in the luteal compartment of the ovary than in the non-luteal parts and increased slightly in aged corpora lutea. Correlation between binding of lutropin to the ovary and the ovarian response to lutropin in terms of cyclic AMP production was found only in prepubertal rat ovaries and in young corpora lutea and not in aged corpora lutea, suggesting the non-equivalence of binding in vitro and ovarian response.

SUBMITTER: Muralidhar K

PROVIDER: S-EPMC1164277 | biostudies-other | 1976 Dec

REPOSITORIES: biostudies-other

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Studies on rat ovarian receptors for lutropin (luteinizing hormone). Applicability of radioimmunoassay to measure lutropin bound to receptors.

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Project description: Not available

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The hormone-binding unit of luteinizing hormone receptor.

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| S-EPMC1153965 | biostudies-other

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MicroRNA expression and regulation in human ovarian carcinoma cells by luteinizing hormone.

Project description:MicroRNAs have been widely-studied with regard to their aberrant expression and high correlation with tumorigenesis and progression in various solid tumors. With the major goal of assessing gonadotropin (luteinizing hormone, LH) contributions to LH receptor (LHR)-positive ovarian cancer cells, we have conducted a genome-wide transcriptomic analysis on human epithelial ovarian cancer cells to identify the microRNA-associated cellular response to LH-mediated activation of LHR.Human ovarian cancer cells (SKOV3) were chosen as negative control (LHR-) and stably transfected to express functional LHR (LHR+), followed by incubation with LH (0-20 h). At different times of LH-mediated activation of LHR the cancer cells were analyzed by a high-density Ovarian Cancer Disease-Specific-Array (DSA, ALMAC™), which profiled ? 100,000 transcripts with ? 400 non-coding microRNAs.In total, 65 microRNAs were identified to exhibit differential expression in either LHR expressing SKOV3 cells or LH-treated cells, a few of which have been found in the genomic fragile regions that are associated with abnormal deletion or amplification in cancer, such as miR-21, miR-101-1, miR-210 and miR-301a. By incorporating the dramatic expression changes observed in mRNAs, strong microRNA/mRNA regulatory pairs were predicted through statistical analyses coupled with collective computational prediction. The role of each microRNA was then determined through a functional analysis based on the highly-confident microRNA/mRNA pairs.The overall impact on the transcriptome-level expression indicates that LH may regulate apoptosis and cell growth of LHR+ SKOV3 cells, particularly by reducing cancer cell proliferation, with some microRNAs involved in regulatory roles.

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Project description:In mammalian ovarian follicles, follicle stimulating hormone (FSH) and luteinizing hormone (LH) signal primarily through the G-protein Gs to elevate cAMP, but both of these hormones can also elevate Ca2+ under some conditions. Here, we investigate FSH- and LH-induced Ca2+ signaling in intact follicles of mice expressing genetically encoded Ca2+ sensors, Twitch-2B and GCaMP6s. At a physiological concentration (1 nM), FSH elevates Ca2+ within the granulosa cells of preantral and antral follicles. The Ca2+ rise begins several minutes after FSH application, peaks at ?10 min, remains above baseline for another ?10 min, and depends on extracellular Ca2+. However, suppression of the FSH-induced Ca2+ increase by reducing extracellular Ca2+ does not inhibit FSH-induced phosphorylation of MAP kinase, estradiol production, or the acquisition of LH responsiveness. Like FSH, LH also increases Ca2+, when applied to preovulatory follicles. At a physiological concentration (10 nM), LH elicits Ca2+ oscillations in a subset of cells in the outer mural granulosa layer. These oscillations continue for at least 6 h and depend on the activity of Gq family G-proteins. Suppression of the oscillations by Gq inhibition does not inhibit meiotic resumption, but does delay the time to 50% ovulation by about 3 h. In summary, both FSH and LH increase Ca2+ in the granulosa cells of intact follicles, but the functions of these Ca2+ rises are only starting to be identified.

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