Trisomy 21 is associated with high maternal serum concentrations of intact human chorionic gonadotrophin alpha(HCG) and free beta-HCG whereas these concentrations are markedly decreased in trisomy 18. In this study, we investigated the effect of trisomy 21 and 18 on endogenous HCG concentrations and luteinizing hormone (LH)/HCG receptor expression in placental villous tissue in eight trisomy 21...

Testosterone (Te) concentrations fall gradually in healthy aging men. Postulated mechanisms include relative failure of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and/or gonadal Te secretion. Available methods to test Leydig cell Te production include pharmacological stimulation with human chorionic gonadotropin (hCG). We reasoned that physiological lutropic signaling coul...

Direct sampling of the human spermatic veins has disclosed concomitant LH and testosterone (T) pulses, suggesting pulsatile LH concentration-dependent stimulation of T secretion. However, studies to date have examined this hypothesis using only pharmacological stimulation with hCG. The present study tests the hypothesis that age is marked by decreased T secretory responses to repeated near-phys...

We examined the immunohistochemical localization of luteinizing hormone (LH)/human chorionic gonadotrophin (HCG) receptor (LH-R) in the human ovary using the anti-human LH-R monoclonal antibody, 3B5. In the antral follicles, LH-R was detected on theca interna cells. In pre-ovulatory follicles, granulosa cells also expressed LH-R. During corpus luteum formation, granulosa cells seemed to increas...

It is well established that the luteinizing hormone surge triggers ovulation, a dynamic process leading to the release of the mature oocyte from the ovarian follicle. But how this process controlled by LH signaling remains largely unknown in non-mammalian species. In this study, we investigated the roles of nuclear progesterone receptor (npr) in LH-induced ovulation. Our results indicate that t...

LH and FSH play critical roles in mammalian reproduction by mediating steroidogenesis and gametogenesis in the gonad. Gonadal steroid hormone feedback to the hypothalamus and pituitary influences production of the gonadotropins. We previously demonstrated that progesterone differentially regulates the expression of the LH and FSH -subunits at the level of the gonadotrope: FSH transcription is i...

The selectivity of ligands specific for certain cells can be used to preferentially target chemotherapeutic compounds to neoplastic cells. Human breast, ovarian, endometrial, and prostatic cancers express receptors that can mediate the delivery of targeted cytotoxic compounds to neoplastic cells. Recently, a potent derivative of 2-pyrrolinodoxorubicin (AN-201) conjugated to [D-Lys6] luteinizing...

Human chorionic gonadotropin (hCG) has been used as a surrogate for the mid-cycle LH surge for several decades. Due to structural and biological similarities with LH, hCG binds to and activates the same receptor - the LH/hCG receptor. However, despite the fact that hCG effectively secures final oocyte maturation and ovulation, its use as a surrogate for LH has got several drawbacks - first and ...

The objective of this work was to elucidate the gene expression profiles of luteinizing hormone (LH), prolactin (PRL) and their receptors during the developmental and egg laying stage. The expression of genes encoding pituitary LH and PRL, as well as those for the ovarian LH receptor (LHR) and PRL receptor (PRLR), was determined by quantitative real-time PCR in Zi geese on day 1 and at 1, 2, 3,...

Leydig cells isolated from the testes of rats treated with intravenous exogenous gonadotropin (hCG) or subcutaneous gonadotropin-releasing hormone (GnRH) show markedly decreased luteinizing hormone (LH) receptors and a partial block in testicular 17,20 desmolase activity. In contrast, Leydig cells from animals with equivalent degrees of LH receptor loss induced by subcutaneous hCG treatment sho...