Immunization of adult male rabbits with a synthetic luteinizing hormone-receptor peptide (LH-RP; representing amino-acids 21-41 of the extracellular domain of the rat LH receptor) resulted in production of high-titer antibodies capable of interacting with particulate and cell-based LH receptors. The antibody produced was able to inhibit binding of 125I-labeled human chorionic gonadotropin (hCG)...

We have measured the size of the releasable pools of LH and FSH in the pituitary glands of ovariectomized ewes in which the pituitary was isolated surgically from the hypothalamus. The ewes were given GnRH pulses (250 ng) every hour (N = 3) or every 2 h (N = 3) for 1 week and then given a high dose GnRH infusion (0.5 micrograms/min) for 4 h. Blood samples were collected to characterize the LH a...

BACKGROUND High circulating luteinizing hormone (LH) level is a typical biochemical feature of polycystic ovary syndrome (PCOS) whose pathophysiology is still unclear. Certain mutations of LH and LH receptor (LHR) may lead to changes in bioactivity of these hormones. The aim of this study was determine the role of the LH and LHR polymorphisms in the pathogenesis of PCOS using a genetic approach...

Serum LH concentrations were less than 1 ng/ml immediately prior to castration of four 5-month-old Holstein bulls. A significant increase occurred 7 hr post-castration and serum LH remained elevated thereafter, interspersed with non-rhythmic episodic fluctuations of this gonadotropin. Single injections of testosterone or dihydrotestosterone, given iv or im, did not depress post-castration serum...

Although it is well established that the secretory activity of the corpus luteum absolutely depends on the presence of pituitary-derived luteinizing hormone (LH), it is unknown why the life span of the corpus luteum is extended during early pregnancy by the placental production of chorionic gonadotropin (CG) but regresses in the presence of LH despite the fact that CG and LH have similar action...

Gonadotropin-releasing hormone (GnRH) stimulated the formation of two major metabolites of the 5-lipoxygenase pathway, leukotriene (LT) B4 and LTC4, as well as luteinizing hormone (LH) release in primary cultures of rat anterior pituitary cells. Several lines of evidence suggested the presence of a GnRH-dependent pituitary endocrine system in which LTs act as second messengers for LH release: (...

Motilin is secreted in a clear episodic pattern during fasting or during the interdigestive phase, but feeding promptly stops this secretory pattern, and plasma concentrations of motilin decrease. We have previously determined that fasting markedly suppresses pulsatile luteinizing hormone (LH) secretion in female rats in the presence of oestrogen. In the present study, we wished to learn if mot...

Luteinizing hormone (LH) is one of the main pituitary hormones that regulate ovulation, however its role has not been studied in giant panda. In this study, we developed an ELISA method for the detection of panda urinary LH. We analyzed urinary hormones of 24 female pandas during 36 breeding periods, we found females could easily be impregnated if the first mating occurred within 10 hours after...

The effects of various chemical and enzymatic treatments on the biological activity of porcine luteinizing hormone-releasing hormone (LH-RH) are described. This experiment was performed before the elucidation of the structure of LH-RH. LH-RH activity was abolished by the following endopeptidases: chymotrypsin, subtilisin, papain, and thermolysin, but not by pepsin or trypsin. Exopeptidases d...

The process of luteinization, during which granulosa cells are transformed into luteal cells, is accompanied by dramatic changes in the response of luteal cells to LH. Although luteal cells require LH-cAMP signalling cascade for survival, whether these cells respond to trophic factors through changes in gene expression remains poorly characterized. In an attempt to characterize gonadotrophin (L...