Changes in numbers of ovarian follicles and coincident secretion of pituitary gonadotropins were characterized in suckled, anovulatory beef cows injected iv with 500 ng of luteinizing hormone-releasing hormone (LHRH) every 2 h for 48 or 96 h, starting 21.4 +_ .4 d after parturition. Two hours after the last injection, all cows were ovariectomized. Compared with saline-injected controls, LHRH ha...

LHRH and its analogues produce profound antireproductive effects in both sexes of a variety of animal species. Although the LHRH agonists induce gonadotropin release, gonadal steroid secretion, ovulation, and spermatogenesis as an expression of their traditional profertility pharmacologic profile, they paradoxically and characteristically cause predominant antifertility effects which have been ...

Sexual development and mature reproductive function are controlled by a handful of neurones that, located in the basal forebrain, produce the decapeptide luteinizing hormone releasing hormone (LHRH). LHRH is released into the portal system that connects the hypothalamus to the pituitary gland and act on the latter to stimulate the synthesis and release of gonadotrophin hormones. The pubertal ac...

The objective was to determine whether the suckling-induced delay in return to estrus postpartum could be explained by changes in hypothalamic LHRH content or ability of the pituitary to release LH and FSH in response to LHRH or 59 mM K+ in vitro. In addition, serum concentrations of several other hormones were measured. Nine Holstein cows were suckled ad libitum by two calves and milked by mac...

The aim of the study was to test serum concentrations of the chosen cytokines in patients with prostate cancer (PCa) treated with an luteinizing hormone-releasing hormone (LHRH) analogue. We tested interleukin (IL)-2, IL-10, tumor necrosis factor (TNF)-alpha, interferon (INF)-gamma in blood at three time points; I - before the injection, II - 10 days and III - 20 days after the injection in 14 ...

The control of M-current by muscarinic ACh receptors and luteinizing hormone releasing hormone (LHRH) receptors was studied in dialyzed frog sympathetic ganglion neurons. M-current was recorded in dialyzed cells without run-down or changes in its biophysical properties and could be reversibly suppressed by muscarine and teleost LHRH (t-LHRH). However, dialysis with internal solutions lacking AT...

Previous in vivo studies have shown that delta 9-tetrahydrocannabinol (THC), the principal active ingredient in marijuana, can suppress both luteinizing hormone (LH) and growth hormone (GH) secretion after its injection into the third ventricle of conscious male rats. The present studies were designed to determine the mechanism of these effects. Various doses of THC were incubated with either s...

Nitric oxide (NO) affects reproductive processes both at the level of the brain and reproductive tract and this review is focused on its role as an essential regulator of the hypothalamic control of reproduction. The data gathered indicate that glutamate stimulates noradrenergic neurons which subsequently activate NO-ergic cells via alpha1-adrenergic receptors. The released NO diffuses into lut...

The requirements of purified rat Leydig cells for intra- and extra-cellular Ca2+ during steroidogenesis stimulated by LH (lutropin), cyclic AMP analogues and LHRH (luliberin) agonist were investigated. The intracellular Ca2+ concentrations ([Ca2+]i) were measured by using the fluorescent Ca2+ chelator quin-2. The basal [Ca2+]i was found to be 89.4 +/- 16.6 nM (mean +/- S.D., n = 25). LH, 8-brom...