OBJECTIVE The purpose of this work was to study the direct effect of leptin on LH release by anterior pituitary glands from female rats at the time of spontaneous and steroid-induced LH surge. METHODS LH responsiveness to leptin by pituitaries from rats killed in the afternoon (1500 h) at different stages of the 4-day estrous cycle (diestrus-1: D1; diestrus-2: D2; proestrus; estrus), ovariect...

longer half-life [ 24 h versus 60 min for LH (Yen et al., A new treatment option for patients undergoing ovarian 1968; Damewood et al., 1989)], HCG administration results stimulation is the gonadotrophin-releasing hormone in a prolonged luteotrophic effect, characterized by the develop(GnRH) antagonist protocol, with the possibility to trigger ment of multiple corpora lutea and supraphysiologic...

Administration of human FSH (hFSH) to cyclic rats during the dioestrous phase attenuates progesterone receptor (PR)-dependent events of the preovulatory LH surge in pro-oestrus. The increased bioactivity of the putative ovarian gonadotropin surge inhibiting/attenuating factor induced by hFSH treatment is not associated with a decrease in PR protein expression, and the possibility of its associa...

Plasma levels of LH and FSH before and after ovulation were measured in two rabbit strains (New Zealand A 1077 and Californian A 1066) having a different number of ovulations and rate of embryonic loss. Maximal concentrations and total secreted amounts before ovulation were slightly higher in New Zealand, but the difference was not significant. No relationship between the number of ovulations a...

Background: To assess the usefulness of premature luteinization hormone (LH) surge prevention in an intrauterine insemination (IUI) cycle by GnRH antagonist administration. Materials and Methods: Sixty patients with unexplained or mild male infertility or minimal to mild endometriosis were enrolled in this prospective randomized controlled trial. There were twenty patients in group A (with GnRH...

The role of prostaglandin in reproductive physiology is reviewed with particular emphasis on their possible importance in ovulation in humans. A possible interaction between gonadal steroids, biogenic amines and prostaglandin at hypothalamic-pituitary level, in relation to the release of luteinizing hormone releasing factor, and LH release are noted, and it is suggested that high oestrogen leve...

Successfully using artificial insemination (AI) is defined as getting cows pregnant when the farmer wants them in-calf and making the best use of appropriate genetic potential. Over the past 30 to 50 years, the percentage of animals in oestrus that stand-to-be-mounted (STBM) has declined from 80% to 50%, and the duration of STBM from 15 h to 5 h; both in parallel with a reduction in first-servi...

Recently GnRH antagonist protocols for the prevention of a premature LH surge were introduced, allowing final oocyte maturation to be triggered with a single bolus of a GnRH agonist (GnRHa). GnRHa is as effective as hCG for the induction of ovulation, and apart from the LH surge a FSH surge is also induced. Until recently, prospective randomized studies reported a poor clinical outcome when GnR...