This study investigated the effects of physiological concentrations of GnRH and estradiol (E2) on LH biosynthesis and release using cultured anterior pituitary cells. Pituitaries from female rats were enzymatically dispersed and cultured for 48 h in steroid-free alpha-Modified Eagle's Medium, followed by a 24-h culture in medium with or without E2. The cells were then incubated for a 4-h (Exp 1 and 2) or 8-h (Exp 3) period in medium containing radiolabeled precursors with or without GnRH. Radioactive precursor incorporation into LH was determined by immunoprecipitation, while immunoreactive LH (iLH) content was quantified by RIA. In the first experiment, all concentrations of E2 (10(-11)-10(-8) M) enhanced iLH release in response to 1 nM GnRH, confirming previous reports. GnRH increased [3H]glucosamine (3H-Gln) incorporation into LH, but had no effect on [35S]methionine (35S-Met) incorporation. The higher concentrations of E2 enhanced GnRH-stimulated 3H-Gln LH production. In the second experiment, the effects of GnRH (10(-9) M) and E2 (5 X 10(-10) M) on the incorporation of [3H]galactose, [3H]mannose, [3H]fucose, or [35S]sulfate into LH were investigated. Although all precursors were incorporated into LH, no specific effect of GnRH and/or E2 on incorporation of any of the precursors into LH was noted. In Exp 3, pituitary cells were cultured with or without 0.5 nM E2 followed by an 8-h incubation with varying physiological concentrations of GnRH (10(-11)-10(-9) M) and radiolabeled precursors (3H-Gln and 35S-Met). GnRH stimulated iLH release in a dose-dependent manner, and this response was enhanced by E2. GnRH also increased the incorporation of both 3H-Gln and 35S-Met into LH, but the dose of GnRH required for this response was dependent upon the estrogen environment. In the absence of E2, only 10(-9) M GnRH increased 3H-Gln LH and 35S-Met LH production, whereas in cells exposed to E2, all concentrations of GnRH (10(-11)-10(-9) M) increased 3H-Gln LH and 35S-Met LH production. In all experiments, the specific activity of radiolabeled LH released under basal conditions was greatly reduced by stimulation with GnRH. These results suggest that GnRH regulates both LH glycosylation and LH polypeptide synthesis and that E2 lowers the physiological concentration of GnRH necessary to stimulate this biosynthetic response. Moreover, estrogen's enhancement of GnRH-stimulated LH release appears to be due to its action on mechanisms regulating the release of previously synthesized stored hormone as well as the release of newly synthesized LH.

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We have analysed the use of a programmed cycle of administration of exogenous steroids without prior suppression with a gonadotrophin-releasing hormone agonist (GnRHa) for the transfer of cryopreserved-thawed pre-embryos. From July 1992 to June 1994, 199 cycles (162 patients) were studied. Pre-embryos had been previously cryopreserved at the pronuclear stage using 1.5 M 1,2-propanediol as a cryoprotectant. Preparation of the endometrium was achieved in a step-up regime with transdermal oestradiol patches (0.1 to 0.4 mg). Progesterone in oil (50 mg i.m.) was started on cycle day 13. Pre-embryos were thawed on day 14 and transferred on day 15 after evidence of survival and cleavage. The mean (+/- SD) age of patients undergoing transfer was 35.4 +/- 4.3 years. The mean number of pre-embryos thawed was 4.7 +/- 1.8 with a mean of 3.3 +/- 1.4 pre-embryos being transferred. Eight of the cycles demonstrated follicular development >16 mm prior to thaw and transfer; however, these patients did not demonstrate a luteinizing hormone surge. Mean endometrial thickness on day 13 was 10.8 +/- 2.1 mm. Overall pregnancy rate was 29.2% (57/195). The ongoing or delivery rate was 16.1% (32/195). The rate of preclinical losses per transfer was 6.2% (12/195). Overall, the implantation rate was 6.2% (47/757). Thus, the use of a programmed cycle for cryopreserved embryo transfer yields favourable pregnancy outcome and offers practical advantages to patients. Prior suppression with a GnRHa is not necessary for endometrial preparation.

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. The patients were preferentially treated with ovulation induction with gonadotropins. With the addition ofgonadotropin stimulation, the total and term pregnancy rates per cycle were 14% and 1 1%, respectively, includingalletiologicfactors. These rates were improvedoverthe3%and 2.6%ratesreported inour previousstudy inwhichovarianstirnulationwasnotgenerallyused. Inniale factor patients, the term pregnancy rate was 9%, higher than the 4% term pregnancy rate reported in our previous study. In the present series, morphology was the only severely impaired parameter. The term pregnancy rate was 1 1 % for patients with ovulatory dysfunction, 10% for those with cervical factor, and 10.5% for those with unexplained infertility.