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PubMedDate not supplied

Induction of ovulation after gnRH antagonists.

The gonadotrophin-releasing hormone (GnRH) antagonist binds competitively to the receptors and thereby prevents endogenous GnRH from exerting its stimulatory effect on the pituitary cells. This causes suppression of gonadotrophin secretion which occurs immediately after administration of the antagonist. When using GnRH antagonist in controlled ovarian stimulation, ovulation or maturation of the oocyte can, therefore, be induced by a variety of drugs, e.g. native GnRH, recombinant LH or short-acting GnRH agonists. Short-acting GnRH agonists were recommended for triggering ovulation in cases with a high risk of developing ovarian hyperstimulation syndrome (OHSS). Since it is evident that GnRH is required to initiate the LH surge and the oestradiol rise, a single administration of GnRH antagonist during the late follicular phase delays the LH surge. Studies showed that a single s.c. administration of 3 or 5 mg of Cetrorelix in the late follicular stage was sufficient to prevent the LH surge for 617 days. This phenomenon can be used in high responder patients who are prone to OHSS. The question whether this delay has any effect on oocyte quality and maturation still remains unanswered. Overall, there are four uses for GnRH antagonist: (i) using short-acting GnRH agonists for triggering ovulation in cases in which the GnRH antagonist is part of the protocol for ovarian stimulation. Recombinant LH and native LHRH could also be used as triggers of LH surge; (ii) delaying the LH surge in cases prone to OHSS by treatment with GnRH antagonist; (iii) to administer GnRH antagonist during the luteal phase to decrease the activity of corpora lutea; (iv) in polycystic ovarian disease with elevated LH the LH/FSH ratio can be corrected with the injection of GnRH antagonist prior to and during ovarian stimulation.

Female↗
PubMed1996

Comparison of gonadotrophin-releasing hormone analogues and human chorionic gonadotrophin for the induction of ovulation and prevention of ovarian hyperstimulation syndrome: a case-control study.

Gonadotrophin-releasing hormone analogue (GnRHa) has been suggested as an alternative to human chorionic gonadotrophin (HCG) for triggering ovulation, while preventing ovarian hyperstimulation syndrome (OHSS). Since a prospective, controlled study would be unethical at this point, we used a retrospective, case-self control approach to compare GnRHa with HCG in that context. A group of 16 in-vitro fertilization (IVF) patients who had severe OHSS in previous cycles, in which HCG was given to trigger ovulation, were studied in subsequent cycles in which GnRHa was used. Each GnRHa cycle (case) was compared to a previous HCG cycle that resulted in OHSS (self control). None of these subsequent cycles resulted in severe OHSS. The use of GnRHa did not affect the number of oocytes retrieved or their quality. Serum oestradiol concentrations on the day of ovulation triggering were significantly (P < 0.01) higher in the GnRHa cycles compared to HCG cycles. Exogenous progesterone and oestradiol were effective in maintaining relatively constant serum oestradiol and progesterone serum concentrations during the luteal phase. Pregnancy rate per cycle was similar in the two groups. In conclusion, the use of GnRHa to induce ovulation in IVF patients, who are at high risk for developing OHSS, effectively eliminates this risk without affecting other parameters of the stimulation cycle.

Case-Control Studies↗
PubMed1991

Low-dose gonadotrophin therapy for induction of ovulation in 100 women with polycystic ovary syndrome.

Women with anovulation due to polycystic ovary syndrome are likely to develop multiple follicles during gonadotrophin therapy and therefore have a high risk of multiple pregnancy. We have developed a low-dose regimen for use in these women; 100 women with clomiphene-resistant polycystic ovary syndrome were treated. Ninety-five of the women ovulated at least once, 72% of the 401 cycles induced were ovulatory and the majority (73%) of these were uni-ovulatory. The overall cumulative conception rate was 55% at 6 months with only two multiple pregnancies. The rate of early pregnancy loss was 32%, which is similar to that reported by other groups. The prevalence of complications was low with no cases of severe hyperstimulation and less than 5% of cycles were abandoned because of development of multiple follicles. Analysis of baseline and mid-follicular luteinizing hormone levels showed that a raised baseline and/or mid-follicular luteinizing hormone level was associated with a poor response to treatment, i.e. anovulation, ovulation but no conception, or early pregnancy loss. There were no successful pregnancies in the women whose luteinizing hormone levels were persistently raised during ovulatory cycles. Low-dose gonadotrophin therapy is a safe and effective method of inducing ovulation; it is associated with a high incidence of single follicular development and a very low multiple pregnancy rate.

Clomiphene↗
PubMed1993

The induction of ovulation with pulsatile gonadotrophin-releasing hormone (GnRH) administration in hyperandrogenic women after down-regulation with buserelin or suppression with an oral contraceptive.

The hypothalamic-pituitary axis of 22 hyperandrogenic infertile women had suppression with either the gonadotrophin-releasing hormone (GnRH)-analogue buserelin (n = 12) or with an oestrogen-gestagen compound (Diane; n = 12). This was followed by pulsatile GnRH application for inducing ovulation (Zyklomat). In terms of ovulation and pregnancy rates the buserelin pre-treatment was more effective than the steroid pre-treatment, especially in hyperandrogenic non-polycystic ovaries (PCO).

Adult↗
PubMed1993

Treatment with naltrexone in hypothalamic ovarian failure: induction of ovulation and pregnancy.

Sixty-six women suffering from various grades of hypothalamic ovarian failure were treated with the opiate antagonist naltrexone at doses ranging from 25 to 150 mg per day. This treatment resulted in complete normalization of the menstrual cycle in 49 of 66 patients, as indicated by the pattern of circulating levels of gonadotrophins and ovarian steroids. Five patients failed to respond, three of whom were suffering from primary hypothalamic amenorrhoea. In patients who responded to the administration of naltrexone, there was a dramatic increase in the amplitude and frequency of gonadotrophin pulses, reflecting disinhibition of the hypothalamic gonadotrophin-releasing hormone (GnRH) pulse generator. Eighteen pregnancies were achieved in 16 women who were also treated for infertility, resulting in a cumulative pregnancy rate closely resembling that of a normal population. There were only minor side-effects that could be attributed to the drug. These data demonstrate that chronic administration of an opiate antagonist will normalize ovarian function in women suffering from different grades of hypothalamic ovarian failure. The data therefore support the view that suppression of the activity of the hypothalamic pulse generator, that directs GnRH release, is mediated by endogenous opioids. Also, that hypothalamic ovarian failure is the consequence of an inappropriate increase in opioid tone impinging on neurons that release GnRH in a pulsatile manner into the pituitary portal circulation.

Adolescent↗
PubMed1994

Induction of ovulation in rabbits by pure urinary luteinizing hormone.

In 18-week-old nulliparous rabbit does, ovulation was induced with 50 IU of pure urinary luteinizing hormone (LH; LH group), or 50 IU of human chorionic gonadotrophin (HCG; HCG group), in order to determine the effect of these treatments on 17 beta-oestradiol and progesterone concentrations, and on oocyte and embryo quality. Luteinizing follicles, recovered oocytes, progesterone concentration and grade 5 embryos were significantly reduced when pure urinary LH was used. Statistically significant correlations were found: (i) between oestradiol concentration and number of degenerated oocytes in both groups (positive); (ii) between oestradiol concentration and grade 1 and 2 embryos (negative), and grade 5 embryos (positive) in the HCG group; (iii) between progesterone concentration and metaphase II oocytes (negative), and between progesterone and grade 5 embryos (positive), in the HCG group; and (iv) between progesterone and oestradiol concentrations (negative) in the LH group. It seems that the oestradiol to progesterone ratio improves during the early luteal phase when ovulation is induced with LH, and that oestradiol and progesterone concentrations could play a role in determining oocyte and embryo quality.

Animals↗
PubMed2005

Conditional induction of ovulation in mice.

Follicle-stimulating hormone controls the maturation of mammalian ovarian follicles. In excess, it can increase ovulation (egg production). Reported here is a transgenic doxycycline-activated switch, tested in mice, that produced more FSHB subunit (therefore more FSH) and increased ovulation by the simple feeding of doxycycline (Dox). The transgenic switch was expressed selectively in pituitary gonadotropes and was designed to enhance normal expression of FSH when exposed to Dox, but to be regulated by all the hormones that normally control FSH production in vivo. Feeding maximally effective levels of Dox increased overall mRNA for FSHB and serum FSH by over half in males, and Dox treatment more than doubled the normal ovulation rate of female mice for up to 10 reproductive cycles. Lower levels of Dox increased the number of developing embryos by 30%. Ovarian structure and function appeared normal. In summary, gene switch technology and normal FSH regulation were combined to effectively enhance ovulation in mice. Theoretically, the same strategy can be used with any genetic switch to increase ovulation (or any highly conserved physiology) in any mammal.

Animals↗
PubMed1984

Perfusion of the rat ovary in vitro: methodology, induction of ovulation, and pattern of steroidogenesis.

A method for perfusion of the rat ovary in vitro for the study of ovulation was developed and characterized. Immature rats (27-29 days old) were primed with 20 IU of pregnant mare's serum gonadotropin (PMSG). Two days later a laparotomy was performed, the aorta and vena cava were cannulated, the right ovary was isolated, and all vessels connecting with the aorta and vena cava except for the right ovarian artery and vein were ligated. The preparation was placed in the perfusion apparatus and perfused for up to 20 h with oxygenated Medium 199 containing 4% bovine serum albumin (37 degrees C, pH 7.4). The perfusion pressure was 70-90 mm Hg and the average flow was 1 ml . min . ovary. Ovulation was confirmed by oocyte recovery from the apparatus. Nine ovaries were perfused without further treatment (controls); only 1 ovulation occurred in this group. Nine ovaries received luteinizing hormone (LH; 0.1 microgram/ml) 1 h after the start of perfusion; 71 ovulations resulted (range, 3-13/ovary). Ovulations did not begin before 9 h after LH administration. Samples of medium were taken frequently for measurement of progesterone, estradiol and androstenedione. Levels of all three steroids rose rapidly and markedly in response to LH but increased only slightly in control perfusions. This study demonstrates that ovulation in the rat ovary can be induced in vitro and provides a basis for further studies on the mechanism of ovulation.

Androstenedione↗
PubMed1992

Induction of ovulation and oocyte maturation of amphibian (Rana dybowskii) ovarian follicles by protein kinase C activation in vitro.

We previously reported that protein kinase C (PKC) activation induced meiotic maturation (germinal vesicle breakdown, GVBD) of Rana dybowskii follicular oocytes cultured in vitro without hormone treatment. The experiments reported here were carried out to establish whether ovarian follicles ovulated in response to PKC activation during culture. A phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), was used for PKC activation. TPA addition (10 microM) to cultured ovarian fragments induced ovulation and maturation of the oocytes similar to that seen following addition of frog pituitary homogenate (FPH, 0.05 pituitary/ml) or progesterone (0.5 microgram/ml). Such changes were not observed when ovarian fragments were treated with inactive phorbol ester. The time course of TPA-induced ovulation was similar to that produced by FPH-stimulated ovulation. Both TPA- and FPH-stimulated ovulation and maturation were blocked by treatment with cycloheximide, forskolin (an adenylate cyclase stimulator), and 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7; a PKC inactivator). FPH treatment markedly increased progesterone levels in the medium during ovarian fragment culture whereas TPA treatment failed to elevate progesterone levels. Thus, TPA treatment mimics FPH and progesterone in inducing ovulation and meiotic maturation in cultured amphibian ovarian fragments. The data strongly suggest that PKC plays an important role in regulating ovulation as well as in modulating amphibian oocyte maturation during follicular differentiation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Hormonal induction of ovulation stimulates atresia of antral follicles in gilts.

Two breeds of prepubertal gilts known to differ in their ovarian development were used to compare the effect of hormonally stimulated ovulation on follicle numbers and proportion of follicular atresia in size classes other than preovulatory follicles. Hormonal treatments (hCG or eCG-hCG) were given to Meishan gilts (n = 36) at 3, 2, and 1 standard deviations (SD) before the mean age of puberty (51, 64, and 77 days of age) and to Large White gilts (n = 24) at 3 and 1 SD before the mean age of puberty (140 and 166 days of age). Ovarian follicle populations determined in the right ovaries 18 h after hCG injection alone (hCG) or 72 h after eCG injection (eCG-hCG) were compared with those in the left ovaries, which had been removed prior to injections. Follicles with dispersed cumulus cells around the oocytes (expected ovulations) observed after hormonal treatments (right ovaries) were considered for follicular measures and categorized into specific size classes according to their diameter. Human CG alone did not affect any follicular parameters measured at any age in either of the two breeds studied. The overall population of nonatretic follicles was significantly reduced by the eCFG-hCG treatment in the Large White breed when imposed at either 3 or 1 SD before the mean age of puberty (262.6 vs. 158.8; p < 0.01). Among the various follicle size classes studied, eCG-hCG treatment significantly decreased the mean number of follicles in size classes 2 (1.13-2.00 mm in diameter) and 3 (2.01-3.56 mm in diameter) at either 3 or 1 SD before the mean age of puberty in the Large White gilts (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Gonadotropin induction of ovulation and corpus luteum formation in young estrogen receptor-alpha knockout mice.

Estrogen receptor-alpha (ERalpha) knockout (ERalphaKO) female mice are infertile. Initially, they exhibit normal follicular development, but by 4-5 wk of age, they begin to develop hemorrhagic ovarian cysts. Follicles in adult ERalphaKO female mice progress to the graafian stage, but there are no corpora lutea (CL). To test whether ERalpha is required for ovarian folliculogenesis, ovulation, and CL formation, eCG and hCG were used to ovulate 3- to 5-wk-old ERalphaKO and wild-type (WT) sibling mice. Gonadotropin administration resulted in ovulation in both ERalphaKO and WT mice. Gonadotropin-treated ERalphaKO females that ovulated produced 7.09 +/- 0.77 oocytes per mouse, whereas gonadotropin-treated WT female mice had 16.17 +/- 0.84 oocytes. Surprisingly, ruptured ERalphaKO ovarian follicles developed into CL that had normal morphology. Gonadotropin-treated ERalphaKO mice had 3-fold higher concentrations of serum progesterone than did control ERalphaKO mice that had been administered saline rather than gonadotropins. Thus, the CL in gonadotropin-treated ERalphaKO mice appeared to be steroidogenically functional. On the basis of these findings, ovarian folliculogenesis, ovulation, and CL formation can occur in the absence of ERalpha, although to a lesser extent than in WT mice.

Animals↗
PubMed1984

The use of pergonal for the induction of ovulation.

With proper patient selection, appropriate pretreatment studies and careful monitoring will ensure that patients ovulate safely. Table 7 is a summary of the results that may be expected following properly monitored hMG therapy. Among estrogen-deficient patients without other causes of infertility, the cumulative pregnancy rate after six cycles will exceed 90%. However, among normoestrogenic patients with no other infertility factors the cumulative conception rate has been reported to be only 50% after 12 courses of therapy, although with the use of ultrasound monitoring it is likely that this latter figure will improve. Nevertheless, these data may be used to afford couples with a realistic prognosis.

Abnormalities, Drug-Induced↗