Pioglitazone improves insulin action and normalizes menstrual cycles in a majority of prenatally androgenized female rhesus monkeys

PURPOSE OF THE STUDY

To determine whether pioglitazone will improve menstrual cyclicity in a fetal programming model for polycystic ovary syndrome.

BASIC PROCEDURES

Eight prenatally androgenized (PA) and 5 control female rhesus monkeys of similar age, body weight and body mass index received an oral placebo daily for 6-7 months followed, after at least 90 days, by daily oral dosing with pioglitazone (3mg/kg) for an additional 6-7 months. Blood was sampled thrice weekly to monitor ovulatory function, and a variety of endocrine challenges were performed to quantify changes in ovarian, gonadotropin and glucoregulatory function.

MOST IMPORTANT FINDINGS

Pioglitazone normalized menstrual cycles in 5 out of 8 (62%) PA females (pioglitazone responsive; Pio(RESP)). Pioglitazone increased serum 17alpha-hydroxyprogesterone responses to an hCG injection in Pio(RESP) PA females, while diminishing serum progesterone, and increasing DHEA and estradiol responses to hCG in Pio(RESP) PA and all normal females.

PRINCIPAL CONCLUSIONS

Insulin resistance plays a mechanistic role in maintaining anovulation in a majority of PA female monkeys.

Effect of chemotherapy on skeletal health in male survivors from testicular cancer and lymphoma

PURPOSE

There are concerns over the late effects of cancer therapy, including accelerated bone loss leading to increased risk of osteoporosis. Treatment-related bone loss is well recognized in breast and prostate cancer, due to overt hypogonadism, but there has been little evaluation of the skeletal effects of chemotherapy alone in adults. This study assesses the extent of bone loss due to previous chemotherapy in men.

EXPERIMENTAL DESIGN

The bone mineral density (BMD) of men who had received previously chemotherapy with curative intent for lymphoma or testicular cancers was compared with that of an age-matched population of men from a cancer control population that had not received chemotherapy. BMD was measured by dual-energy X-ray scanning. Additionally, measurement of sex hormones and the bone turnover markers N-telopeptide fragment of type I collagen and bone-specific alkaline phosphatase were done. All statistical tests were two sided.

RESULTS

One hundred fifteen chemotherapy-treated patients and 102 cancer controls were recruited. There was no statistical difference in BMD between the chemotherapy and control groups at either spine or hip and the mean BMD values in both groups were no lower than that of a reference population. There were no significant differences in estradiol, luteinizing hormone, and testosterone, but follicle-stimulating hormone values were significantly higher in the chemotherapy group (P=0.011). The mean values of NH2-terminal telopeptide fragment of type I collagen and bone-specific alkaline phosphatase were within the reference ranges.

CONCLUSIONS

The absence of accelerated bone loss following chemotherapy is reassuring and suggests that standard dose cytotoxic chemotherapy has no lasting clinically important direct effects on bone metabolism.

Critical role of STAT3 in leptin's metabolic actions

Leptin has pleiotropic effects on glucose homeostasis and feeding behavior. Here, we validate the use of a cell-permeable phosphopeptide that blocks STAT3 activation in vivo. The combination of this biochemical approach with stereotaxic surgical techniques allowed us to pinpoint the contribution of hypothalamic STAT3 to the acute effects of leptin on food intake and glucose homeostasis. Leptin's ability to acutely reduce food intake critically depends on intact STAT3 signaling. Likewise, hypothalamic signaling of leptin through STAT3 is required for the acute effects of leptin on liver glucose fluxes. Lifelong obliteration of STAT3 signaling via the leptin receptor in mice (s/s mice) results in severe hepatic insulin resistance that is comparable to that observed in db/db mice, devoid of leptin receptor signaling. Our results demonstrate that the activation of the hypothalamic STAT3 pathway is an absolute requirement for the effects of leptin on food intake and hepatic glucose metabolism.

Inhibition of prostate carcinogenesis in probasin/SV40 T antigen transgenic rats by leuprorelin, a luteinizing hormone-releasing hormone agonist

The effects of leuprorelin acetate, a luteinizing hormone-releasing hormone agonist (LHRH-A), on prostate carcinogenesis in probasin/SV40 Tag transgenic rat was investigated. Fifteen weeks after administration of 0.28 and 2.8 mg/kg leuprorelin, prostate weights and serum testosterone levels were significantly decreased compared to values for transgenic controls. Histopathological findings revealed that the incidence of prostatic adenocarcinomas was significantly reduced in ventral, dorsal and lateral lobes of the prostate, correlating with decreased expression of SV40 Tag oncoprotein as well as inhibition of DNA synthesis and proliferation of epithelial cells in neoplastic lesions of the ventral prostate. Microarray analysis further showed leuprorelin acetate to significantly inhibit testicular steroidogenesis, suppressing the expression of SV40 Tag oncoprotein and altering the expression of a large number of genes which might be involved in the inhibition of prostate cancer progression in this rat model.

Thiourea-induced thyroid hormone depletion impairs testicular recrudescence in the air-breathing catfish, Clarias gariepinus

We used thiourea-induced thyroid hormone depletion as a strategy to understand the influence of thyroid hormones on testicular recrudescence of the air-breathing catfish, Clarias gariepinus. Treatment with 0.03% thiourea via immersion for 21 days induced hypothyroidism (thyroid hormone depletion) as evidenced by significantly reduced serum T(3) levels. Thiourea-treated males had narrowed seminiferous lobules with fewer spermatozoa in testis, very little or no secretory fluid, reduced protein and sialic acid levels in seminal vesicles when compared to controls. The histological changes were accompanied by reduction in serum and tissue levels of testosterone (T) and 11-ketotestosterone (11-KT), a potent male specific androgen in fish. Qualitative changes in the localization of catfish gonadotropin-releasing hormone (cfGnRH) and luteinizing hormone (LH, heterologous system) revealed a reduction in the distribution of immunoreactive neuronal cells and fibers in thyroid depleted fish. Interestingly, thiourea-withdrawal group showed physiological and histological signs of recovery after 21 days such as reappearance of spermatozoa and partial restoration of 11-KT and T levels. These data demonstrate that thyroid hormones play a significant role in testicular function of catfish. The mechanism of action includes modulating sex steroids either directly or through the hypothalamo (GnRH)-hypophyseal (LH) axis.

Prazosin blocks the glutamatergic effects of N-methyl-D-aspartic acid on lordosis behavior and luteinizing hormone secretion in the estrogen-primed female rat

We have observed that intracerebroventricular (icv) injection of selective N-methyl-D-aspartic acid (NMDA)-type glutamatergic receptor antagonists inhibits lordosis in ovariectomized (OVX), estrogen-primed rats receiving progesterone or luteinizing hormone-releasing hormone (LHRH). When NMDA was injected into OVX estrogen-primed rats, it induced a significant increase in lordosis. The interaction between LHRH and glutamate was previously explored by us and another groups. The noradrenergic systems have a functional role in the regulation of LHRH release. The purpose of the present study was to explore the interaction between glutamatergic and noradrenergic transmission. The action of prazosin, an alpha1- and alpha2b-noradrenergic antagonist, was studied here by injecting it icv (1.75 and 3.5 microg/6 microL) prior to NMDA administration (1 microg/2 microL) in OVX estrogen-primed Sprague-Dawley rats (240-270 g). Rats manually restrained were injected over a period of 2 min, and tested 1.5 h later. The enhancing effect induced by NMDA on the lordosis/mount ratio at high doses (67.06 +/- 3.28, N = 28) when compared to saline controls (6 and 2 microL, 16.59 +/- 3.20, N = 27) was abolished by prazosin administration (17.04 +/- 5.52, N = 17, and 9.33 +/- 3.21, N = 20, P < 0.001 for both doses). Plasma LH levels decreased significantly only with the higher dose of prazosin (1.99 +/- 0.24 ng/mL, N = 18, compared to saline-NMDA effect, 5.96 +/- 2.01 ng/mL, N = 13, P < 0.05). Behavioral effects seem to be more sensitive to the alpha-blockade than hormonal effects. These findings strongly suggest that the facilitatory effects of NMDA on both lordosis and LH secretion in this model are mediated by alpha-noradrenergic transmission.

Intracerebroventricular infusion of leptin into mature merino rams of different metabolic status: effects on blood concentrations of glucose and reproductive and metabolic hormones

In mature Merino rams, nutrition is one of the external cues that most strongly affects the reproductive centres of the preoptic-hypothalamic continuum. The signalling pathways that link dietary status and the activity of the neurones that produce gonadotrophin-releasing hormone signals are thought to be partly hormonal in nature to reflect the amount of body reserves. Among the hormones thought to be involved are insulin and leptin. This study tested whether recombinant bovine leptin infused (0.4 microg/h) into the third cerebral ventricle would stimulate pulsatile luteinizing hormone (LH) secretion in mature Merino rams when their energy status was low or decreasing, during both chronic (fasting) and acute reductions of energy balance. Leptin may interact with other hormones that depend on energy availability, so we also monitored changes in circulating concentrations of insulin, thyroid hormones, growth hormone, prolactin and adrenocorticotrophin. Overall, our data do not support this hypothesis. The dietary regimes induced clear responses in the metabolic profiles of the animals but there was no clear effect of central leptin administration on LH pulse frequency. The relationships between the hormonal systems measured in the present study add weight to the contention that leptin plays only a permissive role in the nutritional control of the reproductive axis and that other hormonal signals (particularly insulin) or pathways are acting in concert with leptin to stimulate the reproductive axis.

Formation of Follicular Cysts in Cattle and Therapeutic Effects of Controlled Internal Drug Release

Follicular cysts in cattle result from excessive growth of the dominant follicle without ovulation and still constitute a major reproductive disorder in this species. One key hormonal characteristic of cows with follicular cysts is the lack of an LH surge, although they have increased plasma estradiol concentrations. Another is a relatively high level of pulsatile secretion of LH that promotes continued growth of the dominant follicle. These LH characteristics seem to result from a functional abnormality in the feedback regulation of LH secretion by estradiol. Treatment with controlled internal drug release devices that increase circulating progesterone levels is effective in resolving follicular cystic conditions by 1) lowering pulsatile LH secretion and 2) restoring the ability of the hypothalamo-pituitary axis to generate an LH surge in response to an increase in circulating estradiol.

Role of Noradrenergic Receptors in the Bed Nucleus of the Stria Terminalis in Regulating Pulsatile Luteinizing Hormone Secretion in Female Rats

The bed nucleus of the stria terminalis (BNST) is one of the brain areas densely innervated by noradrenergic neurons originating in the brain stem. The present study aims to determine the role of noradrenergic receptors in the BNST in regulating pulsatile luteinizing hormone (LH) secretion in female rats. Ovariectomized (OVX) or estrogen-primed OVX (OVX+E2) rats received three 1-h-interval injections of 0.05 micromol of noradrenaline (NA), phenylephrine (alpha1-adrenergic receptor agonist), clonidine (alpha2-agonist), or isoproterenol (beta-agonist) into the BNST. Injection of NA or alpha1-adrenergic agonist into the BNST strongly suppressed pulsatile LH secretion in OVX+E2 rats with a significant (P < 0.05) decrease in the mean LH level for 3 h and LH pulse frequency, but alpha2-and beta-agonists did not affect any of the LH pulse parameters. In OVX animals, alpha1- and alpha2-adrenergic agonists caused a significant change in LH pulse frequency and amplitude, respectively, though the effect was not as apparent as the NA- or alpha1-agonist-induced changes in OVX+E2 animals. These results indicate that NA inputs to the BNST suppress pulsatile LH secretion via alpha1-adrenergic receptors and that estrogen enhances this suppression.

The effect of aromatase inhibitor, fadrozole, on sGnRHa stimulated LH secretion in goldfish (Carassius auratus) and common carp (Cyprinus carpio)

The aromatase inhibitor, fadrozole, was applied to common carp and goldfish in order to examine its ability to increase the spontaneous and sGnRHa stimulated LH secretion. First, trials in goldfish in 2003 showed fadrozole's moderate ability to potentiate sGnRHa-stimulated LH secretion. However, this ability was much weaker than that obtained with dopamine antagonist, pimozide. There was no ovulation in fadrozole-treated fish. Several experiments on goldfish and carp during the two consecutive years with the different treatment regimes and doses of fadrozole did not confirm the optimistic results obtained in 2003. This shows that fadrozole is unable to replace the antidopaminergic drugs being used in fisheries practice.

Expression of gonadotropin subunit genes following 4-nonylphenol exposure in masu salmon: Effects on transcript levels and promoter activities via estrogen receptor alpha

The 4-nonylphenol (NP) group is classified as some of the most potent endocrine disrupting chemicals (EDCs) reported to have estrogenic effects on reproductive endocrine system in vertebrates. In the present study, we investigated the effect of NP on expression of gonadotropin (GTH) subunit genes in masu salmon (Oncorhynchus masou) to clarify pituitary-based reproductive impact by EDCs. Female juvenile fish were injected with NP (a mixture of ring and chain isomers; 10 or 50 mg kg(-1) body weight) and maintained for 3 days post-injection. A semi-quantitative reverse transcription-polymerase chain reaction was used to analyze the pituitary GTHalpha, follicle-stimulating hormone beta (FSHbeta), and luteinizing hormone beta (LHbeta), and hepatic vitellogenin (VTG) mRNA levels. A low dose of NP induced the GTHalpha and LHbeta mRNA levels. High dose of NP slightly reduced FSHbeta mRNA levels in contrast to increased VTG mRNA levels. In a promoter study, NP (1-10 nM) increased the activities of luciferase reporter gene located downstream of masu salmon GTHalpha or LHbeta 5'-flanking region depending on the estrogen receptor alpha (ERalpha) in transiently transfected mammalian cells. In contrast, the luciferase activity of FSHbeta was elevated by NP in an ERalpha-independent manner. These results suggest that GTH subunit gene expression of masu salmon may be affected by EDCs at the transcription level and that the genes are useful markers for pituitary effects of xenoestrogens.

Lamprey GnRH-III Stimulates FSH Secretion in Barrows

Although studies have indicated that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release can be dissociated in the pig, the underlying mechanisms are still to be answered. Since it was demonstrated that lamprey gonadotropin-releasing hormone (l-GnRH-III) has preferential FSH-releasing potency in several mammalian species, we have investigated the gonadotropin-releasing activity of l-GnRH-III in barrows. Each of nine barrows (body weight: 85-90 kg; age: 207 days) received 2 ml saline (S-barrow), followed by 150 microg l-GnRH-III (1.6-1.7 microg/kg body weight) dissolved in 2 ml saline intramuscularly 7 days later. Three pre-treatment and 13 post-treatment blood samples were taken at intervals of 30 min to 8 h to assess basal and treatment-associated concentrations of FSH and LH, respectively, by radioimmunoassay. Animals were defined as having responded to treatment if, 2 h post-treatment, plasma FSH and/or LH levels were >3 SD of the respective basal concentrations. There was no treatment-associated FSH response after saline treatment, but a clear FSH response in all l-GnRH-III-injected barrows. On average, the maximum FSH level (205% of the basal concentration) was observed at 1 h post-treatment. Mean FSH values were elevated until 10 h post-treatment. There was no LH response either to saline or to l-GnRH-III. In conclusion, this study demonstrates a selective FSH-releasing activity of 150 microg l-GnRH-III in barrows. Further studies are needed to investigate whether this effect is ubiquitous in the pig and what the physiological relevance is.

The Stimulatory Role of Estrogen on Sperm Motility in the Male Golden Hamster (Mesocricetus auratus)

To clarify the physiological roles of estrogens in the regulation of sperm motility in the golden hamster, two different approaches were used. In the first experiment, silastic tubes containing either low (low E2 group) or high (high E2 group) amount of estradiol-17beta were implanted (Exp 1). In the second experiment, male golden hamsters were actively immunized against estradiol-17beta (Exp 2). In Exp 1, all sperm motility parameters (including motility, straight velocity, curvilinear velocity, beat/cross frequency, and mean amplitude of lateral head displacement) were significantly increased except linear index in the high E2 group as compared with controls at 20 days after the treatment. In the high E2 group, plasma concentrations of luteinizing hormone (LH) significantly increased, whereas levels of circulating testosterone decreased significantly. Plasma concentrations of follicle-stimulating hormone (FSH) and immunoreactive inhibin were not affected by the treatment with estradiol-17beta. In the Exp 2, titer of circulating antibodies to estradiol-17beta consistently increased after the second immunization until the end of experiment (16 weeks). The sperm motility, straight velocity, and curvilinear velocity were significantly decreased after active immunization to estradiol-17beta. Concentrations of circulating LH and FSH were also decreased significantly by the treatment. In conclusion, the current observations indicate that estradiol-17beta affects sperm motility in adult male golden hamsters.

A Nongenomic Action of 17β-Estradiol as the Mechanism Underlying the Acute Suppression of Secretion of Luteinizing Hormone1

The objective of the present study was to determine the ability of 17beta-estradiol (E(2)) and conjugated forms of E(2) (E(2) conjugated to BSA [E(2)-BSA] and a novel conjugate, E(2) conjugated to a small peptide [E(2)-PEP]) to prevent the GnRH-induced secretion of LH and to determine the role of estradiol receptors (ERs) and ER subtypes (ERalpha, also known as ESR1, and ERbeta, also known as ESR2) in the mediation of the acute action of E(2) in primary cultures of ovine pituitary cells. Preincubation of cells for 15 min with E(2), E(2)-BSA, or E(2)-PEP prevented the GnRH-induced secretion of LH (P < 0.01). Treatment of cells with nonestrogenic steroid hormones did not affect secretion of LH when given alone, nor did these steroids impair the E(2)-induced inhibition of LH secretion (P > 0.1). Likewise, treatment of cells with the ER-antagonists tamoxifen, hydroxytamoxifen, or ICI 182 780 did not affect (P > 0.1) secretion of LH when given alone but did prevent (P < 0.01) the inhibition by E(2) and the E(2)-conjugates on GnRH-induced secretion of LH. When cells were treated with subtype-selective ER agonists, the ERalpha agonist (propylpyrazole-triol), but not the ERbeta agonist (diarylpropionitrile), decreased (P < 0.01) the GnRH-induced secretion of LH. In conclusion, the rapidity by which E(2) prevented GnRH-induced release of LH in ovine pituitary cells suggests that this inhibition is mediated via a nongenomic action of E(2). The inhibition of GnRH-induced secretion of LH proved to be steroid specific and mediated by ERs. It may occur specifically through ERalpha. The fact that E(2)-BSA or E(2)-PEP mimicked the action of E(2) suggests that this effect was mediated by an ER associated with the plasma membrane.

Chronic cystic ovarian disease in a Holstein cow

Cystic ovarian follicles are commonly found during rectal examination of early postpartum dairy cows, usually presenting with anoestrus and occasionally nymphomania. Most cases self cure with time, or respond to exogenous hormonal treatment. This case report describes a refractory case in a Holstein cow in which a novel treatment approach was used. A gonadotrophin releasing hormone agonist implant was inserted for 180 d in an attempt to suppress pituitary gonadotrophin output, arrest abnormal ovarian follicle growth and prevent steroidogenesis. Frequent serial blood samples were collected before and after implant insertion to monitor changes in pulse release of luteinising hormone. Follow up ultrasound scans and blood samples were done to monitor ovarian structures; progesterone and oestradiol were collected at various times over the 180 d period. A normal, cycling herdmate was enrolled as a control. Prior to implant insertion, high frequency and low amplitude luteinising hormone pulses were detected in the cystic cow. Insertion was followed by a sustained surge in the release of luteinising hormone in both cows, but ovulation was not induced in the cystic cow. Plasma oestradiol levels remained consistently elevated and signs of oestrous behaviour were observed. Long term gonadotrophin releasing hormone agonist treatment failed to suppress either ovarian steroid production or cause regression of the cysts by 180 d.

Inhibition of luteinizing hormone secretion by localized administration of estrogen, but not dihydrotestosterone, is enhanced in the ventromedial hypothalamus during feed restriction in the young wether

The ability of steroids to inhibit LH secretion is enhanced during undernutrition. To identify potential hypothalamic sites at which this enhancement may occur, we examined LH secretion in feed-restricted or fed young wethers treated with locally administered metabolites of testosterone. In experiment 1, microimplants containing crystalline estradiol-17beta (E) or cholesterol were administered via chronic guide tubes directed to the preoptic area (POA) or ventromedial hypothalamus (VMH) in fed or feed-restricted wethers. E treatment in the VMH decreased LH pulse frequency, pulse amplitude, and mean LH concentration in feed-restricted, but not fed, wethers. E may act in the POA to suppress LH under feed restriction, but definite conclusions cannot be drawn because of steroid-independent effects of feed restriction on LH pulse frequency. In experiment 2, the effect of dihydrotestosterone (DHT) in the VMH was determined. DHT administration to the VMH did not alter LH secretion in either feed-restricted or fed wethers. Thus the VMH is one site wherein E negative feedback is enhanced during feed restriction in the wether. In contrast, we found no evidence for enhanced responsiveness to androgen negative feedback within the VMH of feed-restricted wethers. We suggest that increased sensitivity within the VMH to E, but not to DHT, is important for suppressing LH secretion in undernourished male sheep.

Acute Insulin-induced Hypoglycaemia does not alter IGF-1 and LH Release in Cyclic Mares

Lactation in the mare is associated with changes in the release of metabolic as well as reproductive hormones. Plasma glucose concentration is constantly reduced in lactating compared with non-lactating mares. Several metabolic signals have been proposed to link nutrition and somatic metabolism with reproductive function. The following experiment was performed to study the effect of acute hypoglycaemia on the release of insulin-like growth factor-1 (IGF-1) and luteinizing hormone (LH) in cyclic mares. Different doses of insulin (0.1 and 0.2 IU/kg body weight) were given to induce a decrease in plasma glucose concentration, as existent in lactating mares. All horses treated with insulin developed a hypoglycaemia over a time period of nearly 10 h. The IGF-1 and LH were analysed before and after insulin administration. At no point of time, a significant difference between the two insulin treatments and the control treatment was observed. Therefore, the hypoglycaemic horse is apparently able to provide the brain with sufficient glucose. Short-term hypoglycaemia does not affect the hypothalamo-pituitary-ovarian axis, and concentrations of IGF-1 and LH remained stable during insulin-induced hypoglycaemia. An acute change in plasma glucose concentration is thus not or at least not the only metabolic signal that links nutrition and somatic metabolism with reproductive function in the horse mare.

New protocol for commencing the GnRH antagonist in assisted conception treatment cycles: elimination of the premature LH surge with similar pregnancy rates

GnRH antagonists have been used with increasing frequency in assisted reproduction treatments over the past few years and have been associated with quicker and more profound LH suppression and shorter treatment cycles than conventional GnRH agonists. Usually, these are commenced on day 6 of FSH stimulation without allowing for patient variation in response to treatment. The study was aimed at individualising this protocol to the patients' ovarian response. The control group included 215 treatment cycles where the GnRH antagonist was commenced on day 6 of FSH stimulation. A new individualised protocol was formulated, applied to practice and 172 treatment cycles following that were analysed. The study group had no premature LH surges (LH > 10 iu x mL(-1)) compared to the control group who had a rate of 4.1%. There was also a higher fertilisation and clinical pregnancy rate in the study group (P = 0.06). It is concluded that the new individualised GnRH antagonist protocol eliminates premature LH surges in assisted conception treatment cycles and may improve clinical pregnancy rates compared to the conventional protocol of "day 6 commencement".

A preclinical pharmacokinetic/pharmacodynamic approach to determine a dose of GnRH, for treatment of ovarian follicular cyst in cattle

The objective of this study was to explore the value of a preclinical PK/PD approach to determine a gonadotropin-releasing hormone (GnRH) dose in cows using the pituitary LH response as a surrogate endpoint. Using an indirect effect model with stimulation of the LH entry rate, the in vivo basic pharmacodynamic parameters of GnRH were determined. The EC(50) of GnRH was 51 +/- 16 pg/mL, the EC(50) being the GnRH plasma concentration able to produce 50% of the maximum possible stimulation (S(max)) of the hypophysis (S(max) = 48 +/- 13). From individual PK/PD parameters, the ED(50) of GnRH, i.e. the estimated dose of GnRH required to determine half the maximum possible stimulating effect on LH release, was calculated to 62 microg/h per cow. Using the PK/PD model, the GnRH dose required to achieve a selected breakpoint value of 5 ng/mL for maximum LH concentration (surrogate value for LH concentration predicting clinical efficacy for cystic conditions), was 52 +/- 18 microg and for a standard GnRH dose of 100 microg, the mean maximum plasma LH concentration predicted by the model was 7.22 +/- 0.98 ng/mL.

Profound LH suppression after GnRH antagonist administration is associated with a significantly higher ongoing pregnancy rate in IVF

BACKGROUND

The significance of suppressed LH levels in GnRH antagonist cycles for IVF outcome is currently unknown. The purpose of this study was to evaluate prospectively the association between LH levels and ongoing pregnancy achievement after GnRH antagonist initiation in IVF cycles.

METHODS

Ovarian stimulation with a fixed dose of 200 IU recombinant FSH and daily GnRH antagonist (ganirelix) 0.25 mg from day 6 of stimulation was initiated in 116 women. Patients were not pretreated with an oral contraceptive. Induction of final oocyte maturation was performed with HCG 10,000 IU as soon as three follicles of > or =17 mm were present in ultrasound, and was followed by oocyte pick-up, conventional IVF or ICSI, and embryo transfer. The luteal phase was supplemented with vaginal progesterone.

RESULTS

A significant decrease of both ongoing pregnancy rate and implantation rate was present across groups of patients with increasing LH levels. The highest implantation rate and ongoing pregnancy rate was present in those patients with LH levels on day 8 of stimulation < or =0.5 IU/l.

CONCLUSIONS

Profound suppression of LH on day 8 of stimulation is associated with a significantly higher chance of achieving an ongoing pregnancy. More studies are necessary to evaluate this phenomenon further.

[The programming of IVF cycles with antagonists]

Modern gonadotrophin-releasing hormone (GnRH) antagonists such as cetrorelix and ganirelix reliably prevent premature LH surge in controlled ovarian hyperstimulation for assisted reproductive technologies. Nevertheless, GnRH antagonists do not allow homogenization of the follicle cohort, as observed with GnRH agonists. Administration of estrogens, progestogens or contraceptive pill in previous late luteal phase, may improve the size homogeneity of antral follicles. The coordination of follicular development may optimize ovarian response to r-FSH/GnRH antagonist protocols.

[Onset and maintenance of the luteal phase with GnRH agonists or hCG in cycles under GnRH antagonists]

Corpus luteum function seems to be impaired in IVF cycles with COH (Controlled Ovarian Hyperstimulation) and GnRH antagonist. Support of corpus luteum function remains mandatory after ovarian stimulation for IVF with GnRH antagonist cotreatment. GnRH antagonists do not have any impact on the luteal phase of IVF/ICSI cycles when hormonal support is given. A new treatment option for patients undergoing ovarian stimulation is the gonadotrophin-releasing hormone (GnRH) antagonist protocol, with the possibility to trigger a mid-cycle LH surge using a single bolus of GnRH agonist, reducing the risk of developing ovarian hyperstimulation syndrome (OHSS) in high responders. In IVF cycle with COH and GnRH antagonist, support of corpus luteum function is essential, whatever molecule to trigger LH surge (hCG, r-hLH, GnRH agonist). Adequate luteal support (progesterone and estrogens) compensates for luteolysis and assures good clinical outcome.

[GnRH antagonists in natural cycles]

Since the introduction of IVF treatments, natural cycle has been largely replaced by ovarian stimulation. However, natural cycle IVF has several advantages. It is associated with a close to zero multiple pregnancy rate, and a zero risk of ovarian hyperstimulation syndrome. Per cycle, natural cycle IVF is less time consuming, physically and emotionally less demanding for patients, and cheaper than stimulated IVF, but also less effective. Many cycles are cancelled because of a premature LH surge. GnRH antagonists prevent LH surge and therefore improve the results of natural IVF cycles. The GnRH antagonist should be started at day 8, at the daily dose of 0.5 mg. The natural cycle is a successful option of treatment in poor responders and implantation failure.