Successful use of pulsatile gonadotropin-releasing hormone (GnRH) for ovulation induction and pregnancy in a patient with GnRH receptor mutations

GnRH receptor mutations have recently been identified in a small number of familial cases of nonanosmic hypogonadotropic hypogonadism. In the present report we studied a kindred in which two sisters with primary amenorrhea were affected with GnRH deficiency due to a compound heterozygote mutation (Gln(106)Arg, Arg(262)Gln) and performed extensive phenotyping studies. Baseline patterns of gonadotropin secretion and gonadotropin responsiveness to exogenous pulsatile GnRH were examined in the proband. Low amplitude pulses of both LH and free alpha-subunit (FAS) were detected during 24 h of every 10 min blood sampling. The proband then received exogenous pulsatile GnRH i.v. for ovulation induction, and daily blood samples for gonadotropins and sex steroids were monitored. At the conventional GnRH replacement dose for women with hypogonadotropic hypogonadism (75 ng/kg), no follicular development occurred. At a GnRH dose of 100 ng/kg, the level and pattern of gonadotropin secretion more closely mimicked the follicular phase of normal women; a single dominant follicle was recruited, and an endogenous LH surge was elicited. However, the luteal phase was inadequate, as assessed by progesterone levels. At a GnRH dose of 250 ng/kg, the gonadotropin and sex steroid dynamics reproduced those of normal ovulatory women in both the follicular and luteal phases, and the proband conceived. The FAS responses to both conventional and high dose GnRH were within the normal range. The following conclusions were made: 1) Increased doses of GnRH may be used effectively for ovulation induction in some patients with GnRH receptor mutations. 2) Higher doses of GnRH are required for normal luteal phase dynamics than for normal follicular phase function. 3) Hypersecretion of FAS in response to exogenous GnRH, which is a feature of congenital hypogonadotropic hypogonadism, was not seen in this patient with a GnRH receptor mutation.     

Specific factors predict the response to pulsatile gonadotropin-releasing hormone therapy in polycystic ovarian syndrome

Ovulation induction is particularly challenging in patients with polycystic ovarian syndrome (PCOS) and may be complicated by multifollicular development. Pulsatile GnRH stimulates monofollicular development in women with anovulatory infertility; however, ovulation rates are considerably lower in the subgroup of patients with PCOS. The aim of this retrospective study was to determine specific hormonal, metabolic, and ovarian morphological characteristics that predict an ovulatory response to pulsatile GnRH therapy in patients with PCOS. Subjects with PCOS were defined by chronic amenorrhea or oligomenorrhea and clinical and/or biochemical hyperandrogenism in the absence of an adrenal or pituitary disorder. At baseline, gonadotropin dynamics were assessed by 10-min blood sampling, insulin resistance by fasting insulin levels, ovarian morphology by transvaginal ultrasound, and androgen production by total testosterone levels. Intravenous pulsatile GnRH was then administered. During GnRH stimulation, daily blood samples were analyzed for gonadotropins, estradiol (E(2)), progesterone, inhibin B, and androgen levels, and serial ultrasounds were performed. Forty-one women with PCOS underwent a total of 144 ovulation induction cycles with pulsatile GnRH. Fifty-six percent of patients ovulated with 40% of ovulatory patients achieving pregnancy. Among the baseline characteristics, ovulatory cycles were associated with lower body mass index (P < 0.05), lower fasting insulin (P = 0.02), lower 17-hydroxyprogesterone and testosterone responses to hCG (P < 0.03) and higher FSH (P < 0.05). In the first week of pulsatile GnRH treatment, E(2) and the size of the largest follicle were higher (P < 0.03), whereas androstenedione was lower (P < 0.01) in ovulatory compared with anovulatory patients. Estradiol levels of 230 pg/mL (844 pmol/L) or more and androstenedione levels of 2.5 ng/mL (8.7 nmol/L) or less on day 4 and follicle diameter of 11 mm or more by day 7 of pulsatile GnRH treatment had positive predictive values for ovulation of 86.4%, 88.4%, and 99.6%, respectively. Ovulatory patients who conceived had lower free testosterone levels at baseline (P < 0.04). In conclusion, pulsatile GnRH is an effective and safe method of ovulation induction in a subset of patients with PCOS. Patient characteristics associated with successful ovulation in response to pulsatile GnRH include lower body mass index and fasting insulin levels, lower androgen response to hCG, and higher baseline FSH. In ovulatory patients, high free testosterone is negatively associated with pregnancy. A trial of pulsatile GnRH therapy may be useful in all PCOS patients, as E(2) and androstenedione levels on day 4 or follicle diameter on day 7 of therapy are highly predictive of the ovulatory response in this group of patients.     

Ovulation induction with pulsatile gonadotropin-releasing hormone and continuous human menopausal gonadotropin in polycystic ovarian disease

Various treatments have been applied to polycystic ovarian (PCO) type of anovulation. However, none of them was definitive in terms of the efficacy and side effects. Six anovulatory women of PCO type were treated with pulsatile gonadotropin-releasing hormone (GnRH) of various pulse intervals and continuous human menopausal gonadotropin (hMG). The efficacy and rationale of the treatments were discussed. The subjects were diagnosed PCO by GnRH test and/or laparoscopy. They did not ovulate with clomiphene, clomiphene-hCG and hMG-hCG therapies. Their pretreatment serum FSH and LH levels and FSH/LH ratios were 6.9 +/- 1.2 mIU/ml, 15.7 +/- 5.1 mIU/ml, and 0.54 +/- 0.19 (Mean +/- SD), respectively. The treatment consisted of 3 protocols: 1) pulsatile GnRH (5-10 micrograms/pulse) of 90 min interval, 2) pulsatile GnRH (5-10 micrograms/pulse) of 120 min interval and 3) continuous hMG (150 IU/day) through subcutaneous route. Follicular growth was monitored sonographically and an intramuscular bolus of 10,000 IU hCG was given when the dominant follicle reached 20 mm in diameter. During both GnRH treatments serum FSH levels and FSH/LH ratios did not elevate substantially. Serum LH, E2 and PRL levels elevated acutely and transiently during the initial phase of GnRH treatments. Follicular growth was observed in a small fraction of the cases, but none of them ovulated. In contrast, continuous hMG treatment induced significant elevation in serum FSH levels (8.2 +/- 1.7 mIU/ml; p less than 0.01) and FSH/LH ratios (1.73 +/- 0.57; p less than 0.001). Transient hyperprolactinemia was accompanied with the preovulatory E2 rise. All the cases ovulated and 3 singleton pregnancies followed. These findings draw conclusions as follows. Pulsatile GnRH administration may desensitize the pituitary presumably due to increased GnRH pulse frequency as a consequence of two independent pulse generators, intrinsic and exogeneous. It may induce transient hyperprolactinemia through a paracrine system between gonadotrophs and lactotrophs. As a due course pulsatile GnRH therapy is questionable for ovulation induction in cases with functioning hypothalamic-pituitary axis. The fact that continuous hMG effectively induced follicle maturation with elevated FSH/LH ratios suggested that FSH dominance might be a prerequisite for folliculogenesis. The fluctuating nature of gonadotropins might not be mandatory for folliculogenesis.     

Clinical review 15: Management of ovulatory disorders with pulsatile gonadotropin-releasing hormone

Pulsatile GnRH therapy has yet to achieve widespread acceptance as an alternative to exogenous gonadotropin therapy in women with hypothalamic amenorrhea and complete GnRH deficiency. However, when a physiologically based replacement regimen of pulsatile GnRH is used, a high rate of ovulation and conception can be anticipated in patients with complete GnRH deficiency and hypothalamic amenorrhea. Women with polycystic ovarian syndrome may also benefit from pulsatile GnRH, although rates of ovulation are lower. Pretreatment with a GnRH agonist may improve these rates considerably, but experience is limited. Whether an iv or sc route of administration is chosen, a simplified clinical monitoring protocol can be created which requires a minimum of patient monitoring while assuring maximum safety. Seventy five nanograms per kg appears to be a reasonable initiating dose, with subsequent increases in those who do not respond. The frequency of GnRH administration is best based on the GnRH pulse frequency in normal women. However, further information is needed to determine whether such a variable frequency is clearly superior to a fixed frequency regimen. When used appropriately, pulsatile GnRH is safe, effective, and offers an excellent alternative to conventional gonadotropin therapy for women with disordered endogenous GnRH secretion. Most importantly, and as opposed to exogenous gonadotropin therapy, pulsatile GnRH can be administered by most physicians in the office setting without the necessity of on-line E2 monitoring. This feature will enable more patients to receive treatment by their local physicians, whereas exogenous gonadotropin therapy should be administered by appropriately equipped referral centers. In the future, further studies will be required to determine which other categories of patients might benefit from pulsatile GnRH.     

Relationship between follicle size at insemination and pregnancy success

Administration of gonadotropin-releasing hormone (GnRH) induces a surge of luteinizing hormone and ovulation in a variety of species, including human beings. Our objectives were to determine the effect of follicle size at the time of ovulation on corpus luteum function and establishment and maintenance of pregnancy in cows in which ovulation was either spontaneous or induced with GnRH. GnRH-induced ovulation of follicles < or approximately = 11 mm in diameter resulted in decreased pregnancy rates and increased late embryonic mortality. This decrease in fertility was associated with lower circulating concentrations of estradiol on the day of insemination, a decreased rate of increase in progesterone after insemination, and, ultimately, decreased circulating concentrations of progesterone. In contrast, ovulatory follicle size had no apparent effect on fertility when ovulation occurred spontaneously. Follicles undergoing spontaneous ovulation do so at a wide range of sizes when they are physiologically mature. Therefore, administration of GnRH to induce ovulation likely initiates a preovulatory gonadotropin surge before some dominant follicles attain physiological maturity. GnRH-induced ovulation of follicles that are physiologically immature has a negative impact on pregnancy rates and late embryonic/fetal survival. These observations in cattle may have implications for assisted reproductive procedures in human beings.     

Resistance of hypogonadic patients with mutated GnRH receptor genes to pulsatile GnRH administration

We have studied a kindred with three siblings with isolated hypogonadotropic hypogonadism caused by compound heterozygote mutations in the GnRH receptor gene. The disorder was transmitted as an autosomal recessive trait. The R262Q mutation in intracellular loop 3 of the receptor was associated with a mutation in the third transmembrane domain of the receptor, A129D, that has never been described before. This A129D mutation results in a complete loss of function, indicated by the lack of inositol triphosphate (TP3) 3 production by transfected Chinese hamster ovary (CHO) cells after GnRH stimulation. The two brothers had microphallus and bilateral cryptorchidism and were referred for lack of puberty, whereas their sister had primary amenorrhea and a complete lack of puberty. Their basal gonadotropin concentrations were below the reference range, and their endogenous LH secretory patterns were abnormal, with a low-normal frequency of small pulses or no apparent LH pulse. Pulsatile GnRH administration (10 microg/pulse every 90 min for 40 h) resulted in increased mean LH without any significant changes in testosterone levels in the two brothers, whereas the LH secretory profile of their sister remained apulsatile. Larger pulses of exogenous GnRH (20 microg every 90 min for 24 h) caused the sister to produce recognizable low amplitude LH pulses. The concentrations of free alpha-subunit significantly increased in all patients during the pulsatile GnRH administration. Thus, these hypogonadal patients are partially resistant to pulsatile GnRH administration, suggesting that they should be treated with gonadotropins to induce spermatogenesis or ovulation rather than with pulsatile GnRH.     

Naltrexone effect on pulsatile GnRH therapy for ovulation induction in polycystic ovary syndrome: a pilot prospective study

The aim of the present study was to analyze the opioid influence on LH pulsatility in polycystic ovary syndrome (PCOS) patients and to evaluate the effectiveness of a long-term opioid antagonist (naltrexone) treatment in improving the pulsatile GnRH therapy which is successful in this syndrome. Ten obese women affected by PCOS participated in the study. Patients were hospitalized during the early follicular phase and underwent an oral glucose tolerance test (OGTT) with 75 g of glucose and a pulse pattern study followed by a GnRH test (100 pg i.v.). All patients were then treated for ovulation induction with pulsatile administration of GnRH (5 microg/bolus every 90 min). Since pregnancies did not occurr in any patient, after spontaneous or progestin-induced menstrual cycles, all patients received naltrexone at a dose of 50 mg/day orally for 8 weeks and during treatment repeated the basal protocol study and the ovulation induction cycle with the same modalities. The naltrexone treatment significantly reduced the insulin response to OGTT and the LH response to GnRH bolus, whereas it did not affect the FSH and LH pulsatility patterns. Concerning the ovulation induction by pulsatile GnRH, naltrexone treatment was able to improve, although not significantly, the ovulation rate (60% pre-treatment vs 90% post-treatment). Furthermore, the maximum diameter of the dominant follicle and the pre-ovulatory estradiol concentration were higher after long-term opioid blockade (follicular diameter 19.5+/-1.76 mm pre-treatment vs 21.6+/-2.19 mm post-treatment, p<0.001; maximum estradiol level 728.7+/-288.5 pmol/l pre-treatment vs 986.4+/-382.1 pmol/l post-treatment, p<0.05). During the naltrexone-pulsatile GnRH co-treatment two pregnancies occurred. In conclusion, our data show that naltrexone-pulsatile GnRH co-treatment is able to improve the ovarian responsiveness to ovulation induction in obese PCOS patients when compared to pulsatile GnRH alone. This action seems to be related to a decrease of insulin secretion. Further randomized studies should be performed in order to obtain significant conclusions on the possible clinical application.     

Two-year comparison of testicular responses to pulsatile gonadotropin-releasing hormone and exogenous gonadotropins from the inception of therapy in men with isolated hypogonadotropic hypogonadism

Men with the complete form of isolated hypogonadotropic hypogonadism (initial mean testes volume less than 4 mL) require 2 or more yr of exogenous gonadotropin therapy combining hCG and human menopausal gonadotropin (hMG) to achieve maximal, but subnormal, testis size and sperm output. To test whether pulsatile GnRH therapy, which more closely mimics normal hormonal stimulation, would accelerate or further augment testicular growth, hasten the onset of sperm production, and/or increase sperm output more than occurs during conventional exogenous gonadotropin therapy, we administered either hCG/hMG or GnRH from the inception of therapy to 2 comparable groups of men with complete IHH (initial testicular volume, less than 4 mL) and compared their testicular responses during the first 2 hr of therapy. Five men were treated with pulsatile GnRH in doses of 143-714 ng/kg every 2 h, sc, while 11 other men received hCG (2000 IU) and hMG (75 IU FSH and 75 IU LH) im 3 times/week. In the GnRH-treated men, the mean plasma total and free testosterone levels during therapy rose to within the normal range, but were significantly lower (P less than 0.01 and P less than 0.02, respectively) than those in the hCG/hMG-treated men. The mean plasma estradiol concentrations during therapy were within the high normal range and were similar in the two groups. The mean plasma FSH levels achieved in the GnRH-treated men were significantly (P less than 0.01) and 1.3- to 3.2-fold higher than those in the hCG/hMG-treated men. The mean testicular size achieved in the GnRH-treated men was not significantly different from that in the hCG/hMG-treated men (P = 0.08); the mean testicular volumes after 2 yr were 4.8- and 4.3-fold the pretreatment values in the GnRH and hCG/hMG groups, respectively. After 12 months of therapy, sperm production had occurred in one man in the GnRH group and in no subject in the hCG/hMG group. After 24 months, two men in the GnRH group and eight men in the hCG/hMG group produced sperm. Thus, 40% of the GnRH-treated men and 80% of the hCG/hMG-treated men (P = NS) produced sperm after 2 yr of therapy. The sperm concentrations in all men were below 5 million/mL and were comparable in the two groups (P = NS). These results suggest that pulsatile sc GnRH therapy for the first 2 yr does not accelerate or enhance testicular growth, hasten the onset of sperm production, or increase sperm output significantly compared to hCG/hMG.     

The abnormal response of polycystic ovarian disease patients to exogenous pulsatile gonadotropin-releasing hormone: characterization and management

Pulsatile GnRH administration for induction of ovulation is often ineffective in polycystic ovarian disease (PCOD) patients. To clarify and correct the endocrine mechanisms underlying this deranged response we gave pulsatile GnRH (5 micrograms, iv, every 60 min) to idiopathic hypogonadotropic hypogonadism (IHH) patients with primary amenorrhea for 19 cycles and to PCOD patients for 24 cycles before (pre-A) and for 25 cycles after (post-A) GnRH analog suppression. Compared to IHH, pre-A cycles were characterized by elevated LH, estradiol, and testosterone; reduced luteal phase progesterone; and low ovulatory (38%) and pregnancy rates (8%). Conversely, LH, estradiol, and follicular phase testosterone levels were lower in post-A than in pre-A cycles, while luteal phase progesterone was higher; the endocrine pattern of post-A cycles closely resembled the one of IHH cycles. The ovulatory and pregnancy rates of PCOD patients improved remarkably in post-A cycles (90% and 38%, respectively). Excessive body weight was associated with a lower incidence of ovulation in both pre-A (15%) and post-A cycles (75%). A worse endocrine pattern and a lower ovulatory rate (50%) were obtained when a second consecutive post-A cycle occurred without repeating GnRH analog suppression. No signs of even mild ovarian hyperstimulation and no multiple pregnancies were recorded in the post-A cycles. We conclude that in PCOD 1) deranged pituitary sensitivity, excessive ovarian androgen secretion, and obesity critically affect folliculogenesis and ovulation; 2) pituitary-gonadal suppression with a GnRH analog markedly improves the endocrine and clinical responses to pulsatile GnRH ovulation induction; 3) optimal results can be achieved only when each pulsatile GnRH cycle is preceded by GnRH analog suppression; and 4) pulsatile GnRH is highly effective and safe for ovulation induction, provided that PCOD subjects are pretreated with a GnRH analog.     

The antigonadotropic activity of a 19-nor-progesterone derivative is exerted both at the hypothalamic and pituitary levels in women

We have previously shown in postmenopausal women that a 19-nor-progesterone derivative, nomegestrol acetate (NOMA) had a strong antigonadotropic activity and that this effect was not mediated via the androgen receptor. The aim of the present study was to further assess the action of this progestin on gonadotropin secretion in women. To demonstrate at which level of the hypothalamo-pituitary-ovarian axis the gonadotropin inhibition was exerted, 10 normally cycling (NC) women, 3 women with a gonadotropin-independent ovarian function [McCune-Albright (MCA) syndrome], and 5 women with functional hypothalamic amenorrhea (FHA) participated in the study. NC women were treated orally with 5 mg NOMA for 21 days, after one control cycle. Plasma estradiol (E2) and progesterone, LH, and FSH levels were measured during each cycle. A frequent sampling study (every 10 min for 4 h), followed by a classic GnRH test (100 microg, i.v.), was performed on day 11. Women with MCA were studied before, during NOMA, and after long-acting GnRH agonist administration. In women with FHA, pulsatile GnRH (20 microg s.c., every 90 min) was given for two cycles with or without NOMA (5 mg for 21 days). In all NC women, ovulation was suppressed by NOMA. Mean plasma LH levels, LH pulse frequency, and the LH response to exogenous GnRH were significantly decreased. In MCA, neither NOMA nor GnRH agonist modified multiple ovarian cysts on ultrasound or plasma E2, levels which remained elevated, ruling out a direct ovarian effect. In FHA, pulsatile GnRH administration recreated a normal ovulatory menstrual cycle. Addition of NOMA prevented the increase of plasma E2, decreased the amplitude of LH pulses, and prevented ovulation. In view of this unexpected action of NOMA at the pituitary level, seven samples of normal human female pituitaries were tested for the presence of progesterone receptor (PR) using a double labeling immunocytochemical technique. The presence of PR was detected in the seven human pituitary tissues. In addition, PR was found to be expressed only in gonadotroph cells. In conclusion, NOMA, a 19-nor-P derivative, has a potent antigonadotropic activity exerted at the hypothalamic level, inhibiting ovulation in NC women. In women with FHA, NOMA decreased the gonadotropin stimulation induced by pulsatile GnRH administration. According to the presence of PR in gonadotroph cells of normal human pituitaries, 19-nor-progesterone derivatives may also act on the gonadotropin secretion at the pituitary level.     

Hormone substitution in male hypogonadism

Male hypogonadism is characterised by androgen deficiency and infertility. Hypogonadism can be caused by disorders at the hypothalamic or pituitary level (hypogonadotropic forms) or by testicular dysfunction (hypergonadotropic forms). Testosterone substitution is necessary in all hypogonadal patients, because androgen deficiency causes slight anemia, changes in coagulation parameters, decreased bone density, muscle atrophy, regression of sexual function and alterations in mood and cognitive abilities. Androgen replacement comprises injectable forms of testosterone as well as implants, transdermal systems, sublingual, buccal and oral preparations. Transdermal systems provide the pharmacokinetic modality closest to natural diurnal variations in testosterone levels. New injectable forms of testosterone are currently under clinical evaluation (testosterone undecanoate, testosterone buciclate), allowing extended injection intervals. If patients with hypogonadotropic hypogonadism wish to father a child, spermatogenesis can be initiated and maintained by gonadotropin therapy (conventionally in the form of human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG) or, more recently, purified or recombinant follicle stimulating hormone (FSH)). Apart from this option, patients with disorders at the hypothalamic level can be stimulated with pulsatile gonadotropin-releasing hormone (GnRH). Both treatment modalities have to be administered on average for 7-10 months until pregnancy is achieved. In individual cases, treatment may be necessary for up to 46 months. Testosterone treatment is interrupted for the time of GnRH of gonadotropin therapy, but resumed after cessation of this therapy.     

Preovulatory follicle development and luteal function in ewes immunized against a synthetic peptide sequence of the alpha subunit of bovine inhibin.

Immunization against inhibin consistently results in an increase in ovulation rate in sheep, but the effects that this treatment has on follicle development are unknown. In order to determine the influence of inhibin, parameters of follicle development were assessed in ewes that had been actively immunized against a synthetic peptide homologous to the N-terminal sequence (alpha 1-29, Tyr30) of the alpha subunit of bovine inhibin, a treatment that neutralizes the biological activity of endogenous inhibin. The final stages of preovulatory follicle development that culminate in ovulation were induced in seasonally anoestrous ewes, and follicles were recovered prior to the predicted time of ovulation. After priming with progestagen, inhibin-immunized and control ewes were treated with gonadotrophin-releasing hormone (GnRH) by continuous infusion (200 ng/h). The ovaries were recovered at slaughter 24 h after the start of GnRH treatment and all follicles greater than or equal to 2.0 mm diameter were dissected out and their capacity to produce oestradiol in vitro was assessed. Further groups of similarly treated animals were blood-sampled daily to determine luteal function following GnRH-induced ovulation. The ovaries were recovered from these ewes at slaughter 10 days after the start of GnRH treatment, the corpora lutea were dissected out and their progesterone content was assessed. There were more (P less than 0.01) follicles of 5-6 mm diameter (3.2 +/- 0.45 (S.E.M.) compared with 1.1 +/- 0.25 follicles/ewe) and more (P less than 0.001) follicles of greater than 6 mm diameter (2.8 +/- 0.56 compared with 0.9 +/- 0.17 follicles/ewe) in inhibin-immunized than in control ewes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maintenance of spermatogenesis in hypogonadotropic hypogonadal men with human chorionic gonadotropin alone

OBJECTIVE: It is generally accepted that both gonadotropins LH and FSH are necessary for initiation and maintenance of spermatogenesis. We investigated the relative importance of FSH for the maintenance of spermatogenesis in hypogonadotropic men. SUBJECTS AND METHODS: 13 patients with gonadotropin deficiency due to idiopathic hypogonadotropic hypogonadism (IHH), Kallmann syndrome or pituitary insufficiency were analyzed retrospectively. They had been treated with gonadotropin-releasing hormone (GnRH) (n=1) or human chorionic gonadotropin/human menopausal gonadotropin (hCG/hMG) (n=12) for induction of spermatogenesis. After successful induction of spermatogenesis they were treated with hCG alone for maintenance of secondary sex characteristics and in order to check whether sperm production could be maintained by hCG alone. Serum LH, FSH and testosterone levels, semen parameters and testicular Volume were determined every three to six Months. RESULTS: After spermatogenesis had been successfully induced by treatment with GnRH or hCG/hMG, hCG treatment alone continued for 3-24 Months. After 12 Months under hCG alone, sperm counts decreased gradually but remained present in all patients except one who became azoospermic. Testicular Volume decreased only slightly and reached 87% of the Volume achieved with hCG/hMG. During treatment with hCG alone, FSH and LH levels were suppressed to below the detection limit of the assay. CONCLUSION: Once spermatogenesis is induced in patients with secondary hypogonadism by GnRH or hCG/hMG treatment, it can be maintained in most of the patients qualitatively by hCG alone, in the absence of FSH, for extended periods. However, the decreasing sperm counts indicate that FSH is essential for maintenance of quantitatively normal spermatogenesis.     

Growth hormone (GH) substitution in hypogonadotropic, GH-deficient women decreases the follicle-stimulating hormone threshold for monofollicular growth

The FSH threshold concept for monofollicular growth (which means that at the time the largest follicle reaches 18 mm there are no other follicles with a diameter of 13-18 mm also present) was used during ovulation induction in hypogonadotropic women, who appeared to be GH deficient. This concept was used to investigate whether 1) GH influences the FSH threshold for monofollicular growth and 2) whether such an influence would depend upon the endogenous GH/insulin-like growth factor I (IGF-I)/IGF-binding protein-3 (IGFBP-3) levels. In six hypogonadotropic women the GH response after an insulin challenge did not exceed 6 microg/L. Patients underwent ovulation induction according to a low dose step-up protocol by hMG during two consecutive cycles. GH substitution was provided only during the second cycle. Except for one GH treated cycle, all cycles were ovulatory. IGF-I levels as well as IGFBP-3 levels significantly increased (P < 0.01) during GH substitution. Monofollicular growth was not achieved in the first cycles. In five of six GH-substituted cycles, monofollicular growth was obtained. FSH threshold levels decreased in all patients during GH substitution. The FSH area under the curve was negatively correlated to IGF-I (r = -0.6; P < 0.05) and IGFBP-3 (r = -0.6; P < 0.05). The results of this study indicate that GH may play a role in the physiological growth of the follicle; most likely this occurs by influencing the IGF-I or IGFBP-3 levels. GH appears to selectively increase the sensitivity of the dominant follicle to FSH, facilitating monofollicular growth.     

Hypothalamic dysfunction

A pulsatile GnRH stimulus is required to maintain gonadotropin synthesis and secretion. The frequency and amplitude of GnRH pulses determine gonadotropin subunit gene expression and secretion of pituitary LH and FSH. Rapid frequency (more than 1 pulse per h) GnRH pulses favor LH while slower frequencies favor FSH secretion. During ovulatory cycles, an increase in GnRH frequency during the follicular phase favors LH synthesis prior to the LH surge, while following ovulation, luteal steroids slow GnRH pulses to favor FSH synthesis. Thus, a changing frequency of GnRH stimulation of the gonadotrope is one of the mechanisms involved in differential gonadotropin secretion during ovulatory cycles. In hypothalamic amenorrhea a majority of women exhibit a persistent slow frequency of LH (GnRH) pulses, which reflects excess hypothalamic opioid tone and can be temporarily reversed by opioid antagonists. At the other end of the spectrum, in polycystic ovarian syndrome, LH (GnRH) pulses are persistently rapid and favor LH synthesis, hyperandrogenism and impaired follicular maturation. Administration of progesterone can slow GnRH pulse secretion, favor FSH secretion and induce follicular maturation. Thus, the ability to change the pattern of GnRH secretion is an important factor in the maintenance of cyclic ovulation, and loss of this function leads to anovulation and amenorrhea.     

Functional and structural relationships in steroidogenesis in vitro by human ovarian follicles during maturation and ovulation.

To investigate steroidogenic function of human follicles in the light of their structures, eight antral follicles of different sizes were mechanically isolated from ovaries of patients laparotomized in the follicular phase of the menstrual cycle with or without pretreatment with human menopausal gonadotropin (hMG). A portion of each follicle was taken for histology and slices of each follicle were incubated with [1-14C]-acetate. Incorporation into progestins, androgens, and estrogens was assessed by the reverse dilution technique with recrystallization to constant specific activity. A predominant incorporation into 17 beta-estradiol was observed in two maturing follicles, whereas a marked increase in incorporation into 17 beta-estradiol with a concomitant decrease in incorporation into androstenedione was verified in two other mature follicles. Remarkable enhancement in relative incorporation into C21 steroids was commonly noted in four preovulatory follicles. However, with the progress of preovulatory stages toward ovulation, as judged from structural changes of the follicles, actual incorporation into C19 and C18 steroids showed a moderate increase, followed by a drastic decrease around the time of ovulation. hMG injection induced similar relationships between the steroidogenic pattern and the follicle structure of different stages, although overall incorporation was considerably increased. We conclude that marked qualitative and quantitative changes in the steroidogenic function and accompanying corresponding changes in structure occurred over the period of follicular maturation and ovulation.     

Effect of gonadotrophin-releasing hormone agonist-induced suppression of LH and FSH on follicle growth and corpus luteum function in the ewe

Continuous infusion of a gonadotrophin-releasing hormone (GnRH) agonist (buserelin) by osmotic minipump from day 1 of the luteal phase in five Welsh ewes resulted in a sustained suppression of plasma concentrations of FSH which increased three- to eightfold within 2 days after the end of infusion 29 days later. Plasma concentrations of LH increased three- to eightfold over the first 5 days of infusion and then became basal and non-pulsatile until 1 day after the end of infusion. Duration of the luteal phase and plasma concentrations of progesterone were not significantly different in control and treated ewes. Pulses of LH in control ewes were followed by increases in concentrations of progesterone in samples collected at 10-min intervals for 7 h on days 10 and 14 of the luteal phase. However, progesterone was also released in a pulsatile manner in the absence of LH pulses in both control and GnRH agonist-treated ewes. After natural luteolysis, no ovulation or corpus luteum function occurred in treated ewes up to 15 days after the end of treatment on day 29, even though oestrus, indicating follicular development and oestrogen secretion, had occurred 8-11 days after treatment ended. After 30 days of infusion the ovaries of GnRH agonist-treated ewes contained no follicles greater than 2.5 mm in diameter. In follicles of 1-2 mm in diameter the basal and LH-stimulated production of oestradiol and testosterone in vitro were similar in both control and GnRH agonist-treated ewes, and a similar proportion of these follicles was oestrogenic (greater than 370 mol oestradiol per follicle) in GnRH agonist-treated and control ewes. These results show (1) that progesterone secretion by the corpus luteum of the ewe can be sustained in the presence of basal concentrations but absence of pulsatile secretion of LH, and progesterone is released in a pulsatile manner whether or not LH pulses are present, (2) that follicular development beyond 2.5 mm in diameter in the ewe is dependent upon adequate stimulation by both LH and FSH and (3) that the continuous infusion of GnRH agonist is a simple method for providing reproducible suppression of LH and FSH and follicular development in the ewe to allow the study of gonadotrophin action on the ovary in vivo.     

GnRH AGONIST ADMINISTRATION IN POLYCYSTIC OVARY SYNDROME

The study was designed to examine (1) the effects of the luteinizing hormone releasing hormone (GnRH) agonist, buserelin, on pituitary and ovarian hormone secretion, and (2) the effect that pituitary-ovarian suppression with a GnRH agonist has on subsequent ovulation induction with exogenous gonadotrophins (hMG), in polycystic ovary syndrome (PCOS). Two protocols were studied where buserelin was administered intranasally to all patients in a dose of 200 micrograms, six times daily. Ten patients received buserelin until an oestrogen withdrawal bleed occurred while a further 12 patients received buserelin for 4 weeks, before hMG was co-administered. Nine of the above subjects also underwent conventional ovulation induction with hMG. Blood samples were taken daily for radioimmunoassay of LH (LH-RIA), FSH, sex steroids and inhibin and for immunoradiometric assay of LH (LH-IRMA). Following buserelin administration there was an initial rise in LH-RIA, FSH, oestradiol (E2) and inhibin (P less than 0.01). Fourteen days were needed for LH-RIA to return to the normal range, with both protocols resulting in a fall in LH-RIA and FSH (P less than 0.01) before hMG was co-administered. Twenty-eight days of buserelin administration were needed to suppress E2 into the castrate range. Inhibin and both E2 and FSH were closely correlated throughout buserelin administration (P less than 0.01). There was failure to respond to an intravenous bolus of 100 micrograms of GnRH from 7 days of buserelin administration onwards, despite the serum LH-RIA still being raised at 7 days. Serum samples assayed for LH by RIA using WHO Matched Reagents and by IRMA were closely correlated (r = 0.96, P less than 0.01). There was no difference in the proportion of ovulations (52% vs 66%) or pregnancies (1 vs 1) in the GnRH agonist or control group. Similar amounts of hMG were needed in both groups and there was multiple follicular development (greater than 3 follicles greater than 15 mm diameter; 41% vs 38%) following hMG administration. There was a close correlation between E2 and inhibin levels (P less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)     

Ovulation stimulation and induction.

Evaluation of gonadotropins, prolactin, and thyroid function in anovulatory women directs subsequent therapy. Treatment should be initiated with the agent that is the safest and least costly for the specific indication. Except in cases of FSH elevation, pregnancy rates should approximate those of normally ovulating women. Bromocriptine, the drug of choice for hyperprolactinemia, restores ovulation in greater than 90% of women treated. Clomiphene citrate remains the drug of choice for normoestrogenic anovulation. Although drug-resistant women may respond to extended regimens, failure to ovulate or to conceive within six ovulatory cycles with clomiphene is an indication for menotropin therapy. Menotropins and pulsatile GnRH should be considered first line therapy for women with hypogonadotropic anovulation. When using hMG or pulsatile GnRH in clomiphene-resistant patients, pretreatment with GnRH analogs may normalize their response and result in higher pregnancy rates. GnRH analogs prevent premature luteinization in hMG-induced in vitro fertilization and gamete intrafallopian transfer cycles, resulting in lower cancellation rates and improved oocyte quality. Superovulation with clomiphene citrate should be attempted in patients with unexplained infertility prior to using menotropin therapy.