The importance of signal pattern in the transmission of endocrine information: pituitary gonadotropin responses to continuous and pulsatile gonadotropin-releasing hormone

We tested the hypothesis that pulsatile GnRH stimulation of the pituitary is required for normal gonadotropin secretion in humans. We administered GnRH in pulsatile and continuous regimens in varying order to each of five women with hypothalamic amenorrhea and presumed endogenous GnRH deficiency. Mean serum levels of GnRH were similar during the pulsatile and continuous regimens. All women ovulated during the pulsatile regimen (progesterone, greater than 31.8 nmol/L (10 ng/mL); none ovulated during the continuous regimen. Compared to pretreatment levels, FSH and estradiol, as measured by RIA, and LH, as measured by bioassay, increased significantly during the pulsatile GnRH regimen, but not during the continuous regimen. However, LH and alpha-subunit, as measured by RIA, increased significantly during both continuous and pulsatile GnRH administration. We conclude that a pulsatile pattern of GnRH is essential to normal functioning of the human female reproductive axis. Continuous administration of GnRH, producing mean serum levels of the peptide indistinguishable from those found during pulsatile administration, stimulates some rise in a nonbioactive form of radioimmunoassayable LH-like material and alpha-subunit, but does not stimulate bioactive LH, FSH, estradiol, or progesterone and does not lead to ovulation.     

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.     

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.     

Ovulation induction with a single-blind treatment regimen comparing naltrexone, placebo and clomiphene citrate in women with secondary amenorrhea.

Secondary amenorrhea is often associated with emotional stress, weight loss, eating disorders or polycystic ovary-like disease. Involvement of the endogenous opioids in the pathophysiology of hypothalamic amenorrhea, by inhibition of hypothalamic GnRH secretion, has been demonstrated in some cases. Chronic blockade of the endogenous opioids with the long-acting opioid antagonist naltrexone could result in increased gonadotropin secretion and ovulation induction in these cases. A single-blind ovulation induction protocol comparing naltrexone, placebo and clomiphene citrate was evaluated in eight patients with secondary amenorrhea. Naltrexone proved not to be more effective than placebo in our study. Only one patient ovulated on naltrexone, one on placebo and four on clomiphene citrate. The latter therapy caused a better endocrine response. In conclusion, although ovulation could be incidentally induced by naltrexone, this drug did not appear to be more successful than placebo and clomiphene citrate for ovulation induction in this population of patients.     

Altered neuroendocrine regulation of gonadotropin secretion in women distance runners

We tested the hypothesis that the neuroendocrine control of gonadotropin secretion is altered in certain women distance runners with secondary amenorrhea. To this end, we quantitated the frequency and amplitude of spontaneous pulsatile LH secretion during a 24-h interval in nine such women. The ability of the pituitary gland to release LH normally was assessed by administration of graded bolus doses of GnRH during the subsequent 8 h. Compared to normally menstruating women, six of nine amenorrheic distance runners had a distinct reduction in spontaneous LH pulse frequency, with one, three, six, five, four, or two pulses per 24 h (normal, 8-15 pulses/24 h). This reduction in LH pulse frequency occurred without any significant alterations in plasma concentrations of estradiol and free testosterone or 24-h integrated serum concentrations of LH, FSH, or PRL. Moreover, in long-distance runners, the capacity of the pituitary gland to release LH was normal or accentuated in response to exogenous pulses of GnRH. In the six women athletes with diminished spontaneous LH pulsatility, acute ovarian responsiveness also was normal, since serum estradiol concentrations increased normally in response to the GnRH-induced LH pulses. Although long-distance runners had significantly lower estimated percent body fat compared to control women, specific changes in pulsatile gonadotropin release did not correlate with degree of body leanness. In summary, certain long-distance runners with secondary amenorrhea or severe oligomenorrhea have unambiguously decreased spontaneous LH pulse frequency with intact pituitary responsiveness to GnRH. This neuroendocrine disturbance may be relevant to exercise-associated amenorrhea, since pulsatile LH release is a prerequisite for cyclic ovarian function. We speculate that such alterations in pulsatile LH release in exercising women reflect an adaptive response of the hypothalamic pulse generator controlling the intermittent GnRH signal to the pituitary gland. The basis for amenorrhea in the remaining runners who have normal pulsatile properties of LH release is not known.     

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.     

Gonadotropin-releasing activity of alpha-melanocyte-stimulating hormone in normal subjects and in subjects with hypothalamic-pituitary dysfunction

The gonadotropin-releasing activity of synthetic alpha MSH, previously found in normal men, was evaluated in women with different hormonal environments and in patients with acyclic gonadotropin release due to hypothalamic-pituitary dysfunction. alpha MSH (2.5 mg, iv) administered as either a single or two repeated pulses (at 2-h intervals) elicited unequivocal pituitary release of LH in normal women during the luteal phase and midcycle surge and in patients with functional hypothalamic amenorrhea, hyperprolactinemic amenorrhea, and polycystic ovary syndrome. Concomitant release of LH and FSH occurred only in polycystic ovarian syndrome patients and normal men. alpha MSH had no discernible effect on gonadotropin release in women during the early and late follicular phases of the cycle, in postmenopausal women, and in patients with isolated gonadotropin deficiency, even after pulsatile GnRH priming. The present observations confirm and extend our earlier finding that alpha MSH possesses gonadotropin-releasing activity in men and indicate that alpha MSH has similar properties in women with progesterone- and androgen-dominated environments or with specific types of hypothalamic-pituitary dysfunction marked by attenuated GnRH-LH release.     

Hypopituitarism

Hypopituitarism is the partial or complete insufficiency of anterior pituitary hormone secretion and may result from pituitary or hypothalamic disease. The reported incidence (12–42 new cases per million per year) and prevalence (300–455 per million) is probably underestimated if its occurrence after brain injuries (30–70% of cases) is considered. Clinical manifestations depend on the extent of hormone deficiency and may be non specific, such as fatigue, hypotension, cold intolerance, or more indicative such as growth retardation or impotence and infertility in GH and gonadotropin deficiency, respectively. A number of inflammatory, granulomatous or neoplastic diseases as well as traumatic or radiation injuries involving the hypothalamic-pituitary region can lead to hypopituitarism. Several genetic defects are possible causes of syndromic and non syndromic isolated/multiple pituitary hormone deficiencies. Unexplained gonadal dysfunctions, developmental craniofacial abnormalities, newly discovered empty sella and previous pregnancy-associated hemorrhage or blood pressure changes may be associated with defective anterior pituitary function. The diagnosis of hypopituitarism relies on the measurement of basal and stimulated secretion of anterior pituitary hormones and of the hormones secreted by pituitary target glands. MR imaging of the hypothalamo-pituitary region may provide essential information. Genetic testing, when indicated, may be diagnostic. Secondary hypothyroidism is a rare disease. The biochemical diagnosis is suggested by low serum FT4 levels and inappropriately normal or low basal TSH levels that do not rise normally after TRH. L-thyroxine is the treatment of choice. Before starting replacement therapy, concomitant corticotropin deficiency should be excluded in order to avoid acute adrenal insufficiency. Prolactin deficiency is also very rare and generally occurs after global failure of pituitary function. Prolactin deficiency prevents lactation. Hypogonadotropic hypogonadism in males is characterized by low testosterone with low or normal LH and FSH serum concentrations and impaired spermatogenesis. Hyperprolactinemia as well as low sex hormone binding globulin concentrations enter the differential diagnosis. Irregular menses and amenorrhea with low serum estradiol concentration (<100 pmol/l) and normal or low gonadotropin concentrations are the typical features of hypogonadotropic hypogonadism in females. In post menopausal women, failure to detect high serum gonadotropin values is highly suggestive of the diagnosis. In males, replacement therapy with oral or injectable testosterone results in wide fluctuations of serum hormone levels. More recently developed transdermal testosterone preparations allow stable physiological serum testosterone levels. Pulsatile GnRH administration can be used to stimulate spermatogenesis in men and ovulation in women with GnRH deficiency and normal gonadotropin secretion. Gonadotropin administration is indicated in cases of gonadotropin deficiency or GnRH resistance but is also an option, in alternative to pulsatile GnRH, for patients with defective GnRH secretion.     

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.     

Intravenous administration of pulsatile gonadotropin-releasing hormone in hypothalamic amenorrhea: effects of dosage

Eighteen women with well characterized hypothalamic amenorrhea underwent 30 cycles of pulsatile GnRH treatment in an effort to examine the role of GnRH dosage in pituitary and ovarian responses. GnRH was administered iv at 2 doses (25 and 100 ng/kg bolus) at a physiological range of frequencies (90 and 60 min) in the follicular phase of the induced cycles. After demonstration of ovulation by ultrasound and clinical parameters, the frequency of GnRH administration was progressively slowed from every 60 min to every 90 min and then to every 240 min to mimic the slowing of endogenous LH secretion that occurs during the luteal phase in normal women. The results of these induced cycles were compared to those of 62 ovulatory cycles from normal women. Overall clinical and biochemical results revealed the following. Patients receiving doses of 25 ng/kg GnRH successfully ovulated only 80% of the time, with recruitment of a single dominant follicle. Two of 5 patients became pregnant. Peak estradiol levels were significantly lower than normal [261 +/- 33 (+/- SE) vs. 342 +/- 11 pg/ml, respectively; P less than 0.02]. Integrated luteal phase progesterone production was also significantly reduced in the 25 ng/kg group compared to normal (78 +/- 17 vs. 145 +/- 8 ng/ml/entire luteal phase, respectively; P less than 0.02). All women receiving bolus doses of 100 ng/kg GnRH ovulated; maturation of multiple follicles occurred in 5 of 20 cycles, and 6 of 7 women conceived. Peak estradiol values were significantly higher than those in either normal women or the 25 ng/kg group (478 +/- 48 pg/ml; P less than 0.02 for both), with integrated luteal phase progesterone levels significantly higher than those in patients receiving the 25 ng/kg dose (196 +/- 25 ng/ml/luteal phase; P less than 0.02). This study demonstrates that ovulation and fertility can be achieved with a physiological frequency regimen of pulsatile GnRH administration using bolus doses of both 25 and 100 ng/kg in women with hypothalamic amenorrhea; the 25 ng/kg dose of GnRH may represent a threshold of stimulation of the pituitary-ovarian axis and recreates cycles with an inadequate luteal phase; and a 100 ng/kg dose of GnRH may well cause a supraphysiological stimulation of the pituitary-gonadal axis.     

Induction of ovulation by pulsatile gonadoliberin administration. Indications and limits

With its simplicity, innocuity and efficacy, pulsatile GnRH administration constitutes a considerable advance in ovulation induction techniques. Its purpose is not to replace classic methods like Clomiphene Citrate, gonadotropins or dopaminergic agonists, but to complement them. While the choice of administration route, IV vs SC is still controversial, the efficacy depends mainly on the selection of the patients susceptible of benefiting from this therapy. Low gonadotropic activity hypothalamic amenorrhea remains the best indication for pulsatile GnRH, as substantiated by the results published over the last 10 years. The other anovulation causes, including PCO-S, are more disputable indications, and prospective studies involving homogeneous populations are necessary to assess the true standing of GnRH in such indications.     

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.     

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.     

Further delineation of hypothalamic dysfunction responsible for menopausal hot flashes

An association exists between pulsatile LH release and hot flashes (HFs). To further delineate the hypothalamic mechanism(s) responsible for HF, the basal levels and pulsatile release of LH, FSH, estradiol, and estrone and the rate of occurrence of HFs (measured objectively) were evaluated in patients with a defect of GnRH secretion [isolated gonadotropin deficiency (IGD)], patients with abnormalities of afferent input to GnRH neurons [hypothalamic amenorrhea (HA)], and postmenopausal women with severe HFs. Patients with IGD had received estrogens, which were discontinued before study. Patients with HA had experienced regular menses before disease onset, which followed emotional stress or weight loss. Studies were limited to HA patients with estrogen levels in the postmenopausal range. Pulsatile LH release was absent in patients with IGD and was absent or greatly reduced in women with HA. Objectively measured and subjectively experienced HFs occurred in IGD but not in HA patients. These results suggest that HFs are not an obligatory consequence of low endogenous estrogen levels and that the absence of episodic LH and GnRH release (IGD) does not influence the occurrence of HFs. It is possible that the dysfunction of afferent input to GnRH neurons in HA somehow prevents HFs in these women with low endogenous estrogen secretion.     

X-linked adrenal hypoplasia congenita: a mutation in DAX1 expands the phenotypic spectrum in males and females

X-linked adrenal hypoplasia congenita (AHC) is a disorder associated with primary adrenal insufficiency and hypogonadotropic hypogonadism (HH). The gene responsible for X-linked AHC, DAX1, encodes a member of the nuclear hormone receptor superfamily. We studied an extended kindred with AHC and HH in which two males (the proband and his nephew) were affected with a nucleotide deletion (501delA). The proband's mother, sister, and niece were heterozygous for this frameshift mutation. At age 27 yr, after 7 yr of low dose hCG therapy, the proband underwent a testicular biopsy revealing rare spermatogonia and Leydig cell hyperplasia. Despite steadily progressive doses of hCG and Pergonal administered over a 3-yr period, the proband remained azoospermic. The proband's mother, sister (obligate carrier), and niece all had a history of delayed puberty, with menarche occurring at ages 17-18 yr. Baseline patterns of pulsatile gonadotropin secretion and gonadotropin responsiveness to exogenous pulsatile GnRH were examined in the affected males. LH, FSH, and free alpha-subunit were determined during 12.5-24 h of frequent blood sampling (every 10 min). Both patients then received pulsatile GnRH (25 ng/kg) sc every 2 h for 6-7 days. Gonadotropin responses to a single GnRH pulse iv were monitored daily to assess the pituitary responsiveness to exogenous GnRH. In the proband, FSH and LH levels demonstrated a subtle, but significant, response to GnRH over the week of pulsatile GnRH therapy. Free alpha-subunit levels demonstrated an erratic pattern of secretion at baseline and no significant response to pulsatile GnRH. We conclude that 1) affected males with AHC/HH may have an intrinsic defect in spermatogenesis that is not responsive to gonadotropin therapy; 2) female carriers of DAX1 mutations may express the phenotype of delayed puberty; and 3) although affected individuals display minimal responses to pulsatile GnRH, as observed in other AHC kindreds, subtle differences in gonadotropin patterns may nevertheless exist between affected individuals within a kindred.     

Progesterone stimulates luteinizing hormone secretion by acting directly on the pituitary.

To determine if progesterone (P) does affect gonadotropin secretion by acting directly on the pituitary, six women with hypothalamic gonadotropin deficiency were studied. They were treated with 17 beta-estradiol (E2; 2 mg/day, orally) to induce P receptors and maintain constant plasma E2 levels during two 15-day periods separated by 1 month. GnRH was administered iv at a dose of 10 microgram/pulse every 90 min during the last 5 days of E2 treatment. Either P (400 mg/day) or a placebo was administered intravaginally in a cross-over randomized design during the 5 days of pulsatile GnRH therapy. A baseline study of pulsatile LH secretion was performed, with sampling performed every 10 min for 8 h. The sampling was then repeated on day 15 of each study period at the end of pulsatile GnRH administration. Plasma levels of E2 and P were measured every day during the 5 days of either GnRH and P or GnRH and placebo treatment. In the six patients, the observed apulsatile pattern of LH during the baseline study confirmed the diagnosis of complete gonadotropin deficiency. Plasma E2 levels were not significantly different at the time of each pulse analysis (288 +/- 61 vs. 252 +/- 77 pmol/L). The plasma P level achieved with the vaginal pessaries was 22 +/- 5 nmol/L. P treatment resulted in all cases in a significant increase in the mean plasma LH level (5.2 +/- 0.9 vs. 3.6 +/- 0.7 IU/L after GnRH plus placebo; P less than 0.001). Furthermore, LH pulse amplitude was significantly increased by P compared to placebo (3.1 +/- 0.3 vs. 1.4 +/- 0.1 IU/L, respectively; P less than 0.01). Mean plasma FSH levels were significantly increased by GnRH regardless of whether P or placebo was present. In conclusion, these data indicate that a short exposure to physiological levels of P in the range of early luteal phase levels has a stimulatory effect on LH secretion by acting directly at the pituitary level.     

Pulsatile gonadotropin secretion after discontinuation of long term gonadotropin-releasing hormone (GnRH) administration in a subset of GnRH-deficient men

Normal pituitary and gonadal function can be maintained with long term pulsatile GnRH administration in men with idiopathic hypogonadotropic hypogonadism (IHH), and both pituitary and gonadal priming occur during the process of GnRH-induced sexual maturation. Still, the long term effects of discontinuing GnRH therapy in IHH men have not been examined. Therefore, we evaluated the patterns of gonadotropin and alpha-subunit secretion before and after a prolonged period of pulsatile GnRH administration in 10 IHH men. Before exogenous GnRH stimulation, no patient had any detectable LH pulsations. In 6 of these men, who were typical of most of our IHH patients (group I), no LH pulsations were detectable after cessation of GnRH administration. However, in the other 4 men (group II), LH pulsations were easily detectable despite cessation of exogenous GnRH stimulation, and the amplitude (9.3 +/- 3.5 IU/L) and frequency (13.8 +/- 1.7 pulses/day) of these LH pulses were similar to those in 20 normal men (10.6 +/- 0.7 IU/L and 11.0 +/- 0.7 pulses/day). Three of these 4 men in group II maintained normal serum testosterone levels after discontinuation of GnRH delivery. To determine if there were any characteristics that might be useful in predicting which IHH men could maintain normal pituitary-gonadal function after long term GnRH administration, we evaluated various clinical and hormonal parameters at the time of initial presentation. Mean alpha-subunit levels (P less than 0.01) and alpha-subunit pulse amplitude (P less than 0.02) were significantly higher in the group II than the group I men, suggesting that the group II patients had partial, rather than complete, deficiency of endogenous GnRH secretion. None of the other parameters that were assessed distinguished the two groups. We conclude that gonadotropin and sex steroid levels return to their pretreatment state in the majority of IHH men when long term GnRH administration is discontinued. Normal pituitary-gonadal function can be maintained after discontinuation of long term GnRH administration in a rare subset of IHH men who present with higher levels of alpha-subunit. We hypothesize that these latter IHH men have an incomplete GnRH deficiency and that long term exogenous GnRH administration induces pituitary and gonadal priming, which subsequently enables them to sustain normal pituitary and gonadal function in response to their own enfeebled GnRH secretion.     

Hypogonadotropic disorders in men and women: diagnosis and therapy with pulsatile gonadotropin-releasing hormone

Hypogonadotropic hypogonadism (HH) is a clinical syndrome occurring in both sexes which has long puzzled clinicians due to the apparent paradox of nonfunctioning gonads in the face of normal or only slightly lowered levels of circulating gonadotropins. Using frequent sampling of gonadotropin levels as an index of hypothalamic GnRH secretion, we have examined the hypothesis that this group of disorders represents a spectrum of abnormal patterns of the pulsatile release of endogenous GnRH. After a broad, normative data base was established in both men and women for purposes of comparison, it appears that quantifiable abnormalities of GnRH secretion are discernible in both males and females with HH. These abnormalities include a total absence of GnRH secretion, defects of the amplitude and frequency of its secretion, and altered bioactivity of the gonadotropins released. In addition, physiological regimens of hypothalamic replacement therapy with exogenous GnRH, which are fashioned to mimic the normal frequency of endogenous GnRH secretion, result in complete normalization of reproductive function and fertility in hypogonadotropic subjects of both sexes. Thus, the heterogeneous nature of HH, as well as its favorable clinical and biochemical responses to GnRH, suggest that the basic defect in this family of disorders involves a partial or complete inability to synthesize and/or release GnRH from the hypothalamus in a manner compatible with physiological reproductive function. Conversely, these findings imply that maintenance of a physiological amplitude and frequency of endogenous GnRH secretion appear to be essential for normal reproductive function.     

A modified hMG-GnRH method for the induction of ovulation in infertile women with severe hypogonadotropic amenorrhea

The objective of this study was to compare, in infertile women suffering from severe hypogonadotropic amenorrhea, the therapeutic utility and the incidence of complications arising from fertility treatment by the conventional human menopausal gonadotropin/human chorionic gonadotropin (hMG-hCG) method, the hMG step-down method, the sequential hMG/gonadotropin-releasing hormone (GnRH) method and a new, modified hMG-GnRH method that has been developed by us. In the step-down method, the daily dose of hMG was decreased from 150 IU to 75 IU when the follicle diameter reached 11-13 mm. In the sequential hMG-GnRH, hMG injection was switched to pulsatile GnRH administration (20 microg/120 min SC), when the follicle diameter reached 11-13 mm. In our new modified hMG-GnRH, pulsatile GnRH was injected together with hMG. Daily hMG was stopped and the GnRH dosage was changed from 10 microg to 20 microg when the follicle diameter reached 11-13 mm. Initially, the three established methods were applied randomly to treat 34 cycles in 20 women; and subsequently, five patients who failed to conceive following treatment by sequential hMG-GnRH were then treated by the modified hMG-GnRH method. More than eight growing follicles and multiple pregnancies were observed during treatment by the conventional method. The incidence of ovarian hyperstimulation syndrome (OHSS) was 25.7% with the conventional method, 20.0% with the step-down method and 0% with the sequential hMG-GnRH method; however, the rate of ovulation was only 50% with the sequential hMG-GnRH method. By contrast, with the modified hMG-GnRH method, less than three growing follicles occurred in 81.8% of patients, there was a 100% rate of ovulation, and neither OHSS nor multiple pregnancies were observed. Moreover, the modified hMG-GnRH method induced pregnancy in 3 out of 5 patients. These data indicate that this new method is favorable for the treatment of severe hypogonadotropic amenorrhea.     

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.