Hormonal regulation of androgen-binding protein in the rat.

Effects of gonadotropins and gonadal steroids on androgen-binding protein (ABP) production by the testis and its secretion into the blood and transport into the epididymis were studied in 20- and 30-day-old rats. These animals had been treated with hCG, FSH, the Nal-Glu GnRH antagonist [Ac-D2Nal1,D4ClDPhe2,D3Pal3,Arg5,DGlu6(AA) ,DAla10]LHRH (antagonist), testosterone propionate, or estradiol benzoate, alone or in combination, for 10 days before assessment of ABP. Antagonist administration suppressed the testicular content (nanograms per organ) of ABP to below control (untreated) levels in both age groups. When hCG or testosterone was given along with the antagonist, they overcame the effect of the antagonist, and the resultant ABP values exceeded untreated control levels in both the 20- and 30-day-old rats. Treatment of rats with these hormones in the absence of the GnRH antagonist also elevated the ABP content of the testis above that of untreated controls. FSH administered with antagonist was able to prevent the antagonist-induced suppression of testicular ABP content. When rats were treated with FSH alone, the content of ABP in the testis was increased above untreated control levels in the 30-day-old group, but not in the 20-day-old group. The simultaneous administration of FSH and hCG did not result in an increase in testicular ABP content above that caused by hCG or testosterone alone. The increase in the ABP content of the testis caused by FSH administration was only about one sixth that caused by hCG or testosterone. Since testosterone or hCG, even in the presence of antagonist, was able to maximally stimulate ABP production by the testis of both age groups, we conclude that testosterone is the major in vivo regulator of its synthesis. Only combined treatment with hCG and FSH was able to increase transport of ABP into the epididymis of 20-day-old rats. All treatments that increased the testicular content of ABP in the 30-day-old rats also increased its transport into the epididymis. Treatments that drastically reduced the content of ABP in the testis of 20-day-old rats (antagonist, estradiol, estradiol plus antagonist) also reduced ABP secretion into the serum. Only treatment with estradiol reduced the secretion of ABP into the serum of 30-day-old rats. None of the treatments increased the ABP secretion into the bloodstream above untreated control levels.

Gonadotropin-releasing hormone receptor gene expression in human ovary and granulosa-lutein cells.

GnRH regulates gonadotropin biosynthesis and release in the anterior pituitary via specific receptors. Although extrapituitary expression and action of GnRH have been shown in some species, in the human it is not clear whether GnRH has a peripheral action. In this study we sought to determine whether the human ovary expresses GnRH receptor (GnRHR) messenger ribonucleic acid (mRNA). Ovarian tissues from 11 women (32-61 yr old) and granulosa-lutein (GL) cells purified from follicular aspirates of 51 women undergoing oocyte retrieval for in vitro fertilization were analyzed by ribonuclease protection assay and reverse transcriptase-polymerase chain reaction (RT-PCR). Human pituitaries, lymphocytes, and placenta were also studied. Measurable levels of GnRHR mRNA were found by ribonuclease protection assay in 2 of 10 ovaries, in 2 of 4 GL cells preparations from women whose ovarian hyperstimulation involved a GnRH agonist, in GL cells from 3 women whose ovarian hyperstimulation involved a GnRH antagonist, and in human pituitaries. Relative to the total amount of RNA analyzed, the level of GnRHR mRNA was about 200-fold lower in the ovary than in the pituitary. A sequence of 314 basepairs of GnRHR mRNA was amplified by RT-PCR in the pituitary, in 9 of 10 ovaries, and in 4 of 5 GL cell preparations. No message could be amplified in human lymphocytes, and placental specimens showed a weak signal. The relative GnRHR mRNA levels in GL cells from 13 women analyzed by quantitative RT-PCR showed a wide range of individual differences. These results suggest that GnRHR mRNA is expressed in GL cells and the human ovary across different functional stages, implying that multiple ovarian compartments may express GnRH receptors. The administration of GnRH analogs may have a further direct action on the human ovary.

Regulation of pituitary glycoprotein alpha-subunit secretion after administration of a luteinizing hormone-releasing hormone antagonist in normal men.

Pituitary glycoprotein hormones are composed of two different subunits, the alpha- and beta-subunits. The alpha-subunit is common to all FSH, LH, and TSH, while the beta-subunit is specific for each of these hormones. We studied the effects of a potent LHRH antagonist on alpha-subunit and LH secretion in normal men. The LHRH antagonist Nal-Glu, ([Ac-D2Nal1,D4ClPhe2,D3Pal3,Arg5,DGlu6(AA) ,Ala10]LHRH), was given (10 mg daily) as one injection of 5 mg every 12 h. Blood samples were drawn every 24 h, and on days 1 and 7 a day curve was established by drawing hourly blood samples for 26 h. Mean serum alpha-subunit levels decreased progressively (P less than 0.001) from 2.9 +/- 0.49 micrograms/L at baseline to a nadir of 1.4 +/- 0.27 micrograms/L on day 8. In contrast, mean immunoreactive LH (IR-LH) levels decreased rapidly from 3.2 +/- 0.6 U/L at baseline to 0.9 +/- 0.08 U/L on day 2 and remained suppressed (P less than 0.001) throughout the treatment period. On day 1 after the administration of Nal-Glu mean alpha-subunit levels decreased, although not significantly (P = 0.054), from 3.0 +/- 0.6 micrograms/L at baseline to a nadir of 2.0 +/- 0.3 micrograms/L at 17 h. alpha-Subunit remained at this level for the remainder of day 1. On day 7, however, the baseline serum alpha-subunit level was 1.5 +/- 0.3 micrograms/L, significantly suppressed (P less than 0.01) compared to the level on day 1, and no further decrease was seen after administration of Nal-Glu. IR-LH on day 1 before the first injection of 5 mg Nal-Glu was 3.5 +/- 0.8 U/L. Then, IR-LH levels decreased significantly (P less than 0.001) to a nadir of 0.9 +/- 0.1 U/L and remained at this level throughout day 1. IR-LH levels on day 7 were at or below 1.0 U/L throughout the sampling period. These results indicate that alpha-subunit secretion can be partially suppressed after chronic administration of a LHRH antagonist. Furthermore, LH serum levels dissociate from those of pituitary glycoprotein alpha-subunit after administration of LHRH antagonist analogs.

Defective regulation of glycoprotein free alpha-subunit in males with isolated gonadotropin-releasing hormone deficiency--a clinical research center study.

During long term replacement with a GnRH regimen that restores their gonadotropin and sex steroid levels to normal, men with idiopathic hypogonadotropic hypogonadism (IHH) exhibit excessive secretion of pituitary free alpha-subunit (FAS). To characterize further the dose and duration of exogenous GnRH required to elicit this response, FAS, LH, FSH, and testosterone were determined during the first 8 weeks of GnRH administration in 10 men with IHH. The GnRH dose was increased stepwise every 2 weeks from 5 to 100 ng/kg every 2 h. Hormonal responses were compared with normative data for both pubertal boys and adult men. Low baseline levels of LH (mean +/- SEM, 0.9 +/- 0.03 IU/L), FSH (2.5 +/- 0.4 IU/L), FAS (148 +/- 21 ng/L), and testosterone (2.5 +/- 0.3 nmol/L) increased progressively after GnRH replacement. Mean FAS levels and pulse amplitudes significantly exceeded those in normal adult men by 4-6 weeks when their LH responses to GnRH administration remained below adult norms. By week 8 (50 ng GnRH/kg every 2 h), mean levels of LH, FSH, and FAS (13.7 +/- 2.1 IU/L, 15.4 +/- 4.0 IU/L, 627 +/- 75 ng/L, respectively) significantly exceeded adult male concentrations (P < 0.03). However, mean LH and FSH concentrations were not significantly different from midpubertal controls, in whom FAS levels were comparable to those in normal adults, verifying the excessive nature of FAS secretion relative to intact gonadotropins in the IHH patients. As this imbalance between FAS and dimeric gonadotropin secretion was established early in the current study when low doses of GnRH presumably resulted in low levels of receptor occupancy in vivo, it does not appear to result from partial pituitary desensitization induced by pharmacological GnRH stimulation. Rather, it appears to represent an inherent property of the GnRH-deficient state that is unmasked when GnRH input to the pituitary is restored. Further work will be necessary to elucidate the mechanism of this apparent defect in FAS regulation in GnRH-deficient men.

The changing ratio of serum bioactive to immunoreactive follicle-stimulating hormone in normal men following treatment with a potent gonadotropin releasing hormone antagonist.

Using a recently developed granulosa cell aromatase bioassay (GAB), we measured serum bioactive follicle-stimulating hormone (bio-FSH) levels in 5 normal men after administration of a potent GnRH antagonist. Although only minimal suppression of immunoreactive FSH (immuno-FSH) was detected during administration of 20 mg of the antagonist, [N-Ac-D-Nal(2)1,D-pCl-Phe2,D-Trp3,D-h(Arg(Et2)6,D-Ala10]GnRH , pronounced inhibition (79 to 89%) of bio-FSH levels occurred. Concomitantly, the ratio of bio- to immuno-FSH levels dramatically decreased within 6 h after antagonist administration. These data reinforce earlier expectations that GnRH antagonists might be potential male contraceptives and provide the first report of changes in circulating bio- to immuno-FSH levels. The GAB assay will facilitate future studies on the biochemical mechanisms by which GnRH antagonists induce changes in the bioactivity of circulating FSH.

New technique for quantitation of pituitary adenoma size: use in evaluating treatment of gonadotroph adenomas with a gonadotropin-releasing hormone antagonist.

Because administration for 1 week of the GnRH antagonist Nal-Glu GnRH had been shown to decrease FSH secretion from supranormal to normal in men with gonadotroph adenomas, we investigated the effect of prolonged administration of Nal-Glu on the size of gonadotroph adenomas. To quantitate the effect of Nal-Glu GnRH on gonadotroph adenoma size, we first developed a technique for calculating adenoma volume. The technique involved collecting magnetic resonance (MR) imaging data from each adenoma at 1-mm slice intervals in the coronal, axial, and sagittal views and using the Softvu computer program to calculate adenoma volume from the MR data. The precision of this technique, as judged by the coefficients of variation of the calculations of the same view of the same study three times, was 1.7%, 1.0%, and 1.0% for each of three studies. When Nal-Glu GnRH (5 mg, sc, every 12 h) was self-administered for 3-12 months to five men with gonadotroph adenomas and supra-normal serum FSH concentrations, the serum FSH concentrations decreased to normal or below normal for the entire treatment period. Adenoma size, however, did not change during treatment in any of the five men. We conclude that calculating pituitary adenoma volume from MR data using the Softvu computer program is a highly reproducible technique, but that Nal-Glu GnRH is not an effective treatment for reducing gonadotroph adenoma size. The failure of Nal-Glu to reduce adenoma size despite its success in reducing FSH secretion suggests that FSH secretion from gonadotroph adenomas is dependent on endogenous GnRH, but growth of gonadotroph adenomas is not.

Gonadotroph adenoma in a premenopausal woman secreting follicle-stimulating hormone and causing ovarian hyperstimulation.

The clinical manifestations of gonadotroph adenomas are almost always neurological, consequences of their large size, and are rarely endocrinological. We report an exception, a 39-yr-old woman whose gonadotroph adenoma caused supranormal serum concentrations of FSH, which resulted in the development of multiple ovarian cysts, persistent elevation of her serum estradiol concentration, and endometrial hyperplasia. She initially presented because of amenorrhea at age 30 yr and was treated for an intrasellar mass by transsphenoidal surgery at age 31 yr and again at age 36 yr. Before and after the second operation she had persistently supranormal plasma estradiol concentrations (> 1840 pmol/L) and endometrial hyperplasia. When she was evaluated at age 39 yr, transvaginal ultrasound showed multiple ovarian cysts and endometrial thickening. Her plasma estradiol level was markedly supranormal (2160 pmol/L), FSH was mildly supranormal (17.8 IU/L), and alpha-subunit was markedly supranormal (23.3 micrograms/L). Characteristic of gonadotroph adenomas, her LH beta level increased by 69% in response to TRH. Neither FSH nor alpha-subunit decreased in response to administration of the GnRH antagonist, Nal-Glu-GnRH (5 mg/12 h for 4 weeks). Excised adenoma tissue exhibited morphological features of a gonadotroph adenoma. This patient appears to be unique, in that her gonadotroph adenoma caused slightly, but persistently, supranormal concentrations of FSH, which caused ovarian stimulation, including supranormal plasma estradiol concentrations, multiple ovarian cysts, and endometrial hyperplasia. We propose that gonadotroph adenomas be considered in the differential diagnosis of patients who have this constellation of abnormalities.

Single subcutaneous doses of a luteinizing hormone-releasing hormone antagonist suppress serum gonadotropin and testosterone levels in normal men.

The ability of single doses of a LHRH antagonist [Ac-delta 3Pro1, 4F-D-Phe2, D-Trp3,6]LHRH (4F-antagonist) to suppress serum gonadotropin and testosterone levels was studied in six normal men. The 4F-antagonist was given sc at four doses: 40, 80, 160, and 320 micrograms/kg body weight. Serum immunoreactive LH, FSH, and testosterone and bioactive LH were measured at intervals for the subsequent 18 h. Serum LH decreased rapidly by (mean +/- SE) 39.7 +/- 2.7%, 41.6 +/- 5.4%, 45.5 +/- 4.7%, and 45.3 +/- 5.4% after each of the four doses. The mean number of LH pulses and their amplitude decreased after each dose and remained suppressed for at least 6 h. After each of the four doses, mean serum FSH levels decreased by 20.0 +/- 4.1%, 33.8 +/- 6.8%, 25.8 +/- 3.6%, and 33.3 +/- 5.7%, and mean serum testosterone levels decreased by 47.7 +/- 7.3%, 55.6 +/- 10.5%, 58.2 +/- 10.8%, and 76.0 +/- 6.0%. Serum testosterone remained low for at least 18 h after the two higher doses. LH bioactivity and the ratio of bioactive LH to immunoreactive LH decreased in all subjects, especially after higher doses of the 4F-antagonist. No side effects or adverse reactions occurred after 4F-antagonist administration, and toxicology studies were negative. These results demonstrate that a single sc injection of this potent LHRH antagonist inhibits the pituitary-gonadal axis in normal men.

Mode of suppression of pituitary and gonadal function after acute or prolonged administration of a luteinizing hormone-releasing hormone antagonist in normal men.

LHRH antagonists compete with endogenous LHRH for binding to receptors on pituitary gonadotrophs and thereby inhibit gonadotropin secretion and, consequently, gonadal function. We studied the pituitary and gonadal suppression following single doses and short term administration (1-3 weeks) of a recently developed LHRH antagonist in normal men. First, the antagonist Nal-Glu ([Ac-D2Nal1, D4ClPhe2,D3Pal3,Arg5,DGlu6(AA),DAla10]LHRH ), was given as a single sc injection to five normal men at three dose levels of 1, 5, and 20 mg (study I). Serum FSH, immunoreactive LH (IR-LH), bioactive LH (bio-LH), testosterone, and estradiol were measured before and at frequent intervals for 48 h after Nal-Glu administration. Mean serum FSH decreased (P less than 0.001) by 28.9 +/- 5.4% (+/- SE), 38.2 +/- 7.9%, and 44.5 +/- 3.6% after the 1-, 5-, and 20-mg doses, respectively. Mean serum IR-LH decreased (P less than 0.001) by 39.0 +/- 13.8%, 53.2 +/- 10.0%, and 53.1 +/- 14.4% after the three doses. Serum bio-LH levels and the ratio of bio-LH/IR-LH decreased (P less than 0.001) after the 20-mg dose by 87.8% and 78.5%, respectively. Serum testosterone levels decreased (P less than 0.001) more than 78.5% after all Nal-Glu doses. The duration of testosterone suppression, but not the nadir reached, was dose dependent (P = 0.012). Serum estradiol levels also decreased (P less than 0.001), but the rate of decrease was slower than that of serum testosterone. The apparent plasma disappearance half-life of Nal-Glu after administration of 5 mg was 12.8 +/- 2.7 h. The Nal-Glu antagonist also was given daily as a single sc injection of 5 mg to eight normal men for 21 days (study II) or twice daily to five men for 7 days (study III). In study II, serum FSH, IR-LH, bio-LH, testosterone, estradiol, and 17-hydroxy-progesterone were measured daily, immediately before the next injection, and on days 1, 7, and 21 in frequent blood samples drawn for 24 h. The mean serum testosterone level in study II decreased (P less than 0.001) from 17.6 +/- 2.2 to 4.1 +/- 1.0 nmol/L on day 1, increased (P less than 0.05) between days 2 and 8, and then progressively decreased to below 2 nmol/L from day 18 until 24 h after the end of the study. Serum FSH, IR-LH, and bio-LH levels paralleled those of testosterone.(ABSTRACT TRUNCATED AT 400 WORDS)

Abrogation by a potent gonadotropin-releasing hormone antagonist of the estrogen/progesterone-stimulated surge-like release of luteinizing hormone and follicle-stimulating hormone in postmenopausal women.

In both the rodent and primate, administration of progesterone elicits an acute surge-like release of LH in the setting of prior estrogen treatment. Whether these facilitative effects of estrogen and progesterone on gonadotropin secretion reside at pituitary or hypothalamic loci is not known. To further investigate the mechanisms by which estrogen combined with progesterone amplifies gonadotropin secretion, we studied the responses of seven estrogen-primed postmenopausal women to progesterone administration with or without cotreatment with a potent GnRH antagonist, [Ac-D2Nal1,D4ClPhe2,D3Pal3,Arg5,DGlu6(AA), DAla10]GnRH. Repetitive blood sampling for the later measurement of serum concentrations of LH, FSH, and PRL was begun 4 h before the administration of progesterone and continued for 36 h. We observed that progesterone administration after 72 h of priming with ethinyl estradiol resulted in a surge-like release of LH and FSH in all subjects. Concomitant administration of the GnRH antagonist abolished the surge-like release of both gonadotropins in all subjects. In contrast, administration of the antagonist had no effect on PRL release. These results indicate that endogenous GnRH action is an obligatory component of the progesterone-induced surge-like release of both gonadotropic hormones in the estrogen-primed human.

Maintenance of the ratio of bioactive to immunoreactive follicle-stimulating hormone in normal men during chronic luteinizing hormone-releasing hormone agonist administration.

Chronic administration of LHRH agonist analogs to humans reduces gonadal function through pituitary desensitization. Serum immunoreactive gonadotropin levels are modestly reduced, whereas serum bioactive LH levels are drastically suppressed. The effects on bioactive FSH levels, however, are not known. In this study, serum bioactive FSH was measured using an in vitro granulosa cell aromatase bioassay in four normal men given a LHRH agonist, [D-Trp6,Pro9-NEt]LHRH (LHRHA; 500 micrograms/day for 16 weeks), by sc infusion and testosterone enanthate (TE; 100 mg, im every 2 weeks) and in five men given 500 micrograms/day LHRHA by daily sc injection for 20 weeks and TE (100 mg every 2 weeks) from weeks 10 through 20. During the first study, serum immunoreactive FSH levels (IR-FSH) decreased by 56.5 +/- 4.8% (+/- SEM), and serum bioactive FSH (Bio-FSH) level decreased by 57.6 +/- 6.4%. The ratio of Bio-FSH to IR-FSH did not change. During the second study, both serum IR-FSH and Bio-FSH levels followed a triphasic pattern, decreasing slightly but not significantly immediately after initiation of LHRHA administration, progressively increasing to a peak (P less than 0.5 vs, baseline) at week 10, and then, after addition of TE to this regimen, decreasing slightly again. The Bio-FSH to IR-FSH ratio, as in the first study, did not change. When serum obtained at week 10 during the second study, just before initiation of TE, was chromatographed on a Sephadex G-100 column, IR-LH eluted in two distinct peaks, while IR-FSH eluted as a single peak. These results demonstrate that in normal men chronic LHRHA administration alone for up to 10 weeks or LHRHA plus TE for up to 16 weeks does not alter the qualitative characteristics of secreted FSH, since there was no dissociation between serum IR- and Bio-FSH levels.

Effect of altered thyroid hormone levels on hypothalamic-pituitary-adrenal function.

To determine whether alterations in serum thyroid hormone levels affect hypothalamic-pituitary-adrenal function, we measured the plasma immunoreactive (IR) ACTH and IR-cortisol responses to 1 microgram/kg BW ovine CRH (oCRH) given iv in the late afternoon and the plasma IR-ACTH, IR-cortisol, and IR-11-deoxycortisol responses to 2 g metyrapone given orally at midnight in 10 athyreotic patients during T4 treatment and 1 month after stopping T4 when they were biochemically, but not clinically, hypothyroid. Mean serum TSH increased from 0.7 +/- 0.9 (+/- SD) mU/L (normal range 0.5-4.9 mU/L) during T4 therapy to 107 +/- 82 mU/L after stopping T4. The serum total T4 level and free T4 index fell from 165 +/- 37 nmol/L and 1.9 +/- 0.4, respectively (normal range, 59-154 nmol/L and 0.9-2.5, respectively), to 19 +/- 9 and 0.2 +/- 0.1, respectively, after stopping T4. Basal plasma IR-ACTH and IR-cortisol levels at 0800 and 1630 h were similar during and after stopping T4 therapy. Peak plasma IR-ACTH and IR-cortisol levels after oCRH were significantly greater after stopping T4 (20 +/- 9.2 pmol/L and 880 +/- 260 nmol/L, respectively) than during T4 therapy (9.7 +/- 4.7 pmol/L and 720 +/- 190 nmol/L; P less than 0.01 and P less than 0.05, respectively). The mean integrated plasma IR-ACTH and IR-cortisol responses to oCRH were also significantly greater P less than 0.01 and P less than 0.05, respectively) after stopping T4 than during T4 therapy. Plasma IR-ACTH the morning after metyrapone was slightly (1.6-fold) but not significantly greater during therapy than after stopping T4 therapy (100 +/- 86 vs. 65 +/- 54 pmol/L, respectively). The plasma IR-11-deoxycortisol responses to metyrapone during and after stopping T4 therapy were similar (720 +/- 250 and 750 +/- 330 nmol/L, respectively), presumably because plasma IR-ACTH concentrations were maximally stimulating in both instances. These results indicate that thyroid hormone deficiency of short duration 1) increases corticotroph sensitivity to oCRH, 2) may diminish the plasma ACTH response to metyrapone-induced hypocortisolemia, and 3) has no apparent effect on the acute adrenal response to ACTH. These data together with those of previous studies that have shown reduced responses of the hypothalamic-pituitary-adrenal axis to metyrapone and hypoglycemia in hypothyroid patients suggest that the release of hypothalamic CRH and/or other ACTH secretagogues may be decreased in hypothyroidism.

Gonadotropins and testosterone escape from suppression during prolonged luteinizing hormone-releasing hormone antagonist administration in normal men.

The ability of prolonged administration of a LHRH antagonist, [Ac-delta 3Pro1,4F-D-Phe2,D-Trp3,6]LHRH (4F-antagonist), to suppress serum gonadotropin and testosterone levels was studied in normal men. The 4F-antagonist was given either as a continuous 13.3 micrograms/kg X h sc infusion for 72 h or as intermittent sc injections of 100 micrograms/kg every 6 h for 7 days. Serum FSH, LH, and testosterone levels decreased in the period immediately following initiation of 4F-antagonist administration. However, an escape toward baseline levels for each of these hormones occurred during prolonged antagonist administration. When men receiving the continuous infusion were challenged with iv bolus doses of 50 micrograms LHRH, the response of LH after the first 12 h of 4F-antagonist administration was similar to that before its administration. This gonadotropin and testosterone escape suggests that, at the doses used, the inhibitory action of the antagonist on gonadotropin secretion is progressively lost. The initial decrease in androgen levels could serve to augment endogenous LHRH release, which, in turn, overcomes the pituitary effects of the antagonist, or to augment endogenous LH secretion directly. These results demonstrate that the pituitary can escape from the suppressive effects of prolonged LHRH antagonist administration and partially restore serum gonadotropin and testosterone levels to normal in man.

Suppression of pituitary-gonadal function by a potent new luteinizing hormone-releasing hormone antagonist in normal men.

LHRH antagonists compete with endogenous LHRH for binding to receptors on pituitary gonadotrophs and thereby inhibit gonadal function by suppressing gonadotropin secretion. We studied the effects of a recently developed LHRH antagonist on the pituitary-gonadal axis in man. The antagonist Detirelix [( N-Ac-D-Nal(2)1, D-pCl-Phe2,D-Trp3, D-hArg(Et2)6, D-Ala10]LHRH) was given as a single sc injection to nine normal men at three dose levels (5, 10, and 20 mg) at intervals of at least 7 days. Serum FSH, LH, and testosterone levels were measured before treatment, at frequent intervals for 48 h, and 72, 96, and 168 h after administration of the antagonist. Mean serum FSH levels decreased (P less than 0.001) from 6.9 +/- 0.5 (+/- SEM) mIU/mL to nadirs of 4.4 +/- 1.1, 3.6 +/- 0.9, and 4.1 +/- 0.9 after the 5-, 10-, and 20-mg doses, respectively. Serum LH levels decreased (P less than 0.001) from 6.2 +/- 0.3 mIU/mL to nadirs of 3.3 +/- 0.4, 2.8 +/- 0.3, and 2.7 +/- 0.3 after all three doses. Serum testosterone levels decreased (P less than 0.001) in a dose-dependent fashion from 5.1 +/- 0.2 ng/mL to nadirs of 1.3 +/- 0.3, 0.9 +/- 0.3, and 0.6 +/- 0.1 after the same doses. After the initial testosterone decrease, however, escape occurred 12-28 h after the lower doses. The area under the response curve, describing hormone concentrations as a function of time during the study, diminished by 23 +/- 2%, 36 +/- 4%, and 36 +/- 3% for FSH, by 14 +/- 6%, 30% +/- 6%, and 34 +/- 5% for LH, and by 41 +/- 5%, 58 +/- 6%, and 68 +/- 4% for testosterone with the same doses, respectively. The apparent plasma disappearance half-life of Detirelix by RIA was at least 41 h after all three doses. Detirelix elicited only a minor local reaction; no systemic side-effects were observed within the dose range used. These results indicate that this LHRH antagonist is a safe, highly potent inhibitor of the human pituitary-gonadal axis with an exceptionally long duration of action.

Gonadotroph adenomas in men produce biologically active follicle-stimulating hormone.

Gonadotroph adenomas may exhibit qualitative and quantitative defects in gonadotropin biosynthesis and secretion. Hypersecretion of immunoreactive FSH dimers by these adenomas occurs frequently; however, it has not been known whether this FSH is biologically active. Using the granulosa cell aromatase bioassay and a highly specific immunoradiometric assay for FSH, we studied the serum bioactivity and bio- to immunoactivity (B/I) ratios of 14 men with FSH-secreting adenomas and compared these values to those of 11 age-matched normal men. In addition, three adenoma patients received TRH (400 micrograms, iv). The mean basal serum FSH level (international units per L), as measured by both bio- and immunoassays, and the FSH B/I ratios were significantly higher (P less than 0.02, by Kolmogorov-Smirnov test) in the adenoma patients than in normal men (mean +/- SEM; adenoma patients: bioactivity, 68.8 +/- 10.4; immunoreactivity, 34.8 +/- 13.7; B/I ratio, 3.4 +/- 0.6; normal men: bioactivity, 5.8 +/- 1.2; immunoreactivity, 6.4 +/- 0.8; B/I ratio, 0.90 +/- 0.1). Both bio- and immunoactive FSH rose after TRH injection, resulting in maintenance of the B/I (mean +/- SEM; pre-TRH: bio-FSH, 63.7 +/- 22.4; immuno-FSH, 28.0 +/- 14.1; B/I ratio, 2.8 +/- 1.2; post-TRH: bio-FSH, 125.6 +/- 42.7; immuno-FSH, 45.8 +/- 21.8; B/I ratio, 3.5 +/- 1.6). When gonadotroph adenoma cells from three separate patients were cultured and their conditioned media (n = 3) studied, relatively large amounts of both bio- and immuno-FSH were detected. Furthermore, the major isoelectric profile of bio-FSH (pH 4.9-3.0) in the conditioned medium from two such adenomas was shown by chromatofocusing to be comparable to that of purified human pituitary FSH (pH 5.2-3.6). We conclude that gonadotroph adenomas in men secrete FSH that is biologically active, both basally and in response to TRH.

Persistence of concordant luteinizing hormone (LH), testosterone, and alpha-subunit pulses after LH-releasing hormone antagonist administration in normal men.

LHRH antagonists suppress pituitary and gonadal function by competing with endogenous LHRH for binding to gonadotroph receptors. To determine the mechanism of suppression of gonadotropin secretion we studied the effects of a single dose of a LHRH antagonist on the pulsatile activity of serum bioactive LH (Bio-LH), immunoreactive LH (IR-LH), alpha-subunit, and testosterone for 24 h in normal men. The LHRH antagonist, Nal-Glu [( Ac-D2Nal1,D4ClPhe2,D3Pal3,Arg5,DGlu6-(AA), DAla10]LHRH) was given as a single sc injection of 5 mg to five normal men. Blood samples were collected every 10 min during a 10-h baseline period and for 14 h after administration of the antagonist. IR-LH, alpha-subunit, and testosterone were measured in triplicate, and Bio-LH in duplicate. Pulses were then evaluated using Cluster analysis; all replicates were entered in the pulse analysis. After administration of the Nal-Glu antagonist, IR-LH levels decreased (P less than 0.001) from 2.81 +/- 0.06 at baseline to a nadir of 0.75 +/- 0.02 U/L. Bio-LH levels followed the same pattern, decreasing by 89% (P less than 0.001) from 4.54 +/- 0.13 to a nadir of 0.51 +/- 0.13 U/L 6.8 h after the injection of Nal-Glu. In contrast, serum alpha-subunit levels did not change (P greater than 0.05) during the 14-h period after antagonist administration (0.85 +/- 0.01 and 0.75 +/- 0.01 microgram/L before and after Nal-Glu, respectively). Serum testosterone levels decreased by more than 80%, from 17.6 +/- 0.2 at baseline to a mean nadir of 3.3 +/- 0.7 nmol/L 12.8 h after Nal-Glu administration. Pulse frequency and the number of significant pulses remained the same for all of the measured hormones during the 10-h baseline period and the 14 h after Nal-Glu administration. In contrast, the pulse amplitude of IR-LH, Bio-LH, and testosterone decreased significantly after injection of the antagonist. The pulse amplitude of the alpha-subunit also declined, albeit not significantly. Coincidence analysis revealed that during both the 10-h baseline and the 14-h post-Nal-Glu period there was a highly significant (P less than 10(-5) nonrandom synchrony between peaks of IR-LH, Bio-LH, alpha-subunit, and testosterone. These results suggest that coordinate pulsatile secretion of IR-LH, Bio-LH, and testosterone persists after the administration of 5 mg Nal-Glu LHRH antagonist.(ABSTRACT TRUNCATED AT 400 WORDS)

Gonadotropin-releasing hormone-dependent chorionic gonadotropin secretion in a menopausal woman.

We report the evaluation of a 46-yr-old asymptomatic menopausal woman whose serum hCG concentrations remained persistently supra-normal for 3 yr (mean +/- SD, 20 +/- 10 IU/L; n = 19). Holo-hCG and beta-core fragments were detected in the patient's urine by Ultragel chromatography, followed by specific RIAs. Trophoblastic, germ cell, and other malignancies appeared to be excluded by the absence of serum tumor markers and imaging procedures of the pelvis, abdomen, breast, and chest. Administration of a single bolus dose of synthetic GnRH (100 micrograms) increased the serum hCG concentration by 50% (from 26 to 40 IU/L). Administration of the Nal-Glu GnRH antagonist (5 mg, sc, every 12 h for 1 week) decreased the serum hCG concentration from 27 to 4.6 IU/L. The pronounced decrease in the serum hCG concentration during antagonism of the action of endogenous GnRH by administration of Nal-Glu GnRH suggests that the pituitary is the source of the supra-normal serum hCG concentrations, because the pituitary is exposed to the highest concentration of endogenous GnRH.

Combined administration of a gonadotropin-releasing hormone antagonist and testosterone in men induces reversible azoospermia without loss of libido.

GnRH antagonists suppress pituitary and gonadal function by competing with endogenous GnRH for binding to receptors on pituitary gonadotrophs. We studied the effects of GnRH antagonist administration to men in a protocol simulating a likely male contraceptive regimen combined with a low dose of testosterone. The GnRH antagonist Nal-Glu was given daily (10 mg, sc) for 20 weeks to eight normal men, and a low dose of testosterone enanthate (25 mg, sc) was given every week. Sperm counts started declining during week 4, and complete azoospermia was reached within 6-12 weeks in six of the eight subjects. Subjects 7 and 8, whose sperm counts and serum gonadotropin levels were not suppressed after 10 weeks, were given 20 mg Nal-Glu starting at week 10. One became azoospermic at week 16, while the other's total sperm counts continued declining and reached a nadir of 1.4 million by week 20. Sperm motility and viability in this subject were completely suppressed after week 14. Sperm counts returned to baseline levels 12-14 weeks after the end of Nal-Glu administration. The mean serum LH level of the first six subjects decreased from 3 +/- 03. U/L at baseline to less than 0.1 U/L until week 20, and then levels returned to baseline. FSH levels similarly decreased from a combined mean of 3.6 +/- 0.9 U/L at baseline to below 0.3 U/L after 4 weeks of Nal-Glu administration. Serum mean testosterone levels between weekly injections of testosterone enanthate ranged from 27.4 +/- 5.9 to 4.8 +/- 1.4 nmol/L, but remained in the hypogonadal range (less than 10 nmol/L) for 4 of the 7 days. None of the subjects, however, complained of decreased libido or potency, as assessed by a questionnaire. No systemic or significant local side-effects were observed, other than a minimal reaction at the injection site. These data suggest that complete sustained azoospermia can be achieved in man, without loss of libido, by chronic administration of a GnRH antagonist plus testosterone.

Inhibition of follicle-stimulating hormone secretion from gonadotroph adenomas by repetitive administration of a gonadotropin-releasing hormone antagonist.

As a preliminary step in searching for a pharmacological treatment for gonadotroph adenomas, we administered the GnRH antagonist analog Nal-Glu GnRH to five patients, four men and a woman, with FSH-secreting gonadotroph adenomas in order to determine its effect on FSH secretion. Administration of a single 10-mg dose of Nal-Glu GnRH to four of the patients produced a significant decrease in the serum FSH concentration in two patients and returned the FSH level to normal in only one. Administration of 5 mg Nal-Glu every 12 h for 7 days, however, produced a significant (P less than 0.001) decrease, and to within the normal range, in four of the five patients (mean +/- SEM, 32.7 +/- 5.6 IU/L during the 3 days before treatment and 9.8 +/- 1.4 IU/L during the last 3 days of treatment). Also, in response to the 7-day treatment, LH fell significantly in all five patients, alpha-subunit fell in three, and testosterone fell in all four men. Administration for 6 weeks of the GnRH agonist analog leuprolide did not decrease the serum FSH concentration of one of the patients whose serum FSH did decrease in response to Nal-Glu GnRH. We conclude that repetitive administration of Nal-Glu GnRH may often inhibit FSH secretion by gonadotroph adenomas and that FSH secretion by gonadotroph adenomas may be dependent on endogenous GnRH secretion.

Effects on behavior of modulation of gonadal function in men with gonadotropin-releasing hormone antagonists.

The effects of acute gonadal suppression on sexual function and behavior were studied in eight normal men. Administration of a newly developed, potent gonadotropin-releasing hormone antagonist induced azoospermia and reduced levels of serum testosterone, luteinizing hormone, and follicle-stimulating hormone. These effects coincided with a reduction in outward-directed aggression in all men. Self-reported measures of anxiety and sexual desire revealed less consistent change over time. Measures of anger control, inward-directed anger, and affective state were unaffected.