Ovulation induced by synthetic luteinizing hormone-releasing hormone in the hamster.

A synthetic decapeptide, corresponding to the chemical structure of luteinizing hormone-releasing hormone from porcine hypothalami, was tested for the induction of ovulation in golden hamsters that had previously been treated with phenobarbital to prevent spontaneous ovulation. Subcutaneous injection of 0.089 to 0.357 nanomole of this synthetic luteinizing hormone-releasing hormone stimulated release of luteinizing hormone and induced ovulation.

Treatment of prostate cancer with gonadotropin-releasing hormone agonists.

It is now well established that chronic treatment with GnRH agonists offers an advantageous alternative to orchiectomy and estrogens for the treatment of prostate cancer. Castration levels of androgens can thus be easily achieved without side effects other than those related to castration levels of serum androgens. However, man is unique among species in having a high secretion rate of precursor adrenal steroids which are converted into active androgens in the normal prostate and prostatic cancer. All the enzymes required for the transformation of dehydroepiandrosterone sulfate, dehydroepiandrosterone, androstenedione, and androst-5-ene-3 beta, 17 beta-diol are present in prostatic tissue. Moreover, as shown in many systems, castration levels of serum testosterone (T) at 0.2-0.4 ng/ml exert significant androgenic activity in target tissues. In order to inhibit the action of androgens of both testicular and adrenal origin, GnRH agonists have been administered in association with the pure antiandrogen Flutamide in patients having clinical stage D2 (bone metastases) prostate cancer. A positive objective response assessed according to the criteria of the United States National Prostatic Cancer Project (USNPCP) has been observed in 84 of the 88 patients who had received no previous treatment (95.4%). After 2 yr of treatment, the probability of continuing response is 70% compared to 0-10% by previous approaches. In addition, the death rate at 2 yr is at 10.9% as compared to approximately 50% after standard hormonal therapy. When the same treatment was applied to patients who had received previous hormonal therapy (orchiectomy, estrogens or GnRH agonists alone) before showing a relapse, the response rate decreased to 62.9% and the death rate at 2 yr was 52%.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-response relationship of luteinizing hormone to luteinizing hormone--releasing hormone in man.

In previous clinical studies with highly purified porcine luteinizing hormone-releasing hormone (LH-RH), administration of the somewhat arbitrarily chosen doses of 700-1500 mug resulted in increased serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The present study determined the minimum effective dose as well as the relationship of the response of serum LH and FSH to the dose of LH-RH administered. Three normal men received i.v. injections of 1.1-810 mug of LH-RH. A dose of 10 mug of LH-RH caused a statistically significant elevation in serum LH. 30 mug of LH-RH significantly increased serum FSH levels. A highly significant linear trend was observed in the log dose-response curve. The results indicate that both LH and FSH release occurs in man with doses of LH-RH much lower than previously used and that a linear log dose-response relationship can be obtained.

Effects of decreasing the frequency of gonadotropin-releasing hormone stimulation on gonadotropin secretion in gonadotropin-releasing hormone-deficient men and perifused rat pituitary cells.

The effects of decreasing the frequency of pulsatile gonadotropin-releasing hormone (GnRH) stimulation on pituitary responsiveness were studied in (a) men with isolated GnRH deficiency who had achieved normal sex steroid levels during prior long-term pulsatile GnRH replacement and (b) perifused dispersed pituitary cells from male rats in the absence of sex steroids. In three groups of four GnRH-deficient men, the frequency of GnRH stimulation was decreased at weekly intervals from (a) every 2-3-4 h (group I), (b) every 2-8 h without testosterone replacement (group II), or (c) every 2-8 h with testosterone replacement (group III). In three groups of three columns of perifused dispersed pituitary cells, pulses of GnRH were administered every 2, 4, or 8 h. In groups I and II, mean area under the luteinizing hormone (LH) curve increased (P less than 0.025) and serum testosterone levels fell (P less than 0.035) as the frequency of GnRH stimulation was decreased. In group III, the area under the LH curve also increased (P less than 0.01) although serum testosterone levels were constant, thereby demonstrating that the increase in pituitary responsiveness to slow frequencies of GnRH stimulation occurs independently of changes in the sex steroid hormonal milieu. The area under the LH curve also increased in the perifused dispersed rat pituitary cells when the frequency of GnRH administration was decreased to every 8 h (P less than 0.05), thus demonstrating that the enhanced pituitary responsiveness to slow frequencies of GnRH stimulation is maintained even in the complete absence of gonadal steroids. Nadir LH levels fell in all three groups (P less than 0.01) as the frequency of GnRH stimulation was decreased. In contrast, mean peak LH levels, the rate of LH rise, and the rate of endogenous LH decay were constant as the frequency of GnRH stimulation was decreased. Finally, as the GnRH interpulse interval increased, mean LH levels fell, and mean follicle-stimulating hormone levels were stable or fell. These results indicate that (a) pituitary responsiveness to GnRH increases at slower frequencies of GnRH stimulation in models both in vivo and in vitro, (b) these changes in pituitary responsiveness occur independently of changes in gonadal steroid secretion, and (c) the increases in LH pulse amplitude and area under the curve at slow frequencies of GnRH stimulation are due to decreases in nadir, but not peak, LH levels. Slowing of the frequency of GnRH secretion may be an important independent variable in the control of pituitary gonadotropin secretion.

Selective inhibition of follicle-stimulating hormone secretion by estradiol. Mechanism for modulation of gonadotropin responses to low dose pulses of gonadotropin-releasing hormone.

Prepubertal girls and gonadotropin-releasing hormone (GnRH)-deficient females secrete follicle-stimulating hormone (FSH) preferentially in response to intravenous GnRH. With continued pulsatile GnRH stimulation, FSH secretion is reduced when plasma estradiol (E2) is increasing. To delineate the mechanisms involved in these changing gonadotropin responses, e studied the effect of low dose (0.025 micrograms/kg) pulsatile injections of GnRH in females with varying degrees and/or duration of endogenous GnRH deficiency (idiopathic panhypopituitarism, PHP; isolated growth hormone deficiency, IGHD; isolated gonadotropin deficiency, IGD; and anorexia nervosa, AN; both at low body weight and after weight regain). In patients presumed to have the most severe GnRH deficiency (PHP), responses of both FSH and luteinizing hormone (LH) were small and delayed, and no increase in plasma estradiol occurred during the 5 d of GnRH injections. In patients previously exposed to prepubertal or adult levels of endogenous GnRH secretion (IGHD, IGD, AN at low body weight), a rapid initial FSH response occurred that subsequently declined when plasma estradiol rose to concentrations greater than 40-50 pg/ml. Prior therapy with estrogen (micronized estradiol, Estrace) abolished FSH responses but LH responses were only slightly impaired. The degree of FSH response was dependent upon the time of initiation of estrogen relative to the onset of GnRH injections. Administration of estrogen after the first GnRH injection inhibited gonadotropin responses, whereas later estrogen therapy (after 1 d of GnRH pulses) blunted the GnRH induced FSH secretion without significantly impairing the LH response. In weight-regained anorexic patients who had spontaneous pulsatile LH secretion and a mean basal plasma estradiol concentration of 53 +/- 15 pg/ml, administration of GnRH pulses did not change plasma LH and a minimal FSH response was seen. The data indicate that the pattern of gonadotropin responses to low dose GnRH injections depends upon the degree of previous exposure of the pituitary to endogenous GnRH. Furthermore, estradiol selectively inhibits FSH secretion by a direct action on the pituitary gland. This action of estradiol provides an explanation for the selective reduction in FSH responses to GnRH seen during pubertal maturation in girls and during the mid-follicular stage of the menstrual cycle.

Long term superfusion of rat anterior pituitary cells: effects of repeated pulses of gonadotropin-releasing hormone at different doses, durations, and frequencies.

We investigated the temporal release of LH by rat pituitary cells superfused with repeated pulses of GnRH at different doses (amplitudes), frequencies, and pulse durations. Anterior pituitary (AP) cells prepared from ovariectomized rats were cultured on bio-beads and then placed in columns and superfused. The cells were stimulated intermittently for 24 h with synthetic GnRH given as pulses of 6-, 10-, or 15-min duration at frequencies of one pulse per 30, 60, or 90 min. In the first experiment we tested the temporal response of cells exposed to different doses of GnRH. At all doses, the first pulse of GnRH stimulated greater LH release than subsequent pulses. The response to subsequent pulses varied with dose. At low doses (1 and 5 X 10(-10)M) of GnRH, the AP cells stabilized and released similar amounts of LH in response to each sequential identical GnRH pulse for up to 24 h. In contrast, at high doses (10(-8) and 10(-6)M) of GnRH, the AP cells gradually released less LH with each pulse. During the initial pulses, the dose-response curves of LH release were linear between doses of 5 X 10(-10) to 1 X 10(-6) M GnRH. Thereafter, the maximum response was diminished, and the slope of the dose-response curve was reduced. In subsequent experiments we found that the decline in responsiveness with time was not due to either degradation of GnRH in the medium or loss of cell viability. The low responsiveness to high GnRH pulses at the end of the superfusion period could be overcome temporarily by further increasing the dose of GnRH. In the presence of high doses, changing GnRH pulse frequency from one 6-min pulse per h to one 6-min pulse per 1.5 h or changing duration from one repeated 10-min pulse per h to one repeated 6-min pulse per h had no detectable effect on the temporal pattern of LH release. These results suggest that, similar to constant infusion, pulsatile delivery of GnRH at high doses to AP cells can induce cell refractoriness to GnRH. This loss of responsiveness probably involves factors in addition to depletion of GnRH receptors and the releasable LH pool. In contrast, pulsatile delivery of low doses of GnRH appears to maintain LH release at a relatively constant level for up to 24 h.

Pharmacokinetics of gonadotropin-releasing hormone: comparison of subcutaneous and intravenous routes.

Pulsatile administration of GnRH has been used to stimulate gonadal function in both hypogonadotropic men and women; however, deficient responses were observed with the sc in contrast to the iv route of hormone delivery. To clarify whether this was due to altered bioavailability, we compared the pharmacokinetics of these two routes of GnRH administration by bolus injection and steady state continuous infusion methods. Synthetic GnRH was administered by both sc and iv routes to 14 hypogonadotropic patients (11 women and 3 men) as a bolus (5 micrograms in 25, 100, or 250 microliters, sc, and 250 microliters, iv; n = 6) or by continuous iv or sc infusion (3.17 micrograms/h for 6 h; n = 11). In single dose studies, plasma immunoreactive GnRH (IR-GnRH) peaks were earlier and higher (400 vs. 93.5 pg/ml) and returned to baseline sooner (less than 60 vs. greater than 120 min) after iv than after sc bolus injection. Plasma IR-GnRH levels were lower between 1 and 5 min, but higher between 30-90 min after sc injection compared with iv bolus injection. During the continuous infusions, plateau levels of IR-GnRH between 2 and 6 h were 34% lower with sc delivery (67.5 vs. 102.4 pg/ml), indicating irreversible losses of about one third of GnRH injected sc. In patients undergoing pulsatile GnRH therapy delivered by programmed portable minipumps, plasma IR-GnRH profiles were highly damped after sc administration, but retained an intermittent pulse wave form with the iv route. These data suggest that pharmacokinetic differences in the sc and iv routes of GnRH administration are due to a combination of prolonged and delayed absorption with reduced bioavailability of GnRH via the sc route. The consequent damping of the plasma GnRH profiles with sc administration may contribute to differences in the clinical efficacy of pulsatile GnRH regimens, and specific modifications of pulsatile regimens may be required to adapt the physiological requirements of an intermittent plasma GnRH wave form to the damped and reduced bioavailability of sc GnRH therapy.

Subcutaneous administration of gonadotropin-releasing hormone: absorption kinetics and gonadotropin responses.

To evaluate the suitability of the sc route for the pulsatile delivery of GnRH, plasma GnRH, LH, and FSH levels were measured by RIA in five women with hypothalamic amenorrhea after sc injection of single doses of 2.5, 5, and 10 micrograms GnRH. The results were compared with those obtained after bolus iv injection of 10 micrograms GnRH. After sc injection, plasma GnRH levels rose to a dose-related maximum after 5-10 min and fell to less than 10% of the peak value by 90 min. The mean plasma disappearance half-time was 24 min (range, 18-30 min). After bolus iv injection, an initial rapid phase of disappearance (t1/2, 2.8 min) was followed by a slower phase (t1/2, 33 min), falling within the 95% confidence intervals for the disappearance half-time after sc administration (12-36 min). The patterns of LH response to sc and iv GnRH were similar, with maximum levels reached between 20 and 30 min after injection, then declining to 50-69% of the peak value by 90 min after sc injection and 61% of the peak value 90 min after iv injection. There was no significant difference between peak LH responses to 10 micrograms iv and sc doses of GnRH [15.2 +/- 2.5 (+/- SEM) vs. 13.2 +/- 2.2 IU/L]. Subcutaneous administration of three consecutive GnRH pulses at 90-min intervals to four women resulted in gonadotropin responses to each GnRH pulse. We conclude that sc GnRH administration results in pulsatile plasma GnRH and gonadotropin responses, the latter resembling those seen after iv GnRH. These results confirm the suitability of the sc route for pulsatile GnRH delivery.

Effects of increasing the frequency of low doses of gonadotropin-releasing hormone (GnRH) on gonadotropin secretion in GnRH-deficient men.

The effects of increasing the frequency of pulsatile GnRH administration on LH and FSH responsiveness were studied in five GnRH-deficient men who had achieved normal sex steroid levels during prior long term GnRH replacement. Intravenous doses of GnRH were employed that had previously been demonstrated to produce LH and FSH levels in each subject similar to those in normal men. Both acute and chronic changes in pituitary responses were studied after progressive increases in GnRH frequency (from every 120 to 60 min, from 60 to 30 min, and from 30 to 15 min) during three 12-h admissions, each separated by 7 days. During the two intervals between the studies GnRH frequency was 60 and 30 min, respectively. Pituitary responses were characterized by determining the mean serum LH and FSH levels, LH pulse amplitudes, and mean LH and FSH levels which were normalized for the frequency of GnRH administration (nLH and nFSH). As the frequency of GnRH stimulation was increased acutely, mean serum LH levels rose progressively, in contrast to both LH pulse amplitude and nLH levels which decreased, while serum testosterone (T) concentrations remained constant. No further evidence of gonadotroph desensitization occurred after chronic GnRH administration at either 60- or 30-min intervals. At higher frequencies of GnRH stimulation, discrete pulses of LH were not always apparent after injections of GnRH, and in two men, marked destabilization of the gonadotroph responses occurred. Even without detectable LH pulses, serum T levels did not decline during administration of GnRH at intervals as rapid as 15 min. In contrast, there was no change in mean FSH concentrations, although nFSH values decreased progressively as the GnRH frequency was increased. nFSH levels fell to a greater degree than nLH after each increase in GnRH frequency. Thus, pituitary gonadotroph responsiveness to a fixed dose of GnRH decreased as the frequency of GnRH stimulation increased. FSH responsiveness decreased to a greater degree than did LH. Gonadotropin secretory responses are destabilized at higher frequencies of GnRH administration. Pulsatile LH stimulation of the testes does not appear necessary to maintain T secretion.

Hypogonadotropic hypogonadism: hormonal responses to low dose pulsatile administration of gonadotropin-releasing hormone.

Patients with isolated gonadotropin deficiency were studied to determine whether pulsatile low dose gonadotropin-releasing hormone (GnRH) could induce the hormonal changes seen during normal puberty. Four male and two female patients with immature responses to a standard GnRH test (2.5 micrograms/kg) were given GnRH (0.025 micrograms/kg) iv every 2 h for 5 days. FSH responses varied between the sexes, and FSH concentrations in males rose continuously to 17.2 +/- 4.7 mIU/ml on day 5. In the females, FSH peaked at 13.8 and 15.8 mIU/ml on days 3-4 and then declined. The males showed increasing and the females decreasing incremental FSH responses to GnRH. LH concentrations and incremental responses to GnRH rose throughout the study in both sexes. Plasma testosterone rose slightly in the males to 0.7 +/- 0.2 ng/ml (P < 0.05), but in females estradiol increased to follicular range concentrations of 128 and 102 pg/ml. Standard GnRh tests on day 6 revealed maturation of gonadotropin responses in all patients. After termination of pulsatile GnRH, four patients were given single low dose GnRH injections on two to seven occasions over a period of 2-32 days. Initial LH responses were 2- to 14-fold greater than those seen on day 5 of pulsatile GnRH, and decreased over the next 3 weeks. FSH responses showed less initial augmentation and declined more slowly. Low dose pulsatile administration of GnRH to patients with isolated gonadotropin deficiency results in changing patterns of hormone secretion similar to those seen during puberty. Exaggerated pituitary sensitivity to GnRH may be present long after a brief period of GnRH stimulation, and may indicate previous rather than current secretion of GnRH.

Pharmacodynamics of gonadotropin-releasing hormone (GnRH). II. Pattern of GnRH delivery alters pituitary luteinizing hormone secretion in women.

The pulse frequency, amplitude, and mode of administration of GnRH all influence gonadotropin secretion and, ultimately, pituitary-gonadal function. We studied plasma LH responses to repetitive iv administration of GnRH given hourly for 5 h as a 2-microgram rapid (less than 15 s) bolus dose or a 2-microgram dose infused for 15 min of each hour in seven women deficient in endogenous GnRH and sex steroids. Plasma LH levels, measured at 10-min intervals throughout the 5-h period, rose more briskly (pattern X time course interactions: F = 3.33; P less than 0.0001) to higher levels overall (F = 11.7; P = 0.014) after rapid bolus GnRH administration than after GnRH infusion. Plasma FSH levels increased during both modes of delivery, with higher responses to rapid bolus GnRH administration (P = 0.005). Plasma estradiol levels did not change during either 5-h study. We conclude that the pattern of delivery of GnRH is a determinant of pituitary LH and FSH secretion in untreated hypogonadotropic women, and therefore, that alterations in the GnRH wave form and/or peak plasma GnRH concentrations consequent upon different rates of GnRH entry into the blood-stream may explain the different responses that occur when GnRH is given by different routes.

Stimulation of spermatogenesis and biological paternity by intranasal (low dose) gonadotropin-releasing hormone (GnRH) in a male with Kallmann's syndrome: intraindividual comparison of GnRH and gonadotropins for stimulation of spermatogenesis.

Intranasal (in) GnRH spray caused induction and maintenance of spermatogenesis and biological paternity in a 28-yr-old man with Kallmann's syndrome. Prior treatment had included GnRH analog administration, which failed to induce puberty, and testosterone (T) enanthate weekly. Prior hCG/human menopausal gonadotropin therapy had resulted in high normal serum T levels and near-normal semen quality, but during subsequent hCG therapy, spermatogenesis markedly decreased. The patient had then received 250 mg T enanthate/month for 2 yr and 7 months; it was discontinued 7 weeks before the in GnRH study began. At its start (July 1984) the subject's testis size was 7 mL, and he had azoospermia, low serum LH and FSH levels, and a serum T of 74 ng/dL (2.6 nmol/L). GnRH was administered in a dose of 200 micrograms (20-120 ng/kg were absorbed into the circulation) every 2 h, seven to nine times a day, between 0700 and 2400 h for 242 days. After 12 days of treatment, serum T had increased to 519 ng/dL (18.0 nmol/L). After 70 days, the patient's sperm count was 11.5 million/mL (4.5 mL ejaculate volume; 70% motility; 36% normal morphology); on day 185, sperm count was 31 million/mL (4 mL ejaculate volume; 54% motility; 36% normal morphology). His spouse conceived on day 162 and delivered a fullterm daughter 265 days later. The probability of paternity was 99.9994%. Our results suggest that induction and maintenance of spermatogenesis as well as fertility in hypothalamic hypogonadism can be achieved with in GnRH therapy if pituitary and testicular function are intact. Spermatogenesis induced by in GnRH has the same quality as spermatogenesis induced by hCG/human menopausal gonadotropin therapy. Patient compliance is probably the most important factor for the success of in GnRH therapy.

Gonadotropin release by clinically nonfunctioning and gonadotroph pituitary adenomas in vivo and in vitro: relation to sex and effects of thyrotropin-releasing hormone, gonadotropin-releasing hormone, and bromocriptine.

We studied in vivo hormone levels and in vitro hormone and subunit release in a group of 22 patients who were operated upon because of a clinically nonfunctioning or gonadotroph pituitary adenoma. In vivo, 5 of the 22 patients, all men, had hypersecretion of FSH, LH beta, or alpha-subunit. An elevated ratio of serum alpha-subunit to LH and FSH was found in 6 of 8 women in vivo, although in all 6 women serum LH, FSH, and alpha-subunit levels were low. LH, FSH, alpha-subunit, LH beta, or a combination of these glycoprotein hormones could be demonstrated in 19 of 22 cultured adenomas. We conclude that 1) virtually all clinically nonfunctioning adenomas contain or release gonadotropins or their subunits in vitro; 2) in vivo hypersecretion of these hormones and subunits occurs infrequently, and in this series only in men; 3) an elevated ratio of alpha-subunit to LH and FSH is frequently found in women and may prove to be a useful diagnostic tool; 4) responses to TRH and bromocriptine do not depend on baseline gonadotropin levels, either in vitro or in vivo, implying that the distinction between gonadotroph adenomas and adenomas without hypersecretion of gonadotropins in vivo is absent where hormone dynamics are concerned.

Recovery of hormone secretion after chronic gonadotropin-releasing hormone agonist administration in women with polycystic ovarian disease.

Persistent suppression of gonadotropin and ovarian steroid production can be achieved in women with polycystic ovarian disease (PCO) by daily administration of a long-acting GnRH agonist (GnRHa). This study was designed to determine the patterns of recovery of clinical responses and hormonal secretion after chronic GnRHa administration in women with PCO. Six women with PCO were treated with daily sc injections of [D-His6(imBzl),Pro9-NEt]GnRHa (100 micrograms) for 6 months. Blood samples were obtained at the time of and three times weakly for 90 days after discontinuation of agonist therapy. In five women who did not ovulate, the suppressed serum FSH levels rose to pretreatment values within 10 days. In contrast, a gradual and progressive increase in serum LH (as measured by bioassay and immunoassay) was apparent by day 18. The LH increase coincided with progressive increases in serum estrone (E1), androstenedione, and testosterone. Serum estradiol (E2) began to rise on day 28. All hormones returned to their pretreatment baseline values within the 90-day recovery interval, with the exception of E2. Trend analysis of the slopes of recovery revealed that the incremental secretion patterns of E1, E2, androstenedione, and testosterone differed significantly from that of FSH, but not from those of bioactive or immunoactive LH. Serum progesterone, dehydroepiandrosterone sulfate, and cortisol did not change after withdrawal of GnRHa. One woman ovulated spontaneously on day 52 before which her hormone secretion patterns were indistinguishable from those of the other women. In summary, 1) during recovery after discontinuation of chronic GnRH agonist therapy the patterns of FSH and LH release suggested resumption of endogenous GnRH action on the pituitary with greater release of FSH than LH, a pattern that would be expected in the absence of ovarian steroid influence; 2) the lack of early estrogen production despite the increase in serum FSH concentrations suggests inadequate FSH secretion, abnormal ovarian responsiveness to FSH, or impaired FSH bioactivity; 3) androgen secretion was provoked by the increase in LH secretion; 4) per unit LH measured by bioassay, greater ovarian androgen secretion was stimulated in PCO than ovulatory women; and 5) the likelihood of spontaneous ovulation during recovery was minimal.

Pituitary stimulation by combined administration of four hypothalamic releasing hormones in normal men and patients.

Ten normal young men (22-28 yr of age), within 10% of their ideal body weight, were given the four releasing hormones (TRH, 200 micrograms; GnRH, 100 micrograms; ovine corticotropin-releasing hormone, 50 micrograms; GH-releasing hormone, 80 micrograms) iv on separate days and then in combination on the same day. Plasma TSH, PRL, FSH, LH, cortisol, ACTH, and GH were measured by RIA in samples collected from 20 min before to 120 min after injection. There were no significant differences in responses to the separate and combined tests for FSH, LH, cortisol, ACTH, and GH. The plasma TSH (0.001 less than P less than 0.01) and PRL (P less than 0.001) responses were significantly higher after the combined test. The tolerance was identical to that of TRH alone. In eight patients studied after pituitary surgery, combined administration provided results comparable to those obtained after separate administration of TRH, GnRH, and insulin.

Hypogonadotropic secondary amenorrhea in diabetes: effects of central opiate blockade and improved metabolic control.

The effect of improving diabetic control on secondary hypogonadotropic amenorrhea was investigated in patients with insulin-dependent diabetes mellitus (IDDM). Second, the hypothesis that increased central (hypothalamic) opiate inhibition may have been responsible for the suppression of gonadotropin-releasing hormone (GnRH) was tested by observing the effect of a four-hour naloxone infusion (1.4 mg/hour) on serum gonadotropin levels. All known causes of secondary amenorrhea were excluded before patients were eligible for the study. The median duration of amenorrhea was six years, and median body weight was 101 percent of ideal. After six months of improved metabolic control (n = 5) using intensified conventional therapy or continuous subcutaneous insulin infusion, the level of glycosylated hemoglobin dropped from 11.8 +/- 0.9 percent to 8.5 +/- 0.5 percent (p less than 0.005), and body weight increased from 60.5 +/- 1.8 kg to 64.7 +/- 1.4 kg (p less than 0.02). Menses did not, however, return in any patient. There was no significant change in serum levels of estradiol, progesterone, dihydroxyepiandrosterone, testosterone, prolactin, basal or GnRH-stimulated luteinizing hormone, or follicle-stimulating hormone. There was no change in the levels of luteinizing hormone or follicle-stimulating hormone during the naloxone infusion either during poor metabolic control or after six months of improved metabolic control. In conclusion, a form of secondary hypogonadotropic amenorrhea was identified in patients with IDDM that did not remit with sustained improvements in metabolic control. It did not appear to be mediated through increased central opiate tone.

The significance of small pulses of gonadotrophin-releasing hormone.

A series of experiments was conducted to ascertain the significance of 'small' pulses of gonadotrophin-releasing hormone (GnRH). In the first experiment, ovariectomized hypothalamo-pituitary disconnected (HPD) ewes were given 250 ng pulses of GnRH every 2 h for 1 week, 25 ng pulses every 2 h for 24 h, 25 ng pulses hourly for 24 h and then alternating hourly pulses of 25 and 250 ng. During the 25 ng pulses, LH was not detectable in plasma and FSH concentrations declined after 2 days. Following the 25 ng pulses, the resumption of 250 ng pulses led to exaggerated LH responses (mean +/- S.E.M. pulse amplitude 18.7 +/- 1.7 vs 10.2 +/- 1.2 micrograms/l in the first week). In a second experiment, ovariectomized-HPD ewes were maintained on 250 ng GnRH pulses every 2 h for 1 week and were then given three 25 ng pulses mid-way between the 250 ng pulses. Samples of blood were taken over three 250 ng pulses without 25 ng insertions and over three pulses with insertions. The insertion of 25 ng GnRH pulses did not cause LH pulses in their own right and did not alter the LH responses to the 250 ng pulses. In a third experiment, 50 ng GnRH pulses were inserted between the 250 ng GnRH pulses, as in experiment 2; these 50 ng pulses caused small LH pulses and led to a reduction in the response of the LH pulse amplitude to the 250 ng pulses. The 'small' LH pulses which occurred in response to 50 ng GnRH compensated for the reduced responses to the 250 ng pulses.(ABSTRACT TRUNCATED AT 250 WORDS)

An improved computational method to assess pituitary responsiveness to secretagogue stimuli.

OBJECTIVE: The quantitative assessment of gland responsiveness to exogenous stimuli is typically carried out using the peak value of the hormone concentrations in plasma, the area under its curve (AUC), or through deconvolution analysis. However, none of these methods is satisfactory, due to either sensitivity to measurement errors or various sources of bias. The objective was to introduce and validate an easy-to-compute responsiveness index, robust in the face of measurement errors and interindividual variability of kinetics parameters. DESIGN: The new method has been tested on responsiveness tests for the six pituitary hormones (using GH-releasing hormone, thyrotrophin-releasing hormone, gonadotrophin-releasing hormone and corticotrophin-releasing hormone as secretagogues), for a total of 174 tests. Hormone concentrations were assayed in six to eight samples between -30 min and 120 min from the stimulus. METHODS: An easy-to-compute direct formula has been worked out to assess the 'stimulated AUC', that is the part of the AUC of the response curve depending on the stimulus, as opposed to pre- and post-stimulus spontaneous secretion. The weights of the formula have been reported for the six pituitary hormones and some popular sampling protocols. RESULTS AND CONCLUSIONS: The new index is less sensitive to measurement error than the peak value. Moreover, it provides results that cannot be obtained from a simple scaling of either the peak value or the standard AUC. Future studies are needed to show whether the reduced sensitivity to measurement error and the proportionality to the amount of released hormone render the stimulated AUC indeed a valid alternative to the peak value for the diagnosis of the different pathophysiological states, such as, for instance, GH deficits.

Closed intravenous administration of gonadotropin-releasing hormone: safety of extended peripheral intravenous catheterization.

The use of pulsatile gonadotropin-releasing hormone is an effective means of inducing ovulation, but requires prolonged intravenous (IV) or subcutaneous administration. We hypothesized that the use of self-contained infusion pumps using fluids maintained in a closed system would permit safe peripheral IV administration of gonadotropin-releasing hormone, and possibly other hormones, over prolonged intervals. Thirty-eight female patients undergoing pulsatile IV gonadotropin-releasing hormone therapy were followed for 1958 catheter days (230 catheters). Catheters were removed for signs of local inflammation, at the completion of a treatment episode or, initially, at routine intervals of 7-10 days. There were no episodes of fever (temperature over 37.5C) and three episodes of local inflammation. The incidence of significant catheter-tip cultures was 11%, and none were associated with local inflammation. There were four positive blood cultures (2%), none associated with local or systemic signs of infection. We conclude that the use of a closed system of prolonged peripheral IV cannulation is relatively safe when combined with fastidious care of the catheter site and careful outpatient monitoring for long-term administration of pulsatile gonadotropin-releasing hormone.

Plasma gonadotropin-releasing hormone profiles after intravenous and subcutaneous bolus injection in thin and obese women.

Other studies of plasma gonadotropin-releasing hormone profiles after bolus injection have revealed earlier, sharper peaks and higher blood gonadotropin-releasing hormone levels with the intravenous (IV) than with the subcutaneous route of administration. We used both routes to administer gonadotropin-releasing hormone by bolus injection to thin and obese subjects. Plasma gonadotropin-releasing hormone profiles after IV administration were similar in both groups. The subcutaneous route produced flatter, delayed, and lower peaks, an effect markedly exaggerated in obese subjects, who demonstrated 95% lower peak gonadotropin-releasing hormone levels compared with the IV route and 64% lower levels than thin subjects after subcutaneous administration. These findings may be relevant to therapeutic failures observed in obese subjects using the subcutaneous route.