Mating and pregnancy can occur in genetically hypogonadal mice with preoptic area brain grafts.

Adult female hypogonadal mice, in whom hypogonadism is secondary to a genetic deficiency in hypothalamic gonadotropin-releasing hormone (GnRH), are infertile. Mating, pregnancy, and delivery of healthy litters were achieved after transplantation of normal fetal preoptic area tissue, a major site of GnRH-containing cell bodies, into the third ventricle of adult female hypogonadal mice. Immunocytochemistry revealed GnRH-containing neurons in the grafts and GnRH-containing processes extending to the lateral median eminence of the host brains.

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.

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.

The nature of the gonadotropin-releasing hormone stimulus-luteinizing hormone secretory response of human gonadotrophs in vivo.

To examine the stimulus-secretion response of human pituitary gonadotrophs in vivo, we applied a new multiple parameter deconvolution technique to analyze (1) exogenous GnRH-stimulated LH secretory responses in 10 men with isolated hypogonadotropic hypogonadism (IHH), and (2) endogenous and exogenous GnRH-stimulated LH secretory responses in 8 normal men. The GnRH-deficient men were given 4 bolus doses of synthetic GnRH (7.5, 25, 75, and 250 ng/kg) iv at 2-h intervals in randomized order after long term pulsatile GnRH administration. The normal men were studied by sampling blood at 10-min intervals for 12 h basally and after 2 consecutive 10-micrograms iv GnRH doses. The serum LH peaks in both groups were subjected to quantitative deconvolution to resolve underlying LH secretory and clearance rates simultaneously. Such analyses revealed that exogenous GnRH-induced LH secretory episodes in GnRH-deficient men with IHH could be modeled as algebraically Gaussian distributions of instantaneous LH secretory rates with a mean half-duration of 14 +/- 2 min. The simultaneously resolved half-life of endogenous LH disappearance was 71 +/- 5 min. The log dose-response relationship for GnRH dose vs. maximal LH secretory rate or vs. calculated mass of LH released per secretory burst was linear. In contrast, varying GnRH doses did not alter the duration of LH secretory bursts, the half-time of LH disappearance, or the latency of LH secretory bursts after iv GnRH injections (viz. 7.6 min). Deconvolution analysis of the spontaneous (endogenous GnRH-stimulated) LH peaks in normal men revealed a mean half-duration of secretory bursts of 9.9 +/- 1.5 min, and a mean half-time of endogenous LH disappearance of 76 +/- 5 min. These values were not significantly different from those in the GnRH-treated normal or GnRH-deficient men. In summary, deconvolution analysis of LH release in men with IHH revealed a significant linear relationship between iv doses of pulsed GnRH and computer-resolved LH secretory rate and/or the mass of LH released per secretory event. In contrast, varying doses of GnRH did not alter the lag time between the GnRH stimulus and the LH secretory burst, the duration of LH secretion, or the calculated half-life of the LH released. We conclude that GnRH exerts dose-dependent effects on specific attributes of the secretory response of human gonadotrophs in vivo.

Homologous ligand induction of pituitary gonadotrophin-releasing hormone receptors in vivo is protein synthesis dependent.

This study demonstrates that a single subcutaneous injection of gonadotrophin-releasing hormone (GnRH) (60 ng) to GnRH-deficient (hpg) male mice causes a doubling of pituitary GnRH receptors (GnRH-R). No change in GnRH-R occurs during the time of LH release (15-60 min) or up until 4 h post-GnRH. Between 4 and 12 h there is a progressive increase in GnRH-R, which is still apparent 24 h later. No induction of GnRH-R occurs after the same treatment of intact adult normal mice. The same degree of GnRH-R induction occurs 12 h after a single GnRH injection (60 ng) to orchidectomized hpg male mice, indicating that this effect is mediated by a direct action of GnRH on the pituitary gonadotroph, rather than being secondary to stimulation of some gonadal product. Homologous ligand GnRH-R induction in hpg mouse pituitaries in vivo is prevented by prior treatment with cycloheximide, a non-specific protein synthesis inhibitor. Cycloheximide alone had no effect on GnRH-R in normal male mice but when combined with GnRH caused a 40% depletion of receptors, implying ligand-induced receptor loss without subsequent replenishment. The similarity between the extent, time-course, and dependence on protein synthesis of GnRH induction of its own receptors in vivo and in cultured pituitary cells in vitro indicates that the hpg mouse pituitary behaves like an in vivo pituitary cell culture system in this respect. Similarity of data derived from this in vivo model provides direct support for the view that in vitro studies on the cellular mechanism of GnRH action can be physiologically relevant to the intact animal.

Male transmission of the gene for isolated gonadotropin-releasing hormone deficiency.

Three black women, daughters of the same father but three unrelated mothers, presented with isolated gonadotropin deficiency (IGD). Clinically, the patients had no midline defects and intact smell and taste senses. Biochemically, the essential feature was very low unstimulated and stimulated follicle-stimulating hormone and luteinizing hormone levels, even after priming with gonadotropin-releasing hormone over a 5-day period. Growth hormone response to insulin-induced hypoglycemia was somewhat blunted, but prolactin, cortisol, and thyroid-stimulating hormone responses were quite normal. All three patients had the 46,XX karyotype; clinical or biochemical aberrations could not be demonstrated in any of the remaining family members. The disorder was, apparently, transmitted by the deceased father, who manifestly did not have an IGD deficiency nor any of the midline stigmata associated with IGD. The mode of inheritance seems most likely to be autosomal dominant with variable penetrance.

Endocrinological basis of hot flushes.

Hot flushes are frequent among women during natural, surgical, or pharmacological menopause. The available data suggest the involvement of estrogens, progestins, catecholestrogens, catecholamines, dopamine, endorphins, prostaglandins, luteinizing hormone (LH) and luteinizing hormone-releasing hormone (LH-RH) in the pathogenesis of flushes. At present the estrogen withdrawal and pulsatile luteinizing hormone (LH) secretion theories are most commonly accepted for explaining the development of this symptom. The use of LH-RH agonists offers an opportunity to focus on the probable origin and region that regulate the events of this phenomena, since the administration of this drug is associated with hot flushes, in spite of low gonadotropins and normal estrogen levels. Current data may suggest that the origin of this neurovegetative symptom lies in the hypothalamus.

Pubertal aberrancy. Etiology and clinical approach.

A study of 252 patients with pubertal aberrancy was done at the Medical College of Georgia. Patients were classified into hypogonadal and eugonadal categories. Ovarian failure is the most common cause of delayed sexual development. Congenital absence of the uterus and vagina and physiologic delay of puberty follow as frequently diagnosed etiologies. Pubertal aberrancy is no longer considered a benign entity since it is associated with morbidity, mortality and significant compromise of reproductive potential. The physical, emotional and social well-being of these patients is dependent upon expedient evaluation and treatment and on appropriate education and counseling.

Adolescent menstrual irregularity.

Amenorrhea and oligomenorrhea in the adolescent female are often the result of anovulation due to an immature hypothalamic-pituitary-ovarian axis. A careful history, physical examination and selected laboratory tests can help to differentiate this type of transient menstrual irregularity from the large number of endocrine and anatomic abnormalities that also present in this age group.

PIP: The workup of the adolescent with menstrual dysfunction is directed toward separating the "functional" irregular menstrual pattern of an immature hypothalamic/pituitary/ovarian (HPO) axis from the large number of endocrine and anatomic abnormalities that can become manifest in this age group. The HPO axis is not fully mature at menarch. Since the positive feedback response to estrogen, which allows ovulation, is frequently absent in the immediate postmenarchial peroid, menstrual irregularity is common. 55% of cycles are anovulatory in the 1st year. With futher maturation of the HPO axis a pattern of regular ovulatory cycles emerges, and in women 11 years after menarche by age 18 but a basic evaluation is indicated if menarche does not occur by age 16 or if secondary sexual development does not being by age 14. Secondary amenorrhea is the absence of menses for at least 3 months in a patient who previously had established cycles. With the exception of anatomic abnormalities of the lower reproductive tract that result in primary amenorrhea exclusively, there is considerable overlap between the differential diagnosis of primary and secondary amenorrhea. Causes of amenorrhea in adolescents are pregnancy, drugs and systemic diseases, hypothalamic and pituitary amenorrhea, "postpill" amenorrhea; hyperprolactinemia, androgen resistance, congenital anomalies of the genital tract, and androgen excess. Despite the large number of disorders that can cause menstrual abnormalities, the initial workup of the patient who presents with amenorrhea or delayed development can be simplified to a careful history, physical examination, and a few screening laboratory tests. The adolescent who has no development by age 14 or no menarche by age 16, whose menses cease for 4 months or more, or who has persistent oligomenorrhea or signs of androgen excess deserves an evaluation. Since the option of 1st trimester therapeutic abortion depends on early diagnosis of unwanted pregnancy, this diagnosis should be excluded without delay. The history should include: neonatal history -- maternal ingestion of virilizing hormones, previous maternal miscarriages, congenital lymphedema; family history -- heights of family members, age at menarche and fertility of female family members, and history of endocrine disorders; growth and pubertal developments; past medical history -- chronic disease, congenital anomalies, previous surgery, radiation exposure, chemotherapy, or drug use; and review of symptoms. The physical examination should include: height, weight, arm span, blood pressure; assessment of sexual maturity; and endocrine and gynecologic assessment. The screening tests for the patient with amenorrhea include urinary HCG, complete blood count, sedimentation rate, thyroid function, prolactin, FSH and LH, and assessment of estrogen status.

[Treatment of functional infertility, caused by luteal deficiency, with pulsatile perfusion of gonadotropin releasing hormone]. / Luteális elégtelenségen alapuló funkcionális meddöség kezelése gonadotropin releasing hormon pulzációs adagolásával.

The prehistory of cyclical development of corpus luteum goes back to early follicular phase. Reduced secretion or defective rhythm of gonadotropin releasing hormone (GnRH) can later cause unperfect ovulation or corpus luteum insufficiency. The authors carried out a low-dose pulsatory GnRH-treatment on eight patients with luteal insufficiency, who were earlier treated unsuccessfully with other ovulation-inductive methods (clomiphene, hCG, bromocryptin). As a result of GnRH administration hypertherm period expanded, plasma progesteron level increased and three pregnancies occurred. In their opinion exogenic administration of GnRH results in an improvement of luteal function.

Repair of reproductive deficits by neural transplantation.

Transplantation of brain tissue has been used to ameliorate the genetic lesion of the hypogonadal mutant mouse. This animal does not synthesize gonadotropin-releasing hormone (GnRH) and so has an infantile reproductive system. Implantation of normal fetal or neonatal preoptic area containing GnRH neurons reverses many aspects of the reproductive deficiency. Pituitary and plasma levels of gonadotropins rise, followed by growth of the gonads and sexual organs. Pituitary release of gonadotropins is episodic, suggesting that the grafted tissue is integrated into the "pulse generator." The vast majority of grafted animals do not show castration-induced elevations of luteinizing hormone (LH) nor respond to exogenous steroids with a depression in circulating LH. Negative feedback of gonadal steroids seems to be inoperative. In contrast, some females can show ovulatory surges of LH in response to mating (reflex ovulation), after administration of exogenous steroid (progesterone), and, on rare occasion, ovulation cycles occur spontaneously. Anatomical studies demonstrate that reproductive recovery is dependent on the outgrowth of GnRH axons to the host median eminence. Some but not all of the GnRH neurons within the grafts contribute to this innervation. GnRH axons exit into the host along well-defined pathways, recapitulating in part the paths taken by normal axons. How the graft and host are integrated to produce the panoply of reproductive responses is the subject of current study.

Clinical studies in black women with isolated gonadotrophin-releasing hormone deficiency.

Twelve black patients with primary amenorrhoea as a result of hypogonadotrophic hypogonadism were studied to establish the diagnosis of isolated gonadotrophin-releasing hormone (GnRH) deficiency. All were eunuchoid with poor development of breasts and pubic hair. Chromosomal complement was female and none had midline facial defects or anosmia. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were low or undetectable, while the levels of other pituitary hormones were normal. Patients did not respond to clomiphene citrate administration, but did bleed in response to an oestrogen/progestagen combination and responded to human menopausal gonadotrophin. This study clearly establishes that isolated GnRH deficiency occurs in black women and suggests that the male:female ratio is different from that in white populations.

Eye movement disorders in men with isolated hypogonadotropic hypogonadism.

The eye movement abnormalities in two men with isolated hypogonadotropic hypogonadism were studied clinically and electro-oculographically. Both demonstrated striking saccadic dysmetria. Subsequent neuroradiologic investigation confirmed atrophy of the cerebellar vermis in one of the patients. This is in concert with other midline structural abnormalities described in patients with isolated hypogonadotropic hypogonadism and suggests that this syndrome may arise from a genetically linked developmental abnormality of midline central nervous system structures.

Endorphins and the regulations of the human menstrual cycle.

In order to assess a possible influence of endogenous opioids upon gonadotrophin secretion in women, we examined the effects of i.v. administration of 10 mg naloxone, a specific opiate antagonist, in ten normal menstruating women, in thirteen women with amenorrhoea and/or hyperprolactinaemia and in two women with putative deficiency of gonadotrophin-releasing hormone (GnRH). In thirteen subjects, a saline vehicle control study (randomized order of administration) was also performed. In the normal women, naloxone failed to elicit changes in serum gonadotrophin levels when administered during the early follicular phase of the menstrual cycle. However, significant increments of LH were observed from 30 to 165 min following naloxone administration during the late follicular phase. Similar LH responses occurred in the amenorrhoeic and hyperprolactinaemic women. There was a tendency towards a concomitant increment in FSH levels, which reached statistical significance variably from 60 to 105 min post-naloxone. The LH response to naloxone in individual subjects showed a significant (P less than 0.01) quadratic (U-shaped) relationship to the log basal oestradiol concentration. No response to naloxone was observed in the two patients with GnRH deficiency despite a brisk response to an exogenous GnRH bolus. Taken together, these data suggest that central nervous system inhibitory opioid pathways may be involved in the regulation of LH secretion in normal women and that excessive production of endogenous opioids may play a role in the pathophysiology of some amenorrhoeic conditions.

Brain grafts reverse hypogonadism of gonadotropin releasing hormone deficiency.

Hypogonadism in the mutant hpg mouse is characterized by a deficiency of hypothalamic gonadotropin releasing hormone (GnRH). Affected male mice exhibit immature reproductive organs, small abdominal testes and low pituitary and plasma gonadotropin concentrations. Recent studies have demonstrated the potential of fetal brain transplants to establish functional connections with host tissues. We therefore sought to use this approach to correct the hpg deficit. Fetal preoptic area (POA) (a site of GnRH production) from unaffected animals of the hpg strain was transplanted into the anterior third ventricle of adult hpg mice. We report that in such implanted animals, killed 2 months post-implantation, the POA grafts contained GnRH neurones, from which GnRH-positive fibres could be traced to capillaries of the median eminence. Hypothalamic GnRH and pituitary and plasma gonadotropin concentrations were increased compared with levels in untreated (hpg) animals. The testes were enlarged and had descended into the scrotum. Evidence of full spermatogenesis and interstitial cell development was present in testicular sections. No such effects were seen with transplants of cortical tissue.

Endocrine studies in patients with isolated gonadotrophin-releasing hormone deficiency.

Twelve black women with isolated gonadotrophin deficiency were studied. After administration of intravenous gonadotrophin-releasing hormone (GnRH), all patients had subnormal gonadotrophin responses. However, after priming with subcutaneous GnRH (in 9 patients) follicle-stimulating hormone responses improved in 4 patients and luteinizing hormone responses in 7 patients. Prolactin responses to intravenous thyrotrophin-releasing hormone were significantly decreased at 20 and 60 minutes, when compared with reference subjects (P less than 0.01). In response to insulin-induced hypoglycaemia, prolactin responses were heterogeneous in 11 patients, while those of growth hormone were suboptimal in 8 of the 11 patients tested.

Pituitary and gonadal function in hypogonadotrophic hypogonadal (hpg) mice bearing hypothalamic implants.

GnRH receptor values are 30-50% of normal in pituitaries of hpg male mice, and testicular LH receptors only 8% of normal (160.4 +/- 17.6 and 2013 +/- 208.1 fmol/testis respectively). In male hpg mice bearing fetal preoptic area (POA) hypothalamic implants for 10 days there was no change in pituitary GnRH receptors, pituitary gonadotrophin content, or seminal vesicle weight. However, testicular weights and LH receptors were doubled in 4/10 mice and 2 had increased serum FSH levels. Between 26 and 40 days after implantation pituitary GnRH receptors and pituitary LH increased to normal male levels, although at 40 days serum and pituitary FSH concentrations had reached only 50% of normal values. Testicular and seminal vesicle weights increased more than 10-fold by 40 days after implantation and LH receptors to 70% of normal. In hpg female mice bearing hypothalamic implants for 30-256 days pituitary gonadotrophin concentrations were normal, even though GnRH receptors reached only 60% of normal values (6.18 +/- 0.4 and 9.8 +/- 0.4 fmol/pituitary respectively). Serum FSH was substantially increased from values of less than 30 ng/ml in hpg mice to within the normal female range in hypothalamic implant recipients. Ovarian and uterine weights increased after hypothalamic grafting from only 4-5% to over 74% of normal values. LH receptors increased from 6.5 +/- 1.3 fmol/ovary for hpg mice to 566.9 +/- 39.2 fmol/ovary for implant recipients. Vaginal opening occurred about 23 days after implantation and these animals displayed prolonged periods of oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth in children with a craniopharyngioma.

Although most children with craniopharyngiomas have multiple hormone deficiencies, some will have normal growth with hyperphagia and obesity postoperatively. Many later fail to maintain this growth. If growth hormone (GH) treatment is not instituted at this time, adult height will be compromised. Normal or accelerated growth following surgery does not indicate the presence of normal GH secretion nor insure continued growth. Children with this syndrome should have careful follow-up with accurate growth measurements so that GH replacement therapy can begin when indicated.