Gonadotropin-releasing hormone: one polypeptide regulates secretion of luteinizing and follicle-stimulating hormones

The similarity of FSH-releasing factor to lamprey gonadotropin-releasing hormone III (l-GnRH-III)

To validate further the existence of a specific hypothalamic follicle stimulating hormone releasing factor (FSHRF), stalk-median eminence (SME) fragments from sheep and whole hypothalami from male rats were purified by gel filtration on Sephadex G-25, and the gonadotropin-releasing activity on hemipituitaries of rats incubated in vitro was determined by bioassay and compared with the radioimmunoassayable luteinizing hormone releasing hormone (LHRH) and lamprey gonadotropin releasing hormone (l-GnRH) activities in the fractions. The FSH-releasing fractions eluted in the same sequence of tubes from the Sephadex column found earlier by in vivo bioassay and were clearly separated from the immunoassayable and bioassayable LHRH. The radioimmunoassay (RIA) for l-GnRH recognized equally l-GnRH-I and -III but had negligible cross-reactivity with LHRH. Fractionation of rat hypothalamic extract by gel filtration on Sephadex G-25 revealed three peaks of l-GnRH determined by RIA, all of which eluted prior to the peak of LHRH. Only the second peak had FSH-releasing but not LH-releasing activity. To determine if this FSH-releasing activity was caused by the presence of l-GnRH in the fraction, the pituitaries were incubated with normal rabbit serum or the l-GnRH antiserum (1:1000), and the effect on the FSH- and LH-releasing activity of the FSH-releasing fraction and the LH-releasing activity of LHRH was determined. The antiserum had no effect on basal release of either FSH or LH but eliminated the FSH-releasing activity of the active fraction without altering the LH-releasing activity of LHRH. Since l-GnRH-I has little activity to release FSH or LH, and its activity is nonselective, whereas previous experiments have shown that l-GnRH-III highly selectively releases FSH with a potency equal to that of LHRH to release LH, the results support the hypothesis that the FSH-releasing activity observed in these experiments was caused by l-GnRH-III or a closely related peptide.

Complementary deoxyribonucleic acid cloning, gene expression, and ligand selectivity of a novel gonadotropin-releasing hormone receptor expressed in the pituitary and midbrain of Xenopus laevis

We have cloned the full-length complementary DNA (cDNA) for a GnRH receptor from Xenopus laevis pituitary cDNA and determined its gene structure. The cDNA encodes a 368-amino acid protein that has a 46% amino acid identity to the human GnRH receptor. The X laevis GnRH receptor has all of the amino acids identified in the mammalian GnRH receptors as sites of interaction with the GnRH ligand. However, this receptor cDNA shares the same distinguishing structural features of the GnRH receptor that have been characterized from other nonmammalian vertebrates. These include the pair of aspartate residues in the transmembrane domains II and VII compared with the aspartate/asparagine arrangement in mammalian receptors, the amino acid PEY motif in extracellular loop III (SEP in mammals), and the presence of a carboxyl-terminal tail. Previous studies have reported that mammalian GnRH was equipotent to other naturally occurring GnRH subtypes in stimulating LH release from the amphibian pituitary. However, in this study we show that the X. laevis GnRH receptor has ligand selectivity for the naturally occurring GnRHs similar to other nonmammalian GnRH receptors. The order of potency of the GnRHs in stimulating inositol phosphate production in COS-1 cells transiently transfected with the X. laevis GnRH receptor cDNA was chicken GnRH II>salmon GnRH>mammalian GnRH. Transcripts of this GnRH receptor are expressed in the pituitary and midbrain of X. laevis.

Testosterone therapy in men: clinical and pharmacological perspectives

There is increasing evidence that androgen therapy in men may be effectively applied in several conditions to improve well being and health. Classical indications for androgen therapy in males are represented by primary or secondary hypogonadism, delayed puberty, aplastic anemia and that secondary to chronic renal failure, protein wasting diseases such as trauma, burns, tumors and infectious diseases. Androgen innovating applications in men are represented by aging and visceral obesity associated with the metabolic syndrome. In addition, it is clear that appropriate testosterone treatment can be adequately used in male contraception, provided spermatogenesis is abolished and tolerability is adequate. Due to unphysiological hormone levels achieved by currently available testosterone preparations, new delivery systems have been produced to achieve more physiological and sustained hormone levels and improve tolerability and action at the levels of target tissues. Some of them are now available in several countries and new formulas are under development.

LH-RH analogues: I. Their impact on reproductive medicine

In the 28 years that have passed since the elucidation of the structure of luteinizing hormone-releasing hormone (LH-RH), diverse clinical applications in the field of reproductive medicine and related fields have been established for agonists of LH-RH, based on inhibition of the pituitary-gonadal axis. Various clinical investigations with agonists of LH-RH in benign gynecologic disorders, polycystic ovary disease (PCOD), in vitro fertilization-embryo transfer (IVF-ET), benign prostatic hypertrophy (BPH), precocious puberty and contraception were reviewed. LH-RH antagonists inhibit LH, follicle-stimulating hormone (FSH), and sex steroid secretion immediately after their administration and thus achieve rapid therapeutic effects. LH-RH antagonists should find applications in the treatment of uterine leiomyomas, endometriosis, and in controlled ovarian stimulation-assisted reproductive techniques (COS-ART), which have been already established for the agonists. Modern LH-RH antagonists such as cetrorelix may prove superior to the agonists in COS-ART and also in the treatment of BPH, but additional studies in these and other areas are needed.

A historical perspective of the clinical evolution of the assisted reproductive technologies

The practice of assisted reproduction technology today is the result of the dedicated patient care, observation, research, and experimentation undertaken by previous generations of physicians. The building blocks of progress have been assembled over past decades, by scientists whose primary objective has been to push forward the frontiers of knowledge, in order to offer more effective methods of infertility treatment. And fortunately that process continues today. Amongst the many scientific developments that have led to the modern practice in assisted reproductive technology, a small number stand out as having had a unique importance. This historical review redraws the path through which in vitro fertilization went from an experimental to an accepted infertility treatment.

Joint basal and pulsatile hypersecretory mechanisms drive the monotropic follicle-stimulating hormone (FSH) elevation in healthy older men: concurrent preservation of the orderliness of the FSH release process: a general clinical research center study

To appraise the neuroendocrine mechanisms that underlie a selective (monotropic) elevation of serum FSH concentrations in healthy older men, we sampled blood in 11 young (ages 21-34) and 8 older men (ages 62-72) men every 2.5 min overnight. Serum FSH concentrations were quantitated in an automated, high-sensitivity, chemiluminescence-based assay. Rates of basal and pulsatile FSH secretion were estimated by deconvolution analysis, and the orderliness of the FSH release process via quantitated the approximate entropy statistic. Statistical analysis revealed that healthy older men manifest dual neuroendocrine hypersecretory mechanisims; specifically, a 2-fold increase in the basal (nonpulsatile) FSH secretion rate, and a concurrent 50% amplification of FSH secretory burst mass (and amplitude). The regularity or orderliness of ad seriatim FSH release is preserved in older individuals. We postulate that higher basal FSH secretion in older men is a consequence of reduced testosterone negative feedback, whereas amplified FSH secretory burst mass reflects net enhanced stimulation of gonadotrope cells by endogenous FSH secretagogues (e.g. GnRH and/or activin). The foregoing specific mechanisms driving heightened FSH secretion in older men contrast with the lower-amplitude pulsatility and more disorderly patterns of LH release in the same individuals. Thus, the present data illuminate an age-dependent disparity in the disruption of FSH neuroregulation in the aging male.

Effects of piperine on testis of albino rats

Piperine was administered to mature male albino rats at doses of 5 and 10 mg/kg body weight, p.o., respectively, for 30 days. Only a 10 mg dose of piperine treatment caused a significant reduction in the weights of testis and accessory sex organs. Histological studies revealed that piperine at a 5 mg dose caused partial degeneration of germ cell types, whereas at a 10 mg dose, it caused severe damage to the seminiferous tubule, decrease in seminiferous tubular and Leydig cell nuclear diameter and desquamation of spermatocytes and spermatids. Correlated to the structural changes, a fall in caput and cauda epididymal sperm concentrations was also evident. A 10 mg dose of piperine also caused a marked increase in serum gonadotropins and a decrease in intratesticular testosterone concentration, despite normal serum testosterone titres.

Origin and migration of luteinizing hormone-releasing hormone neurons in mammals

Luteinizing hormone-releasing hormone (LHRH) neurons are unique among hypothalamic neurons in that they originate outside of the central nervous system. In most vertebrates, LHRH-immunoreactive (-ir) neurons are detected in the epithelium of the medial olfactory pit soon after its formation. The LHRH-ir neurons migrate out of the placodal epithelium and into the brain along a migration route that consists of the central processes of the terminal, olfactory, and vomeronasal nerves. LHRH-ir cell migration follows a highly ordered course from the initial appearance of the LHRH-ir cells in the epithelium of the medial olfactory pit, to the crossing of these cells in cords on the nasal septum, to their entrance into the forebrain. Here they separate and follow an arching trajectory to their final destinations in the septal and preoptic areas and in the hypothalamus. Examination of the molecular makeup of the developing migration route reveals the presence of neural cell adhesion molecule (N-CAM) in non-LHRH-ir cells. The N-CAM-ir cells migrate into the nasal mesenchyme, trailed by N-CAM-ir axons of the olfactory, vomeronasal, and terminal nerves. These N-CAM cells and axons link the olfactory epithelia with the developing forebrain and together form scaffolding along which the LHRH-ir cells migrate into the brain. The focus of this review is on the origin and migration of LHRH-ir neurons in mammals, including humans. A discussion of Kallmann's syndrome (hypogonadotropic hypogonadism with anosmia) is included, in which there is an absence of LHRH-ir in the brain but clusters of LHRH-ir cells in the nasal cavity. This "experiment of nature" lends support to the hypothesis that all LHRH-ir cells in humans originate in the olfactory placode.

Luteinizing hormone-releasing hormone analogs: their impact on the control of tumorigenesis

The development of the luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists and the principles of their clinical use were reviewed. In the 28 years that have elapsed since the elucidation of the structure of LH-RH, various applications in gynecology, reproductive medicine, and oncology have been established for LH-RH agonists and antagonists. These clinical applications are based on inhibition of the pituitary and the gonads. The advantage of the LH-RH antagonists is due to the fact that they inhibit the secretion of gonadotropins and sex steroids immediately after the first injection and thus achieve rapid therapeutic effects in contrast to the agonists, which require repeated administration. LH-RH antagonists should find applications in the treatment of benign gynecologic disorders and benign prostatic hypertrophy and in assisted reproduction programs. The primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists, but antagonists like Cetrorelix already have been tried successfully. Antagonists of LH-RH might be more efficacious than agonists in treatment of patients with breast cancer as well as ovarian and endometrial cancer. Recently, practical cytotoxic analogs of LH-RH that can be targeted to LH-RH receptors on tumors have been synthesized and successfully tested in experimental cancer models. Targeted cytotoxic LH-RH analogs show a great promise for therapy of prostate, breast, and ovarian cancers.

Quantitative gonadotropin-releasing hormone gene expression and immunohistochemical localization in human endometrium throughout the menstrual cycle

GnRH is one of the paracrine/autocrine regulators of hCG secretion produced by the human trophoblast during pregnancy. We hypothesized that GnRH may play a role in the embryonic/endometrial dialogue during early implantation. To examine this hypothesis, we assessed GnRH and GnRH-receptor mRNA and protein expression in human endometrium throughout the menstrual cycle of premenopausal fertile patients. Quantitation of the mRNA was performed by reverse transcription (RT)-competitive polymerase chain reaction (PCR) in the presence of a competitive cDNA fragment. RT-PCR revealed that unfractioned endometrium and isolated endometrial stromal and epithelial cells express GnRH and GnRH-receptor mRNA throughout all phases of the menstrual cycle. Quantitative PCR showed a dynamic pattern in the GnRH mRNA expression throughout the cycle, with a significant increase (p < 0.05) in the secretory phase as compared to the proliferative phase. Furthermore, quantitative competitive PCR of isolated glandular and stromal cells showed higher mRNA levels (p < 0.05) in the luteal phase in both compartments. GnRH immunostaining was localized in all major compartments, with the most intense staining during the luteal phase. On the basis of these data, we suggest that during reproductive life, endometrial GnRH may play a paracrine/autocrine role in the early stages of implantation by modulating embryonic trophoblastic secretion of hCG.

Assessing sequential irregularity of both endocrine and heart rate rhythms

The quantification of subtle patterns in sequential data, and their changes, has considerable potential utility both in analysis of hormonal secretory dynamics, and of fetal heart rate rhythms. Approximate entropy, a recently developed statistic quantifying serial irregularity, has been applied in both these settings, and has yielded a number of new findings. Among endocrine applications, approximate entropy increases with increasing age for luteinizing hormone and follicle stimulating hormone, for both women and men, indicating greater irregularity (more apparently random dynamics) in the older groups; for the luteinizing hormone-testosterone axis, both irregularity and asynchrony increases accompany advancing age for men. These findings produce a means to potentially predict time until menopause onset, the efficacy of infertility drugs, and also provide firm quantitative support of a partial male menopause. In fetal monitoring, antepartum, and postnatal heart rate studies, approximate entropy consistently detected subtle shifts in heart rate rhythmicity, with greater regularity clinically corresponding to compromised physiology in all settings. Both the capability of approximate entropy to quantify rhythm changes undiscernible by auscultation, and a continuum interpretation linking per-individual antepartum, perinatal, and postnatal heart rate analyses provide considerable potential enhancement to the present clinical utility of fetal monitoring.

Follicle-stimulating hormone is secreted more irregularly than luteinizing hormone in both humans and sheep

Recently introduced statistical tools capable of discerning differences between the pattern of luteinizing hormone (LH) secretion and that of follicle-stimulating hormone (FSH) could be valuable in understanding ovulation and menopause, and ultimately in making diagnostic decisions and treating infertility and polycystic ovary syndrome. We assessed the validity and scope of the hypothesis that FSH is secreted more irregularly than LH in ewes and fertile women. We compared secretory irregularity of LH to that of FSH in both ovariectomized ewes (n = 7) and women of proven fertility (n = 5) during the follicular and luteal phases of their reproductive cycles. In each sheep, time series from both hypophyseal portal blood (HPB) and peripheral blood were evaluated in 72 samples obtained every 5 min; in each human, both luteal and follicular periods were studied in 192 samples obtained every 7.5 min. To quantify serial irregularity, we used approximate entropy (ApEn), a scale- and model-independent statistic. FSH secretion was consistently more irregular than that of LH in each subject. For sheep HPB, ApEn(FSH) = 1.415+/-0.097 was larger than ApEn(LH) = 0. 822+/-0.213, P < 0.0001 (mean+/-SD, paired t test). This difference persisted peripherally: ApEn(FSHper) = 1.431+/-0.101 > ApEn(LHper) = 1.252+/-0.086, P = 0.024. In women, ApEn(FSH) = 1.467+/-0.217 > ApEn(LH) = 0.923+/- 0.305, P < 0.0001. ApEn(FSH) > ApEn(LH) in 100% of women (peripheral) and sheep HPB. Secretion during the follicular phase was more irregular than during the luteal phase for both FSH and LH (P < 0.01). LH mean level secretion showed a wake/sleep difference in women, P < 0.005, with higher values awake. The consistency and statistical significance of these findings suggest that this LH/FSH difference may be broadly based within higher mammals. Ranges of normative and abnormal regularity values of LH, FSH, and their difference can be used in a number of settings, both (currently) research and (potentially ultimately) clinical milieus.

Gonadotropin secretion and development of ovarian follicles during oestrous cycles in heifers treated with luteinizing hormone releasing hormone antagonist

The hypothesis tested was that reduced LHRH stimulation of the anterior pituitary would lead to attenuated development of ovarian follicles as a result of reduced gonadotropin secretion during oestrous cycles of cattle. Twenty heifers were randomly assigned to be treated ( n = 5/treatment) with an antagonist to LHRH (LHRH-Ant) 1) from Day 2 to 7 (Day 0 = behavioural oestrus), 2) Day 7 to 12, 3) Day 12 to 17, 4) or serve as untreated control animals. LHRH-Ant suppressed LH pulses of heifers in all treatment groups from treatment initiation through Day 17 as compared with untreated control heifers [Peters et al., 1994. Luteinizing hormone has a role in development of fully functional corpora lutea (CL) but is not required to maintain CL function in heifers. Biol. Reprod., 51 (1994) 1248-1254]. Circulating concentration of FSH from Day 8 to 10 of the oestrous cycle did not increase in heifers treated with LHRH-Ant from Day 2 to 7 or Day 7 to 12; however, there was increased (P < 0.05) FSH from Day 8 to 10 of the oestrous cycle in heifers treated with LHRH-Ant from Day 12 to 17 and control heifers. Compared with control heifers, heifers treated with LHRH-Ant from the Day 2 to 7 had suppressed (P < 0.05) size and persistence of the first and second dominant ovarian follicles. Heifers treated with LHRH-Ant from Day 7 to 12 had suppressed size (P < 0.05 and tended (P < 0.10) to have a shorter persistence of the second dominant ovarian follicle compared with control heifers. Heifers treated with LHRH-Ant from Day 12 to 17 had a similar (P > 0.10) size and persistence of dominant ovarian follicles but had reduced (P < 0.10) numbers of large follicles compared with control heifers. Heifers treated with LHRH-Ant from Day 2 to 7 had lower (P < 0.01) concentrations of 17 beta-oestradiol during the treatment period and tended (P < 0.10) to have lower concentrations of 17 beta-oestradiol from Day 7 to 12 of the oestrous cycle compared with control heifers. Heifers treated with LHRH-Ant from Day 7 to 12 or Day 12 to 17 had similar (P > 0.10) circulating LH concentrations of l7 beta-oestradiol compared with control heifers. Reduced LHRH stimulation of the pituitary from Day 2 to 12 of the oestrous cycle and the resulting modulation in circulating LH and FSH led to suppressed ovarian follicular development and oestradiol secretion. After Day 12 of the oestrous cycle, reduced LHRH stimulation of the anterior pituitary did not lead to altered ovarian follicular development to the extent as reduced LHRH stimulation before Day 12 although pulsatile release of LH was similarly suppressed by treatment with the LHRH-Ant.

Preliminary study of ovarian activity in fillies treated with a GnRH vaccine

OBJECTIVE

To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old fillies.

DESIGN

A controlled vaccination dose rate experiment.

ANIMALS

Six 2-year-old Australian Stock Horse fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine.

RESULTS

Ovarian activity of the treated fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control fillies displayed oestrous activity and behaviour. Suppression of ovarian activity occurred for 25 and 30 weeks in the 200 and 400 mg groups, respectively. These differences were not significant. Ovarian activity ceased 2 to 3 weeks after primary vaccination. Antibody titres were low (330) until after the booster immunisation when they rapidly peaked at 22,000 and 28,000 in the 200 mg and 400 mg groups, respectively. Plasma progesterone concentrations of the treated fillies remained below 3.18 nmol/L while GnRH was suppressed. The vaccine had no significant effect on plasma androstenedione concentrations. Recovery from the effect of the vaccine was associated with development of ovarian follicles, normal oestrous behaviour and ovulation. Three of the four treated fillies and one of the controls conceived during the next breeding season and foaled normally. All the treated fillies conceived and produced normal foals in the following two breeding seasons.

CONCLUSION

Both dose rates suppressed ovarian function and prevented oestrous behaviour. These effects were reversible and the subsequent fertility of the vaccinated fillies was normal.

A hypothalamic follicle-stimulating hormone-releasing decapeptide in the rat

Previous studies indicated that there is a separate hypothalamic control of follicle-stimulating hormone (FSH) release distinct from that of luteinizing hormone (LH). An FSH-releasing factor (FSHRF) was purified from rat and sheep hypothalami, but has not been isolated. We hypothesized that FSHRF might be an analogue of mammalian luteinizing hormone-releasing hormone (m-LHRH) and evaluated the activity of many analogues of m-LHRH and of the known LHRHs found in lower forms. Here we demonstrate that lamprey (l) LHRH-III has a potent, dose-related FSH- but not LH-releasing action on incubated hemipituitaries of male rats. l-LHRH-I on the other hand, had little activity to release either FSH or LH. m-LHRH was equipotent to l-LHRH-III to release FSH, but also had a high potency to release LH in contrast to l-LHRH-III that selectively released FSH. Chicken LHRH-II had considerable potency to release both LH and FSH, but no selectivity in its action. Salmon LHRH had much less potency than the others tested, except for l-LHRH-I, and no selectivity in its action. Because ovariectomized, estrogen, progesterone-treated rats are a sensitive in vivo assay for FSH- and LH-releasing activity, we evaluated l-LHRH-III in this assay and found that it had a completely selective stimulatory effect on FSH release at the two doses tested (10 and 100 pmols). Therefore, l-LHRH-III is a highly potent and specific FSH-releasing peptide that may enhance fertility in animals and humans. It may be the long sought after m-FSHRF.

Steroid hormones and cancer: (III) observations from human subjects

Epidemiological evidence strongly suggests that steroid hormones are implicated in the risk of cancers of the breast, ovary and endometrium. However, it has proved difficult to implicate specific hormones or show that measurement of circulating hormones can identify women who will go on to develop malignant disease. There are, however, more convincing data that a proportion of established cancers are dependent upon steroid hormones for their continued growth and these underpin the use of endocrine manoeuvres in the treatment of these malignancies. Increased knowledge of the synthesis, release and mechanism of action of steroid hormones has led to the development of novel therapies for endocrine sensitive cancer and on-going research can reasonably be expected to identify tumour markers which can accurately predict hormone-dependency and provide better understanding of the mechanism by which response and resistance to therapy occur. The hope is that this knowledge will translate into more effective and rational endocrine treatment benefiting increased numbers of patients.

An urge to explain the incomprehensible: Geoffrey Harris and the discovery of the neural control of the pituitary gland

Geoffrey Harris is responsible for our view that the brain controls the endocrine system by an exquisitely regulated pattern of synthesis and release of individual members of a family of peptide hormones. These hormones are carried through a portal vascular system that passes from the hypothalamus to the pituitary gland, where they selectively regulate the secretion of the six anterior pituitary hormones. This family of hypothalamic hormones is highly conserved in all vertebrates, including humans. They are essential for all aspects of reproduction--courtship, mating, pregnancy and young rearing--and they are responsible for the seasonal regulation of breeding. The hypothalamic control mechanism for reproduction is sexually dimorphic, with a basic female pattern that becomes masculinized under the influence of specific steroid hormones acting during development. Other members of the hypothalamic hormone family specifically regulate the secretion of pituitary growth hormone and the anterior pituitary hormones controlling the functions of the thyroid and adrenal glands. The secretion of the hypothalamic hormones is itself regulated by the feedback of the target gland hormones (such as estrogen and progesterone), which concurrently act on the brain to elicit appropriate behavior patterns. The hypothalamo-hypophysial axis plays a crucial role in the struggle for the survival of the species. By bringing the endocrine system under the control of the brain, it allows access to external environmental inputs, learned behavior patterns, and the whole of the central integrative machinery needed for the bodily functions to be sensitively and optimally adapted to the ever-changing challenges and opportunities in the outside world.

Degradation kinetics of gonadorelin in aqueous solution

The degradation kinetics of gonadorelin were investigated systematically with reversed-phase high-performance liquid chromatography. The stability-indicating properties of this system were checked with photodiode array detection and by comparison with capillary zone electrophoretic analysis. Influences of gonadorelin concentration, pH, temperature, buffer ions, and ionic strength on the degradation kinetics were studied. The pH-log Kobs profile can be divided into three parts, a proton, a solvent, and a hydroxyl-catalyzed section, with different degradation products. These degradation products were characterized by mass using LC-MS. Gonadorelin is most stable at pH 5-5.5 with a half-life of 70 days at 70 degrees C. The overall degradation rate constant as a function of the temperature under acidic and alkaline conditions obeys the Arrhenius equation. The gonadorelin concentration and the concentrations of acetate, phosphate, borate, and carbonate buffer have no influence on the decomposition rate of the analyte. Increasing ionic strength led to higher Kobs at pH 2 and lower Kobs at pH 9, but influences were relatively small.

Down-regulation of pituitary receptors for luteinizing hormone-releasing hormone (LH-RH) in rats by LH-RH antagonist Cetrorelix

Antagonists of luteinizing hormone-releasing hormone (LH-RH), unlike the LH-RH agonists, suppress gonadotropins and sex steroid secretion immediately after administration, without initial stimulatory effects. [Ac-D-Nal(2)1,D-Ph(4Cl)2,D-Pal(3)3,D-Cit6,D-Ala10]LH-R H (SB-75; Cetrorelix) is a modern, potent antagonistic analog of LH-RH. In this study, the binding characteristics of receptors for LH-RH in membrane fractions from rat anterior pituitaries were investigated after a single injection of Cetrorelix at a dose of 100 microg per rat. To determine whether the treatment with Cetrorelix can affect the concentration of measurable LH-RH binding sites, we applied an in vitro method to desaturate LH-RH receptors by chaotropic agents such as manganous chloride (MnCl2) and ammonium thiocyanate (NH4SCN). Our results show that the percentages of occupied LH-RH receptors at 1, 3, and 6 h after administration of Cetrorelix were approximately 28%, 14%, and 10%, respectively, of total receptors. At later time intervals, we could not detect occupied LH-RH binding sites. Ligand competition assays, following in vitro desaturation, demonstrated that rat pituitary LH-RH receptors were significantly (P < 0.01) down-regulated for at least 72 h after administration of Cetrorelix. The lowest receptor concentration was found 3-6 h after Cetrorelix treatment and a recovery in receptor number began within approximately 24 h. The down-regulation of LH-RH binding sites induced by Cetrorelix was accompanied by serum LH and testosterone suppression. Higher LH-RH receptor concentrations coincided with elevated serum hormone levels at later time intervals. Our results indicate that administration of LH-RH antagonist Cetrorelix produces a marked down-regulation of pituitary receptors for LH-RH and not merely an occupancy of binding sites.

Identifiable Achatina giant neurones: their localizations in ganglia, axonal pathways and pharmacological features

1. An African giant snail (Achatina fulica Férussac), originally from East Africa, is now found abundantly in tropical and subtropical regions of Asia, including Okinawa in Japan. This is one of the largest land snail species in the world. The Achatina central nervous system is composed of the buccal, cerebral and suboesophageal ganglia. The 37 giant neurones were identified in these ganglia by the series of studies conducted over about 20 years. The identifications were made by the localization of these neurones in the ganglia, their axonal pathways and their pharmacological features. 2. In the left buccal ganglion, the four giant neurones, d-LBAN, d-LBMB, d-LBCN and d-LBPN, were identified. In the left and right cerebral ganglia, d-LCDN, d-RCDN, v-LCDN and v-RCDN were identified. The suboesophageal ganglia are further composed of the left and right parietal, the visceral, the left and right pleural, and the left and right pedal ganglia. In the right parietal ganglion, PON, TAN, TAN-2, TAN-3, RAPN, d-RPLN, BAPN, LPPN, LBPN, LAPN and v-RPLN were identified. In the visceral ganglion, VIN, FAN, INN, d-VLN, v-VLN, v-VAN, LVMN, RVMN and v-VNAN were identified. In the left parietal ganglion, v-LPSN was identified. In the left and right pedal ganglia, LPeNLN, RPeNLN, d-LPeLN, d-LPeCN, d-RPeAN, d-LPeDN, d-LPeMN and d-LPeEN were identified. 3. Of the small molecule compounds tested, dopamine, 5-hydroxytryptamine, GABA, L-glutamic acid, threo- or erythro-beta-hydroxy-L-glutamic acid were effective on the Achatina giant neurones. We suppose that these compounds act as the neurotransmitters for these neurones. 4. Of the neuroactive peptides, achatin-I(Gly-D-Phe-Ala-Asp). APGW-amide(Ala-Pro-Gly-Trp-NH2) and Achatina cardioexcitatory peptide (ACEP-1)(Ser-Gly-Gln-Ser-Trp-Arg-Pro-Gln-Gly-Arg-Phe-NH2) were proposed as neurotransmitters, because these were effective on the Achatina giant neurones and their presence was demonstrated in the Achatina ganglia. Further, myomodulin (Pro-Met-Ser-Met-Leu-Arg-Leu-NH2), buccalin (Gly-Met-Asp-Ser-Leu-Ala-Phe-Ser-Gly-Gly-Leu-NH2), FMRFamide (Phe-Met-Arg-Phe-NH2). [Ser2]-Mytilus inhibitory peptide ([Ser2]-MIP) (Gly-Ser-Pro-Met-Phe-Val-NH2), catch-relaxing peptide (CARP) (Ala-Met-Pro-Met-Leu-Arg-Leu-NH2), oxytocin (Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2) and small cardioactive peptideB (SCPB) (Met-Asn-Tyr-Leu-Ala-Phe-Pro-Arg-Met-NH2) could also be neurotransmitters because these peptides were also effective on the Achatina giant neurones, though their presence in the ganglia of this animal has not yet been demonstrated. 5. Calcium current (ICa) was recorded from Achatina giant neurones in the Na(+)-free solution containing K(+)-channel blockers under voltage clamp. The Ca2+ antagonistic effects of brovincamine, verapamil, eperisone, diltiazem, monatepil, etc., were compared using the ICa of the Achatina neurones. 6. Almost all of the mammalian small molecule neurotransmitters were effective on the Achatina giant neurones, suggesting that these compounds are acting on the neurones of a wide variety of animal species. However, the pharmacological features of the Achatina neurone receptors to these compounds were not fully comparable to those of the mammalian receptors. For example, we proposed that beta-hydroxy-L-glutamic acid (either threo- or erythro-) could be an inhibitory neurotransmitter for an Achatina neurone. 7. In contrast, the Achatina giant neurones appear to have no receptor for the mammalian neuroactive peptides, except for oxytocin and Arg-vasotocin. On the other hand, many neuroactive peptides were isolated from invertebrate nervous tissues, including achatin-I, a neuroexcitatory tetrapeptide having a D-phenylalanine residue.

Mechanisms of action of endocrine treatment in breast cancer

Endocrine treatment plays an important role in the therapy of breast cancer. While the basic mechanisms are understood, additional mechanisms may be of importance to their action and they may also contribute to the mechanism(s) of acquired resistance. Currently, several novel drugs are entering into clinical trials. Observations of the absence or presence of cross resistance to novel 'pure' steroidal antiestrogens and the non-steroidal tamoxifen may add important information to our understanding of the mechanisms of action of both classes of drugs. Similarly, exploration of different aromatase inhibitors in sequence or concert, as well as the combining of different endocrine treatment options may be warranted. Additionally, alterations in different biochemical parameters such as growth factors should not only be carefully explored in relation to treatment options but should also be followed during the course of treatment to asess alterations over time and in relation to the development of drug resistance.

Five decades of progress in management of the infertile couple

OBJECTIVE

To review milestones in the care of the infertile couple over the past five decades.

DATA RESOURCES

All issues of Fertility and Sterility were reviewed beginning with the first issue published in 1950 through volume 61, number 1 (January 1994). Other significant articles from the literature were reviewed as identified by directed Medline searches.

RESULTS

This historical review gives the reader a sense of the evolution of modern reproductive technology--how the past has shaped the present--through the development of modern surgical techniques, methods of ovulation induction, laparoscopy, ultrasound, endocrine assays, in vitro fertilization, cryopreservation of sperm and preembryos, and microscopic procedures on gametes and preembryos.

CONCLUSIONS

The remarkable capabilities of modern reproductive technologies are only possible because of the culmination of decades of innovative research.

Effect of leuprolide acetate in patients with moderate to severe functional bowel disease. Double-blind, placebo-controlled study

Moderate to severe functional bowel disease results in debilitating abdominal pain, nausea, intermittent vomiting, early satiety, bloating, abdominal distension, and/or altered bowel habits. Because it occurs approximately 20-30 times more frequently in women than in men and its symptoms often coincide with the menstrual cycle, we hypothesized that reproductive steroids may antagonize diseased nerves of the gastrointestinal tract, enhancing the expression of symptoms. No effective or consistent therapy has existed for these patients. We prospectively investigated the effect of a gonadotropin-releasing hormone analog, leuprolide acetate, in 30 women with symptoms of moderate to severe functional bowel disease. The study was phase II, randomized, double blind, and placebo controlled. Lupron Depot 3.75 mg (which delivers a continuous low dose of drug for one month) or placebo were given intramuscularly monthly for three months. Symptom scores were assessed at each four-week visit. Follicle-stimulating hormone, luteinizing hormone, estradiol, and progesterone levels were assessed before and after therapy. Patients treated with low-dose leuprolide improved progressively and significantly in scores for nausea, vomiting, bloating, abdominal pain, and early satiety, and for overall symptoms (P < 0.01-0.05). All hormone levels decreased significantly (P < 0.05) except luteinizing hormone (P = 0.054).

LHRH and cryptorchidism

This paper is a historic review of two studies of the treatment of cryptorchidism. One was concluded 20 years ago with native LHRH, while the other took place 14 years ago and involved one of the potent LHRH analogues. The first study was initiated at the end of 1971-at a time when the different modes of action of the decapeptide were by far not evaluated to the full extent they are now-and included ten prepubertal boys with undescended testes aged five to ten years. The treatment consisted of intramuscular application of 20 micrograms LHRH once daily for three weeks. Additionally, three boys, five, seven and nine years of age, also presenting undescended testes underwent an LHRH test with intravenous bolus application of 200 micrograms. In all three subjects, a 2.5-fold increase in plasma testosterone was observed 20 min after the bolus. The treatment group showed neither a rise in LH nor in testosterone at the end of therapy. Testicular descent was achieved in six out of six boys with bilateral and in 2/4 with unilateral undescended testes. These good results might be based on the fact that six boys had retractile rather than actually undescended testes. In the second study started in 1978, 18 boys, three to 12 years of age with either unilateral or bilateral cryptorchidism, were treated with a synthetic LHRH analogue ("D-Leu 6, Des-Gly-10 LHRH ethylamide") applied intranasally. The peptide prepared in an aqueous solution was administered in the form of nose drops.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical demonstration of neural cell adhesion molecule (NCAM) along the migration route of luteinizing hormone-releasing hormone (LHRH) neurons in mice

Contact between the developing forebrain and the ingrowing central processes of the olfactory, vomeronasal and terminal nerves is preceded by a migration of neural cell adhesion molecule (NCAM)-immunoreactive cells from the epithelium of the olfactory pit and the formation of an NCAM-immunoreactive cellular aggregate in the mesenchyme between the olfactory pit and the forebrain. The axons of the olfactory, vomeronasal, and terminal nerves, also NCAM-immunoreactive, grow into the cellular aggregate, which as development proceeds, becomes continuous with the rostral tip of the forebrain. The lateral and more rostral part of the cellular aggregate receives the ingrowing axons of the olfactory nerves and becomes the olfactory nerve layer of the olfactory bulb. The medial, more caudal part receives the central processes of the vomeronasal and terminal nerves. The vomeronasal nerve ends in the accessory olfactory bulb. The central processes of the terminal nerve end in the medial forebrain. Luteinizing hormone-releasing hormone (LHRH)-immunoreactive neurons, like the vomeronasal and terminal nerves, originate from the medial part of the olfactory pit. These LHRH cells migrate into the brain along and within a scaffolding formed by the NCAM-immunoreactive axons of the vomeronasal and terminal nerves, and they are never seen independent of this NCAM scaffold as they cross the nasal lamina propria. The results suggest that: (1) NCAM is likely to be necessary for scaffold formation, and (2) the scaffold may be essential for the subsequent migration of LHRH neurons into the brain. Because they aggregate, migrating LHRH-immunoreactive neurons, on which we did not detect NCAM immunoreactivity, may interact via other cell adhesion molecules (CAM). Inasmuch as the interaction between the LHRH-immunoreactive neurons and the NCAM-immunoreactive scaffold is heterotypic, the possibility of a heterophilic (NCAM to other CAM) interaction is not ruled out. These findings focus our attention on the functional role of NCAM in this migratory system.

Stimulatory and inhibitory effects of progesterone on FSH secretion by the anterior pituitary

The purpose of this study was to investigate whether progesterone exerted progesterone receptor mediated direct effects on the anterior pituitary in the secretion of FSH and whether such effects were mediated through the 5 alpha-reduction of progesterone. Treatment of anterior pituitary dispersed cells for 48 h with 0.5 nM estradiol reduced the ED50 for gonadotropin releasing hormone (GnRH)-stimulated FSH release from 0.58 to 0.36 ng/ml and the ED50 for GnRH-induced LH release from 0.54 to 0.19 ng/ml. When dispersed pituitary cells were treated with 0.5 nM estradiol and exposed to various doses of progesterone for 1 to 6 h, the most consistent rise in basal and GnRH-stimulated FSH release was observed with the 50 nM dose of progesterone with a 3-h exposure period. All three doses of progesterone elevated basal LH and GnRH-stimulated LH was increased by the 50 and 100 nM doses of progesterone during the 3-h period of treatment. Using the 50 nM dose of progesterone, basal and GnRH-stimulated LH was increased after 2, 3 and 6 h of progesterone treatment. When the period of exposure of progesterone was extended to 12, 36 or 48 h, there was a significant inhibition of GnRH-stimulated FSH release. GnRH-stimulated LH release was inhibited at 36 and 48 but not 12 h after progesterone treatment. These studies showed that the effect of progesterone administered for periods of 1 to 6 h enhanced the secretion of LH and FSH whereas progesterone administered for periods beyond 12 h inhibited FSH and LH release by dispersed pituitary cells in culture. These results are similar to those observed in vivo after progesterone treatment. Furthermore estrogen priming of the dispersed pituitary cells was necessary to observe the effects of progesterone. The progesterone antagonist RU486 prevented the progesterone-induced rise in GnRH-stimulated FSH release. Furthermore the 5 alpha-reductase inhibitor N,N-diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane- 17 beta-carboxamide also prevented the progesterone-induced rise in GnRH-stimulated FSH release in estrogen-treated dispersed pituitary cells. These results indicate that the anterior pituitary is a major site of action of progesterone in the release of FSH and that 5 alpha-reduction of progesterone plays an important role in FSH release.

The gonadotropin-releasing hormone (Gnrh) gene maps to mouse chromosome 14 and identifies a homologous region on human chromosome 8

The murine gonadotropin-releasing hormone (Gnrh) locus has been mapped to mouse chromosome 14 using a mouse x Chinese hamster somatic cell hybrid panel. The equivalent human locus, known as luteinizing hormone-releasing hormone (LHRH), has been previously mapped to 8p21-8p11.2. Four other loci mapping to the human chromosome 8 short arm have been mapped to mouse chromosome 8; two of these (PLAT, GSR) lie proximal to LHRH, and two (LPL, DEF1) lie distal to LHRH. The localization of Gnrh, the murine homolog of LHRH, to mouse chromosome 14 therefore defines a hitherto unrecognized block of homology between man and mouse. Furthermore, it indicates that the region of homology between the human chromosome 8 short arm and mouse chromosome 8 is composed of two separate blocks.

Migration of LHRH-immunoreactive neurons from the olfactory placode rationalizes olfacto-hormonal relationships

Nerve cells that express luteinizing hormone-releasing hormone (LHRH), essential for reproductive functions, originate in the epithelium of the medial olfactory placode. While the peripheral origin of this physiologically important brain peptide is surprising, associations between olfactory and reproductive systems are well documented in behavioral studies of pheromones and in clinical studies of disorders including hypogonadotropic hypogonadism with anosmia or olfactory-genital dysplasia. Mechanisms underlying this migration include a close association with neural cell adhesion molecules (NCAM), but are likely also to involve other physical and chemical factors.

Bidirectional saturable transport of LHRH across the blood-brain barrier

Systemic administration of luteinizing hormone-releasing hormone (LHRH) in rats has been found to influence behavior independently of pituitary or ovarian function. A previous study has shown that LHRH can cross the blood-brain barrier in one direction, but it was not known whether this was due to a saturable transport system. The rate of entry of 125I-labeled LHRH from blood to brain was determined by two different single-pass methods of carotid perfusion. The first, a multiple time point method, measures Ki from the slope of the linear regression when brain-to-blood ratios of radioiodinated LHRH are plotted against time. Saturable transport was determined by the difference between the Ki of rats perfused with 125I-LHRH (12.51 X 10(-3) mg.g-1.min-1) vs. rats perfused with 125I-LHRH and unlabeled LHRH (10 nmol/ml; 2.20 X 10(-3) ml.g-1.min-1). The inhibition by the unlabeled peptide was statistically significant (P less than 0.001). The second method, a single time point technique, measures the cerebrovascular permeability-surface area coefficient (PA). Saturable transport was determined in rats by the competition of unlabeled LHRH with 125I-LHRH. The PA value for 125I-LHRH (20.00 X 10(-3) ml.g-1.min-1) was significantly greater (P less than 0.05) than for 125I-LHRH with the addition of 10 nmol/ml unlabeled LHRH (4.14 X 10(-3) ml.g-1.min-1). Saturable transport of LHRH from brain to blood in mice was also determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of luteinizing hormone releasing hormone pulse characteristics on comparative luteinizing hormone and follicle stimulating hormone secretion from superfused rat anterior pituitary cell cultures

We have shown that 4 ng luteinizing hormone releasing hormone (LHRH) pulses induced significantly greater luteinizing hormone (LH) release from proestrous rat superfused anterior pituitary cells with no cycle related differences in follicle stimulating hormone (FSH). Current studies gave 8 ng LHRH in various pulse regimens to study amplitude, duration and frequency effects on LH and FSH secretion from estrous 0800, proestrous 1500 and proestrous 1900 cells. Regimen 1 gave 8 ng LHRH as a single bolus once/h; regimen 2 divided the 8 ng into 3 equal 'minipulses' given at 4 min intervals to extend duration; regimen 3 gave the 3 'minipulses' at 10 min intervals, thereby further extending duration: regimen 4 was the same as regimen 2, except that the 3 'minipulses' were given at a pulse frequency of 2 h rather than 1 h. In experiment 1, all four regimens were employed at proestrus 1900. FSH was significantly elevated by all 8 ng regimens as compared to 4 ng pulses; further, 8 ng divided into 3 equal 'minipulses' separated by 4 min at 1 and 3 h frequencies (regimens 2 and 4) resulted in FSH secretion that was significantly greater than with either a single 8 ng bolus (regimen 1) or when the 'minipulses' were separated by 10 min (regimen 3). In experiment 2, at proestrus 1500, FSH response to the second pulse of regimen 4 was significantly greater than in regimen 2; LH release was significantly suppressed at pulse 2 compared to regimen 2 accentuating divergent FSH secretion. At estrus 0800, FSH response to the second pulse of regimen 4 was significantly stimulated FSH at proestrus 1900, 1500 and estrus 0800, FSH divergence was most marked at proestrus 1500. These data indicate a potential role for hypothalamic LHRH secretory pattern in inducing divergent gonadotropin secretion in the rat.

Endocrine treatment for breast cancers: biological rationale and current progress

Endocrine therapy is a major treatment modality for the systemic management of breast cancer. In comparison with alternatives such as chemotherapy, hormone manipulations have the advantage of lower toxicity but suffer from the disadvantages of producing responses in only 30-40% of patients with metastatic disease and seldom being curative. Nevertheless in recent years there have been significant advances in the endocrine treatment of breast cancer which have stemmed from a better understanding of the sources from which breast tumours may be supplied with hormones, the mechanism by which hormones regulate tumour proliferation and the more accurate identification of hormone sensitive tumours. As a result agents such as antioestrogens, aromatase inhibitors. LHRH agonists have largely superseded surgical and radiological ablation of endocrine organs. The major reduction in morbidity associated with these medical regimes means that they are much more acceptable to patients and may be used as adjuvants to local treatment of the breast in patients with "earlier" stages of the disease. At the same time patients can now be offered rational treatment selected on the basis of tumour biology rather than on more empirical criteria. The aims of this review are to provide details of the research which has led to this progress in endocrine treatment of breast cancer and to put into perspective the prospects for further advances.

The migration of luteinizing hormone-releasing hormone (LHRH) neurons from the medial olfactory placode into the medial basal forebrain

Over the years, investigators have noticed, in a wide variety of species of vertebrates, large numbers of cells migrating from the olfactory placode to the forebrain. These cells were considered to be Schwann cells or ganglion cells of the terminalis nerve. Recently, immunocytochemical localization studies have shown that many of these migrating cells contain luteinizing hormone-releasing hormone (LHRH), a brain peptide that regulates reproductive functions by evoking the release of luteinizing hormone and follicle-stimulating hormone from the anterior pituitary gland. The origin of LHRH cells in the epithelium of the medial olfactory placode, their migration across the nasal septum and into the forebrain, with branches of the terminalis nerve, also a derivative of the medial part of the olfactory placode, has led to some interesting speculations, from evolutionary and physiological perspectives, about the origin of these cells and the role of the terminalis nerve in their migration.

Induction of ovulation with pulsatile GnRH

The use of pulsatile GnRH to treat infertile women who do not ovulate has been shown to be safe, simple, and effective and the preferred method of inducing ovulation in appropriately selected patients who are resistant to treatment with clomiphene citrate. Treatment with GnRH is particularly effective for restoring ovulation in patients with idiopathic hypogonadotrophic hypogonadism and partially recovered weight-related amenorrhoea, but less successful in patients with polycystic ovary syndrome and organic hypothalamic pituitary disease. Based on personal experience, we advocate routine use of the subcutaneous route, using 15 micrograms per pulse every 90 min, and we monitor the patient's progress by serial ultrasound scanning and measurement of serum gonadotrophin and oestradiol concentrations. If the patient does not respond we recommend adding treatment with clomiphene citrate (Homburg et al, 1988b). Treatment with intravenous GnRH is reserved for women who do not respond to the above combination of drugs. We do not treat patients with GnRH until their body mass index is in the normal range (between 20-25) and we avoid GnRH treatment in patients with hypersecretion of LH during the follicular phase. If LH concentrations are raised, an alternative method of treatment is recommended, such as ovarian diathermy (Armar et al, 1990). Finally, the question of whether GnRH deficiency in patients with hypogonadotrophic hypogonadism is caused by a specific genetic lesion is not yet fully resolved. Yang-Feng et al (1986) used a cDNA clone encoding the human GnRH precursor molecule in order to assign the GnRH gene to a particular human chromosome. They found a single site for GnRH sequences in the human genome and that the gene coding for GnRH is located on the short arm of chromosome 8. Experiments in the congenitally hypogonadal mouse have shown that it is possible to restore gonadal development and gametogenesis by gene transfer (Mason et al, 1987). Clearly an abnormality at the level of the genome may be responsible for the secretory defect in patients with hypogonadotrophic hypogonadism, but it has yet to be defined (Weiss et al, 1989). Presumably elucidation awaits the development of more refined methods because both the genetics and the clinical associations of GnRH deficiency are most persuasive. Meanwhile replacement treatment with GnRH provides a simple and safe form of treatment for managing the clinical syndromes of GnRH deficiency.

Basic and clinical aspects of GnRH-agonists in reproduction

Within recent years GnRH agonists have gained increasing importance in the treatment of reproductive failure. Their use as a pretreatment for in vitro fertilization increases the pregnancy rate at least under certain conditions. In cases of endometriosis and uterus myomatosus, GnRH agonists achieve high remission rates and may avoid or at least postpone the need for surgical intervention. The physiological basis and current clinical strategies are discussed.

Alternate regimens for ovulation induction in polycystic ovarian disease

The patient with PCOD remains a challenge to the reproductive endocrinologist. Although successful induction of ovulation can often be achieved using standard therapeutic regimens of CC or hMG, too often this group of anovulatory patients fails to respond as expected. Over the past 10 to 15 years, alternate approaches to ovulation induction have been investigated with encouraging results. Whereas no one method is productive in all patients, these varied regimens offer us a number of options in dealing with this difficult clinical problem.