Effects of apelin on reproductive functions: relationship with feeding behavior and energy metabolism

Apelin is an adipose tissue derived peptidergic hormone. In this study, 40 male Sprague-Dawley rats were used (four groups; n = 10). Apelin-13 at three different dosages (1, 5 and 50 μg/kg) was given intraperitoneally while the control group received vehicle the same route for a period of 14 days. In results, apelin-13 caused significant decreases in serum testosterone, luteinizing hormone and follicle-stimulating hormone levels (p < 0.05). Administration of apelin-13 significantly increased body weights, food intake, serum low-density lipoprotein and total cholesterol levels (p < 0.05), but caused significant decreases in high-density lipoprotein levels (p < 0.05). Serum glucose and triglyceride levels were not significantly altered by apelin-13 administration. Significant decreases in both uncoupling protein (UCP)-1 levels in the white and brown adipose tissues and UCP-3 levels in the biceps muscle (p < 0.05) were noted. The findings of the study suggest that apelin-13 may not only lead to obesity by increasing body weight but also cause infertility by suppressing reproductive hormones.

Functional Characterisation of Eel Dopamine D2 Receptors and Involvement in the Direct Inhibition of Pituitary Gonadotrophins

In various vertebrate species, dopamine (DA) exerts an inhibitory action on reproduction. In the European eel, DA plays a pivotal role in the inhibitory control of gonadotroph function and the blockade of puberty. In vivo studies have suggested that this effect is mediated by receptors pharmacologically related to the D2 family. In the European eel, two distinct D2 receptor (D2-R) paralogous genes have been identified (D2A-R and D2B-R) and both were shown to be expressed in the pituitary. We investigated the potential role of each paralogue in the control of gonadotroph function in this species. Eel recombinant D2A-R or D2B-R were expressed in HEK 293 cells, with a universal Gα subunit, and receptor activation was followed by inositol phosphate production. Recombinant D2-Rs exhibited a comparable affinity for DA, although they had differential affinities for mammalian D2-R agonists and antagonists, supporting subtle structure/activity differences. Furthermore, using eel pituitary cell primary cultures, the expression by gonadotroph cells of both native eel D2-R paralogues was examined by in situ hybridisation of D2A-R or D2B-R transcripts, coupled with immunofluorescence of luteinising hormone (LH)β or follicle-stimulating (FSH)β. LH and to a lesser extent, FSH cells expressed both D2-R transcripts but with a clear predominance of D2B-R. Notably, D2B-R transcripts were detected for the majority of LH cells. Accordingly, using these cultures, we showed that DA potently inhibited basal and testosterone-stimulated LHβ expression and less potently basal and activin-stimulated FSHβ expression. We also tested some D2-R antagonists, aiming to select the most adequate one to be used in innovative protocols for induction of eel sexual maturation. We identified eticlopride as the most potent inhibitor of DA action on basal and stimulated LH expression in vitro. Our data suggest a differential functionalisation of the duplicated receptor genes and demonstrate that mainly D2B-R is involved in the dopaminergic inhibitory control of eel gonadotroph function.

The effects of opiate consumption on serum reproductive hormone levels, sperm parameters, seminal plasma antioxidant capacity and sperm DNA integrity

We evaluated the effects of opiate consumption on semen quality, sperm function, seminal plasma antioxidant capacity, and sperm DNA integrity. A total of 142 opiate addict men (group 1) were enrolled in the study and 146 healthy age matched male volunteers (group 2) served as controls. Two semen analyses were performed in all participants. Sperm chromatin structure assay (SCSA) was used to identify sperm DNA integrity. The mean±SD sperm concentration in opiate users and in control subjects was 22.2±4.4 and 66.3±8.3 million per ml, respectively (P=0.002). A significant increase in the amount of fragmented DNA was found in opiate consumers compared with that in controls (36.4±3.8% vs. 27.1±2.4%, P=0.004). Significantly decreased levels of catalase-like and superoxide dismutase-like (SOD) activity were observed in group 1 compared with group 2. Opiate consumption has significant adverse effects on semen quality. In cases of unexplained infertility in men, opium consumption should be considered as a possible factor.

The role of kisspeptin and gonadotropin inhibitory hormone in the seasonal regulation of reproduction in sheep

Sheep are seasonal breeders, experiencing an annual period of reproductive quiescence in response to increased photoperiod during the late-winter into spring and renaissance during the late summer. The nonbreeding (anestrous) season is characterized by a reduction in the pulsatile secretion of GnRH from the brain, in part because of an increase in negative feedback activity of estrogen. Neuronal populations in the hypothalamus that produce kisspeptin and gonadotropin-inhibitory hormone (GnIH) appear to be important for the seasonal shift in reproductive activity, and the former are also mandatory for puberty onset. Kisspeptin cells in the arcuate nucleus (ARC) and preoptic area appear to regulate GnRH neurons and transmit sex-steroid feedback signals to these neurons. Moreover, kisspeptin expression in the ARC is markedly up-regulated at the onset of the breeding season, as too are the number of kisspeptin fibers in close apposition to GnRH neurons. The lower levels of kisspeptin seen during the nonbreeding season can be "corrected" by infusion of kisspeptin, which causes ovulation in seasonally acyclic females. The role of GnIH is less clear, but mounting evidence supports a role for this neuropeptide in the inhibitory regulation of both GnRH secretion and gonadotropin release from the pituitary gland. Contrary to kisspeptin, GnIH expression is markedly reduced at the onset of the breeding season. In addition, the number of GnIH fibers in close apposition to GnRH neurons also decreases during this time. Importantly, exogenous GnIH treatment can block both the pulsatile release of LH and the preovulatory LH surge during the breeding season. In summary, it is most likely the integrated function of both these neuropeptide systems that modulate the annual shift in photoperiod to a physiological change in fertility.

Antigonadotropins: a novel strategy to halt Alzheimer's disease progression

A significant amount of research has been focused on the relationship between hormones and Alzheimer's disease. However, the majority of this work has been on estrogen and more recently testosterone. A serendipitous patient encounter led one of us (RLB) to question whether other hormones of the hypothalamic-pituitary-gonadal axis could be playing a role in the pathogenesis of Alzheimer's disease. The age-related decline in reproductive function results in a dramatic decrease in serum estrogen and testosterone concentrations and an equally dramatic compensatory increase in serum luteinizing hormone concentrations. Indeed, there is growing evidence that the gonadotropin, luteinizing hormone, which regulates serum estrogen and testosterone concentrations, could be an important causative factor in the development of Alzheimer's disease. This review provides information supporting the "gonadotropin hypothesis," puts forth a novel mechanism of how changes in serum luteinizing hormone concentrations could contribute to the pathogenesis of Alzheimer's disease, and discusses potential therapeutic anti-gonadotropin compounds.

Beyond Estrogen: Targeting Gonadotropin Hormones in the Treatment of Alzheimers Disease

Based on epidemiological and observational studies, estrogen and hormone-replacement therapy were until recently viewed as major factors in the prevention of Alzheimer's disease (AD). However, a recent randomized clinical trial revealed that hormone replacement therapy using estrogen plus progestin may actually exacerbate the incidence of dementia when administered to elderly women. These contradictory reports have cast grave doubt on the role of estrogen in disease pathogenesis and led us to consider an alternate hypothesis that would be consistent with both observations. Specifically, we suspect that hormones of the hypothalamic pituitary gonadal axis such as gonadotropins, that are regulated by estrogen (or in males by testosterone), are involved in the pathogenesis of Alzheimer's disease. One such gonadotropin, luteinizing hormone (LH), is significantly elevated in both the sera and brain tissue of patients with AD and leads to an increased production of amyloid-beta. Importantly, a key role in disease pathogenesis is further supported by the fact that the distribution of neuronal receptors for LH parallels those populations of neurons that degenerate during the course of the disease. That gonadotropins, not estrogen nor testosterone, mediate disease pathogenesis has led to a paradigm shift, not only for the treatment of AD but a wide variety of other age-related diseases. Therefore, the effects of agents that abolish LH, such as leuprolide acetate, which are currently being evaluated in Phase II clinical trials for the treatment of AD, are eagerly anticipated.

Acute goserelin administration inhibits gonadotropin and androgen secretion in post-menopausal women with ovarian hyperandrogenism

The aim of this study was to verify the effect of goserelin, a GnRH agonist, in women with post-menopausal virilization. Six patients with post-menopausal virilization and increase in 17-hydroxyprogesterone (17-OHP), total (TT) and free testosterone (FT) levels underwent single subcutaneous administration of goserelin, 3.6 mg. Serum 17-OHP, TT, FT, LH, FSH, E2, delta4 and 3alpha-andro-stanediol glucuronide levels were measured before and 4, 8 and 18 days after goserelin administration. Goserelin administration was followed by progressive inhibition of FSH and LH, which fell to premenopausal levels on day 18, and progressive normalization of androgen parameters. The low E2 levels recorded at baseline were further reduced by goserelin administration. Four patients then underwent ovariectomy while in two patients, rejecting surgical treatment, goserelin treatment was protracted up to 6 and 12 months, respectively, with remission of hyperandrogenism. This study shows that in post-menopausal patients with virilization GnRH agonist allows to confirm the diagnosis of gonadotropin-dependent ovarian hyperandrogenism: its administration induces inhibition of gonadotropin levels, normalization of androgen parameters, and remission of virilization when the treatment is protracted in patients waiting for surgery.

Approaches to define the role of SF-1 at different levels of the hypothalamic-pituitary-steroidogenic organ axis

Targeted gene disruption has produced knockout mice lacking the orphan nuclear receptor steroidogenic factor 1 (SF-1). These SF-1 knockout mice lacked adrenal glands and gonads, resulting in adrenocortical insufficiency and sex reversal of their internal and external genitalia. They also had impaired expression of pituitary gonadotropins and agenesis of the ventromedial hypothalamic nucleus (VMH), confirming roles of SF-1 at multiple levels of the hypothalamic-pituitary-steroidogenic tissue axis. Using the Cre-loxP system, we now have generated mice in which SF-1 is inactivated selectively in the anterior pituitary. These pituitary-specific SF-1 knockout mice were sterile and failed to exhibit sexual maturation. Histologically, their gonads were markedly hypoplastic, weighing only approximately 5% of the gonads of wild-type mice. Consistent with an important role of SF-1 in gonadotropes, there were no cells in the pituitary gland that expressed either follicle-stimulating hormone (FSH) or luteinizing hormone (LH). These pituitary-specific SF-1 knockout mice are a novel genetic model of hypogonadotropic hypogonadism and establish essential roles of SF-1 in gonadotropin expression.

[Gonadotrophin-releasing hormone antagonists: application in ovary-stimulating and sex-steroid dependent disorders]

The hypothalamic gonadotrophin-releasing hormone (GnRH) stimulates synthesis and secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) by the gonadotrophic cells of the pituitary. The mechanisms of action of GnRH antagonists and of agonists is completely different. Due tot competitive blockage of GnRH receptors by antagonist administration, LH (and to a lesser extent FSH) levels drop rapidly. Moreover pituitary function normalizes immediately following cessation of medication. The direct and rapid action of GnRH antagonists, the dose dependent suppression of LH and FSH and the rapid restoration of hypophyseal function after cessation of the use of antagonists may shorten and simplify in-vitro fertilization, with less chance of side effects or complications. Further studies are required to decide whether antagonists can usefully be applied for other gynecological indications such as the polycystic ovary syndrome. The possibilities of profitable long term treatment will increase considerably if it proves possible to develop a sustained action formulation.

Hormonal contraception in the male

The hormonal approach to male contraception is based on the suppression of gonadotrophin secretion with secondary suppression of spermatogenesis. This can be achieved by administration of testosterone or other androgen alone, but combined administration with a progestogen or GnRH analogue allows the dose of testosterone to be reduced to physiological replacement doses. This approach has been investigated for many years but without identification of a regimen which results in sufficient suppression of spermatogenesis to provide ensured contraception in all men, safely and conveniently. The reasons for this are discussed, and recent developments towards a regimen that fulfills all these criteria are described. Crucial to development of any new product is that it will be used: surveys of both men and women indicate firmly positive attitudes towards a 'male pill'. There are, therefore, grounds for cautious optimism that the next decade may see the introduction of the first novel male contraceptive for several hundred years.

Pituitary gonadotrophin inhibition by subcutaneously administered steroids

The anti-gonadotrophic activity of various new steroids was assessed by a parabiosis assay method using a normal female and a castrated male rat. 4-Chloro-17α-methyl-19-nortestosterone and 2α-methyl-17β-hydroxy-19-norandrostan-3-one showed a relatively high anti-pituitary activity and a high levator ani effect, while the stimulation of the seminal vesicles and prostate were minimum. 2α-Fluoro-17α-ethynyltestosterone and 2-benzoyloxymethylene-17α-methyl-17-β-hydroxyandrostan-3-one possess a disproportionately high anti-pituitary activity.

The anti-gonadotropic effects of cytokines: the role of neuropeptides

The inhibitory effect of inflammation and endotoxins on the secretion of reproductive hormones from the hypothalamo-pituitary axis is well documented. A comparison of the luteinizing hormone (LH) suppressing effects of several pro-inflammatory cytokines revealed that centrally administered IL-1 beta was the most potent inhibitor of pituitary LH secretion; interleukin (IL)-1 alpha and tumor necrosis factor (TNF) alpha were relatively less effective, whereas IL-6 was ineffective. This order of potency suggested that the anti-gonadotropic effects of an immune challenge are most likely attributable to the action of centrally released IL-1 beta, and this was supported by the demonstration that IL-1 beta suppressed hypothalamic luteinizing hormone releasing hormone (LHRH) release. We used a multifaceted approach to identify the afferent signals in the brain that convey immune messages to hypothalamic LHRH neurons. Pharmacological studies with specific antagonists of opioid receptor subtypes demonstrated that activation of the mu 1 receptor subtype was required to transmit the cytokine signal. Furthermore, icv IL-1 beta upregulated hypothalamic POMC mRNA and increased the concentration and release of beta-endorphin, the primary ligand of mu 1 receptors. We have obtained evidence that IL-1 beta also enhanced the gene expression and concentration of tachykinins, a family of nociceptive neuropeptides in the hypothalamus. Blockade of tachykinergic NK2 receptors attenuated IL-1 beta induced inhibition of LH secretion. Collectively, these results demonstrate that IL-1 beta, generated centrally in response to inflammation, upregulates the opioid and tachykinin peptides in the hypothalamus. These two groups of neuropeptides are critically involved in relaying the cytokine signal to neuroendocrine neurons and causing the suppression of hypothalamic LHRH and pituitary LH release.

Effect of salmon gonadotropic hormone on sex steroids in male rainbow trout: plasma levels and testicular secretion in vitro

Male rainbow trout were treated with salmon gonadotropic hormone (GTH) at different stages of the circannual reproductive cycle; spawning fish were also treated with an antiserum against salmon GTH. Injection of GTH led to a several-fold increase of plasma sex steroid levels during spermatogenesis and in the spawning season but was without effect at early stages of testicular development. GTH neutralization during the spawning season was followed by a several-fold decrease of plasma sex steroid levels. During spermatogenesis and in the spawning season, both treatment regimes resulted in an increased sensitivity of testicular explants in response to a subsequent stimulation of steroid secretion in vitro. This up-regulatory response may facilitate and maintain the high sex steroid plasma levels observed during the spawning season. It may also be necessary to allow for concomitant peak values of plasma GTH and sex steroids in the spawning season, a situation difficult to understand within the negative feedback concept. The adaptive capacities of the testicular steroidogenic system indicate that it is not only an effector site for GTH but also an active part of the endocrine system controling reproduction.

[Evaluation of danazol treatment of women with fibrocystic disease of breast]

The results of treatment of 20 female patients with fibrocystic degeneration of the breast with danazol are discussed. Diagnosis was made with the aid of mammography. Danazol was administered in the dose of 200 mg twice a day for 2 months, followed by 100 mg thrice a day, and 100 mg twice a day for further 2 months. An improvement in the clinical symptoms, decrease in LH, FSH, estradiol and progesterone levels was produced by danazol. The drug did not change LH response to LH-RH stimulation while blockade of dopaminergic receptors with metoclopramide decreased PRL response.

The effect of gonadotropin suppression on the induction of ovulation in premature ovarian failure patients

Ovulation induction in patients with hypergonadotropic premature ovarian failure is rarely successful. The authors have attempted to reproduce the results of recent case reports that suggest that ovulation and pregnancy can be successfully achieved when estrogen therapy precedes or coincides with ovarian stimulation with human menopausal gonadotropins (hMG). Fourteen patients with idiopathic premature ovarian failure underwent gonadotropin suppression and attempted ovulation induction with at least one of three regimens, which were as follows: 1) Group A: estrogen-induced suppression followed by hMG stimulation (n = 4). 2) Group B: estrogen-induced suppression followed by hMG stimulation with concomitant estrogen therapy (n = 10). 3) Group C: gonadotropin-releasing hormone agonist-induced gonadotropin suppression followed by concomitant hMG stimulation (n = 6). Despite complete gonadotropin suppression and high-dose hMG therapy in all three groups, ovulation occurred in only a single patient in group C. Pregnancy did not ensue. These data fail to corroborate previous case reports.

Antigonadotropic activity of pineal gland of the Indian palm squirrel Funambulus pennanti

Bioassay of the pineal extract of F. pennanti was performed in immature female mice which was previously sensitized with human chorionic gonadotrophin. Reduction of ovarian and uterine weights indicated an antigonadotropic nature of the pineal gland of this animal.

The metabolism of 19-nor contraceptive progestins modulates their biological activity at the neuroendocrine level

In this communication, a series of studies from our laboratory dealing with the mechanism of action of 17 alpha-ethinyl derivatives of 19-nor testosterone are reviewed. The administration of norethisterone (NET) to long-term castrated female rats induces the nuclear translocation of pituitary estradiol receptors and is followed by some estrogenic-like effects at the hypothalamic-pituitary unit. It is established that an A-ring reduced metabolite of NET, the 3 beta,5 alpha-tetrahydro NET derivative, is responsible for the observed in vivo estrogenic effects of the parent compound. 3 beta,5 alpha-NET binds to the estrogen receptor and is efficient in inducing the pituitary estrogen-dependent progesterone receptor and in increasing the uterine weight in long-term castrated rats. Furthermore, administration of 3 beta,5 alpha-NET and the 5 alpha-reduced metabolite of NET (5 alpha-NET) are able to inhibit the release of gonadotropins in the castrated animal to a greater extent than NET. Moreover, pretreatment with tamoxifen, an estrogen binding site competitor, results in a significant diminution of the antigonadotropic potency of 3 beta,5 alpha-NET but not of the 5 alpha-NET, which is only inhibited by the administration of cyproterone acetate. These findings underline the importance of the metabolic rate of NET for the expression of its biological effects at the hypothalamic-pituitary unit.

[Hypothalamic factors: current findings]

The last few years have seen the isolation, characterization and synthesis of two new hypothalamic peptides, the growth-hormone releasing factor (GRF) and the corticotrophin-releasing factor (CRF). GRF selectively stimulates pituitary growth hormone. It is interesting to note that GRF was isolated from two pancreatic tumors which were responsible for an acromegalic condition in the two patients. Hypothalamic GRF (1-44) has been found to be identical to this pancreatic GRF. CRF was isolated first from ovine hypothalamus and later characterized in several species and in the human. CRF specifically stimulates the secretion of ACTH and of beta-endorphins, and other fragments of the common precursor named pro-opiomelanocortin. Chemical synthesis of analogues of hypothalamic peptides, and in particular of GnRH (gonadotrophin-releasing hormone), has made available new molecules which form agonists as well as antagonists. After a short period of gonadotrophin stimulation GnRH agonists induce desensitization of the pituitary and a decrease in secretion of the gonadotrophins and the sex steroids by the gonads. Their usefulness is presently being tested in several conditions such as prostate cancer, endometriosis, breast cancer and idiopathic precocious puberty, and as a contraceptive method. On the other hand, pulsatile administration of GnRH restores deficient reproductive functions in certain conditions such as anovulation or azoospermia.

Male fertility regulation: recent advances

Acceptable antifertility drugs for men are proving difficult to produce. Such drugs must aim to achieve complete azoospermia over a long period. This requirement may be relaxed only if it can be shown that the residual sperm produced by men whose spermatogenesis has been suppressed by antifertility drugs to oligospermia are incapable of fertilizing ova. Hormonal methods involving suppression of the secretion of gonadotrophin hormones by the pituitary gland invariably require androgen supplementation, and the use of steroids either alone or in combination requires careful monitoring for their side-effects. A chemical (non-hormonal) approach involving the incapacitation of sperm in the epididymis has been shown to be feasible in animal studies using alpha-chlorohydrin and 6-chloro-6-deoxy sugars, although such compounds cannot be developed for human use because of their toxicity. Immunological approaches have the inherent problem of delivery of the antibody to the target. While the search for new and safer chemical and hormonal approaches goes on, the recent evidence that vasectomy offers a safe surgical option leaves responsible men with some choice to add to the condom.

Nuclear translocation of estradiol receptors by the in vivo administration of norethisterone: an alternate mechanism for gonadotropin inhibition

In order to investigate the anti-gonadotropic effect of norethisterone (NET) in long-term ovariectomized rats, we studied the interaction of this synthetic progestin with intracellular steroid receptors in the anterior pituitary by a nuclear exchange assay. The results demonstrated that the administration of NET to long-term ovariectomized rats resulted in nuclear translocation of estradiol cytosol receptors in the pituitary and uterus with a rate of accumulation and nuclear retention being similar in both tissues. Accumulation of nuclear estradiol receptors in the pituitary was in agreement with the rate of LH inhibition in NET-treated rats. The results presented in this communication may explain the anti-gonadotropic activity of NET in long-term ovariectomized rats in addition to its well known progestational activity.

Premature ovarian failure: a search for circulating factors against gonadotropin receptors

Nine patients with premature ovarian failure, one of whom had the associated autoimmune disorders rheumatoid arthritis, Hashimoto's thyroiditis, and vitiligo, were examined for the presence of a serum factor which would interfere with gonadotropin-receptor interaction in a bovine testicular membrane system. Sera from nine premenopausal and nine postmenopausal women served as control subjects. Mean displacement of radiolabeled follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from receptors was not significantly different among the three groups. However, the greatest interference with FSH-receptor interaction was detected in the patient with both premature ovarian failure and autoimmune diseases. No differences in mean serum levels of IgG, IgM, and IgA were found among the premature ovarian failure and the two control groups, nor were immunoglobulin levels different in the otherwise unique subject (premature ovarian failure and autoimmunity). Our study suggests that anti-gonadotropin receptor factors are unlikely to be involved in the majority of patients with premature ovarian failure. However, an anti-FSH receptor factor, possibly an antibody, may be present in some patients, particularly those who have concomitant autoimmune disorders.

Structure-activity relationships of estrogens. Effects of 14-dehydrogenation and axial methyl groups at C-7, C-9 and C-11

Thirty compounds were evaluated in the rat for uterotropic effects, inhibition of gonadotropin release, and competitive displacement of (3H) estradiol-17 beta from uterine cytosolic preparations. 7 alpha-Methylestradiol-17 beta was 150% as active as estradiol-17 beta as an uterotropic agent. Estradiol-17 beta was the most active inhibitor of gonadotropin release. 11 beta-Methylestradiol-17 beta had 124% of the activity of estradiol-17 beta in displacing (3H) estradiol-17 beta from the "estrogen receptor." The 9 alpha-methyl group considerably decreased the potency of estrogens in any of the three assays. The 14-dehydro modification was advantageous only in the estradiol-17 beta 3-methyl ether series. Uterotropic activities and inhibition of gonadotropin release did not parallel. The best compound for inhibiting gonadotropin release, as compared to uterotropic activity, was estrone. The "estrogen receptor" assay data correlated fairly well with uterotropic assay data, but only for compounds having free 3-hydroxyl groups; even so, some exceptions were noted.

Danazol: endocrine consequences in healthy women

We studied the effects of danazol on pituitary and gonadal function in seven normal women who volunteered to take danazol, 400 mg twice daily, for 2 months. We measured circulating levels of sex steroids, gonadotropins, and prolactin on alternate days throughout a control menstrual cycle and during treatment. Danazol inhibited ovulation in all subjects. The amenorrheic state induced by danazol was characterized by normal basal levels of gonadotropins, prolactin, and estrogen. Serum androgen levels were significantly increased as was the urinary excretion of 17-ketosteroids. The LH and FSH responses to gonadotropin-releasing hormone were enhanced during treatment, and there was a normal LH rise following administration of estradiol valerate, indicative of intact positive feedback. These observations fail to support the contention that danazol suppresses pituitary gonadotropin secretion or directly inhibits steroidogenesis. The results suggest that danazol may have a primary site of action at the ovary by suppressing the normal, orderly process of follicular maturation.

Utility of assay of alpha subunit of human chorionic gonadotropin in management of gestational, trophoblastic malignancies

All patients who were treated with chemotherapy for malignant gestational trophoblastic neoplasms at the Southeastern Regional Trophoblastic Disease Center and who experienced remission during the period January 1, 1978, through December 31, 1979, were studied in an attempt to determine if the application of an assay for the alpha subunit of human chorionic gonadotropin (hCG-alpha) could predict those patients who would have recurrences. For each patient, the first three weekly serum samples with undetectable HCG by the hCG beta-subunit radioimmunoassay as well as the two preceding samples with detectable hCG were assayed in a homologous hCG-alpha assay. Results reaffirm previous data that the latter assay is useful only in patients receiving oral contraceptives for suppression of pituitary gonadotropin secretion. No patient who has remained in remission had a mean level of hCG-alpha in the three hCG-negative samples greater than 1 ng/ml. Of those patients who had recurrences of trophoblastic disease, two of three had hCG-alpha levels greater than 1.5 ng/ml. Although these data are preliminary, they suggest that the routine measurement of hCG-alpha in patients successfully treated for trophoblastic disease may aid in identification of a group of patients who require additional or more intensive follow-up and/or additional chemotherapy to prevent later recurrences.

Review: The mechanism of action of danazol, a novel steroid derivative

Danazol is being increasingly used for the treatment of a wide range of disorders, many of which appear to bear little relation to the condition for which the drug was originally marketed--endometriosis. It has been claimed that this drug acts by means of its antigonadotrophic effects on the pituitary; however, a review of the literature reveals that its efficacy in suppressing normal endometrial growth and in causing atrophy of deposits of endometrium cannot be explained solely on this basis. Recent information indicates that, besides acting at the pituitary level, a major mechanism of action may be by a direct inhibitory effect on target tissue. It is sugggested that such a mechanism would more readily account for the diverse effects of this drug in the treatment of many disorders, all of which appear to be associated with an imbalanced sensitivity of target organs to steroid hormones. A greater understanding of its mechanism of action could lead to an even wider application of this novel drug.

Inhibition of testosterone-induced prostate growth in the rat by melatonin-free pineal extract

Administration of the melatonin-free pineal extract to rats concomitantly receiving testosterone propionate caused partial inhibition of the ventral prostate growth induced by testosterone. Administration of the pineal extract to rats likewise caused a statistically significant decrease in the ventral prostate weight under basal conditions. The mechanism of action is discussed.

Blood flow in the reproductive tract of the domestic hen following treatment with a pituitary gonadotropic inhibitor

The effect of pituitary gonadotropic inhibitor--methallibure on the weight and blood flow through reproductive tract was studied in immature hens. It was found that methallibure lowers the weight of the reproductive tract and simultaneously inhibits (about 2--3 times) the blood flow through the ovary and oviductal segments. However, the action of methallibure is of short duration and it is limited to the time of its administration only.

Pituitary gonadotropin inhibition by a highly active analog of luteinizing hormone-releasing hormone

Chronic treatment with highly active analogs of luteinizing hormone (LH)-releasing hormone (LH-RH) induces "paradoxical" antifertility effects. Intact male rats, a reduction in testosterone production is observed after the administration of [D-Ser(But)6]-LH-RH(1-9)ethylamide (burserelin, Hoe 766), 50 ng/day subcutaneously for 4 weeks. In castrated male rats treated with the same dose of analog, plasma LH levels were reduced from days 14 to 28 and plasma follicle-stimulating hormone (FSH) levels were reduced from days 21 to 28 of treatment. Pituitary LH and FSH concentrations were also decreased. The plasma prolactin level was reduced at 14 days of treatment. The hypothalamic LH-RH content remained unchanged and the adrenal corticosterone content was lowered. These findings indicate a direct inhibitory effect of the analog on gonadotropin secretion in the absence of the gonads, and may explain some paradoxical antifertility effects observed with high doses of LH-RH analogs which exceed the physiologic dose range.

Isolation, synthesis, and biological activity of five metabolites of danazol

Metabolites of danazol (17 alpha-pregna-2,4-dien-20-yno[2,3-d]isoxazol-17-ol), an orally effective pituitary gonadotropin inhibitory agent devoid of estrogenic and progestational activites, were isolated from urine of a female subject who had taken danzol orally at a dose of 800 mg/day for 7 days, The metabolites isolated were 17-hydroxy-17alpha-pregn-4-en-20-yn-3-one (11), 17-hydroxy-2alpha-(hydroxymethyl)-17alpha-pregn-4-3n-20-yn-3-one (5), 17-hydroxy-2-(hydroxymethyl)-17alpha-pregna-1,4-dien-20-yn-3-one(7), 6beta,17-dihydroxy-2alpha-(hydroxymethyl)-17alphapregn-4-en-20-yn-3-one(8), and 6beta, 17-dihydroxy-2(hydroxymethyl)-17alphapregna-1,4-dien-20yn-3-one(10). None of these metabolites exhibited pituitary inhibiting activity comparable to danazol.

[Antigonadotropic actions of prolactin. Study of 10 cases of women with hyperprolactinemia]

In order to determine the pituitary or ovarian site of the anti-gonadotrophic action of prolactin (PRL), ten women with hyperprolactinaemia were studied in the following way: 1) Repeated estimations of PRL, gonadotrophins (LH and FSH), plasma estradiol and progesterone during six weeks of treatment with bromocriptine. 2) Verification of the effects of estradiol benzoate on LH and FSH levels before and after normalisation of prolactin. 3) Exploration of the ovarian response to the administration of human menopausal gonadotrophin. Without it being possible to exclude any direct effect of prolactin on the ovary, it may be affirmed that the hormone decreases the sensitivity of the gonadotrophic cells to the positive feedback mechanism exerted by plasma estradiol.

Quantitation of ultrastructural changes in the mouse pineal in response to continuous illumination

Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but nonsignificant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment. These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.

Effect of clomiphene on basal and LRH-induced gonadotropin secretion in postmenopausal women

LRH tests were performed in 11 postmenopausal women before and after the administration of 200 mg of clomiphene citrate daily by mouth for 7 consecutive days. The basal levels and the maximum increments of serum LH (deltaLH) and the area under the response curve from basal level (deltaarea) after LRH administration, significantly (P less than 0.005) decreased after consecutive administration of this compound. Serum FSH levels were significantly (P less than 0.025) decreased but deltaFSH and deltaarea in LRH test were statistically unchanged. These results suggest that clomiphene citrate in postmenopausal women inhibits the pituitary gonadotropin response to exogenous LRH by its estrogenic effects.

Influence of neonatal castration or neonatal anti-gonadotropin treatment on fertility, phallus development, and male sexual behavior in the mouse

Male mice were castrated on the day of birth or were treated with anti-gonadotropin serum (AGS) successively on days 1, 3, and 5 of age. When the adult AGS-treated males were compared with normal rabbit serum (NRS)-treated males with respect to fertility, male sexual behavior, gonadotropin release, body size, and penis size it was found that: (1) fertility of AGS-treated males did not differ from that of NRS-treated males; (2) AGS-treated males showed a significant reduction in penis size, compared with NRS-treated males; (3) both groups showed high levels of male sexual behavior; (4) neither group showed the capacity to support ovulation in ovarian grafts from immature mice. It was also observed that the fertility of female mice treated with AGS on days 1, 3, and 5 of age did not differ from that of control females treated with comparable doses of NRS. Male mice castrated at birth showed a significant reduction in male sexual behavior and penis size compared with males first sham-operated at birth then castrated at 25 days of age. Thus, males castrated at birth were similar to males receiving AGS in infancy, except for sex behavior. The results suggest that the neonatal pituitary in the mouse may not have an important role in the process of sexual differentiation. Previous data for the male rat were compared with those for the mouse.