Induction of ovulation and pregnancy with pulsatile luteinizing hormone releasing factor: dosage and mode of delivery

Physiological and Pharmacological overview of the Gonadotropin Releasing Hormone

Gonadotropin-releasing Hormone (GnRH) is a decapeptide responsible for the control of the reproductive functions. It shows C- and N-terminal aminoacid modifications and two other distinct isoforms have been so far identified. The biological effects of GnRH are mediated by binding to high-affinity G-protein couple receptors (GnRHR), showing characteristic very short C tail. In mammals, including humans, GnRH-producing neurons originate in the embryonic nasal compartment and during early embryogenesis they undergo rapid migration towards the hypothalamus; the increasing knowledge of such mechanisms improved diagnostic and therapeutic approaches to infertility. The pharmacological use of GnRH, or its synthetic peptide and non-peptide agonists or antagonists, provides a valid tool for reproductive disorders and assisted reproduction technology (ART). The presence of GnRHR in several organs and tissues indicates additional functions of the peptide. The identification of a GnRH/GnRHR system in the human endometrium, ovary, and prostate has extended the functions of the peptide to the physiology and tumor transformation of such tissues. Likely, the activity of a GnRH/GnRHR system at the level of the hippocampus, as well as its decreased expression in mice brain aging, raised interest in its possible involvement in neurogenesis and neuronal functions. In conclusion, GnRH/GnRHR appears to be a fascinating biological system that exerts several possibly integrated pleiotropic actions in the complex control of reproductive functions, tumor growth, neurogenesis, and neuroprotection. This review aims to provide an overview of the physiology of GnRH and the pharmacological applications of its synthetic analogs in the management of reproductive and non-reproductive diseases.

The polycystic ovary syndrome: the first 150 years of study

The communities of reproductive medicine and reproductive sciences have been witness to an enormous acceleration of interest in polycystic ovary syndrome (PCO) since the mid-19th century. Although progress has been increasingly palpable, the fundamentals of the etiology and pathophysiology of PCO remain as elusive as ever. Particularly lacking is a requisite understanding of events at the cellular and molecular levels. As we cross the millennial divide, it appears appropriate that an interim progress report be crafted. This treatise is attempting to meet this objective. What follows traces the chronology of the recorded history of PCO in 4 parts.

GnRH in the Human Female Reproductive Axis

Gonadotropin-releasing hormone (GnRH) is recognized as the central regulator of the functions of the pituitary-gonadal axis. The increasing knowledge on the mechanisms controlling the development and the function of GnRH-producing neurons is leading to a better diagnostic and therapeutic approach for hypogonadotropic hypogonadisms and for alterations of the puberty onset. During female life span, the function of the GnRH pulse generator may be affected by a number of inputs from other neuronal systems, offering alternative strategies for diagnostic and therapeutic interventions. Moreover, the identification of a GnRH/GnRH receptor system in both human ovary and endometrium has widened the spectrum of action of the peptide outside its hypothalamic functions. The pharmacological use of GnRH itself or its synthetic analogs (agonists and antagonists) provides a valid tool to either stimulate or block gonadotropin secretion and to modulate the female fertility in several reproductive disorders and in assisted reproduction technology. The use of GnRH agonists in young female patients undergoing chemotherapy is also considered a promising therapeutic approach to counteract iatrogenic ovarian failure.

Dynamiceuticals: The Next Stage in Personalized Medicine

The surge in the interest in personalized medicine necessitates a corresponding rational approach for implementing such individualized therapies. Dynamiceuticals represents a natural extension of the Pharmaceutical and Electroceutical fields, where the precise determination of the dynamical regimes of the pathophysiology will guide to devise therapies that ameliorate the pathology in a well-controlled manner, thus being precisely tailored toward the implementation of individualized medicine. This approach foretells to lessen side-effects and achieve superior efficacy as compared with current trial-and-error or open-loop strategies. But does the current state of knowledge and technology allow this scheme to offer what it claims?

GnRH and GnRH receptors in the pathophysiology of the human female reproductive system

BACKGROUND

Human reproduction depends on an intact hypothalamic-pituitary-gonadal (HPG) axis. Hypothalamic gonadotrophin-releasing hormone (GnRH) has been recognized, since its identification in 1971, as the central regulator of the production and release of the pituitary gonadotrophins that, in turn, regulate the gonadal functions and the production of sex steroids. The characteristic peculiar development, distribution and episodic activity of GnRH-producing neurons have solicited an interdisciplinary interest on the etiopathogenesis of several reproductive diseases. The more recent identification of a GnRH/GnRH receptor (GnRHR) system in both the human endometrium and ovary has widened the spectrum of action of the peptide and of its analogues beyond its hypothalamic function.

METHODS

An analysis of research and review articles published in international journals until June 2015 has been carried out to comprehensively summarize both the well established and the most recent knowledge on the physiopathology of the GnRH system in the central and peripheral control of female reproductive functions and diseases.

RESULTS

This review focuses on the role of GnRH neurons in the control of the reproductive axis. New knowledge is accumulating on the genetic programme that drives GnRH neuron development to ameliorate the diagnosis and treatment of GnRH deficiency and consequent delayed or absent puberty. Moreover, a better understanding of the mechanisms controlling the episodic release of GnRH during the onset of puberty and the ovulatory cycle has enabled the pharmacological use of GnRH itself or its synthetic analogues (agonists and antagonists) to either stimulate or to block the gonadotrophin secretion and modulate the functions of the reproductive axis in several reproductive diseases and in assisted reproduction technology. Several inputs from other neuronal populations, as well as metabolic, somatic and age-related signals, may greatly affect the functions of the GnRH pulse generator during the female lifespan; their modulation may offer new possible strategies for diagnostic and therapeutic interventions. A GnRH/GnRHR system is also expressed in female reproductive tissues (e.g. endometrium and ovary), both in normal and pathological conditions. The expression of this system in the human endometrium and ovary supports its physiological regulatory role in the processes of trophoblast invasion of the maternal endometrium and embryo implantation as well as of follicular development and corpus luteum functions. The GnRH/GnRHR system that is expressed in diseased tissues of the female reproductive tract (both benign and malignant) is at present considered an effective molecular target for the development of novel therapeutic approaches for these pathologies. GnRH agonists are also considered as a promising therapeutic approach to counteract ovarian failure in young female patients undergoing chemotherapy.

CONCLUSIONS

Increasing knowledge about the regulation of GnRH pulsatile release, as well as the therapeutic use of its analogues, offers interesting new perspectives in the diagnosis, treatment and outcome of female reproductive disorders, including tumoral and iatrogenic diseases.

Ovarian hypertension: polycystic ovary syndrome

Hypertension is a significant contributor to the risk for cardiovascular disease. The increased prevalence of hypertension in women with polycystic ovary syndrome (PCOS) may contribute to the increased risk of cardiovascular disease in these women. Whether hypertension is associated with PCOS independent of obesity remains controversial. Nevertheless, detection and subsequent treatment of hypertension in this population should decrease the adverse sequelae from hypertensive cardiovascular disease. Treatment of risk factors inherent to PCOS, such as hyperandrogenism, insulin resistance, and obesity, may minimize the risk not only for the development of hypertension but also for incident cardiovascular disease independent of hypertension.

A Model Based on Receptor Desensitization for Cyclic AMP Signaling in Dictyostelium Cells

We analyze a model based on receptor modification for the cAMP signaling system that controls aggregation of the slime mold Dictyostelium discoideum after starvation. The model takes into account both the desensitization of the cAMP receptor by reversible phosphorylation and the activation of adenylate cyclase that follows binding of extracellular cAMP to the unmodified receptor. The dynamics of the signaling system is studied in terms of three variables, namely, intracellular and extracellular cAMP, and the fraction of receptor in active state. Using parameter values collected from experimental studies on cAMP signaling and receptor phosphorylation, we show that the model accounts qualitatively and, in a large measure, quantitatively for the various modes of dynamic behavior observed in the experiments: (a) autonomous oscillations of cAMP, (b) relay of suprathreshold cAMP pulses, i.e., excitability, characterized by both an absolute and a relative refractory period, and (c) adaptation to constant cAMP stimuli. A two-variable version of the model is used to demonstrate the link between excitability and oscillations by phase plane analysis. The response of the model to repetitive stimulation allows comprehension, in terms of receptor desensitization, of the role of periodic signaling in Dictyostelium and, more generally, the function of pulsatile patterns of hormone secretion.

Time-patterned drug administration: insights from a modeling approach

The physiological effects of a drug depend not only on its molecular structure but also on the time-pattern of its administration. One of the main reasons for the importance of temporal patterns in drug action is biological rhythms--particularly those of circadian period. These rhythms affect most physiological functions as well as drug metabolism, clearance, and dynamic processes that may alter drug availability and target cell responsiveness with reference to biological time. We present an overview of the importance of time-patterned signals in physiology focused on the insights provided by a modeling approach. We first discuss examples of pulsatile intercellular communication by hormones such as gonadotropin-releasing hormone, and by cyclic adenosine monophosphate (cAMP) signals in Dictyostelium amoebae. Models based on reversible receptor desensitization account in both cases for the existence of optimal patterns of pulsatile signaling. Turning to circadian rhythms, we examine how models can be used to account for the response of 24h patterns to external stimuli such as light pulses or gene expression, and to predict how to restore the physiological characteristics of altered rhythms. Time-patterned treatments of cancer involve two distinct lines of research. The first, currently evaluated in clinical trials, relies on circadian chronomodulation of anticancer drugs, while the second, mostly based on theoretical studies, involves a resonance phenomenon with the cell-cycle length. We discuss the implications of modeling studies to improve the temporal patterning of drug administration.

Chronobiology and chronotherapy in medicine

There is a fascinating and exceedingly important area of medicine that most of us have not been exposed to at any level of our medical training. This relatively new area is termed chronobiology; that is, how time-related events shape our daily biologic responses and apply to any aspect of medicine with regard to altering pathophysiology and treatment response. For example, normally occurring circadian (daily cycles, approximately 24 hours) events, such as nadirs in epinephrine and cortisol levels that occur in the body around 10 PM to 4 AM and elevated histamine and other mediator levels that occur between midnight and 4 AM, play a major role in the worsening of asthma during the night. In fact, this nocturnal exacerbation occurs in the majority of asthmatic patients. Because all biologic functions, including those of cells, organs, and the entire body, have circadian, ultradian (less than 22 hours), or infradian (greater than 26 hours) rhythms, understanding the pathophysiology and treatment of disease needs to be viewed with these changes in mind. Biologic rhythms are ingrained, and although they can be changed over time by changing the wake-sleep cycle, these alterations occur over days. However, sleep itself can adversely affect the pathophysiology of disease. The non-light/dark influence of biologic rhythms was first described in 1729 by the French astronomer Jean-Jacques de Mairan. Previously, it was presumed that the small red flowers of the plant Kalanchoe bloss feldiuna opened in the day because of the sunlight and closed at night because of the darkness. When de Mairan placed the plant in total darkness, the opening and closing of the flowers still occurred on its intrinsic circadian basis. It is intriguing to think about how the time of day governs the pathophysiology of disease. On awakening in the morning, heart rate and blood pressure briskly increase, as do platelet aggregability and other clotting factors. This can be linked to the acrophase (peak event) of heart attacks. During the afternoon we hit our best mental and physical performance, which explains why most of us state that "I am not a morning person." Even the tolerance for alcohol varies over the 24-hour cycle, with best tolerance around 5 pm (i.e. "Doctor, I only have a couple of highballs before dinner"). Thus, all biologic functions, from those of the cell, the tissue, the organs, and the entire body, run on a cycle of altering activity and function.(ABSTRACT TRUNCATED AT 400 WORDS)

Induction of testicular growth and spermatogenesis by pulsatile, intravenous administration of gonadotrophin-releasing hormone in patients with hypogonadotrophic hypogonadism

OBJECTIVE

To induce testicular growth including spermatogenesis, 38 patients with hypogonadotrophic hypogonadism were treated with long-term pulsatile GnRH administration.

PATIENTS

The group of patients comprised 17 individuals with idiopathic hypogonadotrophic hypogonadism, 11 with Kallmann's syndrome, four with multiple pituitary hormone deficiencies and six with a secondary hypogonadotrophic hypogonadism due to surgical removal of a brain tumour. Thirteen patients (seven with idiopathic hypogonadotrophic hypogonadism and six with Kallmann's syndrome) had undescended testes, of whom six had undergone surgery on both testes and four on one testis. Sixteen of the 17 had previously received androgen therapy and six others had received gonadotrophin treatment, of whom three had long-term treatment to induce testicular development, without success.

TREATMENT

GnRH was administered intravenously in a dose of 2-20 micrograms per pulse every 90 minutes. After GnRH discontinuation, hCG treatment was instituted, 1500-3000 IU (i.m.) twice weekly.

RESULTS

During treatment plasma levels of LH, FSH and testosterone increased. In 35 out of the 38 patients plasma testosterone levels increased into the normal adult range. In all patients testicular volume increased. Mean pretreatment testicular volume per patient group ranged from 2.4 to 4.8 ml and increased to 11.5-18.1 ml by the end of treatment. There was a significant difference in the achieved testicular volumes between the patients with Kallmann's syndrome and the brain tumour patients. GnRH treatment mean lasted between 46 and 75 weeks in the different groups. On hCG therapy, testicular development was either maintained or improved. Semen analysis revealed the presence of spermatogenesis in 31 out of the 38 patients (26 patients already on GnRH, and in another five patients on hCG therapy). All three patients pretreated with gonadotrophins as well as three patients with bilateral testicular surgery developed a detectable sperm count. In 19 adolescent patients with growth potential, an adequate height velocity was observed during GnRH treatment.

CONCLUSIONS

GnRH is a feasible way to induce testicular growth as well as spermatogenesis in hypogonadotrophic male patients, even in patients in whom gonadotrophin treatment has failed. After GnRH treatment, hCG alone can maintain or even improve testicular development, including spermatogenesis. GnRH treatment may also induce a physiological growth spurt in hypogonadotrophic adolescents.

Endocrinology of gonadotropin-releasing hormone induced cycles in hypothalamic amenorrhea: the role of the pulse dose

OBJECTIVE

To find the treatment regimen giving a maximum chance of ovulation and a minimal chance of multiple follicular development in pulsatile gonadotropin-releasing hormone (GnRH) therapy in patients with hypothalamic amenorrhea.

DESIGN

We propectively studied the endocrinology of cycles induced with 5, 10, and 20 micrograms GnRH pulse doses, randomly assigned per patient, comparing this with the endocrinology of spontaneous menstrual cycles.

SETTING

All patients were treated at the Academic Hospital of the Vrije Universiteit, Division of Reproductive Endocrinology and Fertility.

PATIENTS

Fifteen patients with hypothalamic amenorrhea were treated for one to three cycles; 14 normally cycling volunteers were studied for one cycle.

MAIN OUTCOME MEASURE

Number of ovulations per pulse dose; luteinizing hormone, follicle-stimulating hormone, total urinary estrogens (Es), and pregnanediol were measured per cycle day and per stimulation day.

RESULTS

The endocrinology of all ovulatory cycles remained within the normal range. First treatment cycles showed significantly higher ovulation rates compared with subsequent cycles. Significantly more anovulation was observed in cycles with 5-micrograms pulse doses. Luteal Es were significantly higher in induction cycles compared with controls.

CONCLUSIONS

The optimum treatment regimen should be to start induction with 5 micrograms/pulse in the first cycle and to raise the dose to 10 micrograms/pulse in subsequent cycles, regardless of the outcome of the first cycle. After ovulation, the pulse interval should be changed to 240 minutes.

Efficacy and safety of intravenous pulsatile gonadotropin-releasing hormone: Lutrepulse for injection

A multicenter trial was undertaken to assess the ability of pulsatile gonadotropin-releasing hormone to restore physiologic ovulatory function in women with diminished or absent pulsatile gonadotropin-releasing hormone secretion. In 109 women with primary and secondary hypothalamic amenorrhea, pulsatile gonadotropin-releasing hormone (Lutrepulse [gonadorelin acetate] for Injection) was extremely effective, resulting in ovulation in 91% and 96% of patients, respectively. Overall complications of intravenous line placement ranged from 0% to 11% (mean = 7%). A 12% incidence of multiple pregnancy was noted, and a single case of ovarian hyperstimulation was reported in a woman who also received clomiphene citrate. Pulsatile gonadotropin-releasing hormone treatment appears to be of at least comparable efficacy to human menopausal gonadotropins, with the added benefit of reduced overall risks for the patient with hypothalamic amenorrhea.

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.

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.

Pituitary function in isolated gonadotrophin deficiency

Hypothalamic-pituitary function was assessed in 24 individuals with isolated gonadotrophin deficiency (IGD). Thirteen had normal olfaction (Group I) while 11 (Group II) had anosmia (Kallmann's syndrome). In response to a 10 micrograms intravenous (i.v.) bolus of GnRH, the minimal dose required to evoke a consistent gonadotrophin response in normal subjects, the patients responded with significant LH and FSH increases over baseline (P less than 0.01). In Group II patients, large doses (150 micrograms) of GnRH, which elicit maximal release of gonadotrophin in normal subjects did not increase gonadotrophin release beyond that produced by a 10 micrograms bolus. In response to two 10 micrograms GnRH doses, at times 0 and 120 min, the IGD patients responded with similar LH increases to both boluses (both P less than 0.01 compared to baseline). The maximal PRL responses to arginine infusion and to TRH in the male patients were similar to those of normal males. However, in the IGD females, the PRL response to TRH was less than in normal females. The TSH responses to TRH in IGD males and females were similar to each other and similar to normal. The IGD male GH response to arginine infusion was comparable to that in normal males. We conclude that (1) IGD patients appear to retain minimal endogenous GnRH secretion so that the IGD pituitary responds to a minimal dose of GnRH without priming; (2) IGD is a heterogeneous syndrome in which affected individuals with and without normal olfaction represent parts of the spectrum of the same disease; and (3) except for the PRL response in females, the PRL, TSH and GH responses demonstrate that the IGD pituitaries are largely intact.

Ovulation induction with intravenous gonadotropin-releasing hormone

The efficacy of ovulation induction with the use of pulsatile gonadotropin-releasing hormone (GnRH) therapy was examined in 21 infertile women. Seventeen had hypothalamic amenorrhea (HA) and 4 polycystic ovary syndrome (PCO). All patients were treated as outpatients. GnRH was infused in a pulsatile mode by means of portable auto-infusion pumps connected to an indwelling intravenous catheter inserted into a forearm vein. The doses varied from 1.8 to 5 micrograms/pulse with a frequency of 90 minutes. Ovulation occurred in 52 out of 64 cycles (81.2%). Ten (47.6%) of the 21 patients became pregnant. Seven patients had normal term deliveries and 3 aborted spontaneously. With regard to the 17 patients with HA, ovulation occurred in 93.7% of treatment cycles and 6 women became pregnant. In the case of the PCO patients, ovulation was achieved in 6 out of 15 cycles (40%) and 2 women became pregnant. There was no overstimulation or any other serious complication. In conclusion, therapy with GnRH provides an elevated probability of therapeutic success, especially in HA.

Induction of ovulation with subcutaneous pulsatile gonadotropin-releasing hormone: correlation with body weight and other parameters

We treated 21 anovulatory infertile patients with subcutaneous pulsatile gonadotropin-releasing hormone (GnRH) administered via a syringe pump. Response to treatment was assessed by urinary estrogen excretion and ultrasound measurement of follicular growth. Ten patients ovulated and 8 subsequently conceived, for a total of 10 pregnancies. Human chorionic gonadotropin (hCG) was not administered routinely, but two patients required hCG to induce follicular rupture. The majority of the patients who conceived had a body mass index (BMI) of less than 21 and a luteinizing hormone (LH)/follicle-stimulating hormone ratio of less than 1. Conversely, those patients with either elevated BMI or LH or both generally failed to respond satisfactorily to this treatment. It is suggested that pulsatile GnRH is most likely to succeed in inducing ovulation if the BMI is less than 21 and the LH is normal, but is unlikely to be successful if there is both an elevated LH and a BMI of greater than 25. Between these two extremes, the response is variable and a therapeutic trial may be appropriate.

Frequency specificity in intercellular communication. Influence of patterns of periodic signaling on target cell responsiveness

Cells often communicate by means of periodic signals, as exemplified by a large number of hormones and by the aggregation of Dictyostelium discoideum amebas in response to periodic pulses of cyclic AMP. Periodic signaling allows bypassing the phenomenon of desensitization brought about by constant stimuli. To gain further insight into the efficiency of pulsatile signaling, we analyze the effect of periodic stimulation on the dynamic behavior of a receptor system capable of desensitization toward its ligand. We first show that the receptor system adapts to square-wave stimuli, i.e., the response eventually reaches a steady, periodic pattern after a transient phase. By analyzing the dependence of the response on the characteristics of the square-wave stimulation, we show that there exist a waveform and a period of that signal that result in maximum responsiveness of the target system. Similar results are obtained when the signal takes the more realistic form of a periodically repeated stimulation followed by exponential decay of the ligand. The results are discussed with respect to the role of pulsatile secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus and of periodic signaling by cyclic AMP pulses in Dictyostelium. The analysis accounts for the existence, in both cases, of an optimal frequency and waveform of the periodic stimulus that correspond to maximum target cell responsiveness.

Pituitary response during pulsatile luteinizing hormone-releasing hormone ovulation--induction in patients with clomiphene citrate-resistant polycystic ovary-like disease

The pituitary response to pulsatile luteinizing hormone-releasing hormone (LRH) was studied in 6 women with clomiphene-resistant polycystic ovary-like disease (PCOD). PCOD was defined as oligomenorrhea, elevated luteinizing hormone (LH), normal follicle-stimulating hormone (FSH), and, in general, elevated androgens. LRH was administered in a pulsatile way, chronically, with a pulse dose of 20 micrograms and a pulse interval of 60, 90 and 120 minutes. Blood was drawn every 10 minutes for 6 hours, at the start of therapy (pulse study 1) and 9-15 days after the start of therapy (pulse study 2). Five patients ovulated within 10 days of therapy, which meant that pulse study 2 was performed during the luteal phase. One patient remained anovulatory. The follicular and luteal response during LRH therapy was comparable to that of normal cycles, although the pituitary response was enhanced in PCOD at the start of therapy, which might be related to the state in which the ovary finds itself with respect to follicular development. Desensitization for LH to LRH occurred only incidentally during pulse study 1. Desensitization for FSH to LRH already developed during pulse study 1 and continued to existed during therapy. The 60, 90 and 120 minute LRH pulse interval regimes resulted in LH nadir intervals with wide ranges, although the medians were 60, 90 and 120 minutes respectively.

Comparison of pulsatile subcutaneous gonadotropin-releasing hormone and exogenous gonadotropins in the treatment of men with isolated hypogonadotropic hypogonadism

Eight men with isolated hypogonadotropic hypogonadism were treated with pulsatile gonadotropin-releasing hormone (GnRH) after maximal testicular growth and function had already been achieved with human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG). Only four subjects could normalize plasma testosterone (T) levels (group A). After 18 months of GnRH therapy, testicular size of group A increased by 53% (P less than 0.01) over that previously attained with exogenous gonadotropins. However, despite further testicular growth, two men who were previously azoospermic on hCG/hMG remained so on GnRH. In the other two patients, total sperm count increased minimally. Thus, pulsatile gonadotropin levels achieved with GnRH are more effective in stimulating testicular growth, but not necessarily sperm output, than are stable gonadotropin concentrations obtained with hCG/hMG.

The theory and practice of ovulation induction with gonadotropin-releasing hormone

Gonadotropin-releasing hormone therapy has undergone sufficient basic and clinical investigation as a tool for ovulation induction that it should now be considered a safe and effective infertility therapy for office practice. Nevertheless, there remains sufficient mystique about patient selection, optimal dosage and route of delivery, and apprehension on the part of both physicians and patients about cost and inconvenience of medication pumps that gonadotropin-releasing hormone therapy has not enjoyed the widespread acceptance it deserves. This article presents straightforward guidelines for therapy that are based on a detailed review of current literature, together with new information about evolving pump technologic characteristics, that should offer reassurance to the practitioner considering use of gonadotropin-releasing hormone therapy in her/his practice.

The impact of dosage on ovulation induction by pulsatile gonadotropin-releasing hormone (Gn-RH) in hypothalamic amenorrhea

Ten patients with hypothalamic amenorrhea (HA) were treated to induce ovulation with i.v. pulsatile Gn-RH. Twentysix cycles were administered with doses ranging from 2.5 (A; no. = 10) to 5 (B; no. = 13) to 10-12.5 micrograms/90 min (C; no. = 3). Ovulation rate was 80% in A, 92.3% in B and 100% in C and pregnancy rate 25% in A and 41.6% in B. Furthermore, both the onset of ovarian response and follicular growth were found to be more suitable in groups B and C with respect to group A. Estradiol pattern as well as mid-luteal progesterone plasma levels were superimposable in the different groups. It is concluded that all doses used are effective in inducing ovulation in HA patients. However, small pulsatile doses (2.5 micrograms/90 min) might constitute a critical threshold for adequate ovarian response.

Evidence for gonadal desensitization after pulsatile therapy in women with amenorrhoea?

Sixteen women with primary and secondary amenorrhoea were treated with pulsatile GnRH administered subcutaneously. Ovulation was successfully induced in 6/8 women with hypogonadotrophic hypogonadism; and in 2/2 women with idiopathic hyperprolactinaemia; but in only 3/6 women with amenorrhoea associated with an elevated LH:FSH ratio. Using serial blood sampling, we were unable to demonstrate the establishment of a physiological pattern of gonadotrophin secretion in the presence of an apparently normal menstrual cycle. Nor did we observe a consistent relationship between injection of GnRH and the resultant gonadotrophin response. A reduction or total cessation of both pituitary and gonadal sensitivity to GnRH was observed in four women. Possible reasons for these findings are discussed.

Exogenous GnRH overrides the endogenous annual reproductive rhythm in green iguanas, Iguana iguana

Female green iguanas, Iguana iguana, were caught in Belize, Central America (17 degrees N), in December, at the onset of seasonal gonadal activity. The animals were immediately transferred to San Diego (32 degrees N). Ovarian follicular development continued, with peak plasma hormone levels measured in January and February; 200 pg/ml for progesterone (P) and 800 pg/ml for total estrogens (Et = estradiol [E2] + estrone [E1]). E2 was the predominant estrogen throughout the cycle. Follicular atrophy was indicated in April with circulating progesterone and estrogen levels decreasing to baseline (refractory phase) levels (P = 20 pg/ml; Et = 50 pg/ml). Approximately midway through the refractory phase of their annual reproductive cycle (late May), either the D-Arg6 analog of Chicken II or mammalian GnRH was administered via intraperitoneal osmotic pumps for 14 days to nine females. The analog of chicken II induced a fivefold increase in total circulating estrogens within 3-4 days after implantation. Both continuous and pulsatile delivery of the chicken II analog produced a similar pattern of steroidogenic response. A radical sham control animal showed no increase in steroidogenesis. Mammalian GnRH produced a pattern of similar duration, although the magnitude of the steroidogenic response was only half that produced by the chicken II analog. Estrogen titers approached baseline levels in all treatment groups two days after treatment ceased. Progesterone levels increased in all treatment groups during the delivery of exogenous GnRH, although the increases were not consistent. Untreated male cagemates housed with treated females exhibited increased territoriality, courtship behavior, and mating, which began on day 4 or 5 of the treatment period. The control female was not courted by its male cagemate.

Treatment of hyperprolactinemic amenorrhea with pulsatile gonadotropin-releasing hormone therapy

Pulsatile GnRH therapy has been shown effective in the treatment of infertility associated with hyperprolactinemia by direct action on the pituitary. Gonadotropin secretion was restored in the setting of moderate hyperprolactinemia. GnRH should be considered as a potential alternative to BCPT therapy in this setting.

Effect of injection site on the pharmacokinetics and pharmacodynamics of subcutaneously administered luteinizing hormone releasing hormone

Serum concentrations of LHRH and the subsequent LH responses were compared following s.c. injections of 20 micrograms LHRH into the upper arm and the lower abdominal wall, in 9 hypogonadal women responsive to pulsatile LHRH therapy. Tests were carried out at the two sites in random order. Peak LHRH concentrations were reached by 5 min after upper arm and by 20 min after lower abdominal wall injections, the maximum concentrations being significantly greater following injections into the former. There was no increase in LH until 10 min and then maximum concentrations were reached at 30 min following injection into both sites. There was no significant correlation between the LHRH increments and the LH response but there was a negative correlation between the Ponderal Index of the patients and the LHRH increments following injections into the lower abdominal wall only. There was no significant overall difference between the LH increments related to the site of injection, but the order of injections affected the responses. When upper arm injections were given first the LH responses were significantly greater, but when lower abdominal wall was injected first the subsequent responses to upper arm injections were impaired. A possible reason for this is that the absorption from the lower abdominal wall was delayed so prolonging the exposure of the pituitary gonadotrophs to LHRH, resulting in pituitary desensitization at the time of the second test.

The hormonal response of patients with polycystic ovarian disease to subcutaneous low frequency pulsatile administration of luteinizing hormone-releasing hormone

Four patients with oligoamenorrhea manifesting hormonal and clinical features of polycystic ovarian disease (PCOD) were selected for treatment. All patients had high luteinizing hormone (LH) levels and a basal LH/follicle-stimulating hormone (FSH) ratio of greater than 3. Three of them had high androgen levels with normal adrenal cortical function. The four patients were treated for 12 cycles by pulsatile LH-releasing hormone (LH-RH) subcutaneously. Frequency of pulses varied between once in every 120 to once in every 400 minutes in consecutive cycles, in an attempt to reverse LH/FSH ratio. The dose of LH-RH varied between 20 and 40 micrograms/pulse. Treatment was monitored hormonally by the determinations of LH, FSH, 17 beta-estradiol, prolactin, progesterone, testosterone (T) (total and free), androstenedione (delta 4A), dehydroepiandrosterone sulfate (DHEA-S), and sex hormone-binding globulin (SHBG) every 2 days. The most striking change was the lowering of the LH/FSH ratio to the normal range, due to LH decrease and FSH increase with a pulse frequency of 180 to 240 minutes. DHEA-S levels reversed to normal in two patients and were reduced in one patient. T and delta 4A levels returned to normal with elevation to normal of SHBG. These hormonal improvements did not result in ovulation as expected (2 of 12 cycles). It may be assumed that either subcutaneous administration is inadequate in PCOD patients or that the frequency of pulses needed to correct the hormonal disturbances in PCOD patients differs from that needed for ovum maturation and ovulation.

Derangement of pituitary gonadotropin release with different GnRH pulsatile patterns in chronic intravenous or subcutaneous delivery

The efficacy of iv and sc chronic GnRH administration with different pulsatile patterns (15 micrograms every 90 min and 7.8 micrograms every 90 min with minor intermediate pulses of 2.3 micrograms every 22.2 min) by means of portable pumps were evaluated in a patient with primary hypothalamic amenorrhea. Observations of the amplitude and duration of the induced serum gonadotropin concentrations, of follicular growth (via ultrasound), and of ovarian steroids were made. Iv delivery of GnRH, 15 micrograms every 90 min, induced a normal menstrual cycle. Dividing this dose, as described above, giving it iv and sc, resulted in inappropriate gonadotropin secretion (overstimulation and desensitization, respectively) and arrest of follicular development. Sc delivery of 15 micrograms GnRH every 90 min resulted in an insufficient LH stimulation.

Induction of ovulation with pulsatile subcutaneous administration of human menopausal gonadotropin in anovulatory infertile women

Pulsatile administration of human menopausal gonadotropin (hMG) via the subcutaneous route was evaluated in 15 patients with various ovulatory disorders. Administration of hMG was started at a dose of 4.6875 IU (75 IU/day) or 9.375 IU (150 IU/day) per pulse every 90 minutes. Ovulation was observed in 26 (92.9%) of 28 treatment cycles, and two singleton pregnancies were confirmed. Ovarian hyperstimulation was observed in 1 to 26 ovulatory cycles; however, no other side effects were observed during treatment. A regimen of 75 IU/day resulted in a significant increase (P less than 0.0001) of the total dose and prolongation of the treatment period for induction of ovulation, as compared with that of 150 IU/day. Shortened luteal phases occurred in ovulatory cycles induced by pulsatile subcutaneous treatment. Human chorionic gonadotropin administration given every other day until the midluteal phase significantly prolonged the duration of the luteal phase (P less than 0.05). This treatment in patients with the polycystic ovary syndrome was followed by a normalization of luteinizing hormone/follicle-stimulating hormone ratio and resulted in a successful induction of ovulation in 8 to 10 cycles. The present data demonstrated that pulsatile subcutaneous administration of hMG was effective in inducing follicular maturation and ovulation in patients with various types of anovulatory infertility.

Pulsatile luteinizing hormone releasing hormone treatment for induction of ovulation. Radioimmunoassay of plasma LHRH and comparative study of subcutaneous versus intravenous routes of administration

To investigate the efficacy of the different routes of luteinizing hormone releasing hormone (LHRH) administration upon pituitary responsiveness, we compared plasma LHRH concentrations and pituitary LH responses in four patients with hypothalamic amenorrhea treated with pulsatile LHRH. A portable computerized infusion pump delivered sc or iv LHRH pulses of 5, 10 or 20 micrograms every 90 min. Comparison of the two modes of LHRH delivery was performed using radioimmunoassay of exogenous LHRH and studying its pharmacokinetics for a 3 pulses period. With 10 micrograms of LHRH given iv, plasma LHRH levels increased between 700 and 1000 pg/ml within 3 min and returned to basal levels in 30 min. When given sc (10 micrograms), plasma LHRH levels peaked between 80 and 100 pg/ml in 15 min and returned to basal levels 60 min later. In one patient treated with 5 micrograms per pulse iv or sc, plasma LHRH increased to 380 and 60 pg/ml respectively. In all patients, computerized analysis of LH pulses was performed during sc and iv LHRH administration. LH pulsatile release displayed a similar rhythm period with both routes. However, for the same dose of LHRH (10 micrograms), the adjusted mean of LH plasma levels was lower with the sc route. In conclusions, the pharmacokinetics of LHRH administered sc or iv displayed a similar pattern but, with equivalent doses, higher plasma LHRH levels are attained with the iv route. Concomitantly, the mean LH levels were also greater after iv administration. Ovulation can be successfully induced by both pulsatile iv and sc LHRH therapy. However, with the sc route, a higher dose of LHRH should be used to prevent a delay of ovulation or a luteal deficiency.

Episodic luteinizing hormone release in hyperprolactinemic women

Episodic luteinizing hormone (LH) secretion was studied in 16 hyperprolactinemic women (microprolactinoma, 12; idiopathic, 4) with amenorrhea of 1.4 to 7 years' duration. Blood samples obtained through an indwelling venous catheter at 20-minute intervals over 5 hours were assayed for LH, follicle-stimulating hormone (FSH), prolactin (PRL), and estrogen (E) (selected samples). LH pulse patterns were divided arbitrarily into high-amplitude release (LH pulse greater than 10 mIU/ml) (n = 7), low-amplitude release (LH pulse less than 10 mIU/ml (n = 6), and no release (n = 3). Mean pulse frequencies in women with high-amplitude and low-amplitude release were 2.4 +/- 0.3 (mean +/- standard error) and 1.3 +/- 0.2 pulses/5 hours and differed significantly (P greater than 0.02), whereas mean percentages of secretory increment were 155% and 62%, respectively. Mean LH concentrations in the high-amplitude (18.0 +/- 0.8 mIU/ml), low-amplitude (13.2 +/- 0.6 mIU/ml), and no-pulse groups (7.5 +/- 0.2 mIU/ml) differed significantly (P greater than 0.02). Despite the different pulse patterns, mean serum FSH, PRL, and total E concentrations were similar. The lack of episodic LH release and/or low infrequent LH release could account for the absence of cyclic hypothalamic pituitary ovarian function, although other mechanism(s) may be operative in women with augmented LH secretory pulses.

Alternative indications for pulsatile gonadotropin-releasing hormone therapy in infertile women

Three groups of women with different types of ovulatory dysfunction who had failed to conceive on conventional therapy were treated with pulsatile gonadotropin-releasing hormone (GnRH). Group A consisted of nine patients with luteal phase defect; group B included four patients with apparently normal menstrual cycles but disordered folliculogenesis seen by serial ultrasound examinations; and group C consisted of eight patients who exhibited anovulation or irregular ovulation. GnRH was administered subcutaneously or intravenously in dosages varying from 5 micrograms to 20 micrograms, with pulse frequency of 2 to 3 hours in 53 cycles. Forty-one cycles were ovulatory. Four pregnancies resulted, one ending in miscarriage at 12 weeks' gestation. Our results indicate that GnRH may be used as an alternative to the prevalent therapeutic methods for ovulatory dysfunction. Only those women who had anovulation and abnormal basal levels of serum luteinizing hormone were resistant to GnRH therapy.

Serum luteinizing hormone-releasing hormone (LH-RH) and gonadotropic hormones in men after a bolus dose of LH-RH: comparison of different doses and routes of administration

Serum levels of luteinizing hormone-releasing hormone (LH-RH), LH, and follicle-stimulating hormone (FSH) were measured for 60 minutes after 5- and 20-micrograms bolus doses of LH-RH given either intravenously or subcutaneously to 20 healthy men, for the study of LH-RH pharmacokinetics and the corresponding pituitary gonadotropin release. Intravenous (5- and 20-micrograms) LH-RH administration revealed much sharper LH-RH pulses, with significantly higher levels between 1 and 5 minutes (P less than 0.001) but lower levels between 30 and 60 minutes (P less than 0.05), compared with the subcutaneous route. No statistically significant differences were observed in the magnitude and time occurrence of maximum LH release or in the area under the LH response curves between intravenous and subcutaneous LH-RH administration, either in the 5-micrograms or in the 20-micrograms group. FSH responses were small and insignificant in all the performed tests. The intravenous route of administration seems preferential in therapeutic regimens that use pulsatile exogenous LH-RH, because the conditions of intermittent pituitary stimulation are more adequately fulfilled and the risk of dose accumulation is reduced. Furthermore, LH-RH doses of 5 micrograms are capable of producing adequate pituitary LH release, whereas increases in the pulse dose up to 20 micrograms seem to have no additional effects.

The induction of ovulation using pulsatile luteinizing hormone releasing hormone in clinical practice

Until recently induction of ovulation in patients resistant to clomiphene has required gonadotrophin therapy. This has entailed intensive biochemical monitoring to ascertain the correct dosage and to avoid ovarian hyperstimulation. Described here is a simple, safe effective method of ovulation induction, using pulsed luteinizing hormone releasing hormone and requiring only minimal, readily available monitoring methods.