Spontaneous episodic release of adenohypophyseal hormones in hypothalamic amenorrhea

Neuroendocrine disturbances in women with functional hypothalamic amenorrhea: an update and future directions

Functional hypothalamic amenorrhea (FHA) is one of the most common causes of both primary and secondary amenorrhea in women of reproductive age. It is characterized by chronic anovulation and the absence of menses that appear as a result of stressors such as eating disorders, excessive exercise, or psychological distress. FHA is presumed to be a functional disruption in the pulsatile secretion of hypothalamic gonadotropin-releasing hormone, which in turn impairs the release of gonadotropin. Hypoestrogenism is observed due to the absence of ovarian follicle recruitment. Numerous neurotransmitters have been identified which play an important role in the regulation of the hypothalamic-pituitary-ovarian axis and of which the impairment would contribute to developing FHA. In this review we summarize the most recent advances in the identification of contributing neuroendocrine disturbances and relevant contributors to the development of FHA.

Low-Dose Estrogens as Neuroendocrine Modulators in Functional Hypothalamic Amenorrhea (FHA): The Putative Triggering of the Positive Feedback Mechanism(s)

Functional hypothalamic amenorrhea (FHA) is a non-organic reversible chronic endocrine disorder characterized by an impaired pulsatile secretion of the gonadotropin-releasing hormone (GnRH) from the hypothalamus. This impaired secretion, triggered by psychosocial and metabolic stressors, leads to an abnormal pituitary production of gonadotropins. As LH and FSH release is defective, the ovarian function is steadily reduced, inducing a systemic hypoestrogenic condition characterized by amenorrhea, vaginal atrophy, mood changes and increased risk of osteoporosis and cardiovascular disease. Diagnosis of FHA is made excluding other possible causes for secondary amenorrhea, and it is based upon the findings of low serum gonadotropins and estradiol (E2) with evidence of precipitating factors (excessive exercise, low weight, stress). Treatments of women with FHA include weight gain through an appropriate diet and physical activity reduction, psychological support, and integrative approach up to estrogen replacement therapy. If no spontaneous ovarian function is restored, assisted reproductive technologies may be used when pregnancy is desired. Because subjects with FHA are hypoestrogenic, the use of low-dose estrogens has been proposed as a putative treatment to positively modulate the spontaneous restart of gonadotropin secretion, counteracting the blockade of the reproductive axis triggered by stress acting through the neuroendocrine pathways at the basis of positive feedback of estrogens. The mechanism through which low-dose estrogens acts is still unknown, but kisspeptin-secreting neurons may be involved.

Administration of Very Low Doses of Estradiol Modulates the LH Response to a GnRH Bolus and the LH and Cortisol Responses to Naloxone Infusion in Patients with Functional Hypothalamic Amenorrhea (FHA): A Pilot Study

Background: Functional Hypothalamic Amenorrhea (FHA) is a stress-induced blockade of the reproductive axis. Such impairment is mainly due to altered control of GnRH-induced gonadotropin secretion as well as alterations of other endocrine functions. Methods: Seventeen patients with FHA participated in the study. Basal hormonal profiles and GnRH and Naloxone tests for LH (Luteinizing Hormone) and for LH and cortisol responses, respectively, were performed before and after two weeks of administration of a very low dose of estradiol (2.5 ng two times a day). Results: The treatment improved both gonadotropins, mainly LH. The LH response to the GnRH test improved in terms of the peak amplitude, as evaluated using Instantaneous Secretory Rates (ISR) computation. Moreover, when performing the Naloxone test after the treatment interval, FHA patients showed a quicker LH response and recovery of the cortisol response. Conclusions: Our study supports the relevance of very low dose estradiol priming to promote and restore impaired neuroendocrine function in patients with FHA.

Short-term estriol administration modulates hypothalamo-pituitary function in patients with functional hypothalamic amenorrhea (FHA)

OBJECTIVE

To evaluate the influence of short-term estriol administration (10 d) on the hypothalamus-pituitary function and gonadotropins secretion in patients affected by functional hypothalamic amenorrhea (FHA).

STUDY DESIGN

Controlled clinical study on patients with FHA (n = 12) in a clinical research environment.

INTERVENTION(S)

Hormonal determinations and gonadotropin (luteinizing hormone [LH] and FSH) response to a gonadotropin-releasing hormone (GnRH) bolus (10 μg) at baseline condition and after 10 d of therapy with 2 mg/d of estriol per os.

MAIN OUTCOME MEASURE(S)

Measurements of plasma LH, FSH, prolactin, estradiol, androstenedione, 17α-hydroxyprogesterone, insulin, cortisol, thyroid-stimulating hormone, free triiodothyronine, and free thyroxine.

RESULT(S)

After treatment, the FHA patients showed a statistically significant increase of both LH and FSH plasma levels and the significant increase of their responses to the GnRH bolus.

CONCLUSION(S)

Estriol short-term therapy modulates within 10 d of administration the neuroendocrine control of the hypothalamus-pituitary unit and induces the recovery of both gonadotropins synthesis and secretion in hypogonadotropic patients with FHA.

Acetyl-L-carnitine (ALC) administration positively affects reproductive axis in hypogonadotropic women with functional hypothalamic amenorrhea

BACKGROUND

Hypothalamic amenorrhea (HA) is characterized by neuroendocrine impairment that, in turn, negatively modulates endocrine function, mainly within the reproductive axis. HA presents with hypo-LH, hypoestrogenism and, until now, a definite therapeutic strategy has not yet been found. The aim of the following study was to test the efficacy of acetyl-L-carnitine (ALC) administration in HA-affected subjects.

POPULATION

Twenty-four patients affected by stress-induced HA were divided into two groups according to LH plasma levels: group A, hypo-LH (LH≤3 mIU/ml; no.=16), and group B, normo-LH (LH>3 mIU/ml; no.=8), were treated with ALC (1 g/day, per os) for 16 weeks.

DESIGN

Patients underwent baseline hormonal assessment, pulsatility test (for LH and FSH), naloxone test (for LH, FSH and cortisol) both before and after 16 weeks of treatment.

RESULTS

Under ALC administration hypo-LH patients showed a significant increase in LH plasma levels (from 1.4±0.3 to 3.1±0.5 mIU/ml, p<0.01) and in LH pulse amplitude (p<0.001). No changes were observed in the normo-LH group. LH response to naloxone was restored under ALC therapy. Maximal LH response and area under the curve under naloxone were significantly increased (p<0.05 and p<0.01, respectively). No changes were observed in the normo-LH patients.

CONCLUSIONS

Our data support the hypothesis of a specific role of ALC on counteracting the stress-induced abnormalities in hypo-LH patients affected by hypothalamic amenorrhea.

Basic infertility including polycystic ovary syndrome

Infertility in women has many possible causes and must be approached systematically. The most common cause of medically treatable infertility is the polycystic ovary syndrome (PCOS). This syndrome is common in young women and is the cause of anovulatory infertility in 70% of cases. It is therefore an important condition to screen and manage in primary care medical settings. In the past 10 years, insulin sensitization with weight loss or metformin has been shown to be a safe and effective treatment for PCOS infertility that eliminates the risk of multiple pregnancy and may reduce the risk of early pregnancy loss as compared with ovulation-inductor drugs. The authors believe metformin should be considered as first-line therapy because it has the advantage to allow for normal single ovulation, for reduced early pregnancy loss, and, most importantly, lifestyle modifications and weight loss before pregnancy. Losing weight not only improves fertility but also reduces adverse pregnancy outcomes associated with obesity.

Functional hypothalamic amenorrhea: current view on neuroendocrine aberrations

Functional hypothalamic amenorrhea (FHA) is defined as a non-organic and reversible disorder in which the impairment of gonadotropin-releasing hormone (GnRH) pulsatile secretion plays a key role. There are main three types of FHA: stress-related amenorrhea, weight loss-related amenorrhea and exercise-related amenorrhea. The spectrum of GnRH-luteinizing hormone (LH) disturbances in FHA is very broad and includes lower mean frequency of LH pulses, complete absence of LH pulsatility, normal-appearing secretion pattern and higher mean frequency of LH pulses. Precise mechanisms underlying the pathophysiology of FHA are very complex and unclear. Numerous neuropeptides, neurotransmitters and neurosteroids play important roles in the physiological regulation of GnRH pulsatile secretion and there is evidence that different neuropeptides may be involved in the pathophysiology of FHA. Particular attention is paid to such substances as allopregnanolone, neuropeptide Y, corticotropin-releasing hormone, leptin, ghrelin and beta-endorphin. Some studies reveal significant changes in these mentioned substances in patients with FHA. There are also speculations about use some of these substances or their antagonists in the treatment of FHA.

Endocrine profiles and neuropsychologic correlates of functional hypothalamic amenorrhea in adolescents

OBJECTIVE

To determine trigger factors and neuropsychologic correlates of functional hypothalamic amenorrhea (FHA) in adolescence and to evaluate the correlations with the endocrine-metabolic profile.

DESIGN

Cross-sectional comparison of adolescents with FHA and eumenorrheic controls

SETTING

Academic medical institution

PATIENT(S)

Twenty adolescent girls with FHA (aged <18 years) and 20 normal cycling girls

INTERVENTION(S)

All subjects underwent endocrine-gynecologic (hormone) and neuropsychiatric (tests and interview) investigations. A separate semistructured interview was also used to investigate parents.

MAIN OUTCOME MEASURE(S)

Gonadotropins, leptin, prolactin, androgens, estrogens, cortisol, carrier proteins (SHBG, insulin-like growth factor-binding protein 1), and metabolic parameters (insulin, insulin-like growth factor 1, thyroid hormones) were assayed in FHA and control subjects. All girls were evaluated using a test for depression, a test for disordered eating, and a psychodynamic semistructured interview.

RESULT(S)

Adolescents with FHA showed a particular susceptibility to common life events, restrictive disordered eating, depressive traits, and psychosomatic disorders. The endocrine-metabolic profile was strictly correlated to the severity of the psychopathology.

CONCLUSION(S)

Functional hypothalamic amenorrhea in adolescence is due to a particular neuropsychologic vulnerability to stress, probably related to familial relationship styles, expressed by a proportional endocrine impairment.

Clinical evaluation of patients with weight loss-related amenorrhea: neuropeptide Y and luteinizing hormone pulsatility

AIM

To characterize patients with weight loss-related amenorrhea and controls with respect to the pulsatility of neuropeptide Y (NPY) and luteinizing hormone (LH).

SUBJECTS

Nine young women (aged 20.23+/-2.11 years) diagnosed with weight loss-related amenorrhea (body mass index (BMI) 17.52+/-2.43 kg/m2) and five age-matched (age 21.88+/-3.12 years) normally menstruating (every 28-33 days) controls with normal BMI (23.62+/-3.11 kg/m2) (mean value+/-standard deviation).

METHODS

Basal hormonal evaluation included serum follicle-stimulating hormone (FSH), LH, estradiol (E2) and NPY. A pulsatility study investigated NPY and LH episodic release. Patients from control the group were studied during the mid-follicular phase (days 6-8) of the menstrual cycle.

RESULTS

Patients with weight loss-related amenorrhea had lower FSH, LH and E2 levels than controls (p < 0.01). Basal serum NPY levels were lower in amenorrheic patients than in menstruating women (p < 0.01). The numbers of NPY and LH peaks were higher in patients with weigh loss-related amenorrhea than in controls (p < 0.01 and p < 0.05, respectively).

CONCLUSION

Increased NPY pulsatility may have pathophysiological significance in weight loss-related hypothalamic amenorrhea.

Effects of cyproheptadine clorhydrate, a serotonin receptor antagonist, on endocrine parameters in weight-loss related amenorrhea

The aim of the study was to evaluate the possible interactions and/or modulations of the serotoninergic system on hormonal parameters and the reproductive axis in amenorrheic subjects. Hypogonadotropic, underweight, amenorrheic patients (n = 8) were studied before and during cyproheptadine clorhydrate administration (4 mg/day for 3 months). A pulsatility study (4 hours, sampling every 10 minutes) and a naloxone test were performed before and after 4 and 12 weeks of treatment. Plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), estradiol, thryoid-stimulating hormone (TSH), free tri-iodothyronine (fT3), free thyroxine (fT4) and total tri-iodothyonine (total T3), insulin-like growth factor-I (IGF-I) concentrations were determined. Pulse detection analysis was performed using the DETECT program. Serotoninergic receptor blockade affected neither the naloxone-inducted LH response nor the gonadotropin pulsatile parameters. Body mass index (BMI) did not vary; conversely, integrated mean gonadotropins, GH and fT3 concentrations increased during the treatment. In conclusion, cyproheptadine administration affects some of the abnormal endocrine parameters of underweight amenorrheic subjects with no modulation of the opioidergic system. It is likely that the gonadotropin and the fT3 increases take place owing to a change in the metabolic signals modulating hypothalamic function and/or an increased energy availability. Our study suggests a specific central effect of cyproheptadine on the serotonergic pathway controlling food intake at the hypothalamic level.

Estrogen replacement therapy modulates spontaneous GH secretion but does not affect GH-RH-induced GH response and low T3 syndrome in women with hypothalamic amenorrhea associated to weight-loss

Severe dieting and negative energy balance usually lead to the occurrence of amenorrhea together with several endocrine disturbances such as the "low T3 syndrome" and an abnormal GH secretion. To evaluate whether estrogen replacement therapy (ERT) affects thyroid hormones and GH secretion, two groups of patients affected by weight-loss-related amenorrhea and with low plasma T3 levels were treated with two different schedules of ERT using 50 or 100 micrograms estradiol transdermal patches twice a week (Dermestril, Rottapharm, Monza, Italy). Before and after 5 weeks of therapy in each patient thyroid hormones, spontaneous GH secretion and GH-RH-induced GH release were evaluated. After ERT, plasma GH and IGF-1 levels increased in both groups and a consistent change in GH spontaneous release was observed. Conversely the low T3 plasma levels and GH-RH-induced GH response were not modified by ERT. Our present data suggest that in amenorrhea related to weight-loss, hormonal abnormalities are only in part dependent from the hypoestrogenic condition.

Oral glucose challenge effects on growth and sex steroid hormones in normal women and women with hypothalamic amenorrhea

OBJECTIVE

To investigate the effect of growth hormone (GH) on the serum levels of ovarian and adrenal sex steroid hormones in women with hypothalamic amenorrhea (HA).

METHODS

A standard 75-g oral glucose tolerance test (OGTT) was performed in 12 normal women and 16 women with stress-related or weight-loss-related amenorrhea.

RESULTS

Significant progressive declines in GH, testosterone (T), estradiol (E2) and dehydroepiandrosterone sulfate (DHEAS) were observed during the OGTT in the normal and HA groups. Significant positive correlations were observed between GH and T, E2 and DHEAS. The area under the curve (AUC) for the GH response was significantly greater in the HA group than in the normal group. The ratio of the AUC of insulin-like growth factor to that of GH was significantly lower in the HA group.

CONCLUSIONS

Growth hormone may modify ovarian and adrenal sex steroidogenic responses to tropic hormones. A significant degree of GH resistance exists in HA patients. This GH resistance may be related to an ovulatory disturbance.

Hypothalamic amenorrhea and cardiovascular hormones: changes of plasma calcitonin gene-related peptide and atrial natriuretic peptide levels

Typical modifications of cardiovascular activity and water and salt homeostasis throughout female reproductive life are well known. Differences in plasma levels of calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP) have been observed in conditions characterized by different estrogenic levels, suggesting a correlation between female reproductive function and these cardiovascular hormones. The aim of our study was to investigate in hypothalamic amenorrhea the relationship between estrogen deficiency and plasma ANP and CGRP response to adaptive tests (saline infusion test and upright posture test, respectively). Women with hypothalamic amenorrhea (aged 18-28 years) (n = 6) and age-matched healthy controls (n = 6) underwent both functional tests. Plasma CGRP and ANP levels were measured by specific radioimmunoassays before and in course of the tests. Basal plasma CGRP levels of amenorrheic patients did not significantly differ from those of normal women, while basal plasma ANP levels were significantly higher compared to controls (p < 0.01). In amenorrheic women, plasma CGRP levels showed a significant increase in response to upright posture test, though lower than the increase observed in normal women. In contrast, saline infusion test determined a significant increase in plasma ANP levels only in control subjects. In women with hypothalamic amenorrhea, the altered response of CGRP and ANP to adaptive stimuli indicates a partial derangement in the control of the secretion of these cardiovascular hormones. Nevertheless, the differences between such modifications and those observed in other conditions of altered estrogenic levels, suggest that in amenorrheic women hypogonadism is not the major factor influencing CGRP and ANP response to adaptive stimuli.

The transition from pubertal development to postmenopause discloses a gonadotropin-releasing hormone-independent mechanism regulating follicle-stimulating hormone release

The reproductive function is tightly dependent on gonadotropin secretion and the optimal activity of the hypothalamus-pituitary axis. This study discusses evidence that supports the possible existence of a GnRH-independent modulator of FSH secretion in humans. Such a hypothesis has been consistently reported in several experimental animals. To test the hypothesis specific times during the physiological development and activity of the hypothalamus-pituitary axis have been evaluated under the use of drugs acting directly on hypothalamic GnRH-secreting neurons, such as GnRH agonists. The possible presence also in humans of such an independent FSH stimulator might be important for the understanding of anovulation and infertility.