Search

Context Implantation is a reproductive bottleneck in women, regulated by fluctuations in ovarian steroid hormone concentrations. However, other nuclear receptor ligands are modifiers of endometrial differentiation leading to successful pregnancy. In the present study we analyzed the effects of peroxisome-proliferator-activated receptor β/δ (PPARβ/δ) activation on established cellular biomarkers of human endometrial differentiation (decidualization). Objective The objective of this work is to test the effects of PPARβ/δ ligation on human endometrial cell differentiation. Design Isolated primary human endometrial stromal cells (ESCs) were treated with synthetic (GW0742) or natural (all trans-retinoic acid, RA) ligands of PPARβ/δ, and also with receptor antagonists (GSK0660, PT-S58, and ST247) in the absence or presence of decidualizing hormones (10 nM estradiol, 100 nM progesterone, and 0.5 mM dibutyryl cAMP [3′,5′-cyclic adenosine 5′-monophosphate]). In some cases interleukin (IL)-1β was used as an inflammatory stimulus. Time course and dose-response relationships were evaluated to determine effects on panels of well characterized in vitro biomarkers of decidualization. Results PPARβ/δ, along with estrogen receptor α (ERα) and PR-A and PR-B, were expressed in human endometrial tissue and isolated ESCs. GW0742 treatment enhanced hormone-mediated ESC decidualization in vitro as manifested by upregulation of prolactin, insulin-like growth factor-binding protein 1, IL-11, and vascular endothelial growth factor (VEGF) secretion and also increased expression of ERα, PR-A and PR-B, and connexin 43 (Cx43). RA treatment also increased VEGF, ERα, PR-A, and PR-B and an active, nonphosphorylated isoform of Cx43. IL-1β and PPARβ/δ antagonists inhibited biomarkers of endometrial differentiation. Conclusion Ligands that activate PPARβ/δ augment the in vitro expression of biomarkers of ESC decidualization. By contrast, PPARβ/δ antagonists impaired decidualization markers. Drugs activating these receptors may have therapeutic benefits for embryonic implantation.

Cosponsoring associations The American Society for Reproductive Medicine, the European Society of Endocrinology, and the Pediatric Endocrine Society. This guideline was funded by the Endocrine Society. Objective To formulate clinical practice guidelines for the diagnosis and treatment of functional hypothalamic amenorrhea (FHA). Participants The participants include an Endocrine Society-appointed task force of eight experts, a methodologist, and a medical writer. Evidence This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation approach to describe the strength of recommendations and the quality of evidence. The task force commissioned two systematic reviews and used the best available evidence from other published systematic reviews and individual studies. Consensus process One group meeting, several conference calls, and e-mail communications enabled consensus. Endocrine Society committees and members and cosponsoring organizations reviewed and commented on preliminary drafts of this guideline. Conclusions FHA is a form of chronic anovulation, not due to identifiable organic causes, but often associated with stress, weight loss, excessive exercise, or a combination thereof. Investigations should include assessment of systemic and endocrinologic etiologies, as FHA is a diagnosis of exclusion. A multidisciplinary treatment approach is necessary, including medical, dietary, and mental health support. Medical complications include, among others, bone loss and infertility, and appropriate therapies are under debate and investigation.

Context: Because androgens are obligatory precursors of estrogens, it is reasonable to assume that their serum concentrations would exhibit positive correlations. If so, then epidemiologic studies that examine the association between androgens and pathological processes should adjust the results for the independent effect of estrogens. Objective: The objective of the study was to examine the interrelationships among testosterone (T), androstenedione, estradiol (E2), estrone, and SHBG in postmenopausal women. Design: This was a cross-sectional study of women participating in the National Heart, Blood, and Lung Institute-sponsored Women’s Ischemia Syndrome Evaluation study. Setting: The study was conducted at four academic medical centers. Patients: A total of 284 postmenopausal women with chest pain symptoms or suspected myocardial ischemia. Main Outcome Measures: Post hoc analysis of the relationships among sex steroid hormones with insulin resistance, body mass index (BMI), and presence or absence of coronary artery disease as determined by coronary angiography. Results: BMI was significantly associated with insulin resistance, total E2, free E2, bioavailable E2, and free T. Highly significant correlations were found for total T, free T, and androstenedione with total E2, free E2, bioavailable E2, and estrone and persisted after adjustment for BMI and insulin resistance. A significant relationship was present between total and free T and the presence of coronary artery disease after adjustment for the effect of E2. Conclusions: Serum levels of androgens and estrogens track closely in postmenopausal women referred for coronary angiography for suspected myocardial ischemia. Epidemiological studies that relate sex steroid hormones to physiological or pathological processes need to control for the independent effect of both estrogens and androgens.

During the follicular phase of the menstrual cycle, FSH stimulates follicular growth, granulosa cell aromatase activity, induction of LH receptors on the granulosa cell membrane, and estradiol secretion. As a result of negative feedback of estradiol on the pituitary, serum FSH concentrations decline. Despite the fall in FSH concentrations, the maturing follicle continues to develop to the preovulatory stage. In a prospective randomized trial, we tested the hypothesis that a key mechanism by which the dominant follicle continues to develop in the face of decreasing concentration of FSH is by acquiring LH responsiveness. In 24 women, pituitary gonadotropin secretion was down-regulated with a GnRH agonist. Follicular growth was then stimulated with recombinant human FSH (r-hFSH) until a 14-mm follicle was identified by ultrasound. The women were then randomized to 1 of 4 groups for a 2-day period: continued r-hFSH treatment, substitution of r-hFSH with saline, low dose r-hLH (150 IU, twice daily), or high dose r-hLH (375 IU, twice daily). Serum estradiol concentrations in the women receiving saline declined by the end of the 2-day randomization period. In contrast, serum estradiol concentrations continued to rise in women receiving either r-hFSH or r-hLH compared with those in the saline-treated group (P < 0.05). Pregnancies occurred in each of the gonadotropin treatment groups. These findings indicate that once FSH initiates follicular growth, either FSH or LH is capable of sustaining follicular estradiol production. Extrapolating these findings to the normal menstrual cycle suggests that the maturing follicle may continue to develop in the presence of diminishing FSH concentrations by acquiring the capacity to respond to LH.

Women with hyperandrogenic anovulation (HAA) exhibit increased GnRH drive, as evidenced by a faster LH pulse frequency that slows in response to progestin-induced opioidergic tone. To determine whether increased GnRH-LH drive in HAA reflects altered sex steroid exposure caused by chronic anovulation or is an intrinsic hypothalamic attribute, we compared the pulsatile LH response to oral contraceptive (OC)-induced suppression in seven women with HAA, with that of seven eumenorrheic women (EW). LH levels were determined at 10-min intervals for 12 h after 19–21 days of OC use and 5–7 days after cessation. Testosterone, androstenedione, estradiol, FSH, and LH levels were determined at weekly intervals before, during, and after OC use. LH pulse number/12 h was higher (P < 0.001) in HAA during and after OCs, when compared with that of EW. Mean LH was increased in HAA before, during, and after OCs. Testosterone, androstenedione, and estradiol levels were higher in HAA before OCs, but they decreased to similar levels during OC use in both groups. FSH concentrations were similar before and during OCs but rose more after cessation of OCs in EW. These findings indicate that GnRH drive in HAA is resistant to OC-induced suppression and, therefore, could be an intrinsic hypothalamic attribute.

A constellation of neuroendocrine secretory aberrations, including reduced LH pulse frequency and PRL concentrations, has been documented in women with functional hypothalamic amenorrhea (FHA). As pituitary function was preserved, these aberrations were attributed to an alteration in hypothalamic neuromodulation. To investigate the participation of the dopaminergic system in the genesis of the reduced LH pulse frequency and suppressed PRL levels in FHA, we studied six women with FHA and six cyclic women in the early follicular phase by obtaining blood samples at 15-min intervals for 48 h during sequential 24-h infusions of saline and a dopamine receptor blocker, metoclopramide (MCP). A hypothalamic vs. pituitary site of action was inferred from the pulsatility characteristics. MCP consistently elicited an increase in the LH pulse frequency in the women with FHA [7.3 +/- 1.2 (+/- SE) to 10.5 +/- 1.3 pulses/24 h; P less than 0.005]. In contrast, the eumenorrheic women did not show a significant change in LH pulse frequency in response to MCP (15.2 +/- 1.0 to 14.3 +/- 0.9 pulses/24 h). While the PRL concentrations were significantly lower in the FHA group during the infusion of saline (P less than 0.001) and MCP (P less than 0.005), the relative increases in PRL during MCP were similar in both groups. The acceleration of LH pulse frequency by blockade of dopamine receptors implies that there is increased hypothalamic dopaminergic inhibition of GnRH pulse frequency in women with FHA.

The clinical research study reported herein by Blank et al. (1) identified insulin as the factor that explained the variable sensitivity to progesterone-induced slowing of GnRH-LH drive previously described in Tanner stage 3–5 hyperandrogenic adolescent girls (2). Specifically, the current analysis revealed that resistance of LH pulsatility to progesterone-induced slowing was proportional to fasting insulin in that group. The authors posited that increased GnRH drive in adolescent girls is a form fruste or precursor of polycystic ovary syndrome (PCOS). This line of investigation buttresses the notion that understanding the neuromodulation of GnRH is critical to explicating the pathobiology of PCOS (3). By providing an explicit example of a critical concept in what could be termed combinatorial endocrinology, namely, that the action of a hormone depends on its context, the study also provides another lesson that is not specific to understanding PCOS. Using this latest insight into the brain phenotype of PCOS as an example, we can infer that the final phenotype of other complex syndromes that present with variation in key features likely represents the interaction of several relevant parameters. Context in endocrinology would include not only age and sex but also time of day and current and possibly past endocrine and metabolic status among other variables. The authors found that LH sensitivity to suppression by progesterone was not due to insulin resistance or androgen excess, a notion that has consumed the field for decades, but rather insulin resistance and androgen excess. That both insulin resistance and increased androgen action confer the full brain phenotype in PCOS may explain the group’s earlier results showing that dampening of androgen action with the anti-androgen flutamide restored GnRH-LH sensitivity to progesterone suppression in PCOS (4). An interaction between insulin resistance and androgen excess appears to explain the brain phenotype of PCOS better than either parameter alone. Argument by analogy would suggest that PCOS is unlikely to be the only endocrine syndrome attributable to a complex interaction of multiple parameters. Dichotomization is a fundamental analytic approach used to isolate causality and the foundation of scientific inquiry and design, but it has limits. Unless explicitly built into the study design, dichotomization into an either/or question does not permit a test of interaction. But physiology and pathophysiology reflect systems biology and combinatorial dynamics. Failure to account for interaction likely explains some of why cellular studies often do not a whole organism describe; conversely, understanding context-specific hormone action may well help to put into perspective the physiological relevance of cellular studies. For instance, ovarian steroids have been shown to alter potassium channel functioning on hypothalamic GnRH neurons and to modulate GnRH neuronal output via this mechanism (5, 6). Not surprisingly, K(ATP) channels also mediated responsiveness to glucose and metabolic inhibition (7). The cellular and rodent models help us to understand the mechanisms that might underlie the current pathophysiological results in the uniquely human condition of female adolescent hyperandrogenism and, vice versa, the human results provide a firm rationale for conducting rodent and cellular studies. It is but a small leap to now imagine that alterations of this type in GnRH cellular physiology would confer differential sensitivity to subsequent insulin exposure and that both the past and current hormone soup might determine the functional characteristics of the GnRH pulse generator. Because synergism exists between insulin and LH in theca cells and because that insight helped to explain the ovarian phenotype found in PCOS, it should come as no surprise that the neuroendocrine apparatus would operate similarly. Indeed, when attempting to discern whether stress-induced suppression of GnRH drive was due to psychogenic or energy challenge, we found profound synergism between psychogenic and metabolic challenge (8). Likewise, Gibbs et al. found that estradiol restored learning in aged female rats, but only in the presence of a cholinesterase inhibitor (9). Given these considerations, the astute study designer is advised to consider whether the investigative approach will permit elucidating “and” as well as “or.” In complex disease, adaptations, and aging, the whole really is greater than the sum of the parts. It is time to remember this dictum not only in the clinic when we are treating patients but also in the experimental setting

Hypercortisolism was found in patients with functional hypothalamic amenorrhea (HA) in preliminary short term studies conducted during the morning hours (0800-1100 h). This observation prompted us to characterize the circadian and pulsatile patterns of serum cortisol and LH levels at 15-min intervals for 24 h in 10 women with functional HA and in 7 normal women during the early follicular phase of their cycles. The mean integrated 24-h serum cortisol levels (area under the curve) were significantly (P less than 0.01) higher in the HA patients than in normal women. The mean cortisol levels in the HA patients were elevated (P less than 0.005) compared to those in the normal women during the daytime hours (0800-1600 h), but not during the evening (1600-2400 h) and sleeping hours (2400-0800 h). This selective hypercortisolism during the waking period of the day was almost entirely related to increased duration and amplitude of secretory episodes (peak area) rather than a change in pulse frequency. The serum cortisol increments in response to a noon meal that occurred in normal women were markedly impaired (P less than 0.01) in the HA patients. Compared with that in the normal women, mean LH pulse frequency was reduced by 30% in the HA patients. The 24-h mean LH levels and mean LH pulse amplitude were not significantly different from those in the normal women. However, among the HA patients there were marked individual differences in LH pulse frequency and amplitude, with prolonged interpulse quiescent periods, indicative of dysfunction of the hypothalamic GnRH pulse generator. We conclude that neuroendocrine activation of the ACTH-adrenal axis and inhibition of the GnRH pulse generator in women are associated with HA. Further, spontaneous resumption of normal cyclicity occurred in the majority (8 of 10) of the HA patients with no medical treatment, suggesting that this syndrome is a reversible hypothalamic disorder of a functional nature.

To further elucidate the neuroendocrine regulation of anterior pituitary function in women with functional hypothalamic amenorrhea (FHA), we measured serum LH, FSH, cortisol, GH, PRL, TSH concentrations simultaneously at frequent intervals for 24 h in 10 women with FHA and in 10 normal women in the early follicular phase (NC). Using the same data, we separately analyzed the cortisol-PRL responses to meals in these women. In addition, the pituitary responses to the simultaneous administration of GnRH, CRH, GHRH, and TRH were assessed in 6 FHA and 6 normal women. The 24-h secretory pattern of each hormone except TSH was altered in the women with FHA. Compared to normal women, the women with FHA had a 53% reduction in LH pulse frequency (P less than 0.0001) and an increase in the mean LH interpulse interval (P less than 0.01); LH pulse amplitude was similar. The 24-h integrated LH and FSH concentrations were reduced 30% (P = 0.01) and 19% (P less than 0.05), respectively. The mean cortisol pulse frequency, amplitude, interpulse interval, and duration were similar in the two groups, but integrated 24-h cortisol secretion was 17% higher in the women with FHA (P less than 0.05). This increase was greatest from 0800-1600 h, but also was present from 2400-0800 h. Cortisol levels were similar in the two groups from 1600-2400 h, resulting in an amplified circadian excursion. In contrast, the 24-h serum PRL levels were markedly lower at all times (P less than 0.0001), the sleep-associated nocturnal elevation of PRL was proportionately greater (P less than 0.05), and serum GH levels were increased at night in the women with FHA (P less than 0.05). Although 24-h serum TSH levels were similar at all times, T3 (P less than 0.05) and T4 (P less than 0.01) levels were lower in the FHA women. The responses of serum cortisol to lunch (P less than 0.01) and dinner (P less than 0.05) and those of serum PRL to lunch (P less than 0.05) and dinner (P = 0.08) were blunted in the women with FHA. Pituitary hormone increments in response to the simultaneous iv administration of GnRH, CRH, GHRH, and TRH were similar in the two groups, except for a blunted PRL response to TRH in the women with FHA (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)