Mechanisms and predictors of menses resumption once normal weight is reached in anorexia nervosa

BACKGROUND

In cases of Anorexia Nervosa (AN), achieving weight gain recovery beyond the lower limits set by the World Health Organization and normalizing classical nutritional markers appears to be essential for most patients. However, this is not always adequate to restore menstrual cycles. This discrepancy can cause concern for both patients and healthcare providers, and can impact the medical management of these individuals. Thus, the purpose of this study was to assess the ability of anthropometric and hormonal factors to predict the resumption of menstrual cycles in individuals with anorexia nervosa upon reaching a normal body weight.

METHOD

Patients with AN who had achieved a normal Body Mass Index but had not yet resumed their menstrual cycles (referred to as ANRec) were evaluated on two occasions: first at visit 1 and then again 6 months later, provided their body weight remained stable over this period (visit 2). Among the 46 ANRec patients who reached visit 2, they were categorized into two groups: 20 with persistent amenorrhea (PA-ANRec) and 26 who had regained their menstrual cycles (RM-ANRec). Anthropometric measurements, several hormone levels, Luteinizing Hormone (LH) pulsatility over a 4-h period, and LH response to gonadotropin-releasing hormone injection (LH/GnRH) were then compared between the two groups at visit 1.

RESULTS

Patients in the RM-ANRec group exhibited higher levels of follicular stimulating hormone, estradiol, inhibin B, LH/GnRH, and lower levels of ghrelin compared to those in the PA-ANRec group. Analysis of Receiver Operating Characteristic curves indicated that having ≥ 2 LH pulses over a 4-h period, LH/GnRH levels ≥ 33 IU/l, and inhibin B levels > 63 pg/ml predicted the resumption of menstrual cycles with a high degree of specificity (87%, 100%, and 100%, respectively) and sensitivity (82%, 80%, and 79%, respectively).

CONCLUSIONS

These three hormonal tests, of which two are straightforward to perform, demonstrated a high predictive accuracy for the resumption of menstrual cycles. They could offer valuable support for the management of individuals with AN upon achieving normalized weight. Negative results from these tests could assist clinicians and patients in maintaining their efforts to attain individualized metabolic targets.

TRIAL REGISTRATION

IORG0004981.

High-Fat Diet Alters LH Secretion and Pulse Frequency in Female Mice in an Estrous Cycle-Dependent Manner

Reproductive fitness in females is susceptible to obesogenic diets. Energy balance and reproduction are tightly regulated, in part, by hypothalamic neurons in the arcuate nucleus (ARC), and high-fat diet (HFD) can steadily increase estradiol levels in rodents. Estradiol regulates the reproductive axis via negative feedback mechanisms in ARC neurons by modulating pulsatile release of the gonadotropin luteinizing hormone (LH). However, it is unclear how the circulating estradiol milieu of adult females interacts with a state of high-caloric fat intake to alter LH pulse dynamics. Here, we used serial tail-tip blood sampling to measure pulsatile LH release at different estrous cycle stages in mice fed a HFD. Starting at 21 days of age, female C57BL/6J mice were freely fed with either regular chow diet (RD) or 60% kcal HFD for 12 weeks. Blood samples were collected once at diestrus, and then again at estrus. LH was measured in 10-minute intervals for 3 hours and analyzed for pulse frequency, amplitude, and mean and basal LH levels. Compared with RD-fed controls, mice fed HFD displayed significantly increased pulse frequency at diestrus, but not at estrus. HFD-fed mice also had lower mean and basal LH levels compared with RD-fed controls, but only during estrus. These data suggest that circulating estradiol can variably contribute to the impact that HFD has on LH pulsatile release and also provide insight into how obesity impacts women's reproductive health when ovarian estradiol levels drastically change, such as during menopause or with hormone replacement therapy.

Neural Determinants of Pulsatile Luteinizing Hormone Secretion in Male Mice

The gonadotrophin-releasing hormone (GnRH) pulse generator drives pulsatile luteinizing hormone (LH) secretion essential for fertility. However, the constraints within which the pulse generator operates to drive efficient LH pulsatility remain unclear. We used optogenetic activation of the arcuate nucleus kisspeptin neurons, recently identified as the GnRH pulse generator, to assess the efficiency of different pulse generator frequencies in driving pulsatile LH secretion in intact freely behaving male mice. Activating the pulse generator at 45-minute intervals generated LH pulses similar to those observed in intact male mice while 9-minute interval stimulation generated LH profiles indistinguishable from gonadectomized (GDX) male mice. However, more frequent activation of the pulse generator resulted in disordered LH secretion. Optogenetic experiments directly activating the distal projections of the GnRH neuron gave the exact same results, indicating the pituitary to be the locus of the high frequency decoding. To evaluate the state-dependent behavior of the pulse generator, the effects of high-frequency activation of the arcuate kisspeptin neurons were compared in GDX and intact mice. The same stimulus resulted in an overall inhibition of LH release in GDX mice but stimulation in intact males. These studies demonstrate that the GnRH pulse generator is the primary determinant of LH pulse profile and that a nonlinear relationship exists between pulse generator frequency and LH pulse frequency. This may underlie the ability of stimulatory inputs to the pulse generator to have opposite effects on LH secretion in intact and GDX animals.

Glutamatergic Transmission to Hypothalamic Kisspeptin Neurons Is Differentially Regulated by Estradiol through Estrogen Receptor α in Adult Female Mice

Estradiol feedback regulates gonadotropin-releasing hormone (GnRH) neurons and subsequent luteinizing hormone (LH) release. Estradiol acts via estrogen receptor α (ERα)-expressing afferents of GnRH neurons, including kisspeptin neurons in the anteroventral periventricular (AVPV) and arcuate nuclei, providing homeostatic feedback on episodic GnRH/LH release as well as positive feedback to control ovulation. Ionotropic glutamate receptors are important for estradiol feedback, but it is not known where they fit in the circuitry. Estradiol-negative feedback decreased glutamatergic transmission to AVPV and increased it to arcuate kisspeptin neurons; positive feedback had the opposite effect. Deletion of ERα in kisspeptin cells decreased glutamate transmission to AVPV neurons and markedly increased it to arcuate kisspeptin neurons, which also exhibited increased spontaneous firing rate. KERKO mice had increased LH pulse frequency, indicating loss of negative feedback. These observations indicate that ERα in kisspeptin cells is required for appropriate differential regulation of these neurons and neuroendocrine output by estradiol.SIGNIFICANCE STATEMENT The brain regulates fertility through gonadotropin-releasing hormone (GnRH) neurons. Ovarian estradiol regulates the pattern of GnRH (negative feedback) and initiates a surge of release that triggers ovulation (positive feedback). GnRH neurons do not express the estrogen receptor needed for feedback (estrogen receptor α [ERα]); kisspeptin neurons in the arcuate and anteroventral periventricular nuclei are postulated to mediate negative and positive feedback, respectively. Here we extend the network through which feedback is mediated by demonstrating that glutamatergic transmission to these kisspeptin populations is differentially regulated during the reproductive cycle and by estradiol. Electrophysiological and in vivo hormone profile experiments on kisspeptin-specific ERα knock-out mice demonstrate that ERα in kisspeptin cells is required for appropriate differential regulation of these neurons and for neuroendocrine output.

Molecular species of prostaglandins involved in modulating luteinising hormone pulses of female rats under infectious stress conditions

Mammalian reproductive function is controlled by the hypothalamic-pituitary-gonadal (HPG) axis, which is suppressed under infectious stress conditions. By analysing the pulsatility of luteinising hormone (LH), we have previously demonstrated that prostaglandins (PGs) in the central nervous system mediate infectious stress to suppress the activity of the HPG axis. The present study aimed to characterise the types of PGs responsible for suppression of the HPG axis. We focused on three major types of PGs: PGE₂ , PGD₂ and PGF_2α . We used female rats overiectomised bilaterally 1 week before the experiments. Lipopolysaccharide (100 μg kg^-1 ) suppressed LH pulses at the same time as enhancing the concentration of all three PGs in the cerebrospinal fluid, which was restored by indomethacin (10 mg kg^-1 ). Subsequently, we observed LH pulsatility after a single injection of each PG and after co-injection of PGE₂ with PGF_2α into the third cerebral ventricle. A single injection of PGE₂ dose-dependently induced a transient increase in mean LH concentration and LH pulse amplitude, and PGD₂ significantly increased the amplitude of LH pulses, wereas PGF_2α did not affect LH pulsatility. On the other hand, co-injection of PGE₂ and PGF_2α induced a significant suppression of both the frequency and amplitude of LH pulses. These results suggest that PGE₂ and PGF_2α can represent two of the mediators that suppress the HPG axis in situations of infectious stress. Moreover, the results imply that there are two contradictory effects of PGE₂ on LH pulsatility: (i) enhancive when working alone and (ii) suppressive when working together with PGF_2α .

Increase of kisspeptin-positive cells in the hypothalamus of a rat model of polycystic ovary syndrome

Kisspeptin, a hypothalamic neuropeptide, is expressed in the arcuate nucleus (ARC) that is considered as the center of the gonadotropin-releasing hormone (GnRH)-pulse generator. We hypothesized that kisspeptin expressed in the ARC is implicated in the disturbance of the hypothalamus-pituitary-ovary axis observed in polycystic ovary syndrome (PCOS). To test this hypothesis, we evaluated the hormonal profiles, luteinizing hormone (LH) pulse, and ARC kisspeptin immunoreactivity in a PCOS rat model using the anti-progestin RU486. We found an alteration of the LH pulse, including a trend towards an increased mean LH concentration and area under the curve, and a significant upregulation of the mean LH pulse amplitude. Additionally, a higher number of kisspeptin-positive cells was observed in the ARC of RU486-treated rats than in the ARC of intact rats. These results suggest the possible involvement of hypothalamic kisspeptin in the hypothalamus-pituitary-ovary axis and therefore, in PCOS pathophysiology.