Plasma orexin-A levels in postmenopausal women: possible interaction with estrogen and correlation with cardiovascular risk status

Updates in nonhormonal therapy for perimenopausal and menopausal symptoms

PURPOSE OF REVIEW

Perimenopausal and menopausal symptoms are common and may significantly impact quality of life. Menopausal hormone therapy is the most effective treatment but may not be appropriate in all cases. Nonhormonal alternatives range from lifestyle changes and dietary supplements to medical interventions and prescription therapies. This review will summarize the newest advancements in nonhormonal therapies for bothersome perimenopausal and menopausal symptoms.

RECENT FINDINGS

The Menopause Society recently updated their recommendations and guidelines for nonhormonal therapies. Previous recommendations, such as clonidine and pregabalin, are no longer recommended. A new class of medication, neurokinin B antagonists, are now available to target vasomotor symptoms and show promise in addressing sleep and mood issues.

SUMMARY

Well tolerated, effective nonhormonal therapies are available to address perimenopausal and menopausal symptoms for those patients who are not candidates for or chose not to use menopausal hormone therapy.

Different temporal relationship between sex hormones and sleep status in midlife women: a longitudinal cohort study

Background

Fluctuation in sex hormones and the occurrence of sleep disturbance are 2 major health challenges among midlife women. However, the temporal relationship between them remains unclear.

Methods

This study included 2488 females (mean ± SD age, 49.0 ± 2.70 years) with an average follow-up of 6.95 years. We constructed a composite score by summing items related to sleep problems to reflect the comprehensive sleep status of the participants in the Study of Women's Health Across the Nation. Cross-lagged path analysis was used to examine the temporal relationship between sex hormones and sleep status. Sensitivity analyses were conducted in nonoverweight and overweight groups and adjusted for vasomotor symptoms in the main model.

Aim

In this study, we aimed to examine the temporal relationship between sex hormones and sleep status in midlife women using cross-lagged path analysis.

Outcomes

The primary outcomes included results of the cross-lagged path analysis between sex hormones and sleep status.

Results

After adjusting for age, race, income, menopausal status, body mass index, hormone therapy use, smoking, and drinking, the cross-lagged path coefficients from baseline follicle-stimulating hormone (FSH) and estradiol (E2) to follow-up sleep status were 0.054 (P = .017) and -0.054 (P = .016), respectively. The path coefficient from baseline sleep to follow-up dehydroepiandrosterone sulfate (DHAS) was 0.042 (P = .017). The path coefficients between testosterone and sleep were not statistically significant. In the nonoverweight group, the patterns of the temporal relationship between sex hormones and sleep were the same as the total sample, and the point estimates were larger. However, the temporal relationships in the overweight group were nonsignificant. After adjustment for vasomotor symptoms in the main model, results were basically consistent.

Clinical Implications

Given the temporal relationship between sex hormones and sleep, our findings will provide scientific perspectives to benefit health management in the transition of menopause.

Strengths and Limitations

This study used a longitudinal theoretical model to distinguish the temporal relationship between sex hormones and sleep status in midlife women. Limitations include limited causal evidence in observational studies, unknown confounders, and careful extrapolation.

Conclusion

There were distinct patterns in the unidirectional temporal relationship between (1) FSH, E2, and DHAS and (2) sleep. Changes in FSH and E2 occurred earlier than the change of sleep, while the change of DHAS was later. In contrast, there was no temporal relationship between testosterone and sleep.

Transfer of preclinical study data on the influence of cimicifuga racemosaon functional changes in the hippocampus during menopause

Menopausal transition in women involves complex neurobiochemical changes linked to ovarian dysfunction, resulting in symptoms like vasomotor symptoms (VMS), sleep disturbances, anxiety, and cognitive impairments. Hormone replacement therapy is the first-line treatment. However, many women are reluctant to use HRT or have contraindications toward HRT and seek for alternatives. Non-hormonal therapies with extracts of Cimicifuga racemosa rhizomes like the isopropanolic extract (iCR, black cohosh) offer a promising alternative. A preclinical pilot study exploring iCR's effects on gene expression in the hippocampus and hypothalamus of ovarectomized (OVX) rats mimicking menopausal conditions identified important signaling pathways and CNS-based contributions to the multitargeted modes of action of iCR. Especially in the hippocampus, iCR compensated effects of OVX on gene expression profiles. These changes are reflected by the genes AVPR1A, GAL, CALCA, HCRT, PNOC, ESR1, ESR2 and TAC3 contributing to the formation of hot flushes or thermoregulation as well as to secondary effects such as blood pressure, metabolism, hormonal regulation, homeostasis, mood regulation, neuroendocrine modulation, regulation of sleep and arousal, and in learning, memory and cognition. To understand the mechanisms in the brain of estrogen-depressed animals (OVX) and subsequent iCR treatment we combined the results of the pilot study with those of up-to-date literature and tried to transfer the current knowledge to humans during menopausal transition and adaptation. Focus was laid on changes in the hippocampal function, that is disturbed by hormonal fluctuations, but can also be brought back into balance by iCR.

Non-hormonal pharmacological interventions for managing vasomotor symptoms-how can we help: 2024 landscape

BACKGROUND

Vasomotor symptoms (VMS) affect 70% of menopausal women and are considered as hallmark symptoms of the menopausal transition experienced by over three quarters of women and severely by 25% of women. Estrogen withdrawal alone is not fully responsible for the onset of the menopausal vasomotor symptoms and the mechanism of altered thermoregulation appears to be centrally mediated with alterations in hypothalamic neurotransmitters playing a key part. The loss of thermoregulatory control coexists with the altered Kisspeptin- Neurokinin B-Dynorphin-expressing (KNDy) neurons of the arcuate nucleus signaling triggered by menopause.

OBJECTIVE

Aim of the review was to explore evidence-based non-hormonal pharmacological interventions for treating vasomotor symptoms.

METHODS

Comprehensive overview of relevant literature.

CONCLUSIONS

In the population where, hormonal options are contraindicated or not preferred by the patient, it is essential to explore evidence-based non-hormonal pharmacological interventions for treating vasomotor symptoms. The 2024 landscape of available treatments has expanded yet again, arming the providers with an even wider range of possibilities to help their patients. Fezolinetant, is the first NK3R antagonist developed for the purpose of treating hot flashes in menopausal women. NK3R antagonists provide a safe and effective treatment option for managing menopausal women with VMS.

The 2023 nonhormone therapy position statement of The North American Menopause Society

OBJECTIVE

To update the evidence-based Nonhormonal Management of Menopause-Associated Vasomotor Symptoms: 2015 Position Statement of The North American Menopause Society.

METHODS

An advisory panel of clinicians and research experts in women's health were selected to review and evaluate the literature published since the Nonhormonal Management of Menopause-Associated Vasomotor Symptoms: 2015 Position Statement of The North American Menopause Society. Topics were divided into five sections for ease of review: lifestyle; mind-body techniques; prescription therapies; dietary supplements; and acupuncture, other treatments, and technologies. The panel assessed the most current and available literature to determine whether to recommend or not recommend use based on these levels of evidence: Level I, good and consistent scientific evidence; Level II, limited or inconsistent scientific evidence, and Level III, consensus and expert opinion.

RESULTS

Evidence-based review of the literature resulted in several nonhormone options for the treatment of vasomotor symptoms. Recommended: Cognitive-behavioral therapy, clinical hypnosis, selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitors, gabapentin, fezolinetant (Level I); oxybutynin (Levels I-II); weight loss, stellate ganglion block (Levels II-III). Not recommended: Paced respiration (Level I); supplements/herbal remedies (Levels I-II); cooling techniques, avoiding triggers, exercise, yoga, mindfulness-based intervention, relaxation, suvorexant, soy foods and soy extracts, soy metabolite equol, cannabinoids, acupuncture, calibration of neural oscillations (Level II); chiropractic interventions, clonidine; (Levels I-III); dietary modification and pregabalin (Level III).

CONCLUSION

Hormone therapy remains the most effective treatment for vasomotor symptoms and should be considered in menopausal women within 10 years of their final menstrual periods. For women who are not good candidates for hormone therapy because of contraindications (eg, estrogen-dependent cancers or cardiovascular disease) or personal preference, it is important for healthcare professionals to be well informed about nonhormone treatment options for reducing vasomotor symptoms that are supported by the evidence.

The effect of orexin on the hypoxic ventilatory response of female rats is greatest in the active phase during diestrus

We recently showed that in male rats, orexin contributes to the hypoxic ventilatory response (HVR), with a stronger effect in the active phase. The effect of orexin on the HVR in females has not been investigated. As estrogen can inhibit orexin neurons, here we hypothesized that orexin neurons are activated by hypoxia and facilitate the HVR only in diestrus, when estrogen is low. We exposed female rats (n = 10) to near-isocapnic hypoxia ([Formula: see text] from 0.21 to 0.09) over ∼5 min, after vehicle and again after suvorexant (a dual OxR antagonist; 20 mg/kg ip), with ventilation measured using whole body plethysmography. Each rat was tested in proestrus or estrus (p/estrus), and again in diestrus, during both inactive and active phases. We also performed immunohistochemistry (IHC) to determine the proportion of orexin neurons activated by acute hypoxia during diestrus (n = 6) or proestrus/estrus (n = 6) in the active phase. In the inactive phase, the HVR was unaffected by OxR blockade, irrespective of estrus stage. In the active phase, the effect of OxR blockade depended on stage: the slope of the HVR was significantly reduced by OxR blockade only during diestrus. IHC revealed that hypoxia activated more orexin neurons during diestrus compared with p/estrus. We conclude that in females, orexin neurons are activated by hypoxia and contribute to the HVR only in diestrus when estrogen levels are low. Stage of the estrus cycle should be considered when examining the physiological function of orexin neurons in females.NEW & NOTEWORTHY We previously showed that orexin facilitates the hypoxic ventilatory response (HVR) of adult male rats during the active phase. Others have shown that estrogen inhibits orexin neurons. Here we show that orexin neurons are activated by hypoxia and facilitate the HVR of adult female rats during the active phase, but only in diestrus. These data suggest that orexin neurons facilitate the HVR in females when they are free from the inhibitory effects of estrogen.

Estradiol-dependent hypocretinergic/orexinergic behaviors throughout the estrous cycle

RATIONALE

The female menstrual or estrous cycle and its associated fluctuations in circulating estradiol (E2), progesterone, and other gonadal hormones alter orexin or hypocretin peptide production and receptor activity. Depending on the estrous cycle phase, the transcription of prepro-orexin mRNA, post-translational modification of orexin peptide, and abundance of orexin receptors change in a brain region-specific manner. The most dramatic changes occur in the hypothalamus, which is considered the starting point of the hypothalamic-pituitary-gonadal axis as well as the hub of orexin-producing neurons. Thus, hypothalamus-regulated behaviors, including arousal, feeding, reward processing, and the stress response depend on coordinated efforts between E2, progesterone, and the orexin system. Given the rise of orexin therapeutics for various neuropsychiatric conditions including insomnia and affective disorders, it is important to delineate the behavioral outcomes of this drug class in both sexes, as well as within different time points of the female reproductive cycle.

OBJECTIVES

Summarize how the menstrual or estrous cycle affects orexin system functionality in animal models in order to predict how orexin pharmacotherapies exert varying degrees of behavioral effects across the dynamic hormonal milieu.

Orexin/hypocretin system dysfunction in patients with Takotsubo syndrome: A novel pathophysiological explanation

Takotsubo syndrome (TTS) is an acute heart failure syndrome. Emotional or physical stressors are believed to precipitate TTS, while the pathophysiological mechanism is not yet completely understood. During the coronavirus disease (COVID-19) pandemic, an increased incidence of TTS has been reported in some countries; however, the precise pathophysiological mechanism for developing TTS with acute COVID-19 infection is unknown. Nevertheless, observing the symptoms of COVID-19 might lead to new perspectives in understanding TTS pathophysiology, as some of the symptoms of the COVID-19 infection could be assessed in the context of an orexin/hypocretin-system dysfunction. Orexin/hypocretin is a cardiorespiratory neuromodulator that acts on two orexin receptors widely distributed in the brain and peripheral tissues. In COVID-19 patients, autoantibodies against one of these orexin receptors have been reported. Orexin-system dysfunction affects a variety of systems in an organism. Here, we review the influence of orexin-system dysfunction on the cardiovascular system to propose its connection with TTS. We propose that orexin-system dysfunction is a potential novel explanation for the pathophysiology of TTS due to direct or indirect dynamics of orexin signaling, which could influence cardiac contractility. This is in line with the conceptualization of TTS as a cardiovascular syndrome rather than merely a cardiac abnormality or cardiomyopathy. To the best of our knowledge, this is the first publication to present a plausible connection between TTS and orexin-system dysfunction. We hope that this novel hypothesis will inspire comprehensive studies regarding orexin's role in TTS pathophysiology. Furthermore, confirmation of this plausible pathophysiological mechanism could contribute to the development of orexin-based therapeutics in the treatment and prevention of TTS.

Disruption of Sleep Continuity During the Perimenopause: Associations with Female Reproductive Hormone Profiles

CONTEXT

Nocturnal vasomotor symptoms (nVMS), depressive symptoms (DepSx), and female reproductive hormone changes contribute to perimenopause-associated disruption in sleep continuity. Hormonal changes underlie both nVMS and DepSx. However, their association with sleep continuity parameters resulting in perimenopause-associated sleep disruption remains unclear.

OBJECTIVE

We aimed to determine the association between female reproductive hormones and perimenopausal sleep discontinuity independent of nVMS and DepSx.

METHODS

Daily sleep and VMS diaries, and weekly serum assays of female reproductive hormones were obtained for 8 consecutive weeks in 45 perimenopausal women with mild DepSx but no primary sleep disorder. Generalized estimating equations were used to examine associations of estradiol, progesterone, and follicle stimulating hormone (FSH) with mean number of nightly awakenings, wakefulness after sleep onset (WASO) and sleep-onset latency (SOL) adjusting for nVMS and DepSx.

RESULTS

Sleep disruption was common (median 1.5 awakenings/night, WASO 24.3 and SOL 20.0 minutes). More awakenings were associated with estradiol levels in the postmenopausal range (β = 0.14; 95% CI, 0.04 to 0.24; P = 0.007), and higher FSH levels (β [1-unit increase] = 0.12; 95% CI, 0.02 to 0.22; P = 0.02), but not with progesterone (β [1-unit increase] = -0.02; 95% CI, -0.06 to 0.01; P = 0.20) in adjusted models. Female reproductive hormones were not associated with WASO or SOL.

CONCLUSION

Associations of more awakenings with lower estradiol and higher FSH levels provide support for a perimenopause-associated sleep discontinuity condition that is linked with female reproductive hormone changes, independent of nVMS and DepSx.

A double-blind, randomized, placebo-controlled trial of suvorexant for the treatment of vasomotor symptom-associated insomnia disorder in midlife women

Study Objectives

The neuropeptide orexin promotes wakefulness, modulates thermoregulation, increases after menopause, and is normalized in women receiving estrogen therapy, suggesting a role for orexin antagonism as a treatment for the vasomotor symptom (VMS)-associated insomnia disorder. We tested the efficacy of the dual orexin receptor antagonist suvorexant for chronic insomnia related to nighttime VMS.

Methods

In a double-blind, placebo-controlled trial, 56 women with chronic insomnia associated with nighttime VMS, Insomnia Severity Index (ISI) scores ≥15, and >30 min of diary-rated wake after sleep-onset (WASO) were randomized to receive oral suvorexant 10–20 mg (n = 27) or placebo (n = 29) nightly for 4 weeks. Analysis of within-person change in ISI was adjusted for baseline ISI and race.

Results

Mean baseline ISI scores were 18.1 (95% CI, 16.8 to 19.4) and 18.3 (95% CI, 17.2 to 19.5) in the suvorexant and placebo groups, respectively (p = .81). The average 4-week ISI within-person decrease from baseline was greater on suvorexant (−8.1 [95% CI, −10.2 to −6.0]) compared to placebo (−5.6 [95% CI, −7.4 to −3.9], p = .04). Compared to placebo, nighttime diary-rated VMS frequency was significantly reduced with suvorexant (p < .01). While diary-rated WASO and total sleep time trended toward improvement on suvorexant, findings were not significant after adjustment for multiple comparisons. Daytime VMS and other sleep-related outcomes did not differ between groups. Suvorexant was well tolerated.

Conclusion

These results suggest that suvorexant is likely a well-tolerated and efficacious treatment for VMS-associated insomnia disorder and reduces nighttime VMS. Antagonism of orexin receptors could provide a novel therapeutic option for midlife women with VMS-associated chronic insomnia.

Clinical Trial Information

Efficacy of Suvorexant in the Treatment of Hot Flash-associated Insomnia, https://clinicaltrials.gov/ct2/show/NCT03034018, ClinicalTrials.gov Identifier: NCT03034018.

Disruption of estradiol regulation of orexin neurons: a novel mechanism in excessive ventilatory response to CO2 inhalation in a female rat model of panic disorder

Panic disorder (PD) is ~2 times more frequent in women. An excessive ventilatory response to CO2 inhalation is more likely during the premenstrual phase. While ovarian hormones appear important in the pathophysiology of PD, their role remains poorly understood as female animals are rarely used in pre-clinical studies. Using neonatal maternal separation (NMS) to induce a "PD-like" respiratory phenotype, we tested the hypothesis that NMS disrupts hormonal regulation of the ventilatory response to CO2 in female rats. We then determined whether NMS attenuates the inhibitory actions of 17-β estradiol (E2) on orexin neurons (ORX). Pups were exposed to NMS (3 h/day; postnatal day 3-12). The ventilatory response to CO2-inhalation was tested before puberty, across the estrus cycle, and following ovariectomy. Plasma E2 and hypothalamic ORXA were measured. The effect of an ORX1 antagonist (SB334867; 15 mg/kg) on the CO2 response was tested. Excitatory postsynaptic currents (EPSCs) were recorded from ORX neurons using whole-cell patch-clamp. NMS-related increase in the CO2 response was observed only when ovaries were functional; the largest ventilation was observed during proestrus. SB334867 blocked this effect. NMS augmented levels of ORXA in hypothalamus extracts. EPSC frequency varied according to basal plasma E2 levels across the estrus cycle in controls but not NMS. NMS reproduces developmental and cyclic changes of respiratory manifestations of PD. NMS disrupts the inhibitory actions of E2 on the respiratory network. Impaired E2-related inhibition of ORX neurons during proestrus is a novel mechanism in respiratory manifestations of PD in females.

Associations of plasma hypocretin-1 with metabolic and reproductive health: Two systematic reviews of clinical studies

The hypocretin system consists of two peptides hypocretin-1 and hypocretin-2 (HCRT1 and HCRT2). Hypocretin-containing neurons are located in the posterior and lateral hypothalamus, and have widespread projections throughout the brain and spinal cord. In addition to its presence in the cerebrospinal fluid (CSF), peripheral HCRT1 has been detected in plasma. Robust experimental evidence demonstrates functions of hypothalamic-originated HCRT1 in regulation of multiple biological systems related to sleep-wake states, energy homeostasis and endocrine function. In contrast, HCRT1 studies with human participants are limited by the necessarily invasive assessment of CSF HCRT1 to patients with underlying morbidity. Regulation by HCRT1 of energy homeostasis and reproduction in animals suggests similar regulation in humans and prompts these two systematic reviews. These reviews translate prior experimental findings from animal studies to humans and examine associations between HCRT1 and: 1) metabolic risk factors; 2) reproductive function in men, women and children. A total of 21 studies and six studies met the inclusion criteria for the two searches, respectively. Research question, study design, study population, assessments of HCRT1, reproductive, cardiometabolic data and main findings were extracted. Associations between HCRT1, metabolic and reproductive function are inconsistent. Limitations of studies and future research directions are outlined.

Orexin and Alzheimer's Disease: A New Perspective

Orexin's role in human cognition has recently been emphasized and emerging evidences indicate its close relationship with Alzheimer's disease (AD). This review aimed to demonstrate recent research on the relationship between orexin and AD. Orexin's role in stress regulation and memory is discussed, with significant findings related to sexual disparities in stress response, with potential clinical implications pertaining to AD pathology. There are controversies regarding the orexin levels in AD patients, but the role of orexin in the trajectory of AD is still emphasized in recent literatures. Orexin is also accentuated in the context of tau pathology, and orexin as a potential therapeutic target for AD is frequently discussed. Future directions with regard to the relationship between orexin and AD are suggested: 1) consideration for AD trajectory in the measurement of orexin levels, 2) the need for objective measure such as polysomnography and actigraphy, 3) the need for close observation of cognitive profiles of orexin-deficient narcolepsy patients, 4) the need for validation studies by neuroimaging 5) the need for taking account sexual disparities in orexinergic activiation, and 6) consideration for orexin's role as a stress regulator. The aforementioned new perspectives could help unravel the relationship between orexin and AD.

Linking Cigarette Smoking/Tobacco Exposure and Cluster Headache: A Pathogenesis Theory

INTRODUCTION

To propose a hypothesis theory to establish a linkage between cigarette smoking and cluster headache pathogenesis.

BACKGROUND

Cluster headache is a primary headache syndrome grouped under the trigeminal autonomic cephalalgias. What distinguishes cluster headache from all other primary headache conditions is its inherent connection to cigarette smoking. It is undeniable that tobacco exposure is in some manner related to cluster headache. The connection to tobacco exposure for cluster headache is so strong that even if an individual sufferer never smoked, then that individual typically had significant secondary smoke exposure as a child from parental smoking behavior and in many instances both scenarios exist. The manner by which cigarette smoking is connected to cluster headache pathogenesis is unknown at present. If this could be determined this may contribute to advancing our understanding of cluster headache pathophysiology.

METHODS/RESULTS

Hypothesis statement.

CONCLUSION

The hypothesis theory will include several principles: (1) the need of double lifetime tobacco exposure, (2) that cadmium is possibly the primary agent in cigarette smoke that leads to hypothalamic-pituitary-gonadal axis toxicity promoting cluster headache, (3) that the estrogenization of the brain and its specific sexually dimorphic nuclei is necessary to develop cluster headache with tobacco exposure, and (4) that the chronic effects of smoking and its toxic metabolites including cadmium and nicotine on the cortex are contributing to the morphometric and orexin alterations that have been previously attributed to the primary headache disorder itself.

Effects of orexins on 17β-estradiol synthesis and P450 aromatase modulation in the testis of alpaca (Vicugna pacos)

The steroidogenic enzyme P450 aromatase (ARO) has a key role in the conversion of testosterone (T) into estrogens (E), expressed as 17β-estradiol. The presence and localization of this key enzyme have not been described before in the South American camelid alpaca (Vicugna pacos). In our previous studies of the expression and biological effects of orexin A (OxA) and OxB on the alpaca testis demonstrated that OxA, via its specific receptor 1 (OX1R), stimulated T synthesis. In order to extend these findings, we presently explored the presence and localization of ARO in the alpaca male gonad, and the possible correlation between ARO and the orexinergic complex. Western blotting and immunohistochemistry demonstrated the presence of ARO in tissue homogenates and its localization in the tubular and interstitial compartments of the alpaca testis, respectively. The addition of OxA to fresh testicular slices decreased the 17β-estradiol E levels. This effect was annulled by the sequential addition of the selective OX1R antagonist, SB-408124. OxB incubation did not have any effect on the biosynthesis of E. Furthermore, the OxA-mediated down-regulation of E secretion could be ascribed to ARO inhibition by exogenous OxA, as indicated by measurement of ARO activity in tissue slices incubated with OxA. Overall, our findings suggest that locally secreted OxA interacting with OX1R could indirectly inhibit ARO activity, disabling the conversion of T to E, and consequently lowering E biosynthesis and increasing the production of T in mammalian testis.

Role of Sex Hormones in the Control of Vegetative and Metabolic Functions of Middle-Aged Women

Aims: In women's life, menopause is characterized by significant physiological changes often associated with an increase in body mass and obesity-associated sicknesses. Numerous researches described interdependencies of estrogen deficiency, aging, and resting energy expenditure (REE) downfall in the obesity correlated with the menopause. The aim of this study was to determining whether healthy, obese menopausal women underwent HRT treatment, showed changes in their REE, autonomic asset, and assessment of oxidative stress in comparison with obese pre- and post-menopausal women.

Methodology: In this study, we measured the body composition, the REE, the oxidative stress, the diet assimilation, and the autonomic nervous system activity in three groups: pre-menopause women (n = 50), post-menopause women following hormone-replacement therapy (HRT; n = 50), and post-menopause women not following HRT (n = 50).

Results: In the group with HRT a significant increase of the sympathetic activity and REE was described. Finally this group showed a notable increment of oxidative stress compared with the others, and utilizing BIA instrument, the free fat mass was increased respect to the fat mass of obese women.

Conclusion: The study highlights the importance of the HRT-related physiological changes that influence body weight in menopause women. This results are important because have a practical implications for prevention and/or treatment of the obesity.

Plasma orexin A levels in recently menopausal women during and 3 years following use of hormone therapy

OBJECTIVE

Alterations in sleep quality and metabolism during menopause are improved by menopausal hormone therapy (MHT). The mechanisms mediating these effects remain unclear. Orexin A (OxA) is a neuro-peptide that regulates sleep/wakefulness, food intake and metabolism. This study examined changes in plasma OxA levels during and after treatment in women from the Kronos Early Estrogen Prevention Study (KEEPS).

METHODS

KEEPS randomized women within three years of menopause to: oral conjugated equine estrogen (o-CEE, 0.45mg/day), transdermal 17β estradiol (t-E2, 50μg/day), or placebo pills and patches for four years. Plasma OxA levels were measured by enzyme immunoassays in fasting blood samples collected annually from KEEPS participants at Mayo Clinic during and three years after MHT. Changes in menopausal symptoms and plasma OxA levels were assessed for treatment differences.

RESULTS

During treatment, OxA levels increased more in women randomized to o-CEE compared with the other groups. Women randomized to either form of MHT demonstrated smaller increases in BMI than those on placebo. Insomnia severity decreased similarly among treatment groups. However, neither changes in sleep nor changes in BMI correlated with changes in plasma OxA levels. Changes in waist circumference correlated positively with changes in plasma OxA levels three years after discontinuation of study treatments.

CONCLUSIONS

Although OxA levels increased only in women randomized to o-CEE, these changes did not correlate with changes in sleep quality or BMI. The modest correlation of OxA levels with waist circumference once study treatments were discontinued suggests that OxA may be modulated through multiple intermediary pathways affected by metabolites of 17β-estradiol. Clinical Trial Registration for KEEPS: NCT00154180.

Adiponectin, orexin A and orexin B concentrations in the serum and uterine luminal fluid during early pregnancy of pigs

Adiponectin is the most abundant adipose-released protein that circulates in human plasma at high concentrations. The neuropeptides orexin A (OXA, hypocretin-1) and orexin B (OXB, hypocretin-2) are derived from a common precursor peptide, prepro-orexin and are produced mainly by neurons located in the lateral hypothalamus. It has been demonstrated that the peptides such as adiponectin and orexins have an important role in the regulation of energy metabolism and neuroendocrine functions. These hormones appear to be implicated in both normal and disturbed pregnancy. The objectives of this study were to determine adiponectin and orexin concentrations in the plasma and uterine luminal fluid (ULF) of pigs during early gestation and to explore the relationships between hormone concentrations and stages of pregnancy. The greatest plasma concentrations of adiponectin were observed on days 15-16 and 27-28 of pregnancy, and the least concentrations were on days 30-32 of gestation and on days 10-11 of the oestrous cycle. In ULF, adiponectin concentrations were greater on days 15-16 of pregnancy and on days 10-11 of the oestrous cycle than on days 10-11 and days 12-13 of pregnancy. The greatest OXA concentrations in the blood plasma were noted on days 10-16 of gestation, and the least OXA concentrations were on days 27-32 of pregnancy and on days 10-11 of the oestrous cycle. Orexin A concentrations in ULF were greater on days 10-11 of the cycle than throughout pregnancy. Serum OXB concentrations were greatest on days 10-11 and 30-32 of pregnancy, and least on days 12-28 of gestation. The greatest OXB concentrations in ULF were on days 10-13 of gestation, and the least OXB concentrations were on days 15-16 of pregnancy. This is first study to demonstrate the presence of adiponectin and orexins in the serum and ULF during early pregnancy of pigs as well as the relationships between adiponectin and orexin concentrations and the stage of pregnancy. The fluctuations in adiponectin and orexin concentrations in the plasma and ULF suggest that the hormones present in ULF are mostly of local origin and that these hormones participate in the processes that accompany early pregnancy.

Orexin-A represses satiety-inducing POMC neurons and contributes to obesity via stimulation of endocannabinoid signaling

In the hypothalamic arcuate nucleus (ARC), proopiomelanocortin (POMC) neurons and the POMC-derived peptide α-melanocyte-stimulating hormone (α-MSH) promote satiety. POMC neurons receive orexin-A (OX-A)-expressing inputs and express both OX-A receptor type 1 (OX-1R) and cannabinoid receptor type 1 (CB1R) on the plasma membrane. OX-A is crucial for the control of wakefulness and energy homeostasis and promotes, in OX-1R-expressing cells, the biosynthesis of the endogenous counterpart of marijuana's psychotropic and appetite-inducing component Δ(9)-tetrahydrocannabinol, i.e., the endocannabinoid 2-arachidonoylglycerol (2-AG), which acts at CB1R. We report that OX-A/OX-1R signaling at POMC neurons promotes 2-AG biosynthesis, hyperphagia, and weight gain by blunting α-MSH production via CB1R-induced and extracellular-signal-regulated kinase 1/2 activation- and STAT3 inhibition-mediated suppression of Pomc gene transcription. Because the systemic pharmacological blockade of OX-1R by SB334867 caused anorectic effects by reducing food intake and body weight, our results unravel a previously unsuspected role for OX-A in endocannabinoid-mediated promotion of appetite by combining OX-induced alertness with food seeking. Notably, increased OX-A trafficking was found in the fibers projecting to the ARC of obese mice (ob/ob and high-fat diet fed) concurrently with elevation of OX-A release in the cerebrospinal fluid and blood of mice. Furthermore, a negative correlation between OX-A and α-MSH serum levels was found in obese mice as well as in human obese subjects (body mass index > 40), in combination with elevation of alanine aminotransferase and γ-glutamyl transferase, two markers of fatty liver disease. These alterations were counteracted by antagonism of OX-1R, thus providing the basis for a therapeutic treatment of these diseases.

Hypothalamic orexin's role in exacerbated cutaneous vasodilation responses to an anxiogenic stimulus in a surgical menopause model

Distressing symptoms such as hot flashes and sleep disturbances affect over 70% of women approaching menopause for an average of 4-7 years, and recent large cohort studies have shown that anxiety and stress are strongly associated with more severe and persistent hot flashes and can induce hot flashes. Although high estrogen doses alleviate symptoms, extended use increases health risks, and current non-hormonal therapies are marginally better than placebo. The lack of effective non-hormonal treatments is largely due to the limited understanding of the mechanisms that underlie menopausal symptoms. One mechanistic pathway that has not been explored is the wake-promoting orexin neuropeptide system. Orexin is exclusively synthesized in the estrogen receptor rich perifornical hypothalamic region, and has an emerging role in anxiety and thermoregulation. In female rodents, estrogens tonically inhibit expression of orexin, and estrogen replacement normalizes severely elevated central orexin levels in postmenopausal women. Using an ovariectomy menopause model, we demonstrated that an anxiogenic compound elicited exacerbated hot flash-associated increases in tail skin temperature (TST, that is blocked with estrogen), and cellular responses in orexin neurons and efferent targets. Furthermore, systemic administration of centrally active, selective orexin 1 or 2 and dual receptor antagonists attenuated or blocked TST responses, respectively. This included the reformulated Suvorexant, which was recently FDA-approved for treating insomnia. Collectively, our data support the hypothesis that dramatic loss of estrogen tone during menopausal states leads to a hyperactive orexin system that contributes to symptoms such as anxiety, insomnia, and more severe hot flashes. Additionally, orexin receptor antagonists may represent a novel non-hormonal therapy for treating menopausal symptoms, with minimal side effects.

Sleep disorders, obesity, and aging: the role of orexin

The hypothalamic neuropeptides orexin A and B (hypocretin 1 and 2) are important homeostatic mediators of central control of energy metabolism and maintenance of sleep/wake states. Dysregulation or loss of orexin signaling has been linked to narcolepsy, obesity, and age-related disorders. In this review, we present an overview of our current understanding of orexin function, focusing on sleep disorders, energy balance, and aging, in both rodents and humans. We first discuss animal models used in studies of obesity and sleep, including loss of function using transgenic or viral-mediated approaches, gain of function models using exogenous delivery of orexin receptor agonist, and naturally-occurring models in which orexin responsiveness varies by individual. We next explore rodent models of orexin in aging, presenting evidence that orexin loss contributes to age-related changes in sleep and energy balance. In the next section, we focus on clinical importance of orexin in human obesity, sleep, and aging. We include discussion of orexin loss in narcolepsy and potential importance of orexin in insomnia, correlations between animal and human studies of age-related decline, and evidence for orexin involvement in age-related changes in cognitive performance. Finally, we present a summary of recent studies of orexin in neurodegenerative disease. We conclude that orexin acts as an integrative homeostatic signal influencing numerous brain regions, and that this pivotal role results in potential dysregulation of multiple physiological processes when orexin signaling is disrupted or lost.

The impact of gender on timeliness of narcolepsy diagnosis

STUDY OBJECTIVES

To examine the impact of gender in narcoleptic patients on timeliness of diagnosis, symptomology, and health and lifestyle impairment.

METHODS

This is a cross-sectional study of 109 consecutive patients (68 women) with newly diagnosed narcolepsy with and without cataplexy, from a University sleep disorders center. Consecutive patients were administered an 8-page questionnaire at the time of their diagnosis regarding sleep habits, medications, and medical conditions, lifestyle impairments, as well as details regarding narcolepsy-related symptoms.

RESULTS

Men and women presented with remarkably similar narcolepsy related symptoms, yet women were more likely to be delayed in diagnosis; 85% of men were likely to be diagnosed by 16 years after symptom onset, compared to 28 years in women. More women were likely to remain undiagnosed at any given time point after symptom onset (hazard ratio for diagnosis of men compared to women 1.53; 95% CI 1.01-2.32; p = 0.04). Men and women reported similar degree of subjective sleepiness as measured by the Epworth Sleepiness Scale (mean 16.2 ± 4.5; p = 0.18), though women demonstrated significantly more severe objective sleepiness on multiple sleep latency testing (MSLT) (mean sleep latency in women = 5.4 min (± 4.1), in men 7.4 min (± 3.5); p = 0.03). Despite being more objectively sleepy, women were less likely to report lifestyle impairments in the areas of personal relationships (71% men, 44% women, p = 0.01) and physical activity (36% men, 16% women, p = 0.02), but were also more likely to self-medicate with caffeine (63.4% men, 82.4% women; p = 0.03).

CONCLUSIONS

Narcolepsy impacts men and women's health and lifestyle differently, and may cause delays diagnosis for women.

Hormonal changes in menopause and orexin-a action

Menopause is a period of significant physiological changes that may be associated with increased body weight and obesity-related diseases. Many researches were conducted to assess the contribution of factors such as estrogen depletion, REE decline, and aging to weight gain. An increase in orexin-A plasma levels, paralleling lower estrogen levels, was found during menopause. Orexins are hypothalamic neuropeptides recently discovered, involved in the regulation of feeding behaviour, sleep-wakefulness rhythm, and neuroendocrine homeostasis. Orexins might offer the missing link between postmenopausal hypoestrogenism and other manifestations of the menopausal syndrome, including appetite and weight changes and increase in cardiovascular risk.