Estradiol treatment modulates spontaneous sleep and recovery after sleep deprivation in castrated male rats

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Understanding the Associations of Prenatal Androgen Exposure on Sleep Physiology, Circadian Proteins, Anthropometric Parameters, Hormonal Factors, Quality of Life, and Sex Among Healthy Young Adults: Protocol for an International, Multicenter Study

Background

The ratio of the second finger length to the fourth finger length (2D:4D ratio) is considered to be negatively correlated with prenatal androgen exposure (PAE) and positively correlated with prenatal estrogen. Coincidentally, various brain regions are sensitive to PAE, and their functions in adults may be influenced by the prenatal actions of sex hormones.

Objective

This study aims to assess the relationship between PAE (indicated by the 2D:4D ratio) and various physiological (sex hormone levels and sleep-wake parameters), psychological (mental health), and sexual parameters in healthy young adults.

Methods

This study consists of two phases. In phase 1, we will conduct a survey-based study and anthropometric assessments (including 2D:4D ratio and BMI) in healthy young adults. Using validated questionnaires, we will collect self-reported data on sleep quality, sexual function, sleep chronotype, anxiety, and depressive symptoms. In phase 2, a subsample of phase 1 will undergo polysomnography and physiological and genetic assessments. Sleep architecture data will be obtained using portable polysomnography. The levels of testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, prolactin, melatonin, and circadian regulatory proteins (circadian locomotor output cycles kaput [CLOCK], timeless [TIM], and period [PER]) and the expression levels of some miRNAs will be measured using blood samples. The rest and activity cycle will be monitored using actigraphy for a 7-day period.

Results

In Poland, 720 participants were recruited for phase 1. Among these, 140 completed anthropometric measurements. In addition, 25 participants joined and completed phase 2 data collection. Recruitment from other sites will follow.

Conclusions

Findings from our study may help to better understand the plausible role of PAE in sleep physiology, mental health, and sexual quality of life in young adults.

International Registered Report Identifier (IRRID)

DERR1-10.2196/29199

The Rare Phenomenon of Consecutive Ejaculations in Male Rats

Mounting, intromission and ejaculation are commonly reported sexual behaviours in male rats. In a mating session, they can have several copulatory series with post-ejaculatory intervals in between ejaculations before they reach sexual satiety. Here, we describe a phenomenon where male rats displayed consecutive ejaculations (CE) with a short inter-ejaculatory interval (IEI). Male rats were daily mated with a sexually receptive female rat. Two out of 15 rats displayed CE in one of their mating tests. The first rat had CE at 9.9 and 10.1 min (IEI = 16.3 s) after the start of the test. The second rat showed CE at 28.1 and 28.5 min (IEI = 18.7 s) after the test onset. During the IEI, the rats did not show any mounting or intromission.

Preference for sleep management strategies among prostate cancer patients: An Aotearoa/New Zealand perspective✰

INTRODUCTION

Many men with prostate cancer (PCa) experience insomnia symptoms post-treatment. We explore here PCa patients' preference for strategies to manage their sleep.

PATIENTS AND METHODS

A brief online survey was launched on Facebook and promoted by Prostate Cancer Foundation New Zealand. The survey contained validated questionnaires on various sleep-related parameters, as well as questions about sleep management strategies.

RESULTS

We recruited 82 PCa patients (67.9 ± 6.3 years old). Participants with high insomnia severity index (ISI) scores reported significantly worse daytime sleepiness, more severe fatigue, being less of a "morning person", and more frequent dreaming. Most participants (71-95%) were open to trying behavioural strategies for improving sleep hygiene, especially by improving their sleeping conditions and having a consistent sleep-wake schedule. Insomnia severity and past use of androgen deprivation therapy were significant predictors for the number of sleep treatments used. Participants with a high ISI were more likely to have used medication, CBT, and herbal remedies or supplements for treating sleep issues than those with low ISI. Furthermore, in patients who had not used these treatments options, those with a high ISI were more willing to try CBT and hypnosis compared to those with a low ISI. Reasons for not willing to try various sleep treatments were documented.

CONCLUSION

Most PCa patients are willing to adjust their behavior or lifestyle to improve their sleep habits/behaviours. Patients with severe insomnia are more likely to have both used and express willingness to try, interventions to improve sleep, with preferences for CBT and hypnosis.

Chronic sleep deprivation prolongs the reduction of sexual behaviour associated with daily sexual encounter in male rats

Chronic sleep deprivation (CSD) is common in many societies. Consecutive sleep loss increases allostatic load, which is known to negatively affect health outcomes. We investigated the impact of CSD on male sexual behaviour. Sexually-experienced male Long-Evans rats (singly housed under 14:10 light:dark) were either subjected to CSD or no CSD for 7 days, followed by a 7-day sleep recovery (SR) period. Their sexual behaviours were tested daily during both periods. CSD was performed by a 'gentle-handling' protocol for 4 hours per day, at the end of the light phase. Daily sexual behaviour tests led to a change in sexual behaviour over time. Intromission and ejaculation frequencies declined with repeated testing, but the reduction in these behaviours lasted for a longer period in rats that were previously subjected to CSD. Ejaculation latency was significantly longer towards the end of the recovery period in rats that had undergone CSD, but not in the control group. Post-ejaculatory interval increased and mounting behaviour did not change with daily mating tests, regardless of sleep deprivation protocol. CSD prolongs the decline in sexual behaviours associated with daily sexual encounters in male rats, and thus the return to baseline for these parameters requires days.

Sex- and Age-dependent Differences in Sleep-wake Characteristics of Fisher-344 Rats

Aging is a well-recognized risk factor for sleep disruption. The characteristics of sleep in aging include its disruption by frequent awakenings, a decline in both non-rapid eye movement (nonREM) and REM sleep amounts, and a weaker homeostatic response to sleep loss. Evidence also suggests that sleep in females is more sensitive to changes in the ovarian steroidal milieu. The Fischer-344 rats are commonly used experimental subjects in behavioral and physiological studies, including sleep and aging. Most sleep studies in Fischer-344 rats have used male subjects to avoid interactions between the estrus and sleep-waking cycles. The changes in the sleep-wake organization of female Fischer-344 rats, especially with advancing age, are not well-characterized. We determined sleep-waking features of cycling females across estrus stages. We also compared spontaneous and homeostatic sleep response profiles of young (3-4 months) and old (24-25 months) male and female Fischer-344 rats. The results suggest that: i) sleep-wake architectures across stages of estrus cycle in young females were largely comparable except for a significant suppression of REM sleep at proestrus night and an increase in REM sleep the following day; ii) despite hormonal differences, sleep-wake architecture in male and female rats of corresponding ages were comparable except for the suppression of REM sleep at proestrus night and higher nonREM delta power in recovery sleep; and iii) aging significantly affected sleep-wake amounts, sleep-wake stability, and homeostatic response to sleep loss in both male and female rats and that the adverse effects of aging were largely comparable in both sexes.

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.

Cognitive Impacts of Estrogen Treatment in Androgen-Deprived Males: What Needs to be Resolved

Background:

Many prostate cancer (PCa) patients are on androgen deprivation therapy (ADT) as part of their cancer treatments but ADT may lead to cognitive impairments. ADT depletes men of both androgen and estrogen. Whether estradiol supplementation can improve cognitive impairments in patients on ADT is understudied.

Objective:

To summarize data on the effects of estradiol treatment on cognitive function of androgen-deprived genetic male populations (PCa patients and male-to-female transsexuals) and castrated male animals.

Method:

Publications were identified by a literature search on PubMed and Google Scholar.

Results:

While some studies showed that estradiol improves cognitive function (most notably, spatial ability) for castrated rats, what remains uninvestigated are: 1) whether estradiol can improve cognition after long-term androgen deprivation, 2) how estradiol affects memory retention, and 3) how early vs. delayed estradiol treatment after castration influences cognition. For androgen-deprived genetic males, estradiol treatment may improve some cognitive functions (e.g., verbal and visual memory), but the findings are not consistent due to large variability in the study design between studies.

Conclusion:

Future studies are required to determine the best estradiol treatment protocol to maximize cognitive benefits for androgen-deprived genetic males. Tests that assess comparable cognitive domains in human and rodents are needed. What particularly under-investigated is how the effects of estradiol on cognitive ability intersect with other parameters; sleep, depression and physical fatigue. Such studies have clinical implications to improve the quality of life for both PCa patients on ADT as well as for male-to-female transsexuals.

Sex differences in age-related changes in the sleep-wake cycle

Age-related changes in sleep and circadian regulation occur as early as the middle years of life. Research also suggests that sleep and circadian rhythms are regulated differently between women and men. However, does sleep and circadian rhythms regulation age similarly in men and women? In this review, we present the mechanisms underlying age-related differences in sleep and the current state of knowledge on how they interact with sex. We also address how testosterone, estrogens, and progesterone fluctuations across adulthood interact with sleep and circadian regulation. Finally, we will propose research avenues to unravel the mechanisms underlying sex differences in age-related effects on sleep.

Sex differences in sleep: impact of biological sex and sex steroids

Men and women sleep differently. While much is known about the mechanisms that drive sleep, the reason for these sex differences in sleep behaviour is unknown and understudied. Historically, women and female animals are underrepresented in studies of sleep and its disorders. Nevertheless, there is a growing recognition of sex disparities in sleep and rhythm disorders. Women typically report poorer quality and more disrupted sleep across various stages of life. Findings from clinical and basic research studies strongly implicate a role for sex steroids in sleep modulation. Understanding how neuroendocrine mediators and sex differences influence sleep is central to advancing our understanding of sleep-related disorders. The investigation into sex differences and sex steroid modulation of sleep is in its infancy. Identifying the mechanisms underlying sex and gender differences in sleep will provide valuable insights leading to tailored therapeutics that benefit each sex. The goal of this review is to discuss our current understanding of how biological sex and sex steroids influence sleep behaviour from both the clinical and pre-clinical perspective.

Prolonged androgen deprivation may influence the autoregulation of estrogen receptors in the brain and pelvic floor muscles of male rats

Androgen deprivation in males has detrimental effects on various tissues and bodily functions, some of which can be restored by estradiol (E2) administration. We investigated how the duration of androgen deprivation affects the autoregulation of estrogen receptors (ERs) levels in core brain areas associated with sexual behavior and cognition, as well as in pelvic floor muscles (PFM). We also measured c-Fos levels in brain areas associated with sexual behavior shortly after the rats mated. Prolonged castration increases ERα levels in the preoptic area (POA) and E2 treatment reverses these effects. In the POA, c-Fos levels after mating are not affected by the duration of androgen deprivation and/or E2 treatment. ERβ levels in the POA as well as c-Fos levels in the POA and the core area of nucleus accumbens correlate with the mounting frequency for E2-treated Short-Term castrates. Additionally, ERβ levels in the medial amygdala are positively correlated with the mounting frequency of Long-Term castrates that received E2 treatment. In the hippocampus, ERs are downregulated only when E2 is administered early after castration, whereas downregulation of ERα in the prefrontal cortex only occurs with delayed E2 treatment. Early, but not delayed, E2 treatment after castration increases ERβ levels in the bulbocavernosus and ERα levels in the levator ani of male rats. Our data suggest that the duration of androgen deprivation may influence the autoregulation of ERs by E2 treatment in select brain areas and pelvic floor muscles of male rats.

Prolonged menstruation and increased menstrual blood with generalized δ electroencephalogram power: A case report

Estradiol changes associated with the menstrual cycle have a great impact on brain activation. δ frequency mainly appears during normal sleep status or brain injury diseases, including encephalitis and mental confusion. The current case report presents a 51-year-old female with prolonged menstruation and increased menstrual blood volume whose electroencephalogram (EEG) recording demonstrated a rare generalized 3 Hz δ frequency band in the waking status. The patient had been suffering from heart palpitations and dizziness for 6 months and was receiving treatment in the Department of Neurology (Second Xiangya Hospital). The individual had been experiencing prolonged menstruation and increased menstrual blood volume for 6 years. Gynecologial examination revealed secondary anemia and hysteromyoma. Hemoglobin levels were decreased to 69 g/l. Physical and neurological examinations, and computed tomography results appeared normal. The EEG recording indicated a generalized 3 Hz δ frequency band with 30–80 μV power and a long-range δ frequency band when the patient was hyperventilating. The prolonged menstruation and increased menstrual blood volume may have induced the generalized δ frequency without brain injury. To the best of our knowledge, this is the first formal case report of prolonged menstruation and increased menstrual blood volume with the abnormality of δ EEG power.

Gonadal steroid modulation of sleep and wakefulness in male and female rats is sexually differentiated and neonatally organized by steroid exposure

The paucity of clinical and preclinical studies investigating sex differences in sleep has resulted in mixed findings as to the exact nature of these differences. Although gonadal steroids are known to modulate sleep in females, less is known about males. Moreover, little evidence exists concerning the origin of these sex differences in sleep behavior. Thus, the goal of this study was to directly compare the sensitivity of sleep behavior in male and female Sprague Dawley rats to changes in the gonadal steroid milieu and to test whether the sex differences in sleep are the result of brain sexual differentiation or differences in circulating gonadal steroids. Here we report the magnitude of change in sleep behavior induced by either estradiol (E2) or testosterone (T) was greater in females compared with males, suggesting that sleep behavior in females is more sensitive to the suppressive effects of gonadal steroids. Furthermore, we demonstrated that the organizational effects of early gonadal steroid exposure result in male-like responsivity to gonadal steroids and directly alter the activity of the ventrolateral preoptic area (VLPO), an established sleep-promoting nucleus, in adult masculinized females. Moreover, the nonaromatizable androgen dihydrotestosterone did not suppress sleep in either males or females, suggesting that the T-mediated effect in females was due to the aromatization of T into E2. Together our data suggest that, like sex behavior, sex differences in sleep follow the classical organizational/activational effects of gonadal steroids.

Sex differences in circadian timing systems: implications for disease

Virtually every eukaryotic cell has an endogenous circadian clock and a biological sex. These cell-based clocks have been conceptualized as oscillators whose phase can be reset by internal signals such as hormones, and external cues such as light. The present review highlights the inter-relationship between circadian clocks and sex differences. In mammals, the suprachiasmatic nucleus (SCN) serves as a master clock synchronizing the phase of clocks throughout the body. Gonadal steroid receptors are expressed in almost every site that receives direct SCN input. Here we review sex differences in the circadian timing system in the hypothalamic-pituitary-gonadal axis (HPG), the hypothalamic-adrenal-pituitary (HPA) axis, and sleep-arousal systems. We also point to ways in which disruption of circadian rhythms within these systems differs in the sexes and is associated with dysfunction and disease. Understanding sex differentiated circadian timing systems can lead to improved treatment strategies for these conditions.

Sexuality and Intimacy After Definitive Treatment and Subsequent Androgen Deprivation Therapy for Prostate Cancer

There are more than 2 million prostate cancer survivors in the United States. Primary therapy with surgery or radiation results in permanent changes in sexual function. More than half of these men are subsequently treated with androgen deprivation therapy (ADT) at some point. The addition of ADT further compromises sexuality, intimacy, and a couple's relationship. This review will highlight the challenges faced by patients and couples and reveal the tremendous need for better education of physicians, patients, and couples as well as for more research in sexuality and intimacy with the goal of improving quality of life for this large population of survivors. Suggestions for clinicians to better help patients and their partners regarding sexuality and intimacy are offered.