Orexin Receptor Antagonism: Normalizing Sleep Architecture in Old Age and Disease.

Sleep is essential for human well-being, yet the quality and quantity of sleep reduce as age advances. Older persons (>65 years old) are more at risk of disorders accompanied and/or exacerbated by poor sleep. Furthermore, evidence supports a bidirectional relationship between disrupted sleep and Alzheimer's disease (AD) or related dementias. Orexin/hypocretin neuropeptides stabilize wakefulness, and several orexin receptor antagonists (ORAs) are approved for the treatment of insomnia in adults. Dysregulation of the orexin system occurs in aging and AD, positioning ORAs as advantageous for these populations. Indeed, several clinical studies indicate that ORAs are efficacious hypnotics in older persons and dementia patients and, as in adults, are generally well tolerated. ORAs are likely to be more effective when administered early in sleep/wake dysregulation to reestablish good sleep/wake-related behaviors and reduce the accumulation of dementia-associated proteinopathic substrates. Improving sleep in aging and dementia represents a tremendous opportunity to benefit patients, caregivers, and health systems.

International Union of Basic and Clinical Pharmacology CXIV: Orexin Receptor Function, Nomenclature and Pharmacology.

The orexin system consists of the peptide transmitters orexin-A and -B and the G protein-coupled orexin receptors OX1 and OX2 Orexin receptors are capable of coupling to all four families of heterotrimeric G proteins, and there are also other complex features of the orexin receptor signaling. The system was discovered 25 years ago and was immediately identified as a central regulator of sleep and wakefulness; this is exemplified by the symptomatology of the disorder narcolepsy with cataplexy, in which orexinergic neurons degenerate. Subsequent translation of these findings into drug discovery and development has resulted to date in three clinically used orexin receptor antagonists to treat insomnia. In addition to sleep and wakefulness, the orexin system appears to be a central player at least in addiction and reward, and has a role in depression, anxiety and pain gating. Additional antagonists and agonists are in development to treat, for instance, insomnia, narcolepsy with or without cataplexy and other disorders with excessive daytime sleepiness, depression with insomnia, anxiety, schizophrenia, as well as eating and substance use disorders. The orexin system has thus proved an important regulator of numerous neural functions and a valuable drug target. Orexin prepro-peptide and orexin receptors are also expressed outside the central nervous system, but their potential physiological role there remains unknown. Significance Statement The orexin system was discovered 25 years ago and immediately emerged as an essential sleep-wakefulness regulator. This discovery has tremendously increased the understanding of these processes and has thus far resulted in the market approval of three orexin receptor antagonists, which promote more physiological sleep than previous hypnotics. Further, orexin receptor agonists and antagonists with different pharmacodynamic properties are in development since research has revealed additional potential therapeutic indications. Orexin receptor signaling is complex and may represent novel features.

Default Mode Network Modulation by Psychedelics: A Systematic Review.

Psychedelics are a unique class of drug that commonly produce vivid hallucinations as well as profound psychological and mystical experiences. A grouping of interconnected brain regions characterized by increased temporal coherence at rest have been termed the Default Mode Network (DMN). The DMN has been the focus of numerous studies assessing its role in self-referencing, mind wandering, and autobiographical memories. Altered connectivity in the DMN has been associated with a range of neuropsychiatric conditions such as depression, anxiety, post-traumatic stress disorder, attention deficit hyperactive disorder, schizophrenia, and obsessive-compulsive disorder. To date, several studies have investigated how psychedelics modulate this network, but no comprehensive review, to our knowledge, has critically evaluated how major classical psychedelic agents-lysergic acid diethylamide, psilocybin, and ayahuasca-modulate the DMN. Here we present a systematic review of the knowledge base. Across psychedelics there is consistent acute disruption in resting state connectivity within the DMN and increased functional connectivity between canonical resting-state networks. Various models have been proposed to explain the cognitive mechanisms of psychedelics, and in one model DMN modulation is a central axiom. Although the DMN is consistently implicated in psychedelic studies, it is unclear how central the DMN is to the therapeutic potential of classical psychedelic agents. This article aims to provide the field with a comprehensive overview that can propel future research in such a way as to elucidate the neurocognitive mechanisms of psychedelics.

Hypocretins (orexins): The ultimate translational neuropeptides.

The hypocretins (Hcrts), also known as orexins, are two neuropeptides produced exclusively in the lateral hypothalamus. They act on two specific receptors that are widely distributed across the brain and involved in a myriad of neurophysiological functions that include sleep, arousal, feeding, reward, fear, anxiety and cognition. Hcrt cell loss in humans leads to narcolepsy with cataplexy (narcolepsy type 1), a disorder characterized by intrusions of sleep into wakefulness, demonstrating that the Hcrt system is nonredundant and essential for sleep/wake stability. The causal link between Hcrts and arousal/wakefulness stabilisation has led to the development of a new class of drugs, Hcrt receptor antagonists to treat insomnia, based on the assumption that blocking orexin-induced arousal will facilitate sleep. This has been clinically validated: currently, two Hcrt receptor antagonists are approved to treat insomnia (suvorexant and lemborexant), with a New Drug Application recently submitted to the US Food and Drug Administration for a third drug (daridorexant). Other therapeutic applications under investigation include reduction of cravings in substance-use disorders and prevention of neurodegenerative disorders such as Alzheimer's disease, given the apparent bidirectional relationship between poor sleep and worsening of the disease. Circuit neuroscience findings suggest that the Hcrt system is a hub that integrates diverse inputs modulating arousal (e.g., circadian rhythms, metabolic status, positive and negative emotions) and conveys this information to multiple output regions. This neuronal architecture explains the wealth of physiological functions associated with Hcrts and highlights the potential of the Hcrt system as a therapeutic target for a number of disorders. We discuss present and future possible applications of drugs targeting the Hcrt system for the treatment of circuit-related neuropsychiatric and neurodegenerative conditions.

Characterizing persistent urinary incontinence after successful fistula closure: the Uganda experience.

BACKGROUND: Obstetric fistula is a devastating childbirth injury. Despite successful closure of the fistula, 16% to 55% of women suffer from persistent urinary incontinence after surgery. OBJECTIVE: This study assessed the type and severity of persistent incontinence after successful fistula closure and its impact on the quality of life of Ugandan women post-fistula treatment. STUDY DESIGN: This cross-sectional study enrolled women with a history of obstetric fistula repair who continued to have persistent urinary incontinence (cases, N=36) and women without incontinence (controls, N=52) after successful fistula closure. Data were collected in central and eastern Uganda between 2017 and 2019. All the participants completed a semistructured questionnaire. Cases underwent a clinical evaluation and a 2-hour pad test and completed a series of incontinence questionnaires, including two novel tools designed to assess the severity of incontinence in low-literacy populations. RESULTS: Cases were more likely to have acquired a fistula during their first delivery (63% vs 37%, P=.02), were younger when they developed a fistula (20.3±5.8 vs 24.8±7.5 years old, P=.003), and were more likely to have had >2 fistula surgeries (67% vs 2%, P≤.001). Cases reported a much higher rate of planned home birth for their index pregnancy compared to controls (44% vs 11%), though only 14% of cases and 12% of controls actually delivered at home. Cases reported higher rates of pain with intercourse (36% vs 18%, P=.05), but recent sexual activity status (intercourse within the previous six months) was not significantly different between the groups (47% vs 62%, P=.18). Among cases, 67% reported stress incontinence, 47% reported urgency incontinence, and 47% reported mixed incontinence. The cough stress test was successfully done with 92% of the cases, and of these, almost all (97%) had a positive cough stress test. More than half (53%) rated their incontinence as "very severe," which was consistent with objective findings. The 24-hour voiding diary indicated both high urinary frequency (average 14) and very frequent leakage episodes (average 20). Two-hour pad-tests indicated that 86% of cases had >4 g change in pad weight within 2 hours. Women with more severe incontinence reported a more negative impact on their quality of life. The mean score of the International Consultation on Incontinence Questionnaire-Quality of Life was 62.77±12.76 (range, 28-76, median=67), with a higher score indicating a greater impact on the quality of life. There was also a high mental health burden, with both cases and controls reporting high rates of suicidal ideation at any point since developing fistula (36% vs 31%, P=.67). CONCLUSION: Women with obstetric fistulas continue to suffer from severe persistent urinary incontinence even after successful fistula closure. Both stress and urgency incontinence are highly prevalent in this population. Worsening severity of incontinence is associated with a greater negative impact on the quality of life.

Selective NaV1.1 activation rescues Dravet syndrome mice from seizures and premature death.

Dravet syndrome is a catastrophic, pharmacoresistant epileptic encephalopathy. Disease onset occurs in the first year of life, followed by developmental delay with cognitive and behavioral dysfunction and substantially elevated risk of premature death. The majority of affected individuals harbor a loss-of-function mutation in one allele of SCN1A, which encodes the voltage-gated sodium channel NaV1.1. Brain NaV1.1 is primarily localized to fast-spiking inhibitory interneurons; thus the mechanism of epileptogenesis in Dravet syndrome is hypothesized to be reduced inhibitory neurotransmission leading to brain hyperexcitability. We show that selective activation of NaV1.1 by venom peptide Hm1a restores the function of inhibitory interneurons from Dravet syndrome mice without affecting the firing of excitatory neurons. Intracerebroventricular infusion of Hm1a rescues Dravet syndrome mice from seizures and premature death. This precision medicine approach, which specifically targets the molecular deficit in Dravet syndrome, presents an opportunity for treatment of this intractable epilepsy.

Novel alterations in corneal neuroimmune phenotypes in mice with central nervous system tauopathy.

BACKGROUND: Tauopathy in the central nervous system (CNS) is a histopathological hallmark of frontotemporal dementia (FTD) and Alzheimer's disease (AD). Although AD is accompanied by various ocular changes, the effects of tauopathy on the integrity of the cornea, which is densely innervated by the peripheral nervous system and is populated by resident dendritic cells, is still unknown. The aim of this study was to investigate if neuroimmune interactions in the cornea are affected by CNS tauopathy. METHODS: Corneas from wild type (WT) and transgenic rTg4510 mice that express the P301L tau mutation were examined at 2, 6, 8, and 11 months. Clinical assessment of the anterior segment of the eye was performed using spectral domain optical coherence tomography. The density of the corneal epithelial sensory nerves and the number and field area of resident epithelial dendritic cells were assessed using immunofluorescence. The immunological activation state of corneal and splenic dendritic cells was examined using flow cytometry and compared between the two genotypes at 9 months of age. RESULTS: Compared to age-matched WT mice, rTg4510 mice had a significantly lower density of corneal nerve axons at both 8 and 11 months of age. Corneal nerves in rTg4510 mice also displayed a higher percentage of beaded nerve axons and a lower density of epithelial dendritic cells compared to WT mice. From 6 months of age, the size of the corneal dendritic cells was significantly smaller in rTg4510 compared to WT mice. Phenotypic characterization by flow cytometry demonstrated an activated state of dendritic cells (CD86+ and CD45+ CD11b+CD11c+) in the corneas of rTg4510 compared to WT mice, with no distinct changes in the spleen monocytes/dendritic cells. At 2 months of age, there were no significant differences in the neural or immune structures between the two genotypes. CONCLUSIONS: Corneal sensory nerves and epithelial dendritic cells were altered in the rTg4510 mouse model of tauopathy, with temporal changes observed with aging. The activation of corneal dendritic cells prior to the gradual loss of neighboring sensory nerves suggests an early involvement of corneal immune cells in tau-associated pathology originating in the CNS.

Hypnotics with novel modes of action.

Insomnia and, more generally, lack of sleep are on the rise. Traditionally treated by classical hypnotics, such as benzodiazepines and Z drugs, which both act on the GABAA receptor, and other modalities, including nondrug therapies, such as cognitive behavioural therapy, there is a range of new hypnotics which are being developed or have recently received market approval. Suvorexant and the like target the orexin/hypocretin system: they should have less side effects in terms of drug-drug interactions with e.g. alcohol, less memory impairment and dependence potential compared to classical hypnotics.

Capacity building in female pelvic medicine and reconstructive surgery: Global Health Partnership beyond fistula care in Ethiopia.

OBJECTIVE: Obstetric fistula is a devastating childbirth injury that leaves women incontinent, stigmatized and often isolated from their families and communities. In Ethiopia, although much attention has focused on treating and preventing obstetric fistula, other more prevalent childbirth-related pelvic floor disorders, such as pelvic organ prolapse, non-fistula-related incontinence and post-fistula residual incontinence, remain largely unattended. The lack of international and local attention to addressing devastating pelvic floor disorders is concerning for women in low- and middle-income countries. The objective of this article is to highlight the need for a more comprehsive approach to pelvic floor care and to share our experience in addressing it. METHODS: Here, we share our experience launching one of the first formal training programs in Female Pelvic Medicine and Reconstructive Surgery (FPMRS) in Ethiopia. RESULTS: This fellowship program provides quality care while strengthening the health system in its local context. This program has positioned Ethiopia to be a regional leader by providing comprehensive training of surgeons and allied health professionals, building appropriate health system and research infrastructure, and developing a formal FPMRS training curriculum. CONCLUSION: We hope that sharing this experience will serve as a template for others championing comprehensive pelvic floor care for women in low- and middle-income countries.

Characteristics of persistent urinary incontinence after successful fistula closure in Ethiopian women.

INTRODUCTION AND HYPOTHESIS: Obstetric fistulas have devastating consequences for women. Although surgical repair is largely successful in closing the defect, many women with successful fistula closure report persistent urinary incontinence. Our study is aimed at characterizing incontinence after successful fistula repair and its impact on quality of life. METHODS: This cross-sectional study enrolled women with a history of successful obstetric fistula closure with (n = 51; cases) or without (n = 50; controls) persistent urinary incontinence. Data were collected in Mekelle, Ethiopia, between 2016 and 2018. All cases underwent clinical evaluation and completed questionnaires characterizing the type, severity, and impact of incontinence. RESULTS: Cases were significantly more likely to have acquired their fistula at an earlier age and with their first vaginal delivery compared with controls. Almost all cases reported both stress (98%) and urgency (94%) incontinence, and half reported constant urinary leakage (49%) despite successful fistula closure. Of cases who completed urodynamic evaluation (n = 22), all had genuine stress incontinence and none had detrusor overactivity. All cases reported moderate to severe (80.4%) or very severe (19.6%) incontinence (measured by ICIQ-SF) and this had a moderate to severe negative impact on their quality of life (as measured by ICIQ-QoL). Although history of suicidal ideation was not significantly different between the groups, among those with suicidal ideation, cases were more likely to report having made a plan and/or attempted to commit suicide. CONCLUSIONS: When urinary incontinence persists after successful fistula closure, it tends to be severe and of mixed etiology and has a significant negative impact on quality of life and mental health.

Discovery of amino-1,4-oxazines as potent BACE-1 inhibitors.

New amino-1,4-oxazine derived BACE-1 inhibitors were explored and various synthetic routes developed. The binding mode of the inhibitors was elucidated by co-crystallization of 4 with BACE-1 and X-ray analysis. Subsequent optimization led to inhibitors with low double digit nanomolar activity in a biochemical and single digit nanomolar potency in a cellular assays. To assess the inhibitors for their permeation properties and potential to cross the blood-brain-barrier a MDR1-MDCK cell model was successfully applied. Compound 8a confirmed the in vitro results by dose-dependently reducing Aß levels in mice in an acute treatment regimen.

Innovations in Population Health Surveillance: Using Electronic Health Records for Chronic Disease Surveillance.

With 87% of providers using electronic health records (EHRs) in the United States, EHRs have the potential to contribute to population health surveillance efforts. However, little is known about using EHR data outside syndromic surveillance and quality improvement. We created an EHR-based population health surveillance system called the New York City (NYC) Macroscope and assessed the validity of diabetes, hyperlipidemia, hypertension, smoking, obesity, depression, and influenza vaccination indicators. The NYC Macroscope uses aggregate data from a network of outpatient practices. We compared 2013 NYC Macroscope prevalence estimates with those from a population-based, in-person examination survey, the 2013-2014 NYC Health and Nutrition Examination Survey. NYC Macroscope diabetes, hypertension, smoking, and obesity prevalence indicators performed well, but depression and influenza vaccination estimates were substantially lower than were survey estimates. Ongoing validation will be important to monitor changes in validity over time as EHR networks mature and to assess new indicators. We discuss NYC's experience and how this project fits into the national context. Sharing lessons learned can help achieve the full potential of EHRs for population health surveillance.

Discovery of 1H-pyrazolo[3,4-b]pyridines as potent dual orexin receptor antagonists (DORAs).

Compound rac-1 was identified by high throughput screening. Here we report SAR studies and MedChem optimization towards the highly potent dual orexin receptor antagonists (S)-2 and (S)-3. Furthermore, strategies to overcome the suboptimal physicochemical properties are highlighted and the pharmacokinetic profiles of representative compounds is presented.

Enhanced proteolytic clearance of plasma Aß by peripherally administered neprilysin does not result in reduced levels of brain Aß in mice.

Accumulation of ß-amyloid (Aß) in the brain is believed to contribute to the pathology of Alzheimer's Disease (AD). Aß levels are controlled by the production of Aß from amyloid precursor protein, degradation by proteases, and peripheral clearance. In this study we sought to determine whether enhancing clearance of plasma Aß with a peripherally administered Aß-degrading protease would reduce brain Aß levels through a peripheral sink. Neprilysin (NEP) is a zinc-dependent metalloprotease that is one of the key Aß-degrading enzymes in the brain. We developed a NEP fusion protein with in vitro degradation of Aß and a 10 day plasma half-life in mouse. Intravenous administration of NEP to wild-type and APP23 transgenic mice resulted in dose-dependent clearance of plasma Aß. However, this did not correspond to reduced levels of soluble brain Aß with treatment up to 5 weeks in WT mice or formic acid-extractable brain Aß with 3 month treatment in aged APP23. In contrast, intracranial injection of NEP resulted in an acute decrease in soluble brain Aß. We found no change in amyloid precursor protein gene expression in mice treated with intravenous NEP, suggesting that the lack of effects in the brain following this route of administration was not caused by compensatory upregulation of Aß production. Taken together, these results suggest a lack of a robust peripheral Aß efflux sink through which brain amyloid burdens can be therapeutically reduced.

Assessing capacity and disease burden in a virtual network of New York City primary care providers following Hurricane Sandy.

Urban contexts introduce unique challenges that must be addressed to ensure that areas of high population density can function when disasters occur. The ability to generate useful data to guide decision-making is critical in this context. Widespread adoption of electronic health record (EHR) systems in recent years has created electronic data sources and networks that may play an important role in public health surveillance efforts, including in post-disaster situations. The Primary Care Information Project (PCIP) at the New York City Department of Health and Mental Hygiene has partnered with local clinicians to establish an electronic data system, and this network provides infrastructure to support primary care surveillance activities in New York City. After Hurricane Sandy, PCIP generated several sets of data to contribute to the city's efforts to assess the impact of the storm, including daily connectivity data to establish practice operations, data to examine patterns of primary care utilization in severely affected and less affected areas, and data on the frequency of respiratory infection diagnosis in the primary care setting. Daily patient visit data from three heavily affected neighborhoods showed the health department where primary care capacity was most affected in the weeks following Sandy. Overall transmission data showed that practices in less affected areas were quicker to return to normal reporting patterns, while those in more affected areas did not resume normal data transmissions for a few months. Rates of bronchitis increased after Sandy compared to the two prior years; while this was most likely attributable to a more severe flu season, it demonstrates the capacity of primary care networks to pick up on these types of post-emergency trends. Hurricane Sandy was the first disaster situation where PCIP was asked to assess public health impact, generating information that could contribute to aid and recovery efforts. This experience allowed us to explore the strengths and weaknesses of ambulatory EHR data in post-disaster settings. Data from ambulatory EHR networks can augment existing surveillance streams by providing sentinel population snapshots on clinically available indicators in near real time.

Client-reported quality of facility-managed medication abortion compared with pharmacy-sourced self-managed abortion in Bangladesh.

OBJECTIVE: We used the newly developed Abortion Care Quality Tool (ACQTool) to compare client-reported quality of medication abortion care by source (facility-managed vs pharmacy-sourced self-managed abortion (SMA)) in Bangladesh. METHODS: We leveraged exit and 30-day follow-up surveys collected to develop and validate the ACQTool collected at nongovernmental organisation (NGO)-supported or -operated facilities in the public and private sector and pharmacies from three districts in Bangladesh. We used bivariate statistics to compare 18 client-reported quality indicators grouped in six domains and eight abortion outcomes, by source (facility vs pharmacy). We used multivariable logistic regression to identify factors associated with selected quality indicators and outcomes (abortion affordability, information provision, and knowing what to do for an adverse event), controlling for client sociodemographic characteristics. RESULTS: Of 550 abortion clients, 146 (26.5%) received a facility-managed medication abortion and 404 (73.5%) had a pharmacy-sourced SMA. Clients reported higher quality in facilities for five indicators, and higher in pharmacies for two indicators; the remaining 11 indicators were not different by source. Compared with facility-based clients, pharmacy clients had higher odds of reporting that the cost of abortion was affordable (adjusted odds ratio (aOR) 3.55; 95% CI 2.27 to 5.58) but lower odds of reporting high information provision (aOR 0.14; 95% CI 0.09 to 0.23). Seven of eight abortion outcomes showed no differences; pharmacy clients had lower odds of knowing what to do if an adverse event occurred (aOR 0.45; 95% CI 0.23 to 0.82). CONCLUSIONS: In Bangladesh, there is no difference in client-reported quality of medication abortion care between health facilities and pharmacies for the majority of quality and outcome indicators. However, information provision and preparedness were higher quality at facilities, while pharmacies were more affordable.

Hypocretin-1 receptor antagonism improves inhibitory control during the Go/No-Go task in highly motivated, impulsive male mice.

RATIONALE: Motivation and inhibitory control are dominantly regulated by the dopaminergic (DA) and noradrenergic (NA) systems, respectively. Hypothalamic hypocretin (orexin) neurons provide afferent inputs to DA and NA nuclei and hypocretin-1 receptors (HcrtR1) are implicated in reward and addiction. However, the role of the HcrtR1 in inhibitory control is not well understood. OBJECTIVES: To determine the effects of HcrtR1 antagonism and motivational state in inhibitory control using the go/no-go task in mice. METHODS: n = 23 male C57Bl/6JArc mice were trained in a go/no-go task. Decision tree dendrogram analysis of training data identified more and less impulsive clusters of animals. A HcrtR1 antagonist (BI001, 12.5 mg/kg, per os) or vehicle were then administered 30 min before go/no-go testing, once daily for 5 days, under high (food-restricted) and low (free-feeding) motivational states in a latin-square crossover design. Compound exposure levels were assessed in a satellite group of animals. RESULTS: HcrtR1 antagonism increased go accuracy and decreased no-go accuracy in free-feeding animals overall, whereas it decreased go accuracy and increased no-go accuracy only in more impulsive, food restricted mice. HcrtR1 antagonism also showed differential effects in premature responding, which was increased in response to the antagonist in free-feeding, less impulsive animals, and decreased in food restricted, more impulsive animals. HcrtR1 receptor occupancy by BI001 was estimated at ~ 66% during the task. CONCLUSIONS: These data indicate that hypocretin signalling plays roles in goal-directed behaviour and inhibitory control in a motivational state-dependant manner. While likely not useful in all settings, HcrtR1 antagonism may be beneficial in improving inhibitory control in impulsive subpopulations.

Evidence to support health system prioritization of health behaviors in the COVID-19 era.

BACKGROUND: Since the COVID-19 pandemic health systems have shifted necessarily from chronic to infectious disease treatment, but chronic disease remains critical. One large health system uniquely tracks member health behaviors. This analysis compares data from select months of an ongoing monthly cross-sectional survey before and during the pandemic. METHODS: Responses in April 2019 (pre-pandemic), April 2020 (early pandemic) or April 2021 (later pandemic) were included in the primary analysis (N = 252). Differences in meeting health behavior guidelines were analyzed via logistic regression. RESULTS: A significant decline was seen for physical activity (19% not meeting guidelines pre-pandemic vs. 41% later pandemic) but not fruit/vegetable, alcohol, or sleep from early to later pandemic. Prevalence of women not meeting tobacco guidelines increased from early (5%) to later pandemic (10%) while prevalence in men decreased (10% vs 4% respectively). The percent of people not thinking about the good things that happen to them fluctuated closely with reports of new COVID-19 cases. CONCLUSIONS: Findings show the nuance of changing health behaviors throughout the pandemic. Results should be used by health systems to tailor support based on insights from the pandemic experience.

Orexin 2 receptor antagonism sex-dependently improves sleep/wakefulness and cognitive performance in tau transgenic mice.

BACKGROUND AND PURPOSE: Tau pathology contributes to a bidirectional relationship between sleep disruption and neurodegenerative disease. Tau transgenic rTg4510 mice model tauopathy symptoms, including sleep/wake disturbances, which manifest as marked hyperarousal. This phenotype can be prevented by early transgene suppression; however, whether hyperarousal can be rescued after onset is unknown. EXPERIMENTAL APPROACH: Three 8-week experiments were conducted with wild-type and rTg4510 mice after age of onset of hyperarousal (4.5 months): (1) Tau transgene suppression with doxycycline (200 ppm); (2) inactive phase rapid eye movement (REM) sleep enhancement with the dual orexin receptor antagonist suvorexant (50 mg·kg-1 ·day-1 ); or (3) Active phase non-NREM (NREM) and REM sleep enhancement using the selective orexin 2 (OX2 ) receptor antagonist MK-1064 (40 mg·kg-1 ·day-1 ). Sleep was assessed using polysomnography, cognition using the Barnes maze, and tau pathology using immunoblotting and/or immunohistochemistry. KEY RESULTS: Tau transgene suppression improved tauopathy and hippocampal-dependent spatial memory, but did not modify hyperarousal. Pharmacological rescue of REM sleep deficits did not improve spatial memory or tau pathology. In contrast, normalising hyperarousal by increasing both NREM and REM sleep via OX2 receptor antagonism restored spatial memory, independently of tauopathy, but only in male rTg4510 mice. OX2 receptor antagonism induced only short-lived hypnotic responses in female rTg4510 mice and did not improve spatial memory, indicating a tau- and sex-dependent disruption of OX2 receptor signalling. CONCLUSIONS AND IMPLICATIONS: Pharmacologically reducing hyperarousal corrects tau-induced sleep/wake and cognitive deficits. Tauopathy causes sex-dependent disruptions of OX2 receptor signalling/function, which may have implications for choice of hypnotic therapeutics in tauopathies.

Discovery of cyclic sulfoxide hydroxyethylamines as potent and selective ß-site APP-cleaving enzyme 1 (BACE1) inhibitors: structure based design and in vivo reduction of amyloid ß-peptides.

Previous structure based optimization in our laboratories led to the identification of a novel, high-affinity cyclic sulfone hydroxyethylamine-derived inhibitor such as 1 that lowers CNS-derived Aß following oral administration to transgenic APP51/16 mice. Herein we report SAR development in the S3 and S2' subsites of BACE1 for cyclic sulfoxide hydroxyethyl amine inhibitors, the synthetic approaches employed in this effort, and in vivo data for optimized compound such as 11d.