Ruth M. Benca - US grants

The heritability of sleep patterns has been documented in both human and animal studies, although the location or mechanism of action of genes which influence sleep has not yet been determined. Narcolepsy is a disorder characterized by abnormalities of rapid eye movement (REM) sleep and is highly associated with the human leucocyte antigen (HLA) DR1/DQw1. The immune system, which is under control of the major histocompatibility complex (MHC), has also been implicated in sleep regulation. These findings suggest three key questions regarding the relationship between the MHC and sleep: 1. Is MHC expression linked to control of REM sleep and, by implication, to the symptoms of narcolepsy? 2. If such an association exists, is it causally mediated by the effects of the peripheral immune system on sleep? 3. Does MHC expression confer differential central nervous system susceptibility to the sleep regulating effects of cytokines? We propose to investigate the possible linkage between the MHC and sleep in two inbred strains of rats, Lewis (L) and Brown Norway (BN), known to have significantly different patterns of REM sleep, immune function and CNS response to the cytokine interleukin-1 (IL-1). The linkage of sleep behavior to the MHC will be studied by determining physiologic sleep patterns and susceptibility to REM sleep triggering in (LxBN) F1, (F1 x parent) F2 and recombinant inbred animals vs. parental strains. The effects of the peripheral immune system on sleep regulation will be assessed in F1 rats reconstituted with parental bone marrow, while the strain-specific effects of IL-1 will be studied in parental F1, F2 and congenic rats to determine whether IL-1 effects on sleep are modulated by MHC expression.

This is an application for an ADAMHA Research Scientist Development Award (K02). The purpose of the Award is to foster the continued scientific development of the Principal Investigator (P.I.) in understanding the psychobiology of sleep related to psychiatric disorders. Research to be performed during the period of support includes a basic study of the acute effects of light on sleep and temperature in rats. Light therapy is being used with increasing frequency to treat a variety of conditions, including depression, circadian rhythm disorders, and sleep disturbances related to aging. Although the mechanisms for light entrainment of circadian rhythms have been studied extensively, the mechanisms for acute photic effects on sleep and temperature are unknown. A better understanding of light effects on the nervous system could make light a more powerful clinical tool.

Light and dark have significant direct effects on sleep, temperature, and neuroendocrine function independent of their roles as regulators of circadian rhythms. Light therapy is being used with increasing frequency to treat a variety of conditions, including depression, circadian rhythm disorders, and sleep disturbances related to aging. Although the mechanisms for light entrainment of circadian rhythms have been studied extensively, the mechanisms for direct photic effects on sleep and temperature have not been elucidated. A better understanding of the direct effects could make light a more powerful clinical tool. We propose to study the mechanisms for direct light effects on sleep in an animal model. Light promotes sleep in both albino and pigmented rats. However, our research has shown that the effect on rapid eye-movement sleep (REM) is opposite in albino and pigmented rats. Light suppresses REM in albinos but stimulates it in pigmented rats. Albino rat show REM triggering following lights-off, whereas pigmented rats show decreases in REM during dark periods. Differences in central visual pathways have been described in albino vs. pigmented mammals. It is likely that albino and pigmented rats show differences in REM patterns in response to light because of differences in their visual systems. The existence of both behavioral and anatomic differences associated with pigmentation status provides a model for studying the mechanisms mediating the direct effects of light on sleep. The following studies are proposed to determine direct effects of light and dark on sleep induction, REM regulation, and temperature in congenic albino and pigmented rats: 1. Determination of how the direct effects of light vary with light intensity, wavelength, and duration. 2. Determination of the effect of age on the direct responses to light. 3. Investigation of the mediation of the direct effects by comparing visual pathways in albino and pigmented rats, lesioning specific visual pathways, and studying mutant strains of rats with retinal hypopigmentation.

Numerous studies have demonstrated that frontal activation patterns of the cerebral hemispheres differ during the experience of positive versus. negative emotions during waking. Furthermore, there are stable patterns of waking prefrontal activation asymmetry which are associated with temperament and pathological states such as depression. The purpose of the proposed study is to determine whether frontal activation patterns during sleep are correlated with patterns during wakefulness and/or affective content of dreaming. These studies should increase our understanding of the neural regulation of mood.

frontal lobe /cortex

Sleep deprivation has been shown to have mood-modulating effects in both normal subjects and patients with major depressive disorder, but the mechanism for these effects are unknown. Sleep deprivation also leads to sleepiness, which can impact significantly on performance, particularly in low-stimulus situations. Measurement of vigilance level could help to predict performance lapses, but currently available measures are either difficult to administer in performance settings or not highly reliable. The purposes of this study are to (1) characterize the effects of sleep deprivation on mood in normal subjects, and (2) assess the effectiveness of the startle response in measuring vigilance level. Subjects will undergo electrophysiological measures of regional brain function and emotion-modulated startle responses following a night of normal sleep and after one night of total sleep deprivation.

Light is an important regulator of behavioral state in mammals. In addition to effects on the circadian clock, changes in lighting conditions can induce immediate changes in sleep-wakefulness. For example, light increases wakefulness in humans and induces sleep in nocturnal rodents. We have used the albino rat as a model to study acute effects of light-dark shifts on sleep patterns. Albino rats show exaggerated responses to abrupt lighting changes, particularly in their rapid eye-movement (REM) sleep patterns; following lights-off, they exhibit large increases in REM sleep (REM sleep triggering), whereas lights-on suppresses REM sleep. In addition, light acutely increases non- REM (NREM) sleep and dark increases waking in both albino and pigmented rats. During the past 4 years of funding, we have characterized acute sleep-wakefulness responses to changes in light conditions and demonstrated that lesions of the superior colliculus (SC) and pretectum (PT) attenuate these responses in albino rats. We propose an integrated series of studies to further elucidate the mechanisms by which the SC-PT region regulates sleep-wakefulness in response to lighting changes: (1) Localize areas within the SC and PT which mediate REM sleep, NREM sleep and/or waking responses to light-dark shifts; (2) Describe connections between the SC-PT and brain regions known to be involved in mediating sleep and waking; (3) Use immediate early gene expression to identify brain regions which respond to acute lighting changes and correlate with behavioral responses; and (4) Determine the effects of SCN lesions on sleep-waking responses to light-dark shifts. Results from these studies should increase our understanding of how light affects the nervous system, including effects of light therapy on sleep and mood. Furthermore, we hope to elucidate the role of the SC-PT in REM sleep regulation, which may have relevance to disorders characterized by abnormalities in REM sleep, and depression

DESCRIPTION: (Adapted from the Investigator's Abstract) Stress-related sleep disorders, notably insomnia, are widely prevalent in the general population. There are few good animal models in which to study the mechanisms underlying insomnia or the sleep abnormalities associated with psychiatric disorders. Dr. Ned Kalin has been studying the role of the amygdala in emotional processing in the rhesus monkey, a relevant model for human emotion and psychopathology. In collaboration with Dr. Kalin, the Principal Investigator has obtained preliminary data from rhesus monkeys with amygdala lesions which suggest that the amygdala mediates stress effects on sleep and may be important in organizing REM/NREM sleep cycles as well. In this revised proposal, the Principal Investigator plans to study rhesus monkeys with total, bilateral lesions of the amygdala, and bilateral lesions of the central nucleus of the amygdala, the major output site from the amygdala. Using telemetry, she will compare sleep patterns under normal, unrestrained conditions and in response to a variety of stressors. These studies will establish the role of the amygdala in normal sleep organization as well as in response to emotional and physical stressors. Results obtained from these studies should increase our understanding of the mechanisms underlying sleep abnormalities in psychiatric disorders and insomnia.

DESCRIPTION (provided by applicant): Perhaps the most fundamental feature of bipolar disorder-its cycling nature-makes it one of the most difficult to model artificially in animals. Another approach is to search for naturally occurring models that already display a constellation of features of bipolar disorder, albeit in an adaptive rather than pathological manner. One such model is the white-crowned sparrow, Zonotricia leucophrys gambelii, a songbird that migrates twice a year between Alaska and California. In the spring and fall, these birds undergo a profound behavioral shift from sleeping at night (like humans) to flying at night, a behavior that reliably manifests as a marked increase in nocturnal activity in the laboratory. Our preliminary studies of these birds suggest that they show many features consistent with mania in humans, including greatly reduced sleep, changes in sleep architecture characteristic of patients with mania, increased activity, increased goal-directed activity, and endogenous seasonal cycling. We propose to establish the migratory sparrow as a model for mania with three Specific Aims: (1) Confirm that migratory activity models the sleeplessness, increased activity and seasonal cycling of mania; (2) Determine if sleep deprivation triggers or augments migratory activity, similar to sleep deprivation effects in mania; (3) Determine if mood stabilizing drugs can stop or prevent migratory sleeplessness. The migratory sparrow could provide an unparalleled opportunity to study the neurobiology and behavior of bipolar disorder, with a number of significant advantages over present models, including bipolar patients themselves. The model would have both face and predictive validity, and would allow performance of invasive studies aimed at identifying the molecular mechanisms of cycling inherent in migration and mania, as well as current and future mood stabilizing drugs.

behavioral /social science research tag; brain imaging /visualization /scanning; three dimensional imaging /topography

[unreadable] DESCRIPTION (provided by applicant): [unreadable] The current 'epidemic' of obesity has been called one of the leading public health concerns worldwide; nevertheless, all of the factors predisposing individuals to obesity have not been identified. There is now provocative evidence from clinical studies that shortened sleep duration can lead to an obese phenotype, a particularly alarming finding given that that average sleep duration has decreased by 20% over the last 50 years. [unreadable] [unreadable] To explore the physiological mechanisms underlying the link between sleep restriction and obesity, we have developed a research plan designed to study the impact of shortened sleep duration on three major neurochemical systems involved in the central control of food intake: the mediobasal hypothalamic axis (involved in translating peripheral energy balance signals into behavior), the hypothalamic-pituitary-adrenal axis (which may be involved in stress-induced preferences for energy-dense foods), and striatal opioid and dopamine systems (which mediate higher-order processes related to food motivation). We also propose a detailed analysis of sleep restriction effects on key motivational and structural components of ingestive behavior, including feeding microstructure, flavor and macronutrient preference, and food reward. A unique feature of this proposal is the novel, innovative system that will be used to precisely restrict sleep and record several components of ingestive behavior directly within the apparatus itself. In addition, we will use a novel schedule of mild sleep restriction separated by periods of recovery, a method that may have greater face and construct validity than previous paradigms used in the literature. [unreadable] [unreadable] Relevance to public health: These studs have the potential to precisely identify the neural, endocrine, and behavioral mechanisms by which sleep curtailment may lead to increased risk for obesity. To date, these factors are poorly understood, and have been previously studied using sleep deprivation schedules that do not reflect the human condition. Understanding the mechanistic link between shortened sleep and obesity may lead to novel strategies/drug targets that could help curtail the obesity epidemic, and thereby hopefully reduce rates of cardiovascular disease and type 2 diabetes. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Dozens of epidemiologic reports have linked insomnia to increased risk for suicidal ideation, suicidal behavior and suicide death in patients with major depression. The mechanism whereby insomnia increases the intensity of suicidal ideation may be mediated through dysfunctional beliefs and attitudes about sleep, somewhat similar to hopelessness. We have unpublished, preliminary data showing that the addition of the hypnotic eszopiclone to open-label fluoxetine in the treatment of depressed insomniacs is associated with a reduction in suicidal ideation, as compared with placebo added to fluoxetine. We now propose to confirm the premise that treatment of insomnia reduces suicidal ideation in a multi-site clinical trial. Wake Forest University (WFU) will be the coordinating site and a recruitment site, while Duke University (DU) and University of Wisconsin (UW) will also serve as recruiting sites. Outpatients (N=138) with major depression, insomnia, and mild- moderate suicidal ideation will be treated with open label fluoxetine for 8 weeks and will be further randomized to receive either eszopiclone or placebo at bedtime for the same period. Patients will have return office visits at 1, 2, 4, 6, and 8 weeks after treatment initiation. Assessments wll include measures of suicidal ideation intensity, overall depression severity, insomnia severity, dysfunctional cognitions about sleep, nightmare intensity, hopelessness, and actigraphy. All data will be entered in a WF-created web-based interface, and consistency of methodology across sites will be assured with regular teleconferences between sites. The sample size will be sufficient to allow 80% power to detect a 2.0 point difference in the Beck Scale for Suicide Ideation between treatment arms. Safety of participants will be assured by (1) exclusion of patients with more than severe suicidal ideation at baseline, (2) frequent follow up, (3) limited access to hypnotics, (4) access to university psychiatric inpatients units for psychiatric emergencies, (5) 24-hour per day emergency services available through the sites respective psychiatric residency programs, (6) involvement of families and loved ones, when available, in the consent process, (7) and the creation of a Data Safety Monitoring Committee that will include expertise in depression, insomnia, clinical trials, statistics, suicidology, biostatistics, ethics, and a patient advocate. The primary aim will be to assess the effect of treating insomnia with hypnotic medication on the intensity of suicidal ideation. The secondary aim will be to test whether reductions in suicidal ideation in depressed insomniacs is mediated through either reduced dysfunctional beliefs about sleep, reduced hopelessness, or through reduction in nightmares. The results of this study will inform the appropriate management of patients with mild-moderate suicidal ideation, insomnia and depression - representing an extremely common clinical scenario.

? DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is reaching epidemic proportions, and in the absence of effective treatments, prevention strategies are needed. Accumulating evidence suggests that sleep plays an important role in regulating amyloid deposition, a hallmark of AD pathology. Both sleep disturbance and obstructive sleep apnea (OSA), a disorder characterized by frequent pauses in breathing during sleep and leading to hypoxemia and sleep fragmentation, are highly prevalent in AD and are associated with progression of AD pathology. Work from our group and others has shown that sleep disruption is associated with increased amyloid deposition in preclinical AD. Our group has pioneered the use of high density EEG (hdEEG, 256 channels) to demonstrate that sleep is not uniform throughout the brain, but is locally regulated and related to plastic changes during waking; different parts of the brain fall asleep at different times, such that certain brain regions may experience chronic deficits in local sleep. Further, this phenomenon has been shown by our group to occur in a variety of neuropsychiatric disorders. Importantly, we have recently shown that OSA is associated with a local deficit in sleeping brain activity in the posterior cingulate region, in precisely the same area where peak amyloid deposition occurs in AD, suggesting a mechanism by which OSA exacerbates AD pathology. Our overarching research objective is to identify AD risk factors and mechanisms that can be modified in midlife to prevent or delay progression to AD. Sleep provides such a target. The 3 Specific Aims of this study are to determine over a 2 year period (1) the association of OSA with amyloid deposition and neural damage; (2) whether OSA treatment decreases progression of AD pathology and memory loss; and (3) the effect of local sleep deficits in the cingulate cortex on AD pathology and memory loss. The proposed study will clarify which aspects of OSA-apnea/hypopnea index, hypoxemia or sleep fragmentation-contribute to AD pathology and tests the novel hypothesis that OSA-related local sleep deprivation mediates AD progression. This study will add comprehensive imaging, sleep and activity recordings including hdEEG and amyloid-PET collection to the extensive battery of data already being collected in participants enrolled in the Wisconsin Alzheimer's Disease Research Center, comprising a cohort of asymptomatic, middle-aged subjects (50-65 yrs) at risk for AD based on parental family history. The proposed study provides an unprecedented opportunity to assess the effects of OSA, sleep features, and treatment in a well characterized and longitudinally followed group of participants at increased risk for AD. Results will also provide valuable preliminary data for a large-scale pragmatic clinical trial to test the value of OSA screening and treatment to prevent progression of AD pathology in at-risk individuals.

ABSTRACT The risk factors that contribute to cardiovascular disease originate in childhood and adolescence, track into adulthood, and have deleterious effects on long-term biopsychosocial health. Phenotypic sleep and fitness are strongly associated with mechanisms involved in the development and progression of cardiovascular disease and its risk factors (e.g., elevated body-mass index, adiposity, metabolic syndrome, elevated serum lipids, elevated blood pressure, inflammation, autonomic nervous system imbalance, poor nutrition and diet, and physical inactivity). Sleep and fitness are essential interacting physiological functions that are associated with robust metabolic, hormonal, and cognitive responses, as well as with genomic and metabolomic adaptive mechanisms. Both insufficient sleep and poor fitness are at epidemic proportions in youth and are associated with acute health threats and increased disease risk across the lifespan. However, little is known about the underlying mechanistic pathways that govern the interactions between fitness and sleep in developing youth in their modulation of cardiovascular disease risk. This proposed study aims to fill a crucial gap in the understanding how sleep and fitness interact to impact cardiovascular disease risk factors. Here we propose an ancillary study to the Molecular Transducers of Physical Activity Consortium (MoTrPAC), a multicenter NIH Common Fund project that aims to discover the molecular transducers (molecular map) responsible for the beneficial health effects of physical activity and fitness in humans across the lifespan. Adding sleep assessment to the pediatric MoTrPAC study offers a transformative opportunity to begin to elucidate the interacting mechanisms of the fitness and sleep in humans during adolescent transition, a critical period of physical, neurobiological, and psychological development. This project proposes to evaluate a cohort of children and adolescents across maturational stages who complete the MoTrPAC protocol, which includes two phases: a Cross-Sectional phase, and an Endurance Exercise Intervention phase. Of note, this ancillary study does not change the existing MoTrPAC protocol/intervention and does not include any additional interventions, and is therefore not considered a clinical trial. This study will recruit subjects from the pediatric MoTrPAC study and evaluate phenotypic measures of sleep at the end of each MoTrPAC phase. Data obtained will allow exploration of fundamental mechanistic pathways underlying fitness-sleep interactions during adolescence and guide development of future clinical trials aimed at determining optimal sleep-exercise regimens for physical and mental health in various adolescent populations, including different racial/ethnic populations and medically at-risk groups. In addition, results from this study will be added to the MoTrPAC data repository, yielding a rich and unique dataset for further exploration of genomic, metabolomic, and proteomic interactions between sleep and fitness as they impact cardiovascular disease factors.