Randy J. Nelson - US grants

The general goal of the proposed studies is to develop a comprehensive model of the regulation of seasonal breeding in mammals. More specifically, I seek to identify more precisely the external cues that act alone or in concert with photoperiod to regulate seasonal breeding in male deer mice and house mice. A number of factorial experiments are proposed to study the interactive effects of four environmental factors (photoperiod, temperature, food and water availability) on reproductive neuroendocrinology. Previous studies on the control of rodent seasonal breeding have primarily focused upon the role of photoperiod (day length) influences upon breeding in animals maintained in mild laboratory temperatures with ad libitum access to food and water. However, a substantial proportion of deer mice and all house mice fail to respond to inhibitory photoperiods; these animals display seasonal breeding patterns in the field. Data from other agricultural pest species (e.g., Microtus ochrogaster, M. pinetorum) support the contention that day length cues may be unimportant in the regulation of seasonal reproduction in small opportunistic breeders. Some individual deer mice inhibit reproduction when ambient temperatures are low, whereas other mice are affected only if food intake is reduced. The proposed studies will provide data to construct a hierarchy of regulatory extrinsic cues. These studies will provide new conceptual perspectives of seasonally breeding rodents. The use of feral mice, rather than highly inbred species and the manipulation of several environmental factors instead of the traditional one or two, should allow new, ecologically relevant statements regarding the control of seasonal reproduction.

The general goal of the proposed studies is to develop a comprehensive model of the regulation of seasonal breeding in mammals. More specifically, I seek to identify more precisely the external cues that act alone or in concert with photoperiod to regulate seasonal breeding in male deer mice and house mice. A number of factorial experiments are proposed to study the interactive effects of four environmental factors (photoperiod, temperature, food and water availability) on reproductive neuroendocrinology. Previous studies on the control of rodent seasonal breeding have primarily focused upon the role of photoperiod (day length) influences upon breeding in animals maintained in mild laboratory temperatures with ad libitum access to food and water. However, a substantial proportion of deer mice and all house mice fail to respond to inhibitory photoperiods; these animals display seasonal breeding patterns in the field. Data from other agricultural pest species (e.g., Microtus ochrogaster, M. pinetorum) support the contention that day length cues may be unimportant in the regulation of seasonal reproduction in small opportunistic breeders. Some individual deer mice inhibit reproduction when ambient temperatures are low, whereas other mice are affected only if food intake is reduced. The proposed studies will provide data to construct a hierarchy of regulatory extrinsic cues. These studies will provide new conceptual perspectives of seasonally breeding rodents. The use of feral mice, rather than highly inbred species and the manipulation of several environmental factors instead of the traditional one or two, should allow new, ecologically relevant statements regarding the control of seasonal reproduction.

This is a Shannon Award providing partial support for research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. Further scientific data for the CRISP System are unavailable at this time.

The general goal of the proposed studies is to develop a more comprehensive model of the regulation of seasonal breeding in rodents. More specifically, the goals of this proposal are two-fold: (1) to identity more precisely the external cues that act alone or in concert with photoperiod to regulate seasonal breeding male deer mice and prairie voles, and (2) to ascertain the relative costs and benefits of seasonal reproductive quiescence. A number of factorial experiments are proposed to study the interactive effects of four environmental factors (photoperiod, temperature, food quality, and food quantity) on reproductive function. Previous studies on the control of rodent seasonal breeding have primarily focused upon the role of photoperiod (day length) influences upon breeding in animals maintained in mild laboratory ambient temperatures with ad libitum access to food and water. However, a substantial minority of deer mice and prairie voles fail to respond to inhibitory photoperiods; these animals display seasonal breeding patterns in the field. Data from these and other agricultural pest species (e.g., Microtus ochrogaster, M. pinetorum) support the contention that day length cues may be insufficient or of minimal significance in the regulation of seasonal reproduction in small, opportunistic breeders. Some individual deer mice inhibit reproduction when ambient temperatures are low, whereas other mice are affected only if food intake is reduced. Winter breeding rodents would appear to have an advantage over reproductively quiescent animals in terms of possible breeding successes. There must be costs to maintaining the reproductive system during the winter. Several experiments are proposed to evaluate the costs and benefits of winter reproduction in small rodents. The effects of extrinsic and social factors on metabolic rates and thermoregulatory behavior will be assessed. The proposed studies will provide data to understand more completely the hierarchy of regulatory extrinsic cues. These studies will provide new conceptual perspectives of seasonally breeding rodents. The use of naturally selected populations of rodents, rather than highly inbred species and the manipulation of several environmental factors, instead of the traditional one or two, should allow new, ecologically relevant statements about the control of seasonal reproduction.

The general goal of the proposed studies is to develop a more comprehensive model of the regulation of seasonal breeding in rodents. More specifically, the goals of this proposal are two-fold: (1) to identity more precisely the external cues that act alone or in concert with photoperiod to regulate seasonal breeding male deer mice and prairie voles, and (2) to ascertain the relative costs and benefits of seasonal reproductive quiescence. A number of factorial experiments are proposed to study the interactive effects of four environmental factors (photoperiod, temperature, food quality, and food quantity) on reproductive function. Previous studies on the control of rodent seasonal breeding have primarily focused upon the role of photoperiod (day length) influences upon breeding in animals maintained in mild laboratory ambient temperatures with ad libitum access to food and water. However, a substantial minority of deer mice and prairie voles fail to respond to inhibitory photoperiods; these animals display seasonal breeding patterns in the field. Data from these and other agricultural pest species (e.g., Microtus ochrogaster, M. pinetorum) support the contention that day length cues may be insufficient or of minimal significance in the regulation of seasonal reproduction in small, opportunistic breeders. Some individual deer mice inhibit reproduction when ambient temperatures are low, whereas other mice are affected only if food intake is reduced. Winter breeding rodents would appear to have an advantage over reproductively quiescent animals in terms of possible breeding successes. There must be costs to maintaining the reproductive system during the winter. Several experiments are proposed to evaluate the costs and benefits of winter reproduction in small rodents. The effects of extrinsic and social factors on metabolic rates and thermoregulatory behavior will be assessed. The proposed studies will provide data to understand more completely the hierarchy of regulatory extrinsic cues. These studies will provide new conceptual perspectives of seasonally breeding rodents. The use of naturally selected populations of rodents, rather than highly inbred species and the manipulation of several environmental factors, instead of the traditional one or two, should allow new, ecologically relevant statements about the control of seasonal reproduction.

DESCRIPTION (Adapted from the Investigator's Abstract): The long-term goal of this research is to understand how somatosensory information is processed dynamically during purposeful hand movements. The experiments are designed to demonstrate when, and under what behavioral conditions, the responsiveness of primate sensorimotor cortical neurons is altered. This work is also designed to determine what behavioral consequences result from these alterations. Through neurophysiological experiments, we will determine how sensory responses and movement-related activity is altered during three types of behaviors that mimic those used everyday. The first is designed to show how sensory responsiveness changes immediately following an unpredictable outcome of a previous movement. The second will show how responsiveness changes when somatosensory inputs are needed to guide movements as compared with guidance by explicit visual cues. The third will determine if somatosensory signals can be detected at times before movements when sensory gating is thought to occur, and if this detection depends on the modality of stimuli previously used to trigger movements. Each experiment will determine the conditions under which the activity of sensorimotor cortical neurons is more tightly coupled to sensory stimuli and movement kinematics. The hypotheses to be tested are: (1) That the responsiveness of sensorimotor cortical neurons is attenuated when behavioral conditions are predictable. (2) That facilitation and suppression of responsiveness occur when peripheral and central inputs are crucial for the initiation and execution of movements, and that these modulations are regionally-specific. (3) That overly-trained movements can be altered only up to a certain point before their onset, and that this phenomenon reflects transient sensory gating which can be seen in the activity of sensorimotor cortical neurons. The underlying hypothesis is that external sensory information is utilized more when there has been a mismatch between actual and predicted behavioral outcome. These hypotheses will be tested, using single electrodes and multi-electrode arrays to record extracellular activity in the primary somatosensory, parietal (area 5), primary motor and premotor (PMd) cortices of awake, behaving monkeys trained to perform wrist movement tasks. Coupling of activity to sensory stimuli will be assessed by mean vector analyses. Movement kinematics will be correlated with neuronal activity using multiple regression analyses. The three behaviors to be studied are similar to those used during retraining when sensory disorders occur following stroke, traumatic head injury, peripheral neuropathy and movement disorders. By understanding how and where somatosensory responsiveness is modified during behavior, deficits can be more readily assessed and localized.

The general objective of this Core is to provide a facility behavioral effects of genetic, pharmacological, and surgical manipulations in mice and rats tat are recovering from stroke or cardiac arrest/CPR. Behavioral examination is an integral part of the post-ischemic recovery period and is correlated with physiological data and histological end-points for each animal. This is a novel approach in the field of experimental cerebral ischemia and cardiac arrest/CPR because long term behavioral outcomes are rarely examined. Most work has emphasized histological and morphological measures of injury (or recovery). Further, in some cases, behavioral changes may be the most salient phenotypic expression observed among mutant mice. In Aims 1 and 2, the behavioral consequences of sigma- receptor activation are assessed in normal and post-ischemic rats and in PPBP treated mice, as well as mice genetically deficient in neuronal nitric oxide synthase. In Aims 3 and 4, we will determine if neurobehavioral outcomes after experimental stroke are more favorable in female versus male rats and if stroke injury is exacerbated in transgenic mice deficient in estrogen receptors (estrogen receptor knock-outs). Lastly, cognitive dysfunction after cardiac arrest/CPR is evaluated in Aim 5 and 3 transgenic mouse strains as a function of neuronal cytotoxicity. The Neurobehavioral Core will utilize the animals obtained from each project to gain new insight into the functional vulnerability of specific brain regions to ischemic injury and the potential for plasticity in recovery of sensory motor function, memory, and simple cognitive tasks.

DESCRIPTION (applicant's abstract): Uncontrolled aggressive behavior is a serious social problem. Several rodent models of aggression have been developed to understand the neurobiological bases of aggression with the goal of developing pharmacological interventions. One common feature of these rodent models of aggression is that brain serotonin concentrations tend to be inversely correlated with aggressive behavior. A new model of intense, unrelenting aggression has been developed using mice that have the gene encoding the neuronal isoform of nitric oxide synthase (nNOS) selectively deleted. Male nNOS-/- mice display persistent aggression against other males, and persistent mounting attempts toward wild-type (WT) anestrous females. Female nNOS-/- mice do not display elevated agonistic behaviors in intruder-resident or neutral arena tests of aggression. The goal of the proposed studies is to examine the sex difference in aggressive behavior of nNOS-/- mice, and to determine the contribution of serotonin in aggressive behavior of nNOS-/- mice. There are four specific aims of the proposed studies: (1) to use a pharmacological manipulation, 7-nitroindazole (a specific nNOS antagonist), to confirm the observation that nNOS is important in mediating aggression, (2) to determine the contribution of sex steroid hormones to the sex difference in aggressive behavior among nNOS-/- mice, (3) to establish if female nNOS-/- mice display increased maternal aggression relative to WT mice, and (4) to determine the role of serotonin in the mediation of aggression in nNOS-/- animals.

DESCRIPTION (provided by applicant): Infection results in the rapid onset of adaptive sickness responses, termed the acute phase response, and includes physiological changes such as fever, increased sleep, as well as behavioral changes such as reduced food and water intake, activity, exploration, and social interactions. These so-called "sickness behaviors" are organized, adaptive strategies that are often crucial for host survival, rather than nonspecific manifestations of illness. Mounting an immune response is energetically costly. For many animals living in non-tropical habitats, a predictable annual energy shortage occurs each winter. During the short days of winter, low food availability often coincides with high thermoregulatory demands in low temperatures. Specific adaptations to conserve energy, such as inhibiting reproduction and growth, have evolved among animals to enhance winter survival. Immune function and responses to infection are also constrained by available energy, and may be altered by changes in the external environment. The proposed experiments are designed to investigate whether sickness behaviors or immune cell trafficking may be influenced by available energy or other factors signaled by melatonin. The specific aims of the proposed research are: (1) To determine if early immune activation evokes long-term reproductive costs. (2) To determine if short-day alterations in sickness responses are mediated by melatonin. (3) To discover if melatonin acts directly on lymphocytes to alter cytokine production. (4) To determine if short days and melatonin reduce the duration of fever by affecting brain levels of cyclooxygenase (COX) and interleukin(IL)-1a. (5) To determine if photoperiod and melatonin affect immune cell populations and leukocyte trafficking. (6) To determine if photoperiod influences the extent to which stress compromises immune function. Taken together, these studies may reveal novel therapeutic uses of melatonin on fever and anorexia.

ABSTRACT NOT PROVIDED

DESCRIPTION (provided by applicant): A major goal of neuroscience is to understand the mechanisms mediating brain plasticity. Among humans, seasonal alterations in mood, immune function, and response to brain damage are well-documented. We recently established an experimental model of photoperiod-induced plasticity in brain structure and function. Male Peromyscus mice reduce hippocampal size and spatial memory performance in short days; short days decrease apical CA1 spine density and increase basilar CA3 spine density suggesting that photoperiod, encoded by melatonin, alters brain structure and cognitive function. We will use this system to understand the factors driving such changes. Aim 1: What aspects of brain morphology and cognitive function respond to photoperiod or melatonin? We will study changes in: (1) hippocampal volume/dendritic morphology, (2) hippocampal neurogenesis, (3) long-term potentiation (LTP), and (4) learning and memory. Aim 2: What is the role of gonadal steroid hormones in mediating photoperiod-induced brain plasticity? We will examine aromatase activity, androgen (AR), and estrogen receptor (ER) subtype (ER1 and ER2) expression in long- vs. short-day mice, and determine whether gonadectomy or treatment with AR and/or ER receptor antagonists eliminates photoperiodic differences in brain plasticity. Aim 3: How does photoperiod and androgen affect brain-derived neurotrophic factor (BDNF), and brain plasticity? Using qRT-PCR, photoperiod and androgen effects on BDNF will be assessed. Aim 4: What is the time course by which photoperiod affects brain and behavioral plasticity? We will examine mice at different time points during the switch between photoperiods. Also, because season of birth influences many human neurological disorders, we will examine the enduring effects of photoperiod on brain and behavior of mice born in long or short days, then reared in the same or opposite photoperiod. Our combinatorial approach will provide insight into the treatment of seasonal cognitive and affective disorders, developmental disabilities, and help establish general mechanisms underlying brain plasticity. PUBLIC HEALTH RELEVANCE The role of photoperiod on brain and behavioral plasticity is understudied. Traditionally, neuroscientists interested in seasonal brain plasticity have focused on songbirds. This proposal adds a novel dimension to the study of seasonality, as well as the study of brain and behavioral plasticity. The working hypothesis underlying all of our proposed studies is that short days are associated with individuals switching resources to gain energetic savings. In other words, we visualize short-day changes in brain and hippocampal size, dendritic spines, neurogenesis, and spatial learning and memory performance as adaptations due to changing energetic conditions that are dependent on photoperiod, biological clocks, and melatonin. Of particular importance is the postulate that seasonal variation in certain human disorders may be due at least in part to variation in photoperiodic effects of brain structure and function. The evolutionary history of humans suggests that almost all ancestral stocks of Homo sapiens have lived at one time or another in situations where seasonal adjustments in physiology might have proven advantageous. Although the available data suggest that modern human reproduction is not susceptible to photoperiodic regulation, brain plasticity and behavioral function very well might be. This possibility deserves serious consideration. Importantly, seasonal changes in neuroendocrine function, hypothalamic expression of vasopressin, vasoactive intestinal polypeptide (VIP), and serotonin function have also been reported in humans. Seasonal changes in human behavioral pathology are also observed in anxiety and depression, migraine headaches, as well as incidence, severity, and mortality of strokes. Thus, despite the relative lack of seasonal organization of reproductive function, it is apparent that humans retain responsiveness to photoperiod, and that photoperiod-mediated adjustments in rodent brain and behavior may be important to understand seasonal changes in human brain and behavior.

Throughout their history, both humans and nonhuman animals experienced dark nights. This started to change ~120 years ago with the development of electrical lighting which illuminates our nights and most recently has led to urban and suburban light pollution. Normal physiology and behavior display a circadian organization that depends on clear light and dark signals, but the presence of light at night potentially disrupts temporal organization. Because of the convenience of electric lights, little thought has been given to their biological effects. This project will examine the effects of dim light at night on immune function in hamsters. By using established physiological, molecular, and genetic tests of immune function, the effects of night-time light on the immune system will be established. The project will train high school, undergraduate, graduate and postdoctoral trainees of both sexes from diverse cultural and historically-underrepresented backgrounds during the conduct of this project. All experimental results will be made easily accessible to the general public through publications, websites, popular press, and presentations at professional societies, community forums, colleges, and universities. An interactive website where scientists and lay people can upload light-at-night illumination levels to get a finer-grain appreciation of light pollution than typically provided by satellite maps will be established and maintained. The results will provide insight into how vertebrates may respond to global change in the near future, how emergent diseases may arise as immune regulation changes, as well as provide unique insights as to how environmental control mechanisms evolved and how they are potentially disrupted by unintended light pollution.

Deep within the brain resides a set of neurons that have inherent time-keeping capacity. The electrical firing properties of this cell population (referred to as the suprachiasmatic nucleus, or SCN) generates a 24 hour oscillation (referred to as a circadian rhythm) that functions as a timing cue to ancillary neuronal oscillator populations found throughout the rest of the brain. This circadian timing circuit has remarkable power over the nervous system. For example, key functions of the nervous system, such as the sleep/wake cycle, and complex cognitive processes (e.g., learning, memory and critical thinking skills) are modulated by this circadian rhythm. Further, the disruption of this circadian timekeeping system has profound effects on mood, cognitive capacity and sleep. Notably, the disruption of circadian timing can result from alterations in one's work schedule (often seen in night shift workers), or from a number of acquired and congenital disorders of the brain (e.g., depression, Alzheimer's disease and Huntington's disease). In fact, the disruption of circadian timing in individuals with Alzheimer's disease is considered to be one of the most pressing issues for health care workers. This rich series of observations raises questions about the functional relationship between the SCN and ancillary neuronal oscillator populations, and, relatedly, about the underlying neuronal circuits that modulate cognitive capacity over the circadian cycle. In this application, the researchers propose to employ a wide array of innovative interdisciplinary approaches to determine the functional significance and mechanistic underpinnings by which circadian clock timing in brain circuits modulate complex cognitive processes, such as learning and memory. The research will also provide an opportunity for direct student involvement in research and the data from the study will be used to generate an interactive website for outreach to the public and included in the Brain Awareness Program that presents research findings to elementary and middle schools.

Within the central nervous system, rhythmicity is not restricted to the SCN, but rather, is found in a diversity of brain regions. In line with this, forebrain structures, including the cortex and hippocampus, express all of the molecular components required to drive clock timing. Here, the researchers propose to systematically test the contribution of forebrain clocks to the circadian regulation of learning and memory. This application is predicated on the hypothesis that the SCN clock works in a coordinated manner with ancillary hippocampal/forebrain oscillators to regulate cognitive capacity as a function of the time of day. To test this idea, the researchers propose to use an innovative set of transgenic animal models that will allow them to resolve clock timing at a single cell level, and thus, create a systems and cellular level blueprint of hippocampal timing (Objectives 1 and 2). This aim will allow the researchers to identify the cycling cell types (e.g., glutamatergic excitatory neurons, GABAergic inhibitory neurons, astrocytes and microglia) and to assess the phase relationship of discrete oscillator populations. Addressing these questions is key to the understanding of the tightly intertwined relationship between circadian timing and cognition. In Objectives 3 and 4, the researchers will use conditional knockout technology to disrupt forebrain circadian timing and assess the effects on learning and memory. Importantly, with this approach, SCN timing will be intact, and thus, the scientists will be able to specifically test the contribution of forebrain oscillators to learning and memory. These data sets will provide new insights into the complex processes by which the clock shapes cognition, and in turn provide a foundation for further experimental approaches designed to reveal clock functionality in a broad range of physiological and psychological processes.

SUMMARY OF PROPOSED ADMINISTRATIVE SUPPLEMENT. We are requesting a one-year Alzheimer's-focused administrative supplement for grant RO1-NS 92388 (Notice Number: NOT- AG-18-039). In the course of our work on cardiac arrest outcomes, we have discovered that several features of the brain vasculature are altered by exposure to dim light at night, and that the changes occur rapidly. For example, in otherwise healthy, young adult mice as little as four nights of exposure to dim light at night (5 lux) causes a reduction in hippocampal blood vessels. Likewise, markers of angiogenesis (e.g., VEGF) are also reduced. Based on these observations, we hypothesize that exposure to light at night may promote vascular cognitive impairment and dementia (VCID). Indeed, most victims of VCID live in spaces that are illuminated by dim light at night to ensure the safety of the residents and nightshift staff. We believe that circadian disruption caused by light at night promotes the deterioration of the brain vasculature, resulting in cognitive impairments. To test this hypothesis, we plan to expose aged (72 week old) male and female mice to dark nights or dim light at night, then after 1 versus 8 weeks of the lighting condition we will commence cognitive testing. At these time points, brain vasculature, markers of angiogenesis, and neuroinflammation will be assessed in a separate cohort of mice. In addition, we will include experimental groups in which mice are exposed to a restricted spectrum of dim blue or dim red light at night (equalized for lux and photic energy). We predict that mice exposed to dim blue and or white light at night will display increased neuroinflammation, and cognitive and blood flow impairments relative to mice exposed to dim red light at night or dark nights. This outcome would suggest that restricting the wavelength of nighttime lighting could offer a low-cost, effective means to delay or prevent VCID in elderly individuals. This administrative supplement would allow us to develop a foundation on which to build a full R01 on VCID to understand the mechanisms involved.

? DESCRIPTION (provided by applicant): Sleep disruption is one of the most common and potentially detrimental long-term side effects of chemotherapy in breast cancer patients. The majority of patients undergoing chemotherapy report acute sleep disturbances, and as many as 60% of survivors go on to develop chronic sleep disruption, which can persist for more than a decade following treatment. Despite this high incidence, the etiology of sleep disruption among breast cancer patients remains unknown. The goal of the proposed studies is to elucidate the physiological mechanisms through which chemotherapy contributes to the development of sleep disruption. Aim 1 will use mice to establish whether a causal relationship exists between chemotherapy-induced inflammation and sleep disruption. Specifically, we will determine whether regions of the brain associated with sleep have increased expression of proinflammatory cytokines after exposure to chemotherapy, and whether suppressing inflammation via minocycline, an anti-inflammatory drug already available for use in cancer patients, preserves sleep during and after treatment with chemotherapy. In Aim 2, we will characterize sleep quantity and quality in breast cancer patients prior to chemotherapy and during the survivorship period using self-report measures and objective actigraph, EEG and EMG measures collected during stays in the Ohio State University Sleep Disorders Clinic; these measures will be correlated with serum biomarkers of inflammation. This study will provide the most comprehensive analysis of sleep in breast cancer patients to date, and together with Aim 1 will determine whether an interventional sleep study using minocycline is warranted in breast cancer patients. The long-range goal of the proposed research is to improve the mental and physical health of cancer patients, as well as their quality of life, through the normalization of sleep during chemotherapy treatment and throughout the survivorship period.

Abstract The widespread adoption of electric lighting in industrialized countries has led to significant exposure to artificial light at night (LAN). Exposure to LAN is strongly correlated with world-wide increases in the prevalence of obesity and metabolic disorders, as well as certain types of cancers. Circadian rhythms, which rely on distinct light-dark cycles for entrainment, can be disrupted by light at night. Elevated prevalence of cancer is associated with exposure to LAN that suppresses melatonin and disrupts circadian genes expression. Circadian output plays an important role in physiological processes by controlling many genes, among which are the cell cycle genes c-MYC, WEE1, Cyclin D and p21, the tumor suppressor gene p53, as well as the apoptotic caspaces. Mutation or epigenetic silencing of the clock genes plays an important role in carcinogenesis and this may explain how disruption of circadian rhythms by shift work predisposes to breast, colon, prostate, ovarian, lung, and hepatocellular carcinomas. People working night shifts display epigenetic alteration of the Cry2 and CLOCK genes. In contrast, the incidence of cancer, including pancreatic cancer, among Old World Amish adult men and women, who are not exposed to LAN, is much lower than the general population. In addition, completely blind people have lower incidence of cancers compared to severe visually impaired people or the sighted population despite having much higher obesity rates than the Amish. Pancreatic cancer is among the most aggressive cancers with poor prognosis, short post diagnosis survival, and substantial economic burden. Night shift work can be one of the risk factors for pancreatic cancer. Circadian gene expression is dysregulated by pancreatic ductal adenocarcinoma (PDAC). K-Ras mutations account for ~90-95% of PDAC. Tumor progression in K-Ras mutation requires a cellular context, in which activation of other genes such as Notch promotes the oncogenic effect of K-Ras; Notch is controlled by the clock genes, and disruption of which in the developing pancreas alters the balance and maturity of endocrine and exocrine cells. Overexpression of the Per2 gene decreased cellular proliferation and enhanced apoptosis in pancreatic cancer cells in synergy with cisplatin treatment and bilateral ablation of the SCN in mice also resulted in accelerated growth of pancreatic tumors. The working hypothesis of this project is that light at night disrupts circadian rhythms in cell cycling genes and this disruption hastens the onset and progression of pancreatic cancer. We will test this hypothesis in two specific aims. Specific Aim 1 will examine the effects of dLAN on blood metabolic profiles, as well as clock genes, IGF-1, and cell cycle genes in the pancreases of C57BL/6J mice. The hypothesis tested in this aim is that disruption of circadian rhythms by dLAN increases body mass associated with insulin resistance and elevates IGF-1, c-myc, and cyclin D1 gene expression associated with reduced expression of the core clock genes. Specific Aim 2 will examine the effects of dLAN on progression of tumor growth and the expression levels of clock, IGF-1, and cell cycle genes in K-Ras transgenic mice. The hypothesis tested in Aim 2 is that disruption of circadian rhythms by dLAN suppresses core clock gene expression leading to disinhibition of the proliferative signaling pathways. This phenomenon leads to increased risk of tumor development in normal C57BL/6J mice or enhanced tumor growth in K-Ras transgenic mice.

CORE C (BEHAVIOR) ABSTRACT The Behavior Core provides assistance with behavioral phenotyping of mice and rats, including expert training and consultation on behavioral studies. Services include a comprehensive battery of behavioral tests for rodent models such as assessments of sensorimotor skills, balance and coordination, circadian organization, anxiety-like responses, depressive-like responses, and learning and memory.

Abstract Widespread adoption of electric lighting has led to significant exposure to artificial light at night (LAN). Although initially assumed innocuous, exposure to LAN disrupts circadian rhythms and is correlated with increased prevalence of several clinical disorders. This so-called light pollution began prior to a deep appreciation of the importance of circadian rhythms to typical, adaptive functioning. Our preliminary data indicate that exposure to LAN disrupts circadian rhythms, dramatically increases peripheral and central inflammation, and elevates pain responsiveness in mice. Pain is a significant cause of high medical costs, lost productivity, and a common pathway to opiate addiction. Currently, there are few optimal treatments for chronic pain and the underlying causes, and predictive factors that lead individuals from therapeutic use to opiate abuse remain unspecified. Pain responsiveness shows daily variation with elevated responses at night. We hypothesize that disrupted circadian rhythms, caused by exposure to LAN, drive inflammatory processes and influence pain responsiveness. We will test this hypothesis and predict that mice exposed to dim light at night (dLAN) will display elevated pain responsiveness. We further hypothesize that circadian responses to opiate management of pain are deranged by light at night. Thus, we predict that higher doses of opiates are required to obtain similar suppression of pain responses in animals exposed to dim light at night. These hypotheses will be tested in two specific aims. In the first specific aim, we will characterize the effects of dLAN exposure on pain responsiveness in mice. Because of the well-known sex differences in pain responsiveness, we will test both male and female mice in pain responsiveness after exposure to dLAN. Circadian clocks are entrained by light interacting with melanopsin-expressing retinal ganglion cells which are primarily responsive to short-wavelength (blue) light, and relatively unresponsive to long wavelength (red) light. Thus, we will examine pain responsiveness after exposure to dark, dim white, dim blue, or dim red light at night to test the hypothesis that exposure to dLAN comprised of wavelengths that affect circadian clock entrainment (white and blue) will elevate pain responsiveness, whereas exposure to dark nights or dim red light at night prevents elevated pain responsiveness. Specific Aim 2 will test the hypothesis that disruption of circadian organization by exposure to dLAN changes sensitivity/ responsiveness to opiates. We predict that dose responses to opiates will shift so that increased opiate dosages will be required to suppress pain responses. Taken together, the results of this project will fill an important gap in knowledge about the role of circadian rhythms in pain responses and pain treatment. If our hypotheses are not disproved, then these results could easily and inexpensively be translated to individuals suffering from pain?e.g., blue-light blocking goggles or other environmental lighting adjustments?to align circadian rhythms, to improve pain treatment outcomes, and avoid opiate abuse.