John H. Morrison - US grants

neoplasm /cancer pharmacology; automated data processing; chemical information system;

Alzheimer's disease (AD) involves a progressive global deterioration of intellectual function, manifested by disturbances in cognition, memory, language, visuospatial skills, judgement and personality. Such mental abilities require integration of information across many specialized regions of the cerebral cortex. Preliminary evidence suggests that AD may involve the severe loss of the structural and functional integrity of the corticocortical projection systems. This hypothesis is supported by the close correlation between the regional and laminar distribution of neurofibrillary tangles and the patterns of origin and termination of the major corticocortical systems. Neurofilament protein has been implicated in the formation of neurofibrillary tangles (NFT) in Alzheimer's disease. A monoclonal antibody to non-phosphorylated neurofilament protein (N-PNFP, SMI 32 of Sternberger-Meyer) labels a distinct subset of pyramidal cells in the normal human cortex. The distribution of labeled cells in normal brain is very similar to that of neurofibrillary tangles in brains from patients with Alzheimer's disease. In addition, in brains of AD patients, those regions and layers that normally contain a high density of SMI 32- immunoreactive (ir) cells now show large numbers of NFT and few SMI 32-ir cells. These SMI 32-ir cells have laminar locations identical with those neurons that are most likely to furnish the corticocortical and hippocampal association paths essential for the integrated, cohesive function of human cortex. The experiments outlined in this proposal are directed at determining the following: 1) distribution of SMI 32-labeled cells in normal human and monkey cortex, and the degree to which the cellular, laminar and regional patterns are similar in the two species, 2) the degree to which the labeled cells in monkey furnish long corticocortical projections 3) the regional, laminar, and cellular pathology of the SMI 32-labeled cells in AD and their relationship to other indices of AD pathology, particularly NFT and 4) the neurotransmitters utilized by neurons furnishing long corticortical projections in monkey, particularly in reference to somatostatin. These data will shed light on the neurological consequences of the proposed role of neurofilament protein in AD pathology, and may reveal the degree to which the degeneration of corticocortical projection systems is a key element of dementia.

The major neurodegenerative disorders display a high degree of selective vulnerability in regard to the distribution of pathologic lesions. This selective vulnerability is apparent in the disease-related profile of neuronal loss, and degeneration of specific pathways. For example, in Alzheimer's disease (AD), the distribution of pathologic profiles and cell loss suggest that the cells of origin and circuits that comprise certain parahippocampal projections and corticocortical circuits in neocortex are devastated in AD, whereas many other elements of cortical circuitry are resistant to pathology. Patterns of selective vulnerability in the neocortex offer important clues as to which cortical circuits are compromised in a given disease, but our ability to relate such patterns to potential cellular or molecular pathogenetic mechanisms is greatly hampered by our lack of data correlating biochemical phenotype with connectivity in the primate neocortex. This proposal is designed to provide such information on the corticocortical projections in the monkey. We have demonstrated that the pyramidal cells that furnish corticocortical projections are not homogeneous in regard to biochemical phenotype and/or morphology and thus, by our criteria do not represent a uniform cell type. We hypothesize that both the cytoskeletal and neurotransmitter profiles of these neurons will be a crucial characteristic of their biochemical phenotype and will relate systematically to their connectivity patterns. For example, specific corticocortically projecting neurons win be characterized as to their content of neurofilament and microtubule-associated proteins, as well as whether or not they use glutamate as a neurotransmitter, or contain receptors for glutamate, acetylcholine, or GABA and if so, the precise dendritic distribution of each receptor will be determined. In addition, die precise distribution of chemically identified afferents to corticocorically projecting neurons will be determined. Techniques that combine retrograde transport, immunohistochemistry and intracellular loading will be used to characterize several different classes of corticocortically projecting neurons. By considering location, connectivity (synaptic inputs and efferent target), morphology, and biochemical phenotype, subtypes of corticocortically projecting cells can be defined and their relative contribution to a given corticocortical projection can be determined. We predict that the comprehensive profile Of a given cell, and in turn, a given projection, will be strongly related to its role in normal cortical function and to its vulnerability in AD or other neurodegenerative disorders. If we can pinpoint the elements of the biochemical and anatomic phenotype that are most clearly linked to differential cellular vulnerability in AD, then we will be one step closer to developing means of protecting those neurons that degenerate in AD. The protection of these neurons must be the paramount goal in developing a strategy for the management of AD, since prevention of a neurodegenerative disease is much more likely to be achievable than the development of a cure.

The central dopamine (DA) system has been implicated in the pathophysiology of both Parkinson's disease (PD) and schizophrenia, as well as in the neuropharmacology of drug abuse. In the case of PD, cellular pathology of the nigro-striatal pathway has been defined, although the extent to which the cortical DA systems are disrupted in PD remains controversial. The situation with schizophrenia is similar in that although DA antagonists are useful in alleviating symptoms, the degree to which structural pathology exists in the DA innervation of cortex is not clear. Our ability to develop testable hypotheses on the relative contributions of disruption of striatal and/or cortical DA systems in neurologic diseases and drug abuse has been greatly hampered by the lack of precise data on the anatomic organization of cortical DA systems in primate. This limitation also makes it difficult to determine the potential role of the cortical dopamine system in normal functions, such as cognition. More specifically, investigators in the area have yet to make the transition from an understanding of cortical DA innervation that is based on preferred layers and regions to a cellular/synaptic model that is integrated into modern concepts of cortical organization. Recent advances in molecular neurobiology and neuroanatomy have occurred that make such a transition feasible. We have hypothesized that the pyramidal cells that furnish key corticocortical projections are a primary DA target neuron in association and limbic cortices. The experiments outlined in this proposal will test this hypothesis and in the process develop a synthetic model of DA innervation that integrates the distribution of pre-synaptic DA markers (i.e., terminals) with post-synaptic DA markers (i.e., receptors). This integration will occur on regional, laminar, cellular, and sub-cellular levels. Riboprobes and antisera will be prepared against specific DA receptor subtypes, and the density and distribution of these receptors will be quantified in respect to specific cortical regions and layers. The density of DA terminal varicosities will also be quantified, and analyzed ultrastructurally. In addition, methods combining retrograde transport, cell loading, and immunocytochemistry will be used to map out the distribution of all three receptor subtypes and incoming DA terminals along the dendritic tree of corticocortically projecting neurons with a known efferent target. These data will allow for the putative role of DA in neurologic disease, drug abuse, and normal brain function to be analyzed and conceptualized within the framework of precisely defined cortical circuits that are amenable to further anatomic, physiologic and behavioral dissection.

The central dopamine (DA) system has been implicated in the pathophysiology of both Parkinson's disease (PD) and schizophrenia, as well as in the neuropharmacology of drug abuse. In the case of PD, cellular pathology of the nigro-striatal pathway has been defined, although the extent to which the cortical DA systems are disrupted in PD remains controversial. The situation with schizophrenia is similar in that although DA antagonists are useful in alleviating symptoms, the degree to which structural pathology exists in the DA innervation of cortex is not clear. Our ability to develop testable hypotheses on the relative contributions of disruption of striatal and/or cortical DA systems in neurologic diseases and drug abuse has been greatly hampered by the lack of precise data on the anatomic organization of cortical DA systems in primate. This limitation also makes it difficult to determine the potential role of the cortical dopamine system in normal functions, such as cognition. More specifically, investigators in the area have yet to make the transition from an understanding of cortical DA innervation that is based on preferred layers and regions to a cellular/synaptic model that is integrated into modern concepts of cortical organization. Recent advances in molecular neurobiology and neuroanatomy have occurred that make such a transition feasible. We have hypothesized that the pyramidal cells that furnish key corticocortical projections are a primary DA target neuron in association and limbic cortices. The experiments outlined in this proposal will test this hypothesis and in the process develop a synthetic model of DA innervation that integrates the distribution of pre-synaptic DA markers (i.e., terminals) with post-synaptic DA markers (i.e., receptors). This integration will occur on regional, laminar, cellular, and sub-cellular levels. Riboprobes and antisera will be prepared against specific DA receptor subtypes, and the density and distribution of these receptors will be quantified in respect to specific cortical regions and layers. The density of DA terminal varicosities will also be quantified, and analyzed ultrastructurally. In addition, methods combining retrograde transport, cell loading, and immunocytochemistry will be used to map out the distribution of all three receptor subtypes and incoming DA terminals along the dendritic tree of corticocortically projecting neurons with a known efferent target. These data will allow for the putative role of DA in neurologic disease, drug abuse, and normal brain function to be analyzed and conceptualized within the framework of precisely defined cortical circuits that are amenable to further anatomic, physiologic and behavioral dissection.

The major neurodegenerative disorders display a high degree of selective vulnerability in regard to the distribution of pathologic lesions. This selective vulnerability is apparent in the disease-related profile of neuronal loss, and degeneration of specific pathways. For example, in Alzheimer's disease (AD), the distribution of pathologic profiles and cell loss suggest that the cells of origin and circuits that comprise certain parahippocampal projections and corticocortical circuits in neocortex are devastated in AD, whereas many other elements of cortical circuitry are resistant to pathology. Patterns of selective vulnerability in the neocortex offer important clues as to which cortical circuits are compromised in a given disease, but our ability to relate such patterns to potential cellular or molecular pathogenetic mechanisms is greatly hampered by our lack of data correlating biochemical phenotype with connectivity in the primate neocortex. This proposal is designed to provide such information on the corticocortical projections in the monkey. We have demonstrated that the pyramidal cells that furnish corticocortical projections are not homogeneous in regard to biochemical phenotype and/or morphology and thus, by our criteria do not represent a uniform cell type. We hypothesize that both the cytoskeletal and neurotransmitter profiles of these neurons will be a crucial characteristic of their biochemical phenotype and will relate systematically to their connectivity patterns. For example, specific corticocortically projecting neurons win be characterized as to their content of neurofilament and microtubule-associated proteins, as well as whether or not they use glutamate as a neurotransmitter, or contain receptors for glutamate, acetylcholine, or GABA and if so, the precise dendritic distribution of each receptor will be determined. In addition, die precise distribution of chemically identified afferents to corticocorically projecting neurons will be determined. Techniques that combine retrograde transport, immunohistochemistry and intracellular loading will be used to characterize several different classes of corticocortically projecting neurons. By considering location, connectivity (synaptic inputs and efferent target), morphology, and biochemical phenotype, subtypes of corticocortically projecting cells can be defined and their relative contribution to a given corticocortical projection can be determined. We predict that the comprehensive profile Of a given cell, and in turn, a given projection, will be strongly related to its role in normal cortical function and to its vulnerability in AD or other neurodegenerative disorders. If we can pinpoint the elements of the biochemical and anatomic phenotype that are most clearly linked to differential cellular vulnerability in AD, then we will be one step closer to developing means of protecting those neurons that degenerate in AD. The protection of these neurons must be the paramount goal in developing a strategy for the management of AD, since prevention of a neurodegenerative disease is much more likely to be achievable than the development of a cure.

One of the major mechanisms of cell death that has been implicated in several neurodegenerative disorders, including Alzheimer's disease, is glutamate-receptor mediated excitotoxicity. Until recently it was not feasible to delineate with precision the glutamate receptor subunit profile of identified neurons and circuits in the cerebral cortex. However, with the molecular characterization of the specific subunit proteins and the development of riboprobes and subunit specific antibodies, it is now feasible to develop detailed glutamate receptor profiles of both vulnerable and resistant neurons that are subunit-and family-specific that will delineate the degree to which certain glutamate receptor subunit molecules might be implicated in the differential vulnerability that is apparent in Alzheimer's disease. Within this context this project will be directed at the four major goals. 1) Screening of monoclonal antibodies that are directed against subunits of the non-NMDA(GluR1-7) and NMDA families of glutamate receptors for their effectiveness in immunohistochemical studies of human cortex. 2) These immunohistochemical probes, as well as riboprobes, will be used to analyze the regional, laminar and cellular distribution of specific glutamate receptor subunit proteins and related mRNAs in monkey and human neocortex and hippocampus. 3) Double labelling paradigms will be employed to determine the comprehensive glutamate receptor profile a well as correlations between the presence of certain glutamate receptor subunits and other neurochemical characteristics that have been correlated with either vulnerability or resistance to degeneration in Alzheimer's disease. These studies initially will concentrate on colocalization with cytoskeletal and Ca+2-binding proteins. 4) Alzheimer's disease related changes in the dendritic, cellular, laminar, or regional distribution of such subunit proteins and/or related mRNA's will be determined through comparison of immunohistochemical patterns in brains from Alzheimer's disease patients, elderly controls, and young controls. Through this combined analysis of normative human material, Alzheimer's disease tissue, and genetically manipulated mice it is hoped that we will be able to develop a precise glutamate receptor profile that can be linked to the differential vulnerability apparent in Alzheimer's disease and within this context develop quantitative data on shifts in the expression of specific subunits and related glutamate receptor families that might be causally related to the neurodegeneration of specific subsets of cortical neurons that occurs in Alzheimer's disease.

The primary goal of this Program Project is to reveal the important interactions between the brain and female reproductive senescence, with particular attention to the impact of these evens on memory, cognition, and attention. While animal studies have demonstrated clearly that changes in circulating estrogen levels affect cellular and molecular attributes of certain neural circuits, the link between such observations and the human data on peri- and post-menopausal memory impairment, beneficial neurobehavioral effects of estrogen replacement therapy (ERT), and potential decreased risk of Alzheimer's disease with ERT are far from clear. It is our strong conviction that the Program Project mechanism, as implemented in this proposal, is required to analyze the spectrum of mechanistic analyses from the in vitro level to an in depth structural and functional assessment of the effects of ERT on behaviorally characterized non-human primates. Though tight interactions between projects 1, 2, and 3, studies in rodents will extend from a) mechanistic analyses of estrogen's role in synaptogenesis and neurodegeneration to b) estrogen- and age-induced alterations in the circuits that directly control reproductive function and c) estrogen and age-induced plasticity in the circuits that mediate memory. The rodent analyses, particularly the in vitro studies of Project 1, will be a crucial testing ground for revealing novel molecular and cellular links to estrogen-brain interactions that could be pursued in the primate model. Core A as well as Projects 2, 3, 4, and 5 will converge on the non-human primate model. They will evaluate the structural (hippocampal, glutamate, cholinergic, basal forebrain, and dopaminergic mesocortical systems) and functional (behavioral assays of memory, cognition, and attention) consequences of ERT in young and aged Rhesus monkeys, as well as provide a detailed assessment of endocrine status and hypothalamic regulation of reproductive function. Rhesus monkeys of different ages that have been surgically ovariectomized with and without ERT as well as those that have transitioned through age-related menopause will be employed in this Program Project. These animals will be the object of detailed endocrine, neurobiological, and behavioral analyses in an integrated effort to reveal the effects of interactions of estrogen and aging in the brain. These studies will lay the groundwork for more informed approaches to ERT in humans in order to help ameliorate neurodegenerative processes, as well as to promote successful brain aging.

neuropathology; cognition disorders; neurofibrillary tangles; neurofilament proteins; Alzheimer's disease; aging; diagnosis design /evaluation; AMPA receptors; entorhinal cortex; phosphorylation; hippocampus; dentate gyrus; dementia; early diagnosis; neurofilament; tau proteins; NMDA receptors; confocal scanning microscopy; immunocytochemistry; human tissue;

In human, estrogen replacement therapy (ERT) improves memory performance in ovariectomized (OVX) and post-menopausal women and is thought to decrease the risk of Alzheimer's disease. Changes in circulating levels of estrogen in rat affect the synaptic properties of hippocampal circuits that mediate memory, and these effects appear to be NMDA receptor-dependent. In addition, a high degree of NMDA receptor plasticity occurs in response to aging and estrogen manipulations in hippocampus that is cell class- and circuit-specific. In collaboration with the other four Projects and Core A, this Project will employ both rat and non-human primate models to develop a comprehensive animal model of the impact of estrogen depletion and ERT on NMDA receptors and hippocampal circuits with respect to memory performance. The degree to which the impact of estrogen on these circuits is comparable in young and old female rats and monkeys will also be investigated. Several relevant neurobiological parameters will be analyzed and compared in ovariectomized (OVX) animals with and without ERT, as well as in aged monkeys that are pre- and post-menopausal. In Specific Aims 1-3, morphologic parameters such as neuron number, dendritic arbor, and spine density will be analyzed, as well as quantitative confocal microscopy, and post-embedding immunogold electron microscopy will be used to de3velop a quantitative database of these parameters in OVX versus OVX with ERT in old and young adult females of both species. In Specific Aim 4, the most robust and functionally relevant morphologic and neurochemical attributes that are responsive to estrogen in S.A.s 1-3 will be considered in relation to behavioral parameters in monkeys that have been tested for memory performance and attention in Project 5. In collaboration with Project 2, Specific Aim 3 will investigate the most robust morphologic and neurochemical effects of OVX and ERT in animals 25-28 years old that are either still cycling or post-menopausal, in order to drawl parallels between surgically induced and naturally occurring menopause. This comprehensive approach will delineate the interactions among estrogen levels, hippocampus, NMDA receptors, memory, and aging and lay the groundwork for more informed approaches to ERT in humans with respect to the neurologic and behavioral manifestations.

Recent cellular analyses of the aging brain have revealed that phenotypic shifts in markers of neurotransmission are likely to be prime contributors to functional decline such as age-related memory impairment. Such studies have successfully dissociated this important set of age-related processes from the neuron loss and degenerative events associated with Alzheimer's Disease (AD). From this perspective, the health of the excitatory circuit and the glutamatergic synapse has become a focal point for aging research. In addition, there is increasing evidence for extensive plasticity at the synapse involving specific receptor subunits and associated proteins that may profoundly impact function. We will apply these concepts of phenotype plasticity to the neurobiology of aging, and test the hypothesis that aging results in shifts in glutamate receptors (GluRs) in a subset of hippocampal and neocortical circuits that could result in age-related memory impairment. This will involve the application of high resolution, quantitative analyses of the morphologic and molecular attributes of the glutamatergic synapse under a variety of conditions across four Specific Aims. Specific Aim 1 involves the analysis of age-related shifts in the GluR profile (e.g., multiple NMDA and AMPA receptor subunits) in key hippocampal circuits in young and aged rat and monkey cohorts that have been behaviorally characterized. The combined neurobiological/behavioral database allows for the direct linkage of the cellular and synaptic observations to age-related behavioral impairments. Specific Aim 2 will test the hypothesis that corticocortical connections between temporal and prefrontal association regions will display structural and neurochemical age-related alterations that could underlie age-related cognitive impairment. These studies will be carried out in Macaque monkeys, where we will characterize phenotypic changes in the aging corticocortical circuit, particularly with respect to the synaptic NMDA and AMPA receptors mediating inputs to these corticocortical neurons. Specific Aim ,3 will use a rat lesion model to investigate GluR plasticity in the context of individual and combined loss of two hippocampal inputs that are highly vulnerable in AD and aging; the perforant path input from entorhinal cortex, and the cholinergic input from the medial septal/diagonal band complex. Specific Aim 4 will delineate the cellular and synaptic adjustments in NMDA and AMPA receptors that occur in a transgenic mouse that overexpresses a single subunit, NR2B, which results in enhanced learning and memory. These Specific Aims converge on critical issues of GluR plasticity, synaptic specificity, and aging to delineate the phenotypic alterations of hippocampal and neocortical circuits that lead to impaired memory.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The primary goal of this Program Project is to investigate interactions between the aging brain and female reproductive senescence. Animal studies have demonstrated clearly that changes in circulating estrogen levels affect cellular and molecular attributes of certain neural circuits and related cognitive functions. However, the link between such observations and the human data on peri- and post-menopausal memory impairment, beneficial neurobehavioral effects of estrogen replacement therapy (ERT) or combined hormone replacement therapy (HRT) and protection against Alzheimer's disease are far from clear. Recent studies from the Women's Health Initiative on potential negative effects of a commonly used combined hormone replacement (HR) regimen have brought these issues to the forefront, and reinforced the need for additional scientific data on which to base therapies that are more physiological and beneficial to women. The Program Project mechanism is ideally suited for a full spectrum analysis of the key issues;from signaling mechanisms of estrogen in the brain to an in-depth structural and functional assessment of the effects of estrogen on the circuits regulating reproductive function (hypothalamus), to the effects of estrogen and aging on cognition and related cortical circuits. Projects 1, 2, and 3 will converge on the rodent model for detailed mechanistic and ultrastructural analyses of estrogen-induced plasticity, interactions with progesterone, and alterations in estrogen-induced plasticity due to aging. Core A and Projects 2, 3, 4, and 5 will converge on the nonhuman primate model (NHP) to study similar systems in NHPs treated with one of several clinically relevant HR regimens involving different schedules of estrogen and progesterone replacement. The aged NHPs will have extensive neuropsychological assessment aimed at determining age, estrogen, and progesterone effects on medial temporal lobe and prefrontal functions. We will investigate the neurobiological effects of multiple HR regimens in young and aged NHPs to reveal key synaptic and cellular reflections of estrogen-induced plasticity as well as effects on neurogenesis, and potential modifications induced by progesterone. In the aged animals, we will illuminate the underlying neurobiological events responsible for cognitive enhancement.

Clinical and preclinical data suggest that estrogen depletion and replacement impact cognitive function, and experimental data suggest that this may involve synaptic changes in hippocampus and prefrontal cortex. However, aging also affects cognition and related circuits, thus, we need to understand how neural and endocrine senescence interact if we are to understand the neurobiology of menopause and design appropriate hormone replacement strategies. We will continue to investigate both rat and non-human primate models of estrogen depletion and replacement to elucidate the synaptic basis of estrogen-induced cognitive enhancement, and age-related differences in response to estrogen. Expansion over the last funding period will include additional molecular targets for electron microscopy, an increased focus on prefrontal cortex, and new hormone replacement protocols that have high clinical relevance. Specific Aim 1 will determine how long-term cyclical exposure to estrogen affects spine number, pyramidal cell morphology, and the molecular profile of excitatory synapses in hippocampus and prefrontal cortex of young and aged rhesus monkeys, with particular focus on NMDA receptors, estrogen receptors, and related signaling molecules. We will then determine which of these indices are most directly related to the cognitive enhancement that follows from this treatment. Specific Aim 2 will use the rat model to elucidate the molecular basis of the age-related loss of synaptic resiliency in response to estrogen, as well as the effects of progesterone on estrogen-induced plasticity. We hypothesize that a loss of synaptic resilience in the aged females makes them more dependent on estrogen for optimal performance. Aim 3 will employ multiple hormone replacement regimens in young ovariectomized monkeys to investigate the neurobiological effects of chronic vs., cyclical estrogen, as well as the impact of continuous or cyclical progesterone on estrogen-induced plasticity. We hypothesize that chronic and cyclical exposure to progesterone will differentially modulate the effects of estrogen. Specific Aim 4 will use a similar comprehensive set of hormone replacement regimens in aged behaviorally characterized monkeys to determine which regimens are most successful at restoring youthful synaptic, cellular, and behavioral profiles. Such data will inform the clinical community on which hormone replacement regimens are appropriate for the aging brain.

DESCRIPTION (provided by applicant): Experiments proposed in this application bring into convergence current progress from the broader field of learning and memory research with recent findings in aged monkeys, toward addressing a new generation of questions concerning the neurobiology of normal cognitive aging in primates. The overall aims of the research program are to define the effects of normal aging on the information processing capacities that enable episodic memory, and to test the proposal that age-related decline results from large-scale restructuring of the neural networks critical for memory, regulated in part by ovarian senescence. Fourteen young adult (~5-10 years) and 18 aged (~22-28 years) female rhesus monkeys will be tested across an extensive neuropsychological battery consisting of both conventional, well-established procedures, including repeated assessment on the classic delayed response test, and a number of recently validated tasks aimed at assessing key operating characteristics of memory. Including standard tests of learning and memory is important to provide continuity with our earlier behavioral studies, and importantly, to establish a baseline for gauging the relative sensitivity and selectivity of newer tests to age-related impairment. These latter tasks will evaluate candidate processing functions and representational capacities thought to enable episodic memory: 1) the contribution of recollection and familiarity to visual recognition, 2) the temporal organization of memory, 3) memory for the context in which events occur, and 4) the relational organization of memory. By defining the specific nature of age-related memory impairment, the aim is to establish an optimally sensitive framework for relating functional decline to underlying neurobiological and endocrine changes. Toward this end, behaviorally characterized monkeys will receive annual structural magnetic resonance imaging (MRI) and positron emission tomography (PET) scans with the goal of testing several targeted hypotheses about the integrity of neural systems critical for normal memory, in close temporal contiguity with behavioral assessment. The results will also be evaluated by exploratory SPM analysis, suited to revealing unanticipated regions of age-related metabolic change. Continuing a long-standing theme of the project, menses activity and ovarian hormone profiles will be documented regularly for all subjects over the course of the experiments. By this integrated, multidisciplinary approach, the overall aim is to establish a unified account of the critical relationships between cognitive, neurobioological and endocrine consequences of normal aging in primates.

The goal of the Administrative and Data Management Core (Core B) of this Program Project Grant (PPG) is to maximize the productivity of all participants by the coordination and integration of scientific, fiscal and administrative activities, and provide a coordinated mechanism for data analysis and management. Core B is directed by the overall PI of the PPG, will continue to provide support to all four Projects in the PPG, as well as Core A, The Nonhuman Primate Core, at the California National Primate Research Center (CNPRC). The specific responsibilities of Core B are as follows: 1) To provide leadership and an administrative framework to facilitate interactions and communications among all the participating Project and Core Leaders (PLs) and across the multiple sites by creating a centralized mechanism for the coordination and management of research activities. 2) To centralize the administration of fiscal, clerical and personnel matters, and provide an administrative liaison between the Grants and Contracts Office of the Mount Sinai School of Medicine and other sites where research is conducted. 3. To organize all travel for perfusions of non-human primates at the CNPRC and assure that tissues are properly distributed. To assist Dr. Gore as needed in organizing and coordinating all distribution of rat tissues, which originate from Project 2 at The University of Texas at Austin. 4) To provide assistance with statistical analysis to all individual Projects, and in particular, provide analysis for comparisons of findings across Projects. Also, Core B will provide a consolidated mechanism for data organization and storage. 5) To ensure the smooth function and integration of PPG components by organizing frequent informal meetings, video conferences, and teleconferences with other PLs as well as formal meetings with the External Advisory Committee. 6) To facilitate the use of resources generated through this program by other investigators. RELEVANCE (See instructions): This core fosters the integration and collaboration required for the Program Project participants to reach their goal: to understand the aging brain and female reproductive senescence and develop hormone treatments applicable to women that will maximize neurological health.

OVERVIEW ABSTRACT The California National Primate Research Center (CNPRC), located at the University of California, Davis, requests funds to renew the base operating grant #P51-OD011107 for the next five year period (May 1, 2018 through April 30, 2023). Currently in the 56th year of operation, the CNPRC serves a range of NIH-supported investigators and industry partners nationwide. From inception through the current year, the CNPRC has been highly responsive to the research community by providing high quality animals, facilities, tools, and services driven by the intellectual infrastructure of the Core Scientists in the service of our Mission: ?To improve human health and quality of life through support of exceptional nonhuman primate research programs?. The goals for the next funding period are reflected in the following Specific Aims: (1) Conduct state-of-the-art research and scientifically contribute to the understanding and treatment of human disease with nonhuman primate models across the age spectrum, (2) Provide exceptional nonhuman primate expertise and services to investigators at the local, regional, and national levels to advance NIH-supported research excellence, (3) Mentor and train the next generation of translational investigators with nonhuman primate expertise, and (4) Ensure the highest standards of responsible conduct of research and animal care. We will continue to emphasize team science aimed at major human health problems across the lifespan, with the goal of moving beyond traditional interdisciplinary efforts to true convergence on the research problems being addressed. Support is requested for Administrative Services (Director's Office, Administration and Operations Services, Information Technology Services, Facilities Improvement), Primate Services (Colony Management and Research Services, National Institute on Aging Colony, Primate Medicine Services, Anatomic and Clinical Pathology Services, Population and Behavioral Health Services, Genetics Management Services), Service Cores (Flow Cytometry, Inhalation Exposure, Multimodal Imaging, Primate Assay Laboratory), Scientific Research Units (Infectious Diseases, Neuroscience and Behavior, Reproductive Sciences and Regenerative Medicine, Respiratory Diseases), and for Outreach, the Pilot Research Program, and NPRC Consortium activities. Our over-arching goal is to achieve translational impact through preclinical programs housed at the CNPRC as well as through collaborative teams that reach out locally, nationally, and globally. We are committed to developing and providing a wide range of research opportunities that maximize use of the nonhuman primate model to improve human health. The institutional commitment from UC Davis to the CNPRC has been reinforced in a manner that will facilitate our role in moving nonhuman primate research into the next era of convergent biomedical research.

Project Summary/Abstract Alzheimer?s disease (AD) is an extremely prevalent and severely disabling disease. Despite several decades of research, AD pathogenesis continues to be poorly understood, and we currently lack reliable biomarkers to spatiotemporally track and predict disease progression. Our overall goal is to address these challenges and develop enhanced biomarkers for diagnosing AD-pathology early and objectively tracking treatments. To that end, this proposal will utilize our highly translational monkey model of the early ?synaptic phase? of AD to assess the merits of in vivo imaging measures (from PET for synaptic density (using 11C-UCB-J) and glucose metabolism (using 18F-FDG), with structural MRI) against postmortem, state-of-the-art microscopic and histologic analysis of brain tissue, in a longitudinal study design. Our hypothesis is that PET measures, as surrogates for quantifying synaptic loss and metabolic dysfunction, will serve as early, independent predictive biomarkers for elevated AD risk and cognitive dysfunction. Our first specific aim will establish the correlation of our in vivo imaging measures with postmortem tissue markers of AD-associated pathologies in our monkey model versus age- and sex-matched control animals. Our second specific aim will map the spatiotemporal patterns of PET synaptic loss versus cerebral glucose metabolism in our monkey model versus control animals over a 12-week period. Completion of both aims will provide novel data to improve our understanding of synaptic neuropathology in AD development. Therefore, this proposal is highly responsive to the PAR-18-760. Positive findings would corroborate recent human studies investigating the role of synaptic dysfunction as a major factor for increased AD risk. Validation of in vivo imaging strategies in a relevant model system will contribute towards (i) optimizing the therapeutic window for future early AD treatments so that their efficacy can be maximized; (ii) testing mechanistic hypotheses associated with the role/blockage of synapse loss; (iii) rapidly evaluating new treatment strategies and their dose-response relationships. In summary, this project has the potential to provide key translational elements that will inform human studies evaluating in vivo markers of synaptic dysfunction.

Project Summary The vast majority of Alzheimer's disease (AD) cases are late-onset and it ss now widely believed that development of late-onset AD is the consequence of accumulated brain damage over many years. This process begins with the generation of abnormal oligomeric proteins (amyloid beta oligomers, A?Os) from misprocessed amyloid precursor protein. A?Os are toxic to synapses, and over time A?O buildup and synaptic damage lead to deposition of amyloid plaques and hyperphosphorylated tau protein causing neurofibrillary tangles and neuronal loss, the hallmarks of AD neuropathology. Despite tremendous resource investment, the translation of this mechanistic understanding of AD pathogenesis into new therapies for AD remains elusive. We propose the development of a nonhuman primate model of early AD pathogenesis based on exogenous administration of A?Os to middle-aged rhesus monkeys. Our extensive preliminary data show that a month of twice-weekly A?O administration causes synapse loss targeted to highly plastic thin dendritic spines, and neuroinflammation, changes that mirror what is thought to occur in the earliest prodromal phase of human AD. This model therefore addresses a key limitation of existing animal models of AD: it is based on the pathogenetic process thought to lead to the vast majority of human late-onset AD cases. Based on the acute effects of A?O administration on synaptic and glial markers in rhesus monkeys, we hypothesize that deficits in cognition and affect mirroring symptoms of AD in humans will develop over time in rhesus monkeys chronically treated with A?Os and relate to synaptic disease observed in postmortem histology. To test our hypothesis, rhesus monkeys treated with A?Os or a scrambled peptide control will complete cognitive and affective tasks sensitive to cortical and subcortical function. Our design provides detailed assessment of the time course of behavioral changes, and we will determine synaptic, neuronal, and glial markers in the brains of these monkeys concurrently with the emergence of behavioral deficits. Behavior will be tested in repeated cycles so that changes over time with increasing cumulative dose of A?Os can be determined. These experiments will provide a multi-faceted behavioral characterization of how synaptic dysfunction caused by A?O treatment impacts cognitive and affective behaviors dependent on multiple cortical and subcortical structures, and will let us develop A?O administration in rhesus monkeys as a model for testing interventions that may derail the progression of pathological cascades before full-blown AD develops, providing a new setting for developing treatments for an urgent public health problem.

Project Summary As the leading cause of age-related disabilities, neurocognitive diseases such as Alzheimer?s disease (AD) and other dementias are poised to significantly impact global health care as the population of people aged 60 and older nearly doubles in the next three decades. One group at a significantly greater risk of age-related neurodegenerative diseases are HIV-infected (HIV+) patients. An estimated 50% of HIV+ patients on antiretroviral therapy (ART) develop mild to severe impairments in brain function with age. Designated as HIV- associated neurocognitive disorders (HAND), this syndrome is expected to increase dramatically in the next decade as more than 70% of Americans with HIV turn 50 and older, and ART becomes more widely available in the developing world. The imminent global impact of HAND underscores the urgent need to understand the mechanistic basis of neurodegeneration in HIV+ patients on ART and devise effective interventions. This proposal is focused on understanding the immune mechanisms underlying age-related neurodegeneration following HIV infection using a robust rhesus model which recapitulates salient aspects of HIV pathophysiology in humans. In Aim 1 of this research project, we will establish the role of monocytes in neurodegeneration; specifically, pro-inflammatory monocytes. In Aim 2, we will determine the role of Th1, and Th17 CD4 T cell subsets in neurodegeneration. Considering that HIV and HIV-associated neuroinflammation interfere with amyloid and tau metabolism, in Aim 3 we will investigate whether pathological AD markers are induced during HIV-associated neuroinflammation. The collective complementary expertise of the investigators and collaborators in tackling the scientific questions posed in the application will facilitate an in-depth understanding of the immune and synaptic mechanisms underlying neurodegeneration. These preclinical studies will establish the mechanistic and experimental foundations to identify predictive biomarkers of HAND and subsequently enable opportunities in a relevant and tractable model for testing novel, targeted interventions as adjunctive therapy to ART. Only by quantifying measures of SIV-induced HAND sequelae in macaques can parameters of intervention be evaluated for efficacy prior to human studies.

Alzheimer?s disease (AD) is a devastating condition that affects more than 5 million Americans, with a total annual cost of more than $300 billion predicted in 2020. Currently there are no effective treatments to counteract or slow the progression of AD, with promising findings in rodents failing to translate into successful therapies for patients. Monkey models may provide a more powerful translational model. The goal of this proposal is to characterize a monkey model of tau pathology in AD. This is responsive to RFA-AG-21-003 requesting proposals that target the ?development, characterization, and validation of suitable new or unconventional mammalian non-murine models of AD that may represent improved translational potential by better replicating pathological features of the disease?. With respect to nonhuman primate (NHP) models of AD, the RFA states explicitly that ?NHP have a very high translational value because of their close relationship to humans in terms of phylogeny, genetics, physiology, cognition, emotion, and social behavior?. In this proposal we describe initial findings in a tau-based monkey model of AD and propose a program to fully develop and validate the model by three PIs who have decades of experience on aging and neurodegeneration in NHP models. We have targeted the highly vulnerable entorhinal cortex (ERC) for unilateral infusions of an adeno-associated virus expressing a double tau mutation known to cause tau-related dementia in humans (AAV-P301L/S320F) and characterized neuropathology at 3 and 6 months after viral injection in NHPs. This causes extensive and progressive neuroinflammation and tau-based neuropathology, including end-stage neurofibrillary tangles, in ERC and in hippocampal and neocortical targets of ERC. Preliminary PET imaging in these monkeys displays robust phospho-tau accumulation in the hippocampus. The progressive time course relative to the time of vector injection is a great strength in terms of using this model for therapeutic development. These early studies demonstrate the potential for this model to replicate pathological features of AD in the monkey brain and to capture aspects of pathology that have not been well-modeled in rodents. We propose to do a full, rigorous characterization of this model, including long-term behavioral assessment, in vivo imaging, fluid biomarker assessment, and microscopic analyses. Full characterization of this model, will provide a platform to test therapeutic agents at different points in the disease process.