1992 — 2004 |
Sesack, Susan R |
K02Activity Code Description: Undocumented code - click on the grant title for more information. R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R29Activity Code Description: Undocumented code - click on the grant title for more information. |
Cellular Basis For Dopamine Actions in Prefrontal Cortex @ University of Pittsburgh At Pittsburgh
DESCRIPTION (Adapted from applicant's abstract): The prefrontal cortex (PFC) guides complex behaviors such as working memory and future planning, and disruption of the cortical dopamine (DA) innervation in animals causes behavior consistent with PFC damage. Furthermore, schizophrenic patients exhibit behavioral deficits resembling PFC dysfunction, as well as morphological abnormalities and reduced DA innervation in the postmortem PFC. These observations suggest that an intact mesocortical DA innervation is essential for proper functioning of the PFC. However, the cellular mechanisms underlying DA's crucial modulation are not known. To understand these mechanisms, the synaptic organization of the mesocortical DA pathway must be clearly delineated. In the PFC of rodents and primates, DA terminals synapse on the dendritic spines and/or shafts of glutamate pyramidal neurons and GABA local circuit neurons; in both cases they converge with excitatory, presumed glutamate afferents. However, there remain several critical questions regarding this synaptic organization that can be addressed using a combined immunocytochemical, tract-tracing, and electron microscopic approach in the rat PFC. The central hypothesis of these studies is that DA terminals do not associate uniformly with all cell types, afferents, and cellular compartments. Study Q 1.1 will identify the subclasses of GABA local circuit neurons, defined by their content of calcium-binding proteins, that are synaptically innervated by DA terminals. Study Q1.2 will identify the sources of excitatory glutamate afferents that target the local circuit neurons receiving DA input. Study Q2.1 will identify the populations of PFC pyramidal neurons, deemed by their principal axon projections, that are synaptically innervated by DA terminals. Study Q2.2 will identify the sources of excitatory glutamate afferents that converge synaptically with DA terminals on common pyramidal cell dendrites. Study Q3.1 will identify differences in the distribution of DA terminal synapses on the apical and basilar tuft dendrites of individual pyramidal neurons. The latter study will be performed on neurons recorded intracellularly in vitro, thus permitting correlation of anatomical data with physiological and pharmacological experiments funded independently. These comparative studies will provide valuable information regarding extrapolation to humans of anatomical, physiological, and neurochemical data collected in experimental animals. Elucidating the synaptic organization of the mesocortical DA system will improve knowledge of the cellular mechanisms of DA modulation in cognition and the pathophysiology and treatment of major psychiatric disorders.
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0.936 |
1997 — 2002 |
Sesack, Susan R |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Dopamine Receptors and Lesion Induced Alterations in Structure and Expression @ University of Pittsburgh At Pittsburgh
Understanding the functions of dopamine (DA) requires the localization of all its major sites of action and hence, the identification of cellular processes that express receptors for DA. This is particularly true when considering that DA can signal neurons via unconventional forms of neurotransmission that are not constrained by synapses. We propose to utilize immunocytochemistry, electron microscopy, and quantitative stereological image analysis to address issues of DA receptor localization in the striatum of rats and non-human primates. We propose the following: (1) To qualify the distinguishing ultrastructural characteristics (dimensions, morphological features, and synaptic associations) of cellular processes immunoreactive for DA D1 and D2 receptors in the rat, in order to thoroughly document normal ultrastructure and to provide baseline information for subsequent species and lesion comparison. We hypothesize that the localization of D2 receptors will suggest a greater degree of presynaptic and non-synaptic actions of DA via this receptor subtype. (2) To determine how the ultrastructural characteristics of cellular processes immunoreactive for DA receptors are distinct in the monkey compared to the rat. We hypothesize that comparable synaptic and non-synaptic actions of DA in the two species will be reflected in similar morphology and synaptic relationships of the cellular processes expressing DA receptors. (3) To utilize a dual labeling immunocytochemical strategy to examine the co-distribution of DA D1 and D2 receptors with glutamate NMDA and AMPA receptors. Based on previous physiological data, we hypothesize that the D1 receptor will preferentially co-localize with the NMDA receptor, while the D2 receptor will be non-selectively distributed with both NMDA and AMPA receptors. (4) To examine rats with extensive unilateral lesions of the nigrostriatal DA pathway in order to determine how the distribution and morphology of D1- or D2 - immunoreactive processes is altered. We hypothesize that changes in the distribution and/or expression of DA receptors will reflect a greater degree of non-synaptic transmission and will be detectable as alterations in receptor-expressing cellular elements and their synaptic relationships. A thorough and unbiased quantitative measurement of DA receptor distribution is essential for statistically meaningful analyses of these issues and interpretation of their implications basic DA function and pathology of the basal ganglia.
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0.936 |
2003 — 2006 |
Sesack, Susan |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Acquisition of a Biological Electron Microscope and Digital Camera System @ University of Pittsburgh
A grant has been awarded to the University of Pittsburgh under the direction of Dr. Susan R. Sesack to fund the purchase of a biological electron microscope with a digital photography system and external monitor. This instrumentation will enable faculty in the Departments of Neuroscience, Biological Sciences and Chemistry to achieve and expand their research objectives by providing a state-of-the-art electron microscope system that is designed to enhance the efficiency and productivity of analyzing complex biological specimens and to capture images in a digital format. For all biologically-based sciences, knowledge regarding the fine structural details of organisms is essential for understanding their function, and the awarded electron microscope will be a principal means for visualizing this ultrastructure. The instrumentation will also be used to determine how structure is altered by environmental manipulations that drive adaptive responses. Moreover, ultrastructural methods will be combined with other techniques to determine the shape, distribution and trafficking of molecules that are essential for biological functions. Finally, the digital format of the system will considerably increase the efficiency of image capture and reproduction and greatly enhance the training missions of faculty in the natural sciences.
The faculty supported by this award are distributed across multiple departments, and so the instrumentation will support research programs that are quite diverse. A brief listing includes: ultrastructural investigation of synaptic connections that link brain regions regulating behavior, cellular processes and plasticity underlying neuronal signaling, localization of molecules regulating neurotransmission, microanalytical monitoring of brain neurochemicals, biochemical processes of muscle, synthesis and assembly of cellular organelles, intracellular molecular trafficking of proteins, synthesis, assembly and structure of proteins and bacterial viruses, assembly and segregation of chromosomes, and the molecular biology of mycobacteria and DNA tumor viruses. In the process of conducting this research, the faculty will integrate their experimental studies involving the instrumentation with the training of new scientists at the postdoctoral, doctoral, undergraduate, and high school levels. The digital format for image capture will be particularly instrumental in training, because it will provide external viewing of specimens by faculty and students working together. The instrumentation will also be used to teach courses in cell biology and virology.
The scientific importance of this project stems from the fact that it provides instrumentation that will facilitate the research programs of a large number of well-established investigators whose work is designed to improve understanding of the basic structure and function of biological organisms ranging from viruses to humans and including both normal and diseased cellular processes. The academic applications of the instrumentation will facilitate both the recruitment and education of new scientists from both traditionally represented and underrepresented groups. Such educational objectives will ensure that students of science enter society with a better appreciation of biological structure and function and a conviction that more research is needed to understand all living organisms, the environment, and the inner workings of the human body and brain. Finally, the instrumentation will enhance the infrastructure that integrates research and teaching, foster collaborations within and across scientific disciplines (e.g., chemistry, biology, and neuroscience), and contribute to the broad dissemination of the intellectual benefits of ultrastructural research within the scientific and lay communities.
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0.915 |
2004 — 2008 |
Sesack, Susan R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Afferent Regulation of Vta Dopamine Neuron Populations @ University of Pittsburgh At Pittsburgh
DESCRIPTION (provided by applicant): Dopamine (DA) neurons in the midbrain ventral tegmental area (VTA) provide a critical modulation of limbic striatal and cortical targets that facilitates appropriate motor control, approach behaviors, motivation and cognition. Deficits in these forebrain dopamine systems are associated with mental health disorders such as schizophrenia, depression, attention deficit hyperactivity disorder and substance abuse. Hence, it is important to gain a clear understanding of how DA neuron activity is itself regulated. DA neurons fire tonically via pacemaker potentials, but important signals regarding future expectancy are generated by bursts and pauses in the activity pattern that are mediated by afferent drive. In our prior research, we examined excitatory afferents to VTA DA neurons from the prefrontal cortex. We discovered a surprising degree of specificity in these connections, in that prefrontal cortical afferents synapsed only onto DA neurons projecting back to the prefrontal cortex and not onto the more numerous DA cell population projecting to the nucleus accumbens. In the present proposal, we wish to address the likelihood of additional specificity in other synaptic inputs to these same DA neuron populations in the VTA that correlate with their activity levels and functions. This goal will be accomplished through the following five specific aims. We will examine both mesoprefrontal and mesoaccumbens DA neurons specifically for (1) their general excitatory and inhibitory drive as identified by glutamate and GABA in synaptic inputs, (2) specific excitatory afferents from the brainstem laterodorsal and pedunculopontine tegmentum, (3) extrinsically derived inhibitory afferents from the nucleus accumbens, (4) intrinsically derived inhibitory synapses from GABA neurons within the VTA, and (5) mixed/modulatory afferents from the lateral hypothalamus. Evidence consistent with selective afferent drive to different populations of DA neurons will provide valuable insight into the function of each cell group and the contributions they make to normal and abnormal behaviors. Evidence for selectivity in these afferents also has important implications for the development of specific pharmacological treatments for mental health disorders that involve these populations.
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0.936 |
2007 — 2011 |
Sesack, Susan R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Factors Regulating NE Transporter Localization in Pfc @ University of Pittsburgh At Pittsburgh
[unreadable] DESCRIPTION (provided by applicant): The norepinephrine (NE) innervation to the prefrontal cortex (RFC) is involved in complex cognitive functioning, and pathologies in this system are implicated in mental health disorders including depression, post-traumatic stress disorder, and attention deficit hyperactivity disorder. NE transmission in the RFC is regulated in part by uptake through its plasma membrane transporter (NET). In the first ultrastructural immunocytochemical study of its type, we showed that most NE terminals in the RFC of naive rats contain NET primarily within the cytoplasm (i.e. not on the membrane) and lack detectable levels of the synthetic enzyme tyrosine hydroxylase (TH). Only a minority of NE terminals express appreciable plasmalemmal NET and detectable levels of TH. The basis for the predominantly cytoplasmic localization of NET and lack of TH in the majority of RFC NE terminals is not known. However, we hypothesize that these factors are influenced by the level of activity in the NE system as well as the availability of extracellular dopamine (DA), a precursor for NE. In support of this hypothesis, we have demonstrated that exposure to chronic cold stress, a treatment that persistently activates the locus coeruleus (LC) NE system, increases both the plasmalemmal localization of NET and the expression of detectable TH within the RFC. In the proposed functional anatomical studies, we will further examine the factors that regulate the subcellular distribution of NET and expression of TH in the rat RFC using immunocytochemistry and electron microscopic analysis. In Aim 1, we will study the effects of acutely altering the activity of the LC and its RFC projections using electrical or pharmacological stimulation. In Aims 2 and 3, we will examine the impact of chronic treatment with antidepressant drugs that selectively block NET, both in naive rats (Aim 2) and in animals simultaneously exposed to chronic cold stress. Finally, given the known ability of NET to transport DA, we hypothesize that NE terminals in the RFC utilize extracellular DA to synthesize NE in the absence of TH. Hence, in Aim 4, we will examine how the availability of extracellular DA affects NET distribution and TH expression in RFC NE terminals by lesioning the DA cell bodies in the ventral tegmental area. The findings from these studies will provide valuable information regarding the normal functions of the central NE system and its role in the pathophysiology and treatment of mental disorders. [unreadable] [unreadable] [unreadable]
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0.936 |
2007 — 2008 |
Sesack, Susan R |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Persistent Impact of Developmental Nicotine On Cholinergic Input to Da Cells @ University of Pittsburgh At Pittsburgh
[unreadable] DESCRIPTION (provided by applicant): More then 17% of pregnant women in the USA smoke and/or use nicotine replacement therapies. Although tobacco contains many harmful substances, nicotine not only underlies the addictiveness of tobacco consumption, it also has neurotoxic and neuroteratogenic effects on the developing brain. In animal models, exposure to nicotine during early development provokes behavioral deficits in offspring that resemble those reported in children after maternal nicotine consumption. Such behavioral impairments, most notably hyperlocomotor activity, are compellingly consistent with malfunctioning of the midbrain dopamine system and its cholinergic innervation, for which nicotine is an agonist. However, no studies to date have examined whether developmental nicotine induces structural alterations in these two cell groups that persist into adulthood. The central hypothesis guiding this proposal is that long-term behavioral impairments following nicotine exposure at particular developmental stages result from underlying morphological alterations of the brainstem dopamine and cholinergic systems. To test this hypothesis using light and electron microscopy, we will conduct the first unbiased stereological assessments of brainstem neurons in adult rats treated with nicotine prenatally or in the early postnatal period, which correspond approximately to the first and second halves of human pregnancy. We will also examine the cholinergic axons communicating between the mesopontine tegmentum (MP) and dopamine cells in the ventral tegmental area (VTA) as well as total excitatory and inhibitory synapses. In Aim 1, we will determine the persitent structural consequences of nicotine exposure during E4-E21 on the VTA and/or MP of adult animals. Aim 2 will examine the persistent structural consequences of nicoitne exposure during P1-P14 on the VTA and/or MP of adult animals. For both aims, we will measure a comprehensive set of cellular and phenotypic parameters in both the VTA and MP and will correlate anatomical measurements with behavioral assessments of locomotor activity in individual animals. The outcome of the proposed studies will allow specific predictions regarding changes in the human brain following prenatal nicotine exposure and facilitate the development of medical treatment strategies for the offspring of smokers by demonstrating the morphological impact on the brain regions that are most likely to be primarily and persistently affected. Pregnant women who smoke or who use nicotine replacement therapy during pregnancy expose their infants to neuroteratogenic effects of nicotine that can result in learning disabilities and behavioral abnormalities. This proposal uses an animal model of early nicotine exposure to examine structural damage in the brain regions that regulate cognitive function, motivated behaviors, and liability for later addiction. The data obtained in these studies will facilitate the development of medical treatment strategies for the children of smokers by revealing the brain regions that are most fundamentally affected by early nicotine exposure. [unreadable] [unreadable] [unreadable]
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0.936 |