Thomas J. Gould - US grants

Aging produces deficits in cerebellar noradrenergic function and associated motor learning. Because the elderly are more susceptible to falls, it is desirable that motor systems remain highly functional with age. Declines in motor learning are associated with declines in cerebellar beta-adrenergic signal transduction. Therefore it is important to understand the mechanisms that produce this noradrenergic deficit. A key issue in research of aging is whether oxidative stress is major factor in age-related deficits. Initial studies suggest yes. A unique approach to this critical issue is to use rats that have been bred for the trait of resistance to normobaric hyperoxia. In young control rats, exposure to hyperoxia induce deficits in cerebellar beta- adrenergic function similar to deficits seen in aged rats. The hyperoxia resistant rats, however, do not show this deficit. More interesting, cerebellar beta-adrenergic function in aged hyperoxia resistant rats is not deficient. This is in stark contrast to age- matched controls. Thus, normobaric hyperoxia is a model of aging that can induce oxidative damage in the cerebellar beta-adrenergic signal transduction cascade and hyperoxia resistant rats provide a unique opportunity to study the role of oxidative stress in aging. Three important questions addressed here are 1) Does hyperoxia affect certain proteins in the beta-adrenergic signal transduction cascade? 2) Are hyperoxia resistant rat resistant to in vitro oxidative stress? 3) Will aged hyperoxia resistant rats retain high levels of motor learning? The first experiment uses a model of aging (i.e., hyperoxia) that allows in vitro intracellular study of the effects of oxidative stres on the cerebellar beta-adrenergic signal transduction cascade. The second experiment tests if hyperoxia resistant rats ar immune to hydroxyl and/or superoxide radical-induced damage. Cerebellar tissue from control and hyperoxia resistant rats will be incubated in hydrogen peroxide to generate hydroxyl radicals or in dihydroxyfumarate to generate superoxide. Intracellular assessment of cerevellar beta- adrenergic function will be made and dose response curves for oxidants will be compared between groups. Exposure to hyperoxia and oxzidants has been demonstrated to generate damage similar to age-related damage. Finally, in young rats cerebellar beta-adrenergic function is positively correlated with motor learning. The third experiment investigates if aged hyperoxia resistant rats have a high level of motor learning that correlates with a functional cerebellar beta- adrenergic system. In sum, these experiments are initial steps in understanding of both the effects of oxidative stress and whether oxidative stress is a major playeer in age-related deficits.

Research over the past two decades has revealed that a wide variety of animal species, including fish, birds, non-human mammals and humans, share a powerful sensitivity to the geometric properties of enclosing spaces (e.g., the relative length of walls defining enclosures). They use such information to reestablish spatial orientation after being disoriented (Cheng, 1986; Hermer & Spelke, 1996; for a review, see Cheng & Newcombe, in press). Further, it has been suggested that such geometric processing constitutes a specialized cognitive module that is normally impenetrable to nongeometric information (Cheng, 1986; Hermer & Spelke, 1996), with combination of information only made possible by use of language (Spelke & Hermer, 1996). These findings on geometric processing and its purported modularity have been exciting to a wide audience of researchers focused on cognitive architecture, comparative cognition, cognitive development, and the role of language in behavior. They are relevant to the hotly-debated issues concerning the extent to which knowledge is innate or environmentally plastic. Parents, educators and policy makers have a stake in accurate understanding of the nature of development.

Vital issues concerning these proposals remain unsettled, however. This research will address controversy in two areas. First, the nature of geometric sensitivity is not yet clear. We will address two questions: how geometric coding is related to representations of viewer position, and whether information about the lengths of the sides of a space is retained in an absolute way (as some mental equivalent of a measured distance) or in a relative fashion (as some lengths being simply longer or shorter than others). Second, there is doubt about the claim that geometric information is encapsulated and the associated idea that landmarks are not integrated with geometric information unless language is used to link cognitive modules. An alternative account holds that geometric and featural information are normally integrated in a way that depends on the relative usefulness of various kinds of information in particular situations. This research project will contrast these accounts.

[unreadable] DESCRIPTION (provided by applicant): In 1988, the US Surgeon General concluded that tobacco products are addictive and nicotine is the main pharmacological agent in tobacco responsible for tobacco's addictive nature. Despite over whelming evidence of the adverse health effects of smoking, it is estimated that 68.8 million Americans use tobacco products and 400,000 tobacco-related deaths occur in the United States each year. However, it is not completely understood why nicotine is addictive. One reason for this incomplete understanding of nicotine addiction may be that addiction is a complex disorder with many factors contributing to the disease. Possible factors that may contribute to nicotine addiction include genetics and learning. Many studies suggest that nicotine enhances learning. Specifically, the limbic area of the brain is involved in both learning and addiction and thus nicotine effects on this area may mediate cognitive influences on addiction. It is the hypothesis of this proposal that nicotine alters the function of the hippocampus during learning, producing a learned state that is different from learning in the absence of the drug, and that this learning may involve different patterns of cell signaling and gene activation than those activated during comparable learning without drug. The ability of nicotine to enhance learning processes may facilitate addiction by contributing to drug-context associations that could precipitate craving and relapse. In support of this, nicotine has been shown to enhance a long-lasting form of contextual fear conditioning, a type of classical conditioning that involves the hippocampus. Long-term memory storage is known to involve alteration in gene expression, and the proteins encoded by these induced genes, such as MAP kinases, result in long-lasting changes in neuronal function. Nicotine can also alter activation of MAP kinases. Proposed experiment will identify the nicotinic acetylcholinergic receptor subtypes, identify the neural site of action, and identify MAP kinases involved in the long-lasting enhancement of contextual fear conditioning by nicotine. Investigating the effects of nicotine on learning from the level of receptor activation to changes in cell signaling will enhance understanding of addiction and aid in development of treatments for nicotine addiction [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Numerous studies have shown alcohol and nicotine use are correlated. Further, it has also been shown that smoking is a strong predictor for transitioning from social to problem drinking in adolescents. The reasons why alcohol and nicotine are commonly used together, however, are not completely understood and may involve multiple factors. It is possible that the co-use of alcohol with nicotine may be appealing because nicotine use during alcohol consumption may decrease some of the negative effects of alcohol such as disrupted cognition. The hippocampus is one structure involved in learning that seems particularly sensitive to the disruptive effects of ethanol. For instance, learning the context of an event, a task that is dependent on the hippocampus, is disrupted by ethanol administration in rats and mice. Preliminary findings, however, suggest that nicotine can reverse this deficit. Thus, this ability of nicotine to reduce negative effects of ethanol could facilitate greater or repeated alcohol consumption. This could facilitate a transition in drinking patterns. In addition, repeated nicotine use could also lead to nicotine addiction. It is a hypothesis of this proposal that nicotine will prevent ethanol-induced deficits in contextual conditioning in C57BL/6 mice and that the hippocampus is a neural site were nicotine works to reduce ethanol-associated learning deficits by altering the cellular processes disrupted by ethanol. As an initial step in investigating the interactive effects of nicotine on alcohol use, this proposal will examine the effects of ethanol and nicotine co-administration on hippocampus-dependent learning and also examine the neurobiology that supports ethanol-nicotine interaction. Understanding why nicotine and ethanol are co-used will aid in understanding factors that influence shifts in drinking patterns and nicotine use. Understanding the underlying neurobiology will not only further aid in this understanding but will also aid in developing treatments for alcoholism and nicotine addiction. [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Tobacco use is a serious health problem in the United States: over 435,000 deaths each year are attributed to smoking, and although 42% of smokers attempt to quit each year, less than 6% are successful. These statistics suggest that current smoking cessation treatments are not adequate. One motivating factor that may contribute to both the maintenance of nicotine addiction and relapse is nicotine withdrawal effects. Withdrawal symptoms reported by smokers include insomnia, increased appetite, affective changes, and cognitive deficits. In fact, changes in cognition during abstinence predict relapse; suggesting that understanding the neural and genetic substrates underlying these changes could facilitate development of more efficacious treatments. Great advances have been made in understanding nicotine addiction but there are serious gaps in our knowledge of nicotine withdrawal. For instance, examination of the neurobiological substrates of nicotine withdrawal disruption of cognitive processes is limited and examination of genetic influences is nonexistent. A goal of this proposal is to identify the genetic and neurobiological substrates of nicotine withdrawal deficits in contextual conditioning, a cognitive process. This proposal will use traditional behavioral genetic techniques and genetically modified mice to achieve this goal. Characterizing the dynamics of nicotine withdrawal will further understanding of nicotine addiction and aid in understanding the relationship between the behavioral effects of nicotine and changes in receptor function and downstream processes. Identification of the genetic and neural substrates of nicotine withdrawal will aid development of new treatments for nicotine withdrawal symptoms and in the tailoring of treatments to produce the most effective results. In studies of smokers, it is clear that changes in cognitive processes during abstinence are an important component of nicotine withdrawal. One thing that is striking when examining the literature on animal models of withdrawal is the dearth of information on the genetic and neural substrates of nicotine withdrawal deficits in cognitive processes. This proposal will examine the pharmacology, the neurobiology, and the genetics of nicotine withdrawal disruption of contextual learning in mice. Identifying neurobiological and genetics factors that contribute to the effects of nicotine is important for understanding nicotine addiction and for developing novel treatments that could potentially be tailored by genotype to provide the most effective treatment. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Tobacco use is a serious health problem in the United States: over 435,000 deaths each year are attributed to smoking, and although 42% of smokers attempt to quit each year, less than 6% are successful. These statistics suggest that current smoking cessation treatments are not adequate. One motivating factor that may contribute to both the maintenance of nicotine addiction and relapse is nicotine withdrawal effects. Withdrawal symptoms reported by smokers include insomnia, increased appetite, affective changes, and cognitive deficits. In fact, changes in cognition during abstinence predict relapse; suggesting that understanding the neural and genetic substrates underlying these changes could facilitate development of more efficacious treatments. Great advances have been made in understanding nicotine addiction but there are serious gaps in our knowledge of nicotine withdrawal. For instance, examination of the neurobiological substrates of nicotine withdrawal disruption of cognitive processes is limited and examination of genetic influences is nonexistent. A goal of this proposal is to identify the genetic and neurobiological substrates of nicotine withdrawal deficits in contextual conditioning, a cognitive process. This proposal will use traditional behavioral genetic techniques and genetically modified mice to achieve this goal. Characterizing the dynamics of nicotine withdrawal will further understanding of nicotine addiction and aid in understanding the relationship between the behavioral effects of nicotine and changes in receptor function and downstream processes. Identification of the genetic and neural substrates of nicotine withdrawal will aid development of new treatments for nicotine withdrawal symptoms and in the tailoring of treatments to produce the most effective results. In studies of smokers, it is clear that changes in cognitive processes during abstinence are an important component of nicotine withdrawal. One thing that is striking when examining the literature on animal models of withdrawal is the dearth of information on the genetic and neural substrates of nicotine withdrawal deficits in cognitive processes. This proposal will examine the pharmacology, the neurobiology, and the genetics of nicotine withdrawal disruption of contextual learning in mice. Identifying neurobiological and genetics factors that contribute to the effects of nicotine is important for understanding nicotine addiction and for developing novel treatments that could potentially be tailored by genotype to provide the most effective treatment.

DESCRIPTION (provided by applicant): In 1988, the US Surgeon General concluded that tobacco products are addictive and nicotine is the main pharmacological agent in tobacco responsible for tobacco's addictive nature. Despite overwhelming evidence of the adverse health effects of smoking, it is estimated that 68.8 million Americans use tobacco products and 400,000 tobacco-related deaths occur in the United States each year. However, it is not completely understood why nicotine is addictive. One reason for this incomplete understanding of nicotine addiction may be that addiction is a complex disorder with many factors contributing to the disease. Possible factors that may contribute to nicotine addiction include long-lasting change in learning and long-lasting changes in the synaptic plasticity that underlies learning. Studies suggest that initially nicotine enhances learning but with continued use tolerance develops and deficits in learning emerge when administration ceases. The limbic area of the brain is involved in both learning and addiction and thus the effects of nicotine in this area may mediate cognitive influences on addiction. It is the hypothesis of this proposal that nicotine alters the function of the hippocampus during learning, producing a learned state that is different from learning in the absence of the drug, and that this learning may involve different patterns of cell signaling and gene activation than those activated during comparable learning without drug. The ability of nicotine to alter learning processes and the underlying neural function may facilitate addiction by contributing to withdrawal-related deficits in learning and the formation of long-lasting drug-associated memories that could precipitate craving and relapse even after long periods of abstinence. In support of this, acute nicotine has been shown to enhance a long-lasting form of contextual fear conditioning, a type of classical conditioning that involves the hippocampus but withdrawal from chronic nicotine disrupts this learning. Long-term memory storage is known to involve alteration in gene expression, and the proteins encoded by these induced genes, such as mitogen activate protein kinases (MAPK), result in long-lasting changes in neuronal function; recent evidence suggests that nicotine and learning interact to alter signaling through the MAPK pathway. Proposed experiments will identify the neural substrates that underlie the effects of nicotine on hippocampus-dependent learning, identify the specific role of hippocampal subregions in the effects of nicotine on learning, and identify the downstream targets of MAPK mediating the changes in synaptic plasticity involved in the effects of nicotine on learning. Investigating the effects of nicotine on learning from the behavioral level to changes in cell signaling will enhance understanding of addiction and aid in therapeutic development for nicotine addiction.

? DESCRIPTION (provided by applicant): Nicotine addiction continues to be a major problem in the US with smoking accounting for the loss of 443,000 lives and an estimated $193 billion economic burden each year. These staggering statistics speak to important of identifying factors that contribute to nicotine addiction. Cognitive deficits such as disrupted learning are a major symptom of nicotine withdrawal, yet little is understood about the genetic factors that contribute to nicotine withdrawal-related changes in cognition. Identifying the neural and genetic substrates of nicotine withdrawal deficits in cognition will provide data to facilitate drug discovery and identify markers for at risk populations. Use of genetic data to identify at risk populations could also facilitate development of treatments that could increase the likelihood of maintaining abstinence. Recent data from a study examining nicotine withdrawal-related changes in hippocampus-dependent learning in mice demonstrated that genetics contributes to this cognitive withdrawal phenotype. As the specific genes involved in this withdrawal phenotype are unknown, it is the goal of this application to use next-generation sequencing to identify gene variants related to nicotine withdrawal deficits in learning. Studies in the proposal will use the recombinant inbred (RI) BXD strain to characterize phenotypic differences across BXD lines (Aim 1) and use that data for quantitative trait loci (QTL) analysis to identify genes associated with the nicotine withdrawal learning deficit phenotype (Aim 2). In addition, BXD databases will be examined to identify other phenotypes that are genetically correlated with the cognitive withdrawal phenotype (Aim 2). Finally, RNA-sequencing in BXD lines that show extreme phenotypic variation will be used to identify changes in the transcriptome associated with the nicotine withdrawal deficit in learning phenotype. These studies should significantly advance understanding of and treatment of nicotine addiction. Identifying genes and gene expression changes that are associated with nicotine withdrawal deficits in learning in the mouse will facilitate identifying if homologous genes in humans that are associated with nicotine withdrawal deficits in cognition. This could help practitioners tailor treatments to patients. In addition, identifying specific changes in the transcriptome associated with nicotine withdrawal deficits in learning will provide valuable information on the changes in cell signaling that contribute to nicotine withdrawal deficits in learning and this should aid in identifying potential targets for pharmacotherapeutic development.

PROJECT SUMMARY Adolescent smoking is a serious public health concern. Earlier initiation of smoking is a key factor in the development of nicotine dependence and associated mental health problems. Increasing evidence suggests that nicotine exposure during this critical period of development may have long-term cognitive consequences. Mouse models represent an important tool for identifying neural and genetic underpinnings of behavioral response to nicotine exposure across development, permitting experimental control over time course and genetic factors. The primary objective of this proposal is to identify sex and strain variability in long-term cognitive effects of adolescent nicotine exposure. We previously identified that adolescent C57BL/6J male mice exposed to nicotine display long-term cognitive deficits, as assessed by contextual fear conditioning, during adulthood. However, the effect of genetics (i.e. strain) and sex on these long-term consequences of adolescent nicotine exposure have not yet been investigated. Here, we aim to determine the interstrain variability in long-term cognitive effects of adolescent nicotine exposure in the founder strains of the Collaborative Cross (CC), a panel of recombinant inbred lines derived from eight genetically diverse inbred strains: five classical inbred strains (A/J, C57BL/6J, 129S1/SvImJ, NOD/ShiLtJ, NZO/HlLtJ) and three wild-derived strains (CAST/EiJ, PWK/PhJ, WSB/EiJ). The CC panel represents far greater genetic diversity than previous recombinant inbred panels, and thus, represents an unprecedented opportunity for genetic analyses. Additionally, sex differences exist in smoking behaviors and the impact of smoking on cognition; therefore both male and female mice from each strain will be examined to identify sex effects and interactions with strain. Studies in this proposal will use the founders of the CC to characterize phenotypic differences across inbred strains (Aim 1) and to investigate sex differences within and across strains (Aim 2). The goal of this proposal is to demonstrate feasibility of using the CC panel for a forward genetics mapping study of the long-term detrimental effects of adolescent nicotine exposure. This proposal represents an important step in investigating an understudied area of the genetic underpinnings of the long-term consequences of adolescent nicotine exposure. Ultimately, investigating the genetic and neurobiological factors that underlie susceptibility to these long-term consequences may aid in the development of preventative treatments.