Edward D. Levin - US grants

The goal of this research is to elucidate the mechanisms by which dopaminergic (DA) and cholinergic (ACh) neurotransmitter systems interact in the neural bases of cognitive function. In previous studies, Dr. Levin has documented the interactions of DA and ACh drugs given systemically. The current proposal is to investigate critical neural pathways which underlie these DA-ACh interactions. Sites to be studied are those which are important for cognitive function and where DA and ACh systems are anatomically connected. These include the septal nucleus, the nucleus basalis and the ventral tegmental area. These studies will help achieve the goal of elucidating basic mechanisms of DA-ACh interactions in cognitive behavior. This is important to further develop basic understanding of the neural bases of cognitive function. Since no neural system acts alone, it is important to understand how they act together.//

DESCRIPTION: (Applicant's Abstract) Chronic nicotine infusion in rats has been found in our studies with the radial-arm maze to improve working memory function. This type of chronic nicotine infusion models that achieved by the nicotine skin patch, an increasingly common way to administer nicotine which has been found in our studies to effectively improve cognitive function in schizophrenics, Alzheimer's disease patients and adults with attention deficit disorder. The proposed studies will help determine the critical neural systems underlying chronic nicotine infusion-induced memory improvement. The primary hypothesis is that nicotinic receptors in the hippocampus are critical for the nicotine infusion effect on memory. We have found that ibotenic acid lesions of neurons in the ventral hippocampus eliminates the effectiveness of chronic nicotine for improving memory. Also we have found that local ventral hippocampal infusion of the nicotinic antagonists mecamylamine, DH-beta-E and MLA cause significant deficits in working memory. MLA effectively blocks alpha-7 receptors, DH-beta-E effectively blocks alpha-3 beta-4 receptors and mecamylamine effectively blocks alpha-3 beta-4 receptors all of which are found in the hippocampus. These three nicotinic antagonists will be infused either during the development of the chronic nicotine effect or during its expression to determine the involvement of these nicotinic receptors in different phases of the chronic nicotine effect on memory. In the later phases of the project similar studies will be carried out in other brain areas including the dorsal hippocampus, medial and lateral frontal cortex, nucleus accumbens and the midbrain dopaminergic nuclei. This will further complete our analysis of the neural bases for chronic nicotine effects on memory. These studies will further our understanding of the neural systems underlying cognitive function and dysfunction. This will be of critical importance for the development of nicotinic-based therapeutics for cognitive dysfunction.

DESCRIPTION: Applicant's Abstract Drug abuse cannot be explained merely as a result of reward provided by increasing dopamine efflux in the nucleus accumbens. Other neurobehavioral systems such as neurocognitive function play important roles in the development and consequence of drug abuse. Drugs of abuse the have been shown to have robust effects on attentional processes. Attentional effects are important not only for understanding negative outcomes of drug abuse, but also for understanding the reasons why people take these drugs and basic mechanisms of addiction. The Behavioral Toxicology Society would like to conduct a symposium within its annual meeting May 1-2, 1999 in Research Triangle Park, NC entitled "Attention as a Target of Intoxication: Insights and Methods from Studies of Drug Abuse." This symposium will bring together leaders in the field to discuss both methods for assessing attention in rodents, non-human primates and humans, as well as latest results concerning the interactions of drugs of abuse and attentional processes. The first session of the symposium will focus on methodological and theoretical issues concerning attentional assessment in rodents. This will take place in the context of the negative effects of intoxication on attentional function. Dr. Strupp will address the persistent negative attentional effects of prenatal cocaine exposure in rats. Dr. Bushnell will address the adverse attentional effects of current exposure to solvent inhalation and benzodiazepines. Dr. Sarter will discuss the role of the basal forebrain in the effects of drugs of abuse on attention. The second session will focus on a single drug nicotine, addressing issues of interspecies extrapolation in Dr. Marrocco's talk, self-medication in Dr. Levin's talk and the interaction of effects on attention and arousal in Dr. Wartburton's talk. These methodological and theoretical issues will be integrated in the context of each talk as well as in a discussion session at the end of the symposium. This symposium will provide the latest information concerning techniques of attentional assessment and the effects of drugs of abuse to an audience of research scientists in the field of behavioral toxicology. Bringing these methods and the intellectual resources of the scientists in this field to study attention and drug abuse will considerably advance the scope of understanding of the neurobehavioral basis and consequences of drug addiction.

DESCRIPTION (provided by applicant) The Behavioral Toxicology Society (BTS) would like to conduct a symposium within its annual meeting April 21-22, 2002 in Research Triangle Park, NC, entitled "Behavioral Genetics and Toxic Response." This symposium will provide the latest information concerning the use of genetic models to discover mechanisms of toxicant action on behavioral function. Research concerning the Ah receptor, nicotinic receptor, dopamine transporter and superoxide dismutase knockout mice will be presented. The speakers will include nationally renowned researchers. This symposium will provide integration of mechanistic research with animal models of behavioral function. Both the promise and pitfalls of behavioral genetic studies will be discussed, so that these methods can be intelligently used for behavioral toxicology research. The audience will be scientists active in behavioral toxicology research. Bringing these methods and the intellectual resources of the scientists in this field to study the potential interaction between toxicant exposure and genetic predisposition, this meeting will provide an opportunity for methodological and theoretical issues to be integrated in the context of each talk as well as in a discussion session at the end of the symposium.

Nicotine is self-administered via cigarette smoking by the great majority of patients with schizophrenia. Nicotine has direct effects on cognitive function and interacts with antipsychotic drugs to substantially influence their actions on cognitive function. The cognitive effects of nicotine may present a novel opportunity for improving the treatment of cognitive dysfunction associated with schizophrenia and cognitive dysfunction induced by antipsychotic drugs. Classical neuroleptics such as haloperidol and "atypical" antipsychotics such a clozapine and risperidone have substantially different mechanisms of action and likely interact with nicotine in quite different ways. The proposed project will determine the functional mechanisms by which nicotinic systems interact with antipsychotic drugs to affect cognitive function. Both classical and atypical antipsychotic drugs have been found to impair memory function. Haloperidol-induced working memory deficits have been found in our earlier studies of schizophrenic patients and laboratory rats to be reversed by acute doses of nicotine. Recently, we have found that the working memory impairment caused in rats by clozapine administration can be reversed by nicotine. These effects will be used as a forum in which to determine the critical neural mechanisms by which nicotine interacts with antipsychotic drugs in the control of memory function. We hypothesize that nicotinic receptor systems in the hippocampus are a key mechanism by which nicotine alleviates schizophrenia associated attentional impairment and antipsychotic drug-induced memory impairment. Nicotinic innervation of the hippocampus has been found in our previous studies to be critical for nicotine effects on memory. Importantly, we have also shown that hippocampal DA innervation is also important for memory function. The proposed project will specify the mechanisms underlying nicotinic interactions with antipsychotic effects on memory function, including involvement of nicotinic receptor subtypes and their anatomic loci in hippocampus important for memory function. Dose response local infusion studies with selective nicotinic antagonist subtypes will be used to determine the relationship of nicotinic systems for memory performance in the benchmark radial-arm maze task as well as an operant attention task. These basic studies will help elucidate important therapeutic issues concerning the impact of nicotinic co- treatment with classic and atypical antipsychotic drugs to improve memory and attentional function. These studies will provide information concerning neural systems likely to underlie nicotinic actions we have seen on a systemic level and facilitate the development of new drug therapies for cognitive dysfunction in schizophrenia.

DESCRIPTION (provided by applicant) The Behavioral Toxicology Society (BTS) would like to conduct a symposium within its annual meeting June 22-24, 2003 in Philadelphia, PA entitled "Marine Toxin Impacts on Neurobehavioral Function." This symposium will provide the latest information concerning the neural mechanisms of marine toxin actions on behavioral function. Research concerning the neurobehavioral mechanisms and effects of Pfiesteria toxin, domoic acid and other marine toxins will be presented. The speakers will include nationally renowned researchers. This symposium will provide integration of mechanistic research with animal models of behavioral function. Recent breakthroughs and research challenges will be discussed so that an intelligent agenda for behavioral toxicology research in the area can be devised. The audience will be scientists active in behavioral toxicology research. Bringing the intellectual resources and research methods of the scientists in this field to study the potential toxicity of marine toxins will greatly enhance our ability to characterize risks that may be posed by exposure to marine toxins. The forum will provide an opportunity for methodological and theoretical issues to be integrated in the context of each talk as well as in a discussion session at the end of the symposium.

[unreadable] DESCRIPTION (provided by applicant): The great majority of tobacco addiction begins during adolescence, but very little is known about the neurobehavioral effects of nicotine in adolescents compared to adults. Adolescents are still undergoing important neurodevelopmental changes on the path to adulthood. Nicotine exposure in adolescence may have lasting impacts on this late neurodevelopment. There are suggestions in the clinical literature that more heavily addicted smokers begin smoking earlier in adolescence, but the impact of nicotine self-administration during adolescence versus self-selection bias whereby people more prone to heavy addiction also begin earlier, cannot be ethically unconfounded in humans. This project is based on our hypothesis beginning nicotine self-administration during adolescence leads to greater nicotine intake and dependence than beginning in adulthood. Our preliminary data demonstrated in the rat model of nicotine self-administration that rats with adolescent-onset nicotine self-administration self-administer substantially higher total doses of nicotine than adult-onset rats, This higher rate of nicotine self-administration continues into adulthood with an approximate doubling of nicotine self-administration. [unreadable] [unreadable] The proposed experiments will determine the causal relationship between adolescent-onset nicotine self-administration and enhanced long-term nicotine self-administration with these Specific Aims. [unreadable] 1. Determine the pharmacokinetics and dose-effect functions of nicotine in adolescents and adult rats. [unreadable] 2. Determine the impact of nicotine replacement and nicotinic antagonist therapy on nicotine self-administration in adolescent-onset and adult-onset nicotine self-administration. [unreadable] 3. Determine the age threshold for the adult-like nicotine self-administration. [unreadable] 4. Determine if adolescent-onset nicotine self-administration enhances cocaine dependence. [unreadable] 5. Determine sex differences in adolescent-onset nicotine self-administration. Nicotine pharmacokinetic measurements in adolescent and adult rats will be used to determine the effect of altered distribution and metabolism versus pharmacodynamic factors in accounting for age-related differences in nicotine self-administration. [unreadable] [unreadable] Benefits of this research include a more relevant animal model of adolescent-onset smoking, improved understanding of how adolescent-onset nicotine use potentiates nicotine intake, a cause and effect determination of the gateway hypothesis of adolescent nicotine use leading to harder drugs and the development of better treatments for adolescent-onset nicotine dependence. [unreadable] [unreadable]

The training and education core will provide educational support for the Duke University Superfund Basic Research Center. The centerpiece will be our weekly seminar series which will feature local and national speakers of the full range of environmental and biomedical toxicology to help the students, postdocs, technicians and faculty of the center keep up with the latest research findings. By having members from all the projects attend the diverse presentations, we will foster mutual understanding of the diverse aspects of the center. With the postdoctoral program we will recruit fellows to conduct collaborative research among the different projects in the center. We will host workshops on research methods of the latest scientific techniques as well as workshops on scientific communication skills to help us effectively convey our research to our scientific colleagues and the broader society. Once a month we will have informal chalk talks in which all of the projects will in turn discuss their latest results and plans for future studies. These brainstorming sessions have been especially useful in developing new collaborations within the center. Once per semester we will host a day-long symposium on a focused area of toxicology to learn in depth the ways in which specific toxicological problems can be effectively addressed in a collaborative effort.

A variety of chemicals on the Superfund list, such as pesticides, metals and polyhalogenated hydrocarbons have been found to impair cognitive function, including learning, memory and attention. We have focused on determining the neural mechanisms underlying the cognitive impairments caused by developmental pesticide exposure. Using the classic rat model of developmental neurobehavioral toxicology, we have shown in the first funding period of this center that the organophosphate insecticide chlorpyrifos causes persistent effects on working and reference memory. We have taken a two-stage approach to determine the neural underpinnings of these effects. Neurochemical studies in the Slotkin lab have demonstrated the chlorpyrifos-induced disruptions of cholinergic, catecholaminergic and serotonergic transmitter systems. Neurobehaviorai studies in the Levin iab have demonstrated with pharmacoiogicai probes that developmental chlorpyrifos exposure disrupts the functional role played by muscarinic acetylcholine systems in memory function. We extended study of developmental chlorpyrifos effects on cognitive function to zebrafish to better understand the molecular effects underlying this impairment. We found with zebrafish that chlorpyrifos exposure during development causes persisting cognitive impairment. Initial studies with morpholino suppression of acetylcholinesterase show cognitive impairments in zebrafish. These studies will determine the neural mechanisms underlying ehlorpyrifos-induced effects on learning, attention and emotional response. Specific tests of learning (repeated acquisition), attention (operant signal detection) and anxiety (elevated plus maze) will be used together with pharmacological probes of choliriergic, catecholaminergic and serotonergic transmitter receptor systems to determine not only the impact of chlorpyrifos on these neurobehavioral functions but alto to determine the functional role of these transmitter systems in the persisting neurobehavioral effects of chlorpyrifos. Initial studies will be made oncerning the specificity of these effects to chlorpyrifos or generality to other organophosphate pesticides. Zebrafish studies will provide critical information of how pesticides affect molecular controls over cognitive development.

A variety of chemicals on the Superfund list, such as pesticides, metals and polyhalogenated hydrocarbons have been found to impair cognitive function, including learning, memory and attention. We have focused on determining the neural mechanisms underlying the cognitive impairments caused by developmental pesticide exposure. Using the classic rat model of developmental neurobehavioral toxicology, we have shown in the first funding period of this center that the organophosphate insecticide chlorpyrifos causes persistent effects on working and reference memory. We have taken a two-stage approach to determine the neural underpinnings of these effects. Neurochemical studies in the Slotkin lab have demonstrated the chlorpyrifos-induced disruptions of cholinergic, catecholaminergic and serotonergic transmitter systems. Neurobehaviorai studies in the Levin iab have demonstrated with pharmacoiogicai probes that developmental chlorpyrifos exposure disrupts the functional role played by muscarinic acetylcholine systems in memory function. We extended study of developmental chlorpyrifos effects on cognitive function to zebrafish to better understand the molecular effects underlying this impairment. We found with zebrafish that chlorpyrifos exposure during development causes persisting cognitive impairment. Initial studies with morpholino suppression of acetylcholinesterase show cognitive impairments in zebrafish. These studies will determine the neural mechanisms underlying ehlorpyrifos-induced effects on learning, attention and emotional response. Specific tests of learning (repeated acquisition), attention (operant signal detection) and anxiety (elevated plus maze) will be used together with pharmacological probes of choliriergic, catecholaminergic and serotonergic transmitter receptor systems to determine not only the impact of chlorpyrifos on these neurobehavioral functions but alto to determine the functional role of these transmitter systems in the persisting neurobehavioral effects of chlorpyrifos. Initial studies will be made oncerning the specificity of these effects to chlorpyrifos or generality to other organophosphate pesticides. Zebrafish studies will provide critical information of how pesticides affect molecular controls over cognitive development.

DESCRIPTION (provided by applicant): The purpose of the Neurobehavioral Teratology Society (NBTS) is to foster the science of determining the neural mechanisms and persisting behavioral consequences of developmental exposure to toxicants. Our annual meeting (this is the 34th) is held for all in the field to communicate their latest research findings to their colleagues for continuing education and critical evaluation and to provide a forum for discussion of the current progress and directions for the future. NBTS would like to conduct a symposium with its annual meeting June 22-24, 2010 in Louisville, KY entitled "Complementary Zebrafish Models for Neurobehavioral Teratology Research: Opportunities and Challenges." This symposium will provide the latest information concerning the use of zebrafish models as complementary models for developmental neurobehavioral toxicology research. The speakers will include nationally renowned researchers. This symposium will provide integration of mechanistic research with animal models of neurobehavioral function. The proposed speakers for the symposium are Edward Levin, Duke University Medical Center, Robert Gerlai, University of Toronto, Lori White, Rutgers University, Frank Scalzo, Bard College, Stephanie Padilla, US- Environmental Protection Agency, and Robert Tanguay, Oregon State University. Recent breakthroughs and research challenges will be discussed so that an intelligent agenda for neurobehavioral toxicology research in the area can be devised. The audience will be scientists active in developmental neurobehavioral toxicology research. Bringing the intellectual resources and research methods of the scientists in this field to use zebrafish models will greatly enhance our ability to characterize risks that may be posed by exposure to environmental toxicants. The forum will provide an opportunity for methodological and theoretical issues to be integrated in the context of each talk as well as in a discussion session. Funding is needed for meeting logistical support, travel, costs of the venue and accommodations. Importantly, for continuing progress we ask for support of students and post-doctoral trainees to participate in the meeting. PUBLIC HEALTH RELEVANCE: The symposium entitled "Complementary Zebrafish Models for Neurobehavioral Teratology Research: Opportunities and Challenges" will be held in the annual meeting of the Neurobehavioral Teratology Society (NBTS) annual meeting June 22-24, 2010 in Louisville, KY. This symposium will provide the attendees the latest information about the usefulness of the zebrafish model for mechanistic and screening studies concerning developmental neurobehavioral toxicity. This is a timely symposium to convey important information about this emerging complementary research model for neurobehavioral teratology.

Nicotine intake constitutes a principal mechanism for tobacco addiction. Adequate treatment of smoking addiction remains problematic. Part of the problem with devising effective treatment is a poor understanding of the pharmacologic aspects of nicotine that underlie addiction. In addition to activating nicotinic acetylcholine receptors, nicotine also causes pronounced receptor desensitization. It is not currently known how much of each of nicotine's two actions at the receptor level - stimulation vs. desensitization, contribute to its particular behavioral effects, including reinforcement and addiction. Sazetidine-A is a novel compound that provides potent desensitization of a4B2 nicotinic receptors. Our preliminary studies have shown the promise of sazetidine-A. We have shown that Sazetidine-A significantly reduces nicotine self-administration both with acute and chronic administration. The proposed neurobehavioral studies will broaden the sazetidine-A characterization, determining the dose and time-effect function at which the maximum efficacy in reducing extended access nicotine self-administration is reached and the doses at which side effects are seen. Sex-differences in response will be determined in all phases of the study. Sazetidine-A efficacy in reducing relapse to nicotine self-administration with challenges of nicotine priming, conditioned cues and stress will be determined. Newly developed compounds in the Sazetidine class of nicotinic desensitizing agents will be screened for blockade of nicotine-induced sensitization of locomotor hyperactivity. Those compounds and doses effective in this screen will be tested for efficacy in significantly reducing nicotine self-administration and helping to prevent relapse. The intended beneficial outcome of this research is to determine the most effective way to use nicotinic desensitizing agents to reduce dependence on tobacco and facilitate cessation.

The preclinical project, Adaptive Therapeutics Development in Rat Models, will determine the efficacy of new therapies in rodent models of nicotine self-administration (SA). These models will be used to screen promising new compounds and to elucidate the neurobehavioral mechanisms underlying the effectiveness of the treatments, so that further improvements can be made. To follow-up the demonstration that pre-quit date nicotine therapy significantly increases successful smoking cessation, we will test selective ligands of nicotinic receptor subtypes beginning with a4B2 and a7 receptors for reducing nicotine SA. Our prior research has shown the importance of these receptors for the initiation and persistence of nicotine SA, respectively. Nicotine has cascading effects of stimulating the release of a variety of transmitters and these interacting systems are important for the variety of neurobehavioral substrates for nicotine reinforcement. One promising and relatively understudied transmitter system that interacts with nicotinic systems is the serotonergic system. Serotonergic 5HT2A+C antagonism has been shown in our previous studies to decrease nicotine SA in acute and chronic studies. We will determine which subtype, 5HT2A or 5HT2C is responsible for the effect so that we can avoid undue side effects of combined 5HT2A+C treatment. Neuroactive steroids such as pregnenolone sulfate and DHEA have shown promise for smoking cessation. We will determine the mechanistic bases for reducing nicotine SA via actions on GABA and glutamate receptors. These treatments will be assessed in models of IV nicotine SA driven by consummatory motor habit in comparison to the classic model of lever press response. These models of different drives for nicotine SA will be used to determine how different treatments affect the various motivating factors for nicotine SA. Anatomic localization studies with local brain region infusions will be used to determine the circuitry underlying the efficacy of the treatments found to be effective on a systemic level. The preclinical studies will further the Center's primary goal of developing more effective treatments to aid smoking cessation by: a) testing novel pharmacologic agents to reduce nicotine SA; b) determining neurobehavioral mechanisms for their effect; and c) mapping the neuroanatomic substrates for the effect to inform the optimal development of adaptive treatments that will help more people successfully quit smoking.

Project 2, Mechanisms of Neurobehavioral Dysfunction from Developmental Nicotine,& Tobacco, will determine how early life environmental tobacco smoke (ETS) exposure impacts neuronal differentiation, neural circuit formation and behavioral development resulting in persisting cognitive and emotional dysfunction. Neuronal and behavioral mechanisms will be studied in experiments tracing the progress from the incipient exposures to nicotine and tobacco during critical stages of cellular and organismal development, to the epigenetic and synaptic mechanisms that underiie behavioral dysfunction. Using a well characterized rat model for neurodevelopment, tobacco and nicotine will be administered by minipumps implanted subcutaneously to enable for continuous exposure that avoids the known stressors for rats that accompany direct smoke exposure. Cause and effect relationships between impacts on attention and memory as well as emotional function will be determined. We will compare the effects of tobacco and nicotine ranging from higher exposures modeling active maternal smoking to lower exposures characteristic of ETS. This project will provide the mechanistic link translating the epigenetic impacts of ETS to the cognitive impairments seen in children after developmental ETS exposure. Synaptic mechanisms underiying these behavioral effects will be determined with assessment of acetylcholine, dopamine, norepinephrine and serotonin systems known to be affected by nicotine exposures associated with active smoking during pregnancy. Cellular phenotypes of ETS and nicotine exposure will be determined in three validated in vitro models of neurodifferentiation, nerve growth factor-induced differentiation of rat PC12 ceils, differentiation of rat embryonic stem ceils to neurons and glia, and transdifferentiated human induced neurons. The investigation of epigenetic and neurochemical alterations from ETS will lead to studies of rescue and therapeutic treatments to avoid or reverse developmental ETS-induced cognitive and emotional dysfunction. This project will provide critical mechanistic translation between the molecular epigenetic studies of Project 3 and the clinical studies of ADHD in Project 1 to help children avoid lifelong impairment from developmental ETS exposure.

? DESCRIPTION (provided by applicant): The purpose of the International Neurotoxicity Association (INA) is to foster the science of determining the neural mechanisms and behavioral consequences of toxicants exposure. The bi- annual meeting (the 15th) is held for all in the field to communicate their latest research findings to their colleagues for continuing education and critical evaluation and to provide a forum for discussion of the current progress and directions for the future. INA would like to conduct a symposium with its annual meeting June 27-July 1, 2015 in Montreal, Quebec entitled Complementary Neurotoxicologically Insights from Fish, Flies, Bees, and Worms. This symposium will provide the latest information concerning the use of aquatic, insect, and nematode models as complementary models for neurobehavioral toxicology research. The speakers will include internationally renowned researchers. This symposium will provide integration of mechanistic research with animal models of neurobehavioral function. The speakers for the symposium will be Edward Levin, Duke University Medical Center, Stephanie Padilla from the US-Environmental Protection Agency and Martina Fenske from the Fraunhofer Institute and will speak about how zebrafish help with screening potential neurotoxicants; Philip Bushnell from the US-Environmental Protection Agency will speak about using drosophila for studying genetic contributions to solvent neurotoxicity; Dr. Nigel Raine from the University of Guelph in Ontario will speak about pesticide effects on memory in bees and Michael Aschner from Albert Einstein Medical Center will speak about C. elegans heavy metal neurotoxicology; Dr. Mamta Behl of the National Toxicology and National Institute of Environmental Health Sciences will give an additional talk about how non-mammalian animal models fit into neurotoxicology testing in the National Toxicology Program.. Recent breakthroughs and research challenges will be discussed so that an intelligent agenda for neurobehavioral toxicology research in the area can be devised. The audience will be scientists active in developmental neurobehavioral toxicology research. Bringing the intellectual resources and research methods of the scientists in this field to use zebrafish, insect and nematode models will greatly enhance our ability to characterize risks that may be posed by exposure to environmental toxicants. The forum will provide an opportunity for methodological and theoretical issues to be integrated in the context of each talk as well as in a discussion session. Funding is needed for travel of non-government speakers and accommodations. Importantly, for continuing progress the Principal Investigator asks for support of students and post-doctoral trainees to participate in the meeting. Special efforts will be made to increase diversity in the field through the trainee-sponsored travel to the meeting. A write-up of the symposium will be submitted to Neurotoxicology and Teratology, a leading peer-reviewed journal in the field.

ABSTRACT: Project 3. Preclinical Studies The preclinical project in the Center has the purpose of discovering new treatments which have promise for enhancing success with tobacco smoking cessation and to provide better basic understanding of the neurobehavioral processes underlying nicotine reinforcement to build a foundation for further treatment development. In the initial phase of the Center's research effort the preclinical project has provided promising new leads for medical treatments to aid smoking cessation and important neurobehavioral mechanistic information to help guide rational drug development for further progress in enhancing smoking cessation therapy. Two of our discoveries, the efficacy of the serotonin 5HT2c antagonist lorcaserin and the triple monoamine transmitter reuptake inhibitor amitifadine in significantly reducing nicotine self-administration (SA) will be advanced to human testing in the clinical project of the Center. Our project will continue this progress in the next phase of the Center's development. The rat model of nicotine SA will be used to build on our discovery of diverse treatments based on actions at nicotinic cholinergic, 5HT2c serotonergic, D1 dopaminergic, ?2 nordrenergic, H1 histaminergic and NMDA glutaminergic receptor systems will be followed up in three ways. 1) Combinations of these effective treatments will be evaluated to discover which would provide added therapeutic efficacy. 2) Differential efficacy of the diverse treatments will be tested in different subpopulations based on sex, adolescent or later age of onset of nicotine SA, low vs. high levels of nicotine SA, involvement of oral consummatory aspects of SA and pre or post cessation liability of nicotine SA. 3) The brain circuit mechanisms for the diverse treatments will be characterized through local brain area infusions of the different receptor-based treatments to see where the critical loci of actions are for the successful therapies. These studies will serve to refine the treatments for the tailored and adaptive treatment for smoking cessation in people. It has become clear that there is unlikely to be a single treatment that reaches all smokers to enable them to successfully quit. The diverse toolbox of treatments and further understanding of their mechanisms of action will help provide the clinical studies in our Center and the field in general to advance the goal of smoking cessation for the full variety of smokers.

The Neurobehavioral Toxicity Core (NBTC) will provide tests of neurobehavioral function for the animal model studies in the projects of the Duke Superfund Center. The spectrum of neurobehavioral assessment includes sensitive and on validated tests of sensorimotor performance, emotional response and cognition using zebrafish, killifish, rats and C. elegans. Assessment of spontaneous movement and motor responsiveness to sensory input at younger and older ages will be complemented by more complex tests of persisting neurobehavioral effects conducted in adolescence and adulthood including assessment of learning and memory, fear and anxiety and social behavior. The tests will be largely automated using computer driven operant and maze tasks in rats and computerized video tracking systems in the zebrafish, killifish and C. elegans. The NBTC will behaviorally assess the animals exposed by the individual projects and provide those projects with the statistical analyses of the outcome documenting short and long-term neurobehavioral impairments. The NBTC behavioral test batteries are tailored to provide sensitive an reliable to the neurotoxicity of early-life exposure effects on later-life function. The NBTC will continue to innovate to develop a broader spectrum of behavioral assessment tests as well as provide quicker through-put without sacrificing data quality. Functional behavioral effects can provide among the most sensitive indicators of developmental toxicity in animal models for risk assessment. Behavioral dysfunction is also among the most prevalent indicators of developmental toxicity in humans. The cognitive and emotional function tests can provide outcome measures very relevant to humans. The Neurobehavioral Toxicity Core will provide Projects 1, 2, 3 and 4 critical behavioral information about the functional meaning of the developmental toxicity they are investigating.

Cognitive dysfunction is one of the most prevalent persisting adverse effects reported in epidemiological studies of environmental toxicant exposure. Cognitive as well as emotional dysfunction have been found in children after developmental exposure to a wide variety of toxicants including pesticides, heavy metals and polycyclic and polyhalogenated hydrocarbons. Cognitive and emotional impairment are also seen in experimental animal models of developmental neurotoxic exposures, showing the cause-and-effect relationships between developmental toxicant exposure and persisting deficits in learning, memory, attention and anxiety. In our previous research in the Duke University Superfund Research Center (DUSRC) we have demonstrated the adverse effects of organophosphate (OP) pesticide exposures and persisting cognitive as well as emotional effects in rat models. These have been found to be related to OP induced disruptions of the transmitter systems acetylcholine (ACh) as well as the monoamines, dopamine (DA) and serotonin (5HT). These neurotransmitter systems have been shown in a wide variety of studies to play important roles in the neural bases of cognitive and emotional function. In the next phase of research with rats, we will determine how disruptions of ACh, DA and 5HT across different toxicant classes can impair cognitive and emotional function. We hypothesize that the persisting impacts of pesticides, flame retardants and polycyclic hydrocarbons on cognitive and emotional function involve an adverse outcome pathway converging on this neurotransmitter triad. Pharmacological challenges will determine causative relationships between ACh, DA and 5HT disruption and behavioral impairments. The neurochemical and pharmacological studies will inform our innovative development of therapeutic treatments of persistent cognitive and emotional deficits, directly helping people who have cognitive and emotional dysfunction due to early life neurotoxic exposure. We will complement the classic rat model with the innovative higher throughput zebrafish neurobehavioral model. We will determine conserved neurobehavioral pathways for the neurotoxic induction of cognitive and emotional impairment across toxicant classes. Showing that the ACh, DA and 5HT triad is conserved in the zebrafish model will establish a higher-throughput model to expand the number of chemical exposures that can be evaluated and related to mechanistic changes that underlie behavioral dysfunction. Understanding the neurotransmitter involvement in neurotoxicant induced cognitive and emotional dysfunction will not only provide a common basis for understanding the functional impairments caused by diverse toxicants, it also provides a basis for devising effective therapeutics for neurotoxic damage. This will bring generalized advances to the understanding of neurobehavioral toxicology based on underlying synaptic mechanisms rather than on the behavioral effects of individual chemicals. This multi-component biologically-based investigation progresses beyond classic adverse outcome pathways to an adverse outcome interacting systems approach.

The purpose of the International Neurotoxicity Association (INA) is to foster the science of determining the neural mechanisms and behavioral consequences of toxicants exposure. The INA bi-annual meeting (this is the 16th) is held for all in the field to communicate their latest research findings to their colleagues for continuing education and critical evaluation and to provide a forum for discussion of the current progress and directions for the future. Dr. Levin is the current president of INA. INA would like to conduct a symposium with its annual meeting May 20-24, 2017, in Florianopolis, Brazil, entitled ?Advancing Mechanistic Understanding of Neurotoxic Contributors to Autism.? This symposium will provide the latest information concerning the identification and mechanistic understanding of how environmental chemical exposure can increase risk of Autism Spectrum Disorders. Talks will span the range from experimental mouse and zebrafish models to epidemiological and clinical research. The speakers will include internationally renowned researchers. This symposium will provide integration of mechanistic research with animal models of neurobehavioral function. The speakers for the symposium will include Dr. Irva Hertz-Picciotto, University of California, Davis; Dr. Staci Bilbo, Harvard University School of Medicine; Dr. Marc Weisskopf, Harvard University School of Public Health; and Dr. Edward Levin, Duke University Medical Center. The conference will provide an opportunity for methodological and theoretical issues concerning environmental contributors to Autism to be integrated in the context of each talk as well as in a discussion session. Funding is needed for travel for non-government speakers and their accommodations. Importantly, for continuing progress we ask for support of students and post-doctoral trainees including trainees from under-represented minorities to participate in the meeting. Special efforts will be made to increase diversity in the field to under-represented minorities through the student travel award-sponsored travel to the meeting. A write-up of the proceedings of the meeting will be submitted to a leading peer reviewed journal in the field such as Neurotoxicity Research, NeuroToxicology or Neurotoxicoloty and Teratology.