Kathleen Kantak - US grants

cocaine; dopamine receptor; nutrition related tag; metal metabolism disorder; magnesium; nutrient drug interaction; euphoria; drug abuse chemotherapy; behavioral medicine; bromocriptine; desipramine; brain metabolism; magnesium deficiency; dextroamphetamine; self stimulation; lithium; methylphenidate; clinical chemistry; laboratory rat; laboratory mouse;

The proposed preclinical studies would address several issues that concern the vaccination program in human cocaine addicts in an effort to both evaluate the proposed clinical designs and to provide direction for future strategies. In accordance with these goals, the Specific Aims of Project 2 are as follows: 1. To determine if anti-cocaine antibodies block both the discriminative stimulus and reinforcing stimulus effects of cocaine and if the outcome of each procedure in rats can predict the clinical efficacy of the vaccine. 2. To determine the behavioral specificity of the decreases in self-administration responding engendered by anti-cocaine antibodies and other co-medications by examining their effects on responding maintained by a non-drug reinforcer. 3. To determine if cocaine use during the immunization period will alter the efficacy of the vaccine. 4. To determine the synergistic effects of the vaccine with other co-medications for reducing cocaine self-administration during and after the immunization period. By way of background and significance, the proposal indicates that an important component of medications development for cocaine addiction treatment is the development of cocaine antagonists. Along these lines, the feasibility of an antibody approach for blocking the effects of cocaine has been demonstrated to some extent. Further, passive administration experiments conducted in the PI?s laboratory suggested that a blockade of the reinforcing effects of self-administered cocaine may be conferred by anti-cocaine antibodies. Since addiction to cocaine is thought to be related to both its reinforcing and discriminative stimulus effects, the proposal presents plans to use intravenous self-administration and drug discrimination procedures to extend these initial findings. Since drug self-administration behavior in animals positively correlates with abuse of that drug by human subjects and drug effects in drug discrimination tests in animals positively correlate with subjective effects in human subjects, it is hypothesized that anti-cocaine antibodies should block both of these properties without producing any non-specific behavioral effects to be maximally effective in treating people addicted to cocaine.

DESCRIPTION (provided by applicant): During the previous funding period, individual memory systems were evaluated for their role in regulating associative learning processes studied in an eight-arm radial maze as well as in regulating behavior studied in a self-administration maintenance/reinstatement model in rats. The results generated specific hypotheses to suggest (1) that the rostral and caudal subregions of basolateral amygdala are functionally heterogeneous and may therefore have a differential sensitivity to dopamine agonists and antagonists for modifying drug-seeking under maintenance and reinstatement conditions; (2) that the lateral dorsal striatum may regulate the dose-related effects of self-administered cocaine; (3) that the hippocampal subicular subregions may regulate drug-seeking behavior during the contextual encoding (acquisition) stage, but not after contextual information is consolidated; and (4) that within session changes in DA neurotransmission in the lateral prefrontal cortex may regulate the within session changes in the pattern of drug-seeking behavior normally observed. Specific aim 1 will test these four hypotheses. For specific aim 2, the interactions between memory systems that are interconnected within two parallel corticostriatalpallidothalamic circuits as well as within the corticostriatalpallido-subthalamic circuit (interface between the basal ganglia and limbic system) will be explored. Specific hypotheses to be tested will be guided by conducting simulations with our newly developed neurocomputational model of drug-seeking behavior. In in vivo experiments, Fos protein expression in the nucleus accumbens at different phases of the cocaine addiction process will be measured in conjunction with the asymmetric GABA agonist inactivation technique to help elucidate if components of these different circuits work cooperatively, competitively or independently in regulating addiction-related behavior. The completion of these aims will advance our understanding of how neurocognitive substrates may regulate drug use and relapse. By studying memory system functions and their interactions during different phases of the cocaine addiction process, insight into the complex challenges that face successful treatment of cocaine-addicted individuals will surface and perhaps guide medications development.

The Trans-NIH Mouse Initiative is now underway for developing new, cost-effective, high throughput phenotyping techniques to assess specific components of central nervous system function in inbred strains of laboratory mice. One purpose for developing such techniques is to apply this technology to mutant mice; with the expectation that the genetic analysis of complex traits will be facilitated and that basic brain processes and diseases of the central nervous system will be better understood and treated. Numerous mouse knockouts now exist, but little is known regarding the functional significance of their altered genetics. There are many complex behaviors of interest in the Trans-NIH Mouse Initiative; among them are cognition, learning and memory, and the taking and seeking of drugs of abuse. The goal of this research is to develop a new method of cocaine self-administration that can be used long-term in inbred and genetic knockout strains of mice to simulate the full array of human behaviors or experiences associated with drug addiction. These include the acquisition, maintenance, extinction and reinstatement of drug-seeking and drug-taking behavior. The present proposal seeks to develop a method of cocaine self-administration whereby a discrete dose of aerosolized cocaine is intermittently delivered to a sniff port after a nose-poke response, thus avoiding many of the limitations imposed by previous methods. There are three specific aims to accomplish this goal: (1) Design an apparatus that can reliably deliver a discrete dose of aerosolized cocaine on an intermittent basis; (2) Develop and validate this inhalation method of cocaine self-administration in an inbred mouse strain by training mice to nose pole for cocaine delivery and by varying both the dose of inhaled cocaine and the response requirements necessary for obtaining it; (3) Apply this method in inbred and genetic knockout strains of mice by studying the effects of nitric oxide synthase deficiency on the acquisition, maintenance , extinction and reinstatement of cocaine-seeking and cocaine self-administration in neuronal NOS knockout mice and in inbred strains of mice after NOS inhibitor treatment.

DESCRIPTION (provided by applicant): An emerging clinical approach to treat substance abuse disorders involves a form of cognitive-behavioral therapy whereby addicts learn to reduce their reactivity to drug-paired stimuli through cue-exposure or extinction training. It is, however, unlikely that extinction training would be consistently effective as a stand- alone treatment in populations that have abused drugs long-term because the key memory systems that are recruited during extinction training are impaired by long-term drug use. There is a critical need to understand mechanisms underlying extinction learning and to establish viable strategies to increase the efficacy of extinction therapies for substance abuse disorders. Key elements of the proposed research plan build on recent advances made in the treatment of conditioned fear and anxiety and other cognitive disorders by pharmacological modulation of glycine, an obligatory co-transmitter at the NMDA glutamate receptor complex. The specific aims of the proposed research in rats and non-human primates are to: 1) elucidate the neurobiological substrates of extinction learning;2) evaluate selected glycine site partial agonists and glycine transporter-1 (GlyT1) inhibitors as candidate pharmacotherapies to increase the efficacy of extinction training;and 3) determine neurobiological substrates of glycine site modulation of extinction learning. The intravenous cocaine self-administration procedure will be used in the proposed studies because the contingency between drug delivery and behavior is likely paramount for understanding the persistent abuse of drugs in people. Measurement of Fos protein expression (a marker for neuronal activation) and evaluation with anisomycin (an inhibitor of de novo protein synthesis) will be used in rats to investigate the neurobiological substrates of extinction learning following cocaine self-administration training. In addition, the proposed research in rats and non-human primates will specifically investigate the effects of the partial glycine agonist D-cycloserine and selective GlyT1 inhibitors for their ability to accelerate extinction learning and to subsequently reduce cocaine cue reactivity and re-acquisition of cocaine self-administration. Animal research involving pharmacological modulation of learning and memory is well-served by an integrated comparative strategy using appropriately selected laboratory animals. This approach is especially relevant for research involving cognitive enhancing drugs, where non-human primates can serve as a key translational interface for the development of pharmacotherapies.

PROJECT SUMMARY/ABSTRACT The goal of this project is to investigate strategies that augment the acquisition and retrieval of extinction memory as a means to compete with and subsequently inhibit the reemergence of drug memory during periods of cocaine reexposure. We previously developed a novel animal model of cue exposure therapy for cocaine addiction treatment that incorporates drug memory retrieval methods with extinction training as a means to inhibit cocaine relapse. We found that adding a glycine transporter-1 (GlyT-1) inhibitor significantly enhanced the effectiveness with which cocaine-cue extinction training subsequently reduces reacquisition of cocaine self- administration in adult male rats and monkeys. In this project, we propose to extend our treatment model to include environmental enrichment (EE), a documented behavioral procedure that improves learning and memory in rat and man. Our work will focus on the introduction of limited (4hr) periods of EE scheduled in conjunction with weekly sessions of cocaine-cue extinction training, an approach that augmented the rate of extinction learning and reduced reacquisition of cocaine self-administration in preliminary studies. To implement a multi-modal approach for which sex as a biological variable will be monitored, we will examine the combined effects of EE and GlyT-1 inhibition with cocaine-cue extinction training in adult male and female rats (Aim 1). Synergy between these combined treatments for augmenting acquisition and retrieval of extinction memory to reduce cocaine relapse is hypothesized. To broaden the scope of our investigation, we will examine molecular changes in key brain regions that underlie the effects of EE and a GlyT-1 inhibitor. We will focus on receptors for glutamate (NMDAR; AMPAR) and brain derived neurotrophic factor (TrkB) as well as on two novel targets Nedd4 and USP46, as these influence the primary cellular means by which learning, memory and synaptic plasticity unfold. Our preliminary studies support an investigation of these targets, particularly in basolateral amygdala and ventromedial prefrontal cortex. We plan a dual approach in which expression, trafficking and ubiquination of relevant protein targets (Aim 2) as well as viral-mediated knockdown and overexpression of those targets (Aim 3) will be studied in male and female rats treated with EE and a GlyT-1 inhibitor combined with extinction training. An investigation into how these two strategies (EE and GlyT-1 inhibition) synergize in combination in rats could have considerable scientific and clinical significance. Results from these studies will help identify mechanisms that mediate behavioral improvements attained through our multi-modal treatment intervention. Identifying critical changes in these targets as a result of extinction training combined with EE and GlyT-1 inhibition may aid in the development of pharmacotherapies with novel mechanisms of action and in the discovery of unique behavioral therapies that enable therapeutically relevant synaptic plasticity that inhibits relapse to cocaine abuse in adult men and women.

PROJECT SUMMARY/ABSTRACT Opioid overdose, occurring as part of opioid mono-substance use (MSU) and, more intensely, among those with poly-substance use (PSU), has reached an epidemic level in the United States, and is reflective of other high-risk behaviors among those with PSU. Accordingly, there is an urgent public health need for improved treatment and prevention strategies for these populations, as guided by findings on the etiology and nature of both laboratory-assessed and clinical harm-avoidance deficits. Our purpose is to evaluate the nature and significance of laboratory-assessed harm avoidance deficits in order to identify potential treatment targets (mechanistic outcomes) that may underlie devastating, clinical harm-avoidance deficits, characterized by high risk for blood-borne viruses, criminality, and repeated overdoses among those with opioid PSU relative to MSU. In the animal model, we examine whether laboratory-assessed harm avoidance deficits (assessed via drug self-administration punishment and subsequent operant avoidance paradigms) arise from pre-existing inhibitory control deficits, drug use, or the combination of these factors, specifically evaluating differences in harm-avoidance capacity in mono (heroin or cocaine) vs. poly (heroin + cocaine) substance use models. Our subsequent work in humans will use two fear-based (acquisition of learned fear association, operant avoidance of this association) and two monetary-based (Iowa Gambling Task and monetary choice) laboratory measures of harm avoidance deficits to compare the severity of laboratory harm avoidance deficits in outpatients with opioid MSU or opioid+stimulant PSU. We will use these measures to predict and understand the nature of clinical harm-avoidance deficits in this sample of men and women. Close analogue procedures have been built into the animal and human studies, with the human studies providing a quasi-experimental or associative replication of the animal paradigms, i.e., allowing the tightly controlled experimental evidence (allowing causal conclusions) from the animal phase to aid the design and interpretation of less controlled, predictive models in the human stage.