Elise Weerts, Ph.D. - US grants

DESCRIPTION: (Applicant's Abstract) The purpose of the proposed research is to develop and refine a new animal model for the affective and/or motivational states that are elicited by drugs of abuse. Ultimately, the purpose is to identify behavioral measures that predict drug-taking behavior. Critical features of drug-taking and relapse are the positive (i.e., reinforcing) effects of drugs and the aversive state associated with cessation of chronic drug-taking and withdrawal. Nonhuman primates, including baboons, emit a variety of distinct vocalizations during aversive (e.g., social separation, predator alarm, and agonistic interactions) and positive (e.g., feeding, grooming and copulation) social contexts. Vocalizations during these averse or positive social situations appear to serve different social functions and may serve as indications of affective and/or motivational states such as "anxiety" or "contentment". The social and affective nature of vocalizations render them particularly attractive for research on the subjective training with an artificial apparatus. Moreover, vocalizations are altered by positive an aversive environmental stimuli, and are modified when psychoactive drugs are administered. The current research will focus on psychoactive compounds that are abused in humans and that previously have been shown to be self-administered. The current research will focus on psychoactive drugs are administered. The current research will focus on psychoactive compounds that are abused in humans and that previously have been shown to be self -administered in baboon. These will include drugs from various drug classes including psychomotor stimulants, opiods, and sedatives. In the first series of experiments, acute doses of drugs will be administered to baboons and their effects on the production and patterning of vocal and visual display behaviors will be recorded during observation sessions before, during and after drug administration. The relationship between visual displays (including social behaviors, agonistic behaviors, self-directed behaviors, motor activity and resting postures) and the type of species-specific vocalizations (i.e., "grunts" and "barks") will be characterized under different social context conditions. In addition, some drugs that are not self-administered by baboons will be tested in order to determine the specificity of drug effects on vocalizations. In the second series of experiments, selected drugs will be administered chronically to determine whether repeated drug exposure and/or physical dependence alters vocalizations over time. The development of an animal model for the affective and/or motivational states that are elicited by drugs of abuse will provide a basis for future research on the role of the subjective effects of drugs in the addictive process.

APPLICANT'S ABSTRACT: The goal of the proposed research is to develop a model of 'cue-reactivity' using a combination of classical conditioning and operant conditioning procedures. Environmental stimuli that have been repeatedly associated with drug and alcohol use elicit physiological and subjective drug-related effects in humans that abuse drugs and alcohol. Reactivity to drug-related stimuli (i.e., cues) is believed to be a function of classical conditioning processes and may play an important role in the development of compulsive alcohol drinking and in the propensity to relapse after periods of abstinence. A new animal model of cue reactivity has been under development in our laboratory in which a constellation of behaviors are reliably increased during presentation of a sequence of environmental stimuli (e.g., lights and tones) that precede the opportunity to consume alcohol, food or a preferred non-alcoholic beverage. These cue-related behaviors include time sensitive patterns of learned instrumental responses and general activity, as well as naturalistic behaviors. The proposed experiments will systematically examine the relationship between reactivity to alcohol-related cues, alcohol-seeking and self- administration. The first series of studies will evaluate whether cue-related behaviors are sensitive to the changes in the magnitude of the reinforcer (i.e., alcohol concentration) and amount of work effort required (i.e., number of lever responses) to obtain alcohol. These studies will also determine if there are differences in the type of behaviors that emerge with repeated drug-cue pairings and across a range of alcohol concentrations and response 'costs'. A second series of studies will evaluate the influence of length of abstinence on alcohol self- administration and reactivity to alcohol-related cues. A third series of studies will evaluate the interactions between environmental alcohol-related cues and the internal cues produced by alcohol itself on the reinstatement and maintenance of self-administration and cue-related behaviors. Acute 'priming' doses of alcohol or environmental cues will be presented under conditions in which alcohol is available for self-administration or withheld (i.e., abstinence). This research will determine whether cue-related behaviors reliably predict alcohol self-administration and reinstatement of drug-taking (i.e., relapse) during abstinence. This research will additionally provide important information on the behavioral processes underlying conditioned responses to drug-related cues in animals which may be relevant to cue-reactivity and drug-taking in humans.

DESCRIPTION: (provided by applicant) Gamma-hydroxybutyrate (GHB) is currently under investigation as a potential treatment for narcolepsy and alcohol dependence. Although GHB is currently classified as a Schedule I substance under the controlled substances act, illicit use of GHB, and its precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), is on the rise. The ability of GHB and its precursors to produce physical dependence has not been evaluated in controlled studies in humans or laboratory animals. The goal of the proposed research is to evaluate the physical dependence potential of GHB, GBL and 1,4-BD. Two specific aims are proposed: Aim 1 is to characterize the behavioral effects of GHB, GBL, 1,4-BD after acute and chronic intragastric drug administration in baboons. Aim 2 is to characterize physical dependence and the withdrawal syndrome for GHB and its precursors GBL and 1,4-BD in baboons. First, GHB, GBL and 1,4-BD will be administered alone and then in combination with the GHB antagonist NCS-382. Changes in food-maintained behavior, observed behaviors, and fine motor coordination, when compared to controls, will be evaluated. Next a high dose of GHB, GBL or 1,4-BD will be administered chronically via continuous i.g. infusion and changes in food-maintained behavior, observed behaviors, and fine motor coordination, when compared to vehicle control, will be evaluated. Then, the GHB antagonist NCS-382 will be administered to baboons that have been chronically treated with GHB, GBL or 1,4-BD. Evidence for a precipitated withdrawal syndrome will be determined based on changes in food-maintained behavior, observed behaviors, and fine motor coordination when compared those same behaviors recorded during the vehicle baseline and following administration of the antagonist alone. Finally, chronic treatment with GHB, GBL or 1,4-BD will be abruptly discontinued. The presence and time-course of a spontaneous withdrawal syndrome will be determined based on comparison with the same behavioral measures determined during a) the vehicle baseline condition and b) during the chronic drug dosing condition. The results of these studies will provide critical information on the behavioral pharmacology and physical dependence potential of GHB and its precursors.

DESCRIPTION (provided by applicant): The goal of the proposed research is to investigate the role of the major inhibitory neurotransrnitter gammaaminobutyric acid (GABA) in the reinforcing and discriminative stimulus effects of cocaine. Understanding the neurobiological mechanisms underlying the behavioral effects of cocaine are critical for the development of effective medications for cocaine addiction. The primary mechanism involved in the reinforcing effects of cocaine is activation of the mesolimbic dopamine (DA) system. Recent studies have indicated a modulatory role of GABA on mesolimbic DA activity, and drugs that facilitate GABAergic neurotransmission have been shown to alter some of the behavioral effects of cocaine in both humans and laboratory animals. The proposed studies will evaluate the effects of pharmacoiogical modulation of GABA on self-administration, reinstatement and discrimination of low and high doses of cocaine. GABAergic neurotransmission can be altered by a number of different mechanisms (i.e., activation or blockade of GABAA and GABAB receptors, inhibition of GABA transaminase, inhibition of GABA synthesis and inhibition of GABA reuptake); drugs affecting each of these mechanisms will be evaluated using several procedures to provide a comprehensive assessment of GABAergic influence on the behavioral effects of cocaine which may be relevant to addiction. Drug self-administration and reinstatement of drug-seeking in animals provide valid information on drug reinforcement and relapse, respectively. Drug discrimination procedures in animals provide information analogous to assessment of subjective effects in humans, and provide a highly selective behavioral measure which often corresponds with a drug's activity at a specific neurotransmitter system. One aim is to investigate if GABAergic drugs alter the rate and pattern of ongoing cocaine self-administration. A second aim is to explore if GABAergic drugs alter the motivation to take cocaine as measured by the maximum work output under a progressive ratio schedule of cocaine injection. The specificity of any effect on cocaine-taking will be evaluated in parallel studies with a non-drug reinforcer using the same procedures as for self-administration and progressive ratio. A third aim will determine if GABAergic drugs alter the 'priming' effects of cocaine on reinstatement of self-administration (i.e., drug-seeking). A fourth aim is to evaluate if GABAergic drugs alter the discriminative stimulus effects of cocaine. The results of these studies will increase our understanding of the role of GABA in the behavioral effects of cocaine and may lead to the development of better medications for the treatment of cocaine addiction.

[unreadable] DESCRIPTION (provided by applicant): Gamma-hydroxybutyrate (GHB) is a drug of abuse with potent CMS depressant effects. Chronic administration of GHB can produce physical dependence and the withdrawal syndrome reportedly resembles withdrawal from classic sedative-hypnotics (benzodiazepines and alcohol). The mechanisms underlying the pharmacological actions of GHB appear to involve multiple systems including GHB, Gamma-aminobutyric acid CGABA), and opioid. Three specific aims are proposed to further characterize the behavioral pharmacology and physical dependence potential of GHB. Aim 1 will evaluate the effects of dose and duration of GHB administration on development of physical dependence. A range of GHB doses will each be administered for the same duration and then a GABA-B antagonist will be administered. Signs of withdrawal and effects on food-maintained behavior will be characterized. Second, GHB dose will be held constant and the length of exposure will be varied. The severity of antagonist-precipitated withdrawal behaviors as a function of the length of GHB administration will be determined. Aim 2 will examine the behavioral effects GHB, benzodiazepine GABA-A and GABA-B receptor agonists and antagonists in non-dependent, GHB- dependent and GHB-withdrawn subjects. The ability of each drug to potentiate GHB effects, precipitate withdrawal and/or alleviate GHB withdrawal will be determined. These studies will determine if chronic GHB administration produces functional changes in GHB, GABA-A and/or GABA-B receptors as evidenced by shifts in the drug dose effect functions. Aim 3 will characterize the reinforcing effects and pattern of self- administration of GHB, and pro-drugs gamma-butyrolactone (GBL) and 1,4-butendiol (1,4-BD) using a 24-hr self-injection procedure. The relative reinforcing efficacy of each drug will be compared, as measured by the maximum work output or "breaking point" completed for each injection under a progressive ratio procedure. Physical dependence in the context of self-injection of GHB, GBL and 1,4-BD will also be evaluated. These studies will provide critical information on the behavioral pharmacology and dependence-producing effects of GHB. [unreadable] [unreadable] [unreadable]

Alcohol is one of the most widely used and misused drugs in the US. There is a critical need to continue to improve AUD treatment and develop new medications to reduce alcohol use and to include nicotine co-use in evaluations of candidate medications. This project proposes to investigate biobehavioral mechanisms underlying alcohol and nicotine use and co-use, and to test candidate medications in two animal models developed specifically for testing medications for alcohol abuse, and alcohol and nicotine co-use. The first model uses a Chained Schedule of Reinforcement (CSR) procedure in which seeking and consumption occur in the context of distinct environmental cues and behavioral contingencies to the influence of environmental stimuli on the drive to drink and the persistence of behaviors associated with chronic drinking. Two 2 matched groups of NHP with extensive histories of self-administration of alcohol (Alcohol group) or the non-alcoholic beverage (Control group) will be utilized. The second model is a new Alcohol and Nicotine Concurrent Access (ANCA) procedure in which oral alcohol and IV nicotine were concurrently available for self-administration. A functional assessment battery provides assessment of drug side effects. Aim 1 will determine whether test drugs reduce alcohol seeking and self-administration in the CSR under conditions of ongoing drinking and abstinence. Aim 2 will determine whether test drugs reduce alcohol and nicotine self-administration independently or concurrently under single drug access or ANCA procedures. Aim 3 will determine incidence of side effects of test drugs in the functional assessment battery. Drug candidates include bifunctional and universal opioid receptor (OR) ligands with different pharmacological profiles at OR subtypes, a universal OR/nociception opioid peptide (NOP) receptor ligand, the cannabinoid constituent cannabidiol (CBD), the neuropeptide oxytocin, and a nicotinic acetylcholine receptor partial agonist/antagonist varenicline. Naltrexone will be tested as a positive control and comparator. A drug with therapeutic potential would be one that reduces cue-maintained seeking, and decreases alcohol self-administration, and has a low side-effect profile. A drug with therapeutic potential in alcohol and nicotine co-users would decrease alcohol self-administration without increasing nicotine self-administration, and ideally would reduce self-administration of both drugs. Integration these data will provide new information on the behavioral and neuropharmacological mechanisms involved in alcohol abuse and alcohol/nicotine co-use. Comparison of dose effect functions and efficacy across models can inform treatment strategies for optimal dosing and timing of treatment. This information will ultimately facilitate medication development for the treatment of alcohol misuse and AUD.

Alcohol is one olthe most commonly abused drugs in the US, with 10% of the population affected by alcohol dependence at some point in their lives. Research over the last 20 years has demonstrated that individual dIfferences in subjective responses to alcohol may influence a person's pattern of alcohol use and is a strong predictor of future alcoholproblerns. Individuals with a low response to alcohol have an Increased-risk for alcoholism, where as Individuals With a-high response to alcohol have a reduced risk for alcoholism. Mu oploid receptors are involved in modulation of drinking behaviors and have been shown to be higher in recently abstinent alcoholics when compared to healthy controls. The current application furthur investigates the relationships between differences In brain mu opioid receptors and Individual differences In subjective responses to alcohol. We will recruit healthy social drinkers who Will complete an alcohol challenge procedure and be phenotyped based on their level of response to alcohol. Subjects who show a high response and a low response to aIcohol will undergo a [C11] carfentanil PET scan toobtain MOR BP to determine if individual differences in MOR BP are related to alcohol sensitivity under controlled laboratory conditions. The results of the proposed research will increase our understanding of to the relationship between individual variability in the opioid system and subjective sensitivity to alcohol.

DESCRIPTION (provided by applicant): The goal of this R21 proposal is to provide the foundation for future research to examine the utility of the neuropeptide oxytocin (OT) as a new treatment for alcohol use disorders (AUD). Interest in OT as an alcohol treatment stems from its role in adaptive processes including reward, associative learning, memory, and stress responses. Support for its use is based on studies in animal models of addiction showing that OT reduced alcohol reinforcement, attenuated drug tolerance, and decreased withdrawal symptoms. OT exerts its effects via interactions with the hypothalamic-pituitary-adrenal (HPA) axis, as well as dopamine mesolimbic reward and corticotrophin-releasing factor (CRF) stress systems. OT effects on stress systems are of high interest given the strong link between stress, alcohol drinking and relapse, and known dysregulation of HPA-axis activity in heavy drinkers. Both preclinical and clinical evidence provide evidence that OT may help to normalize blunted stress responses, and attenuate alcohol withdrawal associated hypercortisolism, negative mood and withdrawal symptoms. Using gold-standard laboratory procedures in heavy drinkers, we will examine the effects of intranasal OT administration on cortisol stress responses and different measures predictive of alcohol use and misuse under double-blind placebo controlled conditions. Aim 1 will examine the effects of oxytocin on alcohol withdrawal, including symptom severity, alcohol craving, cortisol and negative mood. Aim 2 will examine the effects of oxytocin on response to social stress. Aim 3 will examine the effects of oxytocin on motivation to drink. Aim 4 will examine the effects of oxytocin on alcohol sensitivity. These preliminary data will provide critical information on the potential of OT as a treatment for alcohol drinking problems and will provide the basis for determination of sample sizes for future comprehensive research and clinical trials.

Cannabis (marijuana, MJ) is the most widely used illicit drug. At the same time, there is growing medical use of MJ and other cannabinoids for treatment of pain and a range of disorders. As availability and use increase, there is concern regarding the consequences of MJ use, particularly for women who appear to be more sensitive to many effects of MJ. Unfortunately, women MJ users are an understudied population. Women show accelerated trajectories from first MJ use to the development of cannabis use disorder (CUD), experience more severe withdrawal, and worse treatment outcomes for CUD treatment, when compared to men. The rewarding and dependence producing effects of MJ are primarily due to ?-9-tetrahydrocannabinol (THC), the main psychoactive component of MJ, and its actions on cannabinoid type 1 receptors (CB1R). CB1R are widely distributed in the human brain and modulate multiple biological processes including regulation of mood, stress, pain, motor function, learning and memory. The proposed studies examine the role of brain CB1R on severity of MJ withdrawal, craving and negative mood during abstinence in women under experimentally rigorous conditions. Women, who are daily MJ users and meet DSM-5 criteria for moderate to severe CUD will be studied under an inpatient protocol that includes controlled smoked MJ administration, monitored MJ abstinence and 11C-OMAR PET imaging of CB1R during peak withdrawal. CB1R availability will be determined for key brain regions associated with drug reward (nucleus accumbens), mood regulation (amygdala and hippocampus), motor function and habit learning (caudate, putamen, globus pallidus) and cognition (frontal cortex). PET scans will also be completed in matched controls (no MJ use). Aim 1 will examine CB1R availability (VT ) in female MJ users and matched controls. We hypothesis that, when compared to controls, female MJ users will have lower VT , and the magnitude of downregulation will be correlated with severity of CUD. Aim 2 will evaluate whether severity of withdrawal during MJ abstinence is negatively associated with CB1R VT in female MJ users. We hypothesis that severity of withdrawal symptoms, negative mood and craving will be correlated with lower VT, particularly in the amygdala and hippocampus. Our exploratory aims will examine cognitive performance and subjective effects before and after smoked MJ administration in MJ users and explore the relationship of these measures to CB1 availability. The results of this study will provide needed preliminary data on whether CB1R may contribute to increased severity of MJ withdrawal in women, and will provide new information towards our understanding of cannabinoid mechanisms in MJ sensitivity and CUD in women. Given that the primary pharmacological treatments for CUD are those that act via the CB1R, and that women account for half of CUD treatment seekers, increasing our understanding of MJ effects on the brain and behavior in women is critical. The public health importance of this study includes identification of sex-specific symptoms, and the mechanisms that modulate them for improved treatment approaches.

Cannabis is the most widely used illicit drug in the world and its primary route of administration is via inhalation. As reported in the most recent National Survey on Drug Use and Health, 43 million people met criteria for cannabis use disorder (CUD) in the past 12 months. This finding is in light of the fact that cannabis is gaining acceptance for both medical and recreational use in the general population. Further, rates of daily cannabis use have increased and perceptions of harm associated with use have decreased. Consequently, treatment admissions for CUD are on the rise. Additionally, the use of e-cigarettes and other vaping devices for vaping of several drugs, including ?-9-tetrahydrocannabinol (THC), is becoming more common for medicinal and recreational use. The development of animal vapor models to evaluate THC vapor and other cannabinoid constituents would be invaluable to increasing our understanding of CUD, and the reinforcing effects of cannabinoid vapor as delivered via vaping devices. Inhalation devices for combusted marijuana and THC vapor are in use, and animal studies demonstrate pharmacological efficacy in the classic tetrad of behavioral paradigms used to detect cannabis effects (e.g., hypothermia, nociception, catalepsy, reduced motor activity). However, self-administration of vaporized THC or other cannabinoids in a rodent model has not been established. We propose to use a commercially available e-cigarette-based vapor system to evaluate the optimal parameters for THC vapor self-administration, and place conditioning. Aim 1 will utilize a passive THC vapor exposure procedure and a full range of THC concentrations to produce dose-dependent conditioned place preference and avoidance. In Aim 2, THC vapor will be available for self-administration under different schedules of reinforcement and access conditions. Aim 3 will examine THC self-administration under intermittent access conditions. Developing a THC vapor model of self-administration in rodents is critical for increasing our understanding of the behavioral and biological mechanisms of THC/cannabinoid vapor reward and CUD. This rodent model will allow for the evaluation of motivated behaviors driving THC/cannabinoid use, and allow testing of potential new pharmacotherapies for treatment of CUD.

SUMMARY Although most smokers want to stop smoking, few successfully quit long-term. ?7 nicotinic acetylcholine receptors (nAChR) are an important pharmacological target for development of new smoking cessation medications. ?7 nAChRs regulate cognitive processes of attention, learning and memory, as well emotional affect and reward, the same processes that are enhanced by acute nicotine, and disrupted during tobacco withdrawal. Preclinical research provides evidence that ?7 nAChR play a role in the reinforcing effects of nicotine and expression of nicotine withdrawal, and that these receptors are upregulated in key brain regions after chronic nicotine exposure. The proposed proof-of-concept pilot study will first quantify ?7 nAChR in recently abstinent tobacco smokers using human Positron Emission Tomography (PET) with an ?7 nAChR selective radiotracer (18F-ASEM) to determine if ?7 nAChR availability is higher in smokers when compared to healthy control nonsmokers, and if ?7 nAChR availability is correlated with magnitude of tobacco use (Aim1). Ain 2 will also explore the potential relationship of ?7 nAChR availability to clinically relevant measures of tobacco withdrawal during acute abstinence. Non-treatment seeking heavy smokers with TUD will be enrolled into an outpatient protocol that includes 18F-ASEM PET imaging of ?7 nAChR availability after 24-hrs of smoking abstinence. Self-report of tobacco craving, withdrawal discomfort, and negative affect as well as heart rate and performance on a task that measures attention processing will be assessed at baseline when smoking as usual, on the first day of abstinence, then each study visit during the quit attempt. We will use a standard, validated behavioral intervention (contingency management) to motivate smoking abstinence during the 8-day quit attempt; at each study visit participants will receive incentive payments contingent upon criterion levels of exhaled carbon oxide (CO) and urinary cotinine levels indicative of abstinence compliance, and number of days of successful abstinence will be determined. Use of 18F-ASEM is approved by the FDA for human use under an IND. These data provide a critical first step towards understanding ?7 nAChR characteristics in TUD and as a potential pharmacotherapeutic target to promote smoking cessation.

PROJECT SUMMARY Substance use disorders occur at the interface of behavior and pharmacology. This is a proposal to renew an ongoing and successful postdoctoral clinical research training program on the human behavioral pharmacology of substance abuse, for its 41st thru 45th years. Nine training positions are proposed, all at the postdoctoral level. Training duration is two to three years. The goal is to produce experts in various aspects of substance abuse, psychopharmacology, and treatment who go on to succeed as independent clinical researchers, scientists, academicians, and administrators in drug abuse and related fields. The program has a long and successful history, with many distinguished graduates. The program will provide training and experience in translational experimental clinical trials research methods, extending from the human laboratory to the clinic. Training consists primarily of conducting supervised clinical research in collaboration with training faculty and analyzing and publishing the results, conclusions and implications of that research. Trainees attend and report at major scientific meetings and participate in an organized program of educational seminars designed to provide both breadth and depth to their knowledge and skills relevant to drug abuse and clinical research. The training program site is a multifaceted drug abuse clinical research program -- the Behavioral Pharmacology Research Unit -- plus other affiliated drug abuse treatment and research programs, primarily on the same campus, but extending more broadly into the community as well. Research training is provided in the following areas: clinical pharmacology of drugs of abuse; medications development research; the cognitive neuroscience and behavioral toxicity of drugs of abuse; abuse liability assessment; pharmacological treatment of drug abuse; behavioral treatment of drug abuse, especially incentive-based strategies; integration of behavioral and pharmacological treatments; psychiatric and medical comorbidity; behavioral and neuropsychiatric assessment; HIV risk behavior assessment; promotion of engagement and adherence; and clinical trials research methods and trials management. Training includes a broad range of abused drug classes ? opioids, cocaine, prescription medications, cannabis, club drugs/psychedelics, alcohol, tobacco/nicotine, and caffeine.