Christopher L. Cunningham - US grants

Recent theories of the etiology of alcoholism suggest that craving and relapse are linked to a Pavlovian process whereby the drinker learns to associate environmental cues with alcohol's effects. If the individual returns to an environment where alcohol is expected but not given, he may experience an adverse conditioned physiological reaction similar to withdrawal which prompts renewed drinking. Pavlovian conditioned responses have also recently been shown to be involved in the growth of tolerance to some effects of alcohol. No study, however, has yet shown a direct link between conditioned drug responses and self-administration. Using an animal (rat) model for oral self-administration of alcohol, we propose several studies to examine the role of Pavlovian conditioning in self-administration. Initially, we will determine whether the environment associated with self-administration of alcohol becomes capable of eliciting a Pavlovian thermal conditioned response and, if so, whether that response contributes to the development of tolerance to alcohol's thermal effect. Then we will assess the effect of an explicit Pavlovian CS for alcohol (i.e., a stimulus previously paired with alcohol injection) on rate of responding in the self-administration paradigm. Finally, we will also determine the subject's preference/aversion for that stimulus using a locomotor choice procedure. The results of these studies will permit us to evaluate suggestions that Pavlovian conditioned responses play a critical role in the development, maintenance and relapse of alcohol self-administration and in the development of drug tolerance. The long-term objective of this research is to increase our understanding of the biobehavioral processes that contribute to the etiology of alcohol abuse and dependence. This understanding should help us to recognize increased risk of alcohol abuse, to devise more efficient and effective treatments for alcoholism and to outline more effective prevention strategies.

Recent theories of the etiology of drug addiction suggest that craving and relapse are linked to a Pavlovian process whereby the drug user learns to associate environmental cues with drug effects. If the individual returns to an environment where the drug is expected, but not administered, he may experience an adverse conditioned physiological reaction similar to withdrawal which prompts renewed drug taking. Pavlovian conditioned responses have also been shown to contribute to the growth of drug tolerance. No study, however, has yet shown a direct link between conditioned drug responses and self-administration. Using an animal (rat) model for intravenous self-administration of morphine, we propose several studies to examine the interplay between Pavlovian conditioning and operant self-administration. Using both dependent and nondependent rats, several studies will assess the role of critical conditioning parameters (interstimulus interval, drug dose, number of trials) on the classical conditioning of heart rate and body temperature by morphine and naloxone. We will also see whether the environment associated with drug self-administration becomes capable of eliciting conditioned physiological responses and whether such responses are correlated with the frequency of self-administration. Finally, we will manipulate the Pavlovian value of contextual cues by pairing them with morphine or naloxone; the behavioral impact of this conditioning on self-administration will then be assessed. The results of these studies will permit us to evaluate suggestions that Pavlovian conditioned responses play a critical role in the development, maintenance, elimination and relapse of drug addiction. The long term objective of this research is to increase our understanding of the biobehavioral processes that contribute to the etiology of drug abuse and dependence. This understanding should help us to recognize increased risk of drug abuse, to devise more efficient and effective treatments for drug addiction and to outline more effective prevention strategies.

DESCRIPTION: (Adapted from the Investigator's Abstract) This project is directly concerned with the learning and motivational processes underlying ethanol-seeking behavior. The long-term goal is to improve our understanding of the behavioral and neurobiological process that contribute to the etiology, maintenance, elimination and relapse of alcoholism. The general experimental strategy involves study of ethanol's motivational effects in oral self-administration and place conditioning tasks using animals. Special emphasis will be placed on the learning that results from the predictive relationship between environmental stimuli and exposure to ethanol rewarding or aversive effects. The central organizing hypothesis of this research is that ethanol-predictive stimuli have a direct impact on ethanol's motivational effects and that they are importantly involved in motivating or directing ethanol-seeking behavior, including the phenomenon of relapse after extinction or abstinence. One set of proposed experiments will examine effects of ethanol-predictive stimuli on conditioned hyperthermia and barpressing in a signaled self-administration procedure using rats and mice. Variables of interest include: Sucrose concentration, CS-ethanol overlap, ethanol access duration and conditioned reinforcement. The second set of studies will determine effects of ethanol-predictive stimuli on conditioned place preference and aversion in rats and mice. Variables of interest include: dose, number of trials, CS-ethanol interval, genotype, and route of administration. The final series of experiments will study the role of ethanol-predictive stimuli in extinction, relapse and relapse prevention. In addition to improving our understanding of ethanol-predictive stimuli, these studies will shed new light on apparent species differences in ethanol s motivational effects, and on findings that ethanol-predictive stimuli can acquire opposing motivational effects within the same species. A better understanding of these issues is essential for using these animal models to study neurobiological and genetic contributions to alcoholism. This project should help focus future research on the neurobiological mechanisms of ethanol-seeking behavior, aid in the development of beneficial treatments for alcohol abuse, and facilitate identification of effective relapse prevention strategies. These studies could prove to be especially useful in the evaluation of putative pharmacotherapies intended to reduce alcohol craving and in the design of behavioral interventions to decrease ethanol-seeking behavior.

This proposal requests funds to provide research apprenticeships during the summer to underrepresented minorities from Northwest area high schools. A parallel program will provide a research experience or internship for teachers who are either members of underrepresented minority groups or who teach or will potentially teach in schools having significant populations of underrepresented minorities. Both students and teachers will be matched with a mentor having ongoing research projects. The students will be true participants in the research projects and it is expected that they will report to their peers on their work and their mentor's research. During the summer both students and teachers will be exposed to scientific seminars, both in their mentor's field and in other research fields, the attempt being made to provide the broadest exposure to biomedical research. Three pre-existing programs will be combined in this single program. The school of Medicine and the school of Dentistry at Oregon Health Sciences University and the affiliated Oregon Regional Primate Research Center (ORPRC) have a long history of administering summer programs. We believe that by combining the programs we will be able to provide better exposure to the broader fields of biomedical research.

No Abstract Provided

A broad goal of this Center is to combine the use of Quantitative Trait Loci (QTL) linkage mapping techniques with several different animal genetic models to identify and localize genes affecting behavioral and pharmacological responses to ethanol. Our previous studies have revealed substantial genetic variability within the BXD recombinant inbred strains in three different ethanol phenotypes believed to be relevant to understanding the rewarding and aversive effects of ethanol: ethanol drinking, conditioned place preference, and conditioned taste aversion. Moreover, our studies suggest partial overlap in the genetic mechanisms influencing these behaviors and QTL analyses have identified several chromosomal regions of potential interest. However, because of limitations imposed by the statistical strategy used for QTL mapping, these loci must be considered provisional until they are confirmed by additional studies. Thus, the goal of this Component Project is to verify several of the strongest QTL identified for each of these ethanol reward phenotypes (e.g., withdrawal, hypothermia, ataxia). Our primary strategy for QTL verification involves testing of F2 mice derived from the BXD progenitor strains, C57BL/6 (B6 and DBA/2 (D2), and genotyping high responders and low responders at markers flanking the provisional QTL. The importance of QTL verified in this population will be evaluated further in studies in which F2 mice are selectively bred on the basis of their genotype at markers flanking a verified QTL (Genotypic Selection). These mice will then be tested for differences in the behavioral phenotypes to determine the role of allelic status at the QTL of interest. Genotypic selection will also sere as the starting point for the development of Congenic Strains in which either the B6 or D2 allele at a target QTL is transferred to the background of the opposite progenitor strain by repeated backcrossing. These oncogenic strains will facilitate future research aimed at identifying specific genes influencing each behavioral phenotype. Finally, to evaluate the genetic interrelatedness of these behavioral phenotypes, we will examine correlated responses to selection in mouse lines that have been selectively bred for differences in sensitivity to ethanol' behavioral effects in each of these tasks (Phenotypic Selection). These selected liens will also be genotyped at appropriate markers to determine whether divergence in the behavioral phenotype is accompanied by divergence in gene frequency. Once candidate genes have been identified in the mouse, homologous genes or regions of the human chromosome can be studied in detail to determine whether they are linked to alcoholism.

This competing continuation application requests funds to provide summer research apprenticeships for 16 disadvantaged students from Northwest area high schools. A parallel program provides a research experience or internship for two teachers who teach in schools have significant populations of disadvantaged students. Students and teachers are matched with faculty scientist preceptors who have ongoing research programs in the Schools of Medicine or Dentistry at the Oregon Health Sciences University or at the affiliated Oregon Regional Primate Research Center or Portland Veterans Affairs Medical Center. Students and teachers are true participants in these research projects and they are expected to report to their peers on their work and their mentor's work. In addition to participating in daily activities in their preceptors' laboratories, all trainees meet weekly during the summer for a series of seminars that address a wide range of scientific and ethical issues in various areas of biomedical research. The long-term goals of this program are to give disadvantaged students and teachers hands-on exposure to health-related research and to create more pathways for disadvantaged students to establish careers in the health sciences.

This INIA Consortium U01 Project is focused on genetic differences and neuroadaptations in brain circuitry that are responsible for individual differences in vulnerability to excessive consumption of alcohol. We will extend our previous findings using an intragastric consumption (IGC) model in which several days of passive exposure to ethanol (or water) via a chronic intragastric (IG) cannula are followed by a self-infusion test procedure in which voluntary ingestion of a flavored solution is paired with IG ethanol. Previously, we found that IGC and preference for the ethanol-paired flavor (compared to a water-paired flavor) is enhanced by passive ethanol exposure and varies as a function of genotype in both rats and mice. We now propose to focus primarily on mice. Aim 1 will examine key parameters of the passive infusion phase in two inbred strains, C57BL/6J and DBA/2J. These parameters include: (a) dose per infusion and total daily dose, (b) number of daily ethanol infusions, and (c) number of days of passive ethanol exposure. Aim 2 will further address the hypothesis of genetic differences in sensitivity to dependence-driven ethanol reinforcement by extending the model to characterize IGC in 15 standard inbred strains, allowing examination of genetic correlations between IGC and a wide range of previously studied ethanol phenotypes. With support from the INIA Colorado Gene Array Core, we will also examine genetic correlations with whole brain gene expression. Aim 3 will test whether passive IG ethanol exposure produces changes in ethanol reinforcement/reward using the conditioned place preference procedure and limited access operant self-administration. Aim 4 will involve collaboration with other INIA projects by testing two mouse models that have been selectively bred for high blood ethanol concentrations in binge drinking procedures: (a) the SHAG and SLAC lines, and (b) the HDID line and its genetic control (HS/Npt). Finally, with support from the INIA Neurocircuitry Mapping and Genotyping Core, Aim 5 will use c-Fos immunohistochemistry and lesions to identify specific brain areas that influence the enhancement in IGC after passive ethanol exposure. The long-term goal of this project is to understand the genetic and neurobiological processes underlying the excessive drinking that contributes to alcoholism in humans. By improving our understanding of these processes, we can identify more effective treatment and prevention strategies.

DESCRIPTION (provided by applicant): This project examines the effects of genetic background and past experience with alcohol on voluntary alcohol intake using an innovative animal (mouse) model of Intragastric Alcohol Consumption (IGAC). Recent research with this model has shown that intermittent passive exposure to alcohol (but not water) produces a large increase in subsequent alcohol intake in several mouse genotypes, including genotypes that normally avoid alcohol in drinking procedures. Our aims are designed to test the general hypothesis that individual differences in vulnerability to excessive alcohol intake are jointly determined by environmental and genetic influences on alcohol-induced neuroadaptations that contribute importantly to the development of alcoholism in humans (i.e., tolerance, dependence, withdrawal and learning). Aim 1 will assess possible pharmacological and behavioral mechanisms of enhanced voluntary intake after passive ethanol exposure in two well-studied inbred mouse strains, the C57BL/6J (B6) and DBA/2J (D2). Studies will examine the specificity and persistence of dependence-enhanced alcohol intake, stress levels, dispositional tolerance, the decay of functional tolerance (to both alcohol hypothermia and alcohol-induced conditioned taste aversion) as well as alcohol's ability to condition preference to a paired flavor when mice self-infuse alcohol during the acute phase of withdrawal. Aim 2 will provide new information on genetic mechanisms involved in dependence-enhanced alcohol intake in mouse lines selectively bred for differences in alcohol drinking preference (HAP3/LAP3) or alcohol withdrawal severity (WSP/WSR) by testing the hypothesis that common genes influence alcohol drinking, IGAC and withdrawal severity. Aim 3 will identify brain systems that mediate dependence-enhanced alcohol intake in alcohol-dependent D2 mice by disrupting three candidate brain areas thought to play important roles in dependence-induced increases in voluntary alcohol intake (amygdala, caudolateral substantia nigra, nucleus accumbens). Initial studies will use temporary inactivation of these candidate areas during acute withdrawal to identify target areas for follow-up studies that will assess the roles played by specific neuropharmacological systems using receptor-specific drug pretreatments during acute withdrawal. Aim 3 will also provide new information on the time course of negative reinforcement produced by withdrawal relief during the first day of acute withdrawal. The long-term goal of this project is to understand the environmental, genetic and neurobiological processes underlying the excessive drinking that contributes to alcoholism in humans. By improving our understanding of these processes, we can identify more effective treatment and prevention strategies. PUBLIC HEALTH RELEVANCE: Our long-term goal is to understand the environmental, genetic and brain mechanisms that underlie excessive alcohol intake in human alcoholics. This project uses an innovative animal model to study basic processes related to alcohol reinforcement (positive and negative), tolerance, dependence and withdrawal, all of which are thought to affect the development of alcoholism as well as relapse after abstinence. Information obtained from this research could be especially useful in the future identification of pharmacological and other interventions to reduce alcoholic drinking behavior.