Howard Gutstein - US grants

Pain is one of the most common, yet difficult to manage, clinical problems that physicians face. It is well known that pain is a stressful experience. However, pain clearly is perceived differently from non- nociceptive stressors. This proposal approaches the interface between stress and nociception in rodents with the following goals: 1) to explore the neuronal substrates that may give nociceptive stimuli their uniquely aversive qualities, 2) to determine how stress modulates neuronal responses to noxious stimulation, and 3) to correlate changes in pain behavior caused by narcotics with changes in neuronal activation at the supraspinal level, in order to identify specific brain areas that may be responsible for narcotic.induced alterations in response to nociception. We propose to accomplish these goals by correlating behavioral changes observed after different types of nociceptive and stressful stimulation with patterns of immediate early gene (IEG) expression induced by these stimuli. These patterns will be mapped using in situ hybridization. Both noxious and stressful stimuli have been shown to induce changes in IEG expression in relevant neuronal systems. However, most work in nociceptive IEG activation has focused on the spinal cord. Few studies have examined the supraspinal components of this response, and this work has typically been done in anesthetized animals. We propose a series of logically progressing studies designed to answer the following questions: 1) Do nociceptive and non-nociceptive stressors activate distinct neuronal systems? 2) What changes in IEG activation patterns occur during chronic nociceptive states, and how docs chronic exposure to nociceptors affect responses to acute nociceptive stimuli? 3) Does the stress history of an animal alter neuronal responses to acute nociceptive stimuli? 4) What are the effects of narcotics on pain behavior and supraspinal IEG activation when administered before or after nociceptive stimulation? We hope this information will improve the understanding of the basic mechanisms underlying aversive and affective responses to pain, and possibly lead to therapies that could help alleviate the suffering associated with pain in man.

DESCRIPTION (Applicant's Abstract): This is an application for a Small Grant Award under the priority category of newer, less experienced investigators. Opioids are the most important drugs used in pain treatment. However, in addition to desirable analgesic properties, opioids have undesirable side effects such as the development of tolerance, physical dependence and the risk of addicition. We propose that tolerance development involves a series of layered events that result in a complex clinical picture. Very little is known about the signaling mechanisms underlying the development of acute tolerance and cross tolerance to opioids or the temporal sequence of these adaptations. The long term goals of this research are to understand signaling mechanisms responsible for the development of tolerance to, cross tolerance to, and physical dependence on opioids. The short term goals of this proposal are to characterize the role of extracellular signal related kinase (ERK) in the development of acute tolerance and cross tolerance, and to determine the relevance of these findings in behaving animals. We shall achieve these goals by using molecular and behavioral techniques to test the following hypotheses: A) Opioid tolerance may be mediated by the extracellular signal regulated kinase (ERK) cascade. B) Desensitization of ERK responses may be responsible for the development of cross-tolerance. To test these hypotheses, we propose studies with the following specific aims: Aim 1: To correlate ERK activation by mu opioid agonists to their receptor binding affinity, efficacy, or in vitro potency. Aim 2: To characterize trhe effects of acut mu opioid administration on ERK activation by subsequent doses of agonists or potential cross-tolerating agents. Aim 3: To assess the effects of ERK cascade inhibitors on the development of acute opioid tolerance in behaving animals. Taken together, these studies will correlate ERK activation with other indices of agonist efficacy and potency, and assess the role of ERK in the development of acute opioid tolerance. These experiments could lead to the identification of novel therapeutic targets that may eventually enable physicians to sustain the effectiveness of opioid analgesics while diminishing their undesirable side effects and addictive potential.

DESCRIPTION (provided by applicant): A critical issue for the neurobiology of drug addiction is what changes are responsible for the transition from non-dependent drug use to addiction. The goal of the present proposal from a new investigator is to begin to explore the neurobiological mechanisms responsible for drug escalation and define the molecular mechanisms responsible for mediating the change from drug use to addiction. To achieve this goal, we will test the following hypotheses: 1) Sufficient exposure to heroin and cocaine leads to changes in specific elements of the extended amygdala to produce elevations in hedonic set point that in turn leads to progressive elevation in drug intake. A subhypothesis is that the neurobiological basis of this transition to drug escalation reflects the development of drug addiction; 2) These neurobiological changes involve cellular effects at the translational and post translational levels that alter protein expression levels and function; 3) The transition to addiction does not occur as a result of one discrete neurochemical change; rather, a series of layered changes developing over the course of the drug escalation process; and 4) These changes represent the "switches" responsible for the transition from drug use to addiction, and are similar even for different classes of abused drugs. To test these hypotheses, we propose studies with the following Specific Aims: 1) To compare and contrast changes in protein expression and modification associated with excessive levels of heroin intake with those associated with escalated cocaine intake; 2) To define the time course of changes in protein expression and modification during the development of heroin and cocaine escalation; and 3) To define persistent changes in protein expression and modification associated with abstinence and with relapse upon re-exposure to heroin or cocaine. Our proposed combination of cutting-edge behavioral, neuroanatomical, and proteomic approaches will permit the identification of important molecular substrates of the transition from casual drug use to addiction. It is hoped that these findings will eventually lead to improved treatments for these devastating conditions.

DESCRIPTION (provided by applicant): Critical issues for improving the treatment of alcoholism are what neurobiological changes are responsible for the transition from non-dependent alcohol use to alcoholism, and what persistent changes mediate relapse. The goals of the present proposal are to begin to explore the neurobiological mechanisms responsible for alcohol escalation and to begin to define the mechanisms responsible for relapse. To achieve these goals, we will test the following hypotheses: 1) Sufficient exposure to alcohol leads to changes in specific elements of the extended amygdala that produce elevations in the hedonic set point. In turn, this leads to progressive elevation in ethanol intake and a propensity to relapse during abstinence. 2) Self-administration of ethanol coupled with passive administration causes changes in protein expression levels and function more characteristic of the addictive process than passive administration alone. To test these hypotheses, we propose studies with the following Specific Aims: 1) To examine the effects of ethanol dependence on protein expression and modification with a focus on changes associated with ethanol reinforcement. 2) To determine long-lasting changes in protein expression and modification associated with vulnerability to relapse upon re-exposure to ethanol. Our proposed combination of cutting-edge behavioral, neuroanatomical, and proteomic approaches will permit the identification of important molecular targets that should enable the development of more specific and effective pharmacotherapy both to help block the process of alcohol addiction and prevent relapse in those suffering from alcoholism.

[unreadable] DESCRIPTION (provided by applicant): Critical issues for improving the treatment of alcoholism are what neurobiological changes are responsible for the transition from non-dependent alcohol use to alcoholism, and what persistent changes mediate relapse. The goals of the present proposal are to delineate brain biomarkers that indicate the neurobiological mechanisms responsible for alcohol escalation and to define brain biomarkers associated with relapse. To achieve these goals, we will test the following hypotheses: 1) Sufficient exposure to alcohol leads to changes in specific elements of the extended amygdala that produce elevations in the hedonic set point. In turn, this leads to progressive elevation in ethanol intake and a propensity to relapse during abstinence. 2) Self-administration of ethanol coupled with passive administration causes changes in protein expression levels and function more characteristic of the addictive process than passive administration alone. To test these hypotheses, we propose studies with the following Specific Aims: 1) To examine the effects of ethanol dependence on protein expression and modification with a focus on changes associated with ethanol reinforcement. 2) To determine long-lasting changes in protein expression and modification associated with vulnerability to relapse upon re-exposure to ethanol. Our proposed combination of cutting-edge behavioral, neuroanatomical, and proteomic approaches will permit the identification of important biomarkers that should enable the development of more specific and effective pharmacotherapy both to help block the process of alcohol addiction and prevent relapse in those suffering from alcoholism. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): It is estimated that over 100 million Americans suffer from chronic pain at an annual cost to our society of over 500 billion dollars. For centuries, opioid drugs such as morphine have been the first-line treatment for severe pain. However, over time tolerance to opioid analgesia develops. Patients face increased risk as well as suffering when opioids lose effectiveness. In this proposal I describe our groundbreaking discovery that the clinically used epidermal growth factor receptor (EGFR; ErbB1) antagonist gefitinib (Iressa) completely reverses morphine tolerance. Based on our findings, we hypothesize that: 1) ErbB signaling is necessary and sufficient to cause morphine tolerance; 2) Chronic opioid administration increases ErbB signaling and may underlie the phenomenon of incomplete cross tolerance; 3) Chronic opioid administration differentially regulates ErbB expression and co-localization in the dorsal root ganglion and substantia gelatinosa; and 4) Opioid-induced ErbB signaling outputs are determined by a tightly regulated transcriptional network. We will test these hypotheses by performing studies with the following Specific Aims: 1) Define the mechanisms by which ErbB receptor signaling mediates opioid tolerance; 2) Determine the effects of opioid tolerance on ErbB signaling and whether ErbB signaling can explain incomplete cross tolerance; 3) Define the specific cellular subtypes expressing ErbB receptors in the dorsal root ganglion and dorsal horn of the spinal cord, and determine if their anatomic relationships are altered by chronic opioid administration; and 4) Determine the regulation of ErbB signaling responses induced by opioids, and begin to define the network structure that underlies these responses. These studies should dramatically improve our understanding of the molecular mechanisms underlying opioid tolerance. They also may lead to a completely new approach for the treatment of chronic pain. Our findings have the potential to dramatically reduce human suffering and improve the quality of life for untold millions of patients suffering from intractabl pain.

DESCRIPTION (provided by applicant): The overarching goal of this proposed training program is to integrate interdisciplinary and translational aspects of the current, rich training environment in pain research at the University of Pittsburgh. In addition to exposure of trainees to fundamental principles of pain mechanisms and pain presentation, we will establish new program elements (clinical experiences, multi-laboratory projects, courses) that are typically very difficult for individual investigators to support. We are committed to an integrated approach to the study of pain because major breakthroughs in this field can only be achieved through multidisciplinary approaches, and thus will incorporate and facilitate interactions between [1] laboratories (horizontal integration) and [2] researchers and clinicians (vertical integration). Accordingly, horizontal and vertical integration will be essential components of this training program, which will consist of three core elements: 1) Research - Multidisciplinary research projects will not only be encouraged, but expected, as will exposure to clinical management of pain/pain-related problems. These integrations will be achieved through formation of multidisciplinary mentoring committees which will include at least one clinical faculty member among a four-member committee. 2) Theory - Trainees will participate in four required for-credit courses: Mechanisms and Clinical Presentation of Pain, Pain Journal Club, bi-weekly Current Research on Pain presentations, a new course Pain Models - Rationale, Testing and Interpretation as well as the monthly Pain Seminar Series, where trainees interact with prominent pain researchers. 3) Practice - Trainees will be exposed to the assessment, diagnosis and treatment of chronic pain patients through a 2nd new course - Pain Perspectives - that will provide trainees the opportunity to shadow pain physicians as they interview, diagnose and manage chronic pain patients within the Pain Medicine Program at the University of Pittsburgh Medical Center.