Prescription Opioid Addiction: Neurobiological Mechanisms

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DESCRIPTION (provided by applicant): A major and growing problem in the field of drug abuse is prescription opioid abuse and dependence, which has reached epidemic proportions. A major question is whether there are any unique pharmacodynamics or neuroadaptations to explain this epidemic. One largely unexplored hypothesis to explain the high abuse potential of the prescription opioid medicines such as oxycodone is that there are neurobiological vulnerabilities in response to chronic administration of these drugs that predispose individuals to addiction on such opioids and that these neurobiological vulnerabilities are exaggerated by the pharmacodynamics of certain synthetic opioids. To test this hypothesis, in the present proposal, individual differences in compulsive drug seeking and dependence will be correlated with individual neuroadaptational changes in brain stress systems known to drive dependence. In Specific Aim 1, animal models of compulsive drug seeking and dependence will be developed for oxycodone and compared to drug seeking for heroin and buprenorphine. Using such animal models, individual differences in compulsive drug seeking, withdrawal and re-escalation of compulsive drug seeking will be characterized. In parallel, in Specific Aim 2 dysregulation of neural systems known to drive the development of compulsive opioid seeking will be characterized. These include alteration of the brain corticotropin releasing factor (CRF) systems and brain dynorphin kappa systems in brain reward and stress circuits. Finally, in Specific Aim 3 microinjection of antagonists of the CRF system and the kappa system in specific brain regions and gene silencing of specific CRF and dynorphin neurocircuits will be employed to reverse neuroadaptive changes and consequent re-escalation of drug seeking in subgroups of rats with high levels of compulsive drug seeking. The present proposal will go far towards elucidating the neurobiological systems within specific neurobiological circuits of the ventral striatum and extended amygdala, which are critical for the motivational aspects of prescription opioid abuse and dependence. The present proposal also will provide important information for identifying novel non- mu opioid treatments for opioid addiction.