The positive reinforcement provided by opiates have been considered as primary factors in promoting drug abuse and dependence. However, opiates also produce a host of "negative" effects which can manifest both during opiate administration and which are particularly expressed during withdrawal. Withdrawal from opiates is unpleasant and may provide negative reinforcement and contribute to drug dependence. Thus, both positive and negative reinforcement are likely to contribute to the compulsive use of opioids, a critical feature of "opioid addiction". The mechanisms by which opiates produce negative effects are unknown. Our preliminary data indicate that blockade of descending facilitation in the rostral ventromedial medulla (RVM) prevents expression of somatic and autonomic signs of opiate withdrawal indicating that facilitatory outflow from the RVM is critical in mediating both nociceptive (i.e., opiate-induced hyperalgesia) and many nonnociceptive features of the withdrawal syndrome. We hypothesize that opiate-induced descending facilitation from the RVM and subsequent upregulation of spinal dynorphin are essential for the expression of many of the negative symptoms which comprise withdrawal from opiates. Mechanisms which underlie the expression of the withdrawal syndrome thus also represent mechanisms likely promote negative reinforcement which may contribute to opiate dependence, the continued use and abuse of opiates and drug seeking behavior. This hypothesis will be explored with four Specific Aims: First, we will characterize pronociceptive transmitters in the RVM in which can mediate naloxone-precipitated withdrawal. Second, we will determine whether prevention of descending facilitation from the RVM prevents opiate-induced physical dependence (naloxone-induced or spontaneous withdrawal). Third, we will determine whether blockade of the pronociceptive actions of spinal dynorphin, or the bradykinin B2 receptor will prevent withdrawal. Fourth, we will determine if blockade of descending facilitation blocks withdrawal-induced aversion/negative reinforcement. These studies assess mechanisms which may contribute to negative reinforcement, drug dependence and abuse.
This project explores the role of adapative changes elicited by opiates which may produce negative reinforcement and contribute to continued drug use and abuse. Understanding these mechanisms may lead to new strategies which may help to counter drug abuse.
|Lee, Yeon Sun; Remesic, Michael; Ramos-Colon, Cyf et al. (2016) Cyclic non-opioid dynorphin A analogues for the bradykinin receptors. Bioorg Med Chem Lett 26:5513-5516|
|Deekonda, Srinivas; Rankin, David; Davis, Peg et al. (2016) Design synthesis and structure-activity relationship of 5-substituted (tetrahydronaphthalen-2yl)methyl with N-phenyl-N-(piperidin-2-yl)propionamide derivatives as opioid ligands. Bioorg Med Chem 24:85-91|
|Hall, Sara M; Lee, Yeon Sun; Hruby, Victor J (2016) Dynorphin A analogs for the treatment of chronic neuropathic pain. Future Med Chem 8:165-77|
|Deekonda, Srinivas; Cole, Jacob; Sunna, Sydney et al. (2016) Enkephalin analogues with N-phenyl-N-(piperidin-2-ylmethyl)propionamide derivatives: Synthesis and biological evaluations. Bioorg Med Chem Lett 26:222-7|
|Lee, Yeon Sun; Kupp, Robert; Remesic, Michael V et al. (2016) Various modifications of the amphipathic dynorphin A pharmacophore for rat brain bradykinin receptors. Chem Biol Drug Des 88:615-9|
|Nair, Padma; Yamamoto, Takashi; Cowell, Scott et al. (2015) Discovery of tripeptide-derived multifunctional ligands possessing delta/mu opioid receptor agonist and neurokinin 1 receptor antagonist activities. Bioorg Med Chem Lett 25:3716-20|
|Cai, Minying; Marelli, Udaya Kiran; Bao, Jennifer et al. (2015) Systematic Backbone Conformational Constraints on a Cyclic Melanotropin Ligand Leads to Highly Selective Ligands for Multiple Melanocortin Receptors. J Med Chem 58:6359-67|
|Mehr-un-Nisa; Munawar, Munawar A; Lee, Yeon Sun et al. (2015) Design, synthesis, and biological evaluation of a series of bifunctional ligands of opioids/SSRIs. Bioorg Med Chem 23:1251-9|
|Giri, Aswini Kumar; Apostol, Christopher R; Wang, Yue et al. (2015) Discovery of Novel Multifunctional Ligands with Î¼/Î´ Opioid Agonist/Neurokinin-1 (NK1) Antagonist Activities for the Treatment of Pain. J Med Chem 58:8573-83|
|Lee, Yeon Sun; Hall, Sara M; Ramos-Colon, Cyf et al. (2015) Blockade of non-opioid excitatory effects of spinal dynorphin A at bradykinin receptors. Receptors Clin Investig 2:|
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