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Abstract
Acute activation of kappa-opioid receptors produces anti-addictive effects by regulating dopamine levels in the brain. Unfortunately, classic kappa-opioid agonists have undesired side effects such as sedation, aversion, and depression, which restrict their clinical use. Salvinorin A (Sal A), a novel kappa-opioid receptor agonist extracted from the plant Salvia divinorum, has been identified as a potential therapy for drug abuse and addiction. Here, we review the preclinical effects of Sal A in comparison with traditional kappa-opioid agonists and several new analogs. Sal A retains the anti-addictive properties of traditional kappa-opioid receptor agonists with several improvements including reduced side effects. However, the rapid metabolism of Sal A makes it undesirable for clinical development. In an effort to improve the pharmacokinetics and tolerability of this compound, kappa-opioid receptor agonists based on the structure of Sal A have been synthesized. While work in this field is still in progress, several analogs with improved pharmacokinetic profiles have been shown to have anti-addictive effects. While in its infancy, it is clear that these compounds hold promise for the future development of anti-addictive therapeutics.
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Affiliation(s)
- Bronwyn M Kivell
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Amy W M Ewald
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Thomas E Prisinzano
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas, USA.
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2
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Yan J, Li J, Yan J, Sun H, Wang Q, Chen K, Sun B, Wei X, Song L, Zhao X, Wei S, Han L. Activation of μ-opioid receptors in the central nucleus of the amygdala induces hypertonic sodium intake. Neuroscience 2013; 233:28-43. [DOI: 10.1016/j.neuroscience.2012.12.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 12/13/2012] [Accepted: 12/15/2012] [Indexed: 12/29/2022]
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3
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Briand LA, Blendy JA. Molecular and genetic substrates linking stress and addiction. Brain Res 2009; 1314:219-34. [PMID: 19900417 DOI: 10.1016/j.brainres.2009.11.002] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 11/02/2009] [Accepted: 11/03/2009] [Indexed: 12/19/2022]
Abstract
Drug addiction is one of the top three health concerns in the United States in terms of economic and health care costs. Despite this, there are very few effective treatment options available. Therefore, understanding the causes and molecular mechanisms underlying the transition from casual drug use to compulsive drug addiction could aid in the development of treatment options. Studies in humans and animal models indicate that stress can lead to both vulnerability to develop addiction, and increased drug taking and relapse in addicted individuals. Exposure to stress or drugs of abuse results in long-term adaptations in the brain that are likely to involve persistent alterations in gene expression or activation of transcription factors, such as the cAMP Response Element Binding (CREB) protein. The signaling pathways controlled by CREB have been strongly implicated in drug addiction and stress. Many potential CREB target genes have been identified based on the presence of a CRE element in promoter DNA sequences. These include, but are not limited to CRF, BDNF, and dynorphin. These genes have been associated with initiation or reinstatement of drug reward and are altered in one direction or the other following stress. While many reviews have examined the interactions between stress and addiction, the goal of this review was to focus on specific molecules that play key roles in both stress and addiction and are therefore posed to mediate the interaction between the two. Focus on these molecules could provide us with new targets for pharmacological treatments for addiction.
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Affiliation(s)
- Lisa A Briand
- Department of Pharmacology, The University of Pennsylvania School of Medicine, TRL, 125 South 31(st) Street, USA
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4
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Abstract
Since the first description of their opioid properties three decades ago, dynorphins have increasingly been thought to play a regulatory role in numerous functional pathways of the brain. Dynorphins are members of the opioid peptide family and preferentially bind to kappa opioid receptors. In line with their localization in the hippocampus, amygdala, hypothalamus, striatum and spinal cord, their functions are related to learning and memory, emotional control, stress response and pain. Pathophysiological mechanisms that may involve dynorphins/kappa opioid receptors include epilepsy, addiction, depression and schizophrenia. Most of these functions were proposed in the 1980s and 1990s following histochemical, pharmacological and electrophysiological experiments using kappa receptor-specific or general opioid receptor agonists and antagonists in animal models. However, at that time, we had little information on the functional relevance of endogenous dynorphins. This was mainly due to the complexity of the opioid system. Besides actions of peptides from all three classical opioid precursors (proenkephalin, prodynorphin, proopiomelanocortin) on the three classical opioid receptors (delta, mu and kappa), dynorphins were also shown to exert non-opioid effects mainly through direct effects on NMDA receptors. Moreover, discrepancies between the distribution of opioid receptor binding sites and dynorphin immunoreactivity contributed to the difficulties in interpretation. In recent years, the generation of prodynorphin- and opioid receptor-deficient mice has provided the tools to investigate open questions on network effects of endogenous dynorphins. This article examines the physiological, pathophysiological and pharmacological implications of dynorphins in the light of new insights in part obtained from genetically modified animals.
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Affiliation(s)
- Christoph Schwarzer
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr-Str. 1a, A-6020 Innsbruck, Austria.
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5
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Abstract
Drug addiction is a chronic relapsing disease in which drug administration becomes the primary stimulus that drives behavior regardless of the adverse consequence that may ensue. As drug use becomes more compulsive, motivation for natural rewards that normally drive behavior decreases. The discontinuation of drug use is associated with somatic signs of withdrawal, dysphoria, anxiety, and anhedonia. These consequences of drug use are thought to contribute to the maintenance of drug use and to the reinstatement of compulsive drug use that occurs during the early phase of abstinence. Even, however, after prolonged periods of abstinence, 80-90% of human addicts relapse to addiction, suggesting that repeated drug use produces enduring changes in brain circuits that subserve incentive motivation and stimulus-response (habit) learning. A major goal of addiction research is the identification of the neural mechanisms by which drugs of abuse produce these effects. This article will review data showing that the dynorphin/kappa-opioid receptor (KOPr) system serves an essential function in opposing alterations in behavior and brain neurochemistry that occur as a consequence of repeated drug use and that aberrant activity of this system may not only contribute to the dysregulation of behavior that characterizes addiction but to individual differences in vulnerability to the pharmacological actions of cocaine and alcohol. We will provide evidence that the repeated administration of cocaine and alcohol up-regulates the dynorphin/KOPr system and that pharmacological treatments that target this system may prove effective in the treatment of drug addiction.
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Affiliation(s)
- T S Shippenberg
- Integrative Neuroscience Section, NIH/NIDA Intramural Research Program, 333 Cassell Drive, Baltimore, MD 21224, USA.
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Wilson JD, Nicklous DM, Aloyo VJ, Simansky KJ. An orexigenic role for mu-opioid receptors in the lateral parabrachial nucleus. Am J Physiol Regul Integr Comp Physiol 2003; 285:R1055-65. [PMID: 14557237 DOI: 10.1152/ajpregu.00108.2003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The pontine parabrachial nucleus (PBN) has been implicated in regulating ingestion and contains opioids that promote feeding elsewhere in the brain. We tested the actions of the selective mu-opioid receptor (mu-OR) agonist [d-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAMGO) in the PBN on feeding in male rats with free access to food. Infusing DAMGO (0.5-4.0 nmol/0.5 microl) into the lateral parabrachial region (LPBN) increased food intake. The hyperphagic effect was anatomically specific to infusions within the LPBN, dose and time related, and selective for ingestion of chow compared with (nonnutritive) kaolin. The nonselective opioid antagonist naloxone (0.1-10.0 nmol intra-PBN) antagonized DAMGO-induced feeding, with complete blockade by 1.0 nmol and no effect on baseline. The highly selective mu-opioid antagonist d-Phe-Cys-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP; 1.0 nmol) also prevented this action of DAMGO, but the kappa-antagonist nor-binaltorphimine did not. Naloxone and CTAP (10.0 nmol) decreased intake during scheduled feeding. Thus stimulating mu-ORs in the LPBN increases feeding, whereas antagonizing these sites inhibits feeding. Together, our results implicate mu-ORs in the LPBN in the normal regulation of food intake.
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Affiliation(s)
- John D Wilson
- Dept. of Pharmacology and Physiology, Drexel Univ. College of Medicine, Mailstop 488, 245 N. 15th St., Philadelphia, PA 19102-1192, USA
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Minowa S, Ishihara S, Tsuchiya S, Horie S, Watanabe K, Murayama T. Involvement of glutamate and gamma-amino-butyric acid receptor systems on gastric acid secretion induced by activation of kappa-opioid receptors in the central nervous system in rats. Br J Pharmacol 2003; 138:1049-58. [PMID: 12684260 PMCID: PMC1573744 DOI: 10.1038/sj.bjp.0705082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
1. Various neurotransmitters in the brain regulate gastric acid secretion. Previously, we reported that the central injection of kappa-opioid receptor agonists stimulated this secretion in rats. Although the existence of kappa(1)-kappa(3)-opioid receptor subtypes has been proposed, the character is not defined. We investigated the interactions between kappa-opioid receptor subtypes and glutamate, gamma-amino-butyric acid (GABA) or 5-hydroxy tryptamine (5-HT) receptors in the rat brain. 2. Gastric acid secretion induced by the injection of U69593 (8.41 nmol, a putative kappa(1)-opioid receptor agonist) into the lateral cerebroventricle was completely inhibited by the central injection of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10.9 nmol, an antagonist for non-N-methyl-D-aspartate (non-NMDA) receptors) and by bicuculline infusion (222 micro g kg(-1) per 10 min, i.v., GABA(A) receptor antagonist). The secretion induced by bremazocine (8.52 nmol, a putative kappa(2)-opioid receptor agonist) was inhibited by bicuculline infusion, but not by CNQX. The secretion induced by naloxone benzoylhydrazone (224 nmol, a putative kappa(3)-opioid receptor agonist) was slightly and partially inhibited by CNQX and bicuculline. 3. Treatment with CNQX and bicuculline inhibited gastric acid secretion induced by the injection of dynorphin A-(1-17) into the lateral, but not the fourth, cerebroventricle. Antagonists for NMDA, GABA(B) and 5-HT(2/1C) receptors did not inhibit the secretions by kappa-opioid receptor agonists. 4. In rat brain regions close to the lateral cerebroventricle, kappa-opioid receptor systems (kappa(1)>kappa(3)>>kappa(2)) are regulated by the non-NMDA type of glutamate receptor system, and kappa(1)- and kappa(2)-opioid receptor systems are regulated by the GABA(A) receptor system. The present findings show pharmacological evidence for kappa-opioid receptor subtypes that regulate gastric acid secretion in the rat brain.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Baclofen/analogs & derivatives
- Baclofen/pharmacology
- Benzeneacetamides/pharmacology
- Benzomorphans/pharmacology
- Bicuculline/pharmacology
- Brain/physiology
- Dynorphins/pharmacology
- Gastric Acid/metabolism
- Gastric Acid/physiology
- Injections, Intraventricular
- Ketanserin/pharmacology
- Male
- Perfusion/methods
- Piperazines/pharmacology
- Pyrrolidines/pharmacology
- Rats
- Rats, Wistar
- Receptors, GABA-A
- Receptors, Glutamate/drug effects
- Receptors, Kainic Acid/drug effects
- Receptors, N-Methyl-D-Aspartate
- Receptors, Opioid, kappa/administration & dosage
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/physiology
- Receptors, Serotonin
- Stomach/drug effects
- Stomach/physiopathology
- gamma-Aminobutyric Acid
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Affiliation(s)
- Sachie Minowa
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Satomi Ishihara
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Shizuko Tsuchiya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Syunji Horie
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Kazuo Watanabe
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
- Author for correspondence:
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8
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Abstract
This paper is the twenty-second installment of the annual review of research concerning the opiate system. It summarizes papers published during 1999 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunologic responses.
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Affiliation(s)
- A L Vaccarino
- Department of Psychology, University of New Orleans, New Orleans, LA 70148, USA.
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