51
|
Rogala B, Li Y, Li S, Chen X, Kirouac GJ. Effects of a post-shock injection of the kappa opioid receptor antagonist norbinaltorphimine (norBNI) on fear and anxiety in rats. PLoS One 2012; 7:e49669. [PMID: 23166745 PMCID: PMC3498224 DOI: 10.1371/journal.pone.0049669] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 10/12/2012] [Indexed: 11/18/2022] Open
Abstract
Exposure of rats to footshocks leads to an enduring behavioral state involving generalized fear responses and avoidance. Recent evidence suggests that the expression of negative emotional behaviors produced by a stressor is in part mediated by dynorphin and its main receptor, the kappa opioid receptor (KOR). The purpose of this study was to determine if a subcutaneous injection of the long-acting KOR antagonist norbinaltorphimine (norBNI; 15.0 and 30.0 mg/kg) given 2 days after an acute exposure of rats to footshooks (5×2 s episodes of 1.5 mA delivered over 5 min) attenuates the expression of lasting fear and anxiety. We report that exposure of rats to acute footshock produced long-lasting (>4 weeks) fear (freezing) and anxiety (avoidance of an open area in the defensive withdrawal test). The 30 mg dose of norBNI attenuated the fear expressed when shock rats were placed in the shock context at Day 9 but not Day 27 post-shock. The same dose of norBNI had no effect on the expression of generalized fear produced when shock rats were placed in a novel chamber at Days 8 and 24. In contrast, the 30 mg dose of norBNI produced consistent anxiolytic effects in shock and nonshock rats. First, the 30 mg dose was found to decrease the latency to enter the open field in the defensive withdrawal test done 30 days after the shock exposure. Second, the same high dose also had anxiolytic effects in both nonshock and shock rats as evidence by a decrease in the mean time spent in the withdrawal box. The present study shows that systemic injection of the KOR antagonist norBNI had mixed effect on fear. In contrast, norBNI had an anxiolytic effect which included the attenuation of the enhanced avoidance of a novel area produced by a prior shock experience.
Collapse
Affiliation(s)
- Benjamin Rogala
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Yonghui Li
- Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Sa Li
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xiaoyu Chen
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Gilbert J. Kirouac
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Psychiatry, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
| |
Collapse
|
52
|
Feng Y, He X, Yang Y, Chao D, Lazarus LH, Xia Y. Current research on opioid receptor function. Curr Drug Targets 2012; 13:230-46. [PMID: 22204322 DOI: 10.2174/138945012799201612] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/09/2011] [Accepted: 08/12/2011] [Indexed: 12/11/2022]
Abstract
The use of opioid analgesics has a long history in clinical settings, although the comprehensive action of opioid receptors is still less understood. Nonetheless, recent studies have generated fresh insights into opioid receptor-mediated functions and their underlying mechanisms. Three major opioid receptors (μ-opioid receptor, MOR; δ-opioid receptor, DOR; and κ-opioid receptor, KOR) have been cloned in many species. Each opioid receptor is functionally sub-classified into several pharmacological subtypes, although, specific gene corresponding each of these receptor subtypes is still unidentified as only a single gene has been isolated for each opioid receptor. In addition to pain modulation and addiction, opioid receptors are widely involved in various physiological and pathophysiological activities, including the regulation of membrane ionic homeostasis, cell proliferation, emotional response, epileptic seizures, immune function, feeding, obesity, respiratory and cardiovascular control as well as some neurodegenerative disorders. In some species, they play an essential role in hibernation. One of the most exciting findings of the past decade is the opioid-receptor, especially DOR, mediated neuroprotection and cardioprotection. The upregulation of DOR expression and DOR activation increase the neuronal tolerance to hypoxic/ischemic stress. The DOR signal triggers (depending on stress duration and severity) different mechanisms at multiple levels to preserve neuronal survival, including the stabilization of homeostasis and increased pro-survival signaling (e.g., PKC-ERK-Bcl 2) and antioxidative capacity. In the heart, PKC and KATP channels are involved in the opioid receptor-mediated cardioprotection. The DOR-mediated neuroprotection and cardioprotection have the potential to significantly alter the clinical pharmacology in terms of prevention and treatment of life-threatening conditions like stroke and myocardial infarction. The main purpose of this article is to review the recent work done on opioids and their receptor functions. It shall provide an informative reference for better understanding the opioid system and further elucidation of the opioid receptor function from a physiological and pharmacological point of view.
Collapse
Affiliation(s)
- Yuan Feng
- Yale University School of Medicine, New Haven, CT, USA
| | | | | | | | | | | |
Collapse
|
53
|
Abstract
The prairie vole is a socially monogamous species in which breeder pairs typically show strong and selective pair bonds. The establishment of a pair bond is associated with a behavioral transition from general affiliation to aggressive rejection of novel conspecifics. This "selective aggression" is indicative of mate guarding that is necessary to maintain the initial pair bond. In the laboratory, the neurobiology of this behavior is studied using resident-intruder testing. Although it is well established that social behaviors in other species are mediated by endogenous opioid systems, opiate regulation of pair bond maintenance has never been studied. Here, we used resident-intruder testing to determine whether endogenous opioids within brain motivational circuitry mediate selective aggression in prairie voles. We first show that peripheral blockade of κ-opioid receptors with the antagonist norbinaltorphimine (nor-BNI; 100 mg/kg), but not with the preferential μ-opioid receptor antagonist naloxone (1, 10, or 30 mg/kg), decreased selective aggression in males. We then provide the first comprehensive characterization of κ- and μ-opioid receptors in the prairie vole brain. Finally, we demonstrate that blockade of κ-opioid receptors (500 ng nor-BNI) within the nucleus accumbens (NAc) shell abolishes selective aggression in both sexes, but blockade of these receptors within the NAc core enhances this behavior specifically in females. Blockade of κ-opioid receptors within the ventral pallidum or μ-opioid receptors with the specific μ-opioid receptor antagonist H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-PenThr-NH2 (1 ng CTAP) within the NAc shell had no effect in either sex. Thus, κ-opioid receptors within the NAc shell mediate aversive social motivation that is critical for pair bond maintenance.
Collapse
|
54
|
Butelman ER, Yuferov V, Kreek MJ. κ-opioid receptor/dynorphin system: genetic and pharmacotherapeutic implications for addiction. Trends Neurosci 2012; 35:587-96. [PMID: 22709632 DOI: 10.1016/j.tins.2012.05.005] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/27/2012] [Accepted: 05/17/2012] [Indexed: 11/17/2022]
Abstract
Addictions to cocaine or heroin/prescription opioids [short-acting μ-opioid receptor (MOPr) agonists] involve relapsing cycles, with experimentation/escalating use, withdrawal/abstinence, and relapse/re-escalation. κ-Opioid receptors (KOPr; encoded by OPRK1), and their endogenous agonists, the dynorphins (encoded by PDYN), have counter-modulatory effects on reward caused by cocaine or MOPr agonist exposure, and exhibit plasticity in addictive-like states. KOPr/dynorphin activation is implicated in depression/anxiety, often comorbid with addictions. In this opinion article we propose that particular stages of the addiction cycle are differentially affected by KOPr/dynorphin systems. Vulnerability and resilience can be due to pre-existing (e.g., genetic) factors, or epigenetic modifications of the OPRK1 or PDYN genes during the addiction cycle. Pharmacotherapeutic approaches limiting changes in KOPr/dynorphin tone, especially with KOPr partial agonists, may hold potential for the treatment of specific drug addictions and psychiatric comorbidity.
Collapse
MESH Headings
- Adaptation, Biological/genetics
- Adaptation, Biological/physiology
- Animals
- Behavior, Addictive/drug therapy
- Behavior, Addictive/genetics
- Behavior, Addictive/physiopathology
- Disease Models, Animal
- Drug Discovery/methods
- Dynorphins/physiology
- Enkephalins/genetics
- Genetic Predisposition to Disease/genetics
- Humans
- Illicit Drugs/pharmacology
- Narcotic Antagonists/pharmacology
- Narcotic Antagonists/therapeutic use
- Polymorphism, Genetic
- Protein Precursors/genetics
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/physiology
- Recurrence
Collapse
Affiliation(s)
- Eduardo R Butelman
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | | | | |
Collapse
|
55
|
Yuan Y, Elbegdorj O, Chen J, Akubathini SK, Beletskaya IO, Selley DE, Zhang Y. Structure selectivity relationship studies of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan derivatives toward the development of the mu opioid receptor antagonists. Bioorg Med Chem Lett 2011; 21:5625-9. [PMID: 21788135 PMCID: PMC3171173 DOI: 10.1016/j.bmcl.2011.06.135] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 06/07/2011] [Accepted: 06/10/2011] [Indexed: 10/18/2022]
Abstract
Mu opioid receptor antagonists have been applied to target a variety of diseases clinically. The current study is designed to explore the structure selectivity relationship (SSR) of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan (NAP), a lead compound identified as a selective mu opioid receptor antagonist based on the previous study. Among a series of NAP derivatives synthesized, compounds 6 (NMP) and 9 (NGP) maintained comparable binding affinity, selectivity and efficacy to the lead compound. Particularly, the mu opioid receptor selectivity over kappa opioid receptor of NGP was considerably enhanced compared to that of NAP. Overall, the preliminary SSR supported our original hypothesis that an alternate 'address' domain may exist in the mu opioid receptor, which favors the ligands carrying a hydrogen bond acceptor and an aromatic system to selectively recognize the mu opioid receptor.
Collapse
Affiliation(s)
- Yunyun Yuan
- Department of Medicinal Chemistry, Virginia Commonwealth University, Biotech I, 800 E. Leigh Street, Richmond, VA 23298
| | - Orgil Elbegdorj
- Department of Medicinal Chemistry, Virginia Commonwealth University, Biotech I, 800 E. Leigh Street, Richmond, VA 23298
| | - Jianyang Chen
- Department of Medicinal Chemistry, Virginia Commonwealth University, Biotech I, 800 E. Leigh Street, Richmond, VA 23298
| | - Shashidhar K. Akubathini
- Department of Medicinal Chemistry, Virginia Commonwealth University, Biotech I, 800 E. Leigh Street, Richmond, VA 23298
| | - Irina O. Beletskaya
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 North 12th Street, Richmond, VA 23298
| | - Dana E. Selley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 North 12th Street, Richmond, VA 23298
| | - Yan Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University, Biotech I, 800 E. Leigh Street, Richmond, VA 23298
| |
Collapse
|
56
|
Sauriyal DS, Jaggi AS, Singh N. Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states. Neuropeptides 2011; 45:175-88. [PMID: 21208657 DOI: 10.1016/j.npep.2010.12.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
Abstract
Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.
Collapse
|
57
|
Cole S, Richardson R, McNally GP. Kappa opioid receptors mediate where fear is expressed following extinction training. Learn Mem 2011; 18:88-95. [PMID: 21245209 DOI: 10.1101/lm.2049511] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Six experiments used a within-subjects renewal design to examine the involvement of kappa opioid receptors (KORs) in regulating the expression and recovery of extinguished fear. Rats were trained to fear a tone conditioned stimulus (CS) via pairings with foot shock in a distinctive context (A). This was followed by extinction training of the CS in a second context (B). Finally, all rats were tested for fear to the tone in the extinction context (ABB) and the training (ABA) or a novel (ABC) context. Intracerebroventricular (ICV) infusion of the KOR antagonist nor-binaltorphimine dihydrochloride (nor-BNI) dose-dependently prevented ABA renewal of fear, but had no effect on the expression of ABC renewal, the expression of extinction, or the expression of nonextinguished fear. Conversely, pretest infusion of the KOR agonist U50,488 hydrochloride (U50,488) selectively facilitated the expression of ABA renewal and had no effect on the expression of extinction. Pretest infusion of nor-BNI had no effect on the expression of context-specific latent inhibition. Collectively, these results suggest that KORs gate the expression of fear following extinction training and may comprise a critical neuropeptide component of the circuitry underlying context-dependent expression of fear.
Collapse
Affiliation(s)
- Sindy Cole
- School of Psychology, The University of New South Wales, Sydney 2052, Australia
| | | | | |
Collapse
|
58
|
Runyon SP, Brieaddy LE, Mascarella SW, Thomas JB, Navarro HA, Howard JL, Pollard GT, Carroll FI. Analogues of (3R)-7-hydroxy-N-[(1S)-1-{[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-2-methylpropyl)-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide (JDTic). Synthesis and in vitro and in vivo opioid receptor antagonist activity. J Med Chem 2010; 53:5290-301. [PMID: 20568781 DOI: 10.1021/jm1004978] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of compounds 6, 7a,b, 8a,b, 9a,b, and 10a,b where the amino -NH- group of JDTic (3) was replaced with an aromatic horizontal lineCH-, CH(2), O, S, or SO group was accomplished and used to further characterize the SAR of the compound 3 class of kappa opioid receptor antagonists. All of the compounds showed subnanomolar to low nanomolar K(e) values at the kappa opioid receptor. The most potent compound was 7a, where the amino -NH- group of 3 was replaced by a methylene (-CH(2)-) group. This compound had a K(e) = 0.18 nM and was 37- and 248-fold selective for the kappa relative to the mu and delta opioid receptors, respectively. Similar to compound 3, compound 7a antagonized selective kappa agonist U50,488-induced diuresis after sc administration in rats. In contrast to 3, where kappa antagonist activity lasted for three weeks, compound 7a did not show any kappa antagonist activity after one week.
Collapse
Affiliation(s)
- Scott P Runyon
- Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | | | | | |
Collapse
|
59
|
Carr GV, Bangasser DA, Bethea T, Young M, Valentino RJ, Lucki I. Antidepressant-like effects of kappa-opioid receptor antagonists in Wistar Kyoto rats. Neuropsychopharmacology 2010; 35:752-63. [PMID: 19924112 PMCID: PMC2813986 DOI: 10.1038/npp.2009.183] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Wistar Kyoto (WKY) rat strain is a putative genetic model of comorbid depression and anxiety. Previous research showing increased kappa-opioid receptor (KOR) gene expression in the brains of WKY rats, combined with studies implicating the KOR in animal models of depression and anxiety, suggests that alterations in the KOR system could have a role in the WKY behavioral phenotype. Here, the effects of KOR antagonists in the forced swim test (FST) were compared with the WKY and the Sprague-Dawley (SD) rat strains. As previously reported, WKY rats showed more immobility behavior than SD rats. The KOR antagonists selectively produced antidepressant-like effects in the WKY rats. By contrast, the antidepressant desipramine reduced immobility in both strains. Brain regions potentially underlying the strain-specific effects of KOR antagonists in the FST were identified using c-fos expression as a marker of neuronal activity. The KOR antagonist nor-binaltorphimine produced differential effects on the number of c-fos-positive profiles in the piriform cortex and nucleus accumbens shell between SD and WKY rats. The piriform cortex and nucleus accumbens also contained higher levels of KOR protein and dynorphin A peptide, respectively, in the WKY strain. In addition, local administration of nor-binaltorphimine directly into the piriform cortex produced antidepressant-like effects in WKY rats further implicating this region in the antidepressant-like response to KOR antagonists. These results support the use of the WKY rat as a model of affective disorders potentially involving KOR overactivity and provide more evidence that KOR antagonists could potentially be used as novel antidepressants.
Collapse
Affiliation(s)
- Gregory V Carr
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA, USA
| | - Debra A Bangasser
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Thelma Bethea
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Matthew Young
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA, USA
| | - Rita J Valentino
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Irwin Lucki
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA, USA,Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, USA,Department of Psychiatry, University of Pennsylvania, 125 South 31st Street, Room 2204, Philadelphia, PA 19104, USA. Tel: +1 215 573 3305; Fax: +1 215 573 2149; E-mail:
| |
Collapse
|
60
|
Patkar KA, Murray TF, Aldrich JV. The effects of C-terminal modifications on the opioid activity of [N-benzylTyr(1)]dynorphin A-(1-11) analogues. J Med Chem 2009; 52:6814-21. [PMID: 19807094 DOI: 10.1021/jm900715m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structural modifications affecting the efficacy of analogues of the endogenous opioid peptide dynorphin (Dyn) A have focused on the N-terminal "message" sequence based on the "message-address" concept. To test the hypothesis that changes in the C-terminal "address" domain could affect efficacy, modified amino acids and cyclic constraints were incorporated into this region of the partial agonist [N-benzylTyr(1)]Dyn A-(1-11). Modifications in the C-terminal domain of [N-benzylTyr(1)]Dyn A-(1-11)NH(2) resulted in increased kappa opioid receptor (KOR) affinity for all of the linear analogues but did not affect the efficacy of these peptides at KOR. Cyclization between positions 5 and 8 yielded [N-benzylTyr(1),cyclo(d-Asp(5),Dap(8))]Dyn A-(1-11)NH(2) (zyklophin, 13) ( J. Med. Chem. 2005 , 48 , 4500 - 4503 ) with high selectivity for KOR. In contrast to the linear peptides, this peptide exhibits negligible efficacy in the adenylyl cyclase (AC) assay and is a KOR antagonist. These data are consistent with our hypothesis that appropriate modifications in the "address" domain of Dyn A analogues may affect efficacy.
Collapse
Affiliation(s)
- Kshitij A Patkar
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
| | | | | |
Collapse
|
61
|
Zyklophin, a systemically active selective kappa opioid receptor peptide antagonist with short duration of action. Proc Natl Acad Sci U S A 2009; 106:18396-401. [PMID: 19841255 DOI: 10.1073/pnas.0910180106] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cyclic peptide zyklophin {[N-benzylTyr(1),cyclo(D-Asp(5),Dap(8))-dynorphin A-(1-11)NH(2), Patkar KA, et al. (2005) J Med Chem 48: 4500-4503} is a selective peptide kappa opioid receptor (KOR) antagonist that shows activity following systemic administration. Systemic (1-3 mg/kg s.c.) as well as central (0.3-3 nmol intracerebroventricular, i.c.v.) administration of this peptide dose-dependently antagonizes the antinociception induced by the selective KOR agonist U50,488 in C57BL/6J mice tested in the 55 degrees C warm water tail withdrawal assay. Zyklophin administration had no effect on morphine- or SNC-80-mediated antinociception, suggesting that zyklophin selectively antagonizes KOR in vivo. Additionally, the antagonism of antinociception induced by centrally (i.c.v.) administered U50,488 following peripheral administration of zyklophin strongly suggests that the peptide crosses the blood-brain barrier to antagonize KOR in the CNS. Most importantly, the antagonist activity of zyklophin (3 mg/kg s.c.) lasts less than 12 h, which contrasts sharply with the exceptionally long duration of antagonism reported for the established small-molecule selective KOR antagonists such as nor-binaltorphimine (nor-BNI) that last weeks after a single administration. Systemically administered zyklophin (3 mg/kg s.c.) also prevented stress-induced reinstatement of cocaine-seeking behavior in a conditioned place preference assay. In conclusion, the peptide zyklophin is a KOR-selective antagonist that exhibits the desired shorter duration of action, and represents a significant advance in the development of KOR-selective antagonists.
Collapse
|
62
|
Dynorphin, stress, and depression. Brain Res 2009; 1314:56-73. [PMID: 19782055 DOI: 10.1016/j.brainres.2009.09.074] [Citation(s) in RCA: 351] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 09/14/2009] [Accepted: 09/17/2009] [Indexed: 12/29/2022]
Abstract
Stress is most often associated with aversive states. It rapidly induces the release of hormones and neuropeptides including dynorphin, which activates kappa opioid receptors (KORs) in the central and peripheral nervous systems. In animal models, many aversive effects of stress are mimicked or exacerbated by stimulation of KORs in limbic brain regions. Although KOR signaling during acute stress may increase physical ability (by producing analgesia) and motivation to escape a threat (by producing aversion), prolonged KOR signaling in response to chronic or uncontrollable stress can lead to persistent expression of behavioral signs that are characteristic of human depressive disorders (i.e., "prodepressive-like" signs). Accumulating evidence suggests that KORs contribute to the progressive amplification (sensitization) of stress-induced behaviors that occurs with repeated exposure to stress. Many of the aversive effects of stress are blocked by KOR antagonists, suggesting that these agents may have potential as therapeutics for stress-related conditions such as depression and anxiety disorders. This review summarizes current data on how KOR systems contribute to the acute (rapid), delayed, and cumulative molecular and behavioral effects of stress. We focus on behavioral paradigms that provide insight on interactions between stress and KOR function within each of these temporal categories. Using a simplified model, we consider the time course and mechanism of KOR-mediated effects in stress and suggest future directions that may be useful in determining whether KOR antagonists exert their therapeutic effects by preventing the development of stress-induced behaviors, the expression of stress-induced behaviors, or both.
Collapse
|
63
|
Schwarzer C. 30 years of dynorphins--new insights on their functions in neuropsychiatric diseases. Pharmacol Ther 2009; 123:353-70. [PMID: 19481570 DOI: 10.1016/j.pharmthera.2009.05.006] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 05/13/2009] [Indexed: 11/28/2022]
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.
Collapse
Affiliation(s)
- Christoph Schwarzer
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr-Str. 1a, A-6020 Innsbruck, Austria.
| |
Collapse
|
64
|
Wiley MD, Poveromo LB, Antapasis J, Herrera CM, Bolaños-Guzmán CA. Kappa-opioid system regulates the long-lasting behavioral adaptations induced by early-life exposure to methylphenidate. Neuropsychopharmacology 2009; 34:1339-50. [PMID: 18923399 PMCID: PMC2656574 DOI: 10.1038/npp.2008.188] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Methylphenidate (MPH) is commonly prescribed in childhood and adolescence for the treatment of attention-deficit/hyperactivity disorders. In rodents, MPH exposure during preadolescence (postnatal days (PD) 20-35) causes decreased sensitivity to drug and natural rewards, while enhancing a negative emotional state characterized by increased sensitivity to aversive situations later in adulthood. It has been proposed that this behavioral profile may be mediated, at least in part, by changes in the expression of dynorphin, the endogenous ligand for kappa-opioid receptors (KORs). Because increases in dynorphin activity and activation of KOR induce aversive states, we examined the possibility that these behavioral deficits may be mediated by changes in KOR function, and that MPH-exposed rats would demonstrate increased sensitivity to the kappa-agonist U-50488. Sprague-Dawley male rats were treated with MPH (2 mg/kg) or its saline vehicle (VEH) during PD20-35. When adults (PD90+), these rats were divided into groups receiving saline, U-50488 (5 mg/kg), or nor-binaltorphimine (20 mg/kg), a kappa-antagonist, and their behavioral reactivity to various emotion-eliciting stimuli was assessed. Results show that MPH exposure decreases cocaine place conditioning and sucrose preference, while increasing vulnerability to anxiety (elevated plus maze)- and stress (forced swimming)-eliciting situations, and that these behavioral deficits can be intensified by U-50488, while being normalized by nor-binaltorphimine treatment. These results are consistent with the notion that dysregulated dynorphin/kappa-opioid systems may mediate deficits in behavioral responding after developmental MPH exposure. Moreover, these findings further support the idea of kappa-antagonists as potential pharmacotherapy for the treatment of anxiety- and depression-related disorders.
Collapse
Affiliation(s)
| | | | | | | | - Carlos A. Bolaños-Guzmán
- Corresponding author: Dr. CA Bolaños. Department of Psychology and Program in Neuroscience, Florida State University, 1107 West Call Street, P.O. Box 3064301, Tallahassee, FL 32306-4301. Tel: (850) 644-2627; Fax (850) 645-7518;
| |
Collapse
|
65
|
Boettiger CA, Kelley EA, Mitchell JM, D'Esposito M, Fields HL. Now or Later? An fMRI study of the effects of endogenous opioid blockade on a decision-making network. Pharmacol Biochem Behav 2009; 93:291-9. [PMID: 19258022 DOI: 10.1016/j.pbb.2009.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 02/02/2009] [Accepted: 02/13/2009] [Indexed: 12/12/2022]
Abstract
Previously, we found that distinct brain areas predict individual selection bias in decisions between small immediate ("Now") and larger delayed rewards ("Later"). Furthermore, such selection bias can be manipulated by endogenous opioid blockade. To test whether blocking endogenous opioids with naltrexone (NTX) alters brain activity during decision-making in areas predicting individual bias, we compared fMRI BOLD signal correlated with Now versus Later decision-making after acute administration of NTX (50 mg) or placebo. We tested abstinent alcoholics and control subjects in a double-blind two-session design. We defined regions of interest (ROIs) centered on activation peaks predicting Now versus Later selection bias. NTX administration significantly increased BOLD signal during decision-making in the right lateral orbital gyrus ROI, an area where enhanced activity during decision-making predicts Later bias. Exploratory analyses identified additional loci where BOLD signal during decision-making was enhanced (left orbitofrontal cortex, left inferior temporal gyrus, and cerebellum) or reduced (right superior temporal pole) by NTX. Additional analyses identified sites, including the right lateral orbital gyrus, in which NTX effects on BOLD signal predicted NTX effects on selection bias. These data agree with opioid receptor expression in human frontal and temporal cortices, and suggest possible mechanisms of NTX's therapeutic effects.
Collapse
Affiliation(s)
- Charlotte A Boettiger
- Department of Psychology, Biomedical Research Imaging Center, University of North Carolina, Chapel Hill 27599-3270, United States.
| | | | | | | | | |
Collapse
|
66
|
Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
Collapse
Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
| |
Collapse
|
67
|
Mendelson J, Flower K, Pletcher M, Galloway GP. Addiction to prescription opioids: characteristics of the emerging epidemic and treatment with buprenorphine. Exp Clin Psychopharmacol 2008; 16:435-41. [PMID: 18837640 PMCID: PMC4687728 DOI: 10.1037/a0013637] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dependence on and abuse of prescription opioid drugs is now a major health problem, with initiation of prescription opioid abuse exceeding cocaine in young people. Coincident with the emergence of abuse and dependence on prescription opioids, there has been an increased emphasis on the treatment of pain. Pain is now the "5th vital sign" and physicians face disciplinary action for failure to adequately relieve pain. Thus, physicians are whipsawed between the imperative to treat pain with opioids and the fear of producing addiction in some patients. In this article, the authors characterize the emerging epidemic of prescription opioid abuse, discuss the utility of buprenorphine in the treatment of addiction to prescription opioids, and present illustrative case histories of successful treatment with buprenorphine.
Collapse
Affiliation(s)
- John Mendelson
- California Pacific Medical Center Research Institute, St. Luke's Hospital, and Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, CA 94110, USA.
| | - Keith Flower
- Addiction Pharmacology Research Laboratory, California Pacific Medical Center Research Institute, St Luke’s Hospital, 3555 Cesar Chavez, San Francisco, CA 94110, 415-641-2105, 415-641-3380 fax
| | - Mark Pletcher
- Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, CA 94143
| | - Gantt P. Galloway
- Addiction Pharmacology Research Laboratory, California Pacific Medical Center Research Institute, St Luke’s Hospital, 3555 Cesar Chavez, San Francisco, CA 94110, 415-641-2105, 415-641-3380 fax
| |
Collapse
|
68
|
|