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Abstract
After participating in this activity, learners should be better able to:• Identify the effects of dysregulated opioid signalling in depression• Evaluate the use of opioid compounds and ketamine in patients with depression ABSTRACT: Major depressive disorder (MDD) remains one of the leading causes of disability and functional impairment worldwide. Current antidepressant therapeutics require weeks to months of treatment prior to the onset of clinical efficacy on depressed mood but remain ineffective in treating suicidal ideation and cognitive impairment. Moreover, 30%-40% of individuals fail to respond to currently available antidepressant medications. MDD is a heterogeneous disorder with an unknown etiology; novel strategies must be developed to treat MDD more effectively. Emerging evidence suggests that targeting one or more of the four opioid receptors-mu (MOR), kappa (KOR), delta (DOR), and the nociceptin/orphanin FQ receptor (NOP)-may yield effective therapeutics for stress-related psychiatric disorders. Furthermore, the effects of the rapidly acting antidepressant ketamine may involve opioid receptors. This review highlights dysregulated opioid signaling in depression, evaluates clinical trials with opioid compounds, and considers the role of opioid mechanisms in rapidly acting antidepressants.
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Robayo Avendaño O, Alvira Botero X, Garzón M. Ultrastructural evidence for mu and delta opioid receptors at noradrenergic dendrites and glial profiles in the cat locus coeruleus. Brain Res 2021; 1762:147443. [PMID: 33745926 DOI: 10.1016/j.brainres.2021.147443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 02/01/2021] [Accepted: 03/13/2021] [Indexed: 11/17/2022]
Abstract
The Locus Coeruleus (LC) is a pontine nucleus involved in many physiological processes, including the control of the sleep/wake cycle (SWC). At cellular level, the LC displays a high density of opioid receptors whose activation decreases the activity of LC noradrenergic neurons. Also, microinjections of morphine administered locally in the LC of the cat produce sleep associated with synchronized brain activity in the electroencephalogram (EEG). Even though much of the research on sleep has been done in the cat, the subcellular location of opioid receptors in the LC and their relationship with LC noradrenergic neurons is not known yet in this species. Therefore, we conducted a study to describe the ultrastructural localization of mu-opioid receptors (MOR), delta-opioid receptors (DOR) and tyrosine hydroxylase (TH) in the cat LC using high resolution electron microscopy double-immunocytochemical detection. MOR and DOR were localized mainly in dendrites (45% and 46% of the total number of profiles respectively), many of which were noradrenergic (35% and 53% for MOR and DOR, respectively). TH immunoreactivity was more frequent in dendrites (65% of the total number of profiles), which mostly also expressed opioid receptors (58% and 73% for MOR and DOR, respectively). Because the distribution of MORs and DORs are similar, it is possible that a substantial sub-population of neurons co-express both receptors, which may facilitate the formation of MOR-DOR heterodimers. Moreover, we found differences in the cat subcellular DOR distribution compared with the rat. This opens the possibility to the existence of diverse mechanisms for opioid modulation of LC activity.
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Affiliation(s)
- Omar Robayo Avendaño
- Universidad Pedagógica y Tecnológica de Colombia. Antiguo Hospital San Rafael, 150001 Tunja, Colombia.
| | - Ximena Alvira Botero
- Universidad Autónoma de Madrid, Calle del Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Miguel Garzón
- Universidad Autónoma de Madrid, Calle del Arzobispo Morcillo 4, 28029 Madrid, Spain
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Browne CA, Lucki I. Targeting opioid dysregulation in depression for the development of novel therapeutics. Pharmacol Ther 2019; 201:51-76. [PMID: 31051197 DOI: 10.1016/j.pharmthera.2019.04.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 04/23/2019] [Indexed: 02/07/2023]
Abstract
Since the serendipitous discovery of the first class of modern antidepressants in the 1950's, all pharmacotherapies approved by the Food and Drug Administration for major depressive disorder (MDD) have shared a common mechanism of action, increased monoaminergic neurotransmission. Despite the widespread availability of antidepressants, as many as 50% of depressed patients are resistant to these conventional therapies. The significant length of time required to produce meaningful symptom relief with these medications, 4-6 weeks, indicates that other mechanisms are likely involved in the pathophysiology of depression which may yield more viable targets for drug development. For decades, no viable candidate target with a different mechanism of action to that of conventional therapies proved successful in clinical studies. Now several exciting avenues for drug development are under intense investigation. One of these emerging targets is modulation of endogenous opioid tone. This review will evaluate preclinical and clinical evidence pertaining to opioid dysregulation in depression, focusing on the role of the endogenous ligands endorphin, enkephalin, dynorphin, and nociceptin/orphanin FQ (N/OFQ) and their respective receptors, mu (MOR), delta (DOR), kappa (KOR), and the N/OFQ receptor (NOP) in mediating behaviors relevant to depression and anxiety. Finally, putative opioid based antidepressants that are under investigation in clinical trials, ALKS5461, JNJ-67953964 (formerly LY2456302 and CERC-501) and BTRX-246040 (formerly LY-2940094) will be discussed. This review will illustrate the potential therapeutic value of targeting opioid dysregulation in developing novel therapies for MDD.
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Affiliation(s)
- Caroline A Browne
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America
| | - Irwin Lucki
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America.
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Shim I, Stratford TR, Wirtshafter D. Dopamine is differentially involved in the locomotor hyperactivity produced by manipulations of opioid, GABA and glutamate receptors in the median raphe nucleus. Behav Brain Res 2013; 261:65-70. [PMID: 24333380 DOI: 10.1016/j.bbr.2013.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/30/2013] [Accepted: 12/02/2013] [Indexed: 12/24/2022]
Abstract
The median raphe nucleus (MR) has been shown to exert a powerful influence on behavioral arousal and marked locomotor hyperactivity can be produced by intra-MR injections of a variety of drugs including GABAA and GABAB agonists, excitatory amino acid antagonists, and μ- and δ-opioid agonists. Other studies have indicated that the MR exerts an inhibitory influence on ascending dopamine systems, suggesting that MR induced alterations in activity may be mediated through changes in dopaminergic transmission. In the present study, we explored this possibility by examining whether systemic administration of the preferential D2 dopamine antagonist haloperidol is able to antagonize the hyperactivity produced by intra-MR injections of various drugs. We found that haloperidol completely blocked the locomotor response to intra-MR injections of the μ-opioid receptor agonist DAMGO and the δ-opioid receptor agonist DPDPE. In marked contrast, at doses which abolished the locomotor response to systemic amphetamine, haloperidol had no effect on the hyperactivity induced by intra-MR injections of GABAA agonist muscimol, the GABAB agonist baclofen, or the kainate/quisqualate antagonist pBB-PZDA, even though it suppressed baseline activity in these same animals. These results indicate that there must be at least two mechanisms capable of influencing behavioral arousal within the MR region, one of which is dependent on D2 dopamine receptors and the other is not.
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Affiliation(s)
- Insop Shim
- Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A; AMSRC, Department of Basic Science College of Oriental Medicine, Kyung Hee University, Seoul 130-701, Korea
| | - Thomas R Stratford
- Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A
| | - David Wirtshafter
- Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A.
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Tang B, Li Y, Yuan S, Tomlinson S, He S. Upregulation of the δ opioid receptor in liver cancer promotes liver cancer progression both in vitro and in vivo. Int J Oncol 2013; 43:1281-90. [PMID: 23903826 DOI: 10.3892/ijo.2013.2046] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 06/21/2013] [Indexed: 11/06/2022] Open
Abstract
The δ opioid receptor (DOR), is the first cloned G protein-coupled receptor. Many recent studies on DOR functions have determined that the DOR is involved in the regulation of malignant transformation and tumor progression in multiple cancers. However, it is still unclear if the DOR is involved in the regulation of malignant transformation and tumor progression in hepatocellular carcinoma (HCC). The purpose of our study was to investigate the expression of the DOR in HCC and to determine its effect on progression to further understand the influence of the DOR on the biological characteristics of HCC. Higher expression of DOR was observed in liver tumor tissue/cells compared to normal liver tissue/cells. When DOR gene expression was silenced or inhibited, the proliferation of HCC cells was inhibited, and tumor cells underwent apoptosis, the cell cycle was arrested and tumor cell invasion and migration were significantly decreased. Nude mice inoculated with cells stably expressing low levels of DOR displayed reduced tumor formation rates and reduced tumor growth. In conclusion, DOR is highly expressed in HCC and is involved in HCC progression, suggesting that DOR is a potential target for HCC treatment.
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Affiliation(s)
- Bo Tang
- Department of Hepatobiliary Surgery, Affiliated Hospital, Guilin Medical University, Guilin 541001, Guangxi, P.R. China
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Pharmacological traits of delta opioid receptors: pitfalls or opportunities? Psychopharmacology (Berl) 2013; 228:1-18. [PMID: 23649885 PMCID: PMC3679311 DOI: 10.1007/s00213-013-3129-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/15/2013] [Indexed: 12/11/2022]
Abstract
RATIONALE Delta opioid receptors (DORs) have been considered as a potential target to relieve pain as well as treat depression and anxiety disorders and are known to modulate other physiological responses, including ethanol and food consumption. A small number of DOR-selective drugs are in clinical trials, but no DOR-selective drugs have been approved by the Federal Drug Administration and some candidates have failed in phase II clinical trials, highlighting current difficulties producing effective delta opioid-based therapies. Recent studies have provided new insights into the pharmacology of the DOR, which is often complex and at times paradoxical. OBJECTIVE This review will discuss the existing literature focusing on four aspects: (1) Two DOR subtypes have been postulated based on differences in pharmacological effects of existing DOR-selective ligands. (2) DORs are expressed ubiquitously throughout the body and central nervous system and are, thus, positioned to play a role in a multitude of diseases. (3) DOR expression is often dynamic, with many reports of increased expression during exposure to chronic stimuli, such as stress, inflammation, neuropathy, morphine, or changes in endogenous opioid tone. (4) A large structural variety in DOR ligands implies potential different mechanisms of activating the receptor. CONCLUSION The reviewed features of DOR pharmacology illustrate the potential benefit of designing tailored or biased DOR ligands.
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Cid-Pellitero ED, GarzÓN M. Hypocretin1/OrexinA-containing axons innervate locus coeruleus neurons that project to the Rat medial prefrontal cortex. Implication in the sleep-wakefulness cycle and cortical activation. Synapse 2011; 65:843-57. [DOI: 10.1002/syn.20912] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/09/2010] [Indexed: 12/31/2022]
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Luquin E, Pérez-Lorenzo E, Aymerich MS, Mengual E. Two-color fluorescence labeling in acrolein-fixed brain tissue. J Histochem Cytochem 2010; 58:359-68. [PMID: 20051381 DOI: 10.1369/jhc.2009.954495] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acrolein is a potent fixative that provides both excellent preservation of ultrastructural morphology and retention of antigenicity, thus it is frequently used for immunocytochemical detection of antigens at the electron microscopic level. However, acrolein is not commonly used for fluorescence microscopy because of concerns about possible autofluorescence and destruction of the luminosity of fluorescent dyes. Here we describe a simple protocol that allows fine visualization of two fluorescent markers in 40-mum sections from acrolein-perfused rat brain. Autofluorescence was removed by pretreatment with 1% sodium borohydride for 30 min, and subsequent incubation in a 50% ethanol solution containing 0.3% hydrogen peroxide enhanced fluorescence labeling. Thus, fluorescence labeling can be used for high-quality detection of markers in tissue perfused with acrolein. Furthermore, adjacent acrolein-fixed sections from a single experiment can be processed to produce high-quality results for electron microscopy or fluorescence labeling.
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Affiliation(s)
- Esther Luquin
- Center for Applied Medical Research (CIMA), Area de Neurociencias, Universidad de Navarra, Pamplona, Spain
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Ishida T, Suga A, Akagi M, Kamei C. Effects of Anti-dementia Drugs on Morphine-Induced Somnolence. Biol Pharm Bull 2009; 32:1862-5. [DOI: 10.1248/bpb.32.1862] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Takayuki Ishida
- Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Asami Suga
- Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Masaaki Akagi
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University
| | - Chiaki Kamei
- Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
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Wang Y, Van Bockstaele EJ, Liu-Chen LY. In vivo trafficking of endogenous opioid receptors. Life Sci 2008; 83:693-9. [PMID: 18930741 DOI: 10.1016/j.lfs.2008.09.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/11/2008] [Accepted: 09/17/2008] [Indexed: 12/14/2022]
Abstract
Several approaches have been taken for these in vivo studies. In many studies, the use of semi-quantitative immuno-electron microscopy is the approach of choice. Endogenous opioid receptors display differential subcellular distributions with mu opioid receptor (MOPR) being mostly present on the plasma membrane and delta-opioid receptor (DOPR) and kappa-opioid receptor (KOPR) having a significant intracellular pool. Etorphine and DAMGO cause endocytosis of the MOPR, but morphine does not, except in some dendrites. Interestingly, chronic inflammatory pain and morphine treatment promote trafficking of intracellular DOPR to the cell surface which may account for the enhanced antinociceptive effects of DOPR agonists. KOPR has been reported to be associated with secretory vesicles in the posterior pituitary and translocated to the cell surface upon salt loading along with the release of vasopressin. The study of endogenous opioid receptors using in vivo models has produced some interesting results that could not have been anticipated in vitro. In vivo studies, therefore, are essential to provide insight into the mechanisms underlying opioid receptor regulation.
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Affiliation(s)
- Yulin Wang
- Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, 3420 North Broad Street, Philadelphia, PA 19140, USA
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 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 (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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