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Zhang W, Zhang Q, Liu Y, Pei J, Feng N. Novel roles of κ-opioid receptor in myocardial ischemia-reperfusion injury. PeerJ 2024; 12:e17333. [PMID: 38948204 PMCID: PMC11212630 DOI: 10.7717/peerj.17333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/12/2024] [Indexed: 07/02/2024] Open
Abstract
Acute heart attack is the primary cause of cardiovascular-related death worldwide. A common treatment is reperfusion of ischemic tissue, which can cause irreversible damage to the myocardium. The number of mitochondria in cardiomyocytes is large, which generate adenosine triphosphate (ATP) to sustain proper cardiac contractile function, and mitochondrial dysfunction plays a crucial role in cell death during myocardial ischemia-reperfusion, leading to an increasing number of studies investigating the impact of mitochondria on ischemia-reperfusion injury. The disarray of mitochondrial dynamics, excessive Ca2+ accumulation, activation of mitochondrial permeable transition pores, swelling of mitochondria, ultimately the death of cardiomyocyte are the consequences of ischemia-reperfusion injury. κ-opioid receptors can alleviate mitochondrial dysfunction, regulate mitochondrial dynamics, mitigate myocardial ischemia-reperfusion injury, exert protective effects on myocardium. The mechanism of κ-OR activation during myocardial ischemia-reperfusion to regulate mitochondrial dynamics and reduce myocardial ischemia-reperfusion injury will be discussed, so as to provide theoretical basis for the protection of ischemic myocardium.
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Affiliation(s)
- Wen Zhang
- Department of Physiology and Pathophysiology, Fouth Military Medical University, Xi’an, Shaanxi, China
- School of Life Science, Northwest University, Xi’an, Shaanxi, China
| | - Qi Zhang
- Graduate School, Dalian Medical University, Dalian, Liaoning, China
| | - Yali Liu
- Department of Physiology and Pathophysiology, Fouth Military Medical University, Xi’an, Shaanxi, China
| | - Jianming Pei
- Department of Physiology and Pathophysiology, Fouth Military Medical University, Xi’an, Shaanxi, China
| | - Na Feng
- Department of Physiology and Pathophysiology, Fouth Military Medical University, Xi’an, Shaanxi, China
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Cissom C, J Paris J, Shariat-Madar Z. Dynorphins in Development and Disease: Implications for Cardiovascular Disease. Curr Mol Med 2021; 20:259-274. [PMID: 31746302 DOI: 10.2174/1566524019666191028122559] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 12/12/2022]
Abstract
It is well-established that cardiovascular disease continues to represent a growing health problem and significant effort has been made to elucidate the underlying mechanisms. In this review, we report on past and recent high impact publications in the field of intracrine network signaling, focusing specifically on opioids and their interrelation with key modulators of the cardiovascular system and the onset of related disease. We present an overview of studies outlining the scope of cardiovascular and cerebrovascular processes that are affected by opioids, including heart function, ischemia, reperfusion, and blood flow. Specific emphasis is placed on the importance of dynorphin molecules in cerebrovascular and cardiovascular regulation. Evidence suggests that excessive or insufficient dynorphin could make an important contribution to cardiovascular physiology, yet numerous paradoxical observations frequently impede a clear understanding of the role of dynorphin. Thus, we argue that dynorphin-mediated signaling events for which an immediate regulatory effect is disputed should not be dismissed as unimportant, as they may play a role in cross-talk with other signaling networks. Finally, we consider the most recent evidence on the role of dynorphin during cardiovascular-related inflammation and on the potential value of endogenous and exogenous inhibitors of kappa-opioid receptor, a major dynorphin A receptor, to limit or prevent cardiovascular disease and its related sequelae.
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Affiliation(s)
- Cody Cissom
- William Carey College of Osteopathic Mississippi University, Medical School, Hattiesburg, Mississippi, United States
| | - Jason J Paris
- Department of Biomolecular Sciences, Division of Pharmacology, University of Mississippi, United States.,The National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, University of Mississippi, United States
| | - Zia Shariat-Madar
- Department of Biomolecular Sciences, Division of Pharmacology, University of Mississippi, United States.,The National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, University of Mississippi, United States.,Light Microscopy Core, University of Mississippi, University, Mississippi, United States
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3
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Beck TC, Hapstack MA, Beck KR, Dix TA. Therapeutic Potential of Kappa Opioid Agonists. Pharmaceuticals (Basel) 2019; 12:ph12020095. [PMID: 31226764 PMCID: PMC6631266 DOI: 10.3390/ph12020095] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/12/2019] [Accepted: 06/18/2019] [Indexed: 12/13/2022] Open
Abstract
Many original research articles have been published that describe findings and outline areas for the development of kappa-opioid agonists (KOAs) as novel drugs; however, a single review article that summarizes the broad potential for KOAs in drug development does not exist. It is well-established that KOAs demonstrate efficacy in pain attenuation; however, KOAs also have proven to be beneficial in treating a variety of novel but often overlapping conditions including cardiovascular disease, pruritus, nausea, inflammatory diseases, spinal anesthesia, stroke, hypoxic pulmonary hypertension, multiple sclerosis, addiction, and post-traumatic cartilage degeneration. This article summarizes key findings of KOAs and discusses the untapped therapeutic potential of KOAs in the treatment of many human diseases.
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Affiliation(s)
- Tyler C Beck
- Drug Discovery & Biomedical Sciences, Medical University of South Carolina, 280 Calhoun Street, QF204, Charleston, SC 29424-2303, USA.
- College of Medicine, 173 Ashley Ave., Charleston, SC 29424-2303, USA.
| | | | - Kyle R Beck
- College of Pharmacy, The Ohio State University, 500 W 12th Ave, Columbus, OH 43210-9998, USA.
| | - Thomas A Dix
- Drug Discovery & Biomedical Sciences, Medical University of South Carolina, 280 Calhoun Street, QF204, Charleston, SC 29424-2303, USA.
- JT Pharmaceuticals, Inc., 300 West Coleman Blvd., Suite 203, Mount Pleasant, SC 29464-2303, USA.
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4
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Theisen MM, Schlottmann S, August C, Herzog C, Theilmeier G, Maas M, Blumenstiel JM, Weber TP, Van Aken HK, Kaerlein KT. Detection and distribution of opioid peptide receptors in porcine myocardial tissue. Pharmacol Res 2014; 84:45-9. [PMID: 24788078 DOI: 10.1016/j.phrs.2014.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/12/2014] [Accepted: 04/20/2014] [Indexed: 12/16/2022]
Abstract
There is growing evidence that opioid peptide receptors (OPRs) play an important role in cardiovascular function. Many studies have been conducted in swine, in view of their anatomic and physiologic similarities to humans. Until now, the presence and particularly distribution of OPRs has been unclear. Porcine myocardial tissue was obtained from both the left and right atria and ventricles. Expression of mRNA for μ-, δ- and κ-OPR was determined by reverse transcription PCR. OPR proteins were detected by Western blot, distribution and cellular location were identified using immunohistochemistry. Homogenous expression of mRNA and protein for δ- and κ-OPRs were demonstrated in all porcine myocardial tissue tested, whereas expression of μ-OPR mRNA was not demonstrated in any of the tissues tested. This study demonstrates the expression of δ- and κ-OPRs in porcine myocardial tissue. No differences in distribution of δ- and κ-OPRs were found between the four heart cavities. Modulation of cardiac function by δ- and κ-OPR agonists or antagonists is therefore possible, while μ-OPR-mediated direct cardiac effects appear unlikely, due to nonexpression of the receptor. This study demonstrates that porcine studies can further elucidate the role of OPRs in cardiac (patho-)physiology.
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Affiliation(s)
- Marc Michael Theisen
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany; Department of Anesthesiology, Intensive Care and Pain Medicine, Raphaelsklinik Muenster, Loerstraße 23, D-48143 Muenster, Germany.
| | - Silke Schlottmann
- Department of Anesthesiology and Intensive Care, University of Ulm, Albert-Einstein-Allee 23, D-89081 Ulm, Germany
| | - Christian August
- Gerhard-Domagk-Institute of Pathology, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Christine Herzog
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Gregor Theilmeier
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Matthias Maas
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Jonas Martin Blumenstiel
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Thomas Peter Weber
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Hugo Karel Van Aken
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
| | - Kristoffer Tim Kaerlein
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany
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The effects of κ-opioid receptor on stretch-induced electrophysiological changes in infarcted rat hearts. Am J Med Sci 2013; 345:129-35. [PMID: 22735633 DOI: 10.1097/maj.0b013e31824ceba7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Kappa-opioid receptors (κ-OR) and mechanoelectric feedback seem to have common pathways that influence electrophysiological changes resulting from acute myocardial infarction (MI). This study aims to determine the effects of the κ-OR on stretch-induced electrophysiological changes after acute MI. METHODS Male Sprague-Dawley rats were randomly divided into 4 groups: sham operated, MI, U-50488H (a selective κ-OR agonist) -treated MI (MI+U-50488H) and nor-BNI (a selective κ-OR antagonist) -treated MI (MI+nor-BNI). After Langendorff perfusion to maintain stabilization, a transient stretch (5 seconds) was delivered early in diastole. Electrophysiological changes were recorded for 1 minute before and after stretch. Similarly, the 20%, 50% and 90% monophasic action potential duration (MAPD20, MAPD50 and MAPD90, respectively) and stretch-induced arrhythmias were recorded. RESULTS MAPD90 significantly increased in all 4 groups. MAPD90 in the MI and MI+nor-BNI groups increased significantly before stretch (P < 0.05) and after stretch (P < 0.01) but was reversed in the MI+U-50488H group (P > 0.05). MAPD90 in the MI group was increased compared with that of the MI+U-50488H group but decreased compared with that of the MI+ nor-BNI group after stretch (P < 0.01). The arrhythmia score in the MI and MI+nor-BNI groups was higher than that of the sham-operated group (P < 0.01), and the arrhythmia score in the MI+nor-BNI group was higher than that in MI group after stretch (P < 0.01). The arrhythmia score of the MI+U-50488H group was lower than that of MI group after stretch (P < 0.01). CONCLUSIONS The κ-OR could influence the stretch-induced electrophysiological changes and play an antiarrhythmic role in stretch-induced arrhythmias after acute MI.
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Hu LF, Li Y, Neo KL, Yong QC, Lee SW, Tan BKH, Bian JS. Hydrogen sulfide regulates Na+/H+ exchanger activity via stimulation of phosphoinositide 3-kinase/Akt and protein kinase G pathways. J Pharmacol Exp Ther 2011; 339:726-35. [PMID: 21865440 DOI: 10.1124/jpet.111.184754] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intracellular pH (pH(i)) is an important endogenous modulator of cardiac function. Inhibition of Na(+)/H(+) exchanger-1 (NHE-1) protects the heart by preventing Ca(2+) overload during ischemia/reperfusion. Hydrogen sulfide (H(2)S) has been reported to produce cardioprotection. The present study was designed to investigate the pH regulatory effect of H(2)S in rat cardiac myocytes and evaluate its contribution to cardioprotection. It was found that sodium hydrosulfide (NaHS), at a concentration range of 10 to 1000 μM, produced sustained decreases in pH(i) in the rat myocytes in a concentration-dependent manner. NaHS also abolished the intracellular alkalinization caused by trans-(±)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide methane-sulfonate hydrate (U50,488H), which activates NHEs. Moreover, when measured with an NHCl(4) prepulse method, NaHS was found to significantly suppress NHE-1 activity. Both NaHS and cariporide or [5-(2-methyl-5-fluorophenyl)furan-2-ylcarbonyl]guanidine (KR-32568), two NHE inhibitors, protected the myocytes against ischemia/reperfusion injury. However, coadministration of NaHS with KR-32568 did not produce any synergistic effect. Functional study showed that perfusion with NaHS significantly improved postischemic contractile function in isolated rat hearts subjected to ischemia/reperfusion. Blockade of phosphoinositide 3-kinase (PI3K) with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), Akt with Akt VIII, or protein kinase G (PKG) with (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]]enzodiazocine-10-carboxylic acid, methyl ester (KT5823) significantly attenuated NaHS-suppressed NHE-1 activity and/or NaHS-induced cardioprotection. Although KT5823 failed to affect NaHS-induced Akt phosphorylation, Akt inhibitor did attenuate NaHS-stimulated PKG activity. In conclusion, this work demonstrated for the first time that H(2)S produced cardioprotection via the suppression of NHE-1 activity involving a PI3K/Akt/PKG-dependent mechanism.
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Affiliation(s)
- Li-Fang Hu
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Antiarrhythmic effect mediated by κ-opioid receptor is associated with Cx43 stabilization*. Crit Care Med 2010; 38:2365-76. [DOI: 10.1097/ccm.0b013e3181fa0437] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Samways DSK, Henderson G. Opioid elevation of intracellular free calcium: possible mechanisms and physiological relevance. Cell Signal 2005; 18:151-61. [PMID: 16199136 DOI: 10.1016/j.cellsig.2005.08.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 08/19/2005] [Indexed: 01/02/2023]
Abstract
Opioid receptors are seven transmembrane domain Gi/G0 protein-coupled receptors, the activation of which stimulates a variety of intracellular signalling mechanisms including activation of inwardly rectifying potassium channels, and inhibition of both voltage-operated N-type Ca2+ channels and adenylyl cyclase activity. It is now apparent that like many other Gi/G0-coupled receptors, opioid receptor activation can significantly elevate intracellular free Ca2+ ([Ca2+]i), although the mechanism underlying this phenomenon is not well understood. In some cases opioid receptor activation alone appears to elevate [Ca2+]i, but in many cases it requires concomitant activation of Gq-coupled receptors, which themselves stimulate Ca2+ release from intracellular stores via the inositol phosphate pathway. Given the number of Ca2+-sensitive processes known to occur in cells, there are therefore a myriad of situations in which opioid receptor-mediated elevations of [Ca2+](i) may be important. Here, we review the literature documenting opioid receptor-mediated elevations of [Ca2+]i, discussing both the possible mechanisms underlying this phenomenon and its potential physiological relevance.
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Affiliation(s)
- Damien S K Samways
- Department of Pharmacological and Physiological Science, Health Science Center, School of Medicine, Saint Louis University, MO, USA.
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9
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Peart JN, Gross ER, Gross GJ. Effect of exogenous kappa-opioid receptor activation in rat model of myocardial infarction. J Cardiovasc Pharmacol 2004; 43:410-5. [PMID: 15076225 DOI: 10.1097/00005344-200403000-00012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The involvement of opioid receptor activation during ischemia-reperfusion is somewhat controversial. While it is generally accepted that activation of the delta-opioid receptor (DOR) is cardioprotective, and may indeed be an important mediator of ischemic preconditioning, the role of the kappa-opioid receptor (KOR) is less well understood. To this end, we examined three different KOR agonists and their effects upon infarct size and arrhythmia development. Male Sprague-Dawley rats were subjected to 30 minutes of occlusion followed by 90 minutes of reperfusion. Opioid receptor agonists were administered 10 minutes before the onset of ischemia, while the opioid antagonists were given 20 minutes before occlusion. Untreated rats exhibited an infarct size (IS/AAR%) of 52.4 +/- 2.7%. Pretreatment with the DOR agonist, BW373U86, limited infarct development to 37.2 +/- 1.8%, which was reversed by the selective DOR antagonist, BNTX. All three KOR agonists studied, U50,488, ICI 204,448, and BRL 52537 significantly reduced infarct size to levels comparable to that of BW373U86. The infarct-sparing effects of U50,488 and ICI 204,448 were abolished by the selective KOR antagonist, nor-BNI. Nor-BNI failed to inhibit the cardioprotective effects of BRL 52537. Furthermore, U50,488 and BRL 52537, but not ICI 204,448, significantly reduced the incidence of arrhythmias. These effects were not blocked by nor-BNI. These data demonstrate that KOR activation provides a similar degree of infarct size reduction as DOR activation. KOR agonists also reduced arrhythmogenesis; however, these responses appear to be independent of KOR activation.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/therapeutic use
- Animals
- Antihypertensive Agents/therapeutic use
- Arrhythmias, Cardiac/prevention & control
- Blood Pressure/drug effects
- Heart Rate/drug effects
- Male
- Myocardial Infarction/drug therapy
- Myocardial Infarction/therapy
- Myocardial Reperfusion
- Pyrrolidines/therapeutic use
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/physiology
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Affiliation(s)
- Jason N Peart
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53222, USA
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Coles JA, Sigg DC, Iaizzo PA. Role of kappa-opioid receptor activation in pharmacological preconditioning of swine. Am J Physiol Heart Circ Physiol 2003; 284:H2091-9. [PMID: 12543635 DOI: 10.1152/ajpheart.00843.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pharmacological preconditioning with kappa-opioid receptor agonists is proarrhythmic and exerts antipreconditioning effects in rats. In swine, it is unknown whether kappa-opioid receptor stimulation plays a role in pharmacological preconditioning. Swine were preconditioned with 1) saline (controls), 2) [d-Ala(2),d-Leu(5)]enkephalin (DADLE), 3) morphine, 4) pentazocine, 5) norbinaltorphimine (nor-BNI), 6) DADLE + nor-BNI, 7) morphine + nor-BNI, or 8) pentazocine + nor-BNI before occlusion (45 min) and reperfusion (180 min) of the left anterior descending coronary artery. Infarct size to area at risk (IS), regional (systolic shortening) and global (pressures and flows) myocardial function, and arrhythmia occurrence were assessed. Only DADLE + nor-BNI preconditioning significantly decreased infarct size compared with controls (47 +/- 13 vs. 65 +/- 5%, P < 0.05); morphine preconditioning was not cardioprotective with or without kappa-opioid receptor blockade (nor-BNI). DADLE preconditioning significantly increased ischemia-induced arrhythmias relative to controls, whereas pentazocine-preconditioned animals (n = 2) experienced intractable ventricular fibrillation during ischemia. kappa-Opioid receptor blockade with DADLE or pentazocine preconditioning alleviated proarrhythmic effects. These results suggest that kappa-opioid receptor activation during pharmacological preconditioning is proarrhythmic in swine.
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Affiliation(s)
- James A Coles
- Department of Surgery, University of Minnesota, Minneapolis 55455, USA
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Johnson-Davis KL, Hanson GR, Keefe KA. Lack of effect of kappa-opioid receptor agonism on long-term methamphetamine-induced neurotoxicity in rats. Neurotox Res 2003; 5:273-81. [PMID: 12835119 DOI: 10.1007/bf03033385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
High-dose methamphetamine treatment induces long-term deficits in central monoamine systems. However, the mechanisms underlying these effects are unknown. Previous work has shown that the Kappa-opioid receptor agonist U-69593 [(+)-(5alpha,7alpha,8b)-(+)-N-methyl-N[7-(1-pyrrolidinyl)-1-oxaspiro[4.5]dec-8-yl] benzeneacetamide] attenuates the neurotoxic effects of methamphetamine on extracellular dopamine levels in mice, suggesting that endogenous Kappa-opioid receptor ligands, such as dynorphin, may protect against methamphetamine-induced toxicity and play a role in mediating the long-term consequences of methamphetamine. To further examine the role that dynorphin systems play in methamphetamine-induced neurotoxicity, we administered to male rats a total of four injections of methamphetamine (7.5 mg/kg, s.c.), with a 2-h interval between each dose. Rats were pretreated with either the Kappa-agonist U-69593 (0.32 mg/kg, s.c.) or vehicle, 15 min prior to the first and third methamphetamine injection. Furthermore, cages containing the U-69593 + methamphetamine-treated rats were placed on heating pads for 30 min after the first U-69593 injection to prevent the drug from blocking methamphetamine-induced hyperthermia. Rats were sacrificed 7 days after treatment. Striatal dopamine and serotonin contents were decreased approximately 75% and 55%, respectively, in the methamphetamine-treated rats and approximately 88% and 65%, respectively, in rats receiving the U-69593 + methamphetamine combination. There was a approximately 20% mortality rate in the rats treated with methamphetamine compared to approximately 75% mortality rate in rats treated with both U-69593 and methamphetamine. A similar rate of mortality was observed when combining a different Kappa-agonist, U-50488 [trans-(-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamine], with methamphetamine. These data suggest that Kappa-agonists do not protect against methamphetamine-induced toxicity to monoamines in rats, and may potentiate mortality when co-administered with methamphetamine.
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Affiliation(s)
- Kamisha L Johnson-Davis
- Department of Pharmacology and Toxicology, University of Utah, 30 South 2000 East, Rm. 201, Salt Lake City, UT 84112, USA.
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