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Gledhill LJ, Babey AM. Synthesis of the Mechanisms of Opioid Tolerance: Do We Still Say NO? Cell Mol Neurobiol 2021; 41:927-948. [PMID: 33704603 DOI: 10.1007/s10571-021-01065-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/12/2021] [Indexed: 10/21/2022]
Abstract
The use of morphine as a first-line agent for moderate-to-severe pain is limited by the development of analgesic tolerance. Initially opioid receptor desensitization in response to repeated stimulation, thought to underpin the establishment of tolerance, was linked to a compensatory increase in adenylate cyclase responsiveness. The subsequent demonstration of cross-talk between N-methyl-D-aspartate (NMDA) glutamate receptors and opioid receptors led to the recognition of a role for nitric oxide (NO), wherein blockade of NO synthesis could prevent tolerance developing. Investigations of the link between NO levels and opioid receptor desensitization implicated a number of events including kinase recruitment and peroxynitrite-mediated protein regulation. Recent experimental advances and the identification of new cellular constituents have expanded the potential signaling candidates to include unexpected, intermediary compounds not previously linked to this process such as zinc, histidine triad nucleotide-binding protein 1 (HINT1), micro-ribonucleic acid (mi-RNA) and regulator of G protein signaling Z (RGSZ). A further complication is a lack of consistency in the protocols used to create tolerance, with some using acute methods measured in minutes to hours and others using days. There is also an emphasis on the cellular changes that are extant only after tolerance has been established. Although a review of the literature demonstrates a lack of spatio-temporal detail, there still appears to be a pivotal role for nitric oxide, as well as both intracellular and intercellular cross-talk. The use of more consistent approaches to verify these underlying mechanism(s) could provide an avenue for targeted drug development to rescue opioid efficacy.
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Affiliation(s)
- Laura J Gledhill
- CURA Pharmacy, St. John of God Hospital, Bendigo, VIC, 3550, Australia
| | - Anna-Marie Babey
- Faculty of Medicine and Health, University of New England, Armidale, NSW, 2351, Australia.
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Blackwood CA, McCoy MT, Ladenheim B, Cadet JL. Oxycodone self-administration activates the mitogen-activated protein kinase/ mitogen- and stress-activated protein kinase (MAPK-MSK) signaling pathway in the rat dorsal striatum. Sci Rep 2021; 11:2567. [PMID: 33510349 PMCID: PMC7843984 DOI: 10.1038/s41598-021-82206-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 01/12/2021] [Indexed: 01/23/2023] Open
Abstract
To identify signaling pathways activated by oxycodone self-administration (SA), Sprague–Dawley rats self-administered oxycodone for 20 days using short—(ShA, 3 h) and long-access (LgA, 9 h) paradigms. Animals were euthanized 2 h after SA cessation and dorsal striata were used in post-mortem molecular analyses. LgA rats escalated their oxycodone intake and separated into lower (LgA-L) or higher (LgA-H) oxycodone takers. LgA-H rats showed increased striatal protein phosphorylation of ERK1/2 and MSK1/2. Histone H3, phosphorylated at serine 10 and acetylated at lysine 14 (H3S10pK14Ac), a MSK1/2 target, showed increased abundance only in LgA-H rats. RT-qPCR analyses revealed increased AMPA receptor subunits, GluA2 and GluA3 mRNAs, in the LgA-H rats. GluA3, but not GluA2, mRNA expression correlated positively with changes in pMSK1/2 and H3S10pK14Ac. These findings suggest that escalated oxycodone SA results in MSK1/2-dependent histone phosphorylation and increases in striatal gene expression. These observations offer potential avenues for interventions against oxycodone addiction.
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Affiliation(s)
- Christopher A Blackwood
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Michael T McCoy
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Bruce Ladenheim
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Jean Lud Cadet
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD, 21224, USA.
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Chronic activation of Mas-related gene receptors (Mrg) reduces the potency of morphine-induced analgesia via PKC pathway in naive rats. Brain Res 2019; 1722:146363. [PMID: 31394092 DOI: 10.1016/j.brainres.2019.146363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 07/09/2019] [Accepted: 08/03/2019] [Indexed: 01/27/2023]
Abstract
Mas oncogene-related gene receptors (Mrg) are uniquely distributed in small and medium cells of trigeminal and dorsal root ganglia (DRG). The physiological and pharmacological properties of Mrg are unknown. We have shown that intermittent activation of MrgC prevents and reverses morphine tolerance. Now we observed that intrathecal (i.t.) administration of the MrgC agonist bovine adrenal medulla 8-22 (BAM8-22, 3 nmol) for 3 and 6 days reduced the potency of morphine analgesia by 1.5 and 3.5 folds, respectively. Daily administration of BAM8-22 for 6 days also significantly decreased the tail flick latency. The administration of another MrgC agonist (Tyr6)-γ2-MSH-6-12 (MSH, 3 nmol) reduced morphine potency and the reduction was abolished following the co-administration of the protein kinase C (PKC) inhibitor chelerythrine chloride (CLT, 3 nmol). The chronic treatment with BAM8-22 or MSH increased the expression of PKC-gamma (PKCγ) in the cell membrane of spinal dorsal horn neurons and PKC-epsilon (PKCε) in the cell membrane and cytosol of DRG neurons. Moreover, the BAM8-22 treatment induced an increase in the expression of calcitonin gene-related peptide (CGRP) and neuronal nitric oxide synthase (nNOS) in small and medium cells in DRG. All of these responses were not seen when BAM8-22 or MSH was co-administered with the PKC inhibitor CLT (3 nmol) or GF-109203X (10 nmol). The present study suggested that the chronic activation of MrgC upregulated expressions of pronociceptive mediators via PKC signaling pathway leading to the suppression of antinociceptive property of morphine. These effects are opposite to those occurred when MrgC is activated acutely or moderately.
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B Vitamins Potentiate Acute Morphine Antinociception and Attenuate the Development of Tolerance to Chronic Morphine in Mice. PAIN MEDICINE 2017; 18:1961-1974. [DOI: 10.1093/pm/pnw358] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bian JM, Wu N, Su RB, Li J. Phosphatidylethanolamine-binding protein is not involved in µ-opioid receptor-mediated regulation of extracellular signal-regulated kinase. Mol Med Rep 2015; 11:3368-74. [PMID: 25573435 PMCID: PMC4368089 DOI: 10.3892/mmr.2015.3161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 11/25/2014] [Indexed: 12/18/2022] Open
Abstract
Stimulation of the µ‑opioid receptor activates extracellular signal‑regulated kinase (ERK), however, the mechanism by which this occurs remains to be elucidated. Phosphatidylethanolamine‑binding protein (PEBP) has been reported to act as a negative regulator of the ERK cascade (Raf‑MEK‑ERK) by binding to Raf‑1 kinase. In the present study, the role of PEBP in µ‑opioid receptor‑mediated ERK activation was investigated in Chinese hamster ovary/µ cells and SH‑SY5Y cells, as well as in human embryonic kidney 293 cells expressing other types of G protein‑coupled receptors. The acute activation of µ‑opioid receptors by morphine or (D‑Ala2, MePhe4, Gly5‑ol) enkephalin induced a rapid activation of ERK. Prolonged morphine treatment did not affect the phosphorylation level of ERK compared with control cells, but the phosphorylation level of ERK decreased markedly when cells were precipitated with naloxone following chronic morphine treatment. For the phosphorylation of PEBP, no change was identified under the designated drug treatment and exposure duration. A total of two other types of G protein‑coupled receptors, including Gs‑coupled dopamine D1 receptors and Gq‑coupled adrenergic α1A receptors were also investigated and only the activation of adrenergic α1A receptors induced an upregulated phosphorylation of PEBP, which was protein kinase C activity dependent. Thus, PEBP did not have a significant role in µ‑opioid receptor‑mediated regulation of ERK.
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Affiliation(s)
- Jia-Ming Bian
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, P.R. China
| | - Ning Wu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, P.R. China
| | - Rui-Bin Su
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, P.R. China
| | - Jin Li
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, P.R. China
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Wollemann M, Tóth F, Benyhe S. Protein kinase C inhibitor BIM suspended TRPV1 effect on mu-opioid receptor. Brain Res Bull 2013; 90:114-7. [DOI: 10.1016/j.brainresbull.2012.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/03/2012] [Indexed: 12/12/2022]
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Zhao YL, Chen SR, Chen H, Pan HL. Chronic opioid potentiates presynaptic but impairs postsynaptic N-methyl-D-aspartic acid receptor activity in spinal cords: implications for opioid hyperalgesia and tolerance. J Biol Chem 2012; 287:25073-85. [PMID: 22679016 DOI: 10.1074/jbc.m112.378737] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Opioids are the most effective analgesics for the treatment of moderate to severe pain. However, chronic opioid treatment can cause both hyperalgesia and analgesic tolerance, which limit their clinical efficacy. In this study, we determined the role of pre- and postsynaptic NMDA receptors (NMDARs) in controlling increased glutamatergic input in the spinal cord induced by chronic systemic morphine administration. Whole-cell voltage clamp recordings of excitatory postsynaptic currents (EPSCs) were performed on dorsal horn neurons in rat spinal cord slices. Chronic morphine significantly increased the amplitude of monosynaptic EPSCs evoked from the dorsal root and the frequency of spontaneous EPSCs, and these changes were largely attenuated by blocking NMDARs and by inhibiting PKC, but not PKA. Also, blocking NR2A- or NR2B-containing NMDARs significantly reduced the frequency of spontaneous EPSCs and the amplitude of evoked EPSCs in morphine-treated rats. Strikingly, morphine treatment largely decreased the amplitude of evoked NMDAR-EPSCs and NMDAR currents of dorsal horn neurons elicited by puff NMDA application. The reduction in postsynaptic NMDAR currents caused by morphine was prevented by resiniferatoxin pretreatment to ablate TRPV1-expressing primary afferents. Furthermore, intrathecal injection of the NMDAR antagonist significantly attenuated the development of analgesic tolerance and the reduction in nociceptive thresholds induced by chronic morphine. Collectively, our findings indicate that chronic opioid treatment potentiates presynaptic, but impairs postsynaptic, NMDAR activity in the spinal cord. PKC-mediated increases in NMDAR activity at nociceptive primary afferent terminals in the spinal cord contribute critically to the development of opioid hyperalgesia and analgesic tolerance.
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Affiliation(s)
- Yi-Lin Zhao
- Center for Pain and Neuroscience Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
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Aira Z, Buesa I, Del Caño GG, Salgueiro M, Mendiable N, Mingo J, Aguilera L, Bilbao J, Azkue JJ. Selective impairment of spinal mu-opioid receptor mechanism by plasticity of serotonergic facilitation mediated by 5-HT2A and 5-HT2B receptors. Pain 2012; 153:1418-1425. [PMID: 22520172 DOI: 10.1016/j.pain.2012.03.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/19/2012] [Accepted: 03/14/2012] [Indexed: 01/11/2023]
Abstract
Opioid analgesia is compromised by intracellular mediators such as protein kinase C (PKC). The phosphatidylinositol hydrolysis-coupled serotonin receptor 5-HT2 is ideally suited to promote PKC activation. We test the hypothesis that 5-HT2A and 5-HT2B receptors, which have been previously shown to become pro-excitatory after spinal nerve ligation (SNL), can negatively influence the ability of opioids to depress spinal excitation evoked by noxious input. Spinal superfusion with (100 nM) mu-opioid receptor (MOR)-agonist DAMGO significantly depressed C fiber-evoked spinal field potentials. Simultaneous administration of subclinical 5-HT2AR antagonist 4F 4PP (100 nM) or 5-HT2BR antagonist SB 204741 (100 nM) significantly reduced the IC50 value for DAMGO in nerve-ligated rats (97.56 nM ± 1.51 and 1.20 nM ± 1.28 respectively, relative to 104 nM ± 1.08 at the baseline condition), but not in sham-operated rats. Both antagonists failed to alter depression induced by delta-opioid receptor (DOR)-agonist D-ala2-deltorphin II after SNL as well as in the sham condition. Western blot analysis of dorsal horn homogenates revealed bilateral upregulation of 5-HT2AR and 5-HT2BR protein band densities after SNL. As assessed from double immunofluorescence labeling for confocal laser scanning microscopy, scarce dorsal horn cell processes showed co-localization color overlay for 5-HT2AR/MOR, 5-HT2BR/MOR, 5-HT2AR/DOR, or 5-HT2BR/DOR in sham-operated rats. Intensity correlation-based analyses showed significant increases in 5-HT2AR/MOR and 5-HT2BR/MOR co-localizations after SNL. These results indicate that plasticity of spinal serotonergic neurotransmission can selectively reduce spinal MOR mechanisms via 5-HT2A and 5-HT2B receptors, including upregulation of the latter and increased expression in dorsal horn neurons containing MOR.
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Affiliation(s)
- Zigor Aira
- Department of Neurosciences, School of Medicine and Dentistry, University of the Basque Country, Leioa, Spain Department of Neurosciences, School of Pharmacy, University of the Basque Country, Vitoria-Gasteiz, Spain Department of Surgery, Radiology and Physical Medicine, University of the Basque Country, Bilbao, Spain Department of Preventive Medicine and Public Health, School of Medicine and Dentistry, University of the Basque Country, Leioa, Spain
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Martín F, Mora L, Laorden M, Milanés M. Protein kinase C phosphorylates the cAMP response element binding protein in the hypothalamic paraventricular nucleus during morphine withdrawal. Br J Pharmacol 2011; 163:857-75. [PMID: 21615389 DOI: 10.1111/j.1476-5381.2011.01287.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Exposure to drugs of abuse or stress results in adaptation in the brain involving changes in gene expression and transcription factors. Morphine withdrawal modulates gene expression through various second-messenger signal transduction systems. Here, we investigated changes in activation of the transcription factor, cAMP-response element binding protein (CREB), in the hypothalamic paraventricular nucleus (PVN) and the kinases that may mediate the morphine withdrawal-triggered activation of CREB and the response of the hypothalamic-pituitary-adrenocortical (HPA) axis after naloxone-induced morphine withdrawal. EXPERIMENTAL APPROACH The effects of morphine dependence and withdrawal, phosphorylated CREB (pCREB), corticotrophin-releasing factor (CRF) expression in the PVN and HPA axis activity were measured using immunoblotting, immunohistochemistry and radioimmunoassay in controls and in morphine-dependent rats, withdrawn with naloxone and pretreated with vehicle, calphostin C, chelerythrine (inhibitors of protein kinase C (PKC) or SL-327 [inhibitor of extracellular signal regulated kinase (ERK) kinase]. In addition, changes in PKCα and PKCγ immunoreactivity were measured after 60 min of withdrawal. KEY RESULTS In morphine-withdrawn rats, pCREB immunoreactivity was increased within CRF immunoreactive neurons in the PVN and plasma corticosterone levels were raised. SL-327, at doses that reduced the augmented pERK levels in the PVN, did not attenuate the rise in pCREB immunoreactivity or plasma corticosterone secretion. In contrast, PKC inhibition reduced the withdrawal-triggered rise in pCREB, pERK1/2 and corticosterone secretion. CONCLUSIONS AND IMPLICATIONS PKC mediated, in part, both CREB activation and the HPA response to morphine withdrawal. The ERK kinase/ERK pathway might not be necessary for either activation of CREB or HPA axis hyperactivity.
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Affiliation(s)
- F Martín
- Group of Cellular and Molecular Pharmacology, Department of Pharmacology, University School of Medicine, Murcia, Spain
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10
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Opioid Receptor Trafficking and Signaling: What Happens After Opioid Receptor Activation? Cell Mol Neurobiol 2011; 32:167-84. [DOI: 10.1007/s10571-011-9755-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/04/2011] [Indexed: 01/14/2023]
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Raehal KM, Schmid CL, Groer CE, Bohn LM. Functional selectivity at the μ-opioid receptor: implications for understanding opioid analgesia and tolerance. Pharmacol Rev 2011; 63:1001-19. [PMID: 21873412 DOI: 10.1124/pr.111.004598] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Opioids are the most effective analgesic drugs for the management of moderate or severe pain, yet their clinical use is often limited because of the onset of adverse side effects. Drugs in this class produce most of their physiological effects through activation of the μ opioid receptor; however, an increasing number of studies demonstrate that different opioids, while presumably acting at this single receptor, can activate distinct downstream responses, a phenomenon termed functional selectivity. Functional selectivity of receptor-mediated events can manifest as a function of the drug used, the cellular or neuronal environment examined, or the signaling or behavioral measure recorded. This review summarizes both in vitro and in vivo work demonstrating functional selectivity at the μ opioid receptor in terms of G protein coupling, receptor phosphorylation, interactions with β-arrestins, receptor desensitization, internalization and signaling, and details on how these differences may relate to the progression of analgesic tolerance after their extended use.
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Affiliation(s)
- Kirsten M Raehal
- Molecular Therapeutics and Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
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12
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Feng B, Li Z, Wang JB. Protein kinase C-mediated phosphorylation of the μ-opioid receptor and its effects on receptor signaling. Mol Pharmacol 2011; 79:768-75. [PMID: 21212139 DOI: 10.1124/mol.110.069096] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phosphorylation of the μ opioid receptor (MOPr), mediated by several protein kinases, is a critical process in the regulation of MOPr signaling. Although G protein-coupled receptor kinases are known to play an essential role in the agonist-induced phosphorylation and desensitization of MOPr, evidence suggests that other protein kinases, especially protein kinase C (PKC), also participate in the regulation of MOPr signaling. In this study, we investigated the biochemical nature and downstream effects of PKC-mediated MOPr phosphorylation. We observed in vitro phosphorylation of the MOPr C terminus by purified PKC. Protein mass spectrometry and site-directed mutagenesis implicated Ser363 of MOPr as the primary substrate for PKC, and this was confirmed in Chinese hamster ovary cells stably expressing full-length MOPr using an antibody that specifically recognizes phosphorylated Ser363. Alanine mutation of Ser363 did not affect the affinity of MOPr-ligand binding and the efficiency of receptor G-protein coupling. However, the S363A mutation attenuated the desensitization of receptor G-protein coupling induced by phorbol 12-myristate. Our research thus has identified a specific PKC phosphorylation site in MOPr and demonstrated that PKC-mediated phosphorylation of MOPr induces receptor desensitization at the G protein coupling level.
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Affiliation(s)
- Bo Feng
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
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Is slow-onset long-acting monoamine transport blockade to cocaine as methadone is to heroin? Implication for anti-addiction medications. Neuropsychopharmacology 2010; 35:2564-78. [PMID: 20827272 PMCID: PMC2978747 DOI: 10.1038/npp.2010.133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The success of methadone in treating opiate addiction has suggested that long-acting agonist therapies may be similarly useful for treating cocaine addiction. Here, we examined this hypothesis, using the slow-onset long-acting monoamine reuptake inhibitor 31,345, a trans-aminotetralin analog, in a variety of addiction-related animal models, and compared it with methadone's effects on heroin's actions in the same animal models. Systemic administration of 31,345 produced long-lasting enhancement of electrical brain-stimulation reward (BSR) and extracellular nucleus accumbens (NAc) dopamine (DA). Pretreatment with 31,345 augmented cocaine-enhanced BSR, prolonged cocaine-enhanced NAc DA, and produced a long-term (24-48 h) reduction in cocaine self-administration rate without obvious extinction pattern, suggesting an additive effect of 31,345 with cocaine. In contrast, methadone pretreatment not only dose-dependently inhibited heroin self-administration with an extinction pattern but also dose-dependently inhibited heroin-enhanced BSR and NAc DA, suggesting functional antagonism by methadone of heroin's actions. In addition, 31,345 appears to possess significant abuse liability, as it produces dose-dependent enhancement of BSR and NAc DA, maintains a low rate of self-administration behavior, and dose-dependently reinstates drug-seeking behavior. In contrast, methadone only partially maintains self-administration with an extinction pattern, and fails to induce reinstatement of drug-seeking behavior. These findings suggest that 31,345 is a cocaine-like slow-onset long-acting monoamine transporter inhibitor that may act as an agonist therapy for cocaine addiction. However, its pattern of action appears to be significantly different from that of methadone. Ideal agonist substitutes for cocaine should fully emulate methadone's actions, that is, functionally antagonizing cocaine's action while blocking monoamine transporters to augment synaptic DA.
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Yin H, Lee KE, Park SA, Bhattarai JP, Suh BJ, Jeon JG, Kim BG, Park SJ, Han SK. Inhibitory effects of somatostatin on the substantia gelatinosa neurons of trigeminal subnucleus caudalis via somatostatin type 2 receptors in juvenile mice. Brain Res 2009; 1304:49-56. [DOI: 10.1016/j.brainres.2009.09.070] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 09/09/2009] [Accepted: 09/17/2009] [Indexed: 11/16/2022]
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Bedini A, Baiula M, Carbonari G, Spampinato S. Transcription factor REST negatively influences the protein kinase C-dependent up-regulation of human mu-opioid receptor gene transcription. Neurochem Int 2009; 56:308-17. [PMID: 19913583 DOI: 10.1016/j.neuint.2009.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/20/2009] [Accepted: 10/29/2009] [Indexed: 11/15/2022]
Abstract
Mu-opioid receptor expression increases during neurogenesis, regulates the survival of maturing neurons and is implicated in ischemia-induced neuronal death. The repressor element 1 silencing transcription factor (REST), a regulator of a subset of genes in differentiating and post-mitotic neurons, is involved in its transcriptional repression. Extracellular signaling molecules and mechanisms that control the human mu-opioid receptor (hMOR) gene transcription are not clearly understood. We examined the role of protein kinase C (PKC) on hMOR transcription in a model of neuronal cells and in the context of the potential influence of REST. In native SH-SY5Y neuroblastoma cells, PKC activation with phorbol 12-myristate 13-acetate (PMA, 16 nM, 24h) down-regulated hMOR transcription and concomitantly elevated the REST binding activity to repressor element 1 of the hMOR promoter. In contrast, PMA activated hMOR gene transcription when REST expression was knocked down by an antisense strategy or by retinoic acid-induced cell differentiation. PMA acts through a PKC-dependent pathway requiring downstream MAP kinases and the transcription factor AP-1. In a series of hMOR-luciferase promoter/reporter constructs transfected into SH-SY5Y cells and PC12 cells, PMA up-regulated hMOR transcription in PC12 cells lacking REST, and in SH-SY5Y cells either transfected with constructs deficient in the REST DNA binding element or when REST was down-regulated in retinoic acid-differentiated cells. These findings help explain how hMOR transcription is regulated and may clarify its contribution to epigenetic modifications and reprogramming of differentiated neuronal cells exposed to PKC-activating agents.
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Affiliation(s)
- Andrea Bedini
- Department of Pharmacology, University of Bologna, Bologna, Italy
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Wollemann M, Ioja E, Benyhe S. Capsaicin inhibits the in vitro binding of peptides selective for mu- and kappa-opioid, and nociceptin-receptors. Brain Res Bull 2008; 77:136-42. [PMID: 18588953 DOI: 10.1016/j.brainresbull.2008.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 06/03/2008] [Accepted: 06/03/2008] [Indexed: 10/21/2022]
Abstract
Capsaicin inhibited the equilibrium specific binding of endogenous opioid-like peptide ligands such as endomorphin-1, nociceptin, and dynorphin((1-17)) in rat brain membrane preparations. We studied the in vitro effect of capsaicin (1-10 microM) on homologous and heterologous competitive binding of opioid ligands, using unlabeled synthetic peptides and the following tritiated compounds: [(3)H]endomorphin-1, [(3)H]endomorphin-2, [(3)H]nociceptin((1-17)) and [(3)H]dynorphin((1-17)). Capsaicin-dependent inhibition was also observed in [(35)S]GTPgammaS stimulation assays in the presence of certain opioid peptides. The inhibition of opioid binding was further investigated using other synthetic and natural mu-opioid ligands such as [D-Ala(2),(NMe)Phe(4),Gly(5)-ol]enkephalin (DAMGO), morphine and naloxone. The decrease in opioid ligand affinity upon capsaicin treatments was most apparent with endomorphin-1, followed by nociceptin and dynorphin. The binding of other investigated opioids were not affected in the presence of capsaicin. In [(3)H]endomorphin-1 binding assays, capsazepine antagonized the inhibitory effect of capsaicin in rat brain membranes suggesting the involvement of TRPV1 receptors. In Chinese hamster ovary (CHO) cells stably expressing mu-opioid receptors, but lacking vanilloid receptors, the inhibition by capsaicin on the binding of [(3)H]endomorphin-1 was not present. It is concluded that the inhibitory effect of capsaicin on the receptor binding affinity of endogenous opioid peptides in brain membrane preparations seems not to be a direct effect, it is rather a negative feedback interaction with opioid receptors.
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Affiliation(s)
- Mária Wollemann
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, H-6726 Szeged, Temesvari krt. 26, Hungary.
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Bailey CP, Smith FL, Kelly E, Dewey WL, Henderson G. How important is protein kinase C in μ-opioid receptor desensitization and morphine tolerance? Trends Pharmacol Sci 2006; 27:558-65. [PMID: 17000011 DOI: 10.1016/j.tips.2006.09.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 08/21/2006] [Accepted: 09/12/2006] [Indexed: 11/30/2022]
Abstract
The repeated administration of opiate drugs such as morphine results in the development of tolerance to their analgesic, rewarding (euphoric) and respiratory-depressant effects; thus, to obtain the same level of response with subsequent administrations, a greater dose must be used. Tolerance can limit the clinical efficacy of opiate drugs and enhance the social problems that are inherent in recreational opioid abuse. Surprisingly, the mechanism (or mechanisms) underlying the development of morphine tolerance remains controversial. Here, we propose that protein kinase C could have a crucial role in the desensitization of mu-opioid receptors by morphine and that this cellular process could contribute to the development and maintenance of morphine tolerance in vivo.
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Affiliation(s)
- Chris P Bailey
- Department of Pharmacology, University of Bristol, Bristol BS8 1TD, UK
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18
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Wang ZJ, Wang LX. Phosphorylation: A molecular switch in opioid tolerance. Life Sci 2006; 79:1681-91. [PMID: 16831450 DOI: 10.1016/j.lfs.2006.05.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 04/26/2006] [Accepted: 05/24/2006] [Indexed: 02/07/2023]
Abstract
Protein phosphorylation is a key posttranslational modification mechanism controlling the conformation and activity of many proteins. Increasing evidence has implicated an essential role of phosphorylation by several major protein kinases in promoting and maintaining opioid tolerance. We review some of the most recent studies on protein kinase C (PKC), cyclic AMP dependent protein kinase A (PKA), calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase G (PKG), and G protein receptor kinase (GRK). These kinases act as the molecular switches to modulate opioid tolerance. Pharmacological interventions at one or more of the protein kinases and phosphatases may provide valuable strategies to improve opioid analgesia by attenuating tolerance to these drugs.
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Affiliation(s)
- Zaijie Jim Wang
- Department of Biopharmaceutical Sciences and Cancer Center, University of Illinois, Chicago, IL 60612, USA.
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19
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Johnson EA, Oldfield S, Braksator E, Gonzalez-Cuello A, Couch D, Hall KJ, Mundell SJ, Bailey CP, Kelly E, Henderson G. Agonist-Selective Mechanisms of μ-Opioid Receptor Desensitization in Human Embryonic Kidney 293 Cells. Mol Pharmacol 2006; 70:676-85. [PMID: 16682505 DOI: 10.1124/mol.106.022376] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability of two opioid agonists, [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) and morphine, to induce mu-opioid receptor (MOR) phosphorylation, desensitization, and internalization was examined in human embryonic kidney (HEK) 293 cells expressing rat MOR1 as well G protein-coupled inwardly rectifying potassium channel (GIRK) channel subunits. Both DAMGO and morphine activated GIRK currents, but the maximum response to DAMGO was greater than that of morphine, indicating that morphine is a partial agonist. The responses to DAMGO and morphine desensitized rapidly in the presence of either drug. Expression of a dominant negative mutant G protein-coupled receptor kinase 2 (GRK2), GRK2-K220R, markedly attenuated the DAMGO-induced desensitization of MOR1, but it had no effect on morphine-induced MOR1 desensitization. In contrast, inhibition of protein kinase C (PKC) either by the PKC inhibitory peptide PKC (19-31) or staurosporine reduced MOR1 desensitization by morphine but not that induced by DAMGO. Morphine and DAMGO enhanced MOR1 phosphorylation over basal. The PKC inhibitor bisindolylmaleimide 1 (GF109203X) inhibited MOR1 phosphorylation under basal conditions and in the presence of morphine, but it did not inhibit DAMGO-induced phosphorylation. DAMGO induced arrestin-2 translocation to the plasma membrane and considerable MOR1 internalization, whereas morphine did not induce arrestin-2 translocation and induced very little MOR1 internalization. Thus, DAMGO and morphine each induce desensitization of MOR1 signaling in HEK293 cells but by different molecular mechanisms; DAMGO-induced desensitization is GRK2-dependent, whereas morphine-induced desensitization is in part PKC-dependent. MORs desensitized by DAMGO activation are then readily internalized by an arrestin-dependent mechanism, whereas those desensitized by morphine are not. These data suggest that opioid agonists induce different conformations of the MOR that are susceptible to different desensitizing and internalization processes.
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20
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Schallmach E, Steiner D, Vogel Z. Adenylyl cyclase type II activity is regulated by two different mechanisms: implications for acute and chronic opioid exposure. Neuropharmacology 2006; 50:998-1005. [PMID: 16545401 DOI: 10.1016/j.neuropharm.2006.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Revised: 01/02/2006] [Accepted: 01/25/2006] [Indexed: 11/16/2022]
Abstract
Acute and chronic activation of opioid receptors differentially regulate the activity of the various adenylyl cyclase (AC) isoforms. In several AC isoforms (I, V, VI and VIII) acute opioid activation (by agonists such as morphine) leads to AC inhibition, while prolonged opioid activation leads to increase in AC activity, a phenomenon known as AC sensitization or superactivation. In several other AC isoforms (II, IV and VII), acute opioid activation leads to AC stimulation, while chronic opioid exposure inhibits AC activity, in a process, which in analogy to the term "superactivation" is referred to as "superinhibition". AC-II is highly regulated by multiple and independent biochemical stimuli, including Gbetagamma, Galphas and PKC activation. We investigated the regulation of AC-II by Galphas and by PKC under conditions of acute and chronic exposure to opioid agonists in COS-7 transfected cells. We found that acute opioid exposure led to an increase in AC-II activity by either Galphas or PKC stimulation. This effect seems to be regulated by Gbetagamma subunits, in both activation pathways, as the increase in AC-II activity was abolished by pertussis toxin treatment and by Gbetagamma scavengers. On the other hand, while chronic opioid exposure led to a decrease in AC-II activity ("superinhibition") upon stimulation of the Galphas pathway, this superinhibition was not observed when the opioid treated cells were stimulated via PKC activation.
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Affiliation(s)
- Ester Schallmach
- Department of Neurobiology, The Weizmann Institute of Science, Hertzel str, Rehovot 76100, Israel
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21
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Almela P, Cerezo M, Milanés MV, Laorden ML. Role of PKC in regulation of Fos and TH expression after naloxone induced morphine withdrawal in the heart. Naunyn Schmiedebergs Arch Pharmacol 2006; 372:374-82. [PMID: 16474935 DOI: 10.1007/s00210-006-0032-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 12/19/2005] [Indexed: 11/29/2022]
Abstract
We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. The present study was designed to investigate the role of protein kinase C (PKC) in this process, by estimating whether pharmacological inhibition of PKC would attenuate morphine withdrawal induced Fos expression and changes in tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced on day 8 by an injection of naloxone. Morphine withdrawal induced Fos expression and increased TH levels and NA turnover in the right and left ventricle. Infusion of calphostin C, a selective PKC inhibitor, did not modify the morphine withdrawal-induced increase in NA turnover and TH levels. However, this inhibitor produced a reduction in the morphine withdrawal-induced Fos expression. The results of the present study provide new information on the mechanisms that underlie morphine withdrawal-induced up-regulation of Fos expression in the heart and suggest that TH is not a target of PKC during morphine withdrawal at heart levels.
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Affiliation(s)
- Pilar Almela
- Equip of Cellular and Molecular Pharmacology, University School of Medicine, Murcia, Spain
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22
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Cerezo M, Milanés MV, Laorden ML. Alterations in protein kinase A and different protein kinase C isoforms in the heart during morphine withdrawal. Eur J Pharmacol 2005; 522:9-19. [PMID: 16202991 DOI: 10.1016/j.ejphar.2005.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 07/21/2005] [Accepted: 08/15/2005] [Indexed: 10/25/2022]
Abstract
The present study was designed to investigate the possible changes of protein kinase A (PKA) and different isoforms of protein kinase C (PKC): PKC alpha, PKC delta and PKC zeta after naloxone induced morphine withdrawal in the heart. Male rats were implanted with placebo (naïve) or morphine (tolerant/dependent) pellets for 7 days. On day 8 rats received saline s.c. or naloxone (5 mg/kg s.c.). The protein levels of PKA, PKC delta and PKC zeta were significantly up-regulated in the heart from morphine withdrawal rats. By contrast, morphine withdrawal induced down-regulation of PKC alpha. These results suggest that both PKA and PKC may be involved in the cardiac adaptive changes observed during morphine withdrawal.
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Affiliation(s)
- Manuela Cerezo
- Equip of Cellular and Molecular Pharmacology, University School of Medicine, Murcia, Spain
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23
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Benavides M, Laorden ML, Marín MT, Milanés MV. Role of PKC-α,γ isoforms in regulation of c-Fos and TH expression after naloxone-induced morphine withdrawal in the hypothalamic PVN and medulla oblongata catecholaminergic cell groups. J Neurochem 2005; 95:1249-58. [PMID: 16190878 DOI: 10.1111/j.1471-4159.2005.03445.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We previously demonstrated that morphine withdrawal induced hyperactivity of the hypothalamus-pituitary-adrenocortical axis by activation of noradrenergic pathways innervating the hypothalamic paraventricular nucleus (PVN), as evaluated by Fos expression and corticosterone release. The present study was designed to investigate the role of protein kinase C (PKC) in this process by estimating changes in PKCalpha and PKCgamma immunoreactivity, and whether pharmacological inhibition of PKC would attenuate morphine withdrawal-induced c-Fos expression and changes in tyrosine hydroxylase (TH) immunoreactivity levels in the PVN and nucleus tractus solitarius/ ventrolateral medulla (NTS/VLM). Dependence on morphine was induced in rats by 7 day s.c. implantation of morphine pellets. Morphine withdrawal was induced on day 8 by an injection of naloxone. The protein levels of PKCalpha and gamma were significantly down-regulated in the PVN and NTS/VLM from the morphine-withdrawn rats. Morphine withdrawal induced c-Fos expression in the PVN and NTS/VLM, indicating an activation of neurons in those nuclei. TH immunoreactivity was increased in the NTS/VLM after induction of morphine withdrawal, whereas there was a decrease in TH levels in the PVN. Infusion of calphostin C, a selective protein kinase C inhibitor, produced a reduction in the morphine withdrawal-induced c-Fos expression. Additionally, the changes in TH levels in the PVN and NTS/VLM were significantly modified by calphostin C. The present results suggest that activated PKC in the PVN and catecholaminergic brainstem cell groups may be critical for the activation of the hypothalamic-pituitary adrenocortical axis in response to morphine withdrawal.
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Affiliation(s)
- Marta Benavides
- Equip of Cellular and Molecular Pharmacology, University School of Medicine, Murcia, Spain
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24
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Ozaki S, Narita M, Narita M, Ozaki M, Khotib J, Suzuki T. Role of extracellular signal-regulated kinase in the ventral tegmental area in the suppression of the morphine-induced rewarding effect in mice with sciatic nerve ligation. J Neurochem 2004; 88:1389-97. [PMID: 15009639 DOI: 10.1046/j.1471-4159.2003.02272.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We recently reported that micro-opioid receptor agonist morphine failed to induce its rewarding effects in rodents with sciatic nerve injury. In the present study, we investigated whether a state of neuropathic pain induced by sciatic nerve ligation could change the activities of the extracellular signal-regulated kinase (ERK) and p38 in the mouse lower midbrain area including the ventral tegmental area (VTA), and these changes could directly affect the development of the morphine-induced rewarding effect in mice. The sciatic nerve ligation caused a long-lasting and profound thermal hyperalgesia. A dose-dependent place preference induced by s.c. administration of morphine was observed in sham-operated mice, but not in sciatic nerve-ligated mice. We found here for the first time that nerve injury produces a sustained and significant reduction in protein levels of phosphorylated-ERK and -p38 in cytosolic preparations of the mouse lower midbrain. The inhibition of ERK activity by i.c.v. pre-treatment with either PD98059 or U0126 impaired the morphine-induced place preference. In contrast, i.c.v. treatment with a specific inhibitor of p38, SB203580, did not interfere with the morphine-induced rewarding effect. Immunohistochemical study showed a drastic reduction in phosphorylated-ERK immunoreactivity within tyrosine hydroxylase-positive cells of the VTA. These results suggest that a sustained reduction in the ERK-dependent signalling pathway in dopamine cells of the VTA may be implicated in the suppression of the morphine-induced rewarding effect under neuropathic pain.
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Affiliation(s)
- Satoru Ozaki
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Shinagawa-ku, Tokyo, Japan
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25
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Walwyn WM, Keith DE, Wei W, Tan AM, Xie CW, Evans CJ, Kieffer BL, Maidment NT. Functional coupling, desensitization and internalization of virally expressed mu opioid receptors in cultured dorsal root ganglion neurons from mu opioid receptor knockout mice. Neuroscience 2004; 123:111-21. [PMID: 14667446 DOI: 10.1016/j.neuroscience.2003.08.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although mu opioid receptors desensitize in various cell lines in vitro, the relationship of this change in signaling efficacy to the development of tolerance in vivo remains uncertain. It is clear that a system is needed in which functional mu opioid receptor expression is obtained in appropriate neurons so that desensitization can be measured, manipulated, and mutated receptors expressed in this environment. We have developed a recombinant system in which expression of a flag-tagged mu opioid receptor is returned to dorsal root ganglia neurons from mu opioid receptor knockout mice in vitro. Flow cytometry analysis showed that adenoviral-mediated expression of the amino-terminal flag-tagged mu opioid receptor in neurons resulted in approximately 1.3x10(6) receptors/cell. Many mu opioid receptor cell lines express a similar density of receptors but this is approximately 7x greater than the number of endogenous receptors expressed by matched wild-type neurons. Inhibition of the high voltage-activated calcium currents in dorsal root ganglia neurons by the mu agonist, D-Ala(2), N-MePhe(4), Gly(5)-ol-enkephalin (DAMGO), was not different between the endogenous and flag-tagged receptor at several concentrations of DAMGO used. Both receptors desensitized equally over the first 6 h of DAMGO pre-incubation, but after 24 h the response of the endogenous receptor to DAMGO had desensitized further than the flag- tagged receptor (71+/-3 vs 29+/-7% respectively; P<0.002), indicating less desensitization in neurons expressing a higher density of receptor. Using flow cytometry to quantify the percentage of receptors remaining on the neuronal cell surface, the flag-tagged receptor internalized by 17+/-1% after 20 min and 55+/-2% after 24 h of DAMGO. These data indicate that this return of function model in neurons recapitulates many of the characteristics of endogenous mu opioid receptor function previously identified in non-neuronal cell lines.
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MESH Headings
- Animals
- Cell Line
- Cells, Cultured
- Cytomegalovirus/genetics
- Cytomegalovirus/metabolism
- DNA, Viral/biosynthesis
- DNA, Viral/genetics
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Humans
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neurons/drug effects
- Neurons/metabolism
- Receptors, Opioid, mu/deficiency
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
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Affiliation(s)
- W M Walwyn
- Department of Psychiatry and Biobehavioral Sciences, Neuropsychiatric Institute, 760 Westwood Plaza, University of California at Los Angeles, Los Angeles, CA 90024-1759, USA.
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26
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Kivell BM, Day DJ, McDonald FJ, Miller JH. Mu and delta opioid receptor immunoreactivity and mu receptor regulation in brainstem cells cultured from late fetal and early postnatal rats. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2004; 149:9-19. [PMID: 15013624 DOI: 10.1016/j.devbrainres.2003.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/25/2003] [Indexed: 10/26/2022]
Abstract
Cultured cells from the rat brainstem were used to study opioid receptor (OpR) expression during late fetal and early postnatal development. Mu and delta opioid receptor (MOR and DOR) expression was investigated from embryonic day 16 (E16) to 6 days postnatal (P6). Postnatal neurons showed more intense MOR immunoreactivity (IR) than neurons cultured from fetal brainstem (P < 0.006). DOR IR showed a similar pattern, but the differences between fetal and neonatal animals were not statistically significant. Using confocal microscopy, MOR and DOR IR were shown to be present on both the cell membrane and within the cytoplasm, in a similar pattern to the IR seen in SH-SY5Y neuroblastoma cells that endogenously express both MOR and DOR. Double-labeling experiments demonstrated colocalization of MOR and DOR in the same brainstem neurons; however, not all MOR IR regions of a single neuron were also positively stained for DOR, and not all DOR IR regions were also positive for MOR. MOR was down-regulated after a 1- or 2-h treatment with 1 microM DAMGO, a potent mu opioid agonist, in both non-transfected and MOR-transfected SH-SY5Y cells and in primary cell cultures. It was concluded that many brainstem neurons express functional MOR or DOR or coexpress both receptors, although intracellular distributions of the receptors are unique for each receptor type.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Animals, Newborn
- Astrocytes/metabolism
- Blotting, Western/methods
- Brain Stem/cytology
- Brain Stem/embryology
- Brain Stem/growth & development
- Cell Count/methods
- Cells, Cultured
- Cloning, Molecular/methods
- Embryo, Mammalian
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Gene Expression Regulation, Developmental/physiology
- Humans
- Immunohistochemistry/methods
- Kidney
- Microtubule-Associated Proteins/metabolism
- Neuroblastoma
- Neurons/metabolism
- Rats
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/metabolism
- Swine
- Time Factors
- Transfection
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Affiliation(s)
- Bronwyn M Kivell
- School of Biological Sciences, Victoria University, P.O. Box 600, Wellington, New Zealand
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27
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Harlan RE, Kailas SR, Tagoe CEF, Garcia MM. Morphine actions in the rat forebrain: role of protein kinase C. Brain Res Bull 2004; 62:285-95. [PMID: 14709343 DOI: 10.1016/j.brainresbull.2003.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Acute administration of morphine induces expression of the immediate-early gene (IEG) c-Fos in dorsomedial striatum, portions of cerebral cortex, and in several midline-intralaminar thalamic nuclei, partly via a trans-synaptic mechanism that involves activation of glutamate receptors. Because activation of protein kinase C (PKC) may occur following the activation of glutamate receptors, we determined whether pharmacological inhibition of PKC would attenuate morphine-induced c-Fos expression, and whether acute administration of morphine would induce translocation of PKC. The selective PKC antagonist NPC 15437 given 30 min prior to morphine significantly decreased morphine-induced c-Fos expression in striatum and cingulate cortex, but not in centrolateral thalamus. In another experiment, rats were given an acute dose of morphine, and immunocytochemical analysis was performed for the betaI and betaII isoforms of PKC. Morphine induced a rapid and transient translocation of PKC betaII, but not betaI, from perinuclear spots to plasma membrane in numerous cortical and striatal neurons. Prior administration of naloxone blocked this response. Ultrastructural studies confirmed translocation from Golgi apparatus to plasma membrane 15 min after morphine injection. Double immunocytochemistry at the light microscopic level demonstrated co-localization of translocated PKC betaII and c-Fos in some cortical neurons 90 min after morphine injection. These results support a role for PKC, especially PKC betaII, in the rapid effects of morphine on the brain.
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Affiliation(s)
- Richard E Harlan
- Department of Structural and Cellular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, SL-49, New Orleans, LA 70112, USA.
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28
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Fleegal MA, Sumners C. Drinking behavior elicited by central injection of angiotensin II: roles for protein kinase C and Ca2+/calmodulin-dependent protein kinase II. Am J Physiol Regul Integr Comp Physiol 2003; 285:R632-40. [PMID: 12738610 DOI: 10.1152/ajpregu.00151.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prior studies utilizing neurons cultured from the hypothalamus and brain stem of newborn rats have demonstrated that ANG II-induced modulation of neuronal firing involves activation of both protein kinase C (PKC) and Ca2+/calmodulin-dependent protein kinase II (CaMKII). The present studies were performed to determine whether these signaling molecules are also involved in physiological responses elicited by ANG II in the brain in vivo. Central injection of ANG II (10 ng/2 microl) into the lateral cerebroventricle (icv) of Sprague-Dawley rats increased water intake in a time-dependent manner. This ANG II-mediated dipsogenic response was attenuated by central injection of the PKC inhibitors chelerythrine chloride (0.5-50 microM, 2 microl) and Go-6976 (2.3 nM, 2 microl) and by the CaMKII inhibitor KN-93 (10 microM, 2 microl). Conversely, icv injection of chelerythrine chloride (50 microM, 2 microl) and KN-93 (10 microM, 2 microl) had no effect on the dipsogenic response elicited by central injection of carbachol (200 ng/2 microl). Furthermore, injection of ANG II (10 ng/2 microl) icv increases the activity of both PKC-alpha and CaMKII in rat septum and hypothalamus. These data suggest that signaling molecules involved in ANG II-induced responses in vitro are also relevant in physiological responses elicited by ANG II in the whole animal model.
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Affiliation(s)
- Melissa A Fleegal
- Dept. of Physiology and Functional Genomics, P.O. Box 100274, Univ. of Florida, Gainesville, FL 32610, USA
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29
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Rubovitch V, Gafni M, Sarne Y. The mu opioid agonist DAMGO stimulates cAMP production in SK-N-SH cells through a PLC-PKC-Ca++ pathway. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 110:261-6. [PMID: 12591162 DOI: 10.1016/s0169-328x(02)00656-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The mu-opioid agonist DAMGO exerts a dual activity on cAMP production in SK-N-SH neuroblastoma cells. While the classic inhibitory effect was prevented by pretreating the cells with pertussis toxin (PTX), the stimulatory activity was PTX-resistant. The stimulatory effect was abolished by the selective phospholipase C (PLC) blocker U-73122, by the selective protein kinase C (PKC) blocker chelerythrine and by the calcium-channels blockers Ni++, Co++ and Cd++. Hence, it is suggested that the opioid receptor activates PLC (probably through Gq GTP-binding proteins), to mobilize PKC, that positively modulates calcium channels in the plasma membrane; the entry of Ca++ into the cells stimulates calcium-activated adenylyl cyclases to produce cAMP.
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Affiliation(s)
- Vardit Rubovitch
- The Mauerberger Chair in Neuropharmacology, Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
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30
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Liu XH, Huang DA, Yang FY, Hao YS, Du GG, Li PF, Li G. A new cytokine: the possible effect pathway of methionine enkephalin. World J Gastroenterol 2003; 9:169-73. [PMID: 12508376 PMCID: PMC4728236 DOI: 10.3748/wjg.v9.i1.169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate experimentally the effects of methionine enkephalin on signal transduction of mouse myeloma NS-1 cells.
METHODS: The antigen determinate of delta opioid receptor was designed in this lab and the polypeptide fragment of antigen determinate with 12 amino acids residues was synthesized. Monoclonal antibody against this peptide fragment was prepared. Proliferation of Mouse NS-1 cells treated with methionine enkephalin of 1 × 10-6 mol·L-1 was observed. The activities of protein kinase A (PKA) and protein kinase C (PKC) were measured and thereby the mechanism of effect of methionine enkephalin was postulated.
RESULTS: The results demonstrated that methionine enkephalin could enhance the proliferation of NS-1 cells and the effect of methionine enkephalin could be particularly blocked by monoclonal antibody. The activity of PKA was increased in both cytosol and cell membrane. With reference to PKC, the intracellular activity of PKC in NS-1 cells was elevated at 1 × 10-7 mol·L-1 and then declined gradually as the concentration of methionine enkephalin was raised. The effects of methionine enkephalin might be reversed by both naloxone and monoclonal antibody.
CONCLUSION: Coupled with the findings, it in-dicates that the signal transduction systems via PKA and PKC are involved in the effects of methionine enkephalin by binding with the traditional opioid receptors, and therefore resulting in different biological effects.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Cytokines
- Enkephalin, Methionine/metabolism
- Enkephalin, Methionine/pharmacology
- Mice
- Mice, Inbred BALB C
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Protein Kinase C/metabolism
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/immunology
- Receptors, Opioid, delta/metabolism
- Signal Transduction/drug effects
- Tumor Cells, Cultured
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Affiliation(s)
- Xin-Hua Liu
- Department of Biochemistry and Molecular Biology, Health Science Center, Peking University, Beijing 100083, China
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31
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Conditional rescue of protein kinase C epsilon regulates ethanol preference and hypnotic sensitivity in adult mice. J Neurosci 2002. [PMID: 12427847 DOI: 10.1523/jneurosci.22-22-09905.2002] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Conventional gene targeting is a powerful tool to study the influence of specific genes on behavior. However, conclusions relevant for adult animals are limited by consequences of gene loss during development. Mice lacking protein kinase C epsilon (PKCepsilon) consume less alcohol and show greater acute sensitivity to alcohol than do wild-type mice. There are no selective inhibitors of PKCepsilon that can be administered systemically and cross the blood-brain barrier to test whether these phenotypes result from loss of PKCepsilon during development or in adulthood. Here we used conditional expression of PKCepsilon in the basal forebrain, amygdala, and cerebellum to rescue wild-type responses to alcohol in adult PKCepsilon(-/-) mice. Subsequent suppression of transgenic PKCepsilon restored PKCepsilon(-/-) behaviors. These findings establish that PKCepsilon signaling in the adult brain regulates alcohol consumption and sensitivity. If this extends to humans, then PKCepsilon inhibitors might prove useful as novel therapeutics for alcoholism.
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32
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Kelley AE, Bakshi VP, Haber SN, Steininger TL, Will MJ, Zhang M. Opioid modulation of taste hedonics within the ventral striatum. Physiol Behav 2002; 76:365-77. [PMID: 12117573 DOI: 10.1016/s0031-9384(02)00751-5] [Citation(s) in RCA: 411] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a long-standing interest in the role of endogenous opioid peptides in feeding behavior and, in particular, in the modulation of food reward and palatability. Since drugs such as heroin, morphine, alcohol, and cannabinoids, interact with this system, there may be important common neural substrates between food and drug reward with regard to the brain's opioid systems. In this paper, we review the proposed functional role of opioid neurotransmission and mu opiate receptors within the nucleus accumbens and surrounding ventral striatum. Opioid compounds, particularly those selective for the mu receptor, induce a potent increase in food intake, sucrose, salt, saccharin, and ethanol intake. We have explored this phenomenon with regard to macronutrient selection, regional specificity, role of output structures, Fos mapping, analysis of motivational state, and enkephalin gene expression. We hypothesize that opioid-mediated mechanisms within ventral striatal medium spiny neurons mediate the affective or hedonic response to food ('liking' or food 'pleasure'). A further refinement of this hypothesis is that activation of ventral striatal opioids specifically encodes positive affect induced by tasty and/or calorically dense foods (such as sugar and fat), and promotes behaviors associated with this enhanced palatability. It is proposed that this brain mechanism was beneficial in evolutionary development for ensuring the consumption of relatively scarce, high-energy food sources. However, in modern times, with unlimited supplies of high-calorie food, it has contributed to the present epidemic of obesity.
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Affiliation(s)
- A E Kelley
- Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd., Madison, WI 53719, USA.
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33
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Bartlett SE, Reynolds AJ, Weible M, Hendry IA. Phosphatidylinositol kinase enzymes regulate the retrograde axonal transport of NT-3 and NT-4 in sympathetic and sensory neurons. J Neurosci Res 2002; 68:169-75. [PMID: 11948662 DOI: 10.1002/jnr.10201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Phosphatidylinositol 3-kinase (PI3-kinase) and phosphatidylinositol 4-kinase (PI4-kinase) enzymes are an important family of signaling molecules that have been implicated in the regulation of intracellular vesicle trafficking. It has previously been shown that PI3-kinase and PI4-kinase enzymes regulate neuronal survival and the retrograde axonal transport of nerve growth factor in sympathetic and sensory neurons. We have extended these studies to examine the role these enzymes play in the regulation of the retrograde axonal transport of neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) in sympathetic and sensory neurons in vivo. Wortmannin (0.1 nmol/eye), a PI3-kinase and PI4-kinase antagonist, reduced the amount of (125)I-NT-3 retrograde transport in sympathetic neurons by approximately 50% and (125)I-NT-4 in sympathetic neurons by approximately 40% and sensory neurons by approximately 20%. The PI3-kinase antagonist LY294002 (100 nmol/eye) reduced the retrograde axonal transport of (125)I-NT-4 in sympathetic and sensory neurons, and (125)I-NT-3 in sympathetic neurons. Phenylarsine oxide (PAO), a PI4-kinase antagonist, significantly inhibited (125)I-NT-4 retrograde axonal transport in sympathetic and sensory neurons. These results show that wortmannin-sensitive PI3-kinases and PI4-kinases may be involved in NT-3 and NT-4 retrograde axonal transport. The retrograde axonal transport of neurotrophic factors in sympathetic and sensory neurons in vivo appears to depend upon the activation of different receptors and second messenger cascades at the nerve terminal.
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Affiliation(s)
- Selena E Bartlett
- Division of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601, Australia
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34
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Liu QR, Zhang PW, Zhen Q, Walther D, Wang XB, Uhl GR. KEPI, a PKC-dependent protein phosphatase 1 inhibitor regulated by morphine. J Biol Chem 2002; 277:13312-20. [PMID: 11812771 DOI: 10.1074/jbc.m107558200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
cDNAs encoding KEPI, a novel protein kinase C (PKC)-potentiated inhibitory protein for type 1 Ser/Thr protein phosphatase (PP1), were identified. They were found among morphine-regulated brain mRNAs identified using subtracted differential display techniques. Full-length rat, mouse, and human cDNA and genomic sequences were elucidated with library screening and data base searching. Rat, mouse, and human KEPI cDNAs encode 164-165 amino acid proteins with calculated isoelectric points of 5.2. Each species' amino acid sequence contains consensus sequences for phosphorylation by PKC (KVT(72)VK), protein kinase A (RKLS(154)), and casein kinase II (S(43)SRE, S(120)EEE). Multiple KEPI N-terminal myristoylation consensus sites provide potential regions for membrane anchoring. Subcellular fractionation and Western analyses revealed that most KEPI immunoreactivity was associated with P2 and P3 membrane-enriched fractions and little in cytosolic fractions. 2.6-kb KEPI mRNAs were detected in brain, especially in the cerebral cortex and hippocampus, and in heart and skeletal muscle. Brain KEPI mRNA was up-regulated by both acute and chronic morphine treatments. The human KEPI gene contains four exons extending over more than 100 kb of genomic sequence on 6q24-q25, near the mu opiate receptor gene. These sequences displayed sufficient homology with the porcine PP1 inhibitor CPI-17 that we asked whether KEPI could share the ability of CPI-17 to modulate PP1 activity in a PKC-dependent fashion. Recombinant mouse KEPI is phosphorylated by PKC with a K(m) of 2.6 microm and a t(1/2) of 20 min. Phospho-KEPI inhibits PP1alpha with an IC(50) of 2.7 nm, a potency more than 600-fold greater than that displayed by unphosphorylated KEPI. Neither phospho- nor dephospho-KEPI inhibits protein phosphatase 2A. Up-regulation of KEPI expression by morphine, an agonist at PKC-regulating G-protein-coupled mu receptors, provides a novel signaling paradigm in which the half-lives of serine/threonine phosphorylation events can be influenced by activities at G(i)/G(o)-coupled receptors that modulate KEPI expression, KEPI phosphorylation, and KEPI regulation of PP1 activity.
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Affiliation(s)
- Qing-Rong Liu
- Molecular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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35
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Li AH, Wang HL. G protein-coupled receptor kinase 2 mediates mu-opioid receptor desensitization in GABAergic neurons of the nucleus raphe magnus. J Neurochem 2001; 77:435-44. [PMID: 11299306 DOI: 10.1046/j.1471-4159.2001.00267.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nucleus raphe magnus (NRM) sends the projection to spinal dorsal horn and inhibits nociceptive transmission. Analgesic effect produced by mu-opioid receptor agonists including morphine partially results from activating the NRM-spinal cord pathway. It is generally believed that mu-opioid receptor agonists disinhibit spinally projecting neurons of the NRM and produce analgesia by hyperpolarizing GABAergic interneurons. In the present study, whole-cell patch-clamp recordings combined with single-cell RT-PCR analysis were used to test the hypothesis that DAMGO ([D-Ala(2),N-methyl-Phe(4),Gly-ol(5)]enkephalin), a specific mu-opioid receptor agonist, selectively hyperpolarizes NRM neurons expressing mRNA of glutamate decarboxylase (GAD(67)). Homologous desensitization of mu-opioid receptors in NRM neurons could result in the development of morphine-induced tolerance. G protein-coupled receptor kinase (GRK) is believed to mediate mu-opioid receptor desensitization in vivo. Therefore, we also investigated the involvement of GRK in mediating homologous desensitization of DAMAMGO-induced electrophysiological effects on NRM neurons by using two experimental strategies. First, single-cell RT-PCR assay was used to study the expression of GRK2 and GRK3 mRNAs in individual DAMGO-responsive NRM neurons. Whole-cell recording was also performed with an internal solution containing the synthetic peptide, which corresponds to G(betagamma)-binding domain of GRK and inhibits G(betagamma) activation of GRK. Our results suggest that DAMGO selectively hyperpolarizes NRM GABAergic neurons by opening inwardly rectifying K(+) channels and that GRK2 mediates short-term homologous desensitization of mu-opioid receptors in NRM GABAergic neurons.
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MESH Headings
- Amino Acid Sequence
- Analgesics, Opioid/pharmacology
- Animals
- Binding Sites
- Cyclic AMP-Dependent Protein Kinases/biosynthesis
- Cyclic AMP-Dependent Protein Kinases/genetics
- Cyclic AMP-Dependent Protein Kinases/physiology
- Drug Tolerance/physiology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- G-Protein-Coupled Receptor Kinase 2
- G-Protein-Coupled Receptor Kinase 3
- Glutamate Decarboxylase/biosynthesis
- Ion Transport/drug effects
- Membrane Potentials/drug effects
- Molecular Sequence Data
- Nerve Tissue Proteins/biosynthesis
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Neurons/drug effects
- Neurons/physiology
- Oligopeptides/chemical synthesis
- Oligopeptides/pharmacology
- Pain/physiopathology
- Patch-Clamp Techniques
- Phosphorylation
- Potassium/metabolism
- Potassium Channels/metabolism
- Potassium Channels, Inwardly Rectifying
- Protein Processing, Post-Translational
- Protein Serine-Threonine Kinases/biosynthesis
- Protein Serine-Threonine Kinases/genetics
- Protein Structure, Tertiary
- Protein Transport/drug effects
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Raphe Nuclei/drug effects
- Raphe Nuclei/enzymology
- Raphe Nuclei/physiology
- Raphe Nuclei/physiopathology
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/drug effects
- Spinal Cord/physiopathology
- beta-Adrenergic Receptor Kinases
- gamma-Aminobutyric Acid/physiology
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Affiliation(s)
- A H Li
- Department of Anesthesiology, Chang Gung Memorial Hospital, Taiwan, China Department of Physiology, Chang Gung University School of Medicine, Kwei-San, Tao-Yuan, Taiwan, China
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36
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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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Shen J, Benedict Gomes A, Gallagher A, Stafford K, Yoburn BC. Role of cAMP-dependent protein kinase (PKA) in opioid agonist-induced mu-opioid receptor downregulation and tolerance in mice. Synapse 2000; 38:322-7. [PMID: 11020235 DOI: 10.1002/1098-2396(20001201)38:3<322::aid-syn11>3.0.co;2-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Studies suggest that acute and chronic opioids can regulate the cAMP-dependent protein kinase (PKA) signaling pathway and that changes in this pathway may be involved in opioid tolerance. In the present study, we examined the role of cAMP-PKA on mu-opioid receptor downregulation and tolerance in mice. Mice were injected intracerebroventricular (i.c.v.) and intrathecal (i.t.) once a day with an antisense oligodeoxynucleotide directed at the mRNA for the alpha catalytic subunit of mouse PKA. Controls were treated with saline or a mismatch oligodeoxynucleotide. On day 2 of treatment, mice were implanted s.c. with a 25-mg morphine pellet and an osmotic minipump infusing morphine (40 mg/kg/day) for 3 days. Other mice were implanted with an osmotic minipump infusing etorphine (125, 250 microg/kg/day) for 2 days. Control mice were implanted s.c. with inert placebo pellets. At the end of treatment, pumps and pellets were removed and mice tested for morphine or etorphine analgesia. Other mice were sacrificed and mu-opioid receptor binding assays conducted in whole brain. Both infusion doses of etorphine produced significant tolerance (ED(50) shift = 3.6 and 6.3-fold). The higher etorphine infusion produced downregulation of mu-receptor density ( approximately 30%) while the lower infusion dose of etorphine did not. Morphine treatment also produced significant tolerance in mice (ED(50) shift = 4.5-fold), but no receptor downregulation. Antisense to PKA partially blocked tolerance induced by the higher dose of etorphine, but had no effect on receptor downregulation. On the other hand, antisense to PKA completely blocked tolerance induced by morphine and the lower infusion dose of etorphine. The mismatch oligodeoxynucleotide had no effect on any measure. These results suggest that PKA has a limited role in opioid agonist-induced receptor downregulation. However, the partial block of tolerance for the high infusion dose of etorphine and the complete block of tolerance for morphine and the low infusion dose of etorphine suggests that PKA may play a critical role in tolerance that is "receptor-regulation-independent."
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Affiliation(s)
- J Shen
- Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John's University, Queens, New York 11439, USA
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38
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Harrison C, Rowbotham DJ, Grandy DK, Lambert DG. Endomorphin-1 induced desensitization and down-regulation of the recombinant mu-opioid receptor. Br J Pharmacol 2000; 131:1220-6. [PMID: 11082131 PMCID: PMC1572439 DOI: 10.1038/sj.bjp.0703683] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. Endomorphin-1 (E1) is a peptide with high affinity and selectivity for the mu-opioid receptor. The aim of this study was to determine if endomorphin-1 caused desensitization and down-regulation of the mu-opioid receptor expressed in Chinese hamster ovary cells. 2. Following 10 microM E1 pre-treatment, desensitization was assessed by measuring cyclic AMP inhibition, down-regulation was assessed by [(3)H]-diprenorphine ([(3)H]-DPN) binding and immuno-blotting. 3. Pre-treatment of CHO mu cells with 10 microM E1 for 11 and 18 h caused significant reduction in cyclic AMP inhibition. (11 h=39.0+/-16.7%, 18 h 47.0+/-11.1% reduction). 4. At 18 h E1 pre-treatment there was an enhancement (4.5 fold) of cyclic AMP production under forskolin stimulated conditions accompanied by a small rightward shift in the concentration-response curve (pEC(50) control=7.8+/-0.3, pEC(50) E1=7.3+/-0.2) when cells were re-challenged with E1. 5. In membranes prepared from untreated and 0.5 h E1 pre-treated cells, addition of GTP gamma S produced a significant rightward shift in the concentration response curves for E1 displacement of [(3)H]-DPN (0 h K(i) control=7.86+/-0.11, GTP gamma S=7.37+/-0.15; 0.5 h K(i) control=7.92+/-0.12, GTP gamma S=7.36+/-0.08) This was not observed in membranes prepared from cells that had been treated with E1 for 18 h (18 h K(i) control=7.69+/-0. 11, GTP gamma S=7.75+/-0.08). 6. In whole cells E1 treatment caused a rapid loss of cell surface receptors such that at 0.5 h there was a 30.5+/-1.5 reduction (this was unchanged for 18 h). In crude membranes a loss of receptors was also observed using radioligand binding or immuno-blotting protocols. 7. These data show that E1 causes desensitization and down-regulation of the rat mu-opioid receptor expressed in CHO cells. However, these two responses appear temporally distinct.
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Affiliation(s)
- C Harrison
- University Department of Anaesthesia and Pain Management, Leicester Royal Infirmary, Leicester LE1 5WW
| | - D J Rowbotham
- University Department of Anaesthesia and Pain Management, Leicester Royal Infirmary, Leicester LE1 5WW
| | - D K Grandy
- Vollum Institute for Advanced Biomedical Research, Portland, Oregon, OR 97201-3089 U.S.A
| | - D G Lambert
- University Department of Anaesthesia and Pain Management, Leicester Royal Infirmary, Leicester LE1 5WW
- Author for correspondence:
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Kramer HK, Andria ML, Kushner SA, Esposito DH, Hiller JM, Simon EJ. Mutation of tyrosine 318 (Y318F) in the delta-opioid receptor attenuates tyrosine phosphorylation, agonist-dependent receptor internalization, and mitogen-activated protein kinase activation. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 79:55-66. [PMID: 10925143 DOI: 10.1016/s0169-328x(00)00097-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Opioid receptors are known for their ability to activate diverse second messenger systems. Previously, we showed that selective delta-opioid agonists were able to induce the rapid tyrosine phosphorylation of delta-opioid receptors (delta-ORs) through Src. Src-dependent tyrosine phosphorylation of delta-ORs appears to be important for activation of the mitogen-activated protein kinase cascade and for receptor sequestration into clathrin-coated endosomes, as the Src antagonist, PP1, inhibited both. In an attempt to clarify the role of tyrosine phosphorylation in delta-OR signalling and regulation, we constructed a mutant receptor in which the tyrosine located in the conserved NPXXY motif of the C-terminus was replaced by a phenylalanine (Y318F-delta-OR). Mutation of Y318 resulted in a receptor that was comparable to the wild type in its expression level in HEK-293 cells and in its affinity for opioid ligands. Both receptors showed effective coupling to G proteins and were capable of inhibiting forskolin-stimulated cAMP accumulation with similar potencies. However, the mutant receptor was able to stimulate (35)S-GTPgammaS binding with a lower EC(50) than the wild type receptor. The stimulation of tyrosine phosphorylation in delta-ORs by [D-Thr(2)]-Leu-enkephalin-Thr (DTLET) was significantly less in cells expressing the Y318F-delta-OR than in cells expressing the wild type. In addition, both rapid receptor internalization and down-regulation were markedly attenuated in the mutant. Finally, the mutant receptor was unable to induce a robust activation of the MAPK pathway, suggesting that tyrosine phosphorylation of the delta-OR protein is important for this signalling pathway. These findings implicate tyrosine phosphorylation of Y318 in receptor signalling and agonist-mediated regulation.
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Affiliation(s)
- H K Kramer
- Department of Psychiatry, New York University School of Medicine, Millhauser Laboratories-Room HN-610, New York, NY 10016, USA.
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40
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Wang D, Tolbert LM, Carlson KW, Sadée W. Nuclear Ca2+/calmodulin translocation activated by mu-opioid (OP3) receptor. J Neurochem 2000; 74:1418-25. [PMID: 10737597 DOI: 10.1046/j.1471-4159.2000.0741418.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous evidence has suggested a role for calmodulin (CaM) in opioid receptor signaling. We demonstrate here that morphine stimulation of the mu-opioid (OP3) receptor causes rapid CaM translocation to the nucleus in OP3-transfected human embryonic kidney (HEK)-293 cells and in SH-SY5Y human neuroblastoma cells. Ca2+ influx into the cells resulting from OP3 receptor activation was required for nuclear CaM translocation. Moreover, in HEK-OP3 and SH-SY5Y cells, increased nuclear CaM content was associated with enhanced phosphorylation of the nuclear transcription factor cyclic AMP-responsive element-binding protein. This appeared to be mediated by Ca2+/CaM kinases and also by a pathway involving protein kinase C. CaM was previously shown to bind directly to the OP3 receptor and to be released from the plasma membrane on agonist stimulation. To test whether OP3-mediated CaM release contributes to nuclear CaM signaling, we used a mutant OP3 receptor (K273A) with reduced affinity for CaM that fails to release CaM from the plasma membrane. K273A-OP3 activated Ca2+ influx to a similar extent as wild-type OP3; however, CaM translocation to the nucleus was attenuated. These results indicate that OP3-stimulated Ca2+ influx results in nuclear CaM translocation, which appears to be enhanced by simultaneous CaM release by OP3 wild-type receptor from plasma membranes. These results suggest a novel Ca2+/CaM signaling pathway of opioid receptors in the regulation of transcriptional activity.
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Affiliation(s)
- D Wang
- Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, School of Pharmacy, University of California San Francisco, 94143-0446, USA
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41
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Onoprishvili I, Andria ML, Vilim FS, Hiller JM, Simon EJ. The bovine mu-opioid receptor: cloning of cDNA and pharmacological characterization of the receptor expressed in mammalian cells. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 73:129-37. [PMID: 10581406 DOI: 10.1016/s0169-328x(99)00249-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cDNA coding for the bovine mu-opioid receptor has been cloned and sequenced. Conserved sequences from murine delta-receptor cDNA were used as primers in polymerase chain reaction (PCR) to amplify cDNA, prepared by reverse transcription of bovine brain mRNA. This cDNA was used to probe a bovine brain library. The partial sequence obtained was extended to provide the full length clone by PCR. The cDNA has an open reading frame of 1203 base pairs (bp) with a 3'-untranslated region of 1900 bp and a 5'-untranslated region of 265 bp. The protein contains 401 amino acids and has 94% amino acid identity with the human and 91% with the rat mu-opioid receptor. It has the putative seven transmembrane domains, characteristic of G protein-coupled receptors and contains 5 potential N-linked glycosylation sites near the N-terminus. Several potential phosphorylation sites and a putative palmitoylation site are also present. The receptor was stably expressed in HEK293 cells. The binding profile was found to be that of a typical mu receptor, i. e., mu agonists and antagonists, but not delta and kappa ligands, bound with high affinity. Functional assays, namely, opioid stimulation of [35S]GTPgammaS binding and inhibition of forskolin-activated adenylyl cyclase, were also found to be highly specific for mu-opioid agonists. The receptor was downregulated by chronic exposure to mu agonists but not delta or kappa agonists. Evidence is presented indicating that the cloned receptor is the same as the bovine mu receptor previously purified to homogeneity in our laboratory. No evidence was found for genes for multiple mu-type opioid receptors.
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MESH Headings
- Adenylyl Cyclases/drug effects
- Adenylyl Cyclases/metabolism
- Amino Acid Sequence
- Analgesics, Opioid/metabolism
- Analgesics, Opioid/pharmacology
- Animals
- Base Sequence
- Benzeneacetamides
- Binding, Competitive/drug effects
- Cattle
- Cell Line
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cloning, Molecular
- Colforsin/pharmacology
- Corpus Striatum/chemistry
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Diprenorphine/metabolism
- Diprenorphine/pharmacology
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalin, D-Penicillamine (2,5)-/metabolism
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Gene Expression
- Gene Expression Regulation/drug effects
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Molecular Sequence Data
- Pyrrolidines/metabolism
- Pyrrolidines/pharmacology
- Radioligand Assay
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sulfur Radioisotopes
- Tritium
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Affiliation(s)
- I Onoprishvili
- Department of Psychiatry, NYU School of Medicine, New York, NY 10016, USA
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42
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Kramer HK, Simon EJ. Role of protein kinase C (PKC) in agonist-induced mu-opioid receptor down-regulation: II. Activation and involvement of the alpha, epsilon, and zeta isoforms of PKC. J Neurochem 1999; 72:594-604. [PMID: 9930731 DOI: 10.1046/j.1471-4159.1999.0720594.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phosphorylation of specific amino acid residues is believed to be crucial for the agonist-induced regulation of several G protein-coupled receptors. This is especially true for the three types of opioid receptors (mu, delta, and kappa), which contain consensus sites for phosphorylation by numerous protein kinases. Protein kinase C (PKC) has been shown to catalyze the in vitro phosphorylation of mu- and delta-opioid receptors and to potentiate agonist-induced receptor desensitization. In this series of experiments, we continue our investigation of how opioid-activated PKC contributes to homologous receptor down-regulation and then expand our focus to include the exploration of the mechanism(s) by which mu-opioids produce PKC translocation in SH-SY5Y neuroblastoma cells. [D-Ala2,N-Me-Phe4,Gly-ol]enkephalin (DAMGO)-induced PKC translocation follows a time-dependent and biphasic pattern beginning 2 h after opioid addition, when a pronounced translocation of PKC to the plasma membrane occurs. When opioid exposure is lengthened to >12 h, both cytosolic and particulate PKC levels drop significantly below those of control-treated cells in a process we termed "reverse translocation." The opioid receptor antagonist naloxone, the PKC inhibitor chelerythrine, and the L-type calcium channel antagonist nimodipine attenuated opioid-mediated effects on PKC and mu-receptor down-regulation, suggesting that this is a process partially regulated by Ca2+-dependent PKC isoforms. However, chronic exposure to phorbol ester, which depletes the cells of diacylglycerol (DAG) and Ca2+-sensitive PKC isoforms, before DAMGO exposure, had no effect on opioid receptor down-regulation. In addition to expressing conventional (PKC-alpha) and novel (PKC-epsilon) isoforms, SH-SY5Y cells also contain a DAG- and Ca2+-independent, atypical PKC isozyme (PKC-zeta), which does not decrease in expression after prolonged DAMGO or phorbol ester treatment. This led us to investigate whether PKC-zeta is similarly sensitive to activation by mu-opioids. PKC-zeta translocates from the cytosol to the membrane with kinetics similar to those of PKC-alpha and epsilon in response to DAMGO but does not undergo reverse translocation after longer exposure times. Our evidence suggests that direct PKC activation by mu-opioid agonists is involved in the processes that result in mu-receptor down-regulation in human neuroblastoma cells and that conventional, novel, and atypical PKC isozymes are involved.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Biological Transport/drug effects
- Carcinogens/pharmacology
- Diprenorphine/pharmacology
- Down-Regulation/drug effects
- Down-Regulation/physiology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, Leucine/analogs & derivatives
- Enkephalin, Leucine/pharmacology
- Enkephalins/pharmacology
- Enzyme Activation/drug effects
- Enzyme Activation/physiology
- Humans
- Immunoblotting
- Isoenzymes/analysis
- Isoenzymes/metabolism
- Narcotic Antagonists/pharmacology
- Neuroblastoma
- Phorbol 12,13-Dibutyrate/pharmacology
- Phorbol Esters/pharmacology
- Protein Kinase C/analysis
- Protein Kinase C/metabolism
- Protein Kinase C-alpha
- Protein Kinase C-epsilon
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Second Messenger Systems/physiology
- Tritium
- Tumor Cells, Cultured
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Affiliation(s)
- H K Kramer
- Department of Psychiatry, New York University Medical Center, New York 10016, USA
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