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Sari Y, Swiss GM, Alrashedi FA, Baeshen KA, Alshammari SA, Alsharari SD, Ali N, Alasmari AF, Alhoshani A, Alameen AA, Childers WE, Abou-Gharbia M, Alasmari F. Effects of novel beta-lactam, MC-100093, and ceftriaxone on astrocytic glutamate transporters and neuroinflammatory factors in nucleus accumbens of C57BL/6 mice exposed to escalated doses of morphine. Saudi Pharm J 2024; 32:102108. [PMID: 38868175 PMCID: PMC11166880 DOI: 10.1016/j.jsps.2024.102108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024] Open
Abstract
Chronic exposure to opioids can lead to downregulation of astrocytic glutamate transporter 1 (GLT-1), which regulates the majority of glutamate uptake. Studies from our lab revealed that beta-lactam antibiotic, ceftriaxone, attenuated hydrocodone-induced downregulation of GLT-1 as well as cystine/glutamate antiporter (xCT) expression in central reward brain regions. In this study, we investigated the effects of escalating doses of morphine and tested the efficacy of novel synthetic non-antibiotic drug, MC-100093, and ceftriaxone in attenuating the effects of morphine exposure in the expression of GLT-1, xCT, and neuroinflammatory factors (IL-6 and TGF-β) in the nucleus accumbens (NAc). This study also investigated the effects of morphine and beta-lactams in locomotor activity, spontaneous alternation percentage (SAP) and number of entries in Y maze since opioids have effects in locomotor sensitization. Mice were exposed to moderate dose of morphine (20 mg/kg, i.p.) on days 1, 3, 5, 7, and a higher dose of morphine (150 mg/kg, i.p.) on day 9, and these mice were then behaviorally tested and euthanized on Day 10. Western blot analysis showed that exposure to morphine downregulated GLT-1 and xCT expression in the NAc, and both MC-100093 and ceftriaxone attenuated these effects. In addition, morphine exposure increased IL-6 mRNA and TGF-β mRNA expression, and MC-100093 and ceftriaxone attenuated only the effect on IL-6 mRNA expression in the NAc. Furthermore, morphine exposure induced an increase in distance travelled, and MC-100093 and ceftriaxone attenuated this effect. In addition, morphine exposure decreased the SAP and increased the number of arm entries in Y maze, however, neither MC-100093 nor ceftriaxone showed any attenuating effect. Our findings demonstrated for the first time that MC-100093 and ceftriaxone attenuated morphine-induced downregulation of GLT-1 and xCT expression, and morphine-induced increase in neuroinflammatory factor, IL-6, as well as hyperactivity. These findings revealed the beneficial therapeutic effects of MC-100093 and ceftriaxone against the effects of exposure to escalated doses of morphine.
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Affiliation(s)
- Youssef Sari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH 43614, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ghadeer M.S. Swiss
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Fatin A. Alrashedi
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Kholoud A. Baeshen
- Department of Forensic Sciences, College of Criminal Justice, Naif Arab University for Security Sciences, Riyadh, Saudi Arabia
| | - Sultan A. Alshammari
- Department of Forensic Sciences, College of Criminal Justice, Naif Arab University for Security Sciences, Riyadh, Saudi Arabia
| | - Shakir D. Alsharari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Nemat Ali
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Abdullah F. Alasmari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ali Alhoshani
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Alaa A. Alameen
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Wayne E. Childers
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Magid Abou-Gharbia
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Fawaz Alasmari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
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Alasmari F, Sari DB, Alhaddad H, Al-Rejaie SS, Sari Y. Interactive role of acid sensing ion channels and glutamatergic system in opioid dependence. Neurosci Biobehav Rev 2022; 135:104581. [PMID: 35181397 DOI: 10.1016/j.neubiorev.2022.104581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/03/2022] [Accepted: 02/12/2022] [Indexed: 11/21/2022]
Abstract
Dysregulation in glutamatergic receptors and transporters has been found to mediate drugs of abuse, including morphine. Among glutamate receptors, ionotropic glutamate receptors (iGluRs) are altered with exposure to drugs of abuse. Acid-sensing ion channels (ASICs) are ligand (H+)-gated channels, which are expressed at the excitatory synaptic clefts and play a role in drug dependence. Overexpression of a specific ASIC subtype, ASIC1a, attenuated reinstatement of cocaine. ASICs are revealed to be involved in cocaine and morphine seeking behaviors, and these effects are mediated through modulation of glutamatergic receptors. In this review, we discussed the interactive role of ASICs and glutamate receptors, mainly iGluRs, in opioid dependence. ASICs are also expressed in astrocytes and are suggested to be involved on regulating glutamate uptake. However, little is known about the coupling between ASICs and the astroglial glutamate transporters. In addition, this review discussed the role of nitric oxide in the modulation of ASIC function and potentially opioid dependence. We also discussed the role of ASICs in the modulation of the function of both glutamatergic receptors in post-synaptic neurons and glutamatergic transporters in astrocytes in animals exposed to drugs of abuse.
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Affiliation(s)
- Fawaz Alasmari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia; Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA.
| | - Deen B Sari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Hasan Alhaddad
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Salim S Al-Rejaie
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Youssef Sari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia; Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA.
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Mongi-Bragato B, Avalos MP, Guzmán AS, García-Keller C, Bollati FA, Cancela LM. Endogenous enkephalin is necessary for cocaine-induced alteration in glutamate transmission within the nucleus accumbens. Eur J Neurosci 2020; 53:1441-1449. [PMID: 33159343 DOI: 10.1111/ejn.15035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 11/30/2022]
Abstract
Altered glutamate transmission within the nucleus accumbens (NAc) has been proposed as a central mechanism underlying behavioural sensitisation associated with repeated cocaine exposure. In addition to glutamate, enkephalin, an endogenous opioid peptide derived from proenkephalin, is necessary for the neuroadaptations associated with chronic cocaine. However, the influence of enkephalin on long-term changes in glutamate transmission within the NAc associated with cocaine-induced sensitisation has not been described. This study used knockout proenkephalin mice (KO) to study the influence of endogenous enkephalin on the adaptations in glutamate neurotransmission associated with repeated cocaine treatment. Wild-type (WT) and KO mice were treated with daily cocaine injections for 9 days to induce sensitisation. On days 15 and 21, the animals received a cocaine challenge and locomotor sensitisation was evaluated, and microdialysis was performed to determine accumbens glutamate content on day 21. No expression of behavioural sensitisation to cocaine was evidenced in the KO mice. Consistently, these showed no changes in glutamate transmission in the NAc associated with repeated cocaine. This study reveals the central role of enkephalin in regulating the glutamate mechanisms associated with cocaine sensitisation.
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Affiliation(s)
- Bethania Mongi-Bragato
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Paula Avalos
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrea S Guzmán
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Constanza García-Keller
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina.,Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA
| | - Flavia A Bollati
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Liliana M Cancela
- Departamento de Farmacología, Facultad de Ciencias Químicas, Instituto de Farmacología Experimental de Córdoba (IFEC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
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Augustine F, Rajendran S, Singer HS. Cortical endogenous opioids and their role in facilitating repetitive behaviors in deer mice. Behav Brain Res 2019; 379:112317. [PMID: 31676208 DOI: 10.1016/j.bbr.2019.112317] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 12/11/2022]
Abstract
Deer mice provide a non-pharmacologically induced model for the study of repetitive behaviors. In captivity, these animals develop frequent jumping and rearing that resemble clinical symptoms of obsessive-compulsive behavior (OCB), autism spectrum disorder (ASD), complex motor stereotypies (CMS), and Tourette's syndrome (TS). In this study, we pursue the mechanism of repetitive behaviors by performing stereological analyses and liquid chromatography/ mass spectrometry (LC-MS/MS) measurements of glutamate (Glut), GABA, 3,4-dihydroxyphenylacetic acid (DOPAC), dopamine (DA), leu-enkephalin (leu-enk), and dynorphin-A (dyn-A) in frontal cortex (FC), prefrontal cortex (PFC), and basal ganglia. The only significant stereological alteration was a negative correlation between repetitive behaviors and the cell count in the ventromedial striatum (VMS). Neurochemical analyses demonstrated a significant negative correlation between repetitive behaviors and endogenous opioids (leu-enk and dyn-A) in the FC - the site of origin of habitual behaviors and cortical projections to striatal MSNs participating in direct and indirect pathways. The precise neurochemical process by which endogenous opioids influence synaptic neurotransmission is unknown. One postulated cortical mechanism, supported by our findings, is an opioid effect on cortical interneuron GABA release and a consequent effect on glutamatergic cortical pyramidal cells. Anatomical changes in the VMS could have a role in repetitive behaviors, recognizing that this region influences goal-directed and habitual behaviors.
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Affiliation(s)
- Farhan Augustine
- Department of Neurology, Johns Hopkins University School of Medicine, USA
| | | | - Harvey S Singer
- Department of Neurology, Johns Hopkins University School of Medicine, USA.
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Liang J, Chao D, Sandhu HK, Yu Y, Zhang L, Balboni G, Kim DH, Xia Y. δ-Opioid receptors up-regulate excitatory amino acid transporters in mouse astrocytes. Br J Pharmacol 2015; 171:5417-30. [PMID: 25052197 DOI: 10.1111/bph.12857] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 07/07/2014] [Accepted: 07/17/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Astrocytic excitatory amino acid transporters (EAATs) regulate extracellular glutamate concentrations and play a role in preventing neuroexcitotoxicity. As the δ-opioid receptor (DOP receptor) is neuroprotective against excitotoxic injury, we determined whether DOP receptor activation up-regulates EAAT expression and function. EXPERIMENTAL APPROACH We measured mRNA and protein expression of EAAT1, EAAT2 and EAAT3 in cultured mouse astrocytes exposed to a specific DOP receptor agonist (UFP-512) with or without a DOP receptor antagonist, DOP receptor siRNA or inhibitors of PKC, PKA, PI3K, p38, MAPK, MEK and ERK, and evaluated the function of EAATs by measuring glutamate uptake. KEY RESULTS Astrocytic DOP receptor mRNA and protein were suppressed by DOP receptor siRNA knockdown. DOP receptor activation increased mRNA and protein expression of EAAT1 and EAAT2, but not EAAT3, thereby enhancing glutamate uptake of astrocytes. DOP receptor-induced EAAT1 and EAAT2 expression was largely reversed by DOP receptor antagonist naltrindole or by DOP receptor siRNA knockdown, and suppressed by inhibitors of MEK, ERK and p38. DOP receptor-accelerated glutamate uptake was inhibited by EAAT blockers, DOP receptor siRNA knockdown or inhibitors of MEK, ERK or p38. In contrast, inhibitors of PKA, PKC or PI3K had no significant effect on DOP receptor-induced EAAT expression. CONCLUSIONS AND IMPLICATIONS DOP receptor activation up-regulates astrocytic EAATs via MEK-ERK-p38 signalling, suggesting a critical role for DOP receptors in the regulation of astrocytic EAATs and protection against neuroexcitotoxicity. As decreased EAAT expression contributes to pathophysiology in many neurological diseases, including amyotrophic lateral sclerosis, our findings present a new platform for potential treatments of these diseases.
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Affiliation(s)
- Jianfeng Liang
- Department of Neurosurgery, The University of Texas Medical School at Houston, Houston, TX, USA; Yale University School of Medicine, New Haven, CT, USA; Department of Neurosurgery, China-Japan Friendship Hospital, Beijing, China
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Aoyama K, Nakaki T. Glutathione in Cellular Redox Homeostasis: Association with the Excitatory Amino Acid Carrier 1 (EAAC1). Molecules 2015; 20:8742-58. [PMID: 26007177 PMCID: PMC6272787 DOI: 10.3390/molecules20058742] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/11/2015] [Indexed: 12/15/2022] Open
Abstract
Reactive oxygen species (ROS) are by-products of the cellular metabolism of oxygen consumption, produced mainly in the mitochondria. ROS are known to be highly reactive ions or free radicals containing oxygen that impair redox homeostasis and cellular functions, leading to cell death. Under physiological conditions, a variety of antioxidant systems scavenge ROS to maintain the intracellular redox homeostasis and normal cellular functions. This review focuses on the antioxidant system’s roles in maintaining redox homeostasis. Especially, glutathione (GSH) is the most important thiol-containing molecule, as it functions as a redox buffer, antioxidant, and enzyme cofactor against oxidative stress. In the brain, dysfunction of GSH synthesis leading to GSH depletion exacerbates oxidative stress, which is linked to a pathogenesis of aging-related neurodegenerative diseases. Excitatory amino acid carrier 1 (EAAC1) plays a pivotal role in neuronal GSH synthesis. The regulatory mechanism of EAAC1 is also discussed.
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Affiliation(s)
| | - Toshio Nakaki
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-3-3964-3793; Fax: +81-3-3964-0602
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Chronic exposure to morphine decreases the expression of EAAT3 via opioid receptors in hippocampal neurons. Brain Res 2015; 1628:40-9. [PMID: 25839761 DOI: 10.1016/j.brainres.2015.03.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 03/12/2015] [Accepted: 03/20/2015] [Indexed: 01/18/2023]
Abstract
Alterations in glutamate transporter expression are closely related to opiate addition behavior, but the role of opioid receptors is unclear. In this study, we used primary cultures of hippocampal neurons from neonatal rats to study the effects of chronic exposure to morphine on excitatory amino acid transporter 3 (EAAT3) expression and the roles of µ opioid receptor (MOR), δ opioid receptor (DOR), and κ opioid receptor (KOR) in the morphine-dependent alterations in EAAT3 expression. The results showed that the EAAT3 protein and mRNA expression levels decreased significantly after chronic exposure to morphine (10μmol/L) for 48h, whereas the concentration of extracellular glutamate increased. In addition, we found that both the MOR inhibitor CTOP and the DOR inhibitor naltrindole could reverse the decreased expression of EAAT3 after exposure to morphine, whereas the MOR activator DAMGO and the DOR activator DPDPE significantly decreased EAAT3 expression. The KOR inhibitor had no effect on the expression of EAAT3, whereas its activator increased EAAT3 expression. These results suggest that the down-regulation of morphine-dependent EAAT3 expression in primary rat hippocampal cultures may be mediated by MOR and DOR and that KOR may not contribute significantly to this effect.
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Gegelashvili G, Bjerrum OJ. High-affinity glutamate transporters in chronic pain: an emerging therapeutic target. J Neurochem 2014; 131:712-30. [DOI: 10.1111/jnc.12957] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/18/2014] [Accepted: 09/25/2014] [Indexed: 01/13/2023]
Affiliation(s)
- Georgi Gegelashvili
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
- Institute of Chemical Biology; Ilia State University; Tbilisi Georgia
| | - Ole J. Bjerrum
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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Bianchi MG, Bardelli D, Chiu M, Bussolati O. Changes in the expression of the glutamate transporter EAAT3/EAAC1 in health and disease. Cell Mol Life Sci 2014; 71:2001-15. [PMID: 24162932 PMCID: PMC11113519 DOI: 10.1007/s00018-013-1484-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/17/2013] [Accepted: 09/19/2013] [Indexed: 12/14/2022]
Abstract
Excitatory amino acid transporters (EAATs) are high-affinity Na(+)-dependent carriers of major importance in maintaining glutamate homeostasis in the central nervous system. EAAT3, the human counterpart of the rodent excitatory amino acid carrier 1 (EAAC1), is encoded by the SLC1A1 gene. EAAT3/EAAC1 is ubiquitously expressed in the brain, mostly in neurons but also in other cell types, such as oligodendrocyte precursors. While most of the glutamate released in the synapses is taken up by the "glial-type" EAATs, EAAT2 (GLT-1 in rodents) and EAAT1 (GLAST), the functional role of EAAT3/EAAC1 is related to the subtle regulation of glutamatergic transmission. Moreover, because it can also transport cysteine, EAAT3/EAAC1 is believed to be important for the synthesis of intracellular glutathione and subsequent protection from oxidative stress. In contrast to other EAATs, EAAT3/EAAC1 is mostly intracellular, and several mechanisms have been described for the rapid regulation of the membrane trafficking of the transporter. Moreover, the carrier interacts with several proteins, and this interaction modulates transport activity. Much less is known about the slow regulatory mechanisms acting on the expression of the transporter, although several recent reports have identified changes in EAAT3/EAAC1 protein level and activity related to modulation of its expression at the gene level. Moreover, EAAT3/EAAC1 expression is altered in pathological conditions, such as hypoxia/ischemia, multiple sclerosis, schizophrenia, and epilepsy. This review summarizes these results and provides an overall picture of changes in EAAT3/EAAC1 expression in health and disease.
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Affiliation(s)
- Massimiliano G. Bianchi
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
- Unit of Occupational Medicine, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Donatella Bardelli
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
| | - Martina Chiu
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
| | - Ovidio Bussolati
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
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10
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Wu Q, Xia S, Lin J, Cao D, Chen W, Liu L, Fu Y, Liang J, Cao M. Effects of the altered activity of δ-opioid receptor on the expression of glutamate transporter type 3 induced by chronic exposure to morphine. J Neurol Sci 2013; 335:174-81. [PMID: 24120272 DOI: 10.1016/j.jns.2013.09.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 11/29/2022]
Abstract
Altered δ-opioid receptor (DOR) activity can affect the activity and function of excitatory amino acid transporter 3 (EAAT3), but the effects of DOR on EAAT3 expression in morphine relapse remain unknown. In this study, a C6δ cell line and SD rats in a conditioned place preference (CPP) reinstatement model were used. Here, we show that EAAT3 protein levels in C6δ cells decreased significantly after chronic exposure to morphine (10 μM) for 48 h and returned to normal 12 h after drug withdrawal. When C6δ cells were re-exposed to 5 μM morphine for 4 h, EAAT3 protein levels again decreased significantly. The selective μ opioid receptor (MOR) specific agonist DAMGO had a similar effect as morphine, and CTOP, a specific MOR blocker, reversed the declined expression of EAAT3 protein triggered by morphine exposure. The selective DOR agonist [d-pen2, 5] enkephalin (DPDPE) significantly increased EAAT3 expression in C6δ cells and even reversed the decreased EAAT3 expression caused by chronic morphine exposure. The non specific antagonist naloxone, but not the DOR inhibitor Naltrindole (NTI), reversed the decreased EAAT3 expression in C6δ cells caused by chronic morphine exposure. In vivo, EAAT3 levels in the prefrontal cortex of rats with morphine-induced CPP reinstatement significantly decreased. Naloxone completely suppressed reinstatement and reversed the decrease in EAAT3 expression induced by morphine re-exposure. In contrast, NTI only weakened CPP reinstatement and exerted no influence on EAAT3 expression. These findings suggest that DOR can affect the expression of EAAT3. However, the morphine-induced down-regulation of EAAT3 in C6δ cells and in the prefrontal cortex of rats may not be mediated by DOR.
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Affiliation(s)
- Qiang Wu
- Department of Anesthesiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, Guangdong, PR China
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Son I, Shin HJ, Ryu JH, Kim HK, Do SH, Zuo Z. Progesterone increases the activity of glutamate transporter type 3 expressed in Xenopus oocytes. Eur J Pharmacol 2013; 715:414-9. [PMID: 23602688 DOI: 10.1016/j.ejphar.2013.03.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/25/2013] [Accepted: 03/28/2013] [Indexed: 11/15/2022]
Abstract
Progesterone is an important sex hormone for pregnancy and also has neuroprotective and anticonvulsant effects. It is well-known that full-term parturients become more susceptible to volatile anesthetics. Glutamate transporters are important for preventing neurotoxicity and anesthetic action in the central nervous system. We investigated the effects of progesterone on the activity of glutamate transporter type 3 (EAAT3), the major neuronal EAAT. EAAT3 was expressed in Xenopus laevis oocytes by injecting its mRNA. Oocytes were incubated with diluted progesterone for 72 h. Two-electrode voltage clamping was used to measure membrane currents before, during, and after applying 30 μML-glutamate. Progesterone (1-100 nM) significantly increased EAAT3 activity in a dose-dependent manner. Our kinetic study showed that the Vmax was increased in the progesterone group compared with that in the control group (2.7 ± 0.2 vs. 3.6 ± 0.2μC for control group vs. progesterone group; n=18-23; P<0.05), however, Km was unaltered (46.7 ± 10.2μM vs. 55.9 ± 10.5μM for control group vs. progesterone group; n=18-23; P>0.05). Phorbol-12-myristate-13-acetate, a protein kinase C (PKC) activator, did not change progesterone-enhanced EAAT3 activity. Inhibitors of PKC or phosphatidylinositol 3-kinase (PI3K) abolished the progesterone-induced increases in EAAT3 activity. Our results suggest that progesterone enhances EAAT3 activity and that PKC and PI3K are involved in mediating these effects. These effects of progesterone may contribute to its anticonvulsant and anesthesia-related properties.
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Affiliation(s)
- Ilsoon Son
- Department of Anesthesiology & Pain Medicine, Konkuk University School of Medicine, Seoul, South Korea
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Neuroprotective properties of the excitatory amino acid carrier 1 (EAAC1). Amino Acids 2013; 45:133-42. [PMID: 23462929 DOI: 10.1007/s00726-013-1481-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/23/2013] [Indexed: 01/09/2023]
Abstract
Extracellular glutamate should be maintained at low levels to conserve optimal neurotransmission and prevent glutamate neurotoxicity in the brain. Excitatory amino acid transporters (EAATs) play a pivotal role in removing extracellular glutamate in the central nervous system (CNS). Excitatory amino acid carrier 1 (EAAC1) is a high-affinity Na⁺-dependent neuronal EAAT that is ubiquitously expressed in the brain. However, most glutamate released in the synapses is cleared by glial EAATs, but not by EAAC1 in vivo. In the CNS, EAAC1 is widely distributed in somata and dendrites but not in synaptic terminals. The contribution of EAAC1 to the control of extracellular glutamate levels seems to be negligible in the brain. However, EAAC1 can transport not only extracellular glutamate but also cysteine into the neurons. Cysteine is an important substrate for glutathione (GSH) synthesis in the brain. GSH has a variety of neuroprotective functions, while its depletion induces neurodegeneration. Therefore, EAAC1 might exert a critical role for neuroprotection in neuronal GSH metabolism rather than glutamatergic neurotransmission, while EAAC1 dysfunction would cause neurodegeneration. Despite the potential importance of EAAC1 in the brain, previous studies have mainly focused on the glutamate neurotoxicity induced by glial EAAT dysfunction. In recent years, however, several studies have revealed regulatory mechanisms of EAAC1 functions in the brain. This review will summarize the latest information on the EAAC1-regulated neuroprotective functions in the CNS.
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Inhibition of Activity of GABA Transporter GAT1 by δ-Opioid Receptor. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:818451. [PMID: 23365600 PMCID: PMC3543822 DOI: 10.1155/2012/818451] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/04/2012] [Accepted: 11/04/2012] [Indexed: 01/16/2023]
Abstract
Analgesia is a well-documented effect of acupuncture. A critical role in pain sensation plays the nervous system, including the GABAergic system and opioid receptor (OR) activation. Here we investigated regulation of GABA transporter GAT1 by δOR in rats and in Xenopus oocytes. Synaptosomes of brain from rats chronically exposed to opiates exhibited reduced GABA uptake, indicating that GABA transport might be regulated by opioid receptors. For further investigation we have expressed GAT1 of mouse brain together with mouse δOR and μOR in Xenopus oocytes. The function of GAT1 was analyzed in terms of Na+-dependent [3H]GABA uptake as well as GAT1-mediated currents. Coexpression of δOR led to reduced number of fully functional GAT1 transporters, reduced substrate translocation, and GAT1-mediated current. Activation of δOR further reduced the rate of GABA uptake as well as GAT1-mediated current. Coexpression of μOR, as well as μOR activation, affected neither the number of transporters, nor rate of GABA uptake, nor GAT1-mediated current. Inhibition of GAT1-mediated current by activation of δOR was confirmed in whole-cell patch-clamp experiments on rat brain slices of periaqueductal gray. We conclude that inhibition of GAT1 function will strengthen the inhibitory action of the GABAergic system and hence may contribute to acupuncture-induced analgesia.
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Aoyama K, Watabe M, Nakaki T. Modulation of neuronal glutathione synthesis by EAAC1 and its interacting protein GTRAP3-18. Amino Acids 2011; 42:163-9. [PMID: 21373771 DOI: 10.1007/s00726-011-0861-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 01/17/2023]
Abstract
Glutathione (GSH) plays essential roles in different processes such as antioxidant defenses, cell signaling, cell proliferation, and apoptosis in the central nervous system. GSH is a tripeptide composed of glutamate, cysteine, and glycine. The concentration of cysteine in neurons is much lower than that of glutamate or glycine, so that cysteine is the rate-limiting substrate for neuronal GSH synthesis. Most neuronal cysteine uptake is mediated through the neuronal sodium-dependent glutamate transporter, known as excitatory amino acid carrier 1 (EAAC1). Glutamate transporters are vulnerable to oxidative stress and EAAC1 dysfunction impairs neuronal GSH synthesis by reducing cysteine uptake. This may start a vicious circle leading to neurodegeneration. Intracellular signaling molecules functionally regulate EAAC1. Glutamate transporter-associated protein 3-18 (GTRAP3-18) activation down-regulates EAAC1 function. Here, we focused on the interaction between EAAC1 and GTRAP3-18 at the plasma membrane to investigate their effects on neuronal GSH synthesis. Increased level of GTRAP3-18 protein induced a decrease in GSH level and, thereby, increased the vulnerability to oxidative stress, while decreased level of GTRAP3-18 protein induced an increase in GSH level in vitro. We also confirmed these results in vivo. Our studies demonstrate that GTRAP3-18 regulates neuronal GSH level by controlling the EAAC1-mediated uptake of cysteine.
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Affiliation(s)
- Koji Aoyama
- Department of Pharmacology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo, 173-8605, Japan
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Deng H, Yang Z, Li Y, Bao G, Friedrich T, Gu Q, Shen X, Schwarz W. Interactions of Na+,K+-ATPase and co-expressed delta-opioid receptor. Neurosci Res 2009; 65:222-7. [PMID: 19619588 DOI: 10.1016/j.neures.2009.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 06/16/2009] [Accepted: 07/10/2009] [Indexed: 11/24/2022]
Abstract
To investigate interference of delta-opioid receptor with the Na(+),K(+)-ATPase in a simple model system, we used the Xenopus oocytes as an expression system. Our results indicate that expression of the delta-opioid receptor (DOR) results in reduction of endogenous sodium-pump activity. Stimulation of DOR by the DOR agonist [(D)-Pen(2,5)]-enkephalin (DPDPE) had no pronounced additional effect on pump activity. Qualitatively similar results were obtained in experiments with a variety of co-expressed exogenous sodium pumps. We suggest that reduced pump activity with DOR expression is brought about by an interaction of the pump with DOR. Direct interaction is also supported by co-immunoprecipitation, not only in the Xenopus oocytes but also in rat hippocampal neurons. The interaction may be responsible for altered agonist sensitivity of DOR; activation of the sodium pump led to an increase of the K(m) value for DOR activation by DPDPE from about 0.17 to 0.27muM. In conclusion, pump activity not only affects neural activity directly but our results also suggest that pump activity is affected through functional interaction with DOR that will modulate pain sensation.
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Affiliation(s)
- Haiping Deng
- Shanghai Research Center for Acupuncture and Meridians, China
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16
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Abstract
The brain is among the major organs generating large amounts of reactive oxygen species and is especially susceptible to oxidative stress. Glutathione (GSH) plays critical roles as an antioxidant, enzyme cofactor, cysteine storage form, the major redox buffer, and a neuromodulator in the central nervous system. GSH deficiency has been implicated in neurodegenerative diseases. GSH is a tripeptide comprised of glutamate, cysteine, and glycine. Cysteine is the rate-limiting substrate for GSH synthesis within neurons. Most neuronal cysteine uptake is mediated by sodium-dependent excitatory amino acid transporter (EAAT) systems, known as excitatory amino acid carrier 1 (EAAC1). Previous studies demonstrated EAAT is vulnerable to oxidative stress, leading to impaired function. A recent study found EAAC1-deficient mice to have decreased brain GSH levels and increased susceptibility to oxidative stress. The function of EAAC1 is also regulated by glutamate transporter associated protein 3-18. This review focuses on the mechanisms underlying GSH synthesis, especially those related to neuronal cysteine transport via EAAC1, as well as on the importance of GSH functions against oxidative stress.
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Affiliation(s)
- Koji Aoyama
- Department of Pharmacology, Teikyo University School of Medicine, Itabashi, Tokyo, Japan
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Yang ZJ, Bao GB, Deng HP, Du HM, Gu QB, Pei G, Pu L, Schwarz W, Xia P. Interaction of δ-opioid receptor with membrane transporters: Possible mechanisms in pain suppression by acupuncture. JOURNAL OF ACUPUNCTURE AND TUINA SCIENCE 2008. [DOI: 10.1007/s11726-008-0298-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chao D, Bazzy-Asaad A, Balboni G, Salvadori S, Xia Y. Activation of DOR attenuates anoxic K+ derangement via inhibition of Na+ entry in mouse cortex. Cereb Cortex 2008; 18:2217-27. [PMID: 18203692 DOI: 10.1093/cercor/bhm247] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We have recently found that in the mouse cortex, activation of delta-opioid receptor (DOR) attenuates the disruption of K(+) homeostasis induced by hypoxia or oxygen-glucose deprivation. This novel observation suggests that DOR may protect neurons from hypoxic/ischemic insults via the regulation of K(+) homeostasis because the disruption of K(+) homeostasis plays a critical role in neuronal injury under hypoxic/ischemic stress. The present study was performed to explore the ionic mechanism underlying the DOR-induced neuroprotection. Because anoxia causes Na(+) influx and thus stimulates K(+) leakage, we investigated whether DOR protects the cortex from anoxic K(+) derangement by targeting the Na(+)-based K(+) leakage. By using K(+)-sensitive microelectrodes in mouse cortical slices, we showed that 1) lowering Na(+) concentration and substituting with impermeable N-methyl-D-glucamine caused a concentration-dependent attenuation of anoxic K(+) derangement; 2) lowering Na(+) concentration by substituting with permeable Li(+) tended to potentiate the anoxic K(+) derangement; and 3) the DOR-induced protection against the anoxic K(+) responses was largely abolished by low-Na(+) perfusion irrespective of the substituted cation. We conclude that external Na(+) concentration greatly influences anoxic K(+) derangement and that DOR activation likely attenuates anoxic K(+) derangement induced by the Na(+)-activated mechanisms in the cortex.
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Affiliation(s)
- Dongman Chao
- Department of Pediatrics, Section of Respiratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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Loacker S, Sayyah M, Wittmann W, Herzog H, Schwarzer C. Endogenous dynorphin in epileptogenesis and epilepsy: anticonvulsant net effect via kappa opioid receptors. ACTA ACUST UNITED AC 2007; 130:1017-28. [PMID: 17347252 DOI: 10.1093/brain/awl384] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neuropsychiatric disorders are one of the main challenges of human medicine with epilepsy being one of the most common serious disorders of the brain. Increasing evidence suggest neuropeptides, particularly the opioids, play an important role in epilepsy. However, little is known about the mechanisms of the endogenous opioid system in epileptogenesis and epilepsy. Therefore, we investigated the role of endogenous prodynorphin-derived peptides in epileptogenesis, acute seizure behaviour and epilepsy in prodynorphin-deficient mice. Compared with wild-type littermates, prodynorphin knockout mice displayed a significantly reduced seizure threshold as assessed by tail-vein infusion of the GABA(A) antagonist pentylenetetrazole. This phenotype could be entirely rescued by the kappa receptor-specific agonist U-50488, but not by the mu receptor-specific agonist DAMGO. The delta-specific agonist SNC80 decreased seizure threshold in both genotypes, wild-type and knockout. Pre-treatment with the kappa selective antagonist GNTI completely blocked the rescue effect of U-50488. Consistent with the reduced seizure threshold, prodynorphin knockout mice showed faster seizure onset and a prolonged time of seizure activity after intracisternal injection of kainic acid. Three weeks after local injection of kainic acid into the stratum radiatum CA1 of the dorsal hippocampus, prodynorphin knockout mice displayed an increased extent of granule cell layer dispersion and neuronal loss along the rostrocaudal axis of the ipsi- and partially also of the contralateral hippocampus. In the classical pentylenetetrazole kindling model, dynorphin-deficient mice showed significantly faster kindling progression with six out of eight animals displaying clonic seizures, while none of the nine wild-types exceeded rating 3 (forelimb clonus). Taken together, our data strongly support a critical role for dynorphin in the regulation of hippocampal excitability, indicating an anticonvulsant role of kappa opioid receptors, thereby providing a potential target for antiepileptic drugs.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics/pharmacology
- Animals
- Benzamides/pharmacology
- Cell Count
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalins/genetics
- Enkephalins/metabolism
- Enkephalins/physiology
- Epilepsy, Temporal Lobe/metabolism
- Epilepsy, Temporal Lobe/physiopathology
- Guanidines
- Hippocampus/metabolism
- Kindling, Neurologic/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Morphinans
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Nerve Degeneration/metabolism
- Piperazines/pharmacology
- Protein Precursors/genetics
- Protein Precursors/metabolism
- Protein Precursors/physiology
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/physiology
- Synaptic Transmission/physiology
- Time Factors
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Affiliation(s)
- Stephan Loacker
- Department of Pharmacology, Innsbruck Medical University, Innsbruck, Austria
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