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Liu X, Yu J, Tan X, Zhang Q, Niu J, Hou Z, Wang Q. Necroptosis involved in sevoflurane-induced cognitive dysfunction in aged mice by activating NMDA receptors increasing intracellular calcium. Neurotoxicology 2024; 100:35-46. [PMID: 38070654 DOI: 10.1016/j.neuro.2023.12.006] [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: 10/09/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 01/17/2024]
Abstract
Perioperative neurocognitive disorders are a common surgical and postanesthesia complication. Necroptosis contributes to the emergence of various neurological disorders. We conjecture that cognitive impairment is associated with necroptosis of hippocampal neurons, which is mediated by NMDA receptors leading to cytoplasmic calcium imbalance. C57BL/6 J male mice ( 18 months) were randomly divided into the C ( control group), S ( sevoflurane group), S+M ( sevoflurane plus the NMDA receptor antagonist memantine group) and S+N ( sevoflurane plus necrostatin-1) group. We exposed the mice to 3% sevoflurane for 2 h a day for three consecutive days in the S, S+M and S+N groups. Memantine ( 20 mg/kg) or Nec-1 ( 10 mg/kg) was injected intraperitoneally 1 h before sevoflurane anesthesia in the S+M or S+N group. We used the animal behavior tests to evaluate the cognitive function. Pathological damage, the rate of necroptosis, [Ca2+]i, and the expression of necroptosis-related proteins were evaluated. The cognitive function tests, pathological damage, the rate of necroptosis, the expression of necroptosis-related proteins, NMDAR2A and NMDAR2B were significantly different in the S group ( P < 0.05). Alleviated pathological damage, decreased the rate of necroptosis and down-regulated the expression of necroptosis-related proteins occurred in the S+M and S+N group ( P < 0.05). The lower elevated [Ca2+]i, expression of NMDAR2A and NMDAR2B were found in the S+M group. Our findings highlighted sevoflurane-induced cognitive dysfunction is associated with an imbalance in cytoplasmic calcium homeostasis by activating NMDA receptors, which causes hippocampus neurons to undergo necroptosis and ultimately affects cognitive performance in aged mice.
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Affiliation(s)
- Xiang Liu
- Department of Anesthesiology, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China; Department of Anesthesiology, Children's Hospital of Hebei Province, Shijiazhuang 050030, China
| | - Jiaxu Yu
- Department of Anesthesiology, Cang Zhou Centrol Hospital, Cangzhou 061017, Hebei, China
| | - Xiaona Tan
- Department of Neurological Rehabilitation, Children's Hospital of Hebei Province, Shijiazhuang 050030, China
| | - Qi Zhang
- Department of Anesthesiology, Children's Hospital of Hebei Province, Shijiazhuang 050030, China
| | - Junfang Niu
- Department of Anesthesiology, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China
| | - Zhiyong Hou
- Center of Emergency and Trauma, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China
| | - Qiujun Wang
- Department of Anesthesiology, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China.
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Johnson LR, Battle AR, Martinac B. Remembering Mechanosensitivity of NMDA Receptors. Front Cell Neurosci 2019; 13:533. [PMID: 31866826 PMCID: PMC6906178 DOI: 10.3389/fncel.2019.00533] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/18/2019] [Indexed: 12/14/2022] Open
Abstract
An increase in post-synaptic Ca2+ conductance through activation of the ionotropic N-methyl-D-aspartate receptor (NMDAR) and concomitant structural changes are essential for the initiation of long-term potentiation (LTP) and memory formation. Memories can be initiated by coincident events, as occurs in classical conditioning, where the NMDAR can act as a molecular coincidence detector. Binding of glutamate and glycine, together with depolarization of the postsynaptic cell membrane to remove the Mg2+ channel pore block, results in NMDAR opening for Ca2+ conductance. Accumulating evidence has implicated both force-from-lipids and protein tethering mechanisms for mechanosensory transduction in NMDAR, which has been demonstrated by both, membrane stretch and application of amphipathic molecules such as arachidonic acid (AA). The contribution of mechanosensitivity to memory formation and consolidation may be to increase activity of the NMDAR leading to facilitated memory formation. In this review we look back at the progress made toward understanding the physiological and pathological role of NMDA receptor channels in mechanobiology of the nervous system and consider these findings in like of their potential functional implications for memory formation. We examine recent studies identifying mechanisms of both NMDAR and other mechanosensitive channels and discuss functional implications including gain control of NMDA opening probability. Mechanobiology is a rapidly growing area of biology with many important implications for understanding form, function and pathology in the nervous system.
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Affiliation(s)
- Luke R Johnson
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia.,Division of Psychology, School of Medicine, University of Tasmania, Launceston, TAS, Australia.,Department of Psychiatry, Center for the Study of Traumatic Stress, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.,School of Biomedical Sciences, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, QLD, Australia
| | - Andrew R Battle
- School of Biomedical Sciences, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, QLD, Australia.,Prince Charles Hospital Northside Clinical Unit, School of Clinical Medicine, The University of Queensland, Brisbane, QLD, Australia.,Translational Research Institute, Woolloongabba, QLD, Australia
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
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Jerusalem A, Al-Rekabi Z, Chen H, Ercole A, Malboubi M, Tamayo-Elizalde M, Verhagen L, Contera S. Electrophysiological-mechanical coupling in the neuronal membrane and its role in ultrasound neuromodulation and general anaesthesia. Acta Biomater 2019; 97:116-140. [PMID: 31357005 DOI: 10.1016/j.actbio.2019.07.041] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 01/23/2023]
Abstract
The current understanding of the role of the cell membrane is in a state of flux. Recent experiments show that conventional models, considering only electrophysiological properties of a passive membrane, are incomplete. The neuronal membrane is an active structure with mechanical properties that modulate electrophysiology. Protein transport, lipid bilayer phase, membrane pressure and stiffness can all influence membrane capacitance and action potential propagation. A mounting body of evidence indicates that neuronal mechanics and electrophysiology are coupled, and together shape the membrane potential in tight coordination with other physical properties. In this review, we summarise recent updates concerning electrophysiological-mechanical coupling in neuronal function. In particular, we aim at making the link with two relevant yet often disconnected fields with strong clinical potential: the use of mechanical vibrations-ultrasound-to alter the electrophysiogical state of neurons, e.g., in neuromodulation, and the theories attempting to explain the action of general anaesthetics. STATEMENT OF SIGNIFICANCE: General anaesthetics revolutionised medical practice; now an apparently unrelated technique, ultrasound neuromodulation-aimed at controlling neuronal activity by means of ultrasound-is poised to achieve a similar level of impact. While both technologies are known to alter the electrophysiology of neurons, the way they achieve it is still largely unknown. In this review, we argue that in order to explain their mechanisms/effects, the neuronal membrane must be considered as a coupled mechano-electrophysiological system that consists of multiple physical processes occurring concurrently and collaboratively, as opposed to sequentially and independently. In this framework the behaviour of the cell membrane is not the result of stereotypical mechanisms in isolation but instead emerges from the integrative behaviour of a complexly coupled multiphysics system.
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Affiliation(s)
- Antoine Jerusalem
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
| | - Zeinab Al-Rekabi
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Haoyu Chen
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Ari Ercole
- Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Majid Malboubi
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Miren Tamayo-Elizalde
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Lennart Verhagen
- Wellcome Centre for Integrative Neuroimaging (WIN), Department of Experimental Psychology, University of Oxford, Oxford OX1 3TA, UK; WIN, Centre for Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Sonia Contera
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
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Potassium channels-mediated electrophysiologic responses are inhibited by cytosolic phospholipase A2α ablation. Neuroreport 2018; 29:59-64. [PMID: 29112675 DOI: 10.1097/wnr.0000000000000933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cytosolic phospholipase A2α (cPLA2α) is implicated in the progression of excitotoxic neuronal injury and cerebral ischemia. Previous work suggests that cPLA2α increases aberrant electrophysiologic events through attenuating K channel functions. Nevertheless, which K channels are affected by cPLA2α needs to be determined. Here we examined K channels-mediated electrophysiologic responses in hippocampal CA1 pyramidal neurons from wild-type and cPLA2α mice using simultaneous patch-clamp recording and confocal Ca imaging. After the exposure to the blockers of Ca-sensitive and A-type K channels, all CA1 neurons developed spike broadening and increased dendritic Ca transients. These effects were occluded in CA1 neurons from cPLA2α mice. Therefore, cPLA2α modulates the functions of Ca-sensitive and A-type K channels in neurotoxicity.
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Chung YC, Cui Y, Sumiyoshi T, Kim MG, Lee KH. Associations of fatty acids with cognition, psychopathology, and brain-derived neurotrophic factor levels in patients with first-episode schizophrenia and related disorders treated with paliperidone extended release. J Psychopharmacol 2017; 31:1556-1563. [PMID: 28946784 DOI: 10.1177/0269881117731169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This study assessed fatty acid and brain-derived neurotrophic factor levels in patients with first-episode schizophrenia and related disorders. The levels of erythrocyte fatty acids and plasma brain-derived neurotrophic factor were measured at baseline and week 8 after treatment with paliperidone extended release. Cognitive function was evaluated using the Cognitive Assessment Interview and the cognition subscale of the Neuroleptic-Induced Deficit Syndrome Scale. There were significant decreases in stearic acid and nervonic acid levels and a significant increase in eicosapentaenoic acid levels after eight weeks. At week 8, cognition was positively associated with dihomo-γ-linolenic acid, linoleic acid, and eicosapentaenoic acid levels, and negatively associated with nervonic acid levels. Psychopathology was positively correlated with polyunsaturated fatty acid levels, and negatively correlated with saturated fatty acid levels at week 8. At both baseline and week 8, brain-derived neurotrophic factor level had a negative association with polyunsaturated fatty acids and a positive association with saturated fatty acids and monounsaturated fatty acids. The present study demonstrated that fatty acids have significant associations with cognition and psychopathology at week 8, and with brain-derived neurotrophic factor levels at both baseline and week 8.
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Affiliation(s)
- Young-Chul Chung
- 1 Department of Psychiatry, Chonbuk National University Hospital, Jeonju, Korea.,4 Department of Psychiatry, Chonbuk National University Medical School, Jeonju, Korea
| | - Yin Cui
- 2 Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, Korea.,4 Department of Psychiatry, Chonbuk National University Medical School, Jeonju, Korea
| | - Tomiki Sumiyoshi
- 5 Department of Clinical Epidemiology, Translational Medical Center, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Min-Gul Kim
- 6 Clinical Pharmacology Unit, Chonbuk National University Hospital, Jeonju, Korea.,7 Biomedical Research Institute, Chonbuk National University Hospital, Jeonju, Korea
| | - Keon-Hak Lee
- 8 Department of Psychiatry, Maeumsarang Hospital, Wanju, Korea
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Sheppard KW, Cheatham CL. Executive functions and the ω-6-to-ω-3 fatty acid ratio: a cross-sectional study. Am J Clin Nutr 2017; 105:32-41. [PMID: 27852615 PMCID: PMC5183732 DOI: 10.3945/ajcn.116.141390] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 10/18/2016] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND The ω-6 (n-6) to ω-3 (n-3) fatty acid (FA) ratio (n-6:n-3 ratio) was previously shown to be a predictor of executive function performance in children aged 7-9 y. OBJECTIVE We aimed to replicate and extend previous findings by exploring the role of the n-6:n-3 ratio in executive function performance. We hypothesized that there would be an interaction between n-3 and the n-6:n-3 ratio, with children with low n-3 performing best with a low ratio, and those with high n-3 performing best with a high ratio. DESIGN Children were recruited on the basis of their consumption of n-6 and n-3 FAs. The executive function performance of 78 children aged 7-12 y was tested with the use of the Cambridge Neuropsychological Test Automated Battery and a planning task. Participants provided blood for plasma FA quantification, and the caregiver completed demographic and activity questionnaires. We investigated the role of the n-6:n-3 ratio in the entire sample and separately in children aged 7-9 y (n = 41) and 10-12 y (n = 37). RESULTS Dietary and plasma n-6:n-3 ratio and n-3 predicted performance on working memory and planning tasks in children 7-12 y old. The interaction between dietary n-6:n-3 ratio and n-3 predicted the number of moves required to solve the most difficult planning problems in children aged 7-9 y and those aged 10-12 y, similar to results from the previous study. There was also an interaction between the plasma n-6:n-3 ratio and n-3 predicting time spent thinking through the difficult 5-move planning problems. The n-6:n-3 ratio and n-3 predicted executive function performance differently in children aged 7-9 y and in those aged 10-12 y, indicating different optimal FA balances across development. CONCLUSIONS The n-6:n-3 ratio is an important consideration in the role of FAs in cognitive function, and the optimal balance of n-6 and n-3 FAs depends on the cognitive function and developmental period studied. This trial was registered at clinicaltrials.gov as NCT02199808.
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Affiliation(s)
- Kelly W Sheppard
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC;,Center for Biobehavioral Health, The Research Institute at Nationwide Children’s Hospital, Columbus, OH; and
| | - Carol L Cheatham
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC; .,Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC
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Abstract
This paper examines current knowledge about putative "pro-algesic" dietary components, and discusses whether limiting the intake of these substances can help improve chronic pain. Although there is a common impression that numerous food components, natural and synthetic, can cause or worsen pain symptoms, very few of these substances have been investigated. This article focuses on four substances, monosodium glutamate, aspartame, arachidonic acid, and caffeine, where research shows that overconsumption may induce or worsen pain. For each substance, the mechanism whereby it may act to induce pain is examined, and any clinical trials examining the effectiveness of reducing the intake of the substance discussed. While all four substances are associated with pain, decreased consumption of them does not consistently reduce pain.
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Affiliation(s)
- Brian Edwin Cairns
- a Faculty of Pharmaceutical Sciences , The University of British Columbia , Vancouver , Canada.,b Center for Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Faculty of Medicine , Aalborg University , Aalborg East , Denmark
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8
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Sheppard KW, Cheatham CL. Omega-6 to omega-3 fatty acid ratio and higher-order cognitive functions in 7- to 9-y-olds: a cross-sectional study. Am J Clin Nutr 2013; 98:659-67. [PMID: 23824723 DOI: 10.3945/ajcn.113.058719] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Biochemical and behavioral evidence has suggested that the ratio of n-6 (omega-6) to n-3 (omega-3) could be an important predictor of executive function abilities in children. OBJECTIVE We determined the relation between the ratio of n-6 to n-3 and cognitive function in children. We hypothesized that children with lower ratios of n-6 to n-3 fatty acids would perform better on tests of planning and working memory. DESIGN Seventy 7- to 9-y-old children completed three 24-h diet recalls and a subset of the Cambridge Neuropsychological Test Assessment Battery. Parents provided information on their demographics and children's diet histories. RESULTS Mean n-3 and mean n-6 intakes were related to the mean time spent on each action taken in the planning problem. The ratio of n-6 to n-3 significantly predicted performance on the working memory and planning problems. There was a significant interaction between the ratio and fatty acid intake; when children had high ratios, a higher intake of n-3 fatty acids predicted a better performance on the planning task than when children had lower n-3 intakes. When children had low ratios, a lower intake of n-3 and lower intake of n-6 predicted better performance than when intakes were higher. CONCLUSIONS The relation between cognitive abilities and the ratio of n-6 to n-3 may be mediated by an enzymatic affinity for n-3 fatty acids. The ratio of n-6 to n-3 should be considered an important factor in the study of fatty acids and cognitive development. This trial was registered at clinicaltrials.gov as NCT01823419.
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Affiliation(s)
- Kelly W Sheppard
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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9
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Ramsden CE, Mann JD, Faurot KR, Lynch C, Imam ST, MacIntosh BA, Hibbeln JR, Loewke J, Smith S, Coble R, Suchindran C, Gaylord SA. Low omega-6 vs. low omega-6 plus high omega-3 dietary intervention for chronic daily headache: protocol for a randomized clinical trial. Trials 2011; 12:97. [PMID: 21496264 PMCID: PMC3096579 DOI: 10.1186/1745-6215-12-97] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 04/15/2011] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Targeted analgesic dietary interventions are a promising strategy for alleviating pain and improving quality of life in patients with persistent pain syndromes, such as chronic daily headache (CDH). High intakes of the omega-6 (n-6) polyunsaturated fatty acids (PUFAs), linoleic acid (LA) and arachidonic acid (AA) may promote physical pain by increasing the abundance, and subsequent metabolism, of LA and AA in immune and nervous system tissues. Here we describe methodology for an ongoing randomized clinical trial comparing the metabolic and clinical effects of a low n-6, average n-3 PUFA diet, to the effects of a low n-6 plus high n-3 PUFA diet, in patients with CDH. Our primary aim is to determine if: A) both diets reduce n-6 PUFAs in plasma and erythrocyte lipid pools, compared to baseline; and B) the low n-6 plus high n-3 diet produces a greater decline in n-6 PUFAs, compared to the low n-6 diet alone. Secondary clinical outcomes include headache-specific quality-of-life, and headache frequency and intensity. METHODS Adults meeting the International Classification of Headache Disorders criteria for CDH are included. After a 6-week baseline phase, participants are randomized to a low n-6 diet, or a low n-6 plus high n-3 diet, for 12 weeks. Foods meeting nutrient intake targets are provided for 2 meals and 2 snacks per day. A research dietitian provides intensive dietary counseling at 2-week intervals. Web-based intervention materials complement dietitian advice. Blood and clinical outcome data are collected every 4 weeks. RESULTS Subject recruitment and retention has been excellent; 35 of 40 randomized participants completed the 12-week intervention. Preliminary blinded analysis of composite data from the first 20 participants found significant reductions in erythrocyte n-6 LA, AA and %n-6 in HUFA, and increases in n-3 EPA, DHA and the omega-3 index, indicating adherence. TRIAL REGISTRATION ClinicalTrials.gov (NCT01157208).
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Affiliation(s)
- Christopher E Ramsden
- Section on Nutritional Neurosciences, Laboratory of Membrane Biochemistry and Biophysics, NIAAA, NIH, Bethesda, MD, USA
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - J Douglas Mann
- Department of Neurology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Keturah R Faurot
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chanee Lynch
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Syed Taha Imam
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Beth A MacIntosh
- North Carolina Translational and Clinical Sciences Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joseph R Hibbeln
- Section on Nutritional Neurosciences, Laboratory of Membrane Biochemistry and Biophysics, NIAAA, NIH, Bethesda, MD, USA
| | - James Loewke
- Section on Nutritional Neurosciences, Laboratory of Membrane Biochemistry and Biophysics, NIAAA, NIH, Bethesda, MD, USA
| | - Sunyata Smith
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rebecca Coble
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chirayath Suchindran
- Department of Biostatistics, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Susan A Gaylord
- Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Kishimoto K, Li RC, Zhang J, Klaus JA, Kibler KK, Doré S, Koehler RC, Sapirstein A. Cytosolic phospholipase A2 alpha amplifies early cyclooxygenase-2 expression, oxidative stress and MAP kinase phosphorylation after cerebral ischemia in mice. J Neuroinflammation 2010; 7:42. [PMID: 20673332 PMCID: PMC2923122 DOI: 10.1186/1742-2094-7-42] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 07/30/2010] [Indexed: 02/06/2023] Open
Abstract
Background The enzyme cytosolic phospholipase A2 alpha (cPLA2α) has been implicated in the progression of cerebral injury following ischemia and reperfusion. Previous studies in rodents suggest that cPLA2α enhances delayed injury extension and disruption of the blood brain barrier many hours after reperfusion. In this study we investigated the role of cPLA2α in early ischemic cerebral injury. Methods Middle cerebral artery occlusion (MCAO) was performed on cPLA2α+/+ and cPLA2α-/- mice for 2 hours followed by 0, 2, or 6 hours of reperfusion. The levels of cPLA2α, cyclooxygenase-2, neuronal morphology and reactive oxygen species in the ischemic and contralateral hemispheres were evaluated by light and fluorescent microscopy. PGE2 content was compared between genotypes and hemispheres after MCAO and MCAO and 6 hours reperfusion. Regional cerebral blood flow was measured during MCAO and phosphorylation of relevant MAPKs in brain protein homogenates was measured by Western analysis after 6 hours of reperfusion. Results Neuronal cPLA2α protein increased by 2-fold immediately after MCAO and returned to pre-MCAO levels after 2 hours reperfusion. Neuronal cyclooxygenase-2 induction and PGE2 concentration were greater in cPLA2α+/+ compared to cPLA2α-/- ischemic cortex. Neuronal swelling in ischemic regions was significantly greater in the cPLA2α+/+ than in cPLA2α-/- brains (+/+: 2.2 ± 0.3 fold vs. -/-: 1.7 ± 0.4 fold increase; P < 0.01). The increase in reactive oxygen species following 2 hours of ischemia was also significantly greater in the cPLA2α+/+ ischemic core than in cPLA2α-/- (+/+: 7.12 ± 1.2 fold vs. -/-: 3.1 ± 1.4 fold; P < 0.01). After 6 hours of reperfusion ischemic cortex of cPLA2α+/+, but not cPLA2α-/-, had disruption of neuron morphology and decreased PGE2 content. Phosphorylation of the MAPKs-p38, ERK 1/2, and MEK 1/2-was significantly greater in cPLA2a+/+ than in cPLA2α-/- ischemic cortex 6 hours after reperfusion. Conclusions These results indicate that cPLA2α modulates the earliest molecular and injury responses after cerebral ischemia and have implications for the potential clinical use of cPLA2α inhibitors.
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Affiliation(s)
- Koji Kishimoto
- The Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Kemmerling U, Muñoz P, Müller M, Sánchez G, Aylwin ML, Klann E, Carrasco MA, Hidalgo C. Calcium release by ryanodine receptors mediates hydrogen peroxide-induced activation of ERK and CREB phosphorylation in N2a cells and hippocampal neurons. Cell Calcium 2007; 41:491-502. [PMID: 17074386 DOI: 10.1016/j.ceca.2006.10.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 09/21/2006] [Accepted: 10/02/2006] [Indexed: 11/20/2022]
Abstract
Hydrogen peroxide, which stimulates ERK phosphorylation and synaptic plasticity in hippocampal neurons, has also been shown to stimulate calcium release in muscle cells by promoting ryanodine receptor redox modification (S-glutathionylation). We report here that exposure of N2a cells or rat hippocampal neurons in culture to 200 microM H2O2 elicited calcium signals, increased ryanodine receptor S-glutathionylation, and enhanced both ERK and CREB phosphorylation. In mouse hippocampal slices, H2O2 (1 microM) also stimulated ERK and CREB phosphorylation. Preincubation with ryanodine (50 microM) largely prevented the effects of H2O2 on calcium signals and ERK/CREB phosphorylation. In N2a cells, the ERK kinase inhibitor U0126 suppressed ERK phosphorylation and abolished the stimulation of CREB phosphorylation produced by H2O2, suggesting that H2O2 enhanced CREB phosphorylation via ERK activation. In N2a cells in calcium-free media, 200 microM H2O2 stimulated ERK and CREB phosphorylation, while preincubation with thapsigargin prevented these enhancements. These combined results strongly suggest that H2O2 promotes ryanodine receptors redox modification; the resulting calcium release signals, by enhancing ERK activity, would increase CREB phosphorylation. We propose that ryanodine receptor stimulation by activity-generated redox species produces calcium release signals that may contribute significantly to hippocampal synaptic plasticity, including plasticity that requires long-lasting ERK-dependent CREB phosphorylation.
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Affiliation(s)
- Ulrike Kemmerling
- Centro FONDAP de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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12
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Shen Y, Kishimoto K, Linden DJ, Sapirstein A. Cytosolic phospholipase A(2) alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment. Proc Natl Acad Sci U S A 2007; 104:6078-83. [PMID: 17389392 PMCID: PMC1851619 DOI: 10.1073/pnas.0605427104] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Indexed: 11/18/2022] Open
Abstract
The arachidonic acid-generating enzyme cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA(2)alpha toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca(2+) imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA(2)alpha null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA(2)alpha null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca(2+) transient. These effects were absent in CA1 neurons from cPLA(2)alpha null mice and WT neurons treated with a cPLA(2)alpha inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca(2+) enhancement in WT and cPLA(2)alpha null slices. NMDA application in WT and arachidonate applied to cPLA(2)alpha null cells occluded the effects of apamin/paxilline. These results indicate that cPLA(2)alpha activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.
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Affiliation(s)
- Ying Shen
- *Department of Neuroscience
- Department of Neurobiology, Neuroscience Institute, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Koji Kishimoto
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287; and
| | | | - Adam Sapirstein
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287; and
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13
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Brady KM, Texel SJ, Kishimoto K, Koehler RC, Sapirstein A. Cytosolic phospholipase A alpha modulates NMDA neurotoxicity in mouse hippocampal cultures. Eur J Neurosci 2007; 24:3381-6. [PMID: 17229087 DOI: 10.1111/j.1460-9568.2006.05237.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The arachidonic acid-specific cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the generation of neurological injuries. cPLA(2)alpha-dependent neurological injury has been postulated to be mediated through inflammatory and eicosanoid pathways. We determined if cPLA(2)alpha amplifies the injury of a non-inflammatory, excitotoxic stimulus by modifying a well-described toxicity assay to measure the toxicity of N-methyl-d-aspartate (NMDA) in the CA1 region of organotypic, mouse hippocampal cultures. Hippocampal cultures from wild-type and cPLA(2)alpha knockout mice were exposed to 5, 7.5 or 10 microm NMDA for 1 h. Toxicity was measured 23 h later. Cultures derived from cPLA(2)alpha(-/-) mice and cultures treated with the selective inhibitor AACOCF(3) were significantly protected from NMDA toxicity, as compared with wild-type cultures. To determine if cPLA(2)alpha-dependent toxicity is cyclooxygenase (COX)-2 dependent, COX-2 and PGE(2) levels were measured 7 and 25 h after NMDA treatment. NMDA treatment failed to induce COX-2 protein or increase PGE(2) in the culture media in either genotype at either time. In contrast, phorbol 12-myristate 13-acetate and ionophore treatment caused robust induction of COX-2 and PGE(2) in both genotypes. We conclude that cPLA(2)alpha may have a hitherto unrecognized direct effect on excitatory neurotoxicity, suggesting that cPLA(2)alpha inhibition is a therapeutic candidate for treatment of the early, excitotoxic injury observed in stroke.
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Affiliation(s)
- Ken M Brady
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
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14
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Hidalgo C, Carrasco MA, Muñoz P, Núñez MT. A role for reactive oxygen/nitrogen species and iron on neuronal synaptic plasticity. Antioxid Redox Signal 2007; 9:245-55. [PMID: 17115937 DOI: 10.1089/ars.2007.9.245] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A great body of experimental evidence collected over many years indicates that calcium has a central role in a variety of neuronal functions. In particular, calcium participates in synaptic plasticity, a neuronal process presumably correlated with cognitive brain functions such as learning and memory. In contrast, only recently, evidence has begun to emerge supporting a physiological role of reactive oxygen (ROS) and nitrogen (RNS) species in synaptic plasticity. This subject will be the central topic of this review. The authors also present recent results showing that, in hippocampal neurons, ROS/RNS, including ROS generated by iron through the Fenton reaction, stimulate ryanodine receptor-mediated calcium release, and how the resulting calcium signals activate the signaling cascades that lead to the transcription of genes known to participate in synaptic plasticity. They discuss the possible participation of ryanodine receptors jointly stimulated by calcium and ROS/RNS in the normal signaling cascades needed for synaptic plasticity, and how too much ROS production may contribute to neurodegeneration via excessive calcium release. In addition, the dual role of iron as a necessary, but potentially toxic, element for normal neuronal function is discussed.
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Affiliation(s)
- Cecilia Hidalgo
- Centro FONDAP de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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15
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Kloda A, Lua L, Hall R, Adams DJ, Martinac B. Liposome reconstitution and modulation of recombinant N-methyl-D-aspartate receptor channels by membrane stretch. Proc Natl Acad Sci U S A 2007; 104:1540-5. [PMID: 17242368 PMCID: PMC1780071 DOI: 10.1073/pnas.0609649104] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Indexed: 11/18/2022] Open
Abstract
In this study, the heteromeric N-methyl-D-aspartate (NMDA) receptor channels composed of NR1a and NR2A subunits were expressed, purified, reconstituted into liposomes, and characterized by using the patch clamp technique. The protein exhibited the expected electrophysiological profile of activation by glutamate and glycine and internal Mg2+ blockade. We demonstrated that the mechanical energy transmitted to membrane-bound NMDA receptor channels can be exerted directly by tension developed in the lipid bilayer. Membrane stretch and application of arachidonic acid potentiated currents through NMDA receptor channels in the presence of intracellular Mg2+. The correlation of membrane tension induced by either mechanical or chemical stimuli with the physiological Mg2+ block of the channel suggests that the synaptic transmission can be altered if NMDA receptor complexes experience local changes in bilayer thickness caused by dynamic targeting to lipid microdomains, electrocompression, or chemical modification of the cell membranes. The ability to study gating properties of NMDA receptor channels in artificial bilayers should prove useful in further study of structure-function relationships and facilitate discoveries of new therapeutic agents for treatment of glutamate-mediated excitotoxicity or analgesic therapies.
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Affiliation(s)
| | - Linda Lua
- SRC Protein Expression Facility, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rhonda Hall
- SRC Protein Expression Facility, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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16
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Latham CF, Osborne SL, Cryle MJ, Meunier FA. Arachidonic acid potentiates exocytosis and allows neuronal SNARE complex to interact with Munc18a. J Neurochem 2006; 100:1543-54. [PMID: 17181552 DOI: 10.1111/j.1471-4159.2006.04286.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neuronal communication relies on the fusion of neurotransmitter-containing vesicles with the neuronal plasma membrane. Recent genetic studies have highlighted the critical role played by polyunsaturated fatty acids in neurotransmission, however, there is little information available about which fatty acids act on exocytosis and, more importantly, by what mechanism. We have used permeabilized chromaffin cells to screen various fatty acids of the n-3 and n-6 series for their acute effects on exocytosis. We have demonstrated that an n-6 series polyunsaturated fatty acid, arachidonic acid, potentiates secretion from intact neurosecretory cells regardless of the secretagogue used. We have shown that arachidonic acid dose dependently increases soluble NSF attachment protein receptor complex formation in chromaffin cells and bovine cortical brain extracts and that a non-hydrolysable analogue of arachidonic acid causes a similar increase in SNARE complex formation. This prompted us to examine the effect of arachidonic acid on SNARE protein interactions with Munc18a, a protein known to prevent Syntaxin1a engagement into the SNARE complex in vitro. In the presence of arachidonic acid, we show that Munc18a can interact with the neuronal SNARE complex in a dose-dependent manner. We further demonstrate that arachidonic acid directly interacts with Syntaxin1a.
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Affiliation(s)
- Catherine F Latham
- Molecular Dynamics of Synaptic Function Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
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17
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Hidalgo C, Carrasco MA, Muñoz P, Núñez MT. A Role for Reactive Oxygen/Nitrogen Species and Iron on Neuronal Synaptic Plasticity. Antioxid Redox Signal 2006. [DOI: 10.1089/ars.2007.9.ft-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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18
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Kowara R, Moraleja KL, Chakravarthy B. Involvement of nitric oxide synthase and ROS-mediated activation of L-type voltage-gated Ca2+ channels in NMDA-induced DPYSL3 degradation. Brain Res 2006; 1119:40-9. [PMID: 16987501 DOI: 10.1016/j.brainres.2006.08.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 08/11/2006] [Accepted: 08/12/2006] [Indexed: 01/27/2023]
Abstract
Dihydropyrimidinase-like 3 (DPYSL3), a member of TUC (TOAD-64/Ulip/CRMP), is believed to play a role in neuronal differentiation, axonal outgrowth and possibly in neuronal regeneration. Recently, we have shown that in primary cortical neurons (PCN) NMDA and oxidative stress (H(2)O(2)) caused a calpain-dependent cleavage of DPYSL3 (62 kDa) resulting in the appearance of a lower molecular weight form (60 kDa) of DPYSL3. Our preliminary results had shown that antioxidants significantly reduced NMDA-induced DPYSL3 degradation, indicating involvement of ROS in calpain activation. The aim of this study was to investigate the possible involvement of NOS in NMDA-induced DPYSL3 degradation. We found that NOS inhibitor (L-NAME) significantly prevented NMDA-induced ROS formation, as well as intracellular Ca(2+) increase [Ca(2+)](i), DPYSL3 degradation and cell death. Further, exposure of PCN to NO donor (SNP) resulted in significant [Ca(2+)](i) increase, ROS generation and probable calpain-mediated DPYSL3 truncation. The NMDA- and oxidative stress (ROS)-induced DPYSL3 truncation was totally dependent on extracellular [Ca(2+)](i). While NMDA-induced DPYSL3 truncation was blocked by both NMDA receptor antagonist (MK801) [Kowara, R., Chen, Q., Milliken, M., Chakravarthy, B., 2005. Calpain-mediated degradation of dihydropyrimidinase-like 3 protein (DPYSL3) in response to NMDA and H(2)O(2) toxicity. J. Neurochem. 95 (2), 466-474] and L-VGCC (nimodipine) inhibitors, H(2)O(2)-induced increase in [Ca(2+)](i), ROS generation and DPYSL3 truncation was blocked only by nimodipine. These results indicate that changes in Ca(2+) homeostasis resulting from ROS-dependent activation of L-VGCC are sufficient to induce probable calpain-mediated DPYSL3 truncation and demonstrate for the first time the role of ROS in the mechanism leading to glutamate-induced calpain activation and DPYSL3 protein degradation. The probable calpain-mediated DPYSL3 truncation may have significant impact on its interaction with actin and its assembly, and in turn on growth cone integrity.
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Affiliation(s)
- Renata Kowara
- National Research Council, Institute for Biological Sciences, M-54, Ottawa, Ontario, Canada K1A 0R6.
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19
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Oz M. Receptor-independent actions of cannabinoids on cell membranes: Focus on endocannabinoids. Pharmacol Ther 2006; 111:114-44. [PMID: 16584786 DOI: 10.1016/j.pharmthera.2005.09.009] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Accepted: 09/30/2005] [Indexed: 01/08/2023]
Abstract
Cannabinoids are a structurally diverse group of mostly lipophilic molecules that bind to cannabinoid receptors. In fact, endogenous cannabinoids (endocannabinoids) are a class of signaling lipids consisting of amides and esters of long-chain polyunsaturated fatty acids. They are synthesized from lipid precursors in plasma membranes via Ca(2+) or G-protein-dependent processes and exhibit cannabinoid-like actions by binding to cannabinoid receptors. However, endocannabinoids can produce effects that are not mediated by these receptors. In pharmacologically relevant concentrations, endocannabinoids modulate the functional properties of voltage-gated ion channels including Ca(2+) channels, Na(+) channels, various types of K(+) channels, and ligand-gated ion channels such as serotonin type 3, nicotinic acetylcholine, and glycine receptors. In addition, modulatory effects of endocannabinoids on other ion-transporting membrane proteins such as transient potential receptor-class channels, gap junctions and transporters for neurotransmitters have also been demonstrated. Furthermore, functional properties of G-protein-coupled receptors for different types of neurotransmitters and neuropeptides are altered by direct actions of endocannabinoids. Although the mechanisms of these effects are currently not clear, it is likely that these direct actions of endocannabinoids are due to their lipophilic structures. These findings indicate that additional molecular targets for endocannabinoids exist and that these targets may represent novel sites for cannabinoids to alter either the excitability of the neurons or the response of the neuronal systems. This review focuses on the results of recent studies indicating that beyond their receptor-mediated effects, endocannabinoids alter the functions of ion channels and other integral membrane proteins directly.
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Affiliation(s)
- Murat Oz
- National Institute on Drug Abuse, NIH/DHHS, Intramural Research Program, Cellular Neurobiology Branch, 5500 Nathan Shock Drive, Baltimore MD, 21224, USA.
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20
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Martel MA, Patenaude C, Ménard C, Alaux S, Cummings BS, Massicotte G. A novel role for calcium-independent phospholipase A in alpha-amino-3-hydroxy-5-methylisoxazole-propionate receptor regulation during long-term potentiation. Eur J Neurosci 2006; 23:505-13. [PMID: 16420457 DOI: 10.1111/j.1460-9568.2005.04565.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
A considerable body of evidence indicates that phospholipase A(2) (PLA(2)) enzymes participate in long-term potentiation (LTP) of excitatory synaptic transmission. In the present study, we have undertaken experiments to identify which calcium-independent isoform of PLA(2) is involved in synaptic plasticity and to determine whether calcium-independent PLA(2) (iPLA(2)) contributes to post-synaptic processes of LTP. Using field recordings from rat CA1 hippocampal slices, we found that theta-burst stimulation (TBS)-induced LTP of field excitatory post-synaptic potentials (fEPSPs) was abolished by the iPLA(2) inhibitor bromoenol lactone (BEL) but not by the Ca(2+)-dependent PLA(2) inhibitor arachidonyl trifluoromethyl ketone (AACOCF(3)). The ionic currents generated during TBS were not affected during iPLA(2) inhibition as BEL by itself had no effect on the magnitude of facilitation during burst responses. In addition, (R)-BEL, an enantioselective inhibitor of iPLA(2)gamma, precluded TBS-induced LTP, an action that was not replicated by the iPLA(2)beta inhibitors (S)-BEL and methyl arachidonyl fluorophosphonate. (R)-BEL was, however, ineffective on pre-established LTP. Finally, BEL also prevented the potentiation of fEPSPs elicited by brief exposure to 50 microM N-methyl-d-aspartate, as well as the associated up-regulation of alpha-amino-3-hydroxy-5-methylisoxazole-propionate (AMPA) receptor GluR1 subunit levels and the increase of (3)H-AMPA binding in crude synaptic fractions. Collectively, these results unravel a new role for iPLA(2)gamma in LTP, which appears to favor the insertion of AMPA receptors at post-synaptic membranes.
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Affiliation(s)
- Marc-André Martel
- Département de chimie-biologie, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, C.P. 500, Trois-Rivières, Québec, Canada G9A 5H7
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21
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Yaksh TL, Kokotos G, Svensson CI, Stephens D, Kokotos CG, Fitzsimmons B, Hadjipavlou-Litina D, Hua XY, Dennis EA. Systemic and Intrathecal Effects of a Novel Series of Phospholipase A2 Inhibitors on Hyperalgesia and Spinal Prostaglandin E2 Release. J Pharmacol Exp Ther 2005; 316:466-75. [PMID: 16203828 DOI: 10.1124/jpet.105.091686] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Phospholipase A(2) (PLA(2)) forms are expressed in spinal cord, and inhibiting spinal PLA(2) induces a potent antihyperalgesia. Here, we examined the antihyperalgesic effects after systemic and i.t. delivery of four compounds constructed with a common motif consisting of a 2-oxoamide with a hydrocarbon tail and a four-carbon tether. These molecules were characterized for their ability to block group IVA calcium-dependent PLA(2) (cPLA(2)) and group VIA calcium-independent PLA(2) (iPLA(2)) in inhibition assays using human recombinant enzyme. The rank ordering of potency in blocking group IVA cPLA(2) was AX048 (ethyl 4-[(2-oxohexadecanoyl)amino]butanoate), AX006 (4-[(2-oxohexadecanoyl)amino]butanoic acid), and AX057 (tert-butyl 4-[(2-oxohexadecanoyl)amino]butanoate) > AX010 (methyl 4-[(2-oxohexadecanoyl)amino]butanoate) and for inhibiting group VIA iPLA(2) was AX048, AX057 > AX006, and AX010. No agent altered recombinant cyclooxygenase activity. In vivo, i.t. (30 mug) and systemic (0.2-3 mg/kg i.p.) AX048 blocked carrageenan hyperalgesia and after systemic delivery in a model of spinally mediated hyperalgesia induced by i.t. substance P (SP). The other agents were without activity. In rats prepared with lumbar i.t. loop dialysis catheters, SP evoked spinal prostaglandin E(2) (PGE(2)) release. AX048 alone inhibited PGE(2) release. Intrathecal SR141617, a cannabinoid CB1 inhibitor at doses that blocked the effects of i.t. anandamide had no effect upon i.t. AX048. These results suggest that AX048 is the first systemically bioavailable compound with a significant affinity for group IVA cPLA(2), which produces a potent antihyperalgesia. The other agents, although demonstrating enzymatic activity in cell-free assays, appear unable to gain access to the intracellular PLA(2) toward which their action is targeted.
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Affiliation(s)
- Tony L Yaksh
- Department of Anesthesiology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0818, USA.
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22
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Rickman C, Davletov B. Arachidonic Acid Allows SNARE Complex Formation in the Presence of Munc18. ACTA ACUST UNITED AC 2005; 12:545-53. [PMID: 15911375 DOI: 10.1016/j.chembiol.2005.03.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 02/21/2005] [Accepted: 03/09/2005] [Indexed: 11/25/2022]
Abstract
SNARE complex formation underlies intracellular membrane fusion in eukaryotic organisms; however, the factors regulating the SNARE assembly are not well understood. The neuronal SNARE complex is composed of synaptobrevin2, SNAP-25, and syntaxin1, the latter being under tight control by the cytosolic protein Munc18. We found that the inhibition of syntaxin1 by Munc18 both in nerve terminals and in defined in vitro reactions can be overcome by specific detergents. This serendipitous finding led us to screen biologically relevant fatty acids, revealing that unsaturated arachidonic and linolenic acids can stimulate Munc18-regulated SNARE complex formation in a direct manner. The direct effect of arachidonic acid on the syntaxin1/Munc18 complex suggests a mechanism for the activation of the SNARE assembly pathway and provides a lead for the further investigation of fatty acids that may regulate SNARE-mediated membrane fusion in eukaryotes.
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Affiliation(s)
- Colin Rickman
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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23
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Bianchi C, Marani L, Barbieri M, Marino S, Beani L, Siniscalchi A. Effects of nociceptin/orphanin FQ and endomorphin-1 on glutamate and GABA release, intracellular [Ca2+] and cell excitability in primary cultures of rat cortical neurons. Neuropharmacology 2004; 47:873-83. [PMID: 15527821 DOI: 10.1016/j.neuropharm.2004.06.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Revised: 05/19/2004] [Accepted: 06/23/2004] [Indexed: 11/30/2022]
Abstract
The effects of nociceptin/orphanin FQ (N/OFQ) and endomorphin-1 (EM-1) on glutamate and GABA release, intracellular calcium, neuronal excitability and glutamate current were investigated in rat primary cortical neuronal cultures. Through their specific receptors N/OFQ and EM-1 (0.02-1 microM) inhibited the electrically evoked outflow of [3H]D-aspartate at most to -50% and that of [3H]GABA to -30%. In addition, at 1 microM, both peptides induced a decrease of the firing rate caused by electrical depolarization. N/OFQ 1-10 microM did not influence either the electrically evoked calcium influx or the glutamate-evoked currents, whereas EM-1 1 microM significantly inhibited them. Thus, in cortical neurons in culture, both N/OFQ and EM-1 inhibited the secretory process and neuronal excitability but EM-1 also affected calcium influx and cell body responsiveness to glutamate. Consequently, EM-1 appeared to dampen this excitatory signal more then N/OFQ did.
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Affiliation(s)
- C Bianchi
- Department of Clinical and Experimental Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, via Fossato di Mortara 17-19, Ferrara 44100, Italy.
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24
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von Bohlen und Halbach O. Nitric oxide imaging in living neuronal tissues using fluorescent probes. Nitric Oxide 2003; 9:217-28. [PMID: 14996429 DOI: 10.1016/j.niox.2004.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 01/13/2004] [Indexed: 11/16/2022]
Abstract
Nitric oxide (NO) is a major modulator of neural functions. Since NO is a gaseous molecule with very short half-life, the spatial distribution of NO and its relationship to neuronal activity are difficult to resolve. Non-invasive and direct visualization of NO in neuronal tissues had been hampered by the lack of a suitable method to identify NO directly. A fluorescent indicator, which directly detects NO under physiological conditions, would be advantageous. Several indicators for direct detection of NO have been developed, which react with NO by forming a fluorescent complex. However, some of these dyes have cytotoxic properties or have been found to be rather unspecific under certain conditions. Fortunately, some of the indicators, which change their fluorescent pattern in the presence of NO, appear to be promising for the visualization of NO. Since little is known about the spatial spread and the temporal aspects of NO release after a specific stimulus, the use of the specific and non-toxic fluorescent NO indicators could provide a potentially powerful tool to study these aspects of NO release in neuronal tissues in vitro and in vivo. Such measurements, especially in combination with electrophysiological recordings, would greatly further NO research. In addition, based on their fluorescent pattern, these NO-sensitive dyes can be distinguished from the calcium-sensitive dye Fura-2, which allows NO-imaging together with calcium-imaging. This article summarizes recent advances and current trends in the visualization of NO in living neuronal tissues.
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Affiliation(s)
- Oliver von Bohlen und Halbach
- Interdisciplinary Center for Neurosciences (IZN), Department of Neuroanatomy, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany.
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