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Wu PY, Lien CC. Modulation of Neurotransmission by Acid-Sensing Ion Channels. JOURNAL OF PHYSIOLOGICAL INVESTIGATION 2024:02275668-990000000-00011. [PMID: 39287486 DOI: 10.4103/ejpi.ejpi-d-24-00062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 07/20/2024] [Indexed: 09/19/2024]
Abstract
ABSTRACT Interstitial pH fluctuations occur normally in the brain and significantly modulate neuronal functions. Acid-sensing ion channels (ASICs), which serve as neuronal acid chemosensors, play important roles in synaptic plasticity, learning, and memory. However, the specific mechanisms by which ASICs influence neurotransmission remain elusive. Here, we report that ASICs modulate transmitter release and axonal excitability at a glutamatergic synapse in the rat and mouse hippocampus. Blocking ASIC1a channels with the tarantula peptide psalmotoxin 1 down-regulates basal transmission and alters short-term plasticity. Notably, the effect of psalmotoxin 1 on ASIC-mediated modulation is age-dependent, occurring only during a limited postnatal period (postnatal weeks 2-6). This finding suggests that protons, through the activation of ASICs, may act as modulators in synapse formation and maturation during early development.
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Affiliation(s)
- Pu-Yeh Wu
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cheng-Chang Lien
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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2
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Evlanenkov KK, Nikolaev MV, Potapieva NN, Bolshakov KV, Tikhonov DB. Probing the Proton-Gated ASIC Channels Using Tetraalkylammonium Ions. Biomolecules 2023; 13:1631. [PMID: 38002313 PMCID: PMC10669046 DOI: 10.3390/biom13111631] [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: 10/20/2023] [Revised: 11/04/2023] [Accepted: 11/05/2023] [Indexed: 11/26/2023] Open
Abstract
The action of tetraalkylammonium ions, from tetrametylammonium (TMA) to tetrapentylammonium (TPtA), on the recombinant and native acid-sensing ion channels (ASICs) was studied using the patch-clamp approach. The responses of ASIC1a, ASIC2a, and native heteromeric ASICs were inhibited by TPtA. The peak currents through ASIC3 were unaffected, whereas the steady-state currents were significantly potentiated. This effect was characterized by an EC50 value of 1.22 ± 0.12 mM and a maximal effect of 3.2 ± 0.5. The effects of TPtA were voltage-independent but significantly decreased under conditions of strong acidification, which caused saturation of ASIC responses. Molecular modeling predicted TPtA binding in the acidic pocket of closed ASICs. Bound TPtA can prevent acidic pocket collapse through a process involving ASIC activation and desensitization. Tetraethylammonium (TEA) inhibited ASIC1a and native ASICs. The effect was independent of the activating pH but decreased with depolarization, suggesting a pore-blocking mechanism.
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Affiliation(s)
| | | | | | | | - Denis B. Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg 194223, Russia or (K.K.E.); (M.V.N.); or (N.N.P.); or (K.V.B.)
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3
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Foster VS, Saez N, King GF, Rank MM. Acute inhibition of acid sensing ion channel 1a after spinal cord injury selectively affects excitatory synaptic transmission, but not intrinsic membrane properties, in deep dorsal horn interneurons. PLoS One 2023; 18:e0289053. [PMID: 37939057 PMCID: PMC10631665 DOI: 10.1371/journal.pone.0289053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/10/2023] [Indexed: 11/10/2023] Open
Abstract
Following a spinal cord injury (SCI), secondary damage mechanisms are triggered that cause inflammation and cell death. A key component of this secondary damage is a reduction in local blood flow that initiates a well-characterised ischemic cascade. Downstream hypoxia and acidosis activate acid sensing ion channel 1a (ASIC1a) to trigger cell death. We recently showed that administration of a potent venom-derived inhibitor of ASIC1a, Hi1a, leads to tissue sparing and improved functional recovery when delivered up to 8 h after ischemic stroke. Here, we use whole-cell patch-clamp electrophysiology in a spinal cord slice preparation to assess the effect of acute ASIC1a inhibition, via a single dose of Hi1a, on intrinsic membrane properties and excitatory synaptic transmission long-term after a spinal cord hemisection injury. We focus on a population of interneurons (INs) in the deep dorsal horn (DDH) that play a key role in relaying sensory information to downstream motoneurons. DDH INs in mice treated with Hi1a 1 h after a spinal cord hemisection showed no change in active or passive intrinsic membrane properties measured 4 weeks after SCI. DDH INs, however, exhibit significant changes in the kinetics of spontaneous excitatory postsynaptic currents after a single dose of Hi1a, when compared to naive animals (unlike SCI mice). Our data suggest that acute ASIC1a inhibition exerts selective effects on excitatory synaptic transmission in DDH INs after SCI via specific ligand-gated receptor channels, and has no effect on other voltage-activated channels long-term after SCI.
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Affiliation(s)
- Victoria S. Foster
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- St George’s, University of London, Medical School, London, England
| | - Natalie Saez
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Michelle M. Rank
- Department of Anatomy and Physiology, School of Biomedical Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia
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Skwarzynska D, Sun H, Kasprzak I, Sharma S, Williamson J, Kapur J. Glycolytic lactate production supports status epilepticus in experimental animals. Ann Clin Transl Neurol 2023; 10:1873-1884. [PMID: 37632130 PMCID: PMC10578888 DOI: 10.1002/acn3.51881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/27/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
OBJECTIVE Status epilepticus (SE) requires rapid intervention to prevent cerebral injury and mortality. The ketogenic diet, which bypasses glycolysis, is a promising remedy for patients with refractory SE. We tested the role of glycolytic lactate production in sustaining SE. METHODS Extracellular lactate and glucose concentration during a seizure and SE in vivo was measured using lactate and glucose biosensors. A lactate dehydrogenase inhibitor, oxamate, blocked pyruvate to lactate conversion during SE. Video-EEG recordings evaluated seizure duration, severity, and immunohistochemistry was used to determine neuronal loss. Genetically encoded calcium indicator GCaMP7 was used to study the effect of oxamate on CA1 pyramidal neurons in vitro. Spontaneous excitatory postsynaptic currents (sEPSCs) were recorded from CA1 neurons to study oxamate's impact on neurotransmission. RESULTS The extracellular glucose concentration dropped rapidly during seizures, and lactate accumulated in the extracellular space. Inhibition of pyruvate to lactate conversion with oxamate terminated SE in mice. There was less neuronal loss in treated compared to control mice. Oxamate perfusion decreased tonic and phasic neuronal activity of GCaMP7-expressing CA1 pyramidal neurons in vitro. Oxamate application reduced the frequency, but not amplitude of sEPSCs recorded from CA1 neurons, suggesting an effect on the presynaptic glutamatergic neurotransmission. INTERPRETATION A single seizure and SE stimulate lactate production. Diminishing pyruvate to lactate conversion with oxamate terminated SE and reduced associated neuronal death. Oxamate reduced neuronal excitability and excitatory neurotransmission at the presynaptic terminal. Glycolytic lactate production sustains SE and is an attractive therapeutic target.
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Affiliation(s)
- Daria Skwarzynska
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Huayu Sun
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Izabela Kasprzak
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Supriya Sharma
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - John Williamson
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Jaideep Kapur
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
- UVA Brain InstituteUniversity of VirginiaCharlottesvilleVirginia22908USA
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5
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Kuzmenkov AI, Peigneur S, Nasburg JA, Mineev KS, Nikolaev MV, Pinheiro-Junior EL, Arseniev AS, Wulff H, Tytgat J, Vassilevski AA. Apamin structure and pharmacology revisited. Front Pharmacol 2022; 13:977440. [PMID: 36188602 PMCID: PMC9523135 DOI: 10.3389/fphar.2022.977440] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/05/2022] [Indexed: 12/02/2022] Open
Abstract
Apamin is often cited as one of the few substances selectively acting on small-conductance Ca2+-activated potassium channels (KCa2). However, published pharmacological and structural data remain controversial. Here, we investigated the molecular pharmacology of apamin by two-electrode voltage-clamp in Xenopus laevis oocytes and patch-clamp in HEK293, COS7, and CHO cells expressing the studied ion channels, as well as in isolated rat brain neurons. The microtitre broth dilution method was used for antimicrobial activity screening. The spatial structure of apamin in aqueous solution was determined by NMR spectroscopy. We tested apamin against 42 ion channels (KCa, KV, NaV, nAChR, ASIC, and others) and confirmed its unique selectivity to KCa2 channels. No antimicrobial activity was detected for apamin against Gram-positive or Gram-negative bacteria. The NMR solution structure of apamin was deposited in the Protein Data Bank. The results presented here demonstrate that apamin is a selective nanomolar or even subnanomolar-affinity KCa2 inhibitor with no significant effects on other molecular targets. The spatial structure as well as ample functional data provided here support the use of apamin as a KCa2-selective pharmacological tool and as a template for drug design.
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Affiliation(s)
- Alexey I. Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | | | - Joshua A. Nasburg
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Konstantin S. Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
| | - Maxim V. Nikolaev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia
| | | | - Alexander S. Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, Belgium
| | - Alexander A. Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
- *Correspondence: Alexander A. Vassilevski,
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6
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Shukralla AA, Dolan E, Delanty N. Acetazolamide: Old drug, new evidence? Epilepsia Open 2022; 7:378-392. [PMID: 35673961 PMCID: PMC9436286 DOI: 10.1002/epi4.12619] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 06/05/2022] [Indexed: 11/24/2022] Open
Abstract
Acetazolamide is an old drug used as an antiepileptic agent, amongst other indications. The drug is seldom used, primarily due to perceived poor efficacy and adverse events. Acetazolamide acts as a noncompetitive inhibitor of carbonic anhydrase, of which there are several subtypes in humans. Acetazolamide causes an acidification of the intracellular and extracellular environments activating acid‐sensing ion channels, and these may account for the anti‐seizure effects of acetazolamide. Other potential mechanisms are modulation of neuroinflammation and attenuation of high‐frequency oscillations. The overall effect increases the seizure threshold in critical structures such as the hippocampus. The evidence for its clinical efficacy was from 12 observational studies of 941 patients. The 50% responder rate was 49%, 20% of patients were rendered seizure‐free, and 30% were noted to have had at least one adverse event. We conclude that the evidence from several observational studies may overestimate efficacy because they lack a comparator; hence, this drug would need further randomized placebo‐controlled trials to assess effectiveness and harm.
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Affiliation(s)
| | - Emma Dolan
- The National Epilepsy Programme, Beaumont Hospital, Dublin, Ireland
| | - Norman Delanty
- The National Epilepsy Programme, Beaumont Hospital, Dublin, Ireland.,FutureNeuro, The SFI Research Centre for Chronic and Rare Neurological Disease, Dublin, Ireland.,Royal College of Surgeons in Ireland, Dublin, Ireland
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7
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Zhu Y, Hu X, Wang L, Zhang J, Pan X, Li Y, Cao R, Li B, Lin H, Wang Y, Zuo L, Huang Y. Recent Advances in Acid-sensitive Ion Channels in Central Nervous System Diseases. Curr Pharm Des 2022; 28:1406-1411. [PMID: 35466865 DOI: 10.2174/1381612828666220422084159] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/24/2022] [Indexed: 11/22/2022]
Abstract
Acid-sensitive ion channels (ASICs) are cationic channels activated by extracellular protons and widely distributed in the nervous system of mammals. It belongs to the ENaC/DEG family and has four coding genes: ASIC1, ASIC2, ASIC3, and ASIC4, which encode eight subunit proteins: ASIC1a, ASIC1b, ASIC1b2, ASIC2a, ASIC2b, ASIC3, ASIC4, and ASIC5. Different subtypes of ASICs have different distributions in the central nervous system, and they play an important role in various physiological and pathological processes of the central nervous system, including synaptic plasticity, anxiety disorders, fear conditioning, depression-related behavior, epilepsy, Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, malignant Glioma, pain, and others. This paper reviewed the recent studies of ASICs on the central nervous system to improve the understanding of ASICs' physiological functions and pathological effects. This article also provides a reference for studying the molecular mechanisms and therapeutic measures of nervous system-related diseases.
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Affiliation(s)
- Yueqin Zhu
- Department of Pharmacy, West Branch of The First Affiliated Hospital of University of Science and Technology of China (Anhui Provincial Cancer Hospital), Hefei, 230031, China
| | - Xiaojie Hu
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Lili Wang
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Jin Zhang
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Xuesheng Pan
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Yangyang Li
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Rui Cao
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Bowen Li
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Huimin Lin
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Yanan Wang
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
| | - Longquan Zuo
- Department of Pharmacy, Hospital of Armed Police of Anhui Province, Hefei 230061, Anhui, China
| | - Yan Huang
- School of Pharmacy, Anhui Medical University, Hefei 230022, Anhui, China
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8
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Choudhary A, Mu C, Barrett KT, Charkhand B, Williams-Dyjur C, Marks WN, Shearer J, Rho JM, Scantlebury MH. The link between brain acidosis, breathing and seizures: a novel mechanism of action for the ketogenic diet in a model of infantile spasms. Brain Commun 2021; 3:fcab189. [PMID: 34734183 DOI: 10.1093/braincomms/fcab189] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2021] [Indexed: 11/12/2022] Open
Abstract
Infantile spasms (IS) syndrome is a catastrophic, epileptic encephalopathy of infancy that is often refractory to current antiepileptic therapies. The ketogenic diet (KD) has emerged as an alternative treatment for patients with medically intractable epilepsy, though the prospective validity and mechanism of action for IS remains largely unexplored. We investigated the KD's efficacy as well as its mechanism of action in a rodent model of intractable IS. The spasms were induced using the triple-hit paradigm and the animals were then artificially reared and put on either the KD (4:1 fats: carbohydrate + protein) or a control milk diet (CM; 1.7:1). 31Phosphorus magnetic resonance spectroscopy (31P MRS) and head-out plethysmography were examined in conjunction with continuous video-EEG behavioural recordings in lesioned animals and sham-operated controls. The KD resulted in a peripheral ketosis observed both in the blood and urine. The KD led to a robust reduction in the frequency of spasms observed, with approximately a 1.5-fold increase in the rate of survival. Intriguingly, the KD resulted in an intracerebral acidosis as measured with 31P MRS. In addition, the respiratory profile of the lesioned rats on the KD was significantly altered with slower, deeper and longer breathing, resulting in decreased levels of expired CO2. Sodium bicarbonate supplementation, acting as a pH buffer, partially reversed the KD's protective effects on spasm frequency. There were no differences in the mitochondrial respiratory profiles in the liver and brain frontal cortex measured between the groups, supporting the notion that the effects of the KD on breathing are not entirely due to changes in intermediary metabolism. Together, our results indicate that the KD produces its anticonvulsant effects through changes in respiration leading to intracerebral acidosis. These findings provide a novel understanding of the mechanisms underlying the anti-seizure effects of the KD in IS. Further research is required to determine whether the effects of the KD on breathing and intracerebral acid-base balance are seen in other paediatric models of epilepsy.
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Affiliation(s)
- Anamika Choudhary
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Chunlong Mu
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Karlene T Barrett
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada
| | - Behshad Charkhand
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christine Williams-Dyjur
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Wendie N Marks
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jane Shearer
- Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jong M Rho
- Departments of Neurosciences and Pediatrics, University of California San Diego (UCSD), San Diego, CA, USA
| | - Morris H Scantlebury
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary Alberta, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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9
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Montalbetti N, Carattino MD. Acid-sensing ion channels modulate bladder nociception. Am J Physiol Renal Physiol 2021; 321:F587-F599. [PMID: 34514879 PMCID: PMC8813206 DOI: 10.1152/ajprenal.00302.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/30/2021] [Accepted: 09/07/2021] [Indexed: 01/23/2023] Open
Abstract
Sensitization of neuronal pathways and persistent afferent drive are major contributors to somatic and visceral pain. However, the underlying mechanisms that govern whether afferent signaling will give rise to sensitization and pain are not fully understood. In the present report, we investigated the contribution of acid-sensing ion channels (ASICs) to bladder nociception in a model of chemical cystitis induced by cyclophosphamide (CYP). We found that the administration of CYP to mice lacking ASIC3, a subunit primarily expressed in sensory neurons, generates pelvic allodynia at a time point at which only modest changes in pelvic sensitivity are apparent in wild-type mice. The differences in mechanical pelvic sensitivity between wild-type and Asic3 knockout mice treated with CYP were ascribed to sensitized bladder C nociceptors. Deletion of Asic3 from bladder sensory neurons abolished their ability to discharge action potentials in response to extracellular acidification. Collectively, the results of our study support the notion that protons and their cognate ASIC receptors are part of a mechanism that operates at the nerve terminals to control nociceptor excitability and sensitization.NEW & NOTEWORTHY Our study indicates that protons and their cognate acid-sensing ion channel receptors are part of a mechanism that operates at bladder afferent terminals to control their function and that the loss of this regulatory mechanism results in hyperactivation of nociceptive pathways and the development of pain in the setting of chemical-induced cystitis.
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Affiliation(s)
- Nicolas Montalbetti
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Marcelo D Carattino
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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10
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Foster VS, Rash LD, King GF, Rank MM. Acid-Sensing Ion Channels: Expression and Function in Resident and Infiltrating Immune Cells in the Central Nervous System. Front Cell Neurosci 2021; 15:738043. [PMID: 34602982 PMCID: PMC8484650 DOI: 10.3389/fncel.2021.738043] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/30/2021] [Indexed: 11/15/2022] Open
Abstract
Peripheral and central immune cells are critical for fighting disease, but they can also play a pivotal role in the onset and/or progression of a variety of neurological conditions that affect the central nervous system (CNS). Tissue acidosis is often present in CNS pathologies such as multiple sclerosis, epileptic seizures, and depression, and local pH is also reduced during periods of ischemia following stroke, traumatic brain injury, and spinal cord injury. These pathological increases in extracellular acidity can activate a class of proton-gated channels known as acid-sensing ion channels (ASICs). ASICs have been primarily studied due to their ubiquitous expression throughout the nervous system, but it is less well recognized that they are also found in various types of immune cells. In this review, we explore what is currently known about the expression of ASICs in both peripheral and CNS-resident immune cells, and how channel activation during pathological tissue acidosis may lead to altered immune cell function that in turn modulates inflammatory pathology in the CNS. We identify gaps in the literature where ASICs and immune cell function has not been characterized, such as neurotrauma. Knowledge of the contribution of ASICs to immune cell function in neuropathology will be critical for determining whether the therapeutic benefits of ASIC inhibition might be due in part to an effect on immune cells.
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Affiliation(s)
- Victoria S. Foster
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Lachlan D. Rash
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, QLD, Australia
| | - Michelle M. Rank
- Anatomy and Physiology, Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
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11
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Gobetto MN, González-Inchauspe C, Uchitel OD. Histamine and Corticosterone Modulate Acid Sensing Ion Channels (ASICs) Dependent Long-term Potentiation at the Mouse Anterior Cingulate Cortex. Neuroscience 2021; 460:145-160. [PMID: 33493620 DOI: 10.1016/j.neuroscience.2021.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/23/2020] [Accepted: 01/12/2021] [Indexed: 11/30/2022]
Abstract
Increase in proton concentration [H+] or decrease in local and global extracellular pH occurs in both physiological and pathological conditions. Acid-sensing ion channels (ASICs), belonging to the ENaC/Deg superfamily, play an important role in signal transduction as proton sensor. ASICs and in particular ASIC1a (one of the six ASICs subunits) which is permeable to Ca2+, are involved in many physiological processes including synaptic plasticity and neurodegenerative diseases. Activity-dependent long-term potentiation (LTP) is a major type of long-lasting synaptic plasticity in the CNS, associated with learning, memory, development, fear and persistent pain. Neurons in the anterior cingulate cortex (ACC) play critical roles in pain perception and chronic pain and express ASIC1a channels. During synaptic transmission, acidification of the synaptic cleft presumably due to the co-release of neurotransmitter and H+ from synaptic vesicles activates postsynaptic ASIC1a channels in ACC of mice. This generates ASIC1a synaptic currents that add to the glutamatergic excitatory postsynaptic currents (EPSCs). Here we report that modulators like histamine and corticosterone, acting through ASIC1a regulate synaptic plasticity, reducing the threshold for LTP induction of glutamatergic EPSCs. Our findings suggest a new role for ASIC1a mediating the neuromodulator action of histamine and corticosterone regulating specific forms of synaptic plasticity in the mouse ACC.
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Affiliation(s)
- María Natalia Gobetto
- Instituto de Fisiología, Biología molecular y Neurociencias (IFIBYNE) CONICET, Departamento de Fisiología, Biología Molecular y Celular "Dr. Héctor Maldonado", Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EGA Ciudad Autónoma de Buenos Aires, Argentina
| | - Carlota González-Inchauspe
- Instituto de Fisiología, Biología molecular y Neurociencias (IFIBYNE) CONICET, Departamento de Fisiología, Biología Molecular y Celular "Dr. Héctor Maldonado", Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EGA Ciudad Autónoma de Buenos Aires, Argentina
| | - Osvaldo D Uchitel
- Instituto de Fisiología, Biología molecular y Neurociencias (IFIBYNE) CONICET, Departamento de Fisiología, Biología Molecular y Celular "Dr. Héctor Maldonado", Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EGA Ciudad Autónoma de Buenos Aires, Argentina.
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12
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Single-cell multimodal transcriptomics to study neuronal diversity in human stem cell-derived brain tissue and organoid models. J Neurosci Methods 2019; 325:108350. [DOI: 10.1016/j.jneumeth.2019.108350] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/24/2019] [Accepted: 07/05/2019] [Indexed: 12/16/2022]
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13
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Cakir Z, Yildirim C, Buran I, Önalan EE, Bal R. Acid-sensing ion channels (ASICs) influence excitability of stellate neurons in the mouse cochlear nucleus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:769-781. [PMID: 31451914 DOI: 10.1007/s00359-019-01365-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 08/08/2019] [Accepted: 08/13/2019] [Indexed: 02/06/2023]
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent and proton-gated channels. In this study, we aimed to test the hypothesis whether ASICs might be involved in modifying the excitability of stellate cells in the cochlear nucleus (CN). We determined gene expressions of ASIC1, ASIC2 and ASIC3 in the CN of BALB/mice. ASIC currents in stellate cells were characterized by using whole-cell patch-clamp technique. In the voltage-clamp experiments, inward currents were recorded upon application of 2-[N-Morpholino ethanesulfonic acid]-normal artificial cerebrospinal fluid (MES-aCSF), whose pH 50 was 5.84. Amiloride inhibited the acid-induced currents in a dose-dependent manner. Inhibition of the ASIC currents by extracellular Ca2+ and Pb2+ (10 μM) was significant evidence for the existence of homomeric ASIC1a subunits. ASIC currents were increased by 20% upon extracellular application of Zn2+ (300 μM) (p < 0.05, n = 13). In current-clamp experiments, application of MES-aCSF resulted in the depolarization of stellate cells. The results show that the ASIC currents in stellate cells of the cochlear nucleus are carried largely by the ASIC1a and ASIC2a channels. ASIC channels affect the excitability of the stellate cells and therefore they appear to have a role in the processing of auditory information.
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Affiliation(s)
- Ziya Cakir
- Department of Physiology, Faculty of Medicine, Tokat Gaziosmanpasa University, 60250, Tokat, Turkey
| | - Caner Yildirim
- Department of Physiology, Faculty of Medicine, Kafkas University, 36100, Kars, Turkey
| | - Ilay Buran
- Department of Medical Biology, Faculty of Medicine, Firat University, 23100, Elazig, Turkey
| | - Ebru Etem Önalan
- Department of Medical Biology, Faculty of Medicine, Firat University, 23100, Elazig, Turkey
| | - Ramazan Bal
- Department of Physiology, Faculty of Medicine, Gaziantep University, 27310, Gaziantep, Turkey.
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14
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Mango D, Nisticò R. Acid-Sensing Ion Channel 1a Is Involved in N-Methyl D-Aspartate Receptor-Dependent Long-Term Depression in the Hippocampus. Front Pharmacol 2019; 10:555. [PMID: 31178731 PMCID: PMC6537656 DOI: 10.3389/fphar.2019.00555] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 05/02/2019] [Indexed: 11/29/2022] Open
Abstract
Acid-sensing ion channels (ASICs), members of the degenerin/epithelial Na+ channel superfamily, are largely expressed in the mammalian nervous system. ASIC1a is highly permeable to Ca2+ and are involved in many physiological processes, including synaptic plasticity, learning, and memory. To clarify the role of ASIC1a in synaptic transmission and plasticity, we investigated N-methyl D-aspartate (NMDA) receptor-dependent long-term depression (LTD) in the CA1 region of the hippocampus. We found that: (1) ASIC1a mediates a component of ASIC1a excitatory postsynaptic currents (EPSCs); (2) ASIC1a plays a role in electrical LTD induced by LFS protocol both in P13-18 and P30-40 animals; (3) ASIC1a is involved in chemical LTD induced by brief bath application of NMDA both in P13-18 and P30-40 animals; and finally (4) a functional interaction between ASIC1a and NMDA receptors occurs during LTD. These findings suggest a new role for ASIC1a in specific forms of synaptic plasticity in the mouse hippocampus.
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Affiliation(s)
- D Mango
- Laboratory of Neuropharmacology, European Brain Research Institute, Rita Levi-Montalcini Foundation, Rome, Italy
| | - R Nisticò
- Laboratory of Neuropharmacology, European Brain Research Institute, Rita Levi-Montalcini Foundation, Rome, Italy.,Department of Biology, School of Pharmacy, University of Rome Tor Vergata, Rome, Italy
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15
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Akanji O, Weinzierl N, Schubert R, Schilling L. Acid sensing ion channels in rat cerebral arteries: Probing the expression pattern and vasomotor activity. Life Sci 2019; 227:193-200. [PMID: 31026454 DOI: 10.1016/j.lfs.2019.04.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 04/17/2019] [Accepted: 04/22/2019] [Indexed: 11/16/2022]
Abstract
AIMS The recent identification of acid sensing ion channels (ASICs) in vascular beds suggests their possible involvement in modulating vasomotor tone. Therefore, we investigated the gene expression profiles of ASIC subtypes in the middle cerebral artery (MCA) of Wistar rats and the functional implication of ASICs in acidosis-induced relaxation as well as maintenance of resting tension. MAIN METHODS Real time PCR was employed to study the pattern of ASIC mRNA expression in the MCA wall in comparison with (i) matching brain tissue samples and (ii) arteries cultured for 24 h and 48 h. The functional implication regarding vasomotor response to acidosis and maintenance of resting tension was assessed using in vitro myography. KEY FINDINGS A robust mRNA expression of ASIC-1, -2 and -4 was found in brain tissue samples and to a lower extent in freshly isolated MCA. In the MCA wall, short term culture induced a down-regulation of ASIC-1 and -2 expression without any remarkable change in ASIC-4 expression. Acidosis induced a pH-related relaxation of freshly isolated MCA ring segments, being more pronounced after short term culture. Incubation with the ASIC blocker amiloride moderately enhanced acidosis-induced relaxation, in cultured MCAs somewhat stronger than in freshly isolated vessels. In addition, amiloride resulted in a decrease of resting tension, albeit only in freshly isolated MCA. SIGNIFICANCE Our results comprehensively describe ASIC subtype composition in the rat MCA in physiological and pathological conditions and strongly suggest the involvement of ASICs in the modulation of vasomotor responses under conditions of normal or decreased pH values.
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Affiliation(s)
- Oluwadamilola Akanji
- Division of Neurosurgical Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Nina Weinzierl
- Division of Neurosurgical Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Rudolf Schubert
- Cardiovascular Physiology, Center for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; European Centre for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Germany
| | - Lothar Schilling
- Division of Neurosurgical Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; European Centre for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Germany.
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16
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Nikolaev MV, Komarova MS, Tikhonova TB, Korosteleva AS, Potapjeva NN, Tikhonov DB. Modulation of Proton-Gated Channels by Antidepressants. ACS Chem Neurosci 2019; 10:1636-1648. [PMID: 30475579 DOI: 10.1021/acschemneuro.8b00560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The chemical structures of some antidepressants are similar to those of recently described amine-containing ligands of acid-sensing ion channels (ASICs). ASICs are expressed in brain neurons and participate in numerous CNS functions. As such, they can be related to antidepressant action or side effects. We therefore studied the actions of a series of antidepressants on recombinant ASIC1a and ASIC2a and on native ASICs in rat brain neurons. Most of the tested compounds prevented steady-state ASIC1a desensitization evoked by conditioning acidification to pH 7.1. Amitriptyline also potentiated ASIC1a responses evoked by pH drops from 7.4 to 6.5. We conclude that amitriptyline has a twofold effect: it shifts activation to less acidic values while also shifting steady-state desensitization to more acidic values. Chlorpromazine, desipramine, amitriptyline, fluoxetine, and atomoxetine potentiated ASIC2a response. Tianeptine caused strong inhibition of ASIC2a. Both potentiation and inhibition of ASIC2a were accompanied by the slowdown of desensitization, suggesting distinct mechanisms of action on activation and desensitization. In experiments on native heteromeric ASICs, tianeptine and amitriptyline demonstrated the same modes of action as on ASIC2a although with reduced potency.
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Affiliation(s)
- Maxim V. Nikolaev
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Margarita S. Komarova
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Tatiana B. Tikhonova
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Anastasia S. Korosteleva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Natalia N. Potapjeva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Denis B. Tikhonov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
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Shteinikov VY, Barygin OI, Gmiro VE, Tikhonov DB. Multiple modes of action of hydrophobic amines and their guanidine analogues on ASIC1a. Eur J Pharmacol 2018; 844:183-194. [PMID: 30557561 DOI: 10.1016/j.ejphar.2018.12.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 01/22/2023]
Abstract
Hydrophobic monoamines containing only a hydrophobic/aromatic moiety and protonated amino group are a recently described class of acid-sensing ion channel (ASIC) modulators. Intensive studies have revealed a number of active compounds including endogenous amines and pharmacological agents and shown that these compounds potentiate and inhibit ASICs depending on their specific structure and on subunit composition of the target channel. The action of monoamines also depends on the application protocol, membrane voltage, conditioning and activating pH, suggesting complex mechanism(s) of the ligand-receptor interaction. Without understanding of these mechanisms analysis of structure-function relationships and predictive search for new potent and selective drugs are hardly possible. To this end, we investigated the modes of action for a representative series of amine and guanidine derivatives of adamantane and phenylcyclohexyl. The study was performed on transfected Chinese hamster ovary (CHO) cells and rat hippocampal interneurons using whole-cell patch clamp recording. We found that complex picture of monoamine action can be rationalized assuming four modes of action: (1) voltage-dependent pore block, (2) acidic shift of activation, (3) alkaline shift of activation and (4) acidic shift of steady-state desensitization. Structure-activity relationships are discussed in the light of this framework. The experiments on native heteromeric ASICs have shown that some of these mechanisms are shared between them and recombinant ASIC1a, implying that our results could also be relevant for amine action in physiological and pathological conditions.
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Affiliation(s)
- Vasilii Y Shteinikov
- I.M.Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg 194223, Russia.
| | - Oleg I Barygin
- I.M.Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg 194223, Russia
| | - Valery E Gmiro
- Institute of Experimental Medicine, RAMS, St. Petersburg 197376, Russia
| | - Denis B Tikhonov
- I.M.Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg 194223, Russia
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18
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Wang Q, Wang Q, Song XL, Jiang Q, Wu YJ, Li Y, Yuan TF, Zhang S, Xu NJ, Zhu MX, Li WG, Xu TL. Fear extinction requires ASIC1a-dependent regulation of hippocampal-prefrontal correlates. SCIENCE ADVANCES 2018; 4:eaau3075. [PMID: 30417090 PMCID: PMC6223961 DOI: 10.1126/sciadv.aau3075] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 09/13/2018] [Indexed: 05/02/2023]
Abstract
Extinction of conditioned fear necessitates the dynamic involvement of hippocampus, medial prefrontal cortex (mPFC), and basolateral amygdala (BLA), but key molecular players that regulate these circuits to achieve fear extinction remain largely unknown. Here, we report that acid-sensing ion channel 1a (ASIC1a) is a crucial molecular regulator of fear extinction, and that this function requires ASIC1a in ventral hippocampus (vHPC), but not dorsal hippocampus, mPFC, or BLA. While genetic disruption or pharmacological inhibition of ASIC1a in vHPC attenuated the extinction of conditioned fear, overexpression of the channel in this area promoted fear extinction. Channelrhodopsin-2-assisted circuit mapping revealed that fear extinction involved an ASIC1a-dependent modification of the long-range hippocampal-prefrontal correlates in a projection-specific manner. Gene expression profiling analysis and validating experiments identified several neuronal activity-regulated and memory-related genes, including Fos, Npas4, and Bdnf, as the potential mediators of ASIC1a regulation of fear extinction. Mechanistically, genetic overexpression of brain-derived neurotrophic factor (BDNF) in vHPC or supplement of BDNF protein in mPFC both rescued the deficiency in fear extinction and the deficits on extinction-driven adaptations of hippocampal-prefrontal correlates caused by the Asic1a gene inactivation in vHPC. Together, these results establish ASIC1a as a critical constituent in fear extinction circuits and thus a promising target for managing adaptive behaviors.
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Affiliation(s)
- Qin Wang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Qi Wang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xing-Lei Song
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Qin Jiang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan-Jiao Wu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying Li
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ti-Fei Yuan
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Siyu Zhang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Nan-Jie Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Michael Xi Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Wei-Guang Li
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Corresponding author. (T.-L.X.); (W.-G.L.)
| | - Tian-Le Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Corresponding author. (T.-L.X.); (W.-G.L.)
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19
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van den Hurk M, Erwin JA, Yeo GW, Gage FH, Bardy C. Patch-Seq Protocol to Analyze the Electrophysiology, Morphology and Transcriptome of Whole Single Neurons Derived From Human Pluripotent Stem Cells. Front Mol Neurosci 2018; 11:261. [PMID: 30147644 PMCID: PMC6096303 DOI: 10.3389/fnmol.2018.00261] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/12/2018] [Indexed: 11/13/2022] Open
Abstract
The human brain is composed of a complex assembly of about 171 billion heterogeneous cellular units (86 billion neurons and 85 billion non-neuronal glia cells). A comprehensive description of brain cells is necessary to understand the nervous system in health and disease. Recently, advances in genomics have permitted the accurate analysis of the full transcriptome of single cells (scRNA-seq). We have built upon such technical progress to combine scRNA-seq with patch-clamping electrophysiological recording and morphological analysis of single human neurons in vitro. This new powerful method, referred to as Patch-seq, enables a thorough, multimodal profiling of neurons and permits us to expose the links between functional properties, morphology, and gene expression. Here, we present a detailed Patch-seq protocol for isolating single neurons from in vitro neuronal cultures. We have validated the Patch-seq whole-transcriptome profiling method with human neurons generated from embryonic and induced pluripotent stem cells (ESCs/iPSCs) derived from healthy subjects, but the procedure may be applied to any kind of cell type in vitro. Patch-seq may be used on neurons in vitro to profile cell types and states in depth to unravel the human molecular basis of neuronal diversity and investigate the cellular mechanisms underlying brain disorders.
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Affiliation(s)
- Mark van den Hurk
- Laboratory for Human Neurophysiology and Genetics, South Australian Health and Medical Research Institute (SAHMRI) Mind and Brain, Adelaide, SA, Australia
| | - Jennifer A. Erwin
- The Lieber Institute for Brain Development, Baltimore, MD, United States
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Gene W. Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, United States
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Fred H. Gage
- Laboratory of Genetics, Salk Institute for Biological Studies, Sanford Consortium for Regenerative Medicine, La Jolla, CA, United States
| | - Cedric Bardy
- Laboratory for Human Neurophysiology and Genetics, South Australian Health and Medical Research Institute (SAHMRI) Mind and Brain, Adelaide, SA, Australia
- Flinders University College of Medicine and Public Health, Adelaide, SA, Australia
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20
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Dual actions of Psalmotoxin at ASIC1a and ASIC2a heteromeric channels (ASIC1a/2a). Sci Rep 2018; 8:7179. [PMID: 29739981 PMCID: PMC5940917 DOI: 10.1038/s41598-018-25386-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/20/2018] [Indexed: 02/06/2023] Open
Abstract
Acid-Sensing Ion Channels (ASICs) are gated by extracellular protons and play important roles in physiological and pathological states, such as pain and stroke. ASIC1a and ASIC2a, two of the most highly expressed subunits in the brain, form functional homo- and hetero-meric (ASIC1a/2a) channels. The function of ASIC1a has been widely studied using psalmotoxin (PcTx1), a venom-derived peptide, as an ASIC1a-selective antagonist. Here, using whole-cell patch clamp, we show that PcTx1 has dual actions at ASIC1a/2a. It can either inhibit or potentiate the heteromeric channel, depending on the conditioning and stimulating pHs. Potent inhibition occurs only at conditioning pHs that begin to desensitize the channel (IC50 = 2.9 nM at pH7.0, a threshold pH for desensitization of ASIC1a/2a). By contrast, potent potentiation can occur at the physiological pH in both CHO cells (EC50 = 56.1 nM) and cortical neurons (threshold concentration < 10 nM). PcTx1 potentiates ASIC1a/2a by increasing the apparent affinity of channel activation for protons. As such, potentiation is the strongest at moderate pHs, diminishing with increasing proton concentrations. Our findings identify PcTx1 as a valuable tool for studying ASIC1a/2a function and contribute significantly to the understanding of the diverse and complex pharmacology of PcTx1.
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21
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Barygin OI, Komarova MS, Tikhonova TB, Korosteleva AS, Nikolaev MV, Magazanik LG, Tikhonov DB. Complex action of tyramine, tryptamine and histamine on native and recombinant ASICs. Channels (Austin) 2017; 11:648-659. [PMID: 29130788 DOI: 10.1080/19336950.2017.1394557] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Proton-gated channels of the ASIC family are widely distributed in the mammalian brain, and, according to the recent data, participate in synaptic transmission. However, ASIC-mediated currents are small, and special efforts are required to detect them. This prompts the search for endogenous ASIC ligands, which can activate or potentiate these channels. A recent finding of the potentiating action of histamine on recombinant homomeric ASIC1a has directed attention to amine-containing compounds. In the present study, we have analyzed the action of histamine, tyramine, and tryptamine on native and recombinant ASICs. None of the compounds caused potentiation of native ASICs in hippocampal interneurons. Furthermore, when applied simultaneously with channel activation, they produced voltage-dependent inhibition. Experiments on recombinant ASIC1a and ASIC2a allowed for an interpretation of these findings. Histamine and tyramine were found to be inactive on the ASIC2a, while tryptamine demonstrated weak inhibition. However, they induce both voltage-dependent inhibition of open channels and voltage-independent potentiation of closed/desensitized channels on the ASIC1a. We suggest that the presence of an ASIC2a subunit in heteromeric native ASICs prevents potentiation but not inhibition. As a result, the inhibitory action of histamine, which is masked by a strong potentiating effect on the ASIC1a homomers, becomes pronounced in experiments with native ASICs.
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Affiliation(s)
- Oleg I Barygin
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Margarita S Komarova
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Tatyana B Tikhonova
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Anastasiia S Korosteleva
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Maxim V Nikolaev
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Lev G Magazanik
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
| | - Denis B Tikhonov
- a I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry , Russian Academy of Sciences , Saint-Petersburg , Russia
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22
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Pelkey KA, Chittajallu R, Craig MT, Tricoire L, Wester JC, McBain CJ. Hippocampal GABAergic Inhibitory Interneurons. Physiol Rev 2017; 97:1619-1747. [PMID: 28954853 DOI: 10.1152/physrev.00007.2017] [Citation(s) in RCA: 495] [Impact Index Per Article: 70.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/16/2017] [Accepted: 05/26/2017] [Indexed: 12/11/2022] Open
Abstract
In the hippocampus GABAergic local circuit inhibitory interneurons represent only ~10-15% of the total neuronal population; however, their remarkable anatomical and physiological diversity allows them to regulate virtually all aspects of cellular and circuit function. Here we provide an overview of the current state of the field of interneuron research, focusing largely on the hippocampus. We discuss recent advances related to the various cell types, including their development and maturation, expression of subtype-specific voltage- and ligand-gated channels, and their roles in network oscillations. We also discuss recent technological advances and approaches that have permitted high-resolution, subtype-specific examination of their roles in numerous neural circuit disorders and the emerging therapeutic strategies to ameliorate such pathophysiological conditions. The ultimate goal of this review is not only to provide a touchstone for the current state of the field, but to help pave the way for future research by highlighting where gaps in our knowledge exist and how a complete appreciation of their roles will aid in future therapeutic strategies.
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Affiliation(s)
- Kenneth A Pelkey
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Ramesh Chittajallu
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Michael T Craig
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Ludovic Tricoire
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Jason C Wester
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Chris J McBain
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
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23
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Engel D. Subcellular Patch-clamp Recordings from the Somatodendritic Domain of Nigral Dopamine Neurons. J Vis Exp 2016. [PMID: 27842379 PMCID: PMC5226116 DOI: 10.3791/54601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding these fundamental functions will shed light on the information transfer in these neurons. Dendritic patch-clamp recordings provide the possibility to directly examine the electrical properties of dendrites and underlying voltage-gated ion channels. However, these fine structures are not easily accessible to patch pipettes because of their small diameter. This report describes a step-by-step procedure to collect stable and reliable recordings from the dendrites of dopaminergic neurons in acute slices. Electrophysiological measurements are combined with post hoc recovery of cell morphology. Successful experiments rely on improved preparation of slices, solutions and pipettes, adequate adjustment of the optics and stability of the pipette in contact with the recorded structure. Standard principles of somatic patch-clamp recording are applied to dendrites but with a gentler approach of the pipette. These versatile techniques can be implemented to address various questions concerning the excitable properties of dendrites.
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24
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Storozhuk M, Kondratskaya E, Nikolaenko L, Krishtal O. A modulatory role of ASICs on GABAergic synapses in rat hippocampal cell cultures. Mol Brain 2016; 9:90. [PMID: 27760555 PMCID: PMC5070181 DOI: 10.1186/s13041-016-0269-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 10/05/2016] [Indexed: 12/27/2022] Open
Abstract
Rapid acidification occurring during synaptic vesicle release can activate acid-sensing ion channels (ASICs) both on pre- and postsynaptic neurons. In the latter case, a fraction of postsynaptic current would be mediated by cation-selective acid-sensing ion channels. Additionally, in both cases, activation of acid-sensing ion channels could modulate synaptic strength by affecting transmitter release and/or sensitivity of postsynaptic receptors. To address potential involvement of acid-sensing ion channels in mediation/modulation of synaptic transmission at hippocampal GABAergic synapses, we studied effects of three structurally different blockers of acid-sensing ion channels on evoked postsynaptic currents using the patch-clamp technique. We found that GABAergic postsynaptic currents, recorded below their reversal potential as inward currents, are suppressed by all the employed blockers of acid-sensing ion channels. These currents were suppressed by ~ 20 % in the presence of a novel blocker 5b (1 μM) and by ~30 % in the presence of either amiloride (25 μM) or diminazene (20 μM). In the same cells the suppression of postsynaptic currents, recorded above their reversal potential as outward currents was statistically insignificant. These results imply that the effects of blockers in our experiments are at least partially postsynaptic. On the other hand, in the case of mediation of a fraction of postsynaptic current by acid-sensing ion channels, an increase of outward currents would be expected under our experimental conditions. Our analysis of a bicuculline-resistant fraction of postsynaptic currents also suggests that effects of the blockers are predominantly modulatory. In this work we present evidence for the first time that acid-sensing ion channels play a functional role at hippocampal GABAergic synapses. The suppressing effect of the blockers of acid-sensing ion channels on GABAergic transmission is due, at least partially, to a postsynaptic but (predominantly) modulatory mechanism. We hypothesize that the modulatory effect is due to functional crosstalk between ASICs and GABAA-receptors recently reported in isolated neurons, however, verification of this hypothesis is necessary.
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Affiliation(s)
- Maksim Storozhuk
- Bogomoletz Institute of Physiology, Bogomoletz st. 4, Kiev, Ukraine. .,State Key Laboratory of Molecular and Cellular Biology, Bogomoletz st. 4, Kiev, Ukraine.
| | - Elena Kondratskaya
- Bogomoletz Institute of Physiology, Bogomoletz st. 4, Kiev, Ukraine.,State Key Laboratory of Molecular and Cellular Biology, Bogomoletz st. 4, Kiev, Ukraine
| | | | - Oleg Krishtal
- Bogomoletz Institute of Physiology, Bogomoletz st. 4, Kiev, Ukraine.,State Key Laboratory of Molecular and Cellular Biology, Bogomoletz st. 4, Kiev, Ukraine
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25
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Yang F, Sun X, Ding Y, Ma H, Yang TO, Ma Y, Wei D, Li W, Xu T, Jiang W. Astrocytic Acid-Sensing Ion Channel 1a Contributes to the Development of Chronic Epileptogenesis. Sci Rep 2016; 6:31581. [PMID: 27526777 PMCID: PMC4985693 DOI: 10.1038/srep31581] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 07/26/2016] [Indexed: 12/14/2022] Open
Abstract
Unraveling mechanisms underlying epileptogenesis after brain injury is an unmet medical challenge. Although histopathological studies have revealed that reactive astrogliosis and tissue acidosis are prominent features in epileptogenic foci, their roles in epileptogenesis remain unclear. Here, we explored whether astrocytic acid-sensing ion channel-1a (ASIC1a) contributes to the development of chronic epilepsy. High levels of ASIC1a were measured in reactive astrocytes in the hippocampi of patients with temporal lobe epilepsy (TLE) and epileptic mice. Extracellular acidosis caused a significant Ca2+ influx in cultured astrocytes, and this influx was sensitive to inhibition by the ASIC1a-specific blocker psalmotoxin 1 (PcTX1). In addition, recombinant adeno-associated virus (rAAV) vectors carrying a GFAP promoter in conjunction with ASIC1a shRNA or cDNA were generated to suppress or restore, respectively, ASIC1a expression in astrocytes. Injection of rAAV-ASIC1a-shRNA into the dentate gyrus of the wide type TLE mouse model resulted in the inhibition of astrocytic ASIC1a expression and a reduction in spontaneous seizures. By contrast, rAAV-ASIC1a-cDNA restored astrocytic ASIC1a expression in an ASIC1a knock-out TLE mouse model and increased the frequency of spontaneous seizures. Taken together, our results reveal that astrocytic ASIC1a may be an attractive new target for the treatment of epilepsy.
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Affiliation(s)
- Feng Yang
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Xiaolong Sun
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Yinxiu Ding
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China.,The Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan 750004, China
| | - Hui Ma
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Tangpeng Ou Yang
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Yue Ma
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Dong Wei
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Wen Li
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
| | - Tianle Xu
- Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Wen Jiang
- Department of Neurology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
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26
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Revisiting the Lamotrigine-Mediated Effect on Hippocampal GABAergic Transmission. Int J Mol Sci 2016; 17:ijms17071191. [PMID: 27455251 PMCID: PMC4964560 DOI: 10.3390/ijms17071191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 07/19/2016] [Indexed: 01/07/2023] Open
Abstract
Lamotrigine (LTG) is generally considered as a voltage-gated sodium (Nav) channel blocker. However, recent studies suggest that LTG can also serve as a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel enhancer and can increase the excitability of GABAergic interneurons (INs). Perisomatic inhibitory INs, predominantly fast-spiking basket cells (BCs), powerfully inhibit granule cells (GCs) in the hippocampal dentate gyrus. Notably, BCs express abundant Nav channels and HCN channels, both of which are able to support sustained action potential generation. Using whole-cell recording in rat hippocampal slices, we investigated the net LTG effect on BC output. We showed that bath application of LTG significantly decreased the amplitude of evoked compound inhibitory postsynaptic currents (IPSCs) in GCs. In contrast, simultaneous paired recordings from BCs to GCs showed that LTG had no effect on both the amplitude and the paired-pulse ratio of the unitary IPSCs, suggesting that LTG did not affect GABA release, though it suppressed cell excitability. In line with this, LTG decreased spontaneous IPSC (sIPSC) frequency, but not miniature IPSC frequency. When re-examining the LTG effect on GABAergic transmission in the cornus ammonis region 1 (CA1) area, we found that LTG markedly inhibits both the excitability of dendrite-targeting INs in the stratum oriens and the concurrent sIPSCs recorded on their targeting pyramidal cells (PCs) without significant hyperpolarization-activated current (Ih) enhancement. In summary, LTG has no effect on augmenting Ih in GABAergic INs and does not promote GABAergic inhibitory output. The antiepileptic effect of LTG is likely through Nav channel inhibition and the suppression of global neuronal network activity.
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27
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Krauson AJ, Carattino MD. The Thumb Domain Mediates Acid-sensing Ion Channel Desensitization. J Biol Chem 2016; 291:11407-19. [PMID: 27015804 DOI: 10.1074/jbc.m115.702316] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Indexed: 11/06/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are cation-selective proton-gated channels expressed in neurons that participate in diverse physiological processes, including nociception, synaptic plasticity, learning, and memory. ASIC subunits contain intracellular N and C termini, two transmembrane domains that constitute the pore, and a large extracellular loop with defined domains termed the finger, β-ball, thumb, palm, and knuckle. Here we examined the contribution of the finger, β-ball, and thumb domains to activation and desensitization through the analysis of chimeras and the assessment of the effect of covalent modification of introduced Cys at the domain-domain interfaces. Our studies with ASIC1a-ASIC2a chimeras showed that swapping the thumb domain between subunits results in faster channel desensitization. Likewise, the covalent modification of Cys residues at selected positions in the β-ball-thumb interface accelerates the desensitization of the mutant channels. Studies of accessibility with thiol-reactive reagents revealed that the β-ball and thumb domains reside apart in the resting state but that they become closer to each other in response to extracellular acidification. We propose that the thumb domain moves upon continuous exposure to an acidic extracellular milieu, assisting with the closing of the pore during channel desensitization.
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Affiliation(s)
- Aram J Krauson
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - Marcelo D Carattino
- From the Renal-Electrolyte Division, Department of Medicine, and Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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28
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Liu MG, Li HS, Li WG, Wu YJ, Deng SN, Huang C, Maximyuk O, Sukach V, Krishtal O, Zhu MX, Xu TL. Acid-sensing ion channel 1a contributes to hippocampal LTP inducibility through multiple mechanisms. Sci Rep 2016; 6:23350. [PMID: 26996240 PMCID: PMC4800407 DOI: 10.1038/srep23350] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/02/2016] [Indexed: 12/30/2022] Open
Abstract
The exact roles of acid-sensing ion channels (ASICs) in synaptic plasticity remain elusive. Here, we address the contribution of ASIC1a to five forms of synaptic plasticity in the mouse hippocampus using an in vitro multi-electrode array recording system. We found that genetic deletion or pharmacological blockade of ASIC1a greatly reduced, but did not fully abolish, the probability of long-term potentiation (LTP) induction by either single or repeated high frequency stimulation or theta burst stimulation in the CA1 region. However, these treatments did not affect hippocampal long-term depression induced by low frequency electrical stimulation or (RS)-3,5-dihydroxyphenylglycine. We also show that ASIC1a exerts its action in hippocampal LTP through multiple mechanisms that include but are not limited to augmentation of NMDA receptor function. Taken together, these results reveal new insights into the role of ASIC1a in hippocampal synaptic plasticity and the underlying mechanisms. This unbiased study also demonstrates a novel and objective way to assay synaptic plasticity mechanisms in the brain.
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Affiliation(s)
- Ming-Gang Liu
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hu-Song Li
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei-Guang Li
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Department of Developmental and Behavioral Pediatrics, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Yan-Jiao Wu
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shi-Ning Deng
- Department of Developmental and Behavioral Pediatrics, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Chen Huang
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Oleksandr Maximyuk
- Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Volodymyr Sukach
- Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Oleg Krishtal
- Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin St., Houston, TX 77030, USA
| | - Tian-Le Xu
- Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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29
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Wu J, Xu Y, Jiang YQ, Xu J, Hu Y, Zha XM. ASIC subunit ratio and differential surface trafficking in the brain. Mol Brain 2016; 9:4. [PMID: 26746198 PMCID: PMC4706662 DOI: 10.1186/s13041-016-0185-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 01/04/2016] [Indexed: 12/31/2022] Open
Abstract
Background Acid-sensing ion channels (ASICs) are key mediators of acidosis-induced responses in neurons. However, little is known about the relative abundance of different ASIC subunits in the brain. Such data are fundamental for interpreting the relative contribution of ASIC1a homomers and 1a/2 heteromers to acid signaling, and essential for designing therapeutic interventions to target these channels. We used a simple biochemical approach and semi-quantitatively determined the molar ratio of ASIC1a and 2 subunits in mouse brain. Further, we investigated differential surface trafficking of ASIC1a, ASIC2a, and ASIC2b. Results and conclusions ASIC1a subunits outnumber the sum of ASIC2a and ASIC2b. There is a region-specific variation in ASIC2a and 2b expression, with cerebellum and striatum expressing predominantly 2b and 2a, respectively. Further, we performed surface biotinylation and found that surface ASIC1a and ASIC2a ratio correlates with their total expression. In contrast, ASIC2b exhibits little surface presence in the brain. This result is consistent with increased co-localization of ASIC2b with an ER marker in 3T3 cells. Our data are the first semi-quantitative determination of relative subunit ratio of various ASICs in the brain. The differential surface trafficking of ASICs suggests that the main functional ASICs in the brain are ASIC1a homomers and 1a/2a heteromers. This finding provides important insights into the relative contribution of various ASIC complexes to acid signaling in neurons.
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Affiliation(s)
- Junjun Wu
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Yuanyuan Xu
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
| | - Yu-Qing Jiang
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,Department of Urology, The Third Hospital of Hebei Medical University, Shijiazhuang, HeBei, China.
| | - Jiangping Xu
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
| | - Youjia Hu
- China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Xiang-ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA.
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30
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Acid-sensing ion channel (ASIC) 4 predominantly localizes to an early endosome-related organelle upon heterologous expression. Sci Rep 2015; 5:18242. [PMID: 26667795 PMCID: PMC4678866 DOI: 10.1038/srep18242] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 10/23/2015] [Indexed: 12/25/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent proton-gated amiloride sensitive sodium channels, belonging to the DEG/ENaC gene family. Six different ASICs have been identified (ASIC1a, ASIC1b, ASIC2a, ASIC2b, ASIC3, ASIC4) that are activated by a drop in extracellular pH, either as homo- or heteromers. An exception is ASIC4, which is not activated by protons as a homomer and which does not contribute to functional heteromeric ASICs. Insensitivity of ASIC4 to protons and its comparatively low sequence identity to other ASICs (45%) raises the question whether ASIC4 may have different functions than other ASICs. In this study, we therefore investigated the subcellular localization of ASIC4 in heterologous cell lines, which revealed a surprising accumulation of the channel in early endosome-related vacuoles. Moreover, we identified an unique amino-terminal motif as important for forward-trafficking from the ER/Golgi to the early endosome-related compartment. Collectively, our results show that heterologously expressed ASIC4 predominantly resides in an intracellular endosomal compartment.
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31
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Zhou RP, Wu XS, Wang ZS, Xie YY, Ge JF, Chen FH. Novel Insights into Acid-Sensing Ion Channels: Implications for Degenerative Diseases. Aging Dis 2015; 7:491-501. [PMID: 27493834 DOI: 10.14336/ad.2015.1213] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 12/13/2015] [Indexed: 12/16/2022] Open
Abstract
Degenerative diseases often strike older adults and are characterized by progressive deterioration of cells, eventually leading to tissue and organ degeneration for which limited effective treatment options are currently available. Acid-sensing ion channels (ASICs), a family of extracellular H(+)-activated ligand-gated ion channels, play critical roles in physiological and pathological conditions. Aberrant activation of ASICs is reported to regulate cell apoptosis, differentiation and autophagy. Accumulating evidence has highlighted a dramatic increase and activation of ASICs in degenerative disorders, including multiple sclerosis, Parkinson's disease, Huntington's disease, intervertebral disc degeneration and arthritis. In this review, we have comprehensively discussed the critical roles of ASICs and their potential utility as therapeutic targets in degenerative diseases.
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Affiliation(s)
- Ren-Peng Zhou
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Xiao-Shan Wu
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Zhi-Sen Wang
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Ya-Ya Xie
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Jin-Fang Ge
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Fei-Hu Chen
- 1Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; 2The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
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32
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Osmakov DI, Andreev YA, Kozlov SA. Acid-sensing ion channels and their modulators. BIOCHEMISTRY (MOSCOW) 2015; 79:1528-45. [PMID: 25749163 DOI: 10.1134/s0006297914130069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
According to a modern look acid-sensing ion channels (ASICs) are one of the most important receptors that perceive pH change in the body. ASICs represent proton-gated Na+-selective channels, which are expressed in neurons of the central and peripheral nervous system. These channels are attracting attention of researchers around the world, as they are involved in various physiological processes in the body. Drop of pH may occur in tissues in norm (e.g. the accumulation of lactic acid, the release of protons upon ATP hydrolysis) and pathology (inflammation, ischemic stroke, tissue damage and seizure). These processes are accompanied by unpleasant pain sensations, which may be short-lived or can lead to chronic inflammatory diseases. Modulators of ASIC channels activity are potential candidates for new effective analgesic and neuroprotection drugs. This review summarizes available information about structure, function, and physiological role of ASIC channels. In addition a description of all known ligands of these channels and their practical relevance is provided.
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Affiliation(s)
- D I Osmakov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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33
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Hsu TT, Lee CT, Tai MH, Lien CC. Differential Recruitment of Dentate Gyrus Interneuron Types by Commissural Versus Perforant Pathways. Cereb Cortex 2015; 26:2715-27. [DOI: 10.1093/cercor/bhv127] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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34
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Chiang PH, Chien TC, Chen CC, Yanagawa Y, Lien CC. ASIC-dependent LTP at multiple glutamatergic synapses in amygdala network is required for fear memory. Sci Rep 2015; 5:10143. [PMID: 25988357 PMCID: PMC4437300 DOI: 10.1038/srep10143] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/31/2015] [Indexed: 11/17/2022] Open
Abstract
Genetic variants in the human ortholog of acid-sensing ion channel-1a subunit (ASIC1a) gene are associated with panic disorder and amygdala dysfunction. Both fear learning and activity-induced long-term potentiation (LTP) of cortico-basolateral amygdala (BLA) synapses are impaired in ASIC1a-null mice, suggesting a critical role of ASICs in fear memory formation. In this study, we found that ASICs were differentially expressed within the amygdala neuronal population, and the extent of LTP at various glutamatergic synapses correlated with the level of ASIC expression in postsynaptic neurons. Importantly, selective deletion of ASIC1a in GABAergic cells, including amygdala output neurons, eliminated LTP in these cells and reduced fear learning to the same extent as that found when ASIC1a was selectively abolished in BLA glutamatergic neurons. Thus, fear learning requires ASIC-dependent LTP at multiple amygdala synapses, including both cortico-BLA input synapses and intra-amygdala synapses on output neurons.
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Affiliation(s)
- Po-Han Chiang
- Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
| | - Ta-Chun Chien
- Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine and JST, CREST, Maebashi 371-8511, Japan
| | - Cheng-Chang Lien
- 1] Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan [2] Institute of Brain Science, National Yang-Ming University, Taipei 112, Taiwan [3] Brain Research Center, National Yang-Ming University, Taipei 112, Taiwan
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35
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Lin SH, Chien YC, Chiang WW, Liu YZ, Lien CC, Chen CC. Genetic mapping of ASIC4 and contrasting phenotype to ASIC1a in modulating innate fear and anxiety. Eur J Neurosci 2015; 41:1553-68. [PMID: 25828470 DOI: 10.1111/ejn.12905] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 01/23/2023]
Abstract
Although ASIC4 is a member of the acid-sensing ion channel (ASIC) family, we have limited knowledge of its expression and physiological function in vivo. To trace the expression of this ion channel, we generated the ASIC4-knockout/CreERT(2)-knockin (Asic4(Cre) (ERT) (2)) mouse line. After tamoxifen induction in the Asic4(Cre) (ERT)(2)::CAG-STOP(floxed)-Td-tomato double transgenic mice, we mapped the expression of ASIC4 at the cellular level in the central nervous system (CNS). ASIC4 was expressed in many brain regions, including the olfactory bulb, cerebral cortex, striatum, hippocampus, amygdala, thalamus, hypothalamus, brain stem, cerebellum, spinal cord and pituitary gland. Colocalisation studies further revealed that ASIC4 was expressed mainly in three types of cells in the CNS: (i) calretinin (CR)-positive and/or vasoactive intestine peptide (VIP)-positive interneurons; (ii) neural/glial antigen 2 (NG2)-positive glia, also known as oligodendrocyte precursor cells; and (iii) cerebellar granule cells. To probe the possible role of ASIC4, we hypothesised that ASIC4 could modulate the membrane expression of ASIC1a and thus ASIC1a signaling in vivo. We conducted behavioral phenotyping of Asic4(Cre) (ERT)(2) mice by screening many of the known behavioral phenotypes found in Asic1a knockouts and found ASIC4 not involved in shock-evoked fear learning and memory, seizure termination or psychostimulant-induced locomotion/rewarding effects. In contrast, ASIC4 might play an important role in modulating the innate fear response to predator odor and anxious state because ASIC4-mutant mice showed increased freezing response to 2,4,5-trimethylthiazoline and elevated anxiety-like behavior in both the open-field and elevated-plus maze. ASIC4 may modulate fear and anxiety by counteracting ASIC1a activity in the brain.
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Affiliation(s)
- Shing-Hong Lin
- Graduate institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, 115, Taiwan
| | - Ya-Chih Chien
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 115, Taiwan
| | - Wei-Wei Chiang
- Taiwan Mouse Clinic-National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei, Taiwan
| | - Yan-Zhen Liu
- Taiwan Mouse Clinic-National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei, Taiwan
| | - Cheng-Chang Lien
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Cheng Chen
- Graduate institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, 115, Taiwan.,Taiwan Mouse Clinic-National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei, Taiwan
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36
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Cao Q, Wang W, Gu J, Jiang G, Wang K, Xu Z, Li J, Chen G, Wang X. Elevated Expression of Acid-Sensing Ion Channel 3 Inhibits Epilepsy via Activation of Interneurons. Mol Neurobiol 2014; 53:485-498. [PMID: 25476599 DOI: 10.1007/s12035-014-9014-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 11/18/2014] [Indexed: 12/21/2022]
Abstract
Recent studies have indicated that acid-sensing ion channels may play a significant role in the termination of epilepsy. In particular, acid-sensing ion channel 3 (ASIC3) is expressed in the central nervous system and is most sensitive to extracellular pH. However, whether ASIC3 plays a role in epilepsy is unknown. In this study, qRT-PCR, Western blot, immunohistochemistry, double immunofluorescence labeling, and slice recordings were used. We first detected elevated ASIC3 expression patterns in the brains of temporal lobe epilepsy patients and epileptic rats. ASIC3 was expressed in neurons and glia in both humans and in an experimental model of epilepsy, and ASIC3 was colocalized with inhibitory GABAergic interneurons. By blocking ASIC3 with its antagonist APETx2, we observed that injected APETx2 shortened the latency to seizure and increased the incidence of generalized tonic clonic seizure compared to the control group in models of both pilocarpine- and pentylenetetrazole (PTZ)-induced seizures. Additionally, blocking ASIC3 significantly decreased the frequency of action potential (AP) firing in interneurons. Moreover, APETx2 significantly reduced the amplitudes and frequencies of miniature inhibitory postsynaptic currents (mIPSCs) while showed no differences with the APETx2 + bicuculline group and the bicuculline group. These findings suggest that elevated levels of ASIC3 may serve as an anti-epileptic mechanism via postsynaptic mechanisms in interneurons. It could represent a novel therapeutic strategy for epilepsy treatment.
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Affiliation(s)
- Qingqing Cao
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China.,Department of Neurology, The People's Hospital of Bishan District, 82 Xinsheng Road, Chongqing, 402760, China
| | - Wei Wang
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China
| | - Juan Gu
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China
| | - Guohui Jiang
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College, 63 Wenhua Road, Nanchong, 637000, China
| | - Kewei Wang
- Department of Pharmacology, Peking University, 5 Summer Palace road, Beijing, 100871, China
| | - Zucai Xu
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China
| | - Jie Li
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China
| | - Guojun Chen
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China.
| | - Xuefeng Wang
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, 1Youyi Rd, Chongqing, 400016, China. .,Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China.
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Mladin C, Ciobica A, Lefter R, Popescu A, Bild W. Deuterium-depleted water has stimulating effects on long-term memory in rats. Neurosci Lett 2014; 583:154-8. [PMID: 25263786 DOI: 10.1016/j.neulet.2014.09.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 09/18/2014] [Indexed: 01/13/2023]
Abstract
Deuterium-depleted water (DDW) is a water which has a 6-7-fold less concentration of the naturally occurring deuterium (20-25ppm vs. 150ppm). While administrated for a longer period, it may reduce the concentration of deuterium throughout the body, thus activating cellular mechanisms which are depending on protons (channels, pumps, enzyme proteins). The aim of the present work was to study, for the first time in our knowledge, the possible influence of deuterium-depleted water (DDW) chronic administration in normal Wistar rats, as compared to a control group which received distilled water, on spatial working memory and the locomotor activity (as studied through Y-maze) or both short-term and long-term spatial memory (assed in radial 8 arms-maze task). Our results presented here showed no significant modifications in terms of spatial working memory (assessed through spontaneous alternation percentage) and locomotor activity (expressed through the number of arm entries) in Y-maze, as a result of DDW ingestion. Also, no significant differences between the DDW and control group were found in terms of the number of working memory errors in the eight-arm radial maze, as a parameter of short-term memory. Still, we observed a significant decrease for the number of reference memory errors in the DDW rats. In this way, we could speculate that the administration of DDW may generate an improvement of the reference memory, as an index of long-term memory. Thus, we can reach the conclusion that the change between the deuterium/hydrogen balance may have important consequences for the mechanisms that govern long-term memory, as showed here especially in the behavioral parameters from the eight-arm radial maze task.
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Affiliation(s)
- Cristian Mladin
- University of Craiova, Faculty of Chemistry, Craiova, Romania
| | - Alin Ciobica
- Alexandru Ioan Cuza University, 11 Carol I Blvd., 700506 Iasi, Romania; Center of Biomedical Research of the Romanian Academy, Iasi Branch, Romania.
| | - Radu Lefter
- Romanian Academy Iasi Branch, SOP HRD/159/1.5/S/133675 Project
| | | | - Walther Bild
- Center of Biomedical Research of the Romanian Academy, Iasi Branch, Romania; Gr. T. Popa University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
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Tikhonova TB, Nagaeva EI, Barygin OI, Potapieva NN, Bolshakov KV, Tikhonov DB. Monoamine NMDA receptor channel blockers inhibit and potentiate native and recombinant proton-gated ion channels. Neuropharmacology 2014; 89:1-10. [PMID: 25196733 DOI: 10.1016/j.neuropharm.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 07/15/2014] [Accepted: 08/26/2014] [Indexed: 10/24/2022]
Abstract
Acid-sensing ion channels (ASICs) are widely distributed in the peripheral and central nervous system. Although they are involved in many physiological functions, the actual processes that activate ASICs remain unclear. This is particularly true for brain ASICs, which produce only a transient response to a fast drop in pH and cannot mediate sustained current. Therefore, the search for ASIC inhibitors and, especially, potentiators/activators is important. We report that NMDA receptor channel blockers with a comparatively simple structure (9-aminoacridine, memantine, IEM-2117 and IEM-1921) potentiate and/or inhibit ASICs in submillimolar concentrations. The experiments were performed using the patch clamp technique on native ASICs from rat hippocampal interneurons and recombinant ASICs of different subunit compositions expressed in CHO cells. Native ASICs were potentiated by IEM-1921 and IEM-2117, and inhibited by memantine and 9-aminoacridine. Homomeric ASIC1a were inhibited by memantine, IEM-2117 and 9-aminoacridine while IEM-1921 was ineffective. In contrast, homomeric ASIC2a were potentiated by IEM-2117, memantine and IEM-1921, whereas 9-aminoacridine was inactive. The compounds caused a complex effect on ASIC3. 9-aminoacridine and IEM-1921 potentiated the steady-state response of ASIC3 and inhibited the peak component. IEM-2117 not only potentiated ASIC3-mediated currents caused by acidification but also evoked steady-state currents at neutral pH. Our results demonstrate that, depending on the subunit composition, ASICs can be activated or inhibited by simple compounds that possess only amino group and aromatic/hydrophobic moieties. This opens up the possibility to search for new ASIC modulators among a number of endogenous ligands.
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Affiliation(s)
- Tatiana B Tikhonova
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia
| | - Elina I Nagaeva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia
| | - Oleg I Barygin
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia
| | - Natalia N Potapieva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia
| | - Konstantin V Bolshakov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia
| | - Denis B Tikhonov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, 44 Thorez pr., St.Petersburg, Russia.
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Zhao D, Ning N, Lei Z, Sun H, Wei C, Chen D, Li J. Identification of a novel protein complex containing ASIC1a and GABAA receptors and their interregulation. PLoS One 2014; 9:e99735. [PMID: 24923912 PMCID: PMC4055689 DOI: 10.1371/journal.pone.0099735] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 05/15/2014] [Indexed: 11/18/2022] Open
Abstract
Acid-sensing ion channels (ASICs) belong to the family of the epithelial sodium channel/degenerin (ENaC/DEG) and are activated by extracellular protons. They are widely distributed within both the central and peripheral nervous systems. ASICs were modified by the activation of γ-aminobutyric acid receptors (GABAA), a ligand-gated chloride channels, in hippocampal neurons. In contrast, the activity of GABAA receptors were also modulated by extracellular pH. However so far, the mechanisms underlying this intermodulation remain obscure. We hypothesized that these two receptors-GABAA receptors and ASICs channels might form a novel protein complex and functionally interact with each other. In the study reported here, we found that ASICs were modified by the activation of GABAA receptors either in HEK293 cells following transient co-transfection of GABAA and ASIC1a or in primary cultured dorsal root ganglia (DRG) neurons. Conversely, activation of ASIC1a also modifies the GABAA receptor-channel kinetics. Immunoassays showed that both GABAA and ASIC1a proteins were co-immunoprecipitated mutually either in HEK293 cells co-transfected with GABAA and ASIC1a or in primary cultured DRG neurons. Our results indicate that putative GABAA and ASIC1a channels functionally interact with each other, possibly via an inter-molecular association by forming a novel protein complex.
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Affiliation(s)
- Dongbo Zhao
- Department of Thoracic Surgery, Shandong Cancer Hospital and Institute, Jinan, China
| | - Nannan Ning
- Department of Physiology, School of Medicine, Shandong University, Jinan, China
| | - Zhen Lei
- Department of Anesthesiology, Qilu Hospital, Shandong University, Jinan, China
| | - Hua Sun
- Department of Thoracic Surgery, Shandong Cancer Hospital and Institute, Jinan, China
| | - Chuanfei Wei
- Department of Physiology, School of Medicine, Shandong University, Jinan, China
| | - Dawei Chen
- Department of Physiology, School of Medicine, Shandong University, Jinan, China
| | - Jingxin Li
- Department of Physiology, School of Medicine, Shandong University, Jinan, China
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Li MH, Liu SQ, Inoue K, Lan J, Simon RP, Xiong ZG. Acid-sensing ion channels in mouse olfactory bulb M/T neurons. ACTA ACUST UNITED AC 2014; 143:719-31. [PMID: 24821964 PMCID: PMC4035746 DOI: 10.1085/jgp.201310990] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Functional acid-sensing ion channels are present in olfactory bulb neurons and may contribute to normal olfaction. The olfactory bulb contains the first synaptic relay in the olfactory pathway, the sensory system in which odorants are detected enabling these chemical stimuli to be transformed into electrical signals and, ultimately, the perception of odor. Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are widely expressed in neurons of the central nervous system. However, no direct electrophysiological and pharmacological characterizations of ASICs in olfactory bulb neurons have been described. Using a combination of whole-cell patch-clamp recordings and biochemical and molecular biological analyses, we demonstrated that functional ASICs exist in mouse olfactory bulb mitral/tufted (M/T) neurons and mainly consist of homomeric ASIC1a and heteromeric ASIC1a/2a channels. ASIC activation depolarized cultured M/T neurons and increased their intracellular calcium concentration. Thus, ASIC activation may play an important role in normal olfactory function.
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Affiliation(s)
- Ming-Hua Li
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR 97239
| | | | - Koichi Inoue
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | | | - Roger P Simon
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | - Zhi-Gang Xiong
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
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Price MP, Gong H, Parsons MG, Kundert JR, Reznikov LR, Bernardinelli L, Chaloner K, Buchanan GF, Wemmie JA, Richerson GB, Cassell MD, Welsh MJ. Localization and behaviors in null mice suggest that ASIC1 and ASIC2 modulate responses to aversive stimuli. GENES BRAIN AND BEHAVIOR 2013; 13:179-94. [PMID: 24256442 DOI: 10.1111/gbb.12108] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/25/2013] [Accepted: 11/18/2013] [Indexed: 12/21/2022]
Abstract
Acid-sensing ion channels (ASICs) generate H(+) -gated Na(+) currents that contribute to neuronal function and animal behavior. Like ASIC1, ASIC2 subunits are expressed in the brain and multimerize with ASIC1 to influence acid-evoked currents and facilitate ASIC1 localization to dendritic spines. To better understand how ASIC2 contributes to brain function, we localized the protein and tested the behavioral consequences of ASIC2 gene disruption. For comparison, we also localized ASIC1 and studied ASIC1(-/-) mice. ASIC2 was prominently expressed in areas of high synaptic density, and with a few exceptions, ASIC1 and ASIC2 localization exhibited substantial overlap. Loss of ASIC1 or ASIC2 decreased freezing behavior in contextual and auditory cue fear conditioning assays, in response to predator odor and in response to CO2 inhalation. In addition, loss of ASIC1 or ASIC2 increased activity in a forced swim assay. These data suggest that ASIC2, like ASIC1, plays a key role in determining the defensive response to aversive stimuli. They also raise the question of whether gene variations in both ASIC1 and ASIC2 might affect fear and panic in humans.
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Affiliation(s)
- M P Price
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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Krauson AJ, Rued AC, Carattino MD. Independent contribution of extracellular proton binding sites to ASIC1a activation. J Biol Chem 2013; 288:34375-83. [PMID: 24142696 DOI: 10.1074/jbc.m113.504324] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are a group of trimeric cation permeable channels gated by extracellular protons that are mainly expressed in the nervous system. Despite the structural information available for ASIC1, there is limited understanding of the molecular mechanism that allows these channels to sense and respond to drops in extracellular pH. In this report, we employed the substituted cysteine accessibility method and site-directed mutagenesis to examine the mechanism of activation of ASIC1a by extracellular protons. We found that the modification of E238C and D345C channels by MTSET reduced proton apparent affinity for activation. Furthermore, the introduction of positively charged residues at position 345 rendered shifted biphasic proton activation curves. Likewise, channels bearing mutations at positions 79 and 416 in the palm domain of the channel showed reduced proton apparent affinity and biphasic proton activation curves. Of significance, the effect of the mutations at positions 79 and 345 on channel activation was additive. E79K-D345K required a change to a pH lower than 2 for maximal activation. In summary, this study provides direct evidence for the presence of two distinct proton coordination sites in the extracellular region of ASIC1a, which jointly facilitate pore opening in response to extracellular acidification.
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Affiliation(s)
- Aram J Krauson
- From the Division of Renal Electrolytes, Department of Medicine, and
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Abstract
Why do neurons sense extracellular acid? In large part, this question has driven increasing investigation on acid-sensing ion channels (ASICs) in the CNS and the peripheral nervous system for the past two decades. Significant progress has been made in understanding the structure and function of ASICs at the molecular level. Studies aimed at clarifying their physiological importance have suggested roles for ASICs in pain, neurological and psychiatric disease. This Review highlights recent findings linking these channels to physiology and disease. In addition, it discusses some of the implications for therapy and points out questions that remain unanswered.
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Yin T, Lindley TE, Albert GW, Ahmed R, Schmeiser PB, Grady MS, Howard MA, Welsh MJ. Loss of Acid sensing ion channel-1a and bicarbonate administration attenuate the severity of traumatic brain injury. PLoS One 2013; 8:e72379. [PMID: 23991103 PMCID: PMC3753246 DOI: 10.1371/journal.pone.0072379] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 07/09/2013] [Indexed: 12/30/2022] Open
Abstract
Traumatic brain injury (TBI) is a common cause of morbidity and mortality in people of all ages. Following the acute mechanical insult, TBI evolves over the ensuing minutes and days. Understanding the secondary factors that contribute to TBI might suggest therapeutic strategies to reduce the long-term consequences of brain trauma. To assess secondary factors that contribute to TBI, we studied a lateral fluid percussion injury (FPI) model in mice. Following FPI, the brain cortex became acidic, consistent with data from humans following brain trauma. Administering HCO3− after FPI prevented the acidosis and reduced the extent of neurodegeneration. Because acidosis can activate acid sensing ion channels (ASICs), we also studied ASIC1a−/− mice and found reduced neurodegeneration after FPI. Both HCO3− administration and loss of ASIC1a also reduced functional deficits caused by FPI. These results suggest that FPI induces cerebral acidosis that activates ASIC channels and contributes to secondary injury in TBI. They also suggest a therapeutic strategy to attenuate the adverse consequences of TBI.
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Affiliation(s)
- Terry Yin
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Timothy E. Lindley
- Department of Neurosurgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Gregory W. Albert
- Department of Neurosurgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Raheel Ahmed
- Department of Neurosurgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Peter B. Schmeiser
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - M. Sean Grady
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Matthew A. Howard
- Department of Neurosurgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Michael J. Welsh
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurosurgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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45
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Sun YY, Lin SH, Lin HC, Hung CC, Wang CY, Lin YC, Hung KS, Lien CC, Kuan CY, Lee YH. Cell type-specific dependency on the PI3K/Akt signaling pathway for the endogenous Epo and VEGF induction by baicalein in neurons versus astrocytes. PLoS One 2013; 8:e69019. [PMID: 23904909 PMCID: PMC3719842 DOI: 10.1371/journal.pone.0069019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/04/2013] [Indexed: 02/06/2023] Open
Abstract
The neuroprotective effect of baicalein is generally attributed to inhibition of
12/15-lipoxygenase (12/15-LOX) and suppression of oxidative stress, but recent
studies showed that baicalein also activates hypoxia-inducible factor-α (HIF1α)
through inhibition of prolyl hydrolase 2 (PHD2) and activation of the
phosphatidylinositide-3 kinase (PI3K)/Akt signaling pathway. Yet, the
significance and regulation of prosurvival cytokines erythropoietin (Epo) and
vascular endothelial growth factor (VEGF), two transcriptional targets of HIF1α,
in baicalein-mediated neuroprotection in neurons and astrocytes remains unknown.
Here we investigated the causal relationship between the PI3K/Akt signaling
pathway and Epo/VEGF expression in baicalein-mediated neuroprotection in primary
rat cortical neurons and astrocytes. Our results show that baicalein induced Epo
and VEGF expression in a HIF1α- and PI3K/Akt-dependent manner in neurons.
Baicalein also protected neurons against excitotoxicity in a PI3K- and
Epo/VEGF-dependent manner without affecting neuronal excitability. In contrast,
at least a 10-fold higher concentration of baicalein was needed to induce
Epo/VEGF production and PI3K/Akt activity in astrocytes for protection of
neurons. Moreover, only baicalein-induced astrocytic VEGF, but not Epo
expression requires HIF1α, while PI3K/Akt signaling had little role in
baicalein-induced astrocytic Epo/VEGF expression. These results suggest distinct
mechanisms of baicalein-mediated Epo/VEGF production in neurons and astrocytes
for neuroprotection, and provide new insights into the mechanisms and potential
of baicalein in treating brain injury in vivo.
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Affiliation(s)
- Yu-Yo Sun
- Division of Neurology, Department of Pediatrics, the Center for
Neurodegenerative Disease, Emory University School of Medicine, Atlanta,
Georgia, United States of America
| | - Shang-Hsuan Lin
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
| | - Hung-Cheng Lin
- Graduate Institute of Medical Sciences, Taipei Medical University,
Taipei, Taiwan
| | - Chia-Chi Hung
- Graduate Institute of Medical Sciences, Taipei Medical University,
Taipei, Taiwan
| | - Chen-Yu Wang
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
| | - Yen-Chu Lin
- Institute of Neuroscience, National Yang-Ming University, Taipei,
Taiwan
| | - Kuo-Sheng Hung
- Department of Neurosurgery, Taipei Medical University Wan Fang Hospital,
Taipei, Taiwan
| | - Cheng-Chang Lien
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
- Institute of Neuroscience, National Yang-Ming University, Taipei,
Taiwan
| | - Chia-Yi Kuan
- Division of Neurology, Department of Pediatrics, the Center for
Neurodegenerative Disease, Emory University School of Medicine, Atlanta,
Georgia, United States of America
| | - Yi-Hsuan Lee
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
- * E-mail:
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Acid-sensing ion channel-1a is not required for normal hippocampal LTP and spatial memory. J Neurosci 2013; 33:1828-32. [PMID: 23365222 DOI: 10.1523/jneurosci.4132-12.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Acid-sensing ion channel-1a (ASIC1a) is localized in brain regions with high synaptic density and is thought to contribute to synaptic plasticity, learning, and memory. A prominent hypothesis is that activation of postsynaptic ASICs promotes depolarization, thereby augmenting N-methyl-d-aspartate receptor function and contributing to the induction of long-term potentiation (LTP). However, evidence for activation of postsynaptic ASICs during neurotransmission has not been established. Here, we re-examined the role of ASIC1a in LTP in the hippocampus using pharmacological and genetic approaches. Our results showed that a tarantula peptide psalmotoxin, which profoundly blocked ASIC currents in the hippocampal neurons, had no effect on LTP. Similarly, normal LTP was robustly generated in ASIC1a-null mice. A further behavioral analysis showed that mice lacking ASIC1a had normal performance in hippocampus-dependent spatial memory. In summary, our results indicate that ASIC1a is not required for hippocampal LTP and spatial memory. We therefore propose that the role of ASIC1a in LTP and spatial learning should be reassessed.
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47
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Zha XM. Acid-sensing ion channels: trafficking and synaptic function. Mol Brain 2013; 6:1. [PMID: 23281934 PMCID: PMC3562204 DOI: 10.1186/1756-6606-6-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 12/20/2012] [Indexed: 01/05/2023] Open
Abstract
Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.
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Affiliation(s)
- Xiang-ming Zha
- Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, 307 University Blvd, MSB1201, Mobile, AL 36688, USA.
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48
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Li T, Yang Y, Canessa CM. Impact of recovery from desensitization on acid-sensing ion channel-1a (ASIC1a) current and response to high frequency stimulation. J Biol Chem 2012; 287:40680-9. [PMID: 23048040 DOI: 10.1074/jbc.m112.418400] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Consecutive proton stimulation reduces ASIC1a peak currents leading to silencing of channels. RESULTS Kinetic analysis using a fast perfusion system shows that human ASIC1a has two desensitized states with markedly different stabilities. CONCLUSION High frequency trains of short stimuli prevent desensitization. SIGNIFICANCE The results predict steady ASIC1a responses to high frequency release of protons as in synaptic transmission. ASIC1a is a neuronal sodium channel activated by external H(+) ions. To date, all the characterization of ASIC1a has been conducted applying long H(+) stimuli lasting several seconds. Such experimental protocols weaken and even silence ASIC1a currents to repetitive stimulation. In this work, we examined ASIC1a currents by methods that use rapid application and removal of H(+). We found that brief H(+) stimuli, <100 ms, even if applied at high frequency, prevent desensitization thereby generate full and steady peak currents of human ASIC1a. Kinetic analysis of recovery from desensitization of hASIC1a revealed two desensitized states: short- and long-lasting with time constants of τ(Ds) ≤0.5 and τ(Dl) = 229 s, while in chicken ASIC1a the two desensitized states have similar values τ(D) 4.5 s. It is the large difference in stability of the two desensitized states that makes hASIC1a desensitization more pronounced and complex than in cASIC1a. Furthermore, recovery from desensitization was unrelated to cytosolic variations in pH, ATP, PIP(2), or redox state but was dependent on the hydrophobicity of key residues in the first transmembrane segment (TM1). In conclusion, brief H(+)-stimuli maintain steady the magnitude of peak currents thereby the ASIC1a channel is well poised to partake in high frequency signals in the brain.
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Affiliation(s)
- Tianbo Li
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520-8026, USA
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Chu XP, Xiong ZG. Physiological and pathological functions of acid-sensing ion channels in the central nervous system. Curr Drug Targets 2012; 13:263-71. [PMID: 22204324 DOI: 10.2174/138945012799201685] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/08/2011] [Accepted: 08/12/2011] [Indexed: 12/20/2022]
Abstract
Protons are important signals for neuronal function. In the central nervous system (CNS), proton concentrations change locally when synaptic vesicles release their acidic contents into the synaptic cleft, and globally in ischemia, seizures, traumatic brain injury, and other neurological disorders due to lactic acid accumulation. The finding that protons gate a distinct family of ion channels, the acid-sensing ion channels (ASICs), has shed new light on the mechanism of acid signaling and acidosis-associated neuronal injury. Accumulating evidence has suggested that ASICs play important roles in physiological processes such as synaptic plasticity, learning/memory, fear conditioning, and retinal integrity, and in pathological conditions such as brain ischemia, multiple sclerosis, epileptic seizures, and malignant glioma. Thus, targeting these channels may lead to novel therapeutic interventions for neurological disorders. The goal of this review is to provide an update on recent advances in our understanding of the functions of ASICs in the CNS.
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Affiliation(s)
- Xiang-Ping Chu
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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Huda R, Pollema-Mays SL, Chang Z, Alheid GF, McCrimmon DR, Martina M. Acid-sensing ion channels contribute to chemosensitivity of breathing-related neurons of the nucleus of the solitary tract. J Physiol 2012; 590:4761-75. [PMID: 22890703 DOI: 10.1113/jphysiol.2012.232470] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cellular mechanisms of central pH chemosensitivity remain largely unknown. The nucleus of the solitary tract (NTS) integrates peripheral afferents with central pathways controlling breathing; NTS neurons function as central chemosensors, but only limited information exists concerning the ionic mechanisms involved. Acid-sensing ion channels (ASICs) mediate chemosensitivity in nociceptive terminals, where pH values ∼6.5 are not uncommon in inflammation, but are also abundantly expressed throughout the brain where pHi s tightly regulated and their role is less clear. Here we test the hypothesis that ASICs are expressed in NTS neurons and contribute to intrinsic chemosensitivity and control of breathing. In electrophysiological recordings from acute rat NTS slices, ∼40% of NTS neurons responded to physiological acidification (pH 7.0) with a transient depolarization. This response was also present in dissociated neurons suggesting an intrinsic mechanism. In voltage clamp recordings in slices, a pH drop from 7.4 to 7.0 induced ASIC-like inward currents (blocked by 100 μM amiloride) in ∼40% of NTS neurons, while at pH ≤ 6.5 these currents were detected in all neurons tested; RT-PCR revealed expression of ASIC1 and, less abundantly, ASIC2 in the NTS. Anatomical analysis of dye-filled neurons showed that ASIC-dependent chemosensitive cells (cells responding to pH 7.0) cluster dorsally in the NTS. Using in vivo retrograde labelling from the ventral respiratory column, 90% (9/10) of the labelled neurons showed an ASIC-like response to pH 7.0, suggesting that ASIC currents contribute to control of breathing. Accordingly, amiloride injection into the NTS reduced phrenic nerve activity of anaesthetized rats with an elevated arterial P(CO(2)) .
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Affiliation(s)
- Rafiq Huda
- Department of Physiology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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