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Chen L, Hu J, Mu J, Li C, Wu GY, He C, Xie Y, Ye JN. Specific stimulation of PV + neurons at early stage ameliorates prefrontal ischemia-induced spatial working memory impairment. Behav Brain Res 2021; 414:113511. [PMID: 34358569 DOI: 10.1016/j.bbr.2021.113511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022]
Abstract
Prefrontal ischemia can cause impairments in learning and memory, executive functions and cognitive flexibility. However, the related cellular mechanisms at the early stage are still elusive. The present study used ischemic stroke in medial prefrontal cortex and systemically investigated the electrophysiological changes of the parvalbumin (PV+) interneurons 12 h post ischemia. We found that Ih and the related voltage sags in PV+ interneurons are downregulated post ischemia, which correlates with hyperpolarization of the membrane potentials and increased input resistance in these interneurons. Consistent with the suppression of Ih, postischemic PV+ interneurons exhibited a reduction in excitability and exerted a less inhibitory control over the neighboring pyramidal excitatory neurons. Moreover, we found that specifically chemogenetic activation of PV+ neurons at early stage ameliorated prefrontal ischemia-induced spatial working memory dysfunction in T-maze without effects on the locomotor coordination and balance. In contrast, suppression of PV+ neurons by blockade of Ih leaded to further aggravate the damage of spatial memory. These findings indicate that dysfunctional Ih in the PV+ neuron postischemia induces the imbalance of excitation and inhibition, which might represent a novel mechanism underlying the prefrontal ischemia-induced cognitive impairment.
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Affiliation(s)
- Lin Chen
- Department of Histology and Embryology, Third Military Medical University, Chongqing 400038, PR China
| | - Jun Hu
- Department of Neurology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China
| | - Jiankun Mu
- The Affiliated Rehabilitation Hospital of Chongqing Medical University, Chongqing 400036, PR China
| | - Chao Li
- Department of Neurology, The General Hospital of Western Theater Command, No.270 Rongdu Avenue, Jinniu District, Chengdu 610083, Sichuan Province, PR China
| | - Guang-Yan Wu
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, PR China
| | - Chao He
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400037, PR China
| | - Youhong Xie
- The Affiliated Rehabilitation Hospital of Chongqing Medical University, Chongqing 400036, PR China
| | - Jian-Ning Ye
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, PR China.
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Rabiller G, He JW, Nishijima Y, Wong A, Liu J. Perturbation of Brain Oscillations after Ischemic Stroke: A Potential Biomarker for Post-Stroke Function and Therapy. Int J Mol Sci 2015; 16:25605-40. [PMID: 26516838 PMCID: PMC4632818 DOI: 10.3390/ijms161025605] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/06/2015] [Accepted: 10/15/2015] [Indexed: 01/08/2023] Open
Abstract
Brain waves resonate from the generators of electrical current and propagate across brain regions with oscillation frequencies ranging from 0.05 to 500 Hz. The commonly observed oscillatory waves recorded by an electroencephalogram (EEG) in normal adult humans can be grouped into five main categories according to the frequency and amplitude, namely δ (1-4 Hz, 20-200 μV), θ (4-8 Hz, 10 μV), α (8-12 Hz, 20-200 μV), β (12-30 Hz, 5-10 μV), and γ (30-80 Hz, low amplitude). Emerging evidence from experimental and human studies suggests that groups of function and behavior seem to be specifically associated with the presence of each oscillation band, although the complex relationship between oscillation frequency and function, as well as the interaction between brain oscillations, are far from clear. Changes of brain oscillation patterns have long been implicated in the diseases of the central nervous system including ischemic stroke, in which the reduction of cerebral blood flow as well as the progression of tissue damage have direct spatiotemporal effects on the power of several oscillatory bands and their interactions. This review summarizes the current knowledge in behavior and function associated with each brain oscillation, and also in the specific changes in brain electrical activities that correspond to the molecular events and functional alterations observed after experimental and human stroke. We provide the basis of the generations of brain oscillations and potential cellular and molecular mechanisms underlying stroke-induced perturbation. We will also discuss the implications of using brain oscillation patterns as biomarkers for the prediction of stroke outcome and therapeutic efficacy.
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Affiliation(s)
- Gratianne Rabiller
- Department of Neurological Surgery, University of California at San Francisco and Department of Veterans Affairs Medical Center, 1700 Owens Street, San Francisco, CA 94158, USA.
- UCSF and SFVAMC, San Francisco, CA 94158, USA.
- Univ. de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux 33000, France.
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux 33000, France.
| | - Ji-Wei He
- Department of Neurological Surgery, University of California at San Francisco and Department of Veterans Affairs Medical Center, 1700 Owens Street, San Francisco, CA 94158, USA.
- UCSF and SFVAMC, San Francisco, CA 94158, USA.
| | - Yasuo Nishijima
- Department of Neurological Surgery, University of California at San Francisco and Department of Veterans Affairs Medical Center, 1700 Owens Street, San Francisco, CA 94158, USA.
- UCSF and SFVAMC, San Francisco, CA 94158, USA.
- Department of Neurosurgery, Tohoku University Graduate School of Medicine 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
| | - Aaron Wong
- Department of Neurological Surgery, University of California at San Francisco and Department of Veterans Affairs Medical Center, 1700 Owens Street, San Francisco, CA 94158, USA.
- UCSF and SFVAMC, San Francisco, CA 94158, USA.
- Rice University, 6100 Main St, Houston, TX 77005, USA.
| | - Jialing Liu
- Department of Neurological Surgery, University of California at San Francisco and Department of Veterans Affairs Medical Center, 1700 Owens Street, San Francisco, CA 94158, USA.
- UCSF and SFVAMC, San Francisco, CA 94158, USA.
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Bista P, Cerina M, Ehling P, Leist M, Pape HC, Meuth SG, Budde T. The role of two-pore-domain background K⁺ (K₂p) channels in the thalamus. Pflugers Arch 2014; 467:895-905. [PMID: 25346156 DOI: 10.1007/s00424-014-1632-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 12/15/2022]
Abstract
The thalamocortical system is characterized by two fundamentally different activity states, namely synchronized burst firing and tonic action potential generation, which mainly occur during the behavioral states of sleep and wakefulness, respectively. The switch between the two firing modes is crucially governed by the bidirectional modulation of members of the K2P channel family, namely tandem of P domains in a weakly inward rectifying K(+) (TWIK)-related acid-sensitive K(+) (TASK) and TWIK-related K(+) (TREK) channels, in thalamocortical relay (TC) neurons. Several physicochemical stimuli including neurotransmitters, protons, di- and multivalent cations as well as clinically used drugs have been shown to modulate K2P channels in these cells. With respect to modulation of these channels by G-protein-coupled receptors, PLCβ plays a unique role with both substrate breakdown and product synthesis exerting important functions. While the degradation of PIP2 leads to the closure of TREK channels, the production of DAG induces the inhibition of TASK channels. Therefore, TASK and TREK channels were found to be central elements in the control of thalamic activity modes. Since research has yet focused on identifying the muscarinic pathway underling the modulation of TASK and TREK channels in TC neurons, future studies should address other thalamic cell types and members of the K2P channel family.
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Affiliation(s)
- Pawan Bista
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, 48149, Münster, Germany
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Ehling P, Göb E, Bittner S, Budde T, Ludwig A, Kleinschnitz C, Meuth SG. Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice? EXPERIMENTAL & TRANSLATIONAL STROKE MEDICINE 2013; 5:16. [PMID: 24373160 PMCID: PMC3879998 DOI: 10.1186/2040-7378-5-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 12/22/2013] [Indexed: 01/06/2023]
Abstract
Background Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium (K2P) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing K+ leak currents, and the pacemaker channel HCN2, carrying depolarizing Ih, stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts. Methods In C57Bl/6 (wildtype, WT), hcn2+/+ and hcn2-/- mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays. Results After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups. Conclusions Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model.
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Affiliation(s)
- Petra Ehling
- Department of Neurology, and Institute of Physiology, Neuropathophysiology, Albert-Schweitzer-Campus 1, Westfälische Wilhelms University, 48149 Münster, Germany.,Department of Neurology, ICB, Mendelstr. 7, 48149 Münster, Germany
| | - Eva Göb
- Department of Neurology, University Clinic Würzburg, Josef-Schneider-Str. 11, Würzburg, Germany
| | - Stefan Bittner
- Department of Neurology, Albert-Schweitzer-Campus 1, Westfälische Wilhelms University, Münster, Germany
| | - Thomas Budde
- Institute of Physiology I, Westfälische Wilhelms University, Robert-Koch-Str. 27a, Münster, Germany
| | - Andreas Ludwig
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander Universität Erlangen-Nürnberg, Fahrstr. 17, Erlangen, Germany
| | - Christoph Kleinschnitz
- Department of Neurology, University Clinic Würzburg, Josef-Schneider-Str. 11, Würzburg, Germany
| | - Sven G Meuth
- Department of Neurology, and Institute of Physiology, Neuropathophysiology, Albert-Schweitzer-Campus 1, Westfälische Wilhelms University, 48149 Münster, Germany.,Department of Neurology, Albert-Schweitzer-Campus 1, Westfälische Wilhelms University, Münster, Germany
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Brisson CD, Lukewich MK, Andrew RD. A distinct boundary between the higher brain's susceptibility to ischemia and the lower brain's resistance. PLoS One 2013; 8:e79589. [PMID: 24223181 PMCID: PMC3819273 DOI: 10.1371/journal.pone.0079589] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 10/03/2013] [Indexed: 11/19/2022] Open
Abstract
Higher brain regions are more susceptible to global ischemia than the brainstem, but is there a gradual increase in vulnerability in the caudal-rostral direction or is there a discrete boundary? We examined the interface between `higher` thalamus and the hypothalamus the using live brain slices where variation in blood flow is not a factor. Whole-cell current clamp recording of 18 thalamic neurons in response to 10 min O2/glucose deprivation (OGD) revealed a rapid anoxic depolarization (AD) from which thalamic neurons do not recover. Newly acquired neurons could not be patched following AD, confirming significant regional thalamic injury. Coinciding with AD, light transmittance (LT) imaging during whole-cell recording showed an elevated LT front that initiated in midline thalamus and that propagated into adjacent hypothalamus. However, hypothalamic neurons patched in paraventricular nucleus (PVN, n= 8 magnocellular and 12 parvocellular neurons) and suprachiasmatic nucleus (SCN, n= 18) only slowly depolarized as AD passed through these regions. And with return to control aCSF, hypothalamic neurons repolarized and recovered their input resistance and action potential amplitude. Moreover, newly acquired hypothalamic neurons could be readily patched following exposure to OGD, with resting parameters similar to neurons not previously exposed to OGD. Thalamic susceptibility and hypothalamic resilience were also observed following ouabain exposure which blocks the Na+/K+ pump, evoking depolarization similar to OGD in all neuronal types tested. Finally, brief exposure to elevated [K+]o caused spreading depression (SD, a milder, AD-like event) only in thalamic neurons so SD generation is regionally correlated with strong AD. Therefore the thalamus-hypothalamus interface represents a discrete boundary where neuronal vulnerability to ischemia is high in thalamus (like more rostral neocortex, striatum, hippocampus). In contrast hypothalamic neurons are comparatively resistant, generating weaker and recoverable anoxic depolarization similar to brainstem neurons, possibly the result of a Na/K pump that better functions during ischemia.
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Affiliation(s)
- C. Devin Brisson
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Mark K. Lukewich
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - R. David Andrew
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- * E-mail:
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Post-anesthetic cortical blindness in cats: Twenty cases. Vet J 2012; 193:367-73. [DOI: 10.1016/j.tvjl.2012.01.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 01/18/2012] [Accepted: 01/26/2012] [Indexed: 11/20/2022]
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Krnjević K. Electrophysiology of cerebral ischemia. Neuropharmacology 2008; 55:319-33. [DOI: 10.1016/j.neuropharm.2008.01.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 12/31/2007] [Accepted: 01/08/2008] [Indexed: 12/20/2022]
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Deng P, Zhang Y, Xu ZC. Inhibition of Ih in striatal cholinergic interneurons early after transient forebrain ischemia. J Cereb Blood Flow Metab 2008; 28:939-47. [PMID: 18000510 DOI: 10.1038/sj.jcbfm.9600583] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Striatal cholinergic interneurons are relatively resistant to ischemic insults. These neurons express hyperpolarization-activated cation current (I(h)) that profoundly regulates neuronal excitability. Changes in neuronal excitability early after ischemia may be crucial for determining neuronal injury. Here we report that I(h) in cholinergic interneurons was decreased 3 h after transient forebrain ischemia, which was accompanied by a negative shift of the voltage dependence of activation. The inhibition of I(h) might be due to the tonic activation of adenosine A1 receptors, as blockade of A1 receptors significantly increased I(h) in postischemic neurons, but had no effect on control neurons. Consistent with the inhibition of I(h), postischemic neurons showed a reduction in both spontaneous firing and hyperpolarization-induced rebound depolarization. These findings indicate that I(h) may play excitatory roles in striatal cholinergic interneurons. Postischemic inhibition of I(h) might be a novel mechanism by which adenosine confers neuronal resistance to cerebral ischemia.
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Affiliation(s)
- Ping Deng
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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9
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Abstract
All mammals and birds must develop effective strategies to cope with reduced oxygen availability. These animals achieve tolerance to acute and chronic hypoxia by (a) reductions in metabolism, (b) the prevention of cellular injury, and (c) the maintenance of functional integrity. Failure to meet any one of these tasks is detrimental. Birds and mammals accomplish this triple task through a highly coordinated, systems-level reconfiguration involving the partial shutdown of some but not all organs. This reconfiguration is achieved through a similarly complex reconfiguration at the cellular and molecular levels. Reconfiguration at these various levels depends on numerous factors that include the environment, the degree of hypoxic stress, and developmental, behavioral, and ecological conditions. Although common molecular strategies exist, the cellular and molecular changes in any given cell are very diverse. Some cells remain metabolically active, whereas others shut down or rely on anaerobic metabolism. This cellular shutdown is temporarily regulated, and during hypoxic exposure, active cellular networks must continue to control vital functions. The challenge for future research is to explore the cellular mechanisms and conditions that transform an organ or a cellular network into a hypometabolic state, without loss of functional integrity. Much can be learned in this respect from nature: Diving, burrowing, and hibernating animals living in diverse environments are masters of adaptation and can teach us how to deal with hypoxia, an issue of great clinical significance.
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Affiliation(s)
- Jan-Marino Ramirez
- Department of Organismal Biology & Anatomy, University of Chicago, Chicago, Illinois 60637, USA.
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Meuth SG, Kanyshkova T, Meuth P, Landgraf P, Munsch T, Ludwig A, Hofmann F, Pape HC, Budde T. Membrane Resting Potential of Thalamocortical Relay Neurons Is Shaped by the Interaction Among TASK3 and HCN2 Channels. J Neurophysiol 2006; 96:1517-29. [PMID: 16760342 DOI: 10.1152/jn.01212.2005] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
By combining molecular biological, electrophysiological, immunological, and computer modeling techniques, we here demonstrate a counterbalancing contribution of TASK channels, underlying hyperpolarizing K+ leak currents, and HCN channels, underlying depolarizing Ih, to the resting membrane potential of thalamocortical relay (TC) neurons. RT-PCR experiments revealed the expression of TASK1, TASK3, and HCN1–4. Quantitative determination of mRNA expression levels and immunocytochemical staining demonstrated that TASK3 and HCN2 channels represent the dominant thalamic isoforms and are coexpressed in TC neurons. Extracellular acidification, a standard procedure to inhibit TASK channels, blocked a TASK current masked by additional action on HCN channels. Only in the presence of the HCN blocker ZD7288 was the pH-sensitive component typical for a TASK current, i.e., outward rectification and current reversal at the K+ equilibrium potential. In a similar way extracellular acidification was able to shift the activity pattern of TC neurons from burst to tonic firing only during block of Ih or genetic knock out of HCN channels. A single compartmental computer model of TC neurons simulated the counterbalancing influence of TASK and HCN on the resting membrane potential. It is concluded that TASK3 and HCN2 channels stabilize the membrane potential by a mutual functional interaction, that the most efficient way to regulate the membrane potential of TC neurons is the converse modulation of TASK and HCN channels, and that TC neurons are potentially more resistant to insults accompanied by extracellular pH shifts in comparison to other CNS regions.
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Affiliation(s)
- Sven G Meuth
- Neurologische Klinik, Bayerische Julius-Maximilians-Universität, Würzburg, Germany
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Tsuboi Y, Takeda M, Tanimoto T, Ikeda M, Matsumoto S, Kitagawa J, Teramoto K, Simizu K, Yamazaki Y, Shima A, Ren K, Iwata K. Alteration of the second branch of the trigeminal nerve activity following inferior alveolar nerve transection in rats. Pain 2004; 111:323-334. [PMID: 15363876 DOI: 10.1016/j.pain.2004.07.014] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2004] [Revised: 05/31/2004] [Accepted: 07/12/2004] [Indexed: 12/31/2022]
Abstract
After transection of the inferior alveolar nerve (IAN), the whisker pad area, which is innervated by the infraorbital nerve (ION) that was not injured, showed hypersensitivity to mechanical stimulation. Two days after IAN transection, threshold intensity for escape behavior to mechanical stimulation of the ipsilateral whisker pad area was less than 4.0 g, indicating mechanical allodynia. A total of 68 single fiber discharges were recorded from ION fibers at 3 days after IAN transection. The responses of C- and A-fibers were classified according to their conduction velocity. The C-fiber activities were not affected by IAN transection, whereas A-fiber activities were significantly enhanced by IAN transection as indicated by an increase in background activity and mechanically evoked response. Since the A-fiber responses were significantly affected by IAN transection, patch clamp recording was performed from middle to large diameter retrogradely labeled and acutely dissociated trigeminal ganglion (TRG) neurons. The I(K) (sustained) and I(A) (transient) currents were significantly smaller and hyperpolarization-activated current (I(h)) was significantly larger in TRG neurons of rats with IAN transection as compared to those of naive rats. Furthermore, current injection into TRG neurons induced high frequency spike discharges in rats with IAN transection. These data suggest that changes in K(+) current and I(h) observed in the uninjured TRG neurons reflect an increase in excitability of TRG neurons innervated by the ION after IAN transection, resulting in the development of mechano-allodynia in the area adjacent to the injured IAN innervated region.
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Affiliation(s)
- Yoshiyuki Tsuboi
- Department of Physiology, School of Dentistry, Nihon University, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan Department of Physiology, School of Dentistry at Tokyo, Nippon Dental University, 1-9-20, Fujimi-cho, Chiyoda-ku, Tokyo 102-8159, Japan Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Dysphagia Rehabilitation, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Dental Anesthesiology, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Biomedical Sciences, University of Maryland Dental School, Baltimore, MD 21201, USA Division of Applied System Neuroscience Advanced Medical Research Center, Nihon University Graduate School of Medical Science, 30-1 Ohyaguchi-Kamimachi Itabashi, Tokyo 173-8610, Japan
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Chen K, Aradi I, Santhakumar V, Soltesz I. H-channels in epilepsy: new targets for seizure control? Trends Pharmacol Sci 2002; 23:552-7. [PMID: 12457772 DOI: 10.1016/s0165-6147(02)02110-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Hyperpolarization-activated cation channels (h-channels) are key regulators of neuronal excitation and inhibition, and have a rich diversity of subunit composition, distribution, modulation and function. Recent results indicate that the behavior of h-channels can be altered significantly by seizures. The activity-dependent, short-term and long-term plasticity of h-channels can, in turn, modulate neuronal excitability. The reciprocal interactions between neuronal activity and h-channels indicate that these ion channels could be promising novel targets for anti-epileptic therapies.
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Affiliation(s)
- Kang Chen
- Dept of Anatomy & Neurobiology, University of California Irvine, 92697-1280, USA
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Fleidervish IA, Gebhardt C, Astman N, Gutnick MJ, Heinemann U. Enhanced spontaneous transmitter release is the earliest consequence of neocortical hypoxia that can explain the disruption of normal circuit function. J Neurosci 2001; 21:4600-8. [PMID: 11425888 PMCID: PMC6762367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
After the onset of an acute episode of arrested circulation to the brain and consequent cerebral hypoxia, EEG changes and modifications of consciousness ensue within seconds. This in part reflects the rapid effect of hypoxia on the neocortex, where oxygen deprivation leads to impaired neuronal excitability and abnormal synaptic transmission. To identify the cellular mechanisms responsible for the earliest changes in neocortical function and to determine their time course, we have used patch-in-slice recording techniques to investigate the effects of acute hypoxia on the synaptic and intrinsic properties of layer 5 neurons. Coronal slices of mouse somatosensory cortex were maintained at 37 degrees C and challenged with episodes of hypoxia (3-4 min of exposure to 95% N(2), 5% CO(2)). In recordings with cell-attached patch electrodes, activation of ATP-sensitive potassium channels first became detectable 211 +/- 11 sec (range, 185-240 sec; n = 6 patches) after the onset of hypoxia. Similar recording techniques revealed no alterations in the properties of Na(+) currents in the first 4 min after the onset of hypoxia. The earliest hypoxia-induced disturbance was a marked increase in the frequency of spontaneous EPSCs and IPSCs, which began within 15-30 sec of the removal of oxygen. This rapid synaptic effect was not sensitive to TTX and was present in Ca(2+)-free perfusate, indicating that the hypoxia had a direct influence on the vesicular release mechanisms. The incoherent, massive increase in miniature PSCs would be expected to deplete the readily releasable pool of vesicles in cortical terminals, and to thereby markedly distort the neuronal interactions that underlie normal circuit function.
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Affiliation(s)
- I A Fleidervish
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel 76100.
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Thoby-Brisson M, Ramirez JM. Role of inspiratory pacemaker neurons in mediating the hypoxic response of the respiratory network in vitro. J Neurosci 2000; 20:5858-66. [PMID: 10908629 PMCID: PMC6772549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
In severe hypoxia the breathing frequency is modulated in a biphasic manner: an initial increase (augmentation) is followed by a depression and cessation of breathing (apnea). Using a mouse slice preparation that contains the functional respiratory network, we aimed at identifying the neurons responsible for this frequency modulation. Whole-cell patch recordings revealed that expiratory neurons become tonically active during anoxia, indicating that these neurons cannot be responsible for the respiratory frequency modulation. Inspiratory neurons tended to depolarize (by 6.9 mV; n = 9), and the frequency of rhythmic activity was significantly increased during anoxia (from 0.16 to 0.4 Hz; n = 9). After the blockade of network activity with 6-cyano-7-nitroquinoxaline-2, 3-dione, most inspiratory neurons became tonically active (72%; n = 25, non-pacemaker). In anoxia, the membrane potential of these non-pacemaker neurons did not change (-0.26 mV; n = 6), and their tonic activity ceased. Only a subpopulation of inspiratory neurons remained rhythmically active in the absence of network activity (pacemaker neurons, 28%, 7 of 25 inspiratory neurons). In anoxia two subgroups of pacemaker neurons were differentiated; one group showed a transient increase in the bursting activity, followed by a decrease and cessation of rhythmic activity. These neurons tended to depolarize (by 10.3 mV) during anoxia. The second group remained rhythmic during the entire anoxic exposure and exhibited no depolarization. The time course of the frequency modulation in all pacemaker neurons resembled that of the intact network. We conclude that pacemaker neurons are primarily responsible for the frequency modulation in anoxia and that in the respiratory network there is a strict separation between rhythm- and pattern-generating mechanisms.
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Affiliation(s)
- M Thoby-Brisson
- Department of Organismal Biology and Anatomy, Committee on Neurobiology, The University of Chicago, IL 60637, USA
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Mazza E, Edelman NH, Neubauer JA. Hypoxic excitation in neurons cultured from the rostral ventrolateral medulla of the neonatal rat. J Appl Physiol (1985) 2000; 88:2319-29. [PMID: 10846051 DOI: 10.1152/jappl.2000.88.6.2319] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons within cardiorespiratory regions of the rostral ventrolateral medulla (RVLM) have been shown to be excited by local hypoxia. To determine the electrophysiological properties of these excitatory responses to hypoxia, we developed a primary dissociated cell culture system to examine the intrinsic response of RVLM neurons to hypoxia. Neonatal rat neurons plated on medullary astrocyte monolayers were studied using the whole cell perforated patch-clamp technique. Sodium cyanide (NaCN, 0.5-10 mM) was used, and membrane potential (V(m)), firing frequency, and input resistance were examined. In 11 of 19 neurons, NaCN produced a V(m) depolarization, an increase in firing frequency, and a decrease in input resistance, suggesting the opening of a cation channel. The hypoxic depolarization had a linear dose response and was dependent on baseline V(m), with a greater response at more hyperpolarized V(m). In 8 of 19 neurons, NaCN produced a V(m) hyperpolarization, decrease in firing frequency, and variable changes in input resistance. The V(m) hyperpolarization exhibited an all-or-none dose response and was independent of baseline V(m). These differential responses to NaCN were retained after synaptic blockade with low Ca(2+)-high Mg(2+) or TTX. Thus hypoxic excitation 1) is maintained in cell culture, 2) is an intrinsic response, and 3) is likely due to the increase in a cation current. These hypoxia-excited neurons are likely candidates to function as central oxygen sensors.
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Affiliation(s)
- E Mazza
- Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, NJ 08903-0019, USA
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Erdemli G, Crunelli V. Release of monoamines and nitric oxide is involved in the modulation of hyperpolarization-activated inward current during acute thalamic hypoxia. Neuroscience 2000; 96:565-74. [PMID: 10717436 DOI: 10.1016/s0306-4522(99)00602-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Using slices of the dorsal lateral geniculate nucleus, it has been shown that, in the presence of excitatory and inhibitory amino acid antagonists, brief periods of hypoxia (3-4 min of 95% N(2)/5% CO(2)) induce in thalamocortical neurons an increase in instantaneous input conductance (G(N)) accompanied by an inward shift in baseline holding current (I(BH)). These effects have been suggested to be mediated, at least in part, by a positive shift in the voltage-dependence of the hyperpolarization-activated, mixed Na(+)/K(+) current (I(h)) and a change in its activation kinetics which transforms it into an almost instantaneously activated current. In this study, using the whole-cell patch-clamp technique, the contribution of an increased Ca(2+)-dependent transmitter release to the hypoxic response of thalamocortical neurons was further investigated using (i) blockers of calcineurin, a Ca(2+)/calmodulin-activated phosphatase that selectively regulates Ca(2+)-dependent release, and (ii) antagonists of neurotransmitters that are known to modulate I(h). Thalamocortical neurons (n = 23) recorded with electrodes filled with calcineurin autoinhibitory fragment (30-250 microM), a membrane impermeable blocker of calcinuerin, showed no difference either in resting, or in the hypoxia-induced changes in, G(N), I(BH) and I(h), when compared to thalamocortical cells patched with electrodes that did not contain calcineurin autoinhibitory fragment. In contrast, in 18 of these neurons recorded with calcineurin autoinhibitory fragment-filled electrodes, bath application either of cyclosporin-A (20 microM) or tacrolimus (50-100 microM), two membrane permeable blockers of calcineurin, abolished the effects of hypoxia on G(N), I(BH), and I(h). Separate application of noradrenaline, serotonin, histamine and nitric oxide antagonists produced only a small depression of the hypoxic response, while concomitant bath application of these antagonists decreased the hypoxia-induced changes in G(N) and I(BH) by 55 and 42%, respectively (n = 12). Concomitant bath application of 8-bromo-adenosine-3'5'-cyclicmonophosphate and 8-bromo-guanosine-3'5'-cyclicmonophosphate (both 1mM), which are known to mediate the action of these transmitters on I(h), increased G(N) (40%), decreased I(h) time-constant of activation (30%) and significantly occluded (50%) the hypoxia-induced effect on G(N) and I(BH). Thalamocortical neurons (n = 6) patched with electrodes filled with 8-bromo-adenosine-3'5'-cyclicmonophosphate and 8-bromo-guanosine-3'5'-cyclicmonophosphate (both 1 mM) showed a larger G(N) than the one recorded with the standard internal solution, and a significant depression of the hypoxia-induced changes in G(N) and I(BH). These results indicate that during acute thalamic hypoxia an increased release of noradrenaline, serotonin, histamine and nitric oxide is responsible for transforming I(h) into an instantaneously activating current via cyclic AMP- and cyclic GMP-mediated mechanisms.
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Affiliation(s)
- G Erdemli
- School of Biosciences, Cardiff University, Museum Avenue, PO Box 911, Cardiff, UK
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Mironov SL, Langohr K, Richter DW. Hyperpolarization-activated current, Ih, in inspiratory brainstem neurons and its inhibition by hypoxia. Eur J Neurosci 2000; 12:520-6. [PMID: 10712631 DOI: 10.1046/j.1460-9568.2000.00928.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A hyperpolarization-activated current, Ih, is often implied in pacemaker-like depolarizations during rhythmic oscillatory activity. We describe Ih in the isolated respiratory centre of immature mice (P6-P11). Ih was recorded in 15% (22/146) of all inspiratory neurons examined. The mean half-maximal Ih activation occurred at -78 mV and the reversal potential was -40 mV. Ih was inhibited by Cs+ (1-5 mM) and by organic blockers N-ethyl-1,6-dihydro-1, 2-dimethyl-6-(methylimino)-N-phenyl-4-pyrimidinamine (ZD 7288; 0.3-3 microM) and N,N'-bis-(3,4-dimethylphenylethyl)-N-methylamine (YS 035, 3-30 microM), but not by Ba2+ (0.5 mM). The organic Ih blockers did not change the inspiratory bursts recorded from the XIIth nerve and synaptic drives in inspiratory neurons. Hypoxia reversibly inhibited Ih but, in the presence of organic blockers, the hypoxic reaction remained unchanged. We conclude that although Ih channels are functional in a minority of inspiratory neurons, Ih does not contribute to respiratory rhythm generation or its modulation by hypoxia.
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Affiliation(s)
- S L Mironov
- II Department of Physiology, University of Göttingen, Humboldtallee 23, Göttingen 37073, Germany.
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