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Rychlik N, Hundehege P, Budde T. Influence of inflammatory processes on thalamocortical activity. Biol Chem 2023; 404:303-310. [PMID: 36453998 DOI: 10.1515/hsz-2022-0215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 11/12/2022] [Indexed: 12/03/2022]
Abstract
It is known that the thalamus plays an important role in pathological brain conditions involved in demyelinating, inflammatory and neurodegenerative diseases such as Multiple Sclerosis (MS). Beside immune cells and cytokines, ion channels were found to be key players in neuroinflammation. MS is a prototypical example of an autoimmune disease of the central nervous system that is classified as a channelopathy where abnormal ion channel function leads to symptoms and clinical signs. Here we review the influence of the cytokine-ion channel interaction in the thalamocortical system in demyelination and inflammation.
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Affiliation(s)
- Nicole Rychlik
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany
| | - Petra Hundehege
- Department of Neurology with Institute of Translational Neurology, D-48149 Münster, Germany
| | - Thomas Budde
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany
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Mittli D, Tukacs V, Ravasz L, Csősz É, Kozma T, Kardos J, Juhász G, Kékesi KA. LPS-induced acute neuroinflammation, involving interleukin-1 beta signaling, leads to proteomic, cellular, and network-level changes in the prefrontal cortex of mice. Brain Behav Immun Health 2023; 28:100594. [PMID: 36713475 PMCID: PMC9880243 DOI: 10.1016/j.bbih.2023.100594] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/12/2022] [Accepted: 01/16/2023] [Indexed: 01/22/2023] Open
Abstract
Neuroinflammation induced by peripheral infections leads to various neuropsychiatric symptoms both in humans and laboratory animals, e.g., to the manifestation of sickness behavior that resembles some features of clinical depression. However, in addition to depression-like behavior, there are other symptoms of acute systemic inflammation that can be associated with the impairment of prefrontal cortex (PFC)-regulated cognitive functions. Thus, we investigated the electrophysiological and proteomic alterations of the PFC using brain slices and the lipopolysaccharide (LPS) model of acute peripheral infection in male mice. Based on the gene expression differences of the coreceptor (Il1rap) of interleukin-1 beta (IL-1β) between neuron types in our previous single-cell sequencing dataset, we first compared the electrophysiological effects of IL-1β on PFC pyramidal cells and interneurons. We found that pyramidal cells are more responsive to IL-1β, as could be presumed from our transcriptomic data. To examine the possible circuit-level correlates of the cellular changes, frontal electroencephalographic (EEG) activity and fronto-occipital functional connectivity were analyzed in LPS-treated mice and significant changes were found in the fronto-occipital EEG correlation and coherence in the delta and high-gamma frequency bands. The upregulation of the prefrontal IL-1 system (IL-1β and its receptor) after LPS treatment was revealed by immunoassays simultaneously with the observed EEG changes. Furthermore, we investigated the LPS-induced alterations of the synaptic proteome in the PFC using 2-D differential gel electrophoresis and mass spectrometry and found 48 altered proteins mainly related to cellular signaling, cytoskeletal organization, and carbohydrate/energy metabolism. Thus, our results indicate remarkable electrophysiological and molecular changes in the PFC related to acute systemic inflammation that may explain some of the concomitant behavioral and physiological symptoms.
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Affiliation(s)
- Dániel Mittli
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Department of Physiology and Neurobiology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Vanda Tukacs
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Lilla Ravasz
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- CRU Hungary Ltd., Göd, Hungary
| | - Éva Csősz
- Proteomics Core Facility, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | | | - József Kardos
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Gábor Juhász
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- CRU Hungary Ltd., Göd, Hungary
- InnoScience Ltd., Mátranovák, Hungary
| | - Katalin Adrienna Kékesi
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Department of Physiology and Neurobiology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- InnoScience Ltd., Mátranovák, Hungary
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Cholesterol-induced robust Ca oscillation in astrocytes required for survival and lipid droplet formation in high-cholesterol condition. iScience 2022; 25:105138. [PMID: 36185358 PMCID: PMC9523397 DOI: 10.1016/j.isci.2022.105138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 08/08/2022] [Accepted: 09/10/2022] [Indexed: 11/22/2022] Open
Abstract
Cholesterol, one of the major cell membrane components, stabilizes membrane fluidity and regulates signal transduction. Beside its canonical roles, cholesterol has been reported to directly activate signaling pathways such as hedgehog (Hh). We recently found that astrocytes, one of the glial cells, respond to Hh pathway stimulation by Ca signaling. These notions led us to test if extracellularly applied cholesterol triggers Ca signaling in astrocytes. Here, we found that cholesterol application induces robust Ca oscillation only in astrocytes with different properties from the Hh-induced Ca response. The Ca oscillation has a long delay which corresponds to the onset of cholesterol accumulation in the plasma membrane. Blockade of the Ca oscillation resulted in enhancement of astrocytic cell death and disturbance of lipid droplet formation, implying a possibility that the cholesterol-induced Ca oscillation plays important roles in astrocytic survival and cholesterol handling under pathological conditions of cholesterol load such as demyelination. Robust Ca oscillation by cholesterol in astrocytes but not in neurons and microglia Cholesterol-induced Ca oscillation relates to membrane cholesterol accumulation The Ca oscillation is driven via the PLC-IP3 signaling pathway Ca oscillation inhibition leads to astrocytic death and lipid droplet malformation
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Oniani T, Vinnenberg L, Chaudhary R, Schreiber JA, Riske K, Williams B, Pape HC, White JA, Junker A, Seebohm G, Meuth SG, Hundehege P, Budde T, Zobeiri M. Effects of Axonal Demyelination, Inflammatory Cytokines and Divalent Cation Chelators on Thalamic HCN Channels and Oscillatory Bursting. Int J Mol Sci 2022; 23:ijms23116285. [PMID: 35682964 PMCID: PMC9181513 DOI: 10.3390/ijms23116285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/31/2022] [Accepted: 05/31/2022] [Indexed: 12/13/2022] Open
Abstract
Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that is characterized by the progressive loss of oligodendrocytes and myelin and is associated with thalamic dysfunction. Cuprizone (CPZ)-induced general demyelination in rodents is a valuable model for studying different aspects of MS pathology. CPZ feeding is associated with the altered distribution and expression of different ion channels along neuronal somata and axons. However, it is largely unknown whether the copper chelator CPZ directly influences ion channels. Therefore, we assessed the effects of different divalent cations (copper; zinc) and trace metal chelators (EDTA; Tricine; the water-soluble derivative of CPZ, BiMPi) on hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that are major mediators of thalamic function and pathology. In addition, alterations of HCN channels induced by CPZ treatment and MS-related proinflammatory cytokines (IL-1β; IL-6; INF-α; INF-β) were characterized in C57Bl/6J mice. Thus, the hyperpolarization-activated inward current (Ih) was recorded in thalamocortical (TC) neurons and heterologous expression systems (mHCN2 expressing HEK cells; hHCN4 expressing oocytes). A number of electrophysiological characteristics of Ih (potential of half-maximal activation (V0.5); current density; activation kinetics) were unchanged following the extracellular application of trace metals and divalent cation chelators to native neurons, cell cultures or oocytes. Mice were fed a diet containing 0.2% CPZ for 35 days, resulting in general demyelination in the brain. Withdrawal of CPZ from the diet resulted in rapid remyelination, the effects of which were assessed at three time points after stopping CPZ feeding (Day1, Day7, Day25). In TC neurons, Ih was decreased on Day1 and Day25 and revealed a transient increased availability on Day7. In addition, we challenged naive TC neurons with INF-α and IL-1β. It was found that Ih parameters were differentially altered by the application of the two cytokines to thalamic cells, while IL-1β increased the availability of HCN channels (depolarized V0.5; increased current density) and the excitability of TC neurons (depolarized resting membrane potential (RMP); increased the number of action potentials (APs); produced a larger voltage sag; promoted higher input resistance; increased the number of burst spikes; hyperpolarized the AP threshold), INF-α mediated contrary effects. The effect of cytokine modulation on thalamic bursting was further assessed in horizontal slices and a computational model of slow thalamic oscillations. Here, IL-1β and INF-α increased and reduced oscillatory bursting, respectively. We conclude that HCN channels are not directly modulated by trace metals and divalent cation chelators but are subject to modulation by different MS-related cytokines.
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Affiliation(s)
- Tengiz Oniani
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany; (T.O.); (R.C.); (H.-C.P.); (M.Z.)
| | - Laura Vinnenberg
- Department of Neurology with Institute of Translational Neurology, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany; (L.V.); (P.H.)
| | - Rahul Chaudhary
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany; (T.O.); (R.C.); (H.-C.P.); (M.Z.)
| | - Julian A. Schreiber
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, Corren-Str. 48, D-48149 Münster, Germany;
- Cellular Electrophysiology and Molecular Biology, Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Robert-Koch-Str. 45, D-48149 Münster, Germany;
| | - Kathrin Riske
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität, Waldeyer-Str. 15, D-48149 Münster, Germany; (K.R.); (A.J.)
| | - Brandon Williams
- Center for Systems Neuroscience, Neurophotonics Center, Department of Biomedical Engineering, Boston University, 610 Commonwealth Ave., Boston, MA 02215, USA; (B.W.); (J.A.W.)
| | - Hans-Christian Pape
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany; (T.O.); (R.C.); (H.-C.P.); (M.Z.)
| | - John A. White
- Center for Systems Neuroscience, Neurophotonics Center, Department of Biomedical Engineering, Boston University, 610 Commonwealth Ave., Boston, MA 02215, USA; (B.W.); (J.A.W.)
| | - Anna Junker
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität, Waldeyer-Str. 15, D-48149 Münster, Germany; (K.R.); (A.J.)
| | - Guiscard Seebohm
- Cellular Electrophysiology and Molecular Biology, Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Robert-Koch-Str. 45, D-48149 Münster, Germany;
| | - Sven G. Meuth
- Neurology Clinic, University Clinic Düsseldorf, Moorenstraße 5, D-40225 Düsseldorf, Germany;
| | - Petra Hundehege
- Department of Neurology with Institute of Translational Neurology, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany; (L.V.); (P.H.)
| | - Thomas Budde
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany; (T.O.); (R.C.); (H.-C.P.); (M.Z.)
- Correspondence:
| | - Mehrnoush Zobeiri
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149 Münster, Germany; (T.O.); (R.C.); (H.-C.P.); (M.Z.)
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Chaudhary R, Albrecht S, Datunashvili M, Cerina M, Lüttjohann A, Han Y, Narayanan V, Chetkovich DM, Ruck T, Kuhlmann T, Pape HC, Meuth SG, Zobeiri M, Budde T. Modulation of Pacemaker Channel Function in a Model of Thalamocortical Hyperexcitability by Demyelination and Cytokines. Cereb Cortex 2022; 32:4397-4421. [PMID: 35076711 PMCID: PMC9574242 DOI: 10.1093/cercor/bhab491] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/26/2021] [Accepted: 11/28/2021] [Indexed: 12/02/2022] Open
Abstract
A consensus is yet to be reached regarding the exact prevalence of epileptic seizures or epilepsy in multiple sclerosis (MS). In addition, the underlying pathophysiological basis of the reciprocal interaction among neuroinflammation, demyelination, and epilepsy remains unclear. Therefore, a better understanding of cellular and network mechanisms linking these pathologies is needed. Cuprizone-induced general demyelination in rodents is a valuable model for studying MS pathologies. Here, we studied the relationship among epileptic activity, loss of myelin, and pro-inflammatory cytokines by inducing acute, generalized demyelination in a genetic mouse model of human absence epilepsy, C3H/HeJ mice. Both cellular and network mechanisms were studied using in vivo and in vitro electrophysiological techniques. We found that acute, generalized demyelination in C3H/HeJ mice resulted in a lower number of spike–wave discharges, increased cortical theta oscillations, and reduction of slow rhythmic intrathalamic burst activity. In addition, generalized demyelination resulted in a significant reduction in the amplitude of the hyperpolarization-activated inward current (Ih) in thalamic relay cells, which was accompanied by lower surface expression of hyperpolarization-activated, cyclic nucleotide-gated channels, and the phosphorylated form of TRIP8b (pS237-TRIP8b). We suggest that demyelination-related changes in thalamic Ih may be one of the factors defining the prevalence of seizures in MS.
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Affiliation(s)
- Rahul Chaudhary
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Stefanie Albrecht
- Institute of Neuropathology, University Hospital Münster, 48149 Münster, Germany
| | - Maia Datunashvili
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Manuela Cerina
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Annika Lüttjohann
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Ye Han
- Vanderbilt University Medical Center, Department of Neurology, Nashville, TN 37232, USA
| | - Venu Narayanan
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Dane M Chetkovich
- Vanderbilt University Medical Center, Department of Neurology, Nashville, TN 37232, USA
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Tanja Kuhlmann
- Institute of Neuropathology, University Hospital Münster, 48149 Münster, Germany
| | - Hans-Christian Pape
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149 Münster, Germany
| | - Sven G Meuth
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-Universität, 48149 Münster, Germany
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Mehrnoush Zobeiri
- Address correspondence to Dr Thomas Budde, Wilhelms-Universität, Institut für Physiologie I, Robert-Koch-Str. 27a, D-48149 Münster, Germany. ; Dr Mehrnoush Zobeiri, Wilhelms-Universität, Institut für Physiologie I, Robert-Koch-Str. 27a, D-48149 Münster, Germany.
| | - Thomas Budde
- Address correspondence to Dr Thomas Budde, Wilhelms-Universität, Institut für Physiologie I, Robert-Koch-Str. 27a, D-48149 Münster, Germany. ; Dr Mehrnoush Zobeiri, Wilhelms-Universität, Institut für Physiologie I, Robert-Koch-Str. 27a, D-48149 Münster, Germany.
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Features of Action Potentials from Identified Thalamic Nuclei in Anesthetized Patients. Brain Sci 2020; 10:brainsci10121002. [PMID: 33348660 PMCID: PMC7766545 DOI: 10.3390/brainsci10121002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/24/2020] [Accepted: 12/14/2020] [Indexed: 11/23/2022] Open
Abstract
Our objective was to describe the electrophysiological properties of the extracellular action potential (AP) picked up through microelectrode recordings (MERs). Five patients were operated under general anesthesia for centromedian deep brain stimulation (DBS). APs from the same cell were pooled to obtain a mean AP (mAP). The amplitudes and durations for all 2/3 phases were computed from the mAP, together with the maximum (dVmax) and minimum (dVmin) values of the first derivative, as well as the slopes of different phases during repolarization. The mAPs are denominated according to the phase polarity (P/N for positive/negative). We obtained a total of 1109 mAPs, most of the positive (98.47%) and triphasic (93.69%) with a small P/N deflection (Vphase1) before depolarization. The percentage of the different types of mAPs was different for the nuclei addressed. The relationship between dVmax and the depolarizing phase is specific. The descending phase of the first derivative identified different phases during the repolarizing period. We observed a high correlation between Vphase1 and the amplitudes of either depolarization or repolarization phases. Human thalamic nuclei differ in their electrophysiological properties of APs, even under general anesthesia. Capacitive current, which is probably responsible for Vphase1, is very common in thalamic APs. Moreover, subtle differences during repolarization are neuron-specific.
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Adachi C, Kakinuma N, Jo SH, Ishii T, Arai Y, Arai S, Kitaguchi T, Takeda S, Inoue T. Sonic hedgehog enhances calcium oscillations in hippocampal astrocytes. J Biol Chem 2019; 294:16034-16048. [PMID: 31506300 DOI: 10.1074/jbc.ra119.007883] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 09/04/2019] [Indexed: 01/05/2023] Open
Abstract
Sonic hedgehog (SHH) is important for organogenesis during development. Recent studies have indicated that SHH is also involved in the proliferation and transformation of astrocytes to the reactive phenotype. However, the mechanisms underlying these are unknown. Involvement of SHH signaling in calcium (Ca) signaling has not been extensively studied. Here, we report that SHH and Smoothened agonist (SAG), an activator of the signaling receptor Smoothened (SMO) in the SHH pathway, activate Ca oscillations in cultured murine hippocampal astrocytes. The response was rapid, on a minute time scale, indicating a noncanonical pathway activity. Pertussis toxin blocked the SAG effect, indicating an involvement of a Gi coupled to SMO. Depletion of extracellular ATP by apyrase, an ATP-degrading enzyme, inhibited the SAG-mediated activation of Ca oscillations. These results indicate that SAG increases extracellular ATP levels by activating ATP release from astrocytes, resulting in Ca oscillation activation. We hypothesize that SHH activates SMO-coupled Gi in astrocytes, causing ATP release and activation of Gq/11-coupled P2 receptors on the same cell or surrounding astrocytes. Transcription factor activities are often modulated by Ca patterns; therefore, SHH signaling may trigger changes in astrocytes by activating Ca oscillations. This enhancement of Ca oscillations by SHH signaling may occur in astrocytes in the brain in vivo because we also observed it in hippocampal brain slices. In summary, SHH and SAG enhance Ca oscillations in hippocampal astrocytes, Gi mediates SAG-induced Ca oscillations downstream of SMO, and ATP-permeable channels may promote the ATP release that activates Ca oscillations in astrocytes.
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Affiliation(s)
- Chihiro Adachi
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 1628480, Japan
| | - Naoto Kakinuma
- Department of Anatomy and Cell Biology, Interdisciplinary School of Medicine & Engineering, University of Yamanashi, Yamanashi 4093898, Japan
| | - Soo Hyun Jo
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 1628480, Japan
| | - Takayuki Ishii
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 1628480, Japan
| | - Yusuke Arai
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 1628480, Japan
| | - Satoshi Arai
- Cell Signaling Group, Waseda Bioscience Research Institute in Singapore (WABIOS), Singapore 138667.,Research Institute for Science and Engineering, Waseda University, Tokyo 1698555, Japan
| | - Tetsuya Kitaguchi
- Cell Signaling Group, Waseda Bioscience Research Institute in Singapore (WABIOS), Singapore 138667.,Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 2268503, Japan
| | - Sen Takeda
- Department of Anatomy and Cell Biology, Interdisciplinary School of Medicine & Engineering, University of Yamanashi, Yamanashi 4093898, Japan
| | - Takafumi Inoue
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 1628480, Japan
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Gruol DL, Huitron-Resendiz S, Roberts AJ. Altered brain activity during withdrawal from chronic alcohol is associated with changes in IL-6 signal transduction and GABAergic mechanisms in transgenic mice with increased astrocyte expression of IL-6. Neuropharmacology 2018; 138:32-46. [PMID: 29787738 DOI: 10.1016/j.neuropharm.2018.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/25/2018] [Accepted: 05/17/2018] [Indexed: 10/16/2022]
Abstract
Interleukin-6 (IL-6) is an important neuroimmune factor that is increased in the brain by alcohol exposure/withdrawal and is thought to play a role in the actions of alcohol on the brain. To gain insight into IL-6/alcohol/withdrawal interactions and how these interactions affect the brain, we are studying the effects of chronic binge alcohol exposure on transgenic mice that express elevated levels of IL-6 in the brain due to increased astrocyte expression (IL-6 tg) and their non-transgenic (non-tg) littermate controls. IL-6/alcohol/withdrawal interactions were identified by genotypic differences in spontaneous brain activity in electroencephalogram (EEG) recordings from the mice, and by Western blot analysis of protein activation or expression in hippocampus obtained from the mice after the final alcohol withdrawal period. Results from EEG studies showed frequency dependent genotypic differences in brain activity during withdrawal. For EEG frequencies that were affected by alcohol exposure/withdrawal in both genotypes, the nature of the effect was similar, but differed across withdrawal cycles. Differences between IL-6 tg and non-tg mice were also observed in Western blot studies of the activated form of STAT3 (phosphoSTAT3), a signal transduction partner of IL-6, and subunits of GABAA receptors (GABAAR). Regression analysis revealed that pSTAT3 played a more prominent role during withdrawal in the IL-6 tg mice than in the non-tg mice, and that the role of GABAAR alpha-5 and GABAAR alpha-1 in brain activity varied across genotype and withdrawal. Taken together, our results suggest that IL-6 can significantly impact mechanisms involved in alcohol withdrawal.
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Affiliation(s)
- Donna L Gruol
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | | | - Amanda J Roberts
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA, 92037, USA
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Walsh DA, Brown JT, Randall AD. In vitro characterization of cell-level neurophysiological diversity in the rostral nucleus reuniens of adult mice. J Physiol 2017; 595:3549-3572. [PMID: 28295330 PMCID: PMC5451734 DOI: 10.1113/jp273915] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS The nucleus reuniens (Re), a nucleus of the midline thalamus, is part of a cognitive network including the hippocampus and the medial prefrontal cortex. To date, very few studies have examined the electrophysiological properties of Re neurons at a cellular level. The majority of Re neurons exhibit spontaneous action potential firing at rest. This is independent of classical amino-acid mediated synaptic transmission. When driven by various forms of depolarizing current stimulus, Re neurons display considerable diversity in their firing patterns. As a result of the presence of a low threshold Ca2+ channel, spike output functions are strongly modulated by the prestimulus membrane potential. Finally, we describe a novel form of activity-dependant intrinsic plasticity that eliminates the high-frequency burst firing present in many Re neurons. These results provide a comprehensive summary of the intrinsic electrophysiological properties of Re neurons allowing us to better consider the role of the Re in cognitive processes. ABSTRACT The nucleus reuniens (Re) is the largest of the midline thalamic nuclei. We have performed a detailed neurophysiological characterization of neurons in the rostral Re of brain slices prepared from adult male mice. At resting potential (-63.7 ± 0.6 mV), ∼90% of Re neurons fired action potentials, typically continuously at ∼8 Hz. Although Re neurons experience a significant spontaneous barrage of fast, amino-acid-mediate synaptic transmission, this was not predominantly responsible for spontaneous spiking because firing persisted in the presence of glutamate and GABA receptor antagonists. With resting potential preset to -80 mV, -20 pA current injections revealed a mean input resistance of 615 MΩ and a mean time constant of 38 ms. Following cessation of this stimulus, a significant rebound potential was seen that was sometimes sufficiently large to trigger a short burst of very high frequency (100-300 Hz) firing. In most cells, short (2 ms), strong (2 nA) current injections elicited a single spike followed by a large afterdepolarizing potential which, when suprathreshold, generated high-frequency spiking. Similarly, in the majority of cells preset at -80 mV, 500 ms depolarizing current injections to cells led to a brief initial burst of very high-frequency firing, although this was lost when cells were preset at -72 mV. Biophysical and pharmacological experiments indicate a prominent role for T-type Ca2+ channels in the high-frequency bursting of Re neurons. Finally, we describe a novel form of activity-dependent intrinsic plasticity that persistently eliminates the burst firing potential of Re neurons.
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Affiliation(s)
- Darren A. Walsh
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
| | - Jonathan T. Brown
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
| | - Andrew D. Randall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
- School of Clinical SciencesUniversity of BristolBristolUK
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