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Nissenkorn A, Bar L, Ben-Bassat A, Rothstein L, Abdelrahim H, Sokol R, Gabis LV, Attali B. Donepezil as a new therapeutic potential in KCNQ2- and KCNQ3-related autism. Front Cell Neurosci 2024; 18:1380442. [PMID: 39175503 PMCID: PMC11338814 DOI: 10.3389/fncel.2024.1380442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 07/29/2024] [Indexed: 08/24/2024] Open
Abstract
Introduction The KCNQ2/KCNQ3 genes encode the voltage-gated K channel underlying the neuronal M-current, regulating neuronal excitability. Loss-of-function (LoF) variants cause neonatal epilepsy, treatable with the M-current-opener retigabine, which is no longer marketed due to side effects. Gain-of-function (GoF) variants cause developmental encephalopathy and autism that could be amenable to M-current, but such therapies are not clinically available. In this translational project, we investigated whether donepezil, a cholinergic drug used in Alzheimer's, suppresses M currents in vitro and improves cognitive symptoms in patients with GoF variants. Methods (1) The effect of 1 μM donepezil on the amplitude of the M-current was measured in excitatory and inhibitory neurons of mouse primary cultured hippocampal cells. M-current was measured using the standard deactivation protocol (holding at 0 mV and deactivation at -60 mV) in the voltage-clamp configuration of the whole-cell patch clamp technique. The impact of donepezil was also examined on the spontaneous firing activity of hippocampal neurons in the current-clamp configuration. (2) Four children with autism, aged 2.5-8 years, with the following GoF variants were enrolled: KCNQ2 (p. Arg144Gln) and KCNQ 3 (p.Arg227Gln, p.Arg230Cys). Patients were treated off-label with donepezil 2.5-5 mg/d for 12 months and assessed with: clinical Global Impression of Change (CGI-c), Childhood Autism Rating Scale 2 (CARS-2), Adaptive Behavior Assessment System-II (ABAS-II), and Child Development Inventory (CDI). Results (1) Application of donepezil for at least 6 min produced a significant inhibition of the M-current with an IC50 of 0.4 μM. At 1 μM, donepezil reduced by 67% the M-current density of excitatory neurons (2.4 ± 0.46 vs. 0.89 ± 0.15 pA/pF, p < 0.05*). In inhibitory neurons, application of 1 μM donepezil produced a lesser inhibition of 59% of the M-current density (1.39 ± 0.43 vs. 0.57 ± 0.21, p > 0.05). Donepezil (1 μM) potently increased by 2.6-fold the spontaneous firing frequency, which was prevented by the muscarinic receptor antagonist atropine (10 μM). (2) The CARS-2 decreased by 3.8 ± 4.9 points (p > 0.05), but in two patients with KCNQ3 variants, the improvement was over the 4.5 clinically relevant threshold. The global clinical change was also clinically significant in these patients (CGI-c = 1). The CDI increased by 65% (p < 0.05*), while the ABAS-II remained unchanged. Discussion Donepezil should be repurposed as a novel alternative treatment for GoF variants in KCNQ2/KCNQ3 encephalopathy.
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Affiliation(s)
- Andreea Nissenkorn
- Pediatric Neurology Unit, Edith Wolfson Medical Center, Holon, Israel
- Magen National Center for Rare Disorders, Edith Wolfson Medical Center, Holon, Israel
- Department of Pediatric, School of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Lior Bar
- Department of Electrophysiology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ariel Ben-Bassat
- Department of Electrophysiology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lynn Rothstein
- Pediatric Neurology Unit, Edith Wolfson Medical Center, Holon, Israel
- Magen National Center for Rare Disorders, Edith Wolfson Medical Center, Holon, Israel
| | - Hoda Abdelrahim
- Pediatric Neurology Unit, Edith Wolfson Medical Center, Holon, Israel
- Magen National Center for Rare Disorders, Edith Wolfson Medical Center, Holon, Israel
| | - Riki Sokol
- Pediatric Neurology Unit, Edith Wolfson Medical Center, Holon, Israel
| | - Lidia V. Gabis
- Magen National Center for Rare Disorders, Edith Wolfson Medical Center, Holon, Israel
- Department of Pediatric, School of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Bernard Attali
- Department of Electrophysiology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Qiu J, Voliotis M, Bosch MA, Li XF, Zweifel LS, Tsaneva-Atanasova K, O’Byrne KT, Rønnekleiv OK, Kelly MJ. Estradiol elicits distinct firing patterns in arcuate nucleus kisspeptin neurons of females through altering ion channel conductances. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.20.581121. [PMID: 38915596 PMCID: PMC11195100 DOI: 10.1101/2024.02.20.581121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Hypothalamic kisspeptin (Kiss1) neurons are vital for pubertal development and reproduction. Arcuate nucleus Kiss1 (Kiss1ARH) neurons are responsible for the pulsatile release of Gonadotropin-releasing Hormone (GnRH). In females, the behavior of Kiss1ARH neurons, expressing Kiss1, Neurokinin B (NKB), and Dynorphin (Dyn), varies throughout the ovarian cycle. Studies indicate that 17β-estradiol (E2) reduces peptide expression but increases Vglut2 mRNA and glutamate neurotransmission in these neurons, suggesting a shift from peptidergic to glutamatergic signaling. To investigate this shift, we combined transcriptomics, electrophysiology, and mathematical modeling. Our results demonstrate that E2 treatment upregulates the mRNA expression of voltage-activated calcium channels, elevating the whole-cell calcium current and that contribute to high-frequency burst firing. Additionally, E2 treatment decreased the mRNA levels of Canonical Transient Receptor Potential (TPRC) 5 and G protein-coupled K+ (GIRK) channels. When TRPC5 channels in Kiss1ARH neurons were deleted using CRISPR, the slow excitatory postsynaptic potential (sEPSP) was eliminated. Our data enabled us to formulate a biophysically realistic mathematical model of the Kiss1ARH neuron, suggesting that E2 modifies ionic conductances in Kiss1ARH neurons, enabling the transition from high frequency synchronous firing through NKB-driven activation of TRPC5 channels to a short bursting mode facilitating glutamate release. In a low E2 milieu, synchronous firing of Kiss1ARH neurons drives pulsatile release of GnRH, while the transition to burst firing with high, preovulatory levels of E2 would facilitate the GnRH surge through its glutamatergic synaptic connection to preoptic Kiss1 neurons.
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Affiliation(s)
- Jian Qiu
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Margaritis Voliotis
- Department of Mathematics and Statistics, University of Exeter, Stocker Rd, Exeter, EX4 4PY, UK
- Living Systems Institute, University of Exeter, Stocker Rd, Exeter, EX4 4PY, UK
| | - Martha A. Bosch
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Xiao Feng Li
- Department of Women and Children’s Health, School of Life Course and Population Sciences, King’s College London, Guy’s Campus, London SE1 1UL, UK
| | - Larry S. Zweifel
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
- Depatment of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Krasimira Tsaneva-Atanasova
- Department of Mathematics and Statistics, University of Exeter, Stocker Rd, Exeter, EX4 4PY, UK
- Living Systems Institute, University of Exeter, Stocker Rd, Exeter, EX4 4PY, UK
| | - Kevin T. O’Byrne
- Department of Women and Children’s Health, School of Life Course and Population Sciences, King’s College London, Guy’s Campus, London SE1 1UL, UK
| | - Oline K. Rønnekleiv
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA
| | - Martin J. Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA
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3
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Kandel MB, Zhuang GZ, Goins WF, Marzulli M, Zhang M, Glorioso JC, Kang Y, Levitt AE, Kwok WM, Levitt RC, Sarantopoulos KD. rdHSV-CA8 non-opioid analgesic gene therapy decreases somatosensory neuronal excitability by activating Kv7 voltage-gated potassium channels. Front Mol Neurosci 2024; 17:1398839. [PMID: 38783904 PMCID: PMC11112096 DOI: 10.3389/fnmol.2024.1398839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 04/18/2024] [Indexed: 05/25/2024] Open
Abstract
Chronic pain is common and inadequately treated, making the development of safe and effective analgesics a high priority. Our previous data indicate that carbonic anhydrase-8 (CA8) expression in dorsal root ganglia (DRG) mediates analgesia via inhibition of neuronal ER inositol trisphosphate receptor-1 (ITPR1) via subsequent decrease in ER calcium release and reduction of cytoplasmic free calcium, essential to the regulation of neuronal excitability. This study tested the hypothesis that novel JDNI8 replication-defective herpes simplex-1 viral vectors (rdHSV) carrying a CA8 transgene (vHCA8) reduce primary afferent neuronal excitability. Whole-cell current clamp recordings in small DRG neurons showed that vHCA8 transduction caused prolongation of their afterhyperpolarization (AHP), an essential regulator of neuronal excitability. This AHP prolongation was completely reversed by the specific Kv7 channel inhibitor XE-991. Voltage clamp recordings indicate an effect via Kv7 channels in vHCA8-infected small DRG neurons. These data demonstrate for the first time that vHCA8 produces Kv7 channel activation, which decreases neuronal excitability in nociceptors. This suppression of excitability may translate in vivo as non-opioid dependent behavioral- or clinical analgesia, if proven behaviorally and clinically.
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Affiliation(s)
- Munal B. Kandel
- Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Gerald Z. Zhuang
- Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, FL, United States
| | - William F. Goins
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Marco Marzulli
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Mingdi Zhang
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Joseph C. Glorioso
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Yuan Kang
- Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Alexandra E. Levitt
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Wai-Meng Kwok
- Department of Anesthesiology and Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Roy C. Levitt
- Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, FL, United States
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
- John T. MacDonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, United States
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Konstantinos D. Sarantopoulos
- Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, FL, United States
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
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Xia M, Anderson TL, Prantzalos ER, Hawkinson TR, Clarke HA, Keohane SB, Sun RC, Turner JR, Ortinski PI. Voltage-gated potassium channels control extended access cocaine seeking: a role for nucleus accumbens astrocytes. Neuropsychopharmacology 2024; 49:551-560. [PMID: 37660129 PMCID: PMC10789875 DOI: 10.1038/s41386-023-01718-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 08/03/2023] [Accepted: 08/21/2023] [Indexed: 09/04/2023]
Abstract
Dopaminergic signaling in the nucleus accumbens shell (NAc) regulates neuronal activity relevant to reward-related learning, including cocaine-associated behaviors. Although astrocytes respond to dopamine and cocaine with structural changes, the impact of dopamine and cocaine on astrocyte functional plasticity has not been widely studied. Specifically, behavioral implications of voltage-gated channel activity in the canonically non-excitable astrocytes are not known. We characterized potassium channel function in NAc astrocytes following exposure to exogenous dopamine or cocaine self-administration training under short (2 h/day) and extended (6 h/day) access schedules. Electrophysiological, Ca2+ imaging, mRNA, and mass spectrometry tools were used for molecular characterization. Behavioral effects were examined after NAc-targeted microinjections of channel antagonists and astroglial toxins. Exogenous dopamine increased activity of currents mediated by voltage-gated (Kv7) channels in NAc astrocytes. This was associated with a ~5-fold increase in expression of Kcnq2 transcript level in homogenized NAc micropunches. Matrix-assisted laser desorption/ionization mass spectrometry revealed increased NAc dopamine levels in extended access, relative to short access, rats. Kv7 inhibition selectively increased frequency and amplitude of astrocyte intracellular Ca2+ transients in NAc of extended access rats. Inhibition of Kv7 channels in the NAc attenuated cocaine-seeking in extended access rats only, an effect that was occluded by microinjection of the astrocyte metabolic poison, fluorocitrate. These results suggest that voltage-gated K+ channel signaling in NAc astrocytes is behaviorally relevant, support Kv7-mediated regulation of astrocyte Ca2+ signals, and propose novel mechanisms of neuroglial interactions relevant to drug use.
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Affiliation(s)
- Mengfan Xia
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Tanner L Anderson
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
| | - Emily R Prantzalos
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Tara R Hawkinson
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Harrison A Clarke
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Shannon B Keohane
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Ramon C Sun
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, FL, USA
| | - Jill R Turner
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Pavel I Ortinski
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA.
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Alhassen L, Alhassen W, Wong C, Sun Y, Xia Z, Civelli O, Hoshi N. Dehydroepiandrosterone Sulfate (DHEAS) Is an Endogenous Kv7 Channel Modulator That Reduces Kv7/M-Current Suppression and Inflammatory Pain. J Neurosci 2023; 43:7073-7083. [PMID: 37648450 PMCID: PMC10601364 DOI: 10.1523/jneurosci.2307-22.2023] [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: 12/18/2022] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 09/01/2023] Open
Abstract
Neuronal Kv7 voltage-gated potassium channels generate the M-current and regulate neuronal excitability. Here, we report that dehydroepiandrosterone sulfate (DHEAS) is an endogenous Kv7 channel modulator that attenuates Gq-coupled receptor-induced M-current suppression. DHEAS reduced muscarinic agonist-induced Kv7-current suppression of Kv7.1, Kv7.2, Kv7.4, or Kv7.5 homomeric currents and endogenous M-currents in rat sympathetic ganglion neurons. However, DHEAS per se did not alter the voltage dependence of these Kv7 homomeric channels or the m1 receptor-induced activation of phospholipase C or protein kinase C. DHEAS-treated Kv7.2 homomeric currents became resistant to depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) induced by voltage-activated phosphatase, Ci-VSP or eVSP. Our computational models predicted a novel binding site for DHEAS in the cytoplasmic domain of Kv7 subunits. A single-point mutation of the predicted key histidine into cysteine in the rat Kv7.2 subunit, rKv7.2(H558C), resulted in a loss of effects of DHEAS on muscarinic Kv7 current suppression. Furthermore, in vivo administration of DHEAS in mice of both sexes reduced late phase pain responses in the formalin paw test. However, it did not have effects on early phase responses in the formalin paw test or responses in the hot plate test. Coadministration of a selective Kv7 inhibitor, XE991, and DHEAS eliminated analgesic effects of DHEAS in late phase responses in the formalin paw test. Collectively, these results suggest that DHEAS attenuates M-current suppression by stabilizing PIP2-Kv7 subunit interaction and can mitigate inflammatory pain.SIGNIFICANCE STATEMENT M-current suppression induced by stimulation of Gq-coupled receptors is a form of Kv7 current modulation that can reversibly increase neuronal excitability. This study demonstrates that DHEAS, an endogenous steroid hormone, is a novel Kv7 channel modulator that can attenuate M-current suppression without affecting basal Kv7 channel kinetics. Administration of DHEAS in vivo alleviated inflammatory pain in rodents. These results suggest that the degree of M-current suppression can be dynamically regulated by small molecules. Therefore, this novel form of Kv7 channel regulation holds promising potential as a therapeutic target for sensitized nervous activities, such as inflammatory pain.
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Affiliation(s)
- Lamees Alhassen
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Wedad Alhassen
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Cindy Wong
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Yuxuan Sun
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Zelin Xia
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Olivier Civelli
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
| | - Naoto Hoshi
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92697
- Department of Physiology and Biophysics, University of California-Irvine, Irvine, California 92697
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6
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Kanyo R, Lamothe SM, Urrutia A, Goodchild SJ, Allison WT, Dean R, Kurata HT. Site and Mechanism of ML252 Inhibition of Kv7 Voltage-Gated Potassium Channels. FUNCTION 2023; 4:zqad021. [PMID: 37342413 PMCID: PMC10278987 DOI: 10.1093/function/zqad021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 06/22/2023] Open
Abstract
Kv7 (KCNQ) voltage-gated potassium channels are critical regulators of neuronal excitability and are candidate targets for development of antiseizure medications. Drug discovery efforts have identified small molecules that modulate channel function and reveal mechanistic insights into Kv7 channel physiological roles. While Kv7 channel activators have therapeutic benefits, inhibitors are useful for understanding channel function and mechanistic validation of candidate drugs. In this study, we reveal the mechanism of a Kv7.2/Kv7.3 inhibitor, ML252. We used docking and electrophysiology to identify critical residues involved in ML252 sensitivity. Most notably, Kv7.2[W236F] or Kv7.3[W265F] mutations strongly attenuate ML252 sensitivity. This tryptophan residue in the pore is also required for sensitivity to certain activators, including retigabine and ML213. We used automated planar patch clamp electrophysiology to assess competitive interactions between ML252 and different Kv7 activator subtypes. A pore-targeted activator (ML213) weakens the inhibitory effects of ML252, whereas a distinct activator subtype (ICA-069673) that targets the voltage sensor does not prevent ML252 inhibition. Using transgenic zebrafish larvae expressing an optical reporter (CaMPARI) to measure neural activity in-vivo, we demonstrate that Kv7 inhibition by ML252 increases neuronal excitability. Consistent with in-vitro data, ML213 suppresses ML252 induced neuronal activity, while the voltage-sensor targeted activator ICA-069673 does not prevent ML252 actions. In summary, this study establishes a binding site and mechanism of action of ML252, classifying this poorly understood drug as a pore-targeted Kv7 channel inhibitor that binds to the same tryptophan residue as commonly used pore-targeted Kv7 activators. ML213 and ML252 likely have overlapping sites of interaction in the pore Kv7.2 and Kv7.3 channels, resulting in competitive interactions. In contrast, the VSD-targeted activator ICA-069673 does not prevent channel inhibition by ML252.
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Affiliation(s)
- Richard Kanyo
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, 9-70 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Shawn M Lamothe
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, 9-70 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Arturo Urrutia
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
| | - Samuel J Goodchild
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
| | - W Ted Allison
- Dept. of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Richard Dean
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
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Potassium channelopathies associated with epilepsy-related syndromes and directions for therapeutic intervention. Biochem Pharmacol 2023; 208:115413. [PMID: 36646291 DOI: 10.1016/j.bcp.2023.115413] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
A number of mutations to members of several CNS potassium (K) channel families have been identified which result in rare forms of neonatal onset epilepsy, or syndromes of which one prominent characteristic is a form of epilepsy. Benign Familial Neonatal Convulsions or Seizures (BFNC or BFNS), also referred to as Self-Limited Familial Neonatal Epilepsy (SeLNE), results from mutations in 2 members of the KV7 family (KCNQ) of K channels; while generally self-resolving by about 15 weeks of age, these mutations significantly increase the probability of generalized seizure disorders in the adult, in some cases they result in more severe developmental syndromes. Epilepsy of Infancy with Migrating Focal Seizures (EIMSF), or Migrating Partial Seizures of Infancy (MMPSI), is a rare severe form of epilepsy linked primarily to gain of function mutations in a member of the sodium-dependent K channel family, KCNT1 or SLACK. Finally, KCNMA1 channelopathies, including Liang-Wang syndrome (LIWAS), are rare combinations of neurological symptoms including seizure, movement abnormalities, delayed development and intellectual disabilities, with Liang-Wang syndrome an extremely serious polymalformative syndrome with a number of neurological sequelae including epilepsy. These are caused by mutations in the pore-forming subunit of the large-conductance calcium-activated K channel (BK channel) KCNMA1. The identification of these rare but significant channelopathies has resulted in a resurgence of interest in their treatment by direct pharmacological or genetic modulation. We will briefly review the genetics, biophysics and pharmacology of these K channels, their linkage with the 3 syndromes described above, and efforts to more effectively target these syndromes.
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Stampf JL, Ciotu CI, Heber S, Boehm S, Fischer MJM, Salzer I. Analgesic Action of Acetaminophen via Kv7 Channels. Int J Mol Sci 2022; 24:ijms24010650. [PMID: 36614094 PMCID: PMC9820628 DOI: 10.3390/ijms24010650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 01/03/2023] Open
Abstract
The mechanism of acetaminophen (APAP) analgesia is at least partially unknown. Previously, we showed that the APAP metabolite N-acetyl-p-benzoquinone imine (NAPQI) activated Kv7 channels in neurons in vitro, and this activation of Kv7 channels dampened neuronal firing. Here, the effect of the Kv7 channel blocker XE991 on APAP-induced analgesia was investigated in vivo. APAP had no effect on naive animals. Induction of inflammation with λ-carrageenan lowered mechanical and thermal thresholds. Systemic treatment with APAP reduced mechanical hyperalgesia, and co-application of XE991 reduced APAP's analgesic effect on mechanical pain. In a second experiment, the analgesic effect of systemic APAP was not antagonized by intrathecal XE991 application. Analysis of liver samples revealed APAP and glutathione-coupled APAP indicative of metabolization. However, there were no relevant levels of these metabolites in cerebrospinal fluid, suggesting no relevant APAP metabolite formation in the CNS. In summary, the results support an analgesic action of APAP by activating Kv7 channels at a peripheral site through formation of the metabolite NAPQI.
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Ying Y, Gong L, Tao X, Ding J, Chen N, Yao Y, Liu J, Chen C, Zhu T, Jiang P. Genetic Knockout of TRPM2 Increases Neuronal Excitability of Hippocampal Neurons by Inhibiting Kv7 Channel in Epilepsy. Mol Neurobiol 2022; 59:6918-6933. [PMID: 36053438 DOI: 10.1007/s12035-022-02993-2] [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: 04/26/2022] [Accepted: 08/07/2022] [Indexed: 11/30/2022]
Abstract
Epilepsy is a chronic brain disease that makes serious cognitive and motor retardation. Ion channels affect the occurrence of epilepsy in various ways, but the mechanisms have not yet been fully elucidated. Transient receptor potential melastain2 (TRPM2) ion channel is a non-selective cationic channel that can permeate Ca2+ and critical for epilepsy. Here, TRPM2 gene knockout mice were used to generate a chronic kindling epilepsy model by PTZ administration in mice. We found that TRPM2 knockout mice were more susceptible to epilepsy than WT mice. Furthermore, the neuronal excitability in the hippocampal CA1 region of TRPM2 knockout mice was significantly increased. Compared with WT group, there were no significant differences in the input resistance and after hyperpolarization of CA1 neurons in TRPM2 knockout mice. Firing adaptation rate of hippocampal CA1 pyramidal neurons of TRPM2 knockout mice was lower than that of WT mice. We also found that activation of Kv7 channel by retigabine reduced the firing frequency of action potential in the hippocampal pyramidal neurons of TRPM2 knockout mice. However, inhibiting Kv7 channel increased the firing frequency of action potential in hippocampal pyramidal neurons of WT mice. The data suggest that activation of Kv7 channel can effectively reduce epileptic seizures in TRPM2 knockout mice. We conclude that genetic knockout of TRPM2 in hippocampal CA1 pyramidal neurons may increase neuronal excitability by inhibiting Kv7 channel, affecting the susceptibility to epilepsy. These findings may provide a potential therapeutic target for epilepsy.
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Affiliation(s)
- Yingchao Ying
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Lifen Gong
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiaohan Tao
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Junchao Ding
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- Department of Pediatrics, Yiwu Maternal and Child Health Care Hospital, Yiwu, China
| | - Nannan Chen
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yinping Yao
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- Department of Pediatrics, Shaoxing People's Hospital, Shaoxing, China
| | - Jiajing Liu
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Chen Chen
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Tao Zhu
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Peifang Jiang
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
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10
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Jing J, Dunbar C, Sonesra A, Chavez A, Park S, Yang R, Soh H, Lee M, Tzingounis AV, Cooper EC, Jiang X, Maheshwari A. Removal of KCNQ2 from parvalbumin-expressing interneurons improves anti-seizure efficacy of retigabine. Exp Neurol 2022; 355:114141. [PMID: 35691372 PMCID: PMC9899633 DOI: 10.1016/j.expneurol.2022.114141] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/18/2022] [Accepted: 06/06/2022] [Indexed: 02/07/2023]
Abstract
Anti-seizure drug (ASD) targets are widely expressed in both excitatory and inhibitory neurons. It remains unknown if the action of an ASD upon inhibitory neurons could counteract its beneficial effects on excitatory neurons (or vice versa), thereby reducing the efficacy of the ASD. Here, we examine whether the efficacy of the ASD retigabine (RTG) is altered after removal of the Kv7 potassium channel subunit KCNQ2, one of its drug targets, from parvalbumin-expressing interneurons (PV-INs). Parvalbumin-Cre (PV-Cre) mice were crossed with Kcnq2-floxed (Kcnq2fl/fl) mice to conditionally delete Kcnq2 from PV-INs. In these conditional knockout mice (cKO, PV-Kcnq2fl/fl), RTG (10 mg/kg, i.p.) significantly delayed the onset of either picrotoxin (PTX, 10 mg/kg, i.p)- or kainic acid (KA, 30 mg/kg, i.p.)-induced convulsive seizures compared to vehicle, while RTG was not effective in wild-type littermates (WT). Immunostaining for KCNQ2 and KCNQ3 revealed that both subunits were enriched at axon initial segments (AISs) of hippocampal CA1 PV-INs, and their specific expression was selectively abolished in cKO mice. Accordingly, the M-currents recorded from CA1 PV-INs and their sensitivity to RTG were significantly reduced in cKO mice. While the ability of RTG to suppress CA1 excitatory neurons in hippocampal slices was unchanged in cKO mice, its suppressive effect on the spike activity of CA1 PV-INs was significantly reduced compared with WT mice. In addition, the RTG-induced suppression on intrinsic membrane excitability of PV-INs in WT mice was significantly reduced in cKO mice. These findings suggest that preventing RTG from suppressing PV-INs improves its anticonvulsant effect.
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Affiliation(s)
- Junzhan Jing
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States of America
| | - Corrinne Dunbar
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Alina Sonesra
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Ana Chavez
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Suhyeorn Park
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Ryan Yang
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Heun Soh
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd, Storrs, CT 06269, United States of America
| | - Maxwell Lee
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd, Storrs, CT 06269, United States of America
| | - Edward C Cooper
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America; Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America; Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America
| | - Xiaolong Jiang
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States of America.
| | - Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America; Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States of America.
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11
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Joshi P, Patel R, Kang SY, Serbinowski E, Lee MY. Establishment of ion channel and ABC transporter assays in 3D-cultured ReNcell VM on a 384-pillar plate for neurotoxicity potential. Toxicol In Vitro 2022; 82:105375. [PMID: 35550413 DOI: 10.1016/j.tiv.2022.105375] [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: 09/17/2021] [Revised: 04/05/2022] [Accepted: 05/03/2022] [Indexed: 10/18/2022]
Abstract
Neurotoxicity potential of compounds by inhibition of ion channels and efflux transporters has been studied traditionally using two-dimensionally (2D) cultured cell lines such as CHO and HEK-293 overexpressing the protein of interest. However, these approaches are time consuming and do not recapitulate the activity of ion channels and efflux transporters indigenously expressed in neural stem cells (NSCs) in vivo. To overcome these issues, we established ion channel and transporter assays on a 384-pillar plate with three-dimensionally (3D) cultured ReNcell VM and demonstrated high-throughput measurement of ion channel and transporter activity. RNA sequencing analysis identified major ion channels and efflux transporters expressed in ReNcell VM, followed by validating 3D ReNcell-based ion channel and transporter assays with model compounds. Major ion channel activities were measured by specifically inhibiting potassium channels Kv 7.2 with XE-991 and Kv 4.3 with fluoxetine, and a calcium channel with 2-APB. Activities of major efflux transporters, MDR1, MRP1, and BCRP, were assessed using their respective blockers, verapamil, probenecid, and novobiocin. From this study, we demonstrated that 3D-cultured ReNcell VM on the 384-pillar plate could be a good alternative to rapidly identify environmental chemicals and therapeutic compounds for their role in modulating the activity of ion channels and efflux transporters, potentially leading to neurotoxicity.
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Affiliation(s)
- Pranav Joshi
- Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; Bioprinting Laboratories Inc, Denton, TX, USA
| | - Rushabh Patel
- Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Soo-Yeon Kang
- Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; Department of Biomedical Engineering, University of North Texas, Denton, TX, USA
| | - Emily Serbinowski
- Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Moo-Yeal Lee
- Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; Department of Biomedical Engineering, University of North Texas, Denton, TX, USA.
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12
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The KCNQ channel inhibitor XE991 suppresses nicotinic acetylcholine receptor-mediated responses in rat intracardiac ganglion neurons. Pharmacol Rep 2022; 74:745-751. [PMID: 35672575 DOI: 10.1007/s43440-022-00375-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/29/2022] [Accepted: 05/13/2022] [Indexed: 10/18/2022]
Abstract
BACKGROUND XE991 (10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone) is reportedly a potent and selective Kv7 (KCNQ) channel inhibitor. This study aimed to evaluate how XE991 affects nicotinic responses in intracardiac ganglion neurons. METHODS We studied how the KCNQ channel inhibitor XE991 could affect nicotinic responses in acutely isolated rat intracardiac ganglion neurons using a perforated patch-clamp recording configuration and Ca2+ imaging. RESULTS XE991 reversibly and concentration-dependently inhibited the nicotine (10 μM)-induced current with an IC50 of 14.4 μM. The EC50 values for nicotine-induced currents in the absence and presence of 10 μM XE991 were 8.7 and 12.0 μM, respectively. Because XE991 suppressed the maximum response of the nicotine concentration-response curve, the inhibitory effect of this drug appears to be noncompetitive. In addition, linopirdine reduced the amplitude of 10 µM nicotine-induced currents with an IC50 value of 16.9 μM. The inorganic KCNQ channel inhibitor Ba2+ affected neither the nicotine-induced current nor the inhibitory effect of XE991 on the nicotinic response. The KCNQ activator flupirtine at a concentration of 10 μM slightly but markedly inhibited the nicotine-induced current. Finally, XE991 inhibited the nicotine-induced elevation of intracellular calcium concentration and the nicotine-induced firing of action potentials. CONCLUSION We propose that XE991 inhibits nicotinic acetylcholine receptors in intracardiac ganglion neurons, which in turn attenuate nicotine-induced neuronal excitation.
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Ketamine exerts its sustained antidepressant effects via cell-type-specific regulation of Kcnq2. Neuron 2022; 110:2283-2298.e9. [PMID: 35649415 DOI: 10.1016/j.neuron.2022.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 03/01/2022] [Accepted: 05/02/2022] [Indexed: 12/20/2022]
Abstract
A single sub-anesthetic dose of ketamine produces a rapid and sustained antidepressant response, yet the molecular mechanisms responsible for this remain unclear. Here, we identified cell-type-specific transcriptional signatures associated with a sustained ketamine response in mice. Most interestingly, we identified the Kcnq2 gene as an important downstream regulator of ketamine action in glutamatergic neurons of the ventral hippocampus. We validated these findings through a series of complementary molecular, electrophysiological, cellular, pharmacological, behavioral, and functional experiments. We demonstrated that adjunctive treatment with retigabine, a KCNQ activator, augments ketamine's antidepressant-like effects in mice. Intriguingly, these effects are ketamine specific, as they do not modulate a response to classical antidepressants, such as escitalopram. These findings significantly advance our understanding of the mechanisms underlying the sustained antidepressant effects of ketamine, with important clinical implications.
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14
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Biba N, Becq H, Pallesi-Pocachard E, Sarno S, Granjeaud S, Montheil A, Kurz M, Villard L, Milh M, Santini PPL, Aniksztejn L. Time-limited alterations in cortical activity of a knock-in mice model of KCNQ2-related developmental and epileptic encephalopathy. J Physiol 2022; 600:2429-2460. [PMID: 35389519 DOI: 10.1113/jp282536] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The electrophysiological impact of the pathogenic c.821C>T mutation of the KCNQ2 gene (p.T274M variant in Kv7.2 subunit) related to Developmental and Epileptic Encephalopathy has been analyzed both in vivo and ex-vivo in layers II/III and V of motor cortical slice from a knock-in mice model during development at neonatal, post-weaning and juvenile stages. M current density and conductance are decreased and excitability of layers II/III pyramidal cells is increased in slices from neonatal and post-weaning KI mice but not from juvenile KI mice. M current and excitability of layer V pyramidal cells are impacted in KI mice only at post-weaning stage. Spontaneous GABAergic network-driven events are recorded until post-weaning stage and their frequency are increased in layers II/III of the KI mice. KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. ABSTRACT De novo missense variants in the KCNQ2 gene encoding the Kv7.2 subunit of the voltage-gated potassium Kv7/M channels are the main cause of Developmental and Epileptic Encephalopathy (DEE) with neonatal onset. While seizures usually resolve during development, cognitive/motor deficits persist. To better understand the cellular mechanisms underlying network dysfunction and their progression over time, we investigated in vivo, using local field potential recordings of freely moving animals, and ex-vivo in layers II/III and V of motor cortical slices, using patch-clamp recordings, the electrophysiological properties of pyramidal cells from a heterozygous knock-in (KI) mouse model carrying the Kv7.2 p.T274M pathogenic variant during neonatal, post-weaning and juvenile developmental stages. We found that KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. At the cellular level, the variant led to a reduction in M current density/conductance and to neuronal hyperexcitability. These alterations were observed during the neonatal period in pyramidal cells of layers II /III and during post-weaning stage in pyramidal cells of layer V. Moreover, there was an increase in the frequency of spontaneous network driven events mediated by GABA receptors suggesting that the excitability of interneurons was also increased. However, all these alterations were no more observed in layers II/III and V of juvenile mice. Thus, our data indicate that the action of the variant is developmentally regulated. This raises the possibility that the age related seizure remission observed in KCNQ2-related DEE patient results from a time limited alteration of Kv7 channels activity and neuronal excitability. Abstract figure legend Knock-in mice harboring the heterozygous pathogenic p.T274M variant in the Kv7.2 subunit (c.821C>T mutation of the KCNQ2 gene) related to Developmental and Epileptic Encephalopathy displayed epileptic seizures preferentially at post-weaning rather than at juvenile developmental stages. At cellular level, in motor cortical slices the variant led to a reduction in M current density, to a hyperexcitability of pyramidal cells and to an increase in the frequency of spontaneous network driven events mediated by GABA receptors. All these alterations are time limited and are observed in pyramidal cells of neonatal mice until post-weaning but not of juvenile mice in which the pyramidal cells have electrophysiological properties similar to those of wild-type mice. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Najoua Biba
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Hélène Becq
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Emilie Pallesi-Pocachard
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Stefania Sarno
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Samuel Granjeaud
- Centre de Recherche en Cancérologie de Marseille, INSERM, U1068, Institut Paoli Calmettes, CNRS, UMR7258, Aix-Marseille University UM 105, Marseille, France
| | - Aurélie Montheil
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Marie Kurz
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Laurent Villard
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Medical Genetics, La Timone Childrens's Hospital, Marseille, France
| | - Mathieu Milh
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Pediatric Neurology, La Timone Children's Hospital, Marseille, France
| | | | - Laurent Aniksztejn
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
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15
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Ye H, Liu ZX, He YJ, Wang X. Effects of M currents on the persistent activity of pyramidal neurons in mouse primary auditory cortex. J Neurophysiol 2022; 127:1269-1278. [PMID: 35294269 DOI: 10.1152/jn.00332.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuronal persistent activity (PA) is a common phenomenon observed in many types of neurons. PA can be induced in neurons in the mouse auditory nucleus by activating cholinergic receptors with carbachol (CCh), a dual muscarinic and nicotinic receptor agonist. PA is presumed to be associated with learning-related auditory plasticity at the cellular level. However, the mechanism is not clearly understood. Many studies have reported that muscarinic cholinergic receptor agonists inhibit muscarinic-sensitive potassium channels (M channels). Potassium influx through M channels produces potassium currents, called M currents, which play an essential role in regulating neural excitability and synaptic plasticity. Further study is needed to determine whether M currents affect the PA of auditory central neurons and provide additional analysis of the variations in electrophysiological properties. We used in vitro whole-cell patch-clamp recordings in isolated mouse brain slices to investigate the effects of M currents on the PA in pyramidal neurons in layer V of the primary auditory cortex (AI-L5). We found that blocking M currents with XE991 depolarized the AI-L5 pyramidal neurons, which significantly increased the input resistance. The active threshold and threshold intensity were significantly reduced, indicating that the intrinsic excitability was enhanced. Our results also showed that blocking M currents with XE991 switched the neuronal firing patterns in the AI-L5 pyramidal neurons from regular-spiking to intrinsic-bursting. Blocking M currents facilitated PA by increasing the plateau potential and enhancing intrinsic excitability. Our results suggested that blocking M currents might facilitate the PA in AI-L5 pyramidal neurons, which underlies auditory plasticity.
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Affiliation(s)
- Huan Ye
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Zhen-Xu Liu
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Ya-Jie He
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Xin Wang
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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16
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Hasan A, Hasan R. Empagliflozin Relaxes Resistance Mesenteric Arteries by Stimulating Multiple Smooth Muscle Cell Voltage-Gated K + (K V) Channels. Int J Mol Sci 2021; 22:10842. [PMID: 34639181 PMCID: PMC8509755 DOI: 10.3390/ijms221910842] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/26/2021] [Accepted: 10/04/2021] [Indexed: 12/31/2022] Open
Abstract
The antidiabetic drug empagliflozin is reported to produce a range of cardiovascular effects, including a reduction in systemic blood pressure. However, whether empagliflozin directly modulates the contractility of resistance-size mesenteric arteries remains unclear. Here, we sought to investigate if empagliflozin could relax resistance-size rat mesenteric arteries and the associated underlying molecular mechanisms. We found that acute empagliflozin application produces a concentration-dependent vasodilation in myogenic, depolarized and phenylephrine (PE)-preconstricted mesenteric arteries. Selective inhibition of smooth muscle cell voltage-gated K+ channels KV1.5 and KV7 abolished empagliflozin-induced vasodilation. In contrast, pharmacological inhibition of large-conductance Ca2+-activated K+ (BKCa) channels and ATP-sensitive (KATP) channels did not abolish vasodilation. Inhibition of the vasodilatory signaling axis involving endothelial nitric oxide (NO), smooth muscle cell soluble guanylyl cyclase (sGC) and protein kinase G (PKG) did not abolish empagliflozin-evoked vasodilation. Inhibition of the endothelium-derived vasodilatory molecule prostacyclin (PGI2) had no effect on the vasodilation. Consistently, empagliflozin-evoked vasodilation remained unaltered by endothelium denudation. Overall, our data suggest that empagliflozin stimulates smooth muscle cell KV channels KV1.5 and KV7, resulting in vasodilation in resistance-size mesenteric arteries. This study demonstrates for the first time a novel mechanism whereby empagliflozin regulates arterial contractility, resulting in vasodilation. Due to known antihypertensive properties, treatment with empagliflozin may complement conventional antihypertensive therapy.
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Affiliation(s)
| | - Raquibul Hasan
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, GA 30341, USA;
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17
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Robert V, Therreau L, Davatolhagh MF, Bernardo-Garcia FJ, Clements KN, Chevaleyre V, Piskorowski RA. The mechanisms shaping CA2 pyramidal neuron action potential bursting induced by muscarinic acetylcholine receptor activation. J Gen Physiol 2021; 152:133812. [PMID: 32069351 PMCID: PMC7141590 DOI: 10.1085/jgp.201912462] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/18/2019] [Accepted: 01/13/2020] [Indexed: 01/04/2023] Open
Abstract
Recent studies have revealed that hippocampal area CA2 plays an important role in hippocampal network function. Disruption of this region has been implicated in neuropsychiatric disorders. It is well appreciated that cholinergic input to the hippocampus plays an important role in learning and memory. While the effect of elevated cholinergic tone has been well studied in areas CA1 and CA3, it remains unclear how changes in cholinergic tone impact synaptic transmission and the intrinsic properties of neurons in area CA2. In this study, we applied the cholinergic agonist carbachol and performed on-cell, whole-cell, and extracellular recordings in area CA2. We observed that under conditions of high cholinergic tone, CA2 pyramidal neurons depolarized and rhythmically fired bursts of action potentials. This depolarization depended on the activation of M1 and M3 cholinergic receptors. Furthermore, we examined how the intrinsic properties and action-potential firing were altered in CA2 pyramidal neurons treated with 10 µM carbachol. While this intrinsic burst firing persisted in the absence of synaptic transmission, bursts were shaped by synaptic inputs in the intact network. We found that both excitatory and inhibitory synaptic transmission were reduced upon carbachol treatment. Finally, we examined the contribution of different channels to the cholinergic-induced changes in neuronal properties. We found that a conductance from Kv7 channels partially contributed to carbachol-induced changes in resting membrane potential and membrane resistance. We also found that D-type potassium currents contributed to controlling several properties of the bursts, including firing rate and burst kinetics. Furthermore, we determined that T-type calcium channels and small conductance calcium-activated potassium channels play a role in regulating bursting activity.
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Affiliation(s)
- Vincent Robert
- Université Paris Descartes, Inserm UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Paris, France
| | - Ludivine Therreau
- Université Paris Descartes, Inserm UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Paris, France
| | - M Felicia Davatolhagh
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - F Javier Bernardo-Garcia
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA
| | | | - Vivien Chevaleyre
- Université Paris Descartes, Inserm UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Paris, France
| | - Rebecca A Piskorowski
- Université Paris Descartes, Inserm UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Paris, France
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18
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Wright AB, Sukhanova KY, Elmslie KS. K V7 channels are potential regulators of the exercise pressor reflex. J Neurophysiol 2021; 126:1-10. [PMID: 34038189 DOI: 10.1152/jn.00700.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The exercise pressor reflex (EPR) originates in skeletal muscle and is activated by exercise-induced signals to increase arterial blood pressure and cardiac output. Muscle ischemia can elicit the EPR, which can be inappropriately activated in patients with peripheral vascular disease or heart failure to increase the incidence of myocardial infarction. We seek to better understand the receptor/channels that control excitability of group III and group IV muscle afferent fibers that give rise to the EPR. Bradykinin (BK) is released within contracting muscle and can evoke the EPR. However, the mechanism is incompletely understood. KV7 channels strongly regulate neuronal excitability and are inhibited by BK. We have identified KV7 currents in muscle afferent neurons by their characteristic activation/deactivation kinetics, enhancement by the KV7 activator retigabine, and block by KV7 specific inhibitor XE991. The blocking of KV7 current by different XE991 concentrations suggests that the KV7 current is generated by both KV7.2/7.3 (high affinity) and KV7.5 (low affinity) channels. The KV7 current was inhibited by 300 nM BK in neurons with diameters consistent with both group III and group IV afferents. The inhibition of KV7 by BK could be a mechanism by which this metabolic mediator generates the EPR. Furthermore, our results suggest that KV7 channel activators such as retigabine, could be used to reduce cardiac stress resulting from the exacerbated EPR in patients with cardiovascular disease.NEW & NOTEWORTHY KV7 channels control neuronal excitability. We show that these channels are expressed in muscle afferents and generate currents that are blocked by XE991 and bradykinin (BK). The XE991 block suggests that KV7 current is generated by KV7.2/3 and KV7.5 channels. The BK inhibition of KV7 channels may explain how BK activates the exercise pressor reflex (EPR). Retigabine can enhance KV7 current, which could help control the inappropriately activated EPR in patients with cardiovascular disease.
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Affiliation(s)
- Andrew B Wright
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Khrystyna Yu Sukhanova
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
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Revill AL, Katzell A, Del Negro CA, Milsom WK, Funk GD. KCNQ Current Contributes to Inspiratory Burst Termination in the Pre-Bötzinger Complex of Neonatal Rats in vitro. Front Physiol 2021; 12:626470. [PMID: 33927636 PMCID: PMC8078421 DOI: 10.3389/fphys.2021.626470] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/23/2021] [Indexed: 12/23/2022] Open
Abstract
The pre-Bötzinger complex (preBötC) of the ventral medulla generates the mammalian inspiratory breathing rhythm. When isolated in explants and deprived of synaptic inhibition, the preBötC continues to generate inspiratory-related rhythm. Mechanisms underlying burst generation have been investigated for decades, but cellular and synaptic mechanisms responsible for burst termination have received less attention. KCNQ-mediated K+ currents contribute to burst termination in other systems, and their transcripts are expressed in preBötC neurons. Therefore, we tested the hypothesis that KCNQ channels also contribute to burst termination in the preBötC. We recorded KCNQ-like currents in preBötC inspiratory neurons in neonatal rat slices that retain respiratory rhythmicity. Blocking KCNQ channels with XE991 or linopirdine (applied via superfusion or locally) increased inspiratory burst duration by 2- to 3-fold. By contrast, activation of KCNQ with retigabine decreased inspiratory burst duration by ~35%. These data from reduced preparations suggest that the KCNQ current in preBötC neurons contributes to inspiratory burst termination.
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Affiliation(s)
- Ann L. Revill
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Alexis Katzell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | | | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Gregory D. Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
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Changes in Excitability Properties of Ventromedial Motor Thalamic Neurons in 6-OHDA Lesioned Mice. eNeuro 2021; 8:ENEURO.0436-20.2021. [PMID: 33509950 PMCID: PMC7920540 DOI: 10.1523/eneuro.0436-20.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 01/19/2021] [Accepted: 01/24/2021] [Indexed: 12/12/2022] Open
Abstract
The activity of basal ganglia input receiving motor thalamus (BGMT) makes a critical impact on motor cortical processing, but modification in BGMT processing with Parkinsonian conditions has not be investigated at the cellular level. Such changes may well be expected because of homeostatic regulation of neural excitability in the presence of altered synaptic drive with dopamine depletion. We addressed this question by comparing BGMT properties in brain slice recordings between control and unilaterally 6-hydroxydopamine hydrochloride (6-OHDA)-treated adult mice. At a minimum of one month after 6-OHDA treatment, BGMT neurons showed a highly significant increase in intrinsic excitability, which was primarily because of a decrease in M-type potassium current. BGMT neurons after 6-OHDA treatment also showed an increase in T-type calcium rebound spikes following hyperpolarizing current steps. Biophysical computer modeling of a thalamic neuron demonstrated that an increase in rebound spiking can also be accounted for by a decrease in the M-type potassium current. Modeling also showed that an increase in sag with hyperpolarizing steps found after 6-OHDA treatment could in part but not fully be accounted for by the decrease in M-type current. These findings support the hypothesis that homeostatic changes in BGMT neural properties following 6-OHDA treatment likely influence the signal processing taking place in the BG thalamocortical network in Parkinson’s disease.
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21
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Deardorff AS, Romer SH, Fyffe RE. Location, location, location: the organization and roles of potassium channels in mammalian motoneurons. J Physiol 2021; 599:1391-1420. [DOI: 10.1113/jp278675] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Adam S. Deardorff
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
- Department of Neurology and Internal Medicine, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
| | - Shannon H. Romer
- Odyssey Systems Environmental Health Effects Laboratory, Navy Medical Research Unit‐Dayton Wright‐Patterson Air Force Base OH 45433 USA
| | - Robert E.W. Fyffe
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
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22
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Li T, Wu K, Yue Z, Wang Y, Zhang F, Shen H. Structural Basis for the Modulation of Human KCNQ4 by Small-Molecule Drugs. Mol Cell 2020; 81:25-37.e4. [PMID: 33238160 DOI: 10.1016/j.molcel.2020.10.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/28/2020] [Accepted: 10/28/2020] [Indexed: 12/17/2022]
Abstract
Among the five KCNQ channels, also known as the Kv7 voltage-gated potassium (Kv) channels, KCNQ2-KCNQ5 control neuronal excitability. Dysfunctions of KCNQ2-KCNQ5 are associated with neurological disorders such as epilepsy, deafness, and neuropathic pain. Here, we report the cryoelectron microscopy (cryo-EM) structures of human KCNQ4 and its complexes with the opener retigabine or the blocker linopirdine at overall resolutions of 2.5, 3.1, and 3.3 Å, respectively. In all structures, a phosphatidylinositol 4,5-bisphosphate (PIP2) molecule inserts its head group into a cavity within each voltage-sensing domain (VSD), revealing an unobserved binding mode for PIP2. Retigabine nestles in each fenestration, inducing local shifts. Instead of staying within the central pore, linopirdine resides in a cytosolic cavity underneath the inner gate. Electrophysiological analyses of various mutants corroborated the structural observations. Our studies reveal the molecular basis for the modulatory mechanism of neuronal KCNQ channels and provide a framework for structure-facilitated drug discovery targeting these important channels.
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Affiliation(s)
- Tian Li
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Kun Wu
- Emergency Medicine Clinical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Zhenlei Yue
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Yifei Wang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Fan Zhang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Huaizong Shen
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China.
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23
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Hydrogen Sulfide Relaxes Human Uterine Artery via Activating Smooth Muscle BK Ca Channels. Antioxidants (Basel) 2020; 9:antiox9111127. [PMID: 33202933 PMCID: PMC7697977 DOI: 10.3390/antiox9111127] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/29/2020] [Accepted: 11/06/2020] [Indexed: 12/16/2022] Open
Abstract
Opening of large conductance calcium-activated and voltage-dependent potassium (BKCa) channels hyperpolarizes plasma membranes of smooth muscle (SM) to cause vasodilation, underling a key mechanism for mediating uterine artery (UA) dilation in pregnancy. Hydrogen sulfide (H2S) has been recently identified as a new UA vasodilator, yet the mechanism underlying H2S-induced UA dilation is unknown. Here, we tested whether H2S activated BKCa channels in human UA smooth muscle cells (hUASMC) to mediate UA relaxation. Multiple BKCa subunits were found in human UA in vitro and hUASMC in vitro, and high β1 and γ1 proteins were localized in SM cells in human UA. Baseline outward currents, recorded by whole-cell and single-channel patch clamps, were significantly inhibited by specific BKCa blockers iberiotoxin (IBTX) or tetraethylammonium, showing specific BKCa activity in hUASMC. H2S dose (NaHS, 1–1000 µM)-dependently potentiated BKCa currents and open probability. Co-incubation with a Ca2+ blocker nifedipine (5 µM) or a chelator (ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), 5 mM) did not alter H2S-potentiated BKCa currents and open probability. NaHS also dose-dependently relaxed phenylephrine pre-constricted freshly prepared human UA rings, which was inhibited by IBTX. Thus, H2S stimulated human UA relaxation at least partially via activating SM BKCa channels independent of extracellular Ca2+.
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24
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The M-current works in tandem with the persistent sodium current to set the speed of locomotion. PLoS Biol 2020; 18:e3000738. [PMID: 33186352 PMCID: PMC7688130 DOI: 10.1371/journal.pbio.3000738] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 11/25/2020] [Accepted: 10/13/2020] [Indexed: 01/20/2023] Open
Abstract
The central pattern generator (CPG) for locomotion is a set of pacemaker neurons endowed with inherent bursting driven by the persistent sodium current (INaP). How they proceed to regulate the locomotor rhythm remained unknown. Here, in neonatal rodents, we identified a persistent potassium current critical in regulating pacemakers and locomotion speed. This current recapitulates features of the M-current (IM): a subthreshold noninactivating outward current blocked by 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) and enhanced by N-(2-chloro-5-pyrimidinyl)-3,4-difluorobenzamide (ICA73). Immunostaining and mutant mice highlight an important role of Kv7.2-containing channels in mediating IM. Pharmacological modulation of IM regulates the emergence and the frequency regime of both pacemaker and CPG activities and controls the speed of locomotion. Computational models captured these results and showed how an interplay between IM and INaP endows the locomotor CPG with rhythmogenic properties. Overall, this study provides fundamental insights into how IM and INaP work in tandem to set the speed of locomotion.
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In Vivo Attenuation of M-Current Suppression Impairs Consolidation of Object Recognition Memory. J Neurosci 2020; 40:5847-5856. [PMID: 32554550 DOI: 10.1523/jneurosci.0348-20.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/08/2020] [Accepted: 06/06/2020] [Indexed: 11/21/2022] Open
Abstract
The M-current is a low voltage-activated potassium current generated by neuronal Kv7 channels. A prominent role of the M-current is to a create transient increase of neuronal excitability in response to neurotransmitters through the suppression of this current. Accordingly, M-current suppression is assumed to be involved in higher brain functions including learning and memory. However, there is little evidence supporting such a role to date. To address this gap, we examined behavioral tasks to assess learning and memory in homozygous Kv7.2 knock-in mice, Kv7.2(S559A), which show reduced M-current suppression while maintaining a normal basal M-current activity in neurons. We found that Kv7.2(S559A) mice had normal object location memory and contextual fear memory, but impaired long-term object recognition memory. Furthermore, short-term memory for object recognition was intact in Kv7.2(S559A) mice. The deficit in long-term object recognition memory was restored by the administration of a selective Kv7 channel inhibitor, XE991, when delivered during the memory consolidation phase. Lastly, c-Fos induction 2 h after training in Kv7.2(S559A) mice was normal in the hippocampus, which corresponds to intact object location memory, but was reduced in the perirhinal cortex, which corresponds to impaired long-term object recognition memory. Together, these results support the overall conclusion that M-current suppression is important for memory consolidation of specific types of memories.SIGNIFICANCE STATEMENT Dynamic regulation of neuronal excitation is a fundamental mechanism for information processing in the brain, which is mediated by changes in synaptic transmissions or by changes in ion channel activity. Some neurotransmitters can facilitate action potential firing by suppression of a low voltage-activated potassium current, M-current. We demonstrate that M-current suppression is critical for establishment of long-term object recognition memory, but is not required for establishment of hippocampus-dependent location memory or contextual memory. This study suggests that M-current suppression is important for stable encoding of specific types of memories.
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26
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Valdor M, Wagner A, Fischer H, Röhrs V, Schröder W, Bahrenberg G, Welbers A, Fechner H, Kurreck J, Tzschentke TM, Christoph T. RNA interference-mediated silencing of Kv7.2 in rat dorsal root ganglion neurons abolishes the anti-nociceptive effect of a selective channel opener. J Pharmacol Toxicol Methods 2020; 103:106693. [DOI: 10.1016/j.vascn.2020.106693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/25/2020] [Accepted: 03/20/2020] [Indexed: 02/07/2023]
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27
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Vay SU, Flitsch LJ, Rabenstein M, Monière H, Jakovcevski I, Andjus P, Bijelic D, Blaschke S, Walter HL, Fink GR, Schroeter M, Rueger MA. The impact of hyperpolarization-activated cyclic nucleotide-gated (HCN) and voltage-gated potassium KCNQ/Kv7 channels on primary microglia function. J Neuroinflammation 2020; 17:100. [PMID: 32248813 PMCID: PMC7132998 DOI: 10.1186/s12974-020-01779-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/18/2020] [Indexed: 01/03/2023] Open
Abstract
Background Microglia are essential to maintain cell homeostasis in the healthy brain and are activated after brain injury. Upon activation, microglia polarize towards different phenotypes. The course of microglia activation is complex and depends on signals in the surrounding milieu. Recently, it has been suggested that microglia respond to ion currents, as a way of regulating their activity and function. Methods and results Under the hypothesis that HCN and KCNQ/Kv7 channels impact on microglia, we studied primary rat microglia in the presence or absence of specific pharmacological blockade or RNA silencing. Primary microglia expressed the subunits HCN1-4, Kv7.2, Kv7.3, and Kv7.5. The expression of HCN2, as well as Kv7.2 and Kv7.3, varied among different microglia phenotypes. The pharmacological blockade of HCN channels by ZD7288 resulted in cell depolarization with slowly rising intracellular calcium levels, leading to enhanced survival and reduced proliferation rates of resting microglia. Furthermore, ZD7288 treatment, as well as knockdown of HCN2 RNA by small interfering RNA, resulted in an attenuation of later microglia activation—both towards the anti- and pro-inflammatory phenotype. However, HCN channel inhibition enhanced the phagocytic capacity of IL4-stimulated microglia. Blockade of Kv7/KCNQ channel by XE-991 exclusively inhibited the migratory capacity of resting microglia. Conclusion These observations suggest that the HCN current contributes to various microglia functions and impacts on the course of microglia activation, while the Kv7/KCNQ channels affect microglia migration. Characterizing the role of HCN channels in microglial functioning may offer new therapeutic approaches for targeted modulation of neuroinflammation as a hallmark of various neurological disorders.
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Affiliation(s)
- Sabine Ulrike Vay
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany.
| | - Lea Jessica Flitsch
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany
| | - Monika Rabenstein
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany
| | - Helena Monière
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany
| | - Igor Jakovcevski
- Institute for Molecular and Behavioural Neuroscience and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Pavle Andjus
- Center for Laser Microscopy-CLM, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Dunja Bijelic
- Center for Laser Microscopy-CLM, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Stefan Blaschke
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
| | - Helene Luise Walter
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany
| | - Gereon Rudolf Fink
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
| | - Michael Schroeter
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
| | - Maria Adele Rueger
- Department of Neurology, Faculty of Medicine and University Hospital, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
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28
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Tzingounis AV. SMITten for KCNQ Channels. Biophys J 2019; 113:503-505. [PMID: 28793205 DOI: 10.1016/j.bpj.2017.06.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 06/25/2017] [Accepted: 06/30/2017] [Indexed: 11/16/2022] Open
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Martinello K, Giacalone E, Migliore M, Brown DA, Shah MM. The subthreshold-active K V7 current regulates neurotransmission by limiting spike-induced Ca 2+ influx in hippocampal mossy fiber synaptic terminals. Commun Biol 2019; 2:145. [PMID: 31044170 PMCID: PMC6486593 DOI: 10.1038/s42003-019-0408-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/29/2019] [Indexed: 12/23/2022] Open
Abstract
Little is known about the properties and function of ion channels that affect synaptic terminal-resting properties. One particular subthreshold-active ion channel, the Kv7 potassium channel, is highly localized to axons, but its role in regulating synaptic terminal intrinsic excitability and release is largely unexplored. Using electrophysiological recordings together with computational modeling, we found that the KV7 current was active at rest in adult hippocampal mossy fiber synaptic terminals and enhanced their membrane conductance. The current also restrained action potential-induced Ca2+ influx via N- and P/Q-type Ca2+ channels in boutons. This was associated with a substantial reduction in the spike half-width and afterdepolarization following presynaptic spikes. Further, by constraining spike-induced Ca2+ influx, the presynaptic KV7 current decreased neurotransmission onto CA3 pyramidal neurons and short-term synaptic plasticity at the mossy fiber-CA3 synapse. This is a distinctive mechanism by which KV7 channels influence hippocampal neuronal excitability and synaptic plasticity.
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Affiliation(s)
| | | | - Michele Migliore
- Institute of Biophysics, National Research Council, 90146 Palermo, Italy
| | - David A. Brown
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT UK
| | - Mala M. Shah
- UCL School of Pharmacy University College London, London, WC1N 1AX UK
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30
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Sun H, Lin AH, Ru F, Patil MJ, Meeker S, Lee LY, Undem BJ. KCNQ/M-channels regulate mouse vagal bronchopulmonary C-fiber excitability and cough sensitivity. JCI Insight 2019; 4:124467. [PMID: 30721152 DOI: 10.1172/jci.insight.124467] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/29/2019] [Indexed: 01/06/2023] Open
Abstract
Increased airway vagal sensory C-fiber activity contributes to the symptoms of inflammatory airway diseases. The KCNQ/Kv7/M-channel is a well-known determinant of neuronal excitability, yet whether it regulates the activity of vagal bronchopulmonary C-fibers and airway reflex sensitivity remains unknown. Here we addressed this issue using single-cell RT-PCR, patch clamp technique, extracellular recording of single vagal nerve fibers innervating the mouse lungs, and telemetric recording of cough in free-moving mice. Single-cell mRNA analysis and biophysical properties of M-current (IM) suggest that KCNQ3/Kv7.3 is the major M-channel subunit in mouse nodose neurons. The M-channel opener retigabine negatively shifted the voltage-dependent activation of IM, leading to membrane hyperpolarization, increased rheobase, and suppression of both evoked and spontaneous action potential (AP) firing in nodose neurons in an M-channel inhibitor XE991-sensitive manner. Retigabine also markedly suppressed the α,β-methylene ATP-induced AP firing in nodose C-fiber terminals innervating the mouse lungs, and coughing evoked by irritant gases in awake mice. In conclusion, KCNQ/M-channels play a role in regulating the excitability of vagal airway C-fibers at both the cell soma and nerve terminals. Drugs that open M-channels in airway sensory afferents may relieve the sufferings associated with pulmonary inflammatory diseases such as chronic coughing.
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Affiliation(s)
- Hui Sun
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - An-Hsuan Lin
- Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Fei Ru
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Mayur J Patil
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sonya Meeker
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lu-Yuan Lee
- Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Bradley J Undem
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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31
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Greene DL, Kosenko A, Hoshi N. Attenuating M-current suppression in vivo by a mutant Kcnq2 gene knock-in reduces seizure burden and prevents status epilepticus-induced neuronal death and epileptogenesis. Epilepsia 2018; 59:1908-1918. [PMID: 30146722 DOI: 10.1111/epi.14541] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 07/23/2018] [Accepted: 07/23/2018] [Indexed: 02/06/2023]
Abstract
OBJECTIVES The M-current is a low-threshold voltage-gated potassium current generated by Kv7 subunits that regulates neural excitation. It is important to note that M-current suppression, induced by activation of Gq-coupled neurotransmitter receptors, can dynamically regulate the threshold of action-potential firing and firing frequency. Here we sought to directly examine whether M-current suppression is involved in seizures and epileptogenesis. METHODS Kv7.2 knock-in mice lacking the key protein kinase C (PKC) phosphorylation acceptor site for M-current suppression were generated by introducing an alanine substitution at serine residue 559 of mouse Kv7.2, mKv7.2(S559A). Basic electrophysiologic properties of the M-current between wild-type and Kv7.2(S559A) knock-in mice were analyzed in primary cultured neurons. Homozygous Kv7.2(S559A) knock-in mice were used to evaluate the protective effect of mutant Kv7.2 channel against chemoconvulsant-induced seizures. In addition, pilocarpine-induced neuronal damage and spontaneously recurrent seizures were evaluated after equivalent chemoconvulsant-induced status epilepticus was achieved by coadministration of the M-current-specific channel inhibitor, XE991. RESULT Neurons from Kv7.2(S559A) knock-in mice showed normal basal M-currents. Knock-in mice displayed reduced M-current suppression when challenged by a muscarinic agonist, oxotremorine-M. Kv7.2(S559A) mice were resistant to chemoconvulsant-induced seizures with no mortality. Administration of XE991 transiently exacerbated seizures in knock-in mice equivalent to those of wild-type mice. Valproate, which disrupts neurotransmitter-induced M-current suppression, showed no additional anticonvulsant effect in Kv7.2(S559A) mice. After experiencing status epilepticus, Kv7.2(S559A) knock-in mice did not show seizure-induced cell death or spontaneous recurring seizures. SIGNIFICANCE This study provides evidence that neurotransmitter-induced suppression of M-current generated by Kv7.2-containing channels exacerbates behavioral seizures. In addition, prompt recovery of M-current after status epilepticus prevents subsequent neuronal death and the development of spontaneously recurrent seizures. Therefore, prompt restoration of M-current activity may have a therapeutic benefit for epilepsy.
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Affiliation(s)
- Derek L Greene
- Department of Pharmacology, University of California, Irvine, Irvine, California
| | - Anastasia Kosenko
- Department of Pharmacology, University of California, Irvine, Irvine, California
| | - Naoto Hoshi
- Department of Pharmacology, University of California, Irvine, Irvine, California.,Department of Physiology and Biophysics, University of California, Irvine, Irvine, California
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Dewell RB, Gabbiani F. M current regulates firing mode and spike reliability in a collision-detecting neuron. J Neurophysiol 2018; 120:1753-1764. [PMID: 30044671 DOI: 10.1152/jn.00363.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
All animals must detect impending collisions to escape and reliably discriminate them from nonthreatening stimuli, thus preventing false alarms. Therefore, it is no surprise that animals have evolved highly selective and sensitive neurons dedicated to such tasks. We examined a well-studied collision-detection neuron in the grasshopper ( Schistocerca americana) using in vivo electrophysiology, pharmacology, and computational modeling. This lobula giant movement detector (LGMD) neuron is excitable by inputs originating from each ommatidia of the compound eye. It possesses many intrinsic properties that increase its selectivity to objects approaching on a collision course, including switching between burst and nonburst firing. In this study, we demonstrate that the LGMD neuron exhibits a large M current, generated by noninactivating K+ channels, that shortens the temporal window of dendritic integration, regulates a firing mode switch between burst and isolated spiking, increases the precision of spike timing, and increases the reliability of spike propagation to downstream motor centers. By revealing how the M current increases the LGMD's ability to detect impending collisions, our results suggest that similar channels may play an analogous role in other collision detection circuits. NEW & NOTEWORTHY The ability to reliably detect impending collisions is a critical survival skill. The nervous systems of many animals have developed dedicated neurons for accomplishing this task. We used a mix of in vivo electrophysiology and computational modeling to investigate the role of M potassium channels within one such collision-detecting neuron and show that through regulation of burst firing and enhancement of spiking reliability, the M current increases the ability to detect impending collisions.
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Affiliation(s)
- Richard B Dewell
- Department of Neuroscience, Baylor College of Medicine , Houston, Texas
| | - Fabrizio Gabbiani
- Department of Neuroscience, Baylor College of Medicine , Houston, Texas.,Department of Electrical and Computer Engineering, Rice University , Houston, Texas
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33
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Yu T, Li L, Liu H, Li H, Liu Z, Li Z. KCNQ2/3/5 channels in dorsal root ganglion neurons can be therapeutic targets of neuropathic pain in diabetic rats. Mol Pain 2018; 14:1744806918793229. [PMID: 30027794 PMCID: PMC6088482 DOI: 10.1177/1744806918793229] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background Diabetic neuropathic pain is poorly controlled by analgesics, and the precise molecular mechanisms underlying hyperalgesia remain unclear. The KCNQ2/3/5 channels expressed in dorsal root ganglion neurons are important in pain transmission. The expression and activity of KCNQ2/3/5 channels in dorsal root ganglion neurons in rats with diabetic neuropathic pain were investigated in this study. Methods The mRNA levels of KCNQ2/3/5 channels were analyzed by real-time polymerase chain reaction. The protein levels of KCNQ2/3/5 channels were evaluated by Western blot assay. KCNQ2/3/5 channel expression in situ in dorsal root ganglion neurons was detected by double fluorescent labeling technique. M current (IM) density and neuronal excitability were determined by whole-cell voltage and current clamp recordings. Mechanical allodynia and thermal hyperalgesia were assessed by von Frey filaments and plantar analgesia tester, respectively. Results The mRNA and protein levels of KCNQ2/3/5 channels significantly decreased, followed by the reduction of IM density and elevation of neuronal excitability of dorsal root ganglion neurons from diabetic rats. Activation of KCNQ channels with retigabine reduced the hyperexcitability and inhibition of KCNQ channels with XE991 enhanced the hyperexcitability. Administration of retigabine alleviated both mechanical allodynia and thermal hyperalgesia, while XE991 augmented both mechanical allodynia and thermal hyperalgesia in diabetic neuropathic pain in rats. Conclusion The findings elucidate the mechanisms by which downregulation of the expression and reduction of the activity of KCNQ2/3/5 channels in diabetic rat dorsal root ganglion neurons contribute to neuronal hyperexcitability, which results in hyperalgesia. These data provide intriguing evidence that activation of KCNQ2/3/5 channels might be the potential new targets for alleviating diabetic neuropathic pain symptoms.
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Affiliation(s)
- Ting Yu
- 1 Department of Anatomy, School of Basic Medical Sciences, Shandong University, Jinan, China.,2 Department of Physiology, Jining Medical University, Jining, China
| | - Lei Li
- 3 Department of Diagnosis, Jining Medical University, Jining, China
| | - Huaxiang Liu
- 4 Department of Rheumatology, Shandong University Qilu Hospital, Jinan, China
| | - Hao Li
- 5 Department of Orthopaedics, Shandong University Qilu Hospital, Jinan, China
| | - Zhen Liu
- 1 Department of Anatomy, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Zhenzhong Li
- 1 Department of Anatomy, School of Basic Medical Sciences, Shandong University, Jinan, China
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Paz RM, Tubert C, Stahl A, Díaz AL, Etchenique R, Murer MG, Rela L. Inhibition of striatal cholinergic interneuron activity by the Kv7 opener retigabine and the nonsteroidal anti-inflammatory drug diclofenac. Neuropharmacology 2018; 137:309-321. [PMID: 29758221 DOI: 10.1016/j.neuropharm.2018.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 04/26/2018] [Accepted: 05/07/2018] [Indexed: 11/18/2022]
Abstract
Striatal cholinergic interneurons provide modulation to striatal circuits involved in voluntary motor control and goal-directed behaviors through their autonomous tonic discharge and their firing "pause" responses to novel and rewarding environmental events. Striatal cholinergic interneuron hyperactivity was linked to the motor deficits associated with Parkinson's disease and the adverse effects of chronic antiparkinsonian therapy like l-DOPA-induced dyskinesia. Here we addressed whether Kv7 channels, which provide negative feedback to excitation in other neuron types, are involved in the control of striatal cholinergic interneuron tonic activity and response to excitatory inputs. We found that autonomous firing of striatal cholinergic interneurons is not regulated by Kv7 channels. In contrast, Kv7 channels limit the summation of excitatory postsynaptic potentials in cholinergic interneurons through a postsynaptic mechanism. Striatal cholinergic interneurons have a high reserve of Kv7 channels, as their opening using pharmacological tools completely silenced the tonic firing and markedly reduced their intrinsic excitability. A strong inhibition of striatal cholinergic interneurons was also observed in response to the anti-inflammatory drugs diclofenac and meclofenamic acid, however, this effect was independent of Kv7 channels. These data bring attention to new potential molecular targets and pharmacological tools to control striatal cholinergic interneuron activity in pathological conditions where they are believed to be hyperactive, including Parkinson's disease.
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Affiliation(s)
- Rodrigo Manuel Paz
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina
| | - Cecilia Tubert
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina
| | - Agostina Stahl
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina
| | - Analía López Díaz
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina
| | - Roberto Etchenique
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Ciudad Universitaria Pabellón 2, AR1428EHA Buenos Aires, Argentina
| | - Mario Gustavo Murer
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina
| | - Lorena Rela
- Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-Houssay), Grupo de Neurociencia de Sistemas, Buenos Aires 1121, Argentina.
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Tiwari MN, Mohan S, Biala Y, Yaari Y. Differential contributions of Ca 2+ -activated K + channels and Na + /K + -ATPases to the generation of the slow afterhyperpolarization in CA1 pyramidal cells. Hippocampus 2018; 28:338-357. [PMID: 29431274 PMCID: PMC5947627 DOI: 10.1002/hipo.22836] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/17/2017] [Accepted: 02/05/2018] [Indexed: 12/13/2022]
Abstract
In many types of CNS neurons, repetitive spiking produces a slow afterhyperpolarization (sAHP), providing sustained, intrinsically generated negative feedback to neuronal excitation. Changes in the sAHP have been implicated in learning behaviors, in cognitive decline in aging, and in epileptogenesis. Despite its importance in brain function, the mechanisms generating the sAHP are still controversial. Here we have addressed the roles of M-type K+ current (IM ), Ca2+ -gated K+ currents (ICa(K) 's) and Na+ /K+ -ATPases (NKAs) current to sAHP generation in adult rat CA1 pyramidal cells maintained at near-physiological temperature (35 °C). No evidence for IM contribution to the sAHP was found in these neurons. Both ICa(K) 's and NKA current contributed to sAHP generation, the latter being the predominant generator of the sAHP, particularly when evoked with short trains of spikes. Of the different NKA isoenzymes, α1 -NKA played the key role, endowing the sAHP a steep voltage-dependence. Thus normal and pathological changes in α1 -NKA expression or function may affect cognitive processes by modulating the inhibitory efficacy of the sAHP.
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Affiliation(s)
- Manindra Nath Tiwari
- Department of Medical Neurobiology; Institute for Medical Research Israel‐CanadaThe Hebrew University‐Hadassah School of MedicineJerusalem91120Israel
| | - Sandesh Mohan
- Department of Medical Neurobiology; Institute for Medical Research Israel‐CanadaThe Hebrew University‐Hadassah School of MedicineJerusalem91120Israel
| | - Yoav Biala
- Department of Medical Neurobiology; Institute for Medical Research Israel‐CanadaThe Hebrew University‐Hadassah School of MedicineJerusalem91120Israel
| | - Yoel Yaari
- Department of Medical Neurobiology; Institute for Medical Research Israel‐CanadaThe Hebrew University‐Hadassah School of MedicineJerusalem91120Israel
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Fosmo AL, Skraastad ØB. The Kv7 Channel and Cardiovascular Risk Factors. Front Cardiovasc Med 2017; 4:75. [PMID: 29259974 PMCID: PMC5723334 DOI: 10.3389/fcvm.2017.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/21/2017] [Indexed: 12/30/2022] Open
Abstract
Potassium channels play a pivotal role in the regulation of excitability in cells such as neurons, cardiac myocytes, and vascular smooth muscle cells. The KCNQ (Kv7) family of voltage-activated K+ channels hyperpolarizes the cell and stabilizes the membrane potential. Here, we outline how Kv7 channel activity may contribute to the development of the cardiovascular risk factors such as hypertension, diabetes, and obesity. Questions and hypotheses regarding previous and future research have been raised. Alterations in the Kv7 channel may contribute to the development of cardiovascular disease (CVD). Pharmacological modification of Kv7 channels may represent a possible treatment for CVD in the future.
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Affiliation(s)
- Andreas L Fosmo
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Øyvind B Skraastad
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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