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Lale N, Ditting T, Hilgers KF, Linz P, Ott C, Schmieder RE, Schiffer M, Amann K, Veelken R, Rodionova K. Afferent neurons of the kidney with impaired firing pattern in inflammation - role of sodium currents? Pflugers Arch 2023; 475:1329-1342. [PMID: 37672108 PMCID: PMC10567872 DOI: 10.1007/s00424-023-02852-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/15/2023] [Accepted: 08/16/2023] [Indexed: 09/07/2023]
Abstract
Peripheral neurons with renal afferents exhibit a predominantly tonic firing pattern of higher frequency that is reduced to low frequencies (phasic firing pattern) in renal inflammation. We wanted to test the hypothesis that the reduction in firing activity during inflammation is due to high-activity tonic neurons switching from higher to low frequencies depending on altered sodium currents. We identified and cultivated afferent sensory neurons with renal projections from the dorsal root ganglia (Th11-L2). Cultivated neurons were incubated with the chemokine CXCL1 (1,5 nmol/ml) for 12 h. We characterized neurons as "tonic," i.e., sustained action potential (AP) firing, or "phasic," i.e., < 5 APs upon stimulation in the current clamp. Their membrane currents were investigated in a voltage clamp. Data analyzed: renal vs. non-renal and tonic vs. phasic neurons. Renal afferent neurons exposed to CXCL1 showed a decrease in tonic firing pattern (CXCL1: 35,6% vs. control: 57%, P < 0.05). Na+ and K+ currents were not different between control renal and non-renal DRG neurons. Phasic neurons exhibited higher Na+ and K+ currents than tonic resulting in shorter APs (3.7 ± 0.3 vs. 6.1 ± 0.6 ms, P < 0.01). In neurons incubated with CXCL1, Na+ and K+ peak current density increased in phasic (Na+: - 969 ± 47 vs. - 758 ± 47 nA/pF, P < 0.01; K+: 707 ± 22 vs. 558 ± 31 nA/pF, P < 0.01), but were unchanged in tonic neurons. Phasic neurons exposed to CXCL1 showed a broader range of Na+ currents ([- 365- - 1429 nA] vs. [- 412- - 4273 nA]; P < 0.05) similar to tonic neurons. After CXCL1 exposure, significant changes in phasic neurons were observed in sodium activation/inactivation as well as a wider distribution of Na+ currents characteristic of tonic neurons. These findings indicate a subgroup of tonic neurons besides mere tonic or phasic neurons exists able to exhibit a phasic activity pattern under pathological conditions.
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Affiliation(s)
- Nena Lale
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Tilmann Ditting
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
| | - Karl F Hilgers
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Peter Linz
- Department of Radiology, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Christian Ott
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
| | - Roland E Schmieder
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Mario Schiffer
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Roland Veelken
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany.
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany.
| | - Kristina Rodionova
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
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Rodionova K, Hilgers KF, Rafii-Tabrizi S, Doellner J, Cordasic N, Linz P, Karl AL, Ott C, Schmieder RE, Schiffer M, Amann K, Veelken R, Ditting T. Responsiveness of afferent renal nerve units in renovascular hypertension in rats. Pflugers Arch 2021; 473:1617-1629. [PMID: 34232378 PMCID: PMC8433106 DOI: 10.1007/s00424-021-02591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/12/2021] [Accepted: 06/03/2021] [Indexed: 12/01/2022]
Abstract
Previous data suggest that renal afferent nerve activity is increased in hypertension exerting sympathoexcitatory effects. Hence, we wanted to test the hypothesis that in renovascular hypertension, the activity of dorsal root ganglion (DRG) neurons with afferent projections from the kidneys is augmented depending on the degree of intrarenal inflammation. For comparison, a nonhypertensive model of mesangioproliferative nephritis was investigated. Renovascular hypertension (2-kidney, 1-clip [2K1C]) was induced by unilateral clipping of the left renal artery and mesangioproliferative glomerulonephritis (anti-Thy1.1) by IV injection of a 1.75-mg/kg BW OX-7 antibody. Neuronal labeling (dicarbocyanine dye [DiI]) in all rats allowed identification of renal afferent dorsal root ganglion (DRG) neurons. A current clamp was used to characterize neurons as tonic (sustained action potential [AP] firing) or phasic (1–4 AP) upon stimulation by current injection. All kidneys were investigated using standard morphological techniques. DRG neurons exhibited less often tonic response if in vivo axonal input from clipped kidneys was received (30.4% vs. 61.2% control, p < 0.05). However, if the nerves to the left clipped kidneys were cut 7 days prior to investigation, the number of tonic renal neurons completely recovered to well above control levels. Interestingly, electrophysiological properties of neurons that had in vivo axons from the right non-clipped kidneys were not distinguishable from controls. Renal DRG neurons from nephritic rats also showed less often tonic activity upon current injection (43.4% vs. 64.8% control, p < 0.05). Putative sympathoexcitatory and impaired sympathoinhibitory renal afferent nerve fibers probably contribute to increased sympathetic activity in 2K1C hypertension.
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Affiliation(s)
- Kristina Rodionova
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Karl F Hilgers
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Salman Rafii-Tabrizi
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Johannes Doellner
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Nada Cordasic
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Peter Linz
- Department of Radiology, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Anna-Lena Karl
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Christian Ott
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany.,Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
| | - Roland E Schmieder
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Mario Schiffer
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Roland Veelken
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany. .,Department of Radiology, Friedrich-Alexander University Erlangen, Erlangen, Germany.
| | - Tilmann Ditting
- Department of Internal Medicine 4 - Nephrology and Hypertension, Friedrich-Alexander University Erlangen, Erlangen, Germany.,Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
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3
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Neurogenic substance P-influences on action potential production in afferent neurons of the kidney? Pflugers Arch 2021; 473:633-646. [PMID: 33786667 PMCID: PMC8049925 DOI: 10.1007/s00424-021-02552-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 12/23/2022]
Abstract
We recently showed that a substance P (SP)–dependent sympatho-inhibitory mechanism via afferent renal nerves is impaired in mesangioproliferative nephritis. Therefore, we tested the hypothesis that SP released from renal afferents inhibits the action potential (AP) production in their dorsal root ganglion (DRG) neurons. Cultured DRG neurons (Th11-L2) were investigated in current clamp mode to assess AP generation during both TRPV1 stimulation by protons (pH 6) and current injections with and without exposure to SP (0.5 µmol) or CGRP (0.5 µmol). Neurons were classified as tonic (sustained AP generation) or phasic (≤ 4 APs) upon current injection; voltage clamp experiments were performed for the investigation of TRPV1-mediated inward currents due to proton stimulation. Superfusion of renal neurons with protons and SP increased the number of action potentials in tonic neurons (9.6 ± 5 APs/10 s vs. 16.9 ± 6.1 APs/10 s, P < 0.05, mean ± SD, n = 7), while current injections with SP decreased it (15.2 ± 6 APs/600 ms vs. 10.2 ± 8 APs/600 ms, P < 0.05, mean ± SD, n = 29). Addition of SP significantly reduced acid-induced TRPV1-mediated currents in renal tonic neurons (− 518 ± 743 pA due to pH 6 superfusion vs. − 82 ± 50 pA due to pH 6 with SP superfusion). In conclusion, SP increased action potential production via a TRPV1-dependent mechanism in acid-sensitive renal neurons. On the other hand, current injection in the presence of SP led to decreased action potential production. Thus, the peptide SP modulates signaling pathways in renal neurons in an unexpected manner leading to both stimulation and inhibition of renal neuronal activity in different (e.g., acidic) environmental contexts.
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Rodionova K, Veelken R, Hilgers KF, Paulus EM, Linz P, Fischer MJM, Schenker M, Reeh P, Tiegs G, Ott C, Schmieder R, Schiffer M, Amann K, Ditting T. Afferent renal innervation in anti-Thy1.1 nephritis in rats. Am J Physiol Renal Physiol 2020; 319:F822-F832. [PMID: 33017188 DOI: 10.1152/ajprenal.00063.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Afferent renal nerves exhibit a dual function controlling central sympathetic outflow via afferent electrical activity and influencing intrarenal immunological processes by releasing peptides such as calcitonin gene-related peptide (CGRP). We tested the hypothesis that increased afferent and efferent renal nerve activity occur with augmented release of CGRP in anti-Thy1.1 nephritis, in which enhanced CGRP release exacerbates inflammation. Nephritis was induced in Sprague-Dawley rats by intravenous injection of OX-7 antibody (1.75 mg/kg), and animals were investigated neurophysiologically, electrophysiologically, and pathomorphologically 6 days later. Nephritic rats exhibited proteinuria (169.3 ± 10.2 mg/24 h) with increased efferent renal nerve activity (14.7 ± 0.9 bursts/s vs. control 11.5 ± 0.9 bursts/s, n = 11, P < 0.05). However, afferent renal nerve activity (in spikes/s) decreased in nephritis (8.0 ± 1.8 Hz vs. control 27.4 ± 4.1 Hz, n = 11, P < 0.05). In patch-clamp recordings, neurons with renal afferents from nephritic rats showed a lower frequency of high activity following electrical stimulation (43.4% vs. 66.4% in controls, P < 0.05). In vitro assays showed that renal tissue from nephritic rats exhibited increased CGRP release via spontaneous (14 ± 3 pg/mL vs. 6.8 ± 2.8 pg/ml in controls, n = 7, P < 0.05) and stimulated mechanisms. In nephritic animals, marked infiltration of macrophages in the interstitium (26 ± 4 cells/mm2) and glomeruli (3.7 ± 0.6 cells/glomerular cross-section) occurred. Pretreatment with the CGRP receptor antagonist CGRP8-37 reduced proteinuria, infiltration, and proliferation. In nephritic rats, it can be speculated that afferent renal nerves lose their ability to properly control efferent sympathetic nerve activity while influencing renal inflammation through increased CGRP release.
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Affiliation(s)
- Kristina Rodionova
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany
| | - Roland Veelken
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany.,Department of Internal Medicine 4 (Nephrology und Hypertension), Paracelsus Private Medical School, Klinikum Nuremberg, Nuremberg, Germany
| | - Karl F Hilgers
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany
| | - Eva-Maria Paulus
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany
| | - Peter Linz
- Department of Radiology, University of Erlangen, Erlangen, Germany
| | - Michael J M Fischer
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Martina Schenker
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany.,Department of Physiology and Pathophysiology, University Erlangen, Erlangen, Germany
| | - Peter Reeh
- Department of Physiology and Pathophysiology, University Erlangen, Erlangen, Germany
| | - Gisa Tiegs
- Center of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Ott
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany.,Department of Internal Medicine 4 (Nephrology und Hypertension), Paracelsus Private Medical School, Klinikum Nuremberg, Nuremberg, Germany
| | - Roland Schmieder
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany
| | - Mario Schiffer
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, University of Erlangen, Erlangen, Germany
| | - Tilmann Ditting
- Department of Internal Medicine 4 (Nephrology und Hypertension), University of Erlangen, Erlangen, Germany.,Department of Internal Medicine 4 (Nephrology und Hypertension), Paracelsus Private Medical School, Klinikum Nuremberg, Nuremberg, Germany
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5
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Ong J, Kinsman BJ, Sved AF, Rush BM, Tan RJ, Carattino MD, Stocker SD. Renal sensory nerves increase sympathetic nerve activity and blood pressure in 2-kidney 1-clip hypertensive mice. J Neurophysiol 2019; 122:358-367. [PMID: 31091159 DOI: 10.1152/jn.00173.2019] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Renal denervation lowers arterial blood pressure (ABP) in multiple clinical trials and some experimental models of hypertension. These antihypertensive effects have been attributed to the removal of renal afferent nerves. The purpose of the present study was to define the function, anatomy, and contribution of mouse renal sensory neurons to a renal nerve-dependent model of hypertension. First, electrical stimulation of mouse renal afferent nerves produced frequency-dependent increases in ABP that were eliminated by ganglionic blockade. Stimulus-triggered averaging revealed renal afferent stimulation significantly increased splanchnic, renal, and lumbar sympathetic nerve activity (SNA). Second, kidney injection of wheat germ agglutinin into male C57Bl6 mice (12-14 wk; Jackson Laboratories) produced ipsilateral labeling in the T11-L2 dorsal root ganglia. Next, 2-kidney 1-clip (2K1C) hypertension was produced in male C57Bl6 mice (12-14 wk; Jackson Laboratories) by placement of a 0.5-mm length of polytetrafluoroethylene tubing around the left renal artery. 2K1C mice displayed an elevated ABP measured via telemetry and a greater fall in mean ABP to ganglionic blockade at day 14 or 21 vs. day 0. Renal afferent discharge was significantly higher in 2K1C-clipped vs. 2K1C-unclipped or sham kidneys. In addition, 2K1C-clipped vs. 2K1C-unclipped or sham kidneys had lower renal mass and higher mRNA levels of several proinflammatory cytokines. Finally, both ipsilateral renal denervation (10% phenol) or selective denervation of renal afferent nerves (periaxonal application of 33 mM capsaicin) at time of clipping resulted in lower ABP of 2K1C mice at day 14 or 21. These findings suggest mouse renal sensory neurons are activated to increase SNA and ABP in 2K1C hypertension. NEW & NOTEWORTHY This study documents the function, anatomy, and contribution of mouse renal sensory nerves to neurogenic hypertension produced by renal stenosis. Activation of renal afferents increased sympathetic nerve activity and blood pressure. Renal afferent activity was elevated in hypertensive mice, and renal afferent denervation lowered blood pressure. Clinically, patients with renal stenosis have been excluded from clinical trials for renal denervation, but this study highlights the potential therapeutic efficacy to target renal nerves in these patients.
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Affiliation(s)
- Jason Ong
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Brian J Kinsman
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Alan F Sved
- Department of Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Brittney M Rush
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Roderick J Tan
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Marcelo D Carattino
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
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Boente-Juncal A, Vale C, Cifuentes M, Otero P, Camiña M, Rodriguez-Vieytes M, Botana LM. Chronic In Vivo Effects of Repeated Exposure to Low Oral Doses of Tetrodotoxin: Preliminary Evidence of Nephrotoxicity and Cardiotoxicity. Toxins (Basel) 2019; 11:E96. [PMID: 30736354 PMCID: PMC6410189 DOI: 10.3390/toxins11020096] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/22/2019] [Accepted: 02/01/2019] [Indexed: 11/24/2022] Open
Abstract
Tetrodotoxin (TTX) is one of the most potent naturally occurring neurotoxins. InitiallyTTX was associated with human food intoxications in Japan, but nowadays, concerns about thehuman health risks posed by TTX have increased in Europe after the identification of the toxin infish, marine gastropods, and bivalves captured in European waters. Even when TTX monitoring isnot currently performed in Europe, an acute oral no observable effect level (NOAEL) of 75 μg/kghas been recently established but, to date, no studies evaluating the chronic oral toxicity of TTXhave been released, even when EFSA has highlighted the need for them. Thus, in this work, thechronic effects of low oral TTX doses (below the acute lethal dose 50) were evaluated followinginternationally adopted guidelines. The results presented here demonstrate that low oral doses ofTTX have deleterious effects on renal and cardiac tissues. Moreover, alterations in bloodbiochemistry parameters, urine production, and urinalysis data were already detected at the oraldose of 75 μg/kg after the 28 days exposure. Thus, the data presented here constitute an initialapproach for the chronic evaluation of the in vivo toxicity of tetrodotoxin after its ingestion throughcontaminated fishery products.
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Affiliation(s)
- Andrea Boente-Juncal
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Carmen Vale
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Manuel Cifuentes
- Departamento de Anatomía, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Paz Otero
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Mercedes Camiña
- Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Mercedes Rodriguez-Vieytes
- Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
| | - Luis Miguel Botana
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
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Kaneko K, Soty M, Zitoun C, Duchampt A, Silva M, Philippe E, Gautier-Stein A, Rajas F, Mithieux G. The role of kidney in the inter-organ coordination of endogenous glucose production during fasting. Mol Metab 2018; 16:203-212. [PMID: 29960865 PMCID: PMC6157617 DOI: 10.1016/j.molmet.2018.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/04/2018] [Accepted: 06/13/2018] [Indexed: 11/15/2022] Open
Abstract
Objective The respective contributions to endogenous glucose production (EGP) of the liver, kidney and intestine vary during fasting. We previously reported that the deficiency in either hepatic or intestinal gluconeogenesis modulates the repartition of EGP via glucagon secretion (humoral factor) and gut–brain–liver axis (neural factor), respectively. Considering renal gluconeogenesis reportedly accounted for approximately 50% of EGP during fasting, we examined whether a reduction in renal gluconeogenesis could promote alterations in the repartition of EGP in this situation. Methods We studied mice whose glucose-6-phosphatase (G6Pase) catalytic subunit (G6PC) is specifically knocked down in the kidneys (K-G6pc-/- mice) during fasting. We also examined the additional effects of intestinal G6pc deletion, renal denervation and vitamin D administration on the altered glucose metabolism in K-G6pc-/- mice. Results Compared with WT mice, K-G6pc-/- mice exhibited (1) lower glycemia, (2) enhanced intestinal but not hepatic G6Pase activity, (3) enhanced hepatic glucokinase (GK encoded by Gck) activity, (4) increased hepatic glucose-6-phosphate and (5) hepatic glycogen spared from exhaustion during fasting. Increased hepatic Gck expression in the post-absorptive state could be dependent on the enhancement of insulin signal (AKT phosphorylation) in K-G6pc-/- mice. In contrast, the increase in hepatic GK activity was not observed in mice with both kidney- and intestine-knockout (KI-G6pc-/- mice). Hepatic Gck gene expression and hepatic AKT phosphorylation were reduced in KI-G6pc-/- mice. Renal denervation by capsaicin did not induce any effect on glucose metabolism in K-G6pc-/- mice. Plasma level of 1,25 (OH)2 D3, an active form of vitamin D, was decreased in K-G6pc-/- mice. Interestingly, the administration of 1,25 (OH)2 D3 prevented the enhancement of intestinal gluconeogenesis and hepatic GK activity and blocked the accumulation of hepatic glycogen otherwise observed in K-G6pc-/- mice during fasting. Conclusions A diminution in renal gluconeogenesis that is accompanied by a decrease in blood vitamin D promotes a novel repartition of EGP among glucose producing organs during fasting, featured by increased intestinal gluconeogenesis that leads to sparing glycogen stores in the liver. Our data suggest a possible involvement of a crosstalk between the kidneys and intestine (via the vitamin D system) and the intestine and liver (via a neural gut-brain axis), which might take place in the situations of deficient renal glucose production, such as chronic kidney disease. Reduced renal G6Pase activity promotes increased hepatic glycogen during fasting. Reduced renal G6Pase activity enhances intestinal but not hepatic G6Pase activity. Reduced renal G6Pase activity results in low vitamin D level. Vitamin D injection restores metabolism in mice with reduced renal G6Pase activity.
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Affiliation(s)
- Keizo Kaneko
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France.
| | - Maud Soty
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Carine Zitoun
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Adeline Duchampt
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Marine Silva
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Erwann Philippe
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Amandine Gautier-Stein
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Fabienne Rajas
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France
| | - Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, F-69008, France; Université de Lyon, Lyon, F-69008, France; Université Lyon1, Villeurbanne, F-69622, France.
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8
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de Moraes ER, Kushmerick C, Naves LA. Morphological and functional diversity of first-order somatosensory neurons. Biophys Rev 2017; 9:847-856. [PMID: 28889335 DOI: 10.1007/s12551-017-0321-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Accepted: 08/24/2017] [Indexed: 01/01/2023] Open
Abstract
First-order somatosensory neurons transduce and convey information about the external or internal environment of the body to the central nervous system. They are pseudo unipolar neurons with cell bodies residing in one of several ganglia located near the central nervous system, with the short branch of the axon connecting to the spinal cord or the brain stem and the long branch extending towards the peripheral organ they innervate. Besides their sensory transducer and conductive role, somatosensory neurons also have trophic functions in the tissue they innervate and participate in local reflexes in the periphery. The cell bodies of these neurons are remarkably diverse in terms of size, molecular constitution, and electrophysiological properties. These parameters have provided criteria for classification that have proved useful to establish and study their functions. In this review, we discuss ways to measure and classify populations of neurons based on their size and action potential firing pattern. We also discuss attempts to relate the different populations to specific sensory modalities.
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Affiliation(s)
- Eder Ricardo de Moraes
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, São Cristóvão, Sergipe, Brazil
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Lígia Araujo Naves
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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9
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Skrzypecki J, Ufnal M. Drug resistant hypertension – no simple way out. Kidney Blood Press Res 2016; 40:66-76. [PMID: 25791632 DOI: 10.1159/000368483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 11/19/2022] Open
Abstract
Hypertension poses growing challenge for health policy-makers and doctors worldwide. Recently published results of Symplicity-III trial (HTN-3), the first blinded, randomized, multicenter study on the efficacy of renal denervation for the treatment of resistant hypertension did not show a significant reduction of BP in patients with resistant hypertension 6 months after renal-artery denervation, as compared with controls. In this paper we review clinical and experimental studies on renal denervation. In order to identify causes of inconsistent results in renal denervation studies we look at basic science support for renal denervation and at designs of clinical trials.
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10
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Ditting T, Freisinger W, Rodionova K, Schatz J, Lale N, Heinlein S, Linz P, Ott C, Schmieder RE, Scrogin KE, Veelken R. Impaired excitability of renal afferent innervation after exposure to the inflammatory chemokine CXCL1. Am J Physiol Renal Physiol 2015; 310:F364-71. [PMID: 26697980 DOI: 10.1152/ajprenal.00189.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 12/15/2015] [Indexed: 01/06/2023] Open
Abstract
Recently, we showed that renal afferent neurons exhibit a unique firing pattern, i.e., predominantly sustained firing, upon stimulation. Pathological conditions such as renal inflammation likely alter excitability of renal afferent neurons. Here, we tested whether the proinflammatory chemokine CXCL1 alters the firing pattern of renal afferent neurons. Rat dorsal root ganglion neurons (Th11-L2), retrogradely labeled with dicarbocyanine dye, were incubated with CXCL1 (20 h) or vehicle before patch-clamp recording. The firing pattern of neurons was characterized as tonic, i.e., sustained action potential (AP) firing, or phasic, i.e., <5 APs following current injection. Of the labeled renal afferents treated with vehicle, 58.9% exhibited a tonic firing pattern vs. 7.8%, in unlabeled, nonrenal neurons (P < 0.05). However, after exposure to CXCL1, significantly more phasic neurons were found among labeled renal neurons; hence the occurrence of tonic neurons with sustained firing upon electrical stimulation decreased (35.6 vs. 58.9%, P < 0.05). The firing frequency among tonic neurons was not statistically different between control and CXCL1-treated neurons. However, the lower firing frequency of phasic neurons was even further decreased with CXCL1 exposure [control: 1 AP/600 ms (1-2) vs. CXCL1: 1 AP/600 ms (1-1); P < 0.05; median (25th-75th percentile)]. Hence, CXCL1 shifted the firing pattern of renal afferents from a predominantly tonic to a more phasic firing pattern, suggesting that CXCL1 reduced the sensitivity of renal afferent units upon stimulation.
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Affiliation(s)
- Tilmann Ditting
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Wolfgang Freisinger
- Department of Internal Medicine 1, Nephrology Johannes-Guttenberg University, Mainz, Germany
| | - Kristina Rodionova
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Johannes Schatz
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Nena Lale
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Sonja Heinlein
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Peter Linz
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Christian Ott
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Roland E Schmieder
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany
| | - Karie E Scrogin
- Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago Stritch School of Medicine, Chicago, Illinois
| | - Roland Veelken
- Department of Internal Medicine 4, Nephrology and Hypertension, Friedrich-Alexander University, Erlangen, Germany;
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Pattern of Functional TTX-Resistant Sodium Channels Reveals a Developmental Stage of Human iPSC- and ESC-Derived Nociceptors. Stem Cell Reports 2015; 5:305-13. [PMID: 26321143 PMCID: PMC4618592 DOI: 10.1016/j.stemcr.2015.07.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 12/19/2022] Open
Abstract
Human pluripotent stem cells (hPSCs) offer the opportunity to generate neuronal cells, including nociceptors. Using a chemical-based approach, we generated nociceptive sensory neurons from HUES6 embryonic stem cells and retrovirally reprogrammed induced hPSCs derived from fibroblasts. The nociceptive neurons expressed respective markers and showed tetrodotoxin-sensitive (TTXs) and -resistant (TTXr) voltage-gated sodium currents in patch-clamp experiments. In contrast to their counterparts from rodent dorsal root ganglia, TTXr currents of hPSC-derived nociceptors unexpectedly displayed a significantly more hyperpolarized voltage dependence of activation and fast inactivation. This apparent discrepancy is most likely due to a substantial expression of the developmentally important sodium channel NAV1.5. In view of the obstacles to recapitulate neuropathic pain in animal models, our data advance hPSC-derived nociceptors as a better model to study developmental and pathogenetic processes in human nociceptive neurons and to develop more specific small molecules to attenuate pain.
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