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Martin C, Stoffer C, Mohammadi M, Hugo J, Leipold E, Oehler B, Rittner HL, Blum R. Na V1.9 Potentiates Oxidized Phospholipid-Induced TRP Responses Only under Inflammatory Conditions. Front Mol Neurosci 2018; 11:7. [PMID: 29410612 PMCID: PMC5787077 DOI: 10.3389/fnmol.2018.00007] [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] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/08/2018] [Indexed: 12/13/2022] Open
Abstract
Oxidized phospholipids (OxPL) like oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) were recently identified as novel proalgesic targets in acute and chronic inflammatory pain. These endogenous chemical irritants are generated in inflamed tissue and mediate their pain-inducing function by activating the transient receptor potential channels TRPA1 and TRPV1 expressed in sensory neurons. Notably, prototypical therapeutics interfering with OxPL were shown to inhibit TRP channel activation and pain behavior. Here, we asked how OxPL excite primary sensory neurons of dorsal root ganglia (DRG neurons from mice of either sex). Acute stimulation of sensory neurons with the prototypical OxPL 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine (PGPC) evoked repetitive calcium spikes in small-diameter neurons. As NaV1.9, a voltage-gated sodium channel involved in nociceptor excitability, was previously shown to be essential for the generation of calcium spikes in motoneurons, we asked if this channel is also important for OxPL mediated calcium spike and action potential generation in nociceptors. In wild-type and NaV1.9-deficient neurons, the action potential firing rate and the calcium spike frequency to an acute PGPC stimulus was similar. When preincubated with inflammatory mediators, both, the action potential firing rate and the calcium spike frequency were markedly increased in response to an acute PGPC stimulus. However, this potentiating effect was completely lost in NaV1.9-deficient small-diameter neurons. After treatment with inflammatory mediators, the resting membrane potential of NaV1.9 KO neurons was slightly more negative than that of wild-type control neurons. This suggests that NaV1.9 channels are active under this condition and therefore increases the ease with which action potentials are elicited after OxPL stimulation. In summary, our data suggest that NaV1.9 has a switch function to potentiate the receptor potentials induced by OxPL under inflammatory conditions. Since human NaV1.9 has been shown to mediate painful and painless channelopathies, this study provides new insights into the mechanism by which NaV1.9 amplifies stimuli of endogenous irritants under inflammatory conditions.
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Affiliation(s)
- Corinna Martin
- Institute of Clinical Neurobiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.,Department of Anesthesiology, University Hospital Würzburg, Würzburg, Germany
| | - Carolin Stoffer
- Institute of Clinical Neurobiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Milad Mohammadi
- Institute of Clinical Neurobiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.,Department of Anesthesiology, University Hospital Würzburg, Würzburg, Germany
| | - Julian Hugo
- Institute of Clinical Neurobiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.,Department of Anesthesiology, University Hospital Würzburg, Würzburg, Germany
| | - Enrico Leipold
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, Jena, Germany
| | - Beatrice Oehler
- Department of Anesthesiology, University Hospital Würzburg, Würzburg, Germany
| | - Heike L Rittner
- Department of Anesthesiology, University Hospital Würzburg, Würzburg, Germany
| | - Robert Blum
- Institute of Clinical Neurobiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
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Translational Model Systems for Complex Sodium Channel Pathophysiology in Pain. Handb Exp Pharmacol 2018; 246:355-369. [PMID: 29374838 DOI: 10.1007/164_2017_91] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Chronic pain patients are often left with insufficient treatment as the pathophysiology especially of neuropathic pain remains enigmatic. Recently, genetic variations in the genes of the voltage-gated sodium channels (Navs) were linked to inherited neuropathic pain syndromes, opening a research pathway to foster our understanding of the pathophysiology of neuropathic pain. More than 10 years ago, the rare, inherited pain syndrome erythromelalgia was linked to mutations in the subtype Nav1.7, and since then a plethora of mutations and genetic variations in this and other Nav genes were identified. Often the biophysical changes induced by the genetic alteration offer a straightforward explanation for the clinical symptoms, but mutations in some channels, especially Nav1.9, paint a more complex picture. Although efforts were undertaken to significantly advance our knowledge, translation from heterologous or animal model systems to humans remains a challenge. Here we present recent advances in translation using stem cell-derived human sensory neurons and their potential application for identification of better, effective, and more precise treatment for the individual pain patient.
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Zhou X, Xiao Z, Xu Y, Zhang Y, Tang D, Wu X, Tang C, Chen M, Shi X, Chen P, Liang S, Liu Z. Electrophysiological and Pharmacological Analyses of Na v1.9 Voltage-Gated Sodium Channel by Establishing a Heterologous Expression System. Front Pharmacol 2017; 8:852. [PMID: 29213238 PMCID: PMC5702848 DOI: 10.3389/fphar.2017.00852] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/07/2017] [Indexed: 11/13/2022] Open
Abstract
Nav1. 9 voltage-gated sodium channel is preferentially expressed in peripheral nociceptive neurons. Recent progresses have proved its role in pain sensation, but our understanding of Nav1.9, in general, has lagged behind because of limitations in heterologous expression in mammal cells. In this work, functional expression of human Nav1.9 (hNav1.9) was achieved by fusing GFP to the C-terminal of hNav1.9 in ND7/23 cells, which has been proved to be a reliable method to the electrophysiological and pharmacological studies of hNav1.9. By using the hNav1.9 expression system, we investigated the electrophysiological properties of four mutations of hNav1.9 (K419N, A582T, A842P, and F1689L), whose electrophysiological functions have not been determined yet. The four mutations significantly caused positive shift of the steady-state fast inactivation and therefore increased hNav1.9 activity, consistent with the phenotype of painful peripheral neuropathy. Meanwhile, the effects of inflammatory mediators on hNav1.9 were also investigated. Impressively, histamine was found for the first time to enhance hNav1.9 activity, indicating its vital role in hNav1.9 modulating inflammatory pain. Taken together, our research provided a useful platform for hNav1.9 studies and new insight into mechanism of hNav1.9 linking to pain.
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Affiliation(s)
- Xi Zhou
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhen Xiao
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Yan Xu
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Yunxiao Zhang
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Dongfang Tang
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xinzhou Wu
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Cheng Tang
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.,Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Minzhi Chen
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.,Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiaoliu Shi
- Laboratory of Clinical Diagnosis and Research, Department of Medical Genetics, Second Xiangya Hospital of Central South University, Changsha, China
| | - Ping Chen
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.,Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Songping Liang
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.,Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhonghua Liu
- National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.,Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, China
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