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Kamei T, Kudo T, Yamane H, Ishibashi F, Takada Y, Honda S, Maezawa Y, Ikeda K, Oyamada Y. Unique electrophysiological property of a novel Nav1.7, Nav1.8, and Nav1.9 sodium channel blocker, ANP-230. Biochem Biophys Res Commun 2024; 721:150126. [PMID: 38776832 DOI: 10.1016/j.bbrc.2024.150126] [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: 02/10/2024] [Revised: 04/28/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Voltage-gated sodium channel subtypes, Nav1.7, Nav1.8, and Nav1.9 are predominantly expressed in peripheral sensory neurons. Recent genetic studies have revealed that they are involved in pathological pain processing and that the blockade of Nav1.7, Nav1.8, or Nav1.9 will become a promising pharmacotherapy especially for neuropathic pain. A growing number of drug discovery programs have targeted either of the subtypes to obtain a selective inhibitor which can provide pain relief without affecting the cardiovascular and central nervous systems, though none of them has been approved yet. Here we describe the in vitro characteristics of ANP-230, a novel sodium channel blocker under clinical development. Surprisingly, ANP-230 was shown to block three pain-related subtypes, human Nav1.7, Nav1.8, and Nav1.9 with similar potency, but had only low inhibitory activity to human cardiac Nav1.5 channel and rat central Nav channels. The voltage clamp experiments using different step pulse protocols revealed that ANP-230 had a "tonic block" mode of action without state- and use-dependency. In addition, ANP-230 caused a depolarizing shift of the activation curve and decelerated gating kinetics in human Nav1.7-stably expressing cells. The depolarizing shift of activation curve was commonly observed in human Nav1.8-stably expressing cells as well as rat dorsal root ganglion neurons. These data suggested a quite unique mechanism of Nav channel inhibition by ANP-230. Finally, ANP-230 reduced excitability of rat dorsal root ganglion neurons in a concentration dependent manner. Collectively, these promising results indicate that ANP-230 could be a potent drug for neuropathic pain.
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Affiliation(s)
- Tatsuya Kamei
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co., Ltd., Kobe, 650-0047, Japan.
| | - Takehiro Kudo
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan
| | - Hana Yamane
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co., Ltd., Kobe, 650-0047, Japan
| | - Fumiaki Ishibashi
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Platform Technology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan
| | - Yoshinori Takada
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Global Corporate Strategy, Sumitomo Pharma Co., Ltd., Tokyo, 104-8356, Japan
| | - Shigeyuki Honda
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Sumika Chemical Analysis Service, Ltd., Osaka, 554-0022, Japan
| | - Yasuyo Maezawa
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan
| | - Kazuhito Ikeda
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; Platform Technology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan
| | - Yoshihiro Oyamada
- Pharmacology Research Unit, Research Division, Sumitomo Pharma Co., Ltd., Osaka, 554-0022, Japan; AlphaNavi Pharma Inc., Osaka, 564-0053, Japan
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Zang Y, Marder E, Marom S. Sodium channel slow inactivation normalizes firing in axons with uneven conductance distributions. Curr Biol 2023; 33:1818-1824.e3. [PMID: 37023754 PMCID: PMC10175232 DOI: 10.1016/j.cub.2023.03.043] [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: 12/27/2022] [Revised: 02/17/2023] [Accepted: 03/15/2023] [Indexed: 04/08/2023]
Abstract
The Na+ channels that are important for action potentials show rapid inactivation, a state in which they do not conduct, although the membrane potential remains depolarized.1,2 Rapid inactivation is a determinant of millisecond-scale phenomena, such as spike shape and refractory period. Na+ channels also inactivate orders of magnitude more slowly, and this slow inactivation has impacts on excitability over much longer timescales than those of a single spike or a single inter-spike interval.3,4,5,6,7,8,9,10 Here, we focus on the contribution of slow inactivation to the resilience of axonal excitability11,12 when ion channels are unevenly distributed along the axon. We study models in which the voltage-gated Na+ and K+ channels are unevenly distributed along axons with different variances, capturing the heterogeneity that biological axons display.13,14 In the absence of slow inactivation, many conductance distributions result in spontaneous tonic activity. Faithful axonal propagation is achieved with the introduction of Na+ channel slow inactivation. This "normalization" effect depends on relations between the kinetics of slow inactivation and the firing frequency. Consequently, neurons with characteristically different firing frequencies will need to implement different sets of channel properties to achieve resilience. The results of this study demonstrate the importance of the intrinsic biophysical properties of ion channels in normalizing axonal function.
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Affiliation(s)
- Yunliang Zang
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA.
| | - Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA
| | - Shimon Marom
- Technion - Israel Institute of Technology, Haifa 32000, Israel
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Jo S, Zhang HXB, Bean BP. Use-Dependent Relief of Inhibition of Nav1.8 Channels by A-887826. Mol Pharmacol 2023; 103:221-229. [PMID: 36635052 PMCID: PMC10029820 DOI: 10.1124/molpharm.122.000593] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/31/2022] [Accepted: 12/09/2022] [Indexed: 01/13/2023] Open
Abstract
Sodium channel inhibitors used as local anesthetics, antiarrhythmics, or antiepileptics typically have the property of use-dependent inhibition, whereby inhibition is enhanced by repetitive channel activation. For targeting pain, Nav1.8 channels are an attractive target because they are prominent in primary pain-sensing neurons, with little or no expression in most other kinds of neurons, and a number of Nav1.8-targeted compounds have been developed. We examined the characteristics of Nav1.8 inhibition by one of the most potent Nav1.8 inhibitors so far described, A-887826, and found that when studied with physiologic resting potentials and physiologic temperatures, inhibition had strong "reverse use dependence", whereby inhibition was relieved by repetitive short depolarizations. This effect was much stronger with A-887826 than with A-803467, another Nav1.8 inhibitor. The use-dependent relief from inhibition was seen in both human Nav1.8 channels studied in a cell line and in native Nav1.8 channels in mouse dorsal root ganglion (DRG) neurons. In native Nav1.8 channels, substantial relief of inhibition occurred during repetitive stimulation by action potential waveforms at 5 Hz, suggesting that the phenomenon is likely important under physiologic conditions. SIGNIFICANCE STATEMENT: Nav1.8 sodium channels are expressed in primary pain-sensing neurons and are a prime current target for new drugs for pain. This work shows that one of the most potent Nav1.8 inhibitors, A-887826, has the unusual property that inhibition is relieved by repeated short depolarizations. This "reverse use dependence" may reduce inhibition during physiological firing and should be selected against in drug development.
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Affiliation(s)
- Sooyeon Jo
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
| | | | - Bruce P Bean
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
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Ghovanloo MR, Dib-Hajj SD, Goodchild SJ, Ruben PC, Waxman SG. Non-psychotropic phytocannabinoid interactions with voltage-gated sodium channels: An update on cannabidiol and cannabigerol. Front Physiol 2022; 13:1066455. [PMID: 36439273 PMCID: PMC9691960 DOI: 10.3389/fphys.2022.1066455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 10/31/2022] [Indexed: 09/10/2023] Open
Abstract
Phytocannabinoids, found in the plant, Cannabis sativa, are an important class of natural compounds with physiological effects. These compounds can be generally divided into two classes: psychoactive and non-psychoactive. Those which do not impart psychoactivity are assumed to predominantly function via endocannabinoid receptor (CB) -independent pathways and molecular targets, including other receptors and ion channels. Among these targets, the voltage-gated sodium (Nav) channels are particularly interesting due to their well-established role in electrical signalling in the nervous system. The interactions between the main non-psychoactive phytocannabinoid, cannabidiol (CBD), and Nav channels were studied in detail. In addition to CBD, cannabigerol (CBG), is another non-psychoactive molecule implicated as a potential therapeutic for several conditions, including pain via interactions with Nav channels. In this mini review, we provide an update on the interactions of Nav channels with CBD and CBG.
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Affiliation(s)
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
| | - Samuel J. Goodchild
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., Burnaby, BC, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
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Contribution of tetrodotoxin-resistant persistent Na + currents to the excitability of C-type dural afferent neurons in rats. J Headache Pain 2022; 23:73. [PMID: 35764917 PMCID: PMC9238149 DOI: 10.1186/s10194-022-01443-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/20/2022] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Growing evidence supports the important role of persistent sodium currents (INaP) in the neuronal excitability of various central neurons. However, the role of tetrodotoxin-resistant (TTX-R) Na+ channel-mediated INaP in the neuronal excitability of nociceptive neurons remains poorly understood. METHODS We investigated the functional role of TTX-R INaP in the excitability of C-type nociceptive dural afferent neurons, which was identified using a fluorescent dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchloride (DiI), and a whole-cell patch-clamp technique. RESULTS TTX-R INaP were found in most DiI-positive neurons, but their density was proportional to neuronal size. Although the voltage dependence of TTX-R Na+ channels did not differ among DiI-positive neurons, the extent of the onset of slow inactivation, recovery from inactivation, and use-dependent inhibition of these channels was highly correlated with neuronal size and, to a great extent, the density of TTX-R INaP. In the presence of TTX, treatment with a specific INaP inhibitor, riluzole, substantially decreased the number of action potentials generated by depolarizing current injection, suggesting that TTX-R INaP are related to the excitability of dural afferent neurons. In animals treated chronically with inflammatory mediators, the density of TTX-R INaP was significantly increased, and it was difficult to inactivate TTX-R Na+ channels. CONCLUSIONS TTX-R INaP apparently contributes to the differential properties of TTX-R Na+ channels and neuronal excitability. Consequently, the selective modulation of TTX-R INaP could be, at least in part, a new approach for the treatment of migraine headaches.
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George K, Lopez-Mateos D, Abd El-Aziz TM, Xiao Y, Kline J, Bao H, Raza S, Stockand JD, Cummins TR, Fornelli L, Rowe MP, Yarov-Yarovoy V, Rowe AH. Structural and Functional Characterization of a Novel Scorpion Toxin that Inhibits NaV1.8 via Interactions With the DI Voltage Sensor and DII Pore Module. Front Pharmacol 2022; 13:846992. [PMID: 35662692 PMCID: PMC9160825 DOI: 10.3389/fphar.2022.846992] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 04/05/2022] [Indexed: 11/30/2022] Open
Abstract
Voltage-gated sodium channel NaV1.8 regulates transmission of pain signals to the brain. While NaV1.8 has the potential to serve as a drug target, the molecular mechanisms that shape NaV1.8 gating are not completely understood, particularly mechanisms that couple activation to inactivation. Interactions between toxin producing animals and their predators provide a novel approach for investigating NaV structure-function relationships. Arizona bark scorpions produce Na+ channel toxins that initiate pain signaling. However, in predatory grasshopper mice, toxins inhibit NaV1.8 currents and block pain signals. A screen of synthetic peptide toxins predicted from bark scorpion venom showed that peptide NaTx36 inhibited Na+ current recorded from a recombinant grasshopper mouse NaV1.8 channel (OtNaV1.8). Toxin NaTx36 hyperpolarized OtNaV1.8 activation, steady-state fast inactivation, and slow inactivation. Mutagenesis revealed that the first gating charge in the domain I (DI) S4 voltage sensor and an acidic amino acid (E) in the DII SS2 – S6 pore loop are critical for the inhibitory effects of NaTx36. Computational modeling showed that a DI S1 – S2 asparagine (N) stabilizes the NaTx36 – OtNaV1.8 complex while residues in the DI S3 – S4 linker and S4 voltage sensor form electrostatic interactions that allow a toxin glutamine (Q) to contact the first S4 gating charge. Surprisingly, the models predicted that NaTx36 contacts amino acids in the DII S5 – SS1 pore loop instead of the SS2 – S6 loop; the DII SS2 – S6 loop motif (QVSE) alters the conformation of the DII S5 – SS1 pore loop, enhancing allosteric interactions between toxin and the DII S5 – SS1 pore loop. Few toxins have been identified that modify NaV1.8 gating. Moreover, few toxins have been described that modify sodium channel gating via the DI S4 voltage sensor. Thus, NaTx36 and OtNaV1.8 provide tools for investigating the structure-activity relationship between channel activation and inactivation gating, and the connection to alternative pain phenotypes.
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Affiliation(s)
- Kiran George
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Diego Lopez-Mateos
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
| | - Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX, United States
- Zoology Department, Faculty of Science, Minia University, El-Minia, Egypt
- Amsaal Venom Farm L.L.C., Abu Dhabi, United Arab Emirates
| | - Yucheng Xiao
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Jake Kline
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Hong Bao
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Syed Raza
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - James D. Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX, United States
| | - Theodore R. Cummins
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Luca Fornelli
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Matthew P. Rowe
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
| | - Ashlee H. Rowe
- Department of Biology, University of Oklahoma, Norman, OK, United States
- Graduate Program in Cellular and Behavioral Neurobiology, University of Oklahoma, Norman, OK, United States
- *Correspondence: Ashlee H. Rowe,
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7
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Multitarget nociceptor sensitization by a promiscuous peptide from the venom of the King Baboon spider. Proc Natl Acad Sci U S A 2022; 119:2110932119. [PMID: 35074873 PMCID: PMC8812547 DOI: 10.1073/pnas.2110932119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 12/15/2022] Open
Abstract
The King Baboon spider, Pelinobius muticus, is a burrowing African tarantula. Its impressive size and appealing coloration are tempered by reports describing severe localized pain, swelling, itchiness, and muscle cramping after accidental envenomation. Hyperalgesia is the most prominent symptom after bites from P. muticus, but the molecular basis by which the venom induces pain is unknown. Proteotranscriptomic analysis of P. muticus venom uncovered a cysteine-rich peptide, δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a), that elicited nocifensive behavior when injected into mice. In small dorsal root ganglion neurons, synthetic δ/κ-TRTX-Pm1a (sPm1a) induced hyperexcitability by enhancing tetrodotoxin-resistant sodium currents, impairing repolarization and lowering the threshold of action potential firing, consistent with the severe pain associated with envenomation. The molecular mechanism of nociceptor sensitization by sPm1a involves multimodal actions over several ion channel targets, including NaV1.8, KV2.1, and tetrodotoxin-sensitive NaV channels. The promiscuous targeting of peptides like δ/κ-TRTX-Pm1a may be an evolutionary adaptation in pain-inducing defensive venoms.
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Nakamura M, Jang IS. Propranolol modulation of tetrodotoxin-resistant Na + channels in dural afferent neurons. Eur J Pharmacol 2021; 910:174449. [PMID: 34454925 DOI: 10.1016/j.ejphar.2021.174449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022]
Abstract
Propranolol, a representative adrenergic β-receptor antagonist, is widely used to prevent migraine attacks. Although propranolol is well known to inhibit tetrodotoxin-resistant (TTX-R) Na+ channels in cardiac myocytes, it is unclear whether the drug modulates these channels expressed in dural afferent neurons. In this study, we examined the effects of propranolol on TTX-R Na+ channels in medium-sized dural afferent neurons identified by the fluorescent dye DiI. The TTX-R Na+ currents (INa) were recorded from acutely isolated DiI-positive neurons using a whole-cell patch clamp technique under voltage-clamp conditions. Propranolol inhibited the noninactivating steady-state component more potently than the peak component of transient TTX-R INa. Propranolol also potently inhibited the slow voltage ramp-induced TTX-R INa in a concentration-dependent manner, suggesting that it preferentially inhibited the noninactivating or persistent INa in DiI-positive neurons. Propranolol had little effect on voltage dependence, but it increased the extent of the use-dependent inhibition of TTX-R Na+ channels. Propranolol also accelerated the onset of inactivation and retarded recovery from inactivation in these channels. Under current-clamp conditions, propranolol decreased the number of action potentials elicited by depolarizing current stimuli. In conclusion, the propranolol-mediated preferential inhibition of persistent INa and modulation of the inactivation kinetics of TTX-R Na+ channels might represent additional mechanisms for migraine prophylaxis.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea.
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An Index Combining Lost and Remaining Nerve Fibers Correlates with Pain Hypersensitivity in Mice. Cells 2020; 9:cells9112414. [PMID: 33158176 PMCID: PMC7694241 DOI: 10.3390/cells9112414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/01/2020] [Accepted: 11/02/2020] [Indexed: 11/17/2022] Open
Abstract
Multiple peripheral nerves are known to degenerate after nerve compression injury but the correlation between the extent of nerve alteration and pain severity remains unclear. Here, we used intravital two-photon fluorescence microscopy to longitudinally observe changes in cutaneous fibers in the hind paw of Nav1.8-Cre-tdTomato mice after chronic constriction injury (CCI). Results showed that the CCI led to variable loss of the skin nerve plexus and intraepidermal nerve fibers. The timing of Nav1.8 nerve fiber loss correlated with the development of mechanical hypersensitivity. We compared a scoring approach that assessed whole-paw nerve degeneration with an index that quantified changes in the nerve plexus and terminals in multiple small regions of interest (ROI) from intravital images of the third and fifth toe tips. We found that the number of surviving nerve fibers was not linearly correlated with mechanical hypersensitivity. On the contrary, at 14 days after CCI, the moderately injured mice showed greater mechanical hypersensitivity than the mildly or severely injured mice. This indicates that both surviving and injured nerves are required for evoked neuropathic pain. In addition, these two methods may have the estimative effect as diagnostic and prognostic biomarkers for the assessment of neuropathic pain.
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van Gendt MJ, Siebrecht M, Briaire JJ, Bohte SM, Frijns JHM. Short and long-term adaptation in the auditory nerve stimulated with high-rate electrical pulse trains are better described by a power law. Hear Res 2020; 398:108090. [PMID: 33070033 DOI: 10.1016/j.heares.2020.108090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/02/2020] [Accepted: 09/22/2020] [Indexed: 01/18/2023]
Abstract
Despite the introduction of many new sound-coding strategies speech perception outcomes in cochlear implant listeners have leveled off. Computer models may help speed up the evaluation of new sound-coding strategies, but most existing models of auditory nerve responses to electrical stimulation include limited temporal detail, as the effects of longer stimulation, such as adaptation, are not well-studied. Measured neural responses to stimulation with both short (400 ms) and long (10 min) duration high-rate (5kpps) pulse trains were compared in terms of spike rate and vector strength (VS) with model outcomes obtained with different forms of adaptation. A previously published model combining biophysical and phenomenological approaches was adjusted with adaptation modeled as a single decaying exponent, multiple exponents and a power law. For long duration data, power law adaptation by far outperforms the single exponent model, especially when it is optimized per fiber. For short duration data, all tested models performed comparably well, with slightly better performance of the single exponent model for VS and of the power law model for the spike rates. The power law parameter sets obtained when fitted to the long duration data also yielded adequate predictions for short duration stimulation, and vice versa. The power law function can be approximated with multiple exponents, which is physiologically more viable. The number of required exponents depends on the duration of simulation; the 400 ms data was well-replicated by two exponents (23 and 212 ms), whereas the 10-minute data required at least seven exponents (ranging from 4 ms to 600 s). Adaptation of the auditory nerve to high-rate electrical stimulation can best be described by a power-law or a sum of exponents. This gives an adequate fit for both short and long duration stimuli, such as CI speech segments.
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Affiliation(s)
- M J van Gendt
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands.
| | - M Siebrecht
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
| | - J J Briaire
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
| | - S M Bohte
- CWI, Center for Mathematics and Informatics, Amsterdam, The Netherlands
| | - J H M Frijns
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
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11
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Kumar R, Geron M, Hazan A, Priel A. Endogenous and Exogenous Vanilloids Evoke Disparate TRPV1 Activation to Produce Distinct Neuronal Responses. Front Pharmacol 2020; 11:903. [PMID: 32595512 PMCID: PMC7303340 DOI: 10.3389/fphar.2020.00903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/02/2020] [Indexed: 12/19/2022] Open
Abstract
Neuronal signals are processed along the nociceptive pathway to convey discriminative information, which would manifest in the produced pain sensation. The transient receptor potential vanilloid 1 (TRPV1), an important signaling complex in nociceptors termini, is activated by different noxious stimuli that underlie distinct pain sensations. For example, while endovanilloids are associated with inflammatory pain and hypersensitivity through TRPV1 activation, the exovanilloid toxin, capsaicin, evokes an acute pain by activating this channel. Differences in the TRPV1 activation profile evoked by exogenous and endogenous vanilloids were suggested to underlie this disparity in pain sensations. However, the cellular processes that lead to these differences in pain sensation mediated by the same channel are not fully understood. Here, we sought to describe the neuronal response of TRPV1-expressing nociceptors to exo-and endovanilloids. To this end, we performed current-clamp recordings in rat trigeminal neurons exposed to either capsaicin or intracellular endovanilloids produced downstream of the bradykinin receptor BK2. Our results show that lipoxygenase metabolites generate persistent TRPV1-dependent action potential firing while capsaicin evokes robust depolarization and high-frequency firing that is quickly terminated by depolarization block. Additionally, we found that a weak TRPV1 activation prolongs action potential firing. Overall, our results indicate different firing patterns evoked by inflammatory mediators and capsaicin via TRPV1 that correlate with the respective subsequent pain sensation. These findings also suggest that differences in neuronal activation stem from the variable degree of TRPV1 activation they produce.
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Affiliation(s)
- Rakesh Kumar
- Institute for Drug Research (IDR), School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Matan Geron
- Institute for Drug Research (IDR), School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Adina Hazan
- Institute for Drug Research (IDR), School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Avi Priel
- Institute for Drug Research (IDR), School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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12
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Hart WL, Richardson RT, Kameneva T, Thompson AC, Wise AK, Fallon JB, Stoddart PR, Needham K. Combined optogenetic and electrical stimulation of auditory neurons increases effective stimulation frequency-an in vitro study. J Neural Eng 2020; 17:016069. [PMID: 31923907 DOI: 10.1088/1741-2552/ab6a68] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE The performance of neuroprostheses, including cochlear and retinal implants, is currently constrained by the spatial resolution of electrical stimulation. Optogenetics has improved the spatial control of neurons in vivo but lacks the fast-temporal dynamics required for auditory and retinal signalling. The objective of this study is to demonstrate that combining optical and electrical stimulation in vitro could address some of the limitations associated with each of the stimulus modes when used independently. APPROACH The response of murine auditory neurons expressing ChR2-H134 to combined optical and electrical stimulation was characterised using whole cell patch clamp electrophysiology. MAIN RESULTS Optogenetic costimulation produces a three-fold increase in peak firing rate compared to optical stimulation alone and allows spikes to be evoked by combined subthreshold optical and electrical inputs. Subthreshold optical depolarisation also facilitated spiking in auditory neurons for periods of up to 30 ms without evidence of wide-scale Na+ inactivation. SIGNIFICANCE These findings may contribute to the development of spatially and temporally selective optogenetic-based neuroprosthetics and complement recent developments in 'fast opsins'.
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Affiliation(s)
- William L Hart
- ARC Training Centre in Biodevices, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
| | - Rachael T Richardson
- The Bionics Institute, East Melbourne, VIC 3002, Australia
- Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, VIC 3002, Australia
| | - Tatiana Kameneva
- Swinburne University of Technology, Hawthorn VIC 3122, Australia
| | | | - Andrew K Wise
- The Bionics Institute, East Melbourne, VIC 3002, Australia
- Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, VIC 3002, Australia
| | - James B Fallon
- The Bionics Institute, East Melbourne, VIC 3002, Australia
- Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, VIC 3002, Australia
| | - Paul R Stoddart
- ARC Training Centre in Biodevices, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
| | - Karina Needham
- Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia
- Author to whom any correspondence should be addressed
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13
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Ross GR, Rizvi F, Emelyanova L, Tajik AJ, Jahangir A. Prolonged post-differentiation culture influences the expression and biophysics of Na + and Ca 2+ channels in induced pluripotent stem cell-derived ventricular-like cardiomyocytes. Cell Tissue Res 2019; 378:59-66. [PMID: 31041505 DOI: 10.1007/s00441-019-03030-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 04/04/2019] [Indexed: 12/18/2022]
Abstract
Several studies have been reported in various domains from induction methods to utilities of somatic cell pluripotent reprogramming. However, one of the major struggles facing the research field of induced pluripotent stem cell (iPSC)-derived target cells is the lack of consistency in observations. This could be due to variety of reasons including varied culture periods post-differentiation. The cardiomyocytes (CMs) derived from iPSCs are commonly studied and proposed to be utilized in the comprehensive in vitro proarrhythmia initiative for drug safety screening. As the influence of varied culture periods on the electrophysiological properties of iPSC-CMs is not clearly known, using whole-cell patch clamp technique, we compared two groups of differentiated ventricular-like iPSC-CMs that are cultured for 10 to 15 days (D10-15) and more than 30 days (≥ D30) both under current and voltage clamps. The prolonged culture imparts increased excitability with high-frequency spontaneous action potentials, robust increase in the magnitude of peak Na+ current density, relatively shallow inactivation kinetics of Na+ channels, faster recovery from inactivation, and augmented Ca2+ current density. Quantitative real-time PCR studies of α-subunit transcripts showed enhanced mRNA expression of SCN1A, SCN5A Na+ channel subtypes, and CACNA1C, CACNA1G, and CACNA1I Ca2+ channel subtypes, in ≥ D30 group. Conclusively, the prolonged culture of differentiated iPSC-CMs affects the excitability, single-cell electrophysiological properties, and ion channel expressions. Therefore, following standard periods of culture across research studies while utilizing ventricular-like iPSC-CMs for in vitro health/disease modeling to study cellular functional mechanisms or test high-throughput drugs' efficacy and toxicity becomes crucial.
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Affiliation(s)
- Gracious R Ross
- Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, 2900 W Oklahoma Ave, Milwaukee, WI, 53215, USA.
| | - Farhan Rizvi
- Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, 2900 W Oklahoma Ave, Milwaukee, WI, 53215, USA
| | - Larisa Emelyanova
- Center for Integrative Research on Cardiovascular Aging, Aurora Research Institute, Aurora Health Care, 2900 W Oklahoma Ave, Milwaukee, WI, 53215, USA
| | - A Jamil Tajik
- Aurora Cardiovascular Services, Aurora Sinai/St. Luke's Medical Centers, Milwaukee, WI, USA
| | - Arshad Jahangir
- Aurora Cardiovascular Services, Aurora Sinai/St. Luke's Medical Centers, Milwaukee, WI, USA
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14
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Bennett DL, Clark AJ, Huang J, Waxman SG, Dib-Hajj SD. The Role of Voltage-Gated Sodium Channels in Pain Signaling. Physiol Rev 2019; 99:1079-1151. [DOI: 10.1152/physrev.00052.2017] [Citation(s) in RCA: 256] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute pain signaling has a key protective role and is highly evolutionarily conserved. Chronic pain, however, is maladaptive, occurring as a consequence of injury and disease, and is associated with sensitization of the somatosensory nervous system. Primary sensory neurons are involved in both of these processes, and the recent advances in understanding sensory transduction and human genetics are the focus of this review. Voltage-gated sodium channels (VGSCs) are important determinants of sensory neuron excitability: they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and neurotransmitter release from sensory neuron terminals. Nav1.1, Nav1.6, Nav1.7, Nav1.8, and Nav1.9 are all expressed by adult sensory neurons. The biophysical characteristics of these channels, as well as their unique expression patterns within subtypes of sensory neurons, define their functional role in pain signaling. Changes in the expression of VGSCs, as well as posttranslational modifications, contribute to the sensitization of sensory neurons in chronic pain states. Furthermore, gene variants in Nav1.7, Nav1.8, and Nav1.9 have now been linked to human Mendelian pain disorders and more recently to common pain disorders such as small-fiber neuropathy. Chronic pain affects one in five of the general population. Given the poor efficacy of current analgesics, the selective expression of particular VGSCs in sensory neurons makes these attractive targets for drug discovery. The increasing availability of gene sequencing, combined with structural modeling and electrophysiological analysis of gene variants, also provides the opportunity to better target existing therapies in a personalized manner.
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Affiliation(s)
- David L. Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Alex J. Clark
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Jianying Huang
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Stephen G. Waxman
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Sulayman D. Dib-Hajj
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
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15
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Goldstein RH, Barkai O, Íñigo-Portugués A, Katz B, Lev S, Binshtok AM. Location and Plasticity of the Sodium Spike Initiation Zone in Nociceptive Terminals In Vivo. Neuron 2019; 102:801-812.e5. [PMID: 30926280 DOI: 10.1016/j.neuron.2019.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 01/15/2019] [Accepted: 03/01/2019] [Indexed: 11/18/2022]
Abstract
Nociceptive terminals possess the elements for detecting, transmitting, and modulating noxious signals, thus being pivotal for pain sensation. Despite this, a functional description of the transduction process by the terminals, in physiological conditions, has not been fully achieved. Here, we studied how nociceptive terminals in vivo convert noxious stimuli into propagating signals. By monitoring noxious-stimulus-induced Ca2+ dynamics from mouse corneal terminals, we found that initiation of Na+ channel (Nav)-dependent propagating signals takes place away from the terminal and that the starting point for Nav-mediated propagation depends on Nav functional availability. Acute treatment with the proinflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) resulted in a shift of the location of Nav involvement toward the terminal, thus increasing nociceptive excitability. Moreover, a shift of Nav involvement toward the terminal occurs in corneal hyperalgesia resulting from acute photokeratitis. This dynamic change in the location of Nav-mediated propagation initiation could underlie pathological pain hypersensitivity.
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Affiliation(s)
- Robert H Goldstein
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Almudena Íñigo-Portugués
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, 03550 San Juan de Alicante, Spain
| | - Ben Katz
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel.
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16
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Coates MD, Vrana KE, Ruiz-Velasco V. The influence of voltage-gated sodium channels on human gastrointestinal nociception. Neurogastroenterol Motil 2019; 31:e13460. [PMID: 30216585 DOI: 10.1111/nmo.13460] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 08/01/2018] [Accepted: 08/07/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND Abdominal pain is a frequent and persistent problem in the most common gastrointestinal disorders, including irritable bowel syndrome and inflammatory bowel disease. Pain adversely impacts quality of life, incurs significant healthcare expenditures, and remains a challenging issue to manage with few safe therapeutic options currently available. It is imperative that new methods are developed for identifying and treating this symptom. A variety of peripherally active neuroendocrine signaling elements have the capability to influence gastrointestinal pain perception. A large and growing body of evidence suggests that voltage-gated sodium channels (VGSCs) play a critical role in the development and modulation of nociceptive signaling associated with the gut. Several VGSC isoforms demonstrate significant promise as potential targets for improved diagnosis and treatment of gut-based disorders associated with hyper- and hyposensitivity to abdominal pain. PURPOSE In this article, we critically review key investigations that have evaluated the potential role that VGSCs play in visceral nociception and discuss recent advances related to this topic. Specifically, we discuss the following: (a) what is known about the structure and basic function of VGSCs, (b) the role that each VGSC plays in gut nociception, particularly as it relates to human physiology, and (c) potential diagnostic and therapeutic uses of VGSCs to manage disorders associated with chronic abdominal pain.
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Affiliation(s)
- Matthew D Coates
- Division of Gastroenterology & Hepatology, Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania
| | - Kent E Vrana
- Department of Pharmacology, Penn State University College of Medicine, Hershey, Pennsylvania
| | - Victor Ruiz-Velasco
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Hershey, Pennsylvania
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17
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Zhang XL, Cao XY, Lai RC, Xie MX, Zeng WA. Puerarin Relieves Paclitaxel-Induced Neuropathic Pain: The Role of Na v1.8 β1 Subunit of Sensory Neurons. Front Pharmacol 2019; 9:1510. [PMID: 30666203 PMCID: PMC6330330 DOI: 10.3389/fphar.2018.01510] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 12/10/2018] [Indexed: 12/18/2022] Open
Abstract
Currently there is no effective treatment available for clinical patients suffering from neuropathic pain induced by chemotherapy paclitaxel. Puerarin is a major isoflavonoid extracted from the Chinese medical herb kudzu root, which has been used for treatment of cardiovascular disorders and brain injury. Here, we found that puerarin dose-dependently alleviated paclitaxel-induced neuropathic pain. At the same time, puerarin preferentially reduced the excitability and blocked the voltage-gated sodium (Nav) channels of dorsal root ganglion (DRG) neurons from paclitaxel-induced neuropathic pain rats. Furthermore, puerarin was a more potent blocker of tetrodotoxin-resistant (TTX-R) Nav channels than of tetrodotoxin-sensitive (TTX-S) Nav channels in chronic pain rats’ DRG neurons. In addition, puerarin had a stronger blocking effect on Nav1.8 channels in DRG neurons of neuropathic pain rats and β1 subunit siRNA can abolish this selective blocking effect on Nav1.8. Together, these results suggested that puerarin may preferentially block β1 subunit of Nav1.8 in sensory neurons contributed to its anti-paclitaxel induced neuropathic pain effect.
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Affiliation(s)
- Xiao-Long Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Anesthesiology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xian-Ying Cao
- College of Food Science and Technology, Hainan University, Haikou, China.,State Key Laboratory of Marine Resources Utilization in South China Sea, Hainan University, Haikou, China
| | - Ren-Chun Lai
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Anesthesiology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Man-Xiu Xie
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Anesthesiology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Wei-An Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Anesthesiology, Sun Yat-sen University Cancer Center, Guangzhou, China
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18
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Kang IS, Cho JH, Lee MG, Jang IS. Modulation of tetrodotoxin-resistant Na + channels by amitriptyline in dural afferent neurons. Eur J Pharmacol 2018; 838:69-77. [PMID: 30194938 DOI: 10.1016/j.ejphar.2018.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 10/28/2022]
Abstract
Migraine is characterized by recurrent and disabling headaches; therefore, several drugs have been widely prescribed to prevent acute migraine attacks. Amitriptyline, a tricyclic antidepressant, is among the most commonly administered. It is poorly known, however, whether amitriptyline modulates the excitability of dural afferent neurons that transmit pain signals from the dura mater. In this study, the effects of amitriptyline on tetrodotoxin-resistant (TTX-R) Na+ channels were examined in acutely isolated rat dural afferent neurons, which were identified by the fluorescent dye DiI. The TTX-R Na+ currents (INa) were recorded from medium-sized DiI-positive neurons using a whole-cell patch clamp technique. Amitriptyline (3 μM) slightly reduced the peak component of transient INa and induced a marked decrease in the steady-state component of transient TTX-R INa, as well as in the slow ramp-induced TTX-R INa. Our findings suggest that amitriptyline specifically inhibits persistent Na+ currents mediated by TTX-R Na+ channels. While amitriptyline had minor effects on voltage-activation/inactivation, it increased the extent of the use-dependent inhibition of TTX-R Na+ channels. Amitriptyline also affected the inactivation kinetics of TTX-R Na+ channels by significantly accelerating the inactivation of TTX-R Na+ channels and slowing the subsequent recovery. Amitriptyline decreased the number of action potentials by increasing the threshold for their generation. In conclusion, the amitriptyline-mediated diverse modulation of TTX-R Na+ channels would be, at least in part, responsible for its prophylactic efficacy for migraine attacks.
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Affiliation(s)
- In-Sik Kang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Jin-Hwa Cho
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Maan-Gee Lee
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu 41405, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea.
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19
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Kim DH, Choi JS. Differential use-dependent inactivation of Nav1.8 in the subpopulation of cultured dorsal root ganglion. Mol Cell Toxicol 2018. [DOI: 10.1007/s13273-018-0045-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Haesemeyer M, Robson DN, Li JM, Schier AF, Engert F. A Brain-wide Circuit Model of Heat-Evoked Swimming Behavior in Larval Zebrafish. Neuron 2018; 98:817-831.e6. [PMID: 29731253 PMCID: PMC5985529 DOI: 10.1016/j.neuron.2018.04.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 03/01/2018] [Accepted: 04/10/2018] [Indexed: 11/20/2022]
Abstract
Thermosensation provides crucial information, but how temperature representation is transformed from sensation to behavior is poorly understood. Here, we report a preparation that allows control of heat delivery to zebrafish larvae while monitoring motor output and imaging whole-brain calcium signals, thereby uncovering algorithmic and computational rules that couple dynamics of heat modulation, neural activity and swimming behavior. This approach identifies a critical step in the transformation of temperature representation between the sensory trigeminal ganglia and the hindbrain: A simple sustained trigeminal stimulus representation is transformed into a representation of absolute temperature as well as temperature changes in the hindbrain that explains the observed motor output. An activity constrained dynamic circuit model captures the most prominent aspects of these sensori-motor transformations and predicts both behavior and neural activity in response to novel heat stimuli. These findings provide the first algorithmic description of heat processing from sensory input to behavioral output.
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Affiliation(s)
- Martin Haesemeyer
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Drew N Robson
- The Rowland Institute at Harvard, Cambridge, MA 02142, USA
| | - Jennifer M Li
- The Rowland Institute at Harvard, Cambridge, MA 02142, USA
| | - Alexander F Schier
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Biozentrum, University of Basel, 4056 Basel, Switzerland.
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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21
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Zhou X, Zhang Y, Tang D, Liang S, Chen P, Tang C, Liu Z. A Chimeric NaV1.8 Channel Expression System Based on HEK293T Cell Line. Front Pharmacol 2018; 9:337. [PMID: 29686617 PMCID: PMC5900924 DOI: 10.3389/fphar.2018.00337] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/22/2018] [Indexed: 11/13/2022] Open
Abstract
Among the nine voltage-gated sodium channel (NaV) subtypes, NaV1.8 is an attractive therapeutic target for pain. The heterologous expression of recombinant NaV1.8 currents is of particular importance for its electrophysiological and pharmacological studies. However, NaV1.8 expresses no or low-level functional currents when transiently transfected into non-neuronal cell lines. The present study aims to explore the molecular determinants limiting its functional expression and accordingly establish a functional NaV1.8 expression system. We conducted screening analysis of the NaV1.8 intracellular loops by constructing NaV chimeric channels and confirmed that the NaV1.8 C-terminus was the only limiting factor. Replacing this sequence with that of NaV1.4, NaV1.5, or NaV1.7 constructed functional channels (NaV1.8/1.4L5, NaV1.8/1.5L5, and NaV1.8/1.7L5, respectively), which expressed high-level NaV1.8-like currents in HEK293T cells. The chimeric channel NaV1.8/1.7L5 displayed much faster inactivation of its macroscopic currents than NaV1.8/1.4L5 and NaV1.8/1.5L5, and it was the most similar to wild-type NaV1.8 expressed in ND7/23 cells. Its currents were very stable during repetitive depolarizations, while its repriming kinetic was different from wild-type NaV1.8. Most importantly, NaV1.8/1.7L5 pharmacologically resembled wild-type NaV1.8 as revealed by testing their susceptibility to two NaV1.8 selective antagonists, APETx-2 and MrVIB. NaV chimeras study showed that at least the domain 2 and domain 4 of NaV1.8 were involved in binding with APETx-2. Our study provided new insights into the function of NaV1.8 intracellular loops, as well as a reliable and convenient expression system which could be useful in NaV1.8 studies.
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Affiliation(s)
| | | | | | | | | | - Cheng Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
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22
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Abstract
Abstract
Painful stimuli are detected by specialized neurons, nociceptors, and are translated into action potentials, that are conducted along afferent pathways into the central nervous system, where they are conceived as pain. Voltage-gated sodium channels (NaV channels) are of paramount importance for nociceptor function, as they are responsible for the generation of action potentials and for their directed propagation. The exceptional role of sodium channel subtypes NaV1.7, NaV1.8 and NaV1.9 in the transmission of nociceptive signals has been emphasized by a variety of studies that associated genetically-induced malfunction of these channels with various pain diseases. In the following, structure and function of subtypes NaV1.7, NaV1.8 und NaV1.9 are briefly reviewed, associated pain diseases are introduced and current and future NaV-based strategies for the treatment of pain are discussed.
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Affiliation(s)
- Carla Nau
- Department of Anesthesiology and Intensive Care , University Medical Center Schleswig-Holstein, Campus Luebeck , Ratzeburger Allee 160, 23538 Luebeck , Germany , Phone: +49 451 50040701, Fax: +49 451 50040704
| | - Enrico Leipold
- Center for Molecular Biomedicine , Department of Biophysics, Friedrich Schiller University Jena , Hans-Knoell-St. 2, 07745 Jena , Germany , Phone: +49 3641 9395654, Fax: +49 3641 9395652
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23
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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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24
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Barkai O, Goldstein RH, Caspi Y, Katz B, Lev S, Binshtok AM. The Role of Kv7/M Potassium Channels in Controlling Ectopic Firing in Nociceptors. Front Mol Neurosci 2017; 10:181. [PMID: 28659757 PMCID: PMC5468463 DOI: 10.3389/fnmol.2017.00181] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/24/2017] [Indexed: 11/13/2022] Open
Abstract
Peripheral nociceptive neurons encode and convey injury-inducing stimuli toward the central nervous system. In normal conditions, tight control of nociceptive resting potential prevents their spontaneous activation. However, in many pathological conditions the control of membrane potential is disrupted, leading to ectopic, stimulus-unrelated firing of nociceptive neurons, which is correlated to spontaneous pain. We have investigated the role of KV7/M channels in stabilizing membrane potential and impeding spontaneous firing of nociceptive neurons. These channels generate low voltage-activating, noninactivating M-type K+ currents (M-current, IM ), which control neuronal excitability. Using perforated-patch recordings from cultured, rat nociceptor-like dorsal root ganglion neurons, we show that inhibition of M-current leads to depolarization of nociceptive neurons and generation of repetitive firing. To assess to what extent the M-current, acting at the nociceptive terminals, is able to stabilize terminals' membrane potential, thus preventing their ectopic activation, in normal and pathological conditions, we built a multi-compartment computational model of a pseudo-unipolar unmyelinated nociceptive neuron with a realistic terminal tree. The modeled terminal tree was based on the in vivo structure of nociceptive peripheral terminal, which we assessed by in vivo multiphoton imaging of GFP-expressing nociceptive neuronal terminals innervating mice hind paw. By modifying the conductance of the KV7/M channels at the modeled terminal tree (terminal gKV7/M) we have found that 40% of the terminal gKV7/M conductance is sufficient to prevent spontaneous firing, while ~75% of terminal gKV7/M is sufficient to inhibit stimulus induced activation of nociceptive neurons. Moreover, we showed that terminal M-current reduces susceptibility of nociceptive neurons to a small fluctuations of membrane potentials. Furthermore, we simulated how the interaction between terminal persistent sodium current and M-current affects the excitability of the neurons. We demonstrated that terminal M-current in nociceptive neurons impeded spontaneous firing even when terminal Na(V)1.9 channels conductance was substantially increased. On the other hand, when terminal gKV7/M was decreased, nociceptive neurons fire spontaneously after slight increase in terminal Na(V)1.9 conductance. Our results emphasize the pivotal role of M-current in stabilizing membrane potential and hereby in controlling nociceptive spontaneous firing, in normal and pathological conditions.
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Affiliation(s)
- Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Robert H Goldstein
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Yaki Caspi
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Ben Katz
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
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25
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Sparling BA, Yi S, Able J, Bregman H, DiMauro EF, Foti RS, Gao H, Guzman-Perez A, Huang H, Jarosh M, Kornecook T, Ligutti J, Milgram BC, Moyer BD, Youngblood B, Yu VL, Weiss MM. Discovery and hit-to-lead evaluation of piperazine amides as selective, state-dependent Na V1.7 inhibitors. MEDCHEMCOMM 2017; 8:744-754. [PMID: 30108793 PMCID: PMC6072352 DOI: 10.1039/c6md00578k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/30/2016] [Indexed: 11/21/2022]
Abstract
NaV1.7 is a particularly compelling target for the treatment of pain. Herein, we report the discovery and evaluation of a series of piperazine amides that exhibit state-dependent inhibition of NaV1.7. After demonstrating significant pharmacodynamic activity with early lead compound 14 in a NaV1.7-dependent behavioural mouse model, we systematically established SAR trends throughout each sector of the scaffold. The information gleaned from this modular analysis was then applied additively to quickly access analogues that encompass an optimal balance of properties, including NaV1.7 potency, selectivity over NaV1.5, aqueous solubility, and microsomal stability.
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Affiliation(s)
- Brian A Sparling
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - S Yi
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - J Able
- Department of Neuroscience , Amgen Inc. , One Amgen Center Drive , Thousand Oaks , CA 91320 , USA
| | - H Bregman
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - Erin F DiMauro
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - R S Foti
- Department of Pharmacokinetics and Drug Metabolism , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA
| | - H Gao
- Department of Molecular Engineering, Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA
| | - A Guzman-Perez
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - H Huang
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - M Jarosh
- Department of Neuroscience , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA
| | - T Kornecook
- Department of Neuroscience , Amgen Inc. , One Amgen Center Drive , Thousand Oaks , CA 91320 , USA
| | - J Ligutti
- Department of Neuroscience , Amgen Inc. , One Amgen Center Drive , Thousand Oaks , CA 91320 , USA
| | - B C Milgram
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
| | - B D Moyer
- Department of Neuroscience , Amgen Inc. , One Amgen Center Drive , Thousand Oaks , CA 91320 , USA
| | - B Youngblood
- Department of Neuroscience , Amgen Inc. , One Amgen Center Drive , Thousand Oaks , CA 91320 , USA
| | - V L Yu
- Department of Neuroscience , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA
| | - M M Weiss
- Department of Medicinal Chemistry , Amgen Inc. , 360 Binney Street , Cambridge , MA 02142 , USA .
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Abstract
Purpose of Review Pitt Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder that results from mutations of the clinically pleiotropic Transcription Factor 4 (TCF4) gene. Mutations in the genomic locus of TCF4 on chromosome 18 have been linked to multiple disorders including 18q syndrome, schizophrenia, Fuch's corneal dystrophy, and sclerosing cholangitis. For PTHS, TCF4 mutation or deletion leads to the production of a dominant negative TCF4 protein and/or haploinsufficiency that results in abnormal brain development. The biology of TCF4 has been studied for several years in regards to its role in immune cell differentiation, although its role in neurodevelopment and the mechanisms resulting in the severe symptoms of PTHS are not well studied. Recent Findings Here, we summarize the current understanding of PTHS and recent findings that have begun to describe the biological implications of TCF4 deficiency during brain development and into adulthood. In particular, we focus on recent work that has looked at the role of TCF4 biology within the context of PTHS and highlight the potential for identification of therapeutic targets for PTHS. Summary PTHS research continues to uncover mutations in TCF4 that underlie the genetic cause of this rare disease, and emerging evidence for molecular mechanisms that TCF4 regulates in brain development and neuronal function is contributing to a more complete picture of how pathology arises from this genetic basis, with important implications for the potential of future clinical care.
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Kumar R, Hazan A, Geron M, Steinberg R, Livni L, Matzner H, Priel A. Activation of transient receptor potential vanilloid 1 by lipoxygenase metabolites depends on PKC phosphorylation. FASEB J 2016; 31:1238-1247. [PMID: 27986808 DOI: 10.1096/fj.201601132r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 12/06/2016] [Indexed: 11/11/2022]
Abstract
Peripheral neuronal activation by inflammatory mediators is a multifaceted physiological response that involves a multitude of regulated cellular functions. One key pathway that has been shown to be involved in inflammatory pain is Gq/GPCR, whose activation by inflammatory mediators is followed by the regulated response of the cation channel transient receptor potential vanilloid 1 (TRPV1). However, the mechanism that underlies TRPV1 activation downstream of the Gq/GPCR pathway has yet to be fully defined. In this study, we employ pharmacological and molecular biology tools to dissect this activation mechanism via perforated-patch recordings and calcium imaging of both neurons and a heterologous system. We showed that TRPV1 activity downstream of Gq/GPCR activation only produced a subdued current, which was noticeably different from the robust current that is typical of TRPV1 activation by exogenous stimuli. Moreover, we specifically demonstrated that 2 pathways downstream of Gq/GPCR signaling, namely endovanilloid production by lipoxygenases and channel phosphorylation by PKC, converge on TRPV1 to evoke a tightly regulated response. Of importance, we show that only when both pathways are acting on TRPV1 is the inflammatory-mediated response achieved. We propose that the requirement of multiple signaling events allows subdued TRPV1 activation to evoke regulated neuronal response during inflammation.-Kumar R., Hazan, A., Geron, M., Steinberg, R., Livni, L., Matzner, H., Priel, A. Activation of transient receptor potential vanilloid 1 by lipoxygenase metabolites depends on PKC phosphorylation.
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Affiliation(s)
- Rakesh Kumar
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Adina Hazan
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Matan Geron
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rebbeca Steinberg
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lital Livni
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Henry Matzner
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Avi Priel
- Institute for Drug Research, School of Pharmacy, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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28
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Reduced excitability and impaired nociception in peripheral unmyelinated fibers from Nav1.9-null mice. Pain 2016; 158:58-67. [DOI: 10.1097/j.pain.0000000000000723] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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29
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Kist AM, Sagafos D, Rush AM, Neacsu C, Eberhardt E, Schmidt R, Lunden LK, Ørstavik K, Kaluza L, Meents J, Zhang Z, Carr TH, Salter H, Malinowsky D, Wollberg P, Krupp J, Kleggetveit IP, Schmelz M, Jørum E, Lampert A, Namer B. SCN10A Mutation in a Patient with Erythromelalgia Enhances C-Fiber Activity Dependent Slowing. PLoS One 2016; 11:e0161789. [PMID: 27598514 PMCID: PMC5012686 DOI: 10.1371/journal.pone.0161789] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/11/2016] [Indexed: 11/18/2022] Open
Abstract
Gain-of-function mutations in the tetrodotoxin (TTX) sensitive voltage-gated sodium channel (Nav) Nav1.7 have been identified as a key mechanism underlying chronic pain in inherited erythromelalgia. Mutations in TTX resistant channels, such as Nav1.8 or Nav1.9, were recently connected with inherited chronic pain syndromes. Here, we investigated the effects of the p.M650K mutation in Nav1.8 in a 53 year old patient with erythromelalgia by microneurography and patch-clamp techniques. Recordings of the patient’s peripheral nerve fibers showed increased activity dependent slowing (ADS) in CMi and less spontaneous firing compared to a control group of erythromelalgia patients without Nav mutations. To evaluate the impact of the p.M650K mutation on neuronal firing and channel gating, we performed current and voltage-clamp recordings on transfected sensory neurons (DRGs) and neuroblastoma cells. The p.M650K mutation shifted steady-state fast inactivation of Nav1.8 to more hyperpolarized potentials and did not significantly alter any other tested gating behaviors. The AP half-width was significantly broader and the stimulated action potential firing rate was reduced for M650K transfected DRGs compared to WT. We discuss the potential link between enhanced steady state fast inactivation, broader action potential width and the potential physiological consequences.
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Affiliation(s)
- Andreas M. Kist
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dagrun Sagafos
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | | | - Cristian Neacsu
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Esther Eberhardt
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department of Anesthesiology, Friedrich-Alexander-Universität Erlangen-Nuremberg, Erlangen, Germany
| | - Roland Schmidt
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Lars Kristian Lunden
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Kristin Ørstavik
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Luisa Kaluza
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jannis Meents
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | | | | | | | | | | | | | - Inge Petter Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Martin Schmelz
- Department of Anesthesiology Mannheim, Heidelberg University, Mannheim, Germany
| | - Ellen Jørum
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
- * E-mail: (EJ); (AL); (BN)
| | - Angelika Lampert
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
- * E-mail: (EJ); (AL); (BN)
| | - Barbara Namer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department of Anesthesiology Mannheim, Heidelberg University, Mannheim, Germany
- * E-mail: (EJ); (AL); (BN)
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30
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Hoffmann T, Kistner K, Nassar M, Reeh PW, Weidner C. Use dependence of peripheral nociceptive conduction in the absence of tetrodotoxin-resistant sodium channel subtypes. J Physiol 2016; 594:5529-41. [PMID: 27105013 DOI: 10.1113/jp272082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/11/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This study examines conduction in peripheral nerves and its use dependence in tetrodotoxin-resistant (TTXr) sodium channel (Nav 1.8, Nav 1.9) knockout and wildtype animals. We observed use-dependent decreases of single fibre and compound action potential amplitude in peripheral mouse C-fibres (wildtype). This matches the previously published hypothesis that increased Na/K-pump activity is not the underlying mechanism for use-dependent changes of neural conduction. Knocking out TTXr sodium channels influences use-dependent changes of conductive properties (action potential amplitude, latency, conduction safety) in the order Nav 1.8 KO > Nav 1.9KO > wildtype. This is most likely explained by different subsets of presumably (relatively) Nav 1.7-rich conducting fibres in knockout animals as compared to wildtypes, in combination with reduced per-pulse sodium influx. ABSTRACT Use dependency of peripheral nerves, especially of nociceptors, correlates with receptive properties. Slow inactivation of voltage-gated sodium channels has been discussed to be the underlying mechanism - pointing to a receptive class-related difference of sodium channel equipment. Using electrophysiological recordings of single unmyelinated cutaneous fibres and their compound action potential (AP), we evaluated use-dependent changes in mouse peripheral nerves, and the contribution of the tetrodotoxin-resistant (TTXr) sodium channels Nav 1.8 and Nav 1.9 to these changes. Nerve fibres were electrically stimulated using single or double pulses at 2 Hz. Use-dependent changes of latency, AP amplitude, and duration as well as the fibres' ability to follow the stimulus were evaluated. AP amplitudes substantially diminished in used fibres from C57BL/6 but increased in Nav 1.8 knockout (KO) mice, with Nav 1.9 KO in between. Activity-induced latency slowing was in contrast the most pronounced in Nav 1.8 KOs and the least in wildtype mice. The genotype was also predictive of how long fibres could follow the double pulsed stimulus with wildtype fibres blocking first and Nav 1.8 KO fibres enduring the longest. In contrast, changes in spike duration were less pronounced and displayed no significant tendency. Thus, all major measures of peripheral nerve accommodation (amplitude, latency and durability) depended on genotype. All use-dependent changes appeared in the order NaV 1.8 KO > NaV 1.9 KO > wildtype, which is most likely explained by the relative contribution of Nav 1.7 varying in the same order and the amounts of per-pulse sodium influx expected in the opposite order.
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Affiliation(s)
- Tal Hoffmann
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany.
| | - Katrin Kistner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | | | - Peter W Reeh
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Christian Weidner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
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31
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Rannals MD, Hamersky GR, Page SC, Campbell MN, Briley A, Gallo RA, Phan BN, Hyde TM, Kleinman JE, Shin JH, Jaffe AE, Weinberger DR, Maher BJ. Psychiatric Risk Gene Transcription Factor 4 Regulates Intrinsic Excitability of Prefrontal Neurons via Repression of SCN10a and KCNQ1. Neuron 2016; 90:43-55. [PMID: 26971948 PMCID: PMC4824652 DOI: 10.1016/j.neuron.2016.02.021] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 10/09/2015] [Accepted: 02/12/2016] [Indexed: 01/28/2023]
Abstract
Transcription Factor 4 (TCF4) is a clinically pleiotropic gene associated with schizophrenia and Pitt-Hopkins syndrome (PTHS). To gain insight about the neurobiology of TCF4, we created an in vivo model of PTHS by suppressing Tcf4 expression in rat prefrontal neurons immediately prior to neurogenesis. This cell-autonomous genetic insult attenuated neuronal spiking by increasing the afterhyperpolarization. At the molecular level, using a novel technique called iTRAP that combined in utero electroporation and translating ribosome affinity purification, we identified increased translation of two ion channel genes, Kcnq1 and Scn10a. These ion channel candidates were validated by pharmacological rescue and molecular phenocopy. Remarkably, similar excitability deficits were observed in prefrontal neurons from a Tcf4(+/tr) mouse model of PTHS. Thus, we identify TCF4 as a regulator of neuronal intrinsic excitability in part by repression of Kcnq1 and Scn10a and suggest that this molecular function may underlie pathophysiology associated with neuropsychiatric disorders.
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Affiliation(s)
- Matthew D Rannals
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Gregory R Hamersky
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Stephanie Cerceo Page
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Morganne N Campbell
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Aaron Briley
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Ryan A Gallo
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - BaDoi N Phan
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Thomas M Hyde
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA; Department of Neurology and the McKusick Nathans Institute of Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Joel E Kleinman
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA; Department of Neurology and the McKusick Nathans Institute of Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Joo Heon Shin
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA
| | - Andrew E Jaffe
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA; Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Daniel R Weinberger
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA; Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA; Department of Neurology and the McKusick Nathans Institute of Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Brady J Maher
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA; Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
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32
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Liu XP, Wooltorton JRA, Gaboyard-Niay S, Yang FC, Lysakowski A, Eatock RA. Sodium channel diversity in the vestibular ganglion: NaV1.5, NaV1.8, and tetrodotoxin-sensitive currents. J Neurophysiol 2016; 115:2536-55. [PMID: 26936982 DOI: 10.1152/jn.00902.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 02/02/2016] [Indexed: 01/02/2023] Open
Abstract
Firing patterns differ between subpopulations of vestibular primary afferent neurons. The role of sodium (NaV) channels in this diversity has not been investigated because NaV currents in rodent vestibular ganglion neurons (VGNs) were reported to be homogeneous, with the voltage dependence and tetrodotoxin (TTX) sensitivity of most neuronal NaV channels. RT-PCR experiments, however, indicated expression of diverse NaV channel subunits in the vestibular ganglion, motivating a closer look. Whole cell recordings from acutely dissociated postnatal VGNs confirmed that nearly all neurons expressed NaV currents that are TTX-sensitive and have activation midpoints between -30 and -40 mV. In addition, however, many VGNs expressed one of two other NaV currents. Some VGNs had a small current with properties consistent with NaV1.5 channels: low TTX sensitivity, sensitivity to divalent cation block, and a relatively negative voltage range, and some VGNs showed NaV1.5-like immunoreactivity. Other VGNs had a current with the properties of NaV1.8 channels: high TTX resistance, slow time course, and a relatively depolarized voltage range. In two NaV1.8 reporter lines, subsets of VGNs were labeled. VGNs with NaV1.8-like TTX-resistant current also differed from other VGNs in the voltage dependence of their TTX-sensitive currents and in the voltage threshold for spiking and action potential shape. Regulated expression of NaV channels in primary afferent neurons is likely to selectively affect firing properties that contribute to the encoding of vestibular stimuli.
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Affiliation(s)
- Xiao-Ping Liu
- Speech and Hearing Bioscience and Technology Program, Harvard-Massachusetts Institute of Technology Health Sciences and Technology Program, Cambridge, Massachusetts; Eaton-Peabody Laboratories, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts
| | | | - Sophie Gaboyard-Niay
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois
| | - Fu-Chia Yang
- Dana-Farber Cancer Institute, Boston, Massachusetts; Department of Neurobiology, Harvard Medical School, Boston, Massachusetts; and
| | - Anna Lysakowski
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois; Department of Otolaryngology-Head and Neck Surgery, University of Illinois at Chicago, Chicago, Illinois
| | - Ruth Anne Eatock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts; Department of Neurobiology, Harvard Medical School, Boston, Massachusetts; and Department of Otolaryngology-Head and Neck Surgery, University of Illinois at Chicago, Chicago, Illinois
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33
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Nakamura M, Jang IS. Indomethacin inhibits tetrodotoxin-resistant Na(+) channels at acidic pH in rat nociceptive neurons. Neuropharmacology 2016; 105:454-462. [PMID: 26898291 DOI: 10.1016/j.neuropharm.2016.02.017] [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: 11/14/2015] [Revised: 02/02/2016] [Accepted: 02/15/2016] [Indexed: 02/06/2023]
Abstract
Non-steroidal anti-inflammatory drugs (NSAIDs) are well-known inhibitors of cyclooxygenases (COXs) and are widely used for the treatment of inflammatory pain; however several NSAIDs display COX-independent analgesic action including the inhibition of voltage-gated Na(+) channels expressed in primary afferent neurons. In the present study, we examined whether NSAIDs modulate tetrodotoxin-resistant (TTX-R) Na(+) channels and if this modulation depends on the extracellular pH. The TTX-R Na(+) currents were recorded from small-sized trigeminal ganglion neurons by using a whole-cell patch clamp technique. Among eight NSAIDs tested in this study, several drugs, including aspirin and ibuprofen, did not affect TTX-R Na(+) channels either at pH 7.4 or at pH 6.0. However, we found that indomethacin, and, to a lesser extent, ibuprofen and naproxen potently inhibited the peak amplitude of TTX-R Na(+) currents at pH 6.0. The indomethacin-induced inhibition of TTX-R Na(+) channels was more potent at depolarized membrane potentials. Indomethacin significantly shifted both the voltage-activation and voltage-inactivation relationships to depolarizing potentials at pH 6.0. Indomethacin accelerated the development of inactivation and retarded the recovery from inactivation of TTX-R Na(+) channels at pH 6.0. Given that indomethacin and several other NSAIDs could further suppress local nociceptive signals by inhibiting TTX-R Na(+) channels at an acidic pH in addition to the classical COX inhibition, these drugs could be particularly useful for the treatment of inflammatory pain.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea.
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34
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Barbosa C, Cummins TR. Unusual Voltage-Gated Sodium Currents as Targets for Pain. CURRENT TOPICS IN MEMBRANES 2016; 78:599-638. [PMID: 27586296 DOI: 10.1016/bs.ctm.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons.
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Affiliation(s)
- C Barbosa
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - T R Cummins
- Indiana University School of Medicine, Indianapolis, IN, United States
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35
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Tigerholm J, Petersson ME, Obreja O, Eberhardt E, Namer B, Weidner C, Lampert A, Carr RW, Schmelz M, Fransén E. C-fiber recovery cycle supernormality depends on ion concentration and ion channel permeability. Biophys J 2016; 108:1057-71. [PMID: 25762318 DOI: 10.1016/j.bpj.2014.12.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/30/2014] [Accepted: 12/17/2014] [Indexed: 12/20/2022] Open
Abstract
Following each action potential, C-fiber nociceptors undergo cyclical changes in excitability, including a period of superexcitability, before recovering their basal excitability state. The increase in superexcitability during this recovery cycle depends upon their immediate firing history of the axon, but also determines the instantaneous firing frequency that encodes pain intensity. To explore the mechanistic underpinnings of the recovery cycle phenomenon a biophysical model of a C-fiber has been developed. The model represents the spatial extent of the axon including its passive properties as well as ion channels and the Na/K-ATPase ion pump. Ionic concentrations were represented inside and outside the membrane. The model was able to replicate the typical transitions in excitability from subnormal to supernormal observed empirically following a conducted action potential. In the model, supernormality depended on the degree of conduction slowing which in turn depends upon the frequency of stimulation, in accordance with experimental findings. In particular, we show that activity-dependent conduction slowing is produced by the accumulation of intraaxonal sodium. We further show that the supernormal phase results from a reduced potassium current Kdr as a result of accumulation of periaxonal potassium in concert with a reduced influx of sodium through Nav1.7 relative to Nav1.8 current. This theoretical prediction was supported by data from an in vitro preparation of small rat dorsal root ganglion somata showing a reduction in the magnitude of tetrodotoxin-sensitive relative to tetrodotoxin -resistant whole cell current. Furthermore, our studies provide support for the role of depolarization in supernormality, as previously suggested, but we suggest that the basic mechanism depends on changes in ionic concentrations inside and outside the axon. The understanding of the mechanisms underlying repetitive discharges in recovery cycles may provide insight into mechanisms of spontaneous activity, which recently has been shown to correlate to a perceived level of pain.
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Affiliation(s)
- Jenny Tigerholm
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Marcus E Petersson
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Otilia Obreja
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Esther Eberhardt
- Institute of Physiology and Pathophysiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Namer
- Department of Anesthesiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Weidner
- Department of Anesthesiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Angelika Lampert
- Institute of Physiology and Pathophysiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Richard W Carr
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Schmelz
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Erik Fransén
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden.
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Kharatmal S, Singh J, Sharma S. Comparative evaluation of in vitro and in vivo high glucose-induced alterations in voltage-gated tetrodotoxin-resistant sodium channel: Effects attenuated by sodium channel blockers. Neuroscience 2015; 305:183-96. [DOI: 10.1016/j.neuroscience.2015.07.085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/24/2015] [Accepted: 07/31/2015] [Indexed: 10/23/2022]
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Differential modulation of Nav1.7 and Nav1.8 channels by antidepressant drugs. Eur J Pharmacol 2015; 764:395-403. [DOI: 10.1016/j.ejphar.2015.06.053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/25/2015] [Accepted: 06/26/2015] [Indexed: 02/03/2023]
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Assessment of TTX-s and TTX-r Action Potential Conduction along Neurites of NGF and GDNF Cultured Porcine DRG Somata. PLoS One 2015; 10:e0139107. [PMID: 26407014 PMCID: PMC4583387 DOI: 10.1371/journal.pone.0139107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/09/2015] [Indexed: 12/19/2022] Open
Abstract
Nine isoforms of voltage-gated sodium channels (NaV) have been characterized and in excitable tissues they are responsible for the initiation and conduction of action potentials. For primary afferent neurons residing in dorsal root ganglia (DRG), individual neurons may express multiple NaV isoforms extending the neuron’s functional capabilities. Since expression of NaV isoforms can be differentially regulated by neurotrophic factors we have examined the functional consequences of exposure to either nerve growth factor (NGF) or glial cell line-derived neurotrophic factor (GDNF) on action potential conduction in outgrowing cultured porcine neurites of DRG neurons. Calcium signals were recorded using the exogenous intensity based calcium indicator Fluo-8®, AM. In 94 neurons, calcium signals were conducted along neurites in response to electrical stimulation of the soma. At an image acquisition rate of 25 Hz it was possible to discern calcium transients in response to individual electrical stimuli. The peak amplitude of electrically-evoked calcium signals was limited by the ability of the neuron to follow the stimulus frequency. The stimulus frequency required to evoke a half-maximal calcium response was approximately 3 Hz at room temperature. In 13 of 14 (93%) NGF-responsive neurites, TTX-r NaV isoforms alone were sufficient to support propagated signals. In contrast, calcium signals mediated by TTX-r NaVs were evident in only 4 of 11 (36%) neurites from somata cultured in GDNF. This establishes a basis for assessing action potential signaling using calcium imaging techniques in individual cultured neurites and suggests that, in the pig, afferent nociceptor classes relying on the functional properties of TTX-r NaV isoforms, such as cold-nociceptors, most probably derive from NGF-responsive DRG neurons.
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Zhu L, McDavid S, Currie KPM. "Slow" Voltage-Dependent Inactivation of CaV2.2 Calcium Channels Is Modulated by the PKC Activator Phorbol 12-Myristate 13-Acetate (PMA). PLoS One 2015. [PMID: 26222492 PMCID: PMC4519294 DOI: 10.1371/journal.pone.0134117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
CaV2.2 (N-type) voltage-gated calcium channels (Ca2+ channels) play key roles in neurons and neuroendocrine cells including the control of cellular excitability, neurotransmitter / hormone secretion, and gene expression. Calcium entry is precisely controlled by channel gating properties including multiple forms of inactivation. “Fast” voltage-dependent inactivation is relatively well-characterized and occurs over the tens-to- hundreds of milliseconds timeframe. Superimposed on this is the molecularly distinct, but poorly understood process of “slow” voltage-dependent inactivation, which develops / recovers over seconds-to-minutes. Protein kinases can modulate “slow” inactivation of sodium channels, but little is known about if/how second messengers control “slow” inactivation of Ca2+ channels. We investigated this using recombinant CaV2.2 channels expressed in HEK293 cells and native CaV2 channels endogenously expressed in adrenal chromaffin cells. The PKC activator phorbol 12-myristate 13-acetate (PMA) dramatically prolonged recovery from “slow” inactivation, but an inactive control (4α-PMA) had no effect. This effect of PMA was prevented by calphostin C, which targets the C1-domain on PKC, but only partially reduced by inhibitors that target the catalytic domain of PKC. The subtype of the channel β-subunit altered the kinetics of inactivation but not the magnitude of slowing produced by PMA. Intracellular GDP-β-S reduced the effect of PMA suggesting a role for G proteins in modulating “slow” inactivation. We postulate that the kinetics of recovery from “slow” inactivation could provide a molecular memory of recent cellular activity and help control CaV2 channel availability, electrical excitability, and neurotransmission in the seconds-to-minutes timeframe.
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Affiliation(s)
- Lei Zhu
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sarah McDavid
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kevin P. M. Currie
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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Fawley JA, Hofmann ME, Largent-Milnes TM, Andresen MC. Temperature differentially facilitates spontaneous but not evoked glutamate release from cranial visceral primary afferents. PLoS One 2015; 10:e0127764. [PMID: 25992717 PMCID: PMC4439140 DOI: 10.1371/journal.pone.0127764] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/20/2015] [Indexed: 11/19/2022] Open
Abstract
Temperature is fundamentally important to all biological functions including synaptic glutamate release. Vagal afferents from the solitary tract (ST) synapse on second order neurons in the nucleus of the solitary tract, and glutamate release at this first central synapse controls autonomic reflex function. Expression of the temperature-sensitive Transient Receptor Potential Vanilloid Type 1 receptor separates ST afferents into C-fibers (TRPV1+) and A-fibers (TRPV1-). Action potential-evoked glutamate release is similar between C- and A-fiber afferents, but TRPV1 expression facilitates a second form of synaptic glutamate release in C-fibers by promoting substantially more spontaneous glutamate release. The influence of temperature on different forms of glutamate release is not well understood. Here we tested how temperature impacts the generation of evoked and spontaneous release of glutamate and its relation to TRPV1 expression. In horizontal brainstem slices of rats, activation of ST primary afferents generated synchronous evoked glutamate release (ST-eEPSCs) at constant latency whose amplitude reflects the probability of evoked glutamate release. The frequency of spontaneous EPSCs in these same neurons measured the probability of spontaneous glutamate release. We measured both forms of glutamate from each neuron during ramp changes in bath temperature of 4-5 °C. Spontaneous glutamate release from TRPV1+ closely tracked with these thermal changes indicating changes in the probability of spontaneous glutamate release. In the same neurons, temperature changed axon conduction registered as latency shifts but ST-eEPSC amplitudes were constant and independent of TRPV1 expression. These data indicate that TRPV1-operated glutamate release is independent of action potential-evoked glutamate release in the same neurons. Together, these support the hypothesis that evoked and spontaneous glutamate release originate from two pools of vesicles that are independently modulated and are distinct processes.
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Affiliation(s)
- Jessica A. Fawley
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
| | - Mackenzie E. Hofmann
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Tally M. Largent-Milnes
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Michael C. Andresen
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
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Sforna L, D'Adamo MC, Servettini I, Guglielmi L, Pessia M, Franciolini F, Catacuzzeno L. Expression and function of a CP339,818-sensitive K⁺ current in a subpopulation of putative nociceptive neurons from adult mouse trigeminal ganglia. J Neurophysiol 2015; 113:2653-65. [PMID: 25652918 PMCID: PMC4416569 DOI: 10.1152/jn.00379.2014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 02/02/2015] [Indexed: 01/15/2023] Open
Abstract
Trigeminal ganglion (TG) neurons are functionally and morphologically heterogeneous, and the molecular basis of this heterogeneity is still not fully understood. Here we describe experiments showing that a subpopulation of neurons expresses a delayed-rectifying K(+) current (IDRK) with a characteristically high (nanomolar) sensitivity to the dihydroquinoline CP339,818 (CP). Although submicromolar CP has previously been shown to selectively block Kv1.3 and Kv1.4 channels, the CP-sensitive IDRK found in TG neurons could not be associated with either of these two K(+) channels. It could neither be associated with Kv2.1 channels homomeric or heteromerically associated with the Kv9.2, Kv9.3, or Kv6.4 subunits, whose block by CP, tested using two-electrode voltage-clamp recordings from Xenopus oocytes, resulted in the low micromolar range, nor to the Kv7 subfamily, given the lack of blocking efficacy of 3 μM XE991. Within the group of multiple-firing neurons considered in this study, the CP-sensitive IDRK was preferentially expressed in a subpopulation showing several nociceptive markers, such as small membrane capacitance, sensitivity to capsaicin, and slow afterhyperpolarization (AHP); in these neurons the CP-sensitive IDRK controls the membrane resting potential, the firing frequency, and the AHP duration. A biophysical study of the CP-sensitive IDRK indicated the presence of two kinetically distinct components: a fast deactivating component having a relatively depolarized steady-state inactivation (IDRKf) and a slow deactivating component with a more hyperpolarized V1/2 for steady-state inactivation (IDRKs).
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Affiliation(s)
- Luigi Sforna
- Dipartimento di Chimica, Biologia e Biotecnologie, Universitá di Perugia, Perugia, Italy; and
| | - Maria Cristina D'Adamo
- Dipartimento di Medicina Sperimentale, Facoltá di Medicina e Chirurgia, Universitá di Perugia, Perugia, Italy
| | - Ilenio Servettini
- Dipartimento di Medicina Sperimentale, Facoltá di Medicina e Chirurgia, Universitá di Perugia, Perugia, Italy
| | - Luca Guglielmi
- Dipartimento di Medicina Sperimentale, Facoltá di Medicina e Chirurgia, Universitá di Perugia, Perugia, Italy
| | - Mauro Pessia
- Dipartimento di Medicina Sperimentale, Facoltá di Medicina e Chirurgia, Universitá di Perugia, Perugia, Italy
| | - Fabio Franciolini
- Dipartimento di Chimica, Biologia e Biotecnologie, Universitá di Perugia, Perugia, Italy; and
| | - Luigi Catacuzzeno
- Dipartimento di Chimica, Biologia e Biotecnologie, Universitá di Perugia, Perugia, Italy; and
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42
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Gudes S, Barkai O, Caspi Y, Katz B, Lev S, Binshtok AM. The role of slow and persistent TTX-resistant sodium currents in acute tumor necrosis factor-α-mediated increase in nociceptors excitability. J Neurophysiol 2015; 113:601-19. [PMID: 25355965 PMCID: PMC4297796 DOI: 10.1152/jn.00652.2014] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/26/2014] [Indexed: 12/12/2022] Open
Abstract
Tetrodotoxin-resistant (TTX-r) sodium channels are key players in determining the input-output properties of peripheral nociceptive neurons. Changes in gating kinetics or in expression levels of these channels by proinflammatory mediators are likely to cause the hyperexcitability of nociceptive neurons and pain hypersensitivity observed during inflammation. Proinflammatory mediator, tumor necrosis factor-α (TNF-α), is secreted during inflammation and is associated with the early onset, as well as long-lasting, inflammation-mediated increase in excitability of peripheral nociceptive neurons. Here we studied the underlying mechanisms of the rapid component of TNF-α-mediated nociceptive hyperexcitability and acute pain hypersensitivity. We showed that TNF-α leads to rapid onset, cyclooxygenase-independent pain hypersensitivity in adult rats. Furthermore, TNF-α rapidly and substantially increases nociceptive excitability in vitro, by decreasing action potential threshold, increasing neuronal gain and decreasing accommodation. We extended on previous studies entailing p38 MAPK-dependent increase in TTX-r sodium currents by showing that TNF-α via p38 MAPK leads to increased availability of TTX-r sodium channels by partial relief of voltage dependence of their slow inactivation, thereby contributing to increase in neuronal gain. Moreover, we showed that TNF-α also in a p38 MAPK-dependent manner increases persistent TTX-r current by shifting the voltage dependence of activation to a hyperpolarized direction, thus producing an increase in inward current at functionally critical subthreshold voltages. Our results suggest that rapid modulation of the gating of TTX-r sodium channels plays a major role in the mediated nociceptive hyperexcitability of TNF-α during acute inflammation and may lead to development of effective treatments for inflammatory pain, without modulating the inflammation-induced healing processes.
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Affiliation(s)
- Sagi Gudes
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Yaki Caspi
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Ben Katz
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel; and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
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43
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Nakamura M, Jang IS. Acid modulation of tetrodotoxin-resistant Na⁺ channels in rat nociceptive neurons. Neuropharmacology 2014; 90:82-9. [PMID: 25437826 DOI: 10.1016/j.neuropharm.2014.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 10/06/2014] [Accepted: 11/13/2014] [Indexed: 01/29/2023]
Abstract
Under pathological conditions including inflammation, ischemia and incision, extracellular pH falls down as low as 5.4. Although some mediators play pivotal roles in the development and maintenance of inflammatory hyperalgesia by affecting the functional properties of tetrodotoxin-resistant (TTX-R) Na(+) channels, the roles of tissue acidosis in nociceptive transmission mediated by TTX-R Na(+) channels are largely unknown. In the present study, we have investigated the effect of acidic pH on TTX-R Na(+) currents (I(Na)) in small-sized sensory neurons isolated from rat trigeminal ganglia using a whole-cell patch clamp technique. Acidic pH decreased the peak amplitude of TTX-R I(Na) in a pH-dependent manner, but weak acid (≥pH 6.0) had a minor inhibitory effect on the TTX-R I(Na). Acidic pH also significantly shifted both the activation and steady-state fast inactivation relationships toward depolarized potentials. In addition, acidic pH had little effect on the use-dependent inhibition, and significantly retarded the development of inactivation and accelerated the recovery from inactivation of TTX-R Na(+) channels. The results suggest that weak acid (≥pH 6.0) makes TTX-R Na(+) channels to be suitable for the repetitive activation at depolarized membrane potentials. Given that both tissue acidosis and inflammatory mediators in inflamed or injured tissues act synergistically to promote nociceptive transmission by affecting the functional properties of TTX-R Na(+) channels, these channels would be, at least in part, a good target to treat inflammatory pain.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea.
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44
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Kadala A, Charreton M, Jakob I, Cens T, Rousset M, Chahine M, Le Conte Y, Charnet P, Collet C. Pyrethroids differentially alter voltage-gated sodium channels from the honeybee central olfactory neurons. PLoS One 2014; 9:e112194. [PMID: 25390654 PMCID: PMC4229128 DOI: 10.1371/journal.pone.0112194] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/13/2014] [Indexed: 11/29/2022] Open
Abstract
The sensitivity of neurons from the honey bee olfactory system to pyrethroid insecticides was studied using the patch-clamp technique on central ‘antennal lobe neurons’ (ALNs) in cell culture. In these neurons, the voltage-dependent sodium currents are characterized by negative potential for activation, fast kinetics of activation and inactivation, and the presence of cumulative inactivation during train of depolarizations. Perfusion of pyrethroids on these ALN neurons submitted to repetitive stimulations induced (1) an acceleration of cumulative inactivation, and (2) a marked slowing of the tail current recorded upon repolarization. Cypermethrin and permethrin accelerated cumulative inactivation of the sodium current peak in a similar manner and tetramethrin was even more effective. The slow-down of channel deactivation was markedly dependent on the type of pyrethroid. With cypermethrin, a progressive increase of the tail current amplitude along with successive stimulations reveals a traditionally described use-dependent recruitment of modified sodium channels. However, an unexpected decrease in this tail current was revealed with tetramethrin. If one considers the calculated percentage of modified channels as an index of pyrethroids effects, ALNs are significantly more susceptible to tetramethrin than to permethrin or cypermethrin for a single depolarization, but this difference attenuates with repetitive activity. Further comparison with peripheral neurons from antennae suggest that these modifications are neuron type specific. Modeling the sodium channel as a multi-state channel with fast and slow inactivation allows to underline the effects of pyrethroids on a set of rate constants connecting open and inactivated conformations, and give some insights to their specificity. Altogether, our results revealed a differential sensitivity of central olfactory neurons to pyrethroids that emphasize the ability for these compounds to impair detection and processing of information at several levels of the bees olfactory pathway.
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Affiliation(s)
- Aklesso Kadala
- INRA, UR 406 Abeilles et Environnement, Toxicologie Environnementale, Avignon, France
| | - Mercedes Charreton
- INRA, UR 406 Abeilles et Environnement, Toxicologie Environnementale, Avignon, France
- UMT Protection des Abeilles dans l'Environnement, Avignon, France
| | - Ingrid Jakob
- INRA, UR 406 Abeilles et Environnement, Toxicologie Environnementale, Avignon, France
| | - Thierry Cens
- CNRS, UMR 5237, Centre de Recherche de Biochimie Macromoléculaire, Université Montpellier 2, Montpellier, France
| | - Matthieu Rousset
- CNRS, UMR 5237, Centre de Recherche de Biochimie Macromoléculaire, Université Montpellier 2, Montpellier, France
| | - Mohamed Chahine
- Department of medicine, Laval University, Québec city, Canada
| | - Yves Le Conte
- INRA, UR 406 Abeilles et Environnement, Toxicologie Environnementale, Avignon, France
- UMT Protection des Abeilles dans l'Environnement, Avignon, France
| | - Pierre Charnet
- CNRS, UMR 5237, Centre de Recherche de Biochimie Macromoléculaire, Université Montpellier 2, Montpellier, France
| | - Claude Collet
- INRA, UR 406 Abeilles et Environnement, Toxicologie Environnementale, Avignon, France
- UMT Protection des Abeilles dans l'Environnement, Avignon, France
- * E-mail:
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45
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Gingras J, Smith S, Matson DJ, Johnson D, Nye K, Couture L, Feric E, Yin R, Moyer BD, Peterson ML, Rottman JB, Beiler RJ, Malmberg AB, McDonough SI. Global Nav1.7 knockout mice recapitulate the phenotype of human congenital indifference to pain. PLoS One 2014; 9:e105895. [PMID: 25188265 PMCID: PMC4154897 DOI: 10.1371/journal.pone.0105895] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/25/2014] [Indexed: 12/19/2022] Open
Abstract
Clinical genetic studies have shown that loss of Nav1.7 function leads to the complete loss of acute pain perception. The global deletion is reported lethal in mice, however, and studies of mice with promoter-specific deletions of Nav1.7 have suggested that the role of Nav1.7 in pain transduction depends on the precise form of pain. We developed genetic and animal husbandry strategies that overcame the neonatal-lethal phenotype and enabled construction of a global Nav1.7 knockout mouse. Knockouts were anatomically normal, reached adulthood, and had phenotype wholly analogous to human congenital indifference to pain (CIP): compared to littermates, knockouts showed no defects in mechanical sensitivity or overall movement yet were completely insensitive to painful tactile, thermal, and chemical stimuli and were anosmic. Knockouts also showed no painful behaviors resulting from peripheral injection of nonselective sodium channel activators, did not develop complete Freund's adjuvant-induced thermal hyperalgesia, and were insensitive to intra-dermal histamine injection. Tetrodotoxin-sensitive sodium current recorded from cell bodies of isolated sensory neurons and the mechanically-evoked spiking of C-fibers in a skin-nerve preparation each were reduced but not eliminated in tissue from knockouts compared to littermates. Results support a role for Nav1.7 that is conserved between rodents and humans and suggest several possibly translatable biomarkers for the study of Nav1.7-targeted therapeutics. Results further suggest that Nav1.7 may retain its key role in persistent as well as acute forms of pain.
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Affiliation(s)
- Jacinthe Gingras
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Sarah Smith
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - David J. Matson
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Danielle Johnson
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Kim Nye
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Lauren Couture
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Elma Feric
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Ruoyuan Yin
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Bryan D. Moyer
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Matthew L. Peterson
- Department of Pharmaceutics Research & Development, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - James B. Rottman
- Department of Pathology, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Rudolph J. Beiler
- Department of Comparative Animal Research, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Annika B. Malmberg
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
| | - Stefan I. McDonough
- Department of Neuroscience, Amgen Inc., Cambridge, Massachusetts, United States of America
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46
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Bagal SK, Chapman ML, Marron BE, Prime R, Storer RI, Swain NA. Recent progress in sodium channel modulators for pain. Bioorg Med Chem Lett 2014; 24:3690-9. [PMID: 25060923 DOI: 10.1016/j.bmcl.2014.06.038] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/11/2014] [Accepted: 06/12/2014] [Indexed: 01/15/2023]
Abstract
Voltage-gated sodium channels (Navs) are an important family of transmembrane ion channel proteins and Nav drug discovery is an exciting field. Pharmaceutical investment in Navs for pain therapeutics has expanded exponentially due to genetic data such as SCN10A mutations and an improved ability to establish an effective screen sequence for example IonWorks Barracuda®, Synchropatch® and Qube®. Moreover, emerging clinical data (AZD-3161, XEN402, CNV1014802, PF-05089771, PF-04531083) combined with recent breakthroughs in Nav structural biology pave the way for a future of fruitful prospective Nav drug discovery.
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Affiliation(s)
- Sharan K Bagal
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, UK.
| | - Mark L Chapman
- Electrophysiology, Pfizer Neusentis, 4222 Emperor Blvd., Durham, NC, USA
| | - Brian E Marron
- Chemistry, Pfizer Neusentis, 4222 Emperor Blvd., Durham, NC, USA
| | - Rebecca Prime
- Electrophysiology, Pfizer Neusentis, The Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, UK
| | - R Ian Storer
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, UK
| | - Nigel A Swain
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, UK
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Modulation of peripheral Na+ channels and neuronal firing by n-butyl-p-aminobenzoate. Eur J Pharmacol 2014; 727:158-66. [DOI: 10.1016/j.ejphar.2014.01.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 01/15/2014] [Accepted: 01/22/2014] [Indexed: 11/21/2022]
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Abstract
The pseudounipolar sensory neurons of the dorsal root ganglia (DRG) give rise to peripheral branches that convert thermal, mechanical, and chemical stimuli into electrical signals that are transmitted via central branches to the spinal cord. These neurons express unique combinations of tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na(+) channels that contribute to the resting membrane potential, action potential threshold, and regulate neuronal firing frequency. The small-diameter neurons (<25 μm) isolated from the DRG represent the cell bodies of C-fiber nociceptors that express both TTX-S and TTX-R Na(+) currents. The large-diameter neurons (>35 μm) are typically low-threshold A-fibers that predominately express TTX-S Na(+) currents. Peripheral nerve damage, inflammation, and metabolic diseases alter the expression and function of these Na(+) channels leading to increases in neuronal excitability and pain. The Na(+) channels expressed in these neurons are the target of intracellular signaling cascades that regulate the trafficking, cell surface expression, and gating properties of these channels. Post-translational regulation of Na(+) channels by protein kinases (PKA, PKC, MAPK) alter the expression and function of the channels. Injury-induced changes in these signaling pathways have been linked to sensory neuron hyperexcitability and pain. This review examines the signaling pathways and regulatory mechanisms that modulate the voltage-gated Na(+) channels of sensory neurons.
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Affiliation(s)
- Mohamed Chahine
- Centre de recherche, Institut en santé mentale de Québec, Local F-6539, 2601, chemin de la Canardière, QC City, QC, Canada, G1J 2G3,
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Tigerholm J, Petersson ME, Obreja O, Lampert A, Carr R, Schmelz M, Fransén E. Modeling activity-dependent changes of axonal spike conduction in primary afferent C-nociceptors. J Neurophysiol 2013; 111:1721-35. [PMID: 24371290 DOI: 10.1152/jn.00777.2012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Action potential initiation and conduction along peripheral axons is a dynamic process that displays pronounced activity dependence. In patients with neuropathic pain, differences in the modulation of axonal conduction velocity by activity suggest that this property may provide insight into some of the pathomechanisms. To date, direct recordings of axonal membrane potential have been hampered by the small diameter of the fibers. We have therefore adopted an alternative approach to examine the basis of activity-dependent changes in axonal conduction by constructing a comprehensive mathematical model of human cutaneous C-fibers. Our model reproduced axonal spike propagation at a velocity of 0.69 m/s commensurate with recordings from human C-nociceptors. Activity-dependent slowing (ADS) of axonal propagation velocity was adequately simulated by the model. Interestingly, the property most readily associated with ADS was an increase in the concentration of intra-axonal sodium. This affected the driving potential of sodium currents, thereby producing latency changes comparable to those observed for experimental ADS. The model also adequately reproduced post-action potential excitability changes (i.e., recovery cycles) observed in vivo. We performed a series of control experiments replicating blockade of particular ion channels as well as changing temperature and extracellular ion concentrations. In the absence of direct experimental approaches, the model allows specific hypotheses to be formulated regarding the mechanisms underlying activity-dependent changes in C-fiber conduction. Because ADS might functionally act as a negative feedback to limit trains of nociceptor activity, we envisage that identifying its mechanisms may also direct efforts aimed at alleviating neuronal hyperexcitability in pain patients.
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Affiliation(s)
- Jenny Tigerholm
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden
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Galbavy W, Safaie E, Rebecchi MJ, Puopolo M. Inhibition of tetrodotoxin-resistant sodium current in dorsal root ganglia neurons mediated by D1/D5 dopamine receptors. Mol Pain 2013; 9:60. [PMID: 24283218 PMCID: PMC4220807 DOI: 10.1186/1744-8069-9-60] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/22/2013] [Indexed: 12/25/2022] Open
Abstract
Background Dopaminergic fibers originating from area A11 of the hypothalamus project to different levels of the spinal cord and represent the major source of dopamine. In addition, tyrosine hydroxylase, the rate-limiting enzyme for the synthesis of catecholamines, is expressed in 8-10% of dorsal root ganglia (DRG) neurons, suggesting that dopamine may be released in the dorsal root ganglia. Dopamine has been shown to modulate calcium current in DRG neurons, but the effects of dopamine on sodium current and on the firing properties of small DRG neurons are poorly understood. Results The effects of dopamine and dopamine receptor agonists were tested on the tetrodotoxin-resistant (TTX-R) sodium current recorded from acutely dissociated small (diameter ≤ 25 μm) DRG neurons. Dopamine (20 μM) and SKF 81297 (10 μM) caused inhibition of TTX-R sodium current in small DRG neurons by 23% and 37%, respectively. In contrast, quinpirole (20 μM) had no effects on the TTX-R sodium current. Inhibition by SKF 81297 of the TTX-R sodium current was not affected when the protein kinase A (PKA) activity was blocked with the PKA inhibitory peptide (6–22), but was greatly reduced when the protein kinase C (PKC) activity was blocked with the PKC inhibitory peptide (19–36), suggesting that activation of D1/D5 dopamine receptors is linked to PKC activity. Expression of D1and D5 dopamine receptors in small DRG neurons, but not D2 dopamine receptors, was confirmed by Western blotting and immunofluorescence analysis. In current clamp experiments, the number of action potentials elicited in small DRG neurons by current injection was reduced by ~ 30% by SKF 81297. Conclusions We conclude that activation of D1/D5 dopamine receptors inhibits TTX-R sodium current in unmyelinated nociceptive neurons and dampens their intrinsic excitability by reducing the number of action potentials in response to stimulus. Increasing or decreasing levels of dopamine in the dorsal root ganglia may serve to adjust the sensitivity of nociceptors to noxious stimuli.
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Affiliation(s)
| | | | | | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook Medicine, Stony Brook, NY 11794, USA.
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