1
|
Wang H, Zuo W, Feng X, Huo X, Liang Y, Wang B, Sharma D, Li X, Yasin B, Ye JH, Hu H, Tao YX. ESRRG-controlled downregulation of KCNN1 in primary sensory neurons is required for neuropathic pain. JCI Insight 2024; 9:e180085. [PMID: 38912580 DOI: 10.1172/jci.insight.180085] [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: 02/06/2024] [Accepted: 05/02/2024] [Indexed: 06/25/2024] Open
Abstract
Peripheral nerve injury-induced neuronal hyperactivity in the dorsal root ganglion (DRG) participates in neuropathic pain. The calcium-activated potassium channel subfamily N member 1 (KCNN1) mediates action potential afterhyperpolarization (AHP) and gates neuronal excitability. However, the specific contribution of DRG KCNN1 to neuropathic pain is not yet clear. We report that chronic constriction injury (CCI) of the unilateral sciatic nerve or unilateral ligation of the fourth lumbar nerve produced the downregulation of Kcnn1 mRNA and KCNN1 protein in the injured DRG. This downregulation was partially attributed to a decrease in DRG estrogen-related receptor gamma (ESRRG), a transcription factor, which led to reduced binding to the Kcnn1 promoter. Rescuing this downregulation prevented CCI-induced decreases in total potassium voltage currents and AHP currents, reduced excitability in the injured DRG neurons, and alleviated CCI-induced development and maintenance of nociceptive hypersensitivities, without affecting locomotor function and acute pain. Mimicking the CCI-induced DRG KCNN1 downregulation resulted in augmented responses to mechanical, heat, and cold stimuli in naive mice. Our findings indicate that ESRRG-controlled downregulation of DRG KCNN1 is likely essential for the development and maintenance of neuropathic pain. Thus, KCNN1 may serve as a potential target for managing this disorder.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Jiang-Hong Ye
- Department of Anesthesiology
- Department of Physiology, Pharmacology & Neuroscience; and
| | - Huijuan Hu
- Department of Anesthesiology
- Department of Physiology, Pharmacology & Neuroscience; and
| | - Yuan-Xiang Tao
- Department of Anesthesiology
- Department of Physiology, Pharmacology & Neuroscience; and
- Department of Cell Biology & Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| |
Collapse
|
2
|
Wang B, Liang Y, Bekker A, Hu H, Tao YX. Sensory neuron-specific long noncoding RNA in small non-peptidergic dorsal root ganglion neurons selectively impairs nerve injury-induced mechanical hypersensitivity. Life Sci 2023; 332:122120. [PMID: 37741322 PMCID: PMC10591916 DOI: 10.1016/j.lfs.2023.122120] [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: 08/05/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 09/25/2023]
Abstract
AIMS Nerve injury-induced mechanical hypersensitivity is one of major clinical symptoms in neuropathic pain patients. Understanding molecular mechanisms underlying this symptom is crucial for developing effective therapies. The present study was to investigate whether sensory neuron-specific long noncoding RNA (SS-lncRNA) predominantly expressed in small non-peptidergic dorsal root ganglion (DRG) neurons repaired nerve injury-induced mechanical hypersensitivity. MATERIALS AND METHODS SS-lncRNA downregulation in the mas-related G protein-coupled receptor member D (Mrgprd)-expressed DRG neurons was rescued and mimicked by crossbreeding MrgprdCreERT2/+ lines with Rosa26SS-lncRNA knock-in mice and SS-lncRNAfl/fl mice, respectively, followed by tamoxifen injection. KEY FINDINGS Rescuing SS-lncRNA downregulation in the Mrgprd-expressed DRG neurons significantly reversed the spinal nerve ligation (SNL)-induced reduction of the calcium-activated potassium channel subfamily N member 1 (KCNN1) in these DRG neurons and alleviated the SNL-induced mechanical hypersensitivity, without affecting the SNL-induced heat and cold nociceptive hypersensitivities, on the ipsilateral side. Conversely, mimicking SS-lncRNA downregulation in the Mrgprd-expressed DRG neurons reduced basal KCNN1 expression in these DRG neurons and produced the enhanced response to mechanical stimulation, but not thermal and cold stimuli, on bilateral sides. Mechanistically, SS-lncRNA downregulation caused a reduction in its binding to lysine-specific demethylase 6B (KDM6B) and consequent recruitment of less KDM6B to Kcnn1 promoter and an increase of H3K27me3 enrichment in this promoter in injured DRG. SIGNIFICANCE Our findings suggest that SS-lncRNA downregulation in small non-peptidergic sensory neurons is required specifically for nerve injury-induced mechanical hypersensitivity likely through silencing KCNN1 expression caused by KDM6B-gated increase of H3K27me3 enrichment in Kcnn1 promoter in these neurons.
Collapse
Affiliation(s)
- Bing Wang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yingping Liang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Alex Bekker
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Huijuan Hu
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA; Department of Physiology, Pharmacology & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yuan-Xiang Tao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA; Department of Physiology, Pharmacology & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA; Department of Cell Biology & Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA.
| |
Collapse
|
3
|
Wang B, Ma L, Guo X, Du S, Feng X, Liang Y, Govindarajalu G, Wu S, Liu T, Li H, Patel S, Bekker A, Hu H, Tao YX. A sensory neuron-specific long non-coding RNA reduces neuropathic pain by rescuing KCNN1 expression. Brain 2023; 146:3866-3884. [PMID: 37012681 PMCID: PMC10473565 DOI: 10.1093/brain/awad110] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 02/21/2023] [Accepted: 03/10/2023] [Indexed: 04/05/2023] Open
Abstract
Nerve injury to peripheral somatosensory system causes refractory neuropathic pain. Maladaptive changes of gene expression in primary sensory neurons are considered molecular basis of this disorder. Long non-coding RNAs (lncRNAs) are key regulators of gene transcription; however, their significance in neuropathic pain remains largely elusive.Here, we reported a novel lncRNA, named sensory neuron-specific lncRNA (SS-lncRNA), for its expression exclusively in dorsal root ganglion (DRG) and trigeminal ganglion. SS-lncRNA was predominantly expressed in small DRG neurons and significantly downregulated due to a reduction of early B cell transcription factor 1 in injured DRG after nerve injury. Rescuing this downregulation reversed a decrease of the calcium-activated potassium channel subfamily N member 1 (KCNN1) in injured DRG and alleviated nerve injury-induced nociceptive hypersensitivity. Conversely, DRG downregulation of SS-lncRNA reduced the expression of KCNN1, decreased total potassium currents and afterhyperpolarization currents and increased excitability in DRG neurons and produced neuropathic pain symptoms.Mechanistically, downregulated SS-lncRNA resulted in the reductions of its binding to Kcnn1 promoter and heterogeneous nuclear ribonucleoprotein M (hnRNPM), consequent recruitment of less hnRNPM to the Kcnn1 promoter and silence of Kcnn1 gene transcription in injured DRG.These findings indicate that SS-lncRNA may relieve neuropathic pain through hnRNPM-mediated KCNN1 rescue in injured DRG and offer a novel therapeutic strategy specific for this disorder.
Collapse
Affiliation(s)
- Bing Wang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Longfei Ma
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Xinying Guo
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Shibin Du
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Xiaozhou Feng
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yingping Liang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Gokulapriya Govindarajalu
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Shaogen Wu
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Tong Liu
- Center for Advanced Proteomics Research, Departments of Biochemistry, Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Hong Li
- Center for Advanced Proteomics Research, Departments of Biochemistry, Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Shivam Patel
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Alex Bekker
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Huijuan Hu
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
- Department of Physiology, Pharmacology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yuan-Xiang Tao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
- Department of Physiology, Pharmacology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| |
Collapse
|
4
|
Sahu G, Turner RW. The Molecular Basis for the Calcium-Dependent Slow Afterhyperpolarization in CA1 Hippocampal Pyramidal Neurons. Front Physiol 2022; 12:759707. [PMID: 35002757 PMCID: PMC8730529 DOI: 10.3389/fphys.2021.759707] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 12/02/2022] Open
Abstract
Neuronal signal transmission depends on the frequency, pattern, and timing of spike output, each of which are shaped by spike afterhyperpolarizations (AHPs). There are classically three post-spike AHPs of increasing duration categorized as fast, medium and slow AHPs that hyperpolarize a cell over a range of 10 ms to 30 s. Intensive early work on CA1 hippocampal pyramidal cells revealed that all three AHPs incorporate activation of calcium-gated potassium channels. The ionic basis for a fAHP was rapidly attributed to the actions of big conductance (BK) and the mAHP to small conductance (SK) or Kv7 potassium channels. In stark contrast, the ionic basis for a prominent slow AHP of up to 30 s duration remained an enigma for over 30 years. Recent advances in pharmacological, molecular, and imaging tools have uncovered the expression of a calcium-gated intermediate conductance potassium channel (IK, KCa3.1) in central neurons that proves to contribute to the slow AHP in CA1 hippocampal pyramidal cells. Together the data show that the sAHP arises in part from a core tripartite complex between Cav1.3 (L-type) calcium channels, ryanodine receptors, and IK channels at endoplasmic reticulum-plasma membrane junctions. Work on the sAHP in CA1 pyramidal neurons has again quickened pace, with identified contributions by both IK channels and the Na-K pump providing answers to several mysteries in the pharmacological properties of the sAHP.
Collapse
Affiliation(s)
- Giriraj Sahu
- National Institute of Pharmaceutical Education and Research Ahmedabad, Ahmedabad, India
| | - Ray W Turner
- Department Cell Biology & Anatomy, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| |
Collapse
|
5
|
Graham RD, Jhand AS, Lempka SF. Dorsal root ganglion stimulation produces differential effects on action potential propagation across a population of biophysically distinct C-neurons. FRONTIERS IN PAIN RESEARCH 2022; 3:1017344. [PMID: 36387415 PMCID: PMC9643723 DOI: 10.3389/fpain.2022.1017344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022] Open
Abstract
Dorsal root ganglion stimulation (DRGS) is a neurostimulation therapy used to manage chronic pain that does not respond to conventional therapies. Unfortunately, not all patients receive sufficient pain relief from DRGS, leaving them with few other treatment options. Presently, our understanding of the mechanisms of action of DRGS is incomplete, preventing us from determining why some patients do not receive analgesia from the therapy. One hypothesis suggests that DRGS augments the filtering of action potentials (APs) at the T-junction of nociceptive C-neurons. To test this hypothesis, we utilized a computational modeling approach in which we developed a population of one thousand biophysically distinct C-neuron models which each produced electrophysiological characteristics (e.g., AP height, AP duration) reported in previous experimental studies. We used this population of model C-neurons to study how morphological and electrophysiological characteristics affected the propagation of APs through the T-junction. We found that trains of APs can propagate through the T-junction in the orthodromic direction at a higher frequency than in the antidromic direction due to the decrease in axonal diameter from the peripheral to spinal axon. Including slow outward conductances in the axonal compartments near the T-junction reduced following frequencies to ranges measured experimentally. We next used the population of C-neuron models to investigate how DRGS affected the orthodromic propagation of APs through the T-junction. Our data suggest that suprathreshold DRGS augmented the filtering of APs at the T-junction of some model C-neurons while increasing the activity of other model C-neurons. However, the stimulus pulse amplitudes required to induce activity in C-neurons (i.e., several mA) fell outside the range of stimulation pulse amplitudes used clinically (i.e., typically ≤1 mA). Furthermore, our data suggest that somatic GABA currents activated directly or indirectly by the DRGS pulse may produce diverse effects on orthodromic AP propagation in C-neurons. These data suggest DRGS may produce differential effects across a population of C-neurons and indicate that understanding how inherent biological variability affects a neuron's response to therapeutic electrical stimulation may be helpful in understanding its mechanisms of action.
Collapse
Affiliation(s)
- Robert D Graham
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - Amolak S Jhand
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States.,Department of Anesthesiology, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
6
|
Zhao J, Zhang Y, Liu X, Rao Y, Fu J, Hua L, Ou C. Activation of SK3 channel plays a pivotal role in modulation of trigeminal neuralgia. Neurol Res 2021; 43:1005-1012. [PMID: 34233598 DOI: 10.1080/01616412.2021.1948765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Objective: To investigate whether small conductance Ca2+ activatedK+ channels; Trigeminal ganglion; Trigeminal neuralgia. (SK3) exists in normal rats' trigeminal ganglions (TG) and its effect on their pain thresholds.Methods: In total, 110 healthy adult male Sprague-Dawley (SD) rats were involved in this study. Ten rats were dissected to collect their liver tissues, TG and DRG. The rest of the rats were randomly assigned to either the experimental group or the control group. The animal model of trigeminal neuralgia (TN) was established by infraorbital nerve ligation. The expression of SK3 channels in their livers, TG and dorsal root ganglions (DRG) were detected. And different doses of SK3 channel activator and inhibitor were administered to the rats in both groups 15 days after the operation; meanwhile, their pain thresholds were also measured.Results: The expression of SK3 channel was found in TG. In the experimental group, the pain threshold was significantly decreased and there was a decreased level of SK3 than that in the control group at 15 days after operation. The administration of SK3 channel agonist (CyPPA) could significantly improve the pain threshold, while, the pain threshold decreased after administration of SK3 channel antagonist (Apamin).Conclusion: The SK3 channel may play a pivotal role in the pathogenesis of trigeminal neuralgia, and it may be one of the potential targets for the treatment of trigeminal neuralgia.
Collapse
Affiliation(s)
- Jiaomei Zhao
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Yue Zhang
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Xiangbo Liu
- Department of Pain Management, The Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan Province, China
| | - Yong Rao
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Jia Fu
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Lu Hua
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Cehua Ou
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| |
Collapse
|
7
|
Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
Collapse
Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
| |
Collapse
|
8
|
Wright H, Aylwin CF, Toro CA, Ojeda SR, Lomniczi A. Polycomb represses a gene network controlling puberty via modulation of histone demethylase Kdm6b expression. Sci Rep 2021; 11:1996. [PMID: 33479437 PMCID: PMC7819995 DOI: 10.1038/s41598-021-81689-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/08/2021] [Indexed: 12/13/2022] Open
Abstract
Female puberty is subject to Polycomb Group (PcG)-dependent transcriptional repression. Kiss1, a puberty-activating gene, is a key target of this silencing mechanism. Using a gain-of-function approach and a systems biology strategy we now show that EED, an essential PcG component, acts in the arcuate nucleus of the hypothalamus to alter the functional organization of a gene network involved in the stimulatory control of puberty. A central node of this network is Kdm6b, which encodes an enzyme that erases the PcG-dependent histone modification H3K27me3. Kiss1 is a first neighbor in the network; genes encoding glutamatergic receptors and potassium channels are second neighbors. By repressing Kdm6b expression, EED increases H3K27me3 abundance at these gene promoters, reducing gene expression throughout a gene network controlling puberty activation. These results indicate that Kdm6b repression is a basic mechanism used by PcG to modulate the biological output of puberty-activating gene networks.
Collapse
Affiliation(s)
- Hollis Wright
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Carlos F Aylwin
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Carlos A Toro
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Sergio R Ojeda
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Alejandro Lomniczi
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA.
| |
Collapse
|
9
|
Arnold LM, Blauwet MB, Tracy K, Cai N, Walzer M, Blahunka P, Marek GJ. Efficacy and Safety of ASP0819 in Patients with Fibromyalgia: Results of a Proof-of-Concept, Randomized, Double-Blind, Placebo-Controlled Trial. J Pain Res 2020; 13:3355-3369. [PMID: 33328761 PMCID: PMC7735791 DOI: 10.2147/jpr.s274562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/30/2020] [Indexed: 11/23/2022] Open
Abstract
PURPOSE ASP0819 is a novel, non-opioid KCa3.1 channel opener that reverses abnormal nerve firing of primary sensory afferent nerves. Currently available treatments for fibromyalgia provide only modest relief and are accompanied by a host of adverse side effects. PATIENTS AND METHODS In this phase 2a, double-blind trial (NCT03056690), adults meeting fibromyalgia diagnostic criteria were randomized 1:1 to receive either 15 mg/day of oral ASP0819 (n=91) or placebo (n=95). The primary endpoint was the change from baseline to Week 8 in the mean daily average pain score. Changes in the Fibromyalgia Impact Questionnaire Revised (FIQR) symptoms, function, and overall impact subscales, as well as changes in the patients' global impression of change, were secondary endpoints; treatment effects on FIQR total score and impact on sleep were exploratory analyses. RESULTS There was no statistically significant difference between ASP0819 and placebo for the primary endpoint (P=0.086); however, ASP0819 versus placebo significantly improved daily average pain at Weeks 2, 6, and 7 (all P<0.05). Numerical improvements were observed on the FIQR total score and several sleep items showed statistically significant improvements with ASP0819 versus placebo. There were no major safety concerns with ASP0819. Headache was the most common treatment-emergent adverse event (TEAE) occurring in both study arms; most TEAEs were mild or moderate in severity and no TEAEs suggestive of potential drug abuse were observed, as assessed by TEAE reporting and/or safety evaluations. Withdrawal effects also were not observed. CONCLUSION ASP0819 demonstrated some signals suggestive of efficacy and had a good tolerability profile in patients with fibromyalgia. Further studies are required to determine if ASP0819 can be a novel non-opioid treatment option in this patient group. CLINICALTRIALSGOV REGISTRATION NCT03056690.
Collapse
Affiliation(s)
- Leslie M Arnold
- University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | | | - Katherine Tracy
- Astellas Pharma Global Development, Inc, Northbrook, IL, USA
| | - Na Cai
- Astellas Pharma Global Development, Inc, Northbrook, IL, USA
| | - Mark Walzer
- Astellas Pharma Global Development, Inc, Northbrook, IL, USA
| | - Paul Blahunka
- Astellas Pharma Global Development, Inc, Northbrook, IL, USA
| | - Gerard J Marek
- Astellas Pharma Global Development, Inc, Northbrook, IL, USA
| |
Collapse
|
10
|
Smith PA. K + Channels in Primary Afferents and Their Role in Nerve Injury-Induced Pain. Front Cell Neurosci 2020; 14:566418. [PMID: 33093824 PMCID: PMC7528628 DOI: 10.3389/fncel.2020.566418] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/21/2020] [Indexed: 12/12/2022] Open
Abstract
Sensory abnormalities generated by nerve injury, peripheral neuropathy or disease are often expressed as neuropathic pain. This type of pain is frequently resistant to therapeutic intervention and may be intractable. Numerous studies have revealed the importance of enduring increases in primary afferent excitability and persistent spontaneous activity in the onset and maintenance of peripherally induced neuropathic pain. Some of this activity results from modulation, increased activity and /or expression of voltage-gated Na+ channels and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. K+ channels expressed in dorsal root ganglia (DRG) include delayed rectifiers (Kv1.1, 1.2), A-channels (Kv1.4, 3.3, 3.4, 4.1, 4.2, and 4.3), KCNQ or M-channels (Kv7.2, 7.3, 7.4, and 7.5), ATP-sensitive channels (KIR6.2), Ca2+-activated K+ channels (KCa1.1, 2.1, 2.2, 2.3, and 3.1), Na+-activated K+ channels (KCa4.1 and 4.2) and two pore domain leak channels (K2p; TWIK related channels). Function of all K+ channel types is reduced via a multiplicity of processes leading to altered expression and/or post-translational modification. This also increases excitability of DRG cell bodies and nociceptive free nerve endings, alters axonal conduction and increases neurotransmitter release from primary afferent terminals in the spinal dorsal horn. Correlation of these cellular changes with behavioral studies provides almost indisputable evidence for K+ channel dysfunction in the onset and maintenance of neuropathic pain. This idea is underlined by the observation that selective impairment of just one subtype of DRG K+ channel can produce signs of pain in vivo. Whilst it is established that various mediators, including cytokines and growth factors bring about injury-induced changes in DRG function and excitability, evidence presently available points to a seminal role for interleukin 1β (IL-1β) in control of K+ channel function. Despite the current state of knowledge, attempts to target K+ channels for therapeutic pain management have met with limited success. This situation may change with the advent of personalized medicine. Identification of specific sensory abnormalities and genetic profiling of individual patients may predict therapeutic benefit of K+ channel activators.
Collapse
Affiliation(s)
- Peter A. Smith
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
11
|
Jonas R, Prato V, Lechner SG, Groen G, Obreja O, Werland F, Rukwied R, Klusch A, Petersen M, Carr RW, Schmelz M. TTX-Resistant Sodium Channels Functionally Separate Silent From Polymodal C-nociceptors. Front Cell Neurosci 2020; 14:13. [PMID: 32116559 PMCID: PMC7018684 DOI: 10.3389/fncel.2020.00013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 01/17/2020] [Indexed: 01/09/2023] Open
Abstract
Pronounced activity-dependent slowing of conduction has been used to characterize mechano-insensitive, “silent” nociceptors and might be due to high expression of NaV1.8 and could, therefore, be characterized by their tetrodotoxin-resistance (TTX-r). Nociceptor-class specific differences in action potential characteristics were studied by: (i) in vitro calcium imaging in single porcine nerve growth factor (NGF)-responsive neurites; (ii) in vivo extracellular recordings in functionally identified porcine silent nociceptors; and (iii) in vitro patch-clamp recordings from murine silent nociceptors, genetically defined by nicotinic acetylcholine receptor subunit alpha-3 (CHRNA3) expression. Porcine TTX-r neurites (n = 26) in vitro had more than twice as high calcium transients per action potential as compared to TTX-s neurites (n = 18). In pig skin, silent nociceptors (n = 14) characterized by pronounced activity-dependent slowing of conduction were found to be TTX-r, whereas polymodal nociceptors were TTX-s (n = 12) and had only moderate slowing. Mechano-insensitive cold nociceptors were also TTX-r but showed less activity-dependent slowing than polymodal nociceptors. Action potentials in murine silent nociceptors differed from putative polymodal nociceptors by longer duration and higher peak amplitudes. Longer duration AP in silent murine nociceptors linked to increased sodium load would be compatible with a pronounced activity-dependent slowing in pig silent nociceptors and longer AP durations could be in line with increased calcium transients per action potential observed in vitro in TTX-resistant NGF responsive porcine neurites. Even though there is no direct link between slowing and TTX-resistant channels, the results indicate that axons of silent nociceptors not only differ in their receptive but also in their axonal properties.
Collapse
Affiliation(s)
- Robin Jonas
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Vincenzo Prato
- Institute of Pharmacology, University of Heidelberg, Heidelberg, Germany
| | - Stefan G Lechner
- Institute of Pharmacology, University of Heidelberg, Heidelberg, Germany
| | - Gerbrand Groen
- Department of Anesthesiology, Groningen University, Groningen, Netherlands
| | - Otilia Obreja
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Fiona Werland
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Andreas Klusch
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Marlen Petersen
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Richard W Carr
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| |
Collapse
|
12
|
Haberberger RV, Barry C, Dominguez N, Matusica D. Human Dorsal Root Ganglia. Front Cell Neurosci 2019; 13:271. [PMID: 31293388 PMCID: PMC6598622 DOI: 10.3389/fncel.2019.00271] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/04/2019] [Indexed: 12/14/2022] Open
Abstract
Sensory neurons with cell bodies situated in dorsal root ganglia convey information from external or internal sites of the body such as actual or potential harm, temperature or muscle length to the central nervous system. In recent years, large investigative efforts have worked toward an understanding of different types of DRG neurons at transcriptional, translational, and functional levels. These studies most commonly rely on data obtained from laboratory animals. Human DRG, however, have received far less investigative focus over the last 30 years. Nevertheless, knowledge about human sensory neurons is critical for a translational research approach and future therapeutic development. This review aims to summarize both historical and emerging information about the size and location of human DRG, and highlight advances in the understanding of the neurochemical characteristics of human DRG neurons, in particular nociceptive neurons.
Collapse
Affiliation(s)
- Rainer Viktor Haberberger
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Anatomy and Histology, Flinders University, Adelaide, SA, Australia.,Órama Institute, Flinders University, Adelaide, SA, Australia
| | - Christine Barry
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Anatomy and Histology, Flinders University, Adelaide, SA, Australia
| | - Nicholas Dominguez
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Anatomy and Histology, Flinders University, Adelaide, SA, Australia
| | - Dusan Matusica
- Pain and Pulmonary Neurobiology Laboratory, Centre for Neuroscience, Anatomy and Histology, Flinders University, Adelaide, SA, Australia.,Órama Institute, Flinders University, Adelaide, SA, Australia
| |
Collapse
|
13
|
Nigenda‐Morales SF, Hu Y, Beasley JC, Ruiz‐Piña HA, Valenzuela‐Galván D, Wayne RK. Transcriptomic analysis of skin pigmentation variation in the Virginia opossum (
Didelphis virginiana
). Mol Ecol 2018; 27:2680-2697. [DOI: 10.1111/mec.14712] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 04/05/2018] [Accepted: 04/17/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Sergio F. Nigenda‐Morales
- Department of Ecology and Evolutionary Biology University of California, Los Angeles Los Angeles California
| | - Yibo Hu
- Key Lab of Animal Ecology and Conservation Biology Institute of Zoology Chinese Academy of Sciences Chaoyang, Beijing China
| | - James C. Beasley
- Savannah River Ecology Lab Warnell School of Forestry and Natural Resources University of Georgia Aiken South Carolina
| | - Hugo A. Ruiz‐Piña
- Centro de Investigaciones Regionales “Dr. Hideyo Noguchi” Universidad Autónoma de Yucatán Mérida Yucatán Mexico
| | - David Valenzuela‐Galván
- Departamento de Ecología Evolutiva Centro de Investigación en Biodiversidad y Conservación Universidad Autónoma del Estado de Morelos Cuernavaca Morelos Mexico
| | - Robert K. Wayne
- Department of Ecology and Evolutionary Biology University of California, Los Angeles Los Angeles California
| |
Collapse
|
14
|
Zhang Q, Li S, Wong HTC, He XJ, Beirl A, Petralia RS, Wang YX, Kindt KS. Synaptically silent sensory hair cells in zebrafish are recruited after damage. Nat Commun 2018; 9:1388. [PMID: 29643351 PMCID: PMC5895622 DOI: 10.1038/s41467-018-03806-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 03/09/2018] [Indexed: 01/31/2023] Open
Abstract
Analysis of mechanotransduction among ensembles of sensory hair cells in vivo is challenging in many species. To overcome this challenge, we used optical indicators to investigate mechanotransduction among collections of hair cells in intact zebrafish. Our imaging reveals a previously undiscovered disconnect between hair-cell mechanosensation and synaptic transmission. We show that saturating mechanical stimuli able to open mechanically gated channels are unexpectedly insufficient to evoke vesicle fusion in the majority of hair cells. Although synaptically silent, latent hair cells can be rapidly recruited after damage, demonstrating that they are synaptically competent. Therefore synaptically silent hair cells may be an important reserve that acts to maintain sensory function. Our results demonstrate a previously unidentified level of complexity in sculpting sensory transmission from the periphery.
Collapse
Affiliation(s)
- Qiuxiang Zhang
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Suna Li
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hiu-Tung C Wong
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Xinyi J He
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alisha Beirl
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA
| | - Katie S Kindt
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, 20892, USA.
| |
Collapse
|
15
|
Jiménez-Vargas JM, Possani LD, Luna-Ramírez K. Arthropod toxins acting on neuronal potassium channels. Neuropharmacology 2017; 127:139-160. [PMID: 28941737 DOI: 10.1016/j.neuropharm.2017.09.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 01/01/2023]
Abstract
Arthropod venoms are a rich mixture of biologically active compounds exerting different physiological actions across diverse phyla and affecting multiple organ systems including the central nervous system. Venom compounds can inhibit or activate ion channels, receptors and transporters with high specificity and affinity providing essential insights into ion channel function. In this review, we focus on arthropod toxins (scorpions, spiders, bees and centipedes) acting on neuronal potassium channels. A brief description of the K+ channels classification and structure is included and a compendium of neuronal K+ channels and the arthropod toxins that modify them have been listed. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
Collapse
Affiliation(s)
- Juana María Jiménez-Vargas
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Karen Luna-Ramírez
- Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
| |
Collapse
|
16
|
Lu R, Flauaus C, Kennel L, Petersen J, Drees O, Kallenborn-Gerhardt W, Ruth P, Lukowski R, Schmidtko A. K Ca3.1 channels modulate the processing of noxious chemical stimuli in mice. Neuropharmacology 2017; 125:386-395. [PMID: 28823609 DOI: 10.1016/j.neuropharm.2017.08.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/26/2017] [Accepted: 08/16/2017] [Indexed: 12/19/2022]
Abstract
Intermediate conductance calcium-activated potassium channels (KCa3.1) have been recently implicated in pain processing. However, the functional role and localization of KCa3.1 in the nociceptive system are largely unknown. We here characterized the behavior of mice lacking KCa3.1 (KCa3.1-/-) in various pain models and analyzed the expression pattern of KCa3.1 in dorsal root ganglia (DRG) and the spinal cord. KCa3.1-/- mice demonstrated normal behavioral responses in models of acute nociceptive, persistent inflammatory, and persistent neuropathic pain. However, their behavioral responses to noxious chemical stimuli such as formalin and capsaicin were increased. Accordingly, formalin-induced nociceptive behavior was increased in wild-type mice after administration of the KCa3.1 inhibitor TRAM-34. In situ hybridization experiments detected KCa3.1 in most DRG satellite glial cells, in a minority of DRG neurons, and in ependymal cells lining the central canal of the spinal cord. Together, our data point to a specific inhibitory role of KCa3.1 for the processing of noxious chemical stimuli.
Collapse
Affiliation(s)
- Ruirui Lu
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany.
| | - Cathrin Flauaus
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Lea Kennel
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Jonas Petersen
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| | - Oliver Drees
- Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| | - Wiebke Kallenborn-Gerhardt
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Peter Ruth
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Universität Tübingen, 72076 Tübingen, Germany
| | - Robert Lukowski
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Universität Tübingen, 72076 Tübingen, Germany
| | - Achim Schmidtko
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| |
Collapse
|
17
|
Dale E, Staal RGW, Eder C, Möller T. KCa 3.1-a microglial target ready for drug repurposing? Glia 2016; 64:1733-41. [PMID: 27121595 DOI: 10.1002/glia.22992] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/29/2016] [Accepted: 04/03/2016] [Indexed: 01/25/2023]
Abstract
Over the past decade, glial cells have attracted attention for harboring unexploited targets for drug discovery. Several glial targets have attracted de novo drug discovery programs, as highlighted in this GLIA Special Issue. Drug repurposing, which has the objective of utilizing existing drugs as well as abandoned, failed, or not yet pursued clinical development candidates for new indications, might provide a faster opportunity to bring drugs for glial targets to patients with unmet needs. Here, we review the potential of the intermediate-conductance calcium-activated potassium channels KCa 3.1 as the target for such a repurposing effort. We discuss the data on KCa 3.1 expression on microglia in vitro and in vivo and review the relevant literature on the two KCa 3.1 inhibitors TRAM-34 and Senicapoc. Finally, we provide an outlook of what it might take to harness the potential of KCa 3.1 as a bona fide microglial drug target. GLIA 2016;64:1733-1741.
Collapse
Affiliation(s)
- Elena Dale
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
| | - Roland G W Staal
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
| | - Claudia Eder
- Institute for Infection and Immunity, St. George's, University of London, United Kingdom
| | - Thomas Möller
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
| |
Collapse
|
18
|
Abstract
Neuropathic pain often fails to respond to conventional pain management procedures. here we review the aetiology of neuropathic pain as would result from peripheral neuropathy or injury. We show that inflammatory mediators released from damaged nerves and tissue are responsible for triggering ectopic activity in primary afferents and that this, in turn, provokes increased spinal cord activity and the development of ‘central sensitization’. Although evidence is mounting to support the role of interleukin-1β, prostaglandins and other cytokines in the onset of neuropathic pain, the clinical efficacy of drugs which antagonize or prevent the actions of these mediators is yet to be determined. basic science findings do, however, support the use of pre-emptive analgesia during procedures which involve nerve manipulation and the use of anti-inflammatory steroids as soon as possible following traumatic nerve injury.
Collapse
|
19
|
Neuronal expression of the intermediate conductance calcium-activated potassium channel KCa3.1 in the mammalian central nervous system. Pflugers Arch 2014; 467:311-28. [PMID: 24797146 DOI: 10.1007/s00424-014-1523-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 01/09/2023]
Abstract
The expression pattern and functional roles for calcium-activated potassium channels of the KCa2.x family and KCa1.1 have been extensively examined in central neurons. Recent work indicates that intermediate conductance calcium-activated potassium channels (KCa3.1) are also expressed in central neurons of the cerebellum and spinal cord. The current study used immunocytochemistry and GFP linked to KCNN4 promoter activity in a transgenic mouse to determine the expression pattern of KCa3.1 channels in rat or mouse neocortex, hippocampus, thalamus, and cerebellum. KCa3.1 immunolabel and GFP expression were closely matched and detected in both excitatory and inhibitory cells of all regions examined. KCa3.1 immunolabel was localized primarily to the somatic region of excitatory cells in cortical structures but at the soma and over longer segments of dendrites of cells in deep cerebellar nuclei. More extensive labeling was apparent for inhibitory cells at the somatic and dendritic level with no detectable label associated with axon tracts or regions of intense synaptic innervation. The data indicate that KCa3.1 channels are expressed in the CNS with a differential pattern of distribution between cells, suggesting important functional roles for these calcium-activated potassium channels in regulating the excitability of central neurons.
Collapse
|
20
|
Waxman SG, Zamponi GW. Regulating excitability of peripheral afferents: emerging ion channel targets. Nat Neurosci 2014; 17:153-63. [DOI: 10.1038/nn.3602] [Citation(s) in RCA: 285] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/08/2013] [Indexed: 12/13/2022]
|
21
|
Opening paths to novel analgesics: the role of potassium channels in chronic pain. Trends Neurosci 2014; 37:146-58. [PMID: 24461875 PMCID: PMC3945816 DOI: 10.1016/j.tins.2013.12.002] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/02/2023]
Abstract
Potassium (K+) channels are crucial determinants of neuronal excitability. Nerve injury or inflammation alters K+ channel activity in neurons of the pain pathway. These changes can render neurons hyperexcitable and cause chronic pain. Therapies targeting K+ channels may provide improved pain relief in these states.
Chronic pain is associated with abnormal excitability of the somatosensory system and remains poorly treated in the clinic. Potassium (K+) channels are crucial determinants of neuronal activity throughout the nervous system. Opening of these channels facilitates a hyperpolarizing K+ efflux across the plasma membrane that counteracts inward ion conductance and therefore limits neuronal excitability. Accumulating research has highlighted a prominent involvement of K+ channels in nociceptive processing, particularly in determining peripheral hyperexcitability. We review salient findings from expression, pharmacological, and genetic studies that have untangled a hitherto undervalued contribution of K+ channels in maladaptive pain signaling. These emerging data provide a framework to explain enigmatic pain syndromes and to design novel pharmacological treatments for these debilitating states.
Collapse
|
22
|
Theophylline inhibits the cough reflex through a novel mechanism of action. J Allergy Clin Immunol 2014; 133:1588-98. [PMID: 24406072 PMCID: PMC4048545 DOI: 10.1016/j.jaci.2013.11.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 11/08/2013] [Accepted: 11/19/2013] [Indexed: 01/25/2023]
Abstract
Background Theophylline has been used in the treatment of asthma and chronic obstructive pulmonary disease for more than 80 years. In addition to bronchodilator and anti-inflammatory activity, clinical studies have suggested that theophylline acts as an antitussive agent. Cough is the most frequent reason for consultation with a family doctor, and treatment options are limited. Determining how theophylline inhibits cough might lead to the development of optimized compounds. Objective We sought to investigate the inhibitory activity of theophylline on vagal sensory nerve activity and the cough reflex. Methods Using a range of techniques, we investigated the effect of theophylline on human and guinea pig vagal sensory nerve activity in vitro and on the cough reflex in guinea pig challenge models. Results Theophylline was antitussive in a guinea pig model, inhibited activation of single C-fiber afferents in vivo and depolarization of human and guinea pig vagus in vitro, and inhibited calcium influx in airway-specific neurons in vitro. A sequence of pharmacological studies on the isolated vagus and patch clamp and single-channel inside-out experiments showed that the effect of theophylline was due to an increase in the open probability of calcium-activated potassium channels. Finally, we demonstrated the antitussive activity of theophylline in a cigarette smoke exposure model that exhibited enhanced tussive responses to capsaicin. Conclusion Theophylline inhibits capsaicin-induced cough under both normal and “disease” conditions by decreasing the excitability of sensory nerves through activation of small- and intermediate-conductance calcium-activated potassium channels. These findings could lead to the development of optimized antitussive compounds with a reduced side effect potential.
Collapse
|
23
|
Cabo R, Zichichi R, Viña E, Guerrera MC, Vázquez G, García-Suárez O, Vega JA, Germanà A. Calcium-activated potassium channel SK1 is widely expressed in the peripheral nervous system and sensory organs of adult zebrafish. Neurosci Lett 2013; 555:62-7. [PMID: 24060674 DOI: 10.1016/j.neulet.2013.09.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 06/13/2013] [Accepted: 09/10/2013] [Indexed: 10/26/2022]
Abstract
Sensory cells contain ion channels involved in the organ-specific transduction mechanisms that convert different types of stimuli into electric energy. Here we focus on small-conductance calcium-activated potassium channel 1 (SK1) which plays an important role in all excitable cells acting as feedback regulators in after-hyperpolarization. This study was undertaken to analyze the pattern of expression of SK1 in the zebrafish peripheral nervous system and sensory organs using RT-PRC, Westernblot and immunohistochemistry. Expression of SK1 mRNA was observed at all developmental stages analyzed (from 10 to 100 days post fertilization, dpf), and the antibody used identified a protein with a molecular weight of 70kDa, at 100dpf (regarded to be adult). Cell expressing SK1 in adult animals were neurons of dorsal root and cranial nerve sensory ganglia, sympathetic neurons, sensory cells in neuromasts of the lateral line system and taste buds, crypt olfactory neurons and photoreceptors. Present results report for the first time the expression and the distribution of SK1 in the peripheral nervous system and sensory organs of adult zebrafish, and may contribute to set zebrafish as an interesting experimental model for calcium-activated potassium channels research. Moreover these findings are of potential interest because the potential role of SK as targets for the treatment of neurological diseases and sensory disorders.
Collapse
Affiliation(s)
- R Cabo
- Departamento de Morfología y Biología Celular, Grupo SINPOS, Universidad de Oviedo, Spain
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Lambertsen KL, Gramsbergen JB, Sivasaravanaparan M, Ditzel N, Sevelsted-Møller LM, Oliván-Viguera A, Rabjerg M, Wulff H, Köhler R. Genetic KCa3.1-deficiency produces locomotor hyperactivity and alterations in cerebral monoamine levels. PLoS One 2012; 7:e47744. [PMID: 23077667 PMCID: PMC3471871 DOI: 10.1371/journal.pone.0047744] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/17/2012] [Indexed: 12/15/2022] Open
Abstract
Background The calmodulin/calcium-activated K+ channel KCa3.1 is expressed in red and white blood cells, epithelia and endothelia, and possibly central and peripheral neurons. However, our knowledge about its contribution to neurological functions and behavior is incomplete. Here, we investigated whether genetic deficiency or pharmacological activation of KCa3.1 change behavior and cerebral monoamine levels in mice. Methodology/Principal Findings In the open field test, KCa3.1-deficiency increased horizontal activity, as KCa3.1−/− mice travelled longer distances (≈145% of KCa3.1+/+) and at higher speed (≈1.5-fold of KCa3.1+/+). Working memory in the Y-maze was reduced by KCa3.1-deficiency. Motor coordination on the rotarod and neuromuscular functions were unchanged. In KCa3.1−/− mice, HPLC analysis revealed that turn-over rates of serotonin were reduced in frontal cortex, striatum and brain stem, while noradrenalin turn-over rates were increased in the frontal cortex. Dopamine turn-over rates were unaltered. Plasma catecholamine and corticosterone levels were unaltered. Intraperitoneal injections of 10 mg/kg of the KCa3.1/KCa2-activator SKA-31 reduced rearing and turning behavior in KCa3.1+/+ but not in KCa3.1−/− mice, while 30 mg/kg SKA-31 caused strong sedation in 50% of the animals of either genotypes. KCa3.1−/− mice were hyperactive (≈+60%) in their home cage and SKA-31-administration reduced nocturnal physical activity in KCa3.1+/+ but not in KCa3.1−/− mice. Conclusions/Significance KCa3.1-deficiency causes locomotor hyperactivity and altered monoamine levels in selected brain regions, suggesting a so far unknown functional link of KCa3.1 channels to behavior and monoaminergic neurotransmission in mice. The tranquilizing effects of low-dose SKA-31 raise the possibility to use KCa3.1/KCa2 channels as novel pharmacological targets for the treatment of neuropsychiatric hyperactivity disorders.
Collapse
Affiliation(s)
| | - Jan Bert Gramsbergen
- Department of Neurobiology Research, University of Southern Demark, Odense, Denmark
| | | | - Nicholas Ditzel
- KMEB, Molecular Endocrinology, Odense University Hospital, Odense, Denmark
| | - Linda Maria Sevelsted-Møller
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | | | - Maj Rabjerg
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Heike Wulff
- Department of Pharmacology, University of California Davis, Davis, California, United States of America
| | - Ralf Köhler
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
- Aragon Institute of Health Sciences I+CS and ARAID, Zaragoza, Spain
- * E-mail:
| |
Collapse
|
25
|
Obreja O, Hirth M, Turnquist B, Rukwied R, Ringkamp M, Schmelz M. The Differential Effects of Two Sodium Channel Modulators on the Conductive Properties of C-Fibers in Pig Skin In Vivo. Anesth Analg 2012; 115:560-71. [DOI: 10.1213/ane.0b013e3182542843] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
26
|
Kuiper EFE, Nelemans A, Luiten P, Nijholt I, Dolga A, Eisel U. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration. Front Pharmacol 2012; 3:107. [PMID: 22701424 PMCID: PMC3372087 DOI: 10.3389/fphar.2012.00107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/19/2012] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium (KCa) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of KCa channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of KCa channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) and the intermediate-conductance (KCa3.1) channel. These channels are activated by submicromolar intracellular Ca2+ concentrations and are voltage independent. Of all KCa channels only the KCa2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of KCa channel activation revealed new roles for KCa2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, KCa2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of KCa2 and KCa3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer’s disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and KCa channel activation.
Collapse
Affiliation(s)
- Els F E Kuiper
- Molecular Neurobiology, University of Groningen Groningen, Netherlands
| | | | | | | | | | | |
Collapse
|
27
|
Stemkowski PL, Smith PA. Long-term IL-1β exposure causes subpopulation-dependent alterations in rat dorsal root ganglion neuron excitability. J Neurophysiol 2011; 107:1586-97. [PMID: 22170966 DOI: 10.1152/jn.00587.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The effect of interleukin-1β (IL-1β) on the electrical properties of sensory neurons was assessed at levels and exposure times comparable to those found in animal models of neuropathic pain. Experiments involved whole cell current-clamp recordings from rat dorsal root ganglion (DRG) neurons in defined-medium, neuron-enriched cultures. Five- to six-day exposure to 100 pM IL-1β produced subpopulation-dependent effects on DRG neurons. These included an increase in the excitability of medium-diameter and small-diameter isolectin B(4) (IB(4))-positive neurons that was comparable to that found after peripheral nerve injury. By contrast, a reduction in excitability was observed in large-diameter neurons, while no effect was found in small-diameter IB(4)-negative neurons. Further characterization of changes in medium and small IB(4)-positive neurons revealed that some, but not all, effects of IL-1β were mediated through its receptor, IL-1RI. Although the acute actions of IL-1β on sensory neurons have been well studied and related to acute and/or inflammatory pain, the present study shows how sensory neurons respond to long-term cytokine exposure. Such effects are relevant to understanding processes that contribute to the onset of neuropathic pain.
Collapse
|
28
|
Sandow S, Grayson TH. 'Altered' mesenteric artery SK(Ca) : functional implications? Br J Pharmacol 2011; 163:1115-7; author reply 1118-21. [PMID: 21707589 DOI: 10.1111/j.1476-5381.2011.01262.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
29
|
Liebau S, Tischendorf M, Ansorge D, Linta L, Stockmann M, Weidgang C, Iacovino M, Boeckers T, von Wichert G, Kyba M, Kleger A. An inducible expression system of the calcium-activated potassium channel 4 to study the differential impact on embryonic stem cells. Stem Cells Int 2011; 2011:456815. [PMID: 21941566 PMCID: PMC3173888 DOI: 10.4061/2011/456815] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 06/14/2011] [Indexed: 11/20/2022] Open
Abstract
Rationale. The family of calcium-activated potassium channels consists of four members with varying biological functions and conductances. Besides membrane potential modulation, SK channels have been found to be involved in cardiac pacemaker cell development from ES cells and morphological shaping of neural stem cells. Objective. Distinct SK channel subtype expression in ES cells might elucidate their precise impact during cardiac development. We chose SK channel subtype 4 as a potential candidate influencing embryonic stem cell differentiation. Methods. We generated a doxycycline inducible mouse ES cell line via targeted homologous recombination of a cassette expressing a bicistronic construct encoding SK4 and a fluorophore from the murine HPRT locus. Conclusion. We characterized the mouse ES cell line iSK4-AcGFP. The cassette is readily expressed under the control of doxycycline, and the overexpression of SK4 led to an increase in cardiac and pacemaker cell differentiation thereby serving as a unique tool to characterize the cell biological variances due to specific SK channel overexpression.
Collapse
Affiliation(s)
- Stefan Liebau
- Institute for Anatomy and Cell Biology, Ulm University, 89081 Ulm, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Obreja O, Ringkamp M, Turnquist B, Hirth M, Forsch E, Rukwied R, Petersen M, Schmelz M. Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors. Pain 2011; 152:2138-2146. [DOI: 10.1016/j.pain.2011.05.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 04/27/2011] [Accepted: 05/18/2011] [Indexed: 01/07/2023]
|
31
|
Dolga AM, Terpolilli N, Kepura F, Nijholt IM, Knaus HG, D'Orsi B, Prehn JHM, Eisel ULM, Plant T, Plesnila N, Culmsee C. KCa2 channels activation prevents [Ca2+]i deregulation and reduces neuronal death following glutamate toxicity and cerebral ischemia. Cell Death Dis 2011; 2:e147. [PMID: 21509037 PMCID: PMC3122061 DOI: 10.1038/cddis.2011.30] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Exacerbated activation of glutamate receptor-coupled calcium channels and subsequent increase in intracellular calcium ([Ca2+]i) are established hallmarks of neuronal cell death in acute and chronic neurological diseases. Here we show that pathological [Ca2+]i deregulation occurring after glutamate receptor stimulation is effectively modulated by small conductance calcium-activated potassium (KCa2) channels. We found that neuronal excitotoxicity was associated with a rapid downregulation of KCa2.2 channels within 3 h after the onset of glutamate exposure. Activation of KCa2 channels preserved KCa2 expression and significantly reduced pathological increases in [Ca2+]i providing robust neuroprotection in vitro and in vivo. These data suggest a critical role for KCa2 channels in excitotoxic neuronal cell death and propose their activation as potential therapeutic strategy for the treatment of acute and chronic neurodegenerative disorders.
Collapse
Affiliation(s)
- A M Dolga
- Institut für Pharmakologie und Klinische Pharmazie, Fachbereich Pharmazie, Philipps-Universität Marburg, Marburg, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Chadha PS, Liu L, Rikard-Bell M, Senadheera S, Howitt L, Bertrand RL, Grayson TH, Murphy TV, Sandow SL. Endothelium-dependent vasodilation in human mesenteric artery is primarily mediated by myoendothelial gap junctions intermediate conductance calcium-activated K+ channel and nitric oxide. J Pharmacol Exp Ther 2011; 336:701-8. [PMID: 21172909 DOI: 10.1124/jpet.110.165795] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Myoendothelial microdomain signaling via localized calcium-activated potassium channel (K(Ca)) and gap junction connexins (Cx) is critical for endothelium-dependent vasodilation in rat mesenteric artery. The present study determines the relative contribution of NO and gap junction-K(Ca) mediated microdomain signaling to endothelium-dependent vasodilation in human mesenteric artery. The hypothesis tested was that such activity is due to NO and localized K(Ca) and Cx activity. In mesenteric arteries from intestinal surgery patients, endothelium-dependent vasodilation was characterized using pressure myography with pharmacological intervention. Vessel morphology was examined using immunohistochemical and ultrastructural techniques. In vessel segments at 80 mm Hg, the intermediate (I)K(Ca) blocker 1-[(2-chlorophenyl)diphenyl-methyl]-1H-pyrazole (TRAM-34; 1 μM) inhibited bradykinin (0.1 nM-3 μM)-induced vasodilation, whereas the small (S) K(Ca) blocker apamin (50 and 100 nM) had no effect. Direct IK(Ca) activation with 1-ethyl-2-benzimidazolinone (1-EBIO; 10-300 μM) induced vasodilation, whereas cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (1-30 μM), the SK(Ca) activator, failed to dilate arteries, whereas dilation induced by 1-EBIO (10-100 μM) was blocked by TRAM-34. Bradykinin-mediated vasodilation was attenuated by putative gap junction block with carbenoxolone (100 μM), with remaining dilation blocked by N-nitro l-arginine methyl ester (100 μM) and [1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (10 μM), NO synthase and soluble guanylate cyclase blockers, respectively. In human mesenteric artery, myoendothelial gap junction and IK(Ca) activity are consistent with Cx37 and IK(Ca) microdomain expression and distribution. Data suggest that endothelium-dependent vasodilation is primarily mediated by NO, IK(Ca), and gap junction Cx37 in this vessel. Myoendothelial microdomain signaling sites are present in human mesenteric artery and are likely to contribute to endothelium-dependent vasodilation via a mechanism that is conserved between species.
Collapse
Affiliation(s)
- Preet S Chadha
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Li BY, Glazebrook P, Kunze DL, Schild JH. KCa1.1 channel contributes to cell excitability in unmyelinated but not myelinated rat vagal afferents. Am J Physiol Cell Physiol 2011; 300:C1393-403. [PMID: 21325638 DOI: 10.1152/ajpcell.00278.2010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
High conductance calcium-activated potassium (BK(Ca)) channels can modulate cell excitability and neurotransmitter release at synaptic and afferent terminals. BK(Ca) channels are present in primary afferents of most, if not, all internal organs and are an intriguing target for pharmacological manipulation of visceral sensation. Our laboratory has a long-standing interest in the neurophysiological differences between myelinated and unmyelinated visceral afferent function. Here, we seek to determine whether there is a differential distribution of BK(Ca) channels in myelinated and unmyelinated vagal afferents. Immunocytochemistry studies with double staining for the BK-type K(Ca)1.1 channel protein and isolectin B4 (IB4), a reliable marker of unmyelinated peripheral afferents, reveal a pattern of IB4 labeling that strongly correlates with the expression of the K(Ca)1.1 channel protein. Measures of cell size and immunostaining intensity for K(Ca)1.1 and IB4 cluster into two statistically distinct (P < 0.05) populations of cells. Smaller diameter neurons most often presented with strong IB4 labeling and are presumed to be unmyelinated (n = 1,390) vagal afferents. Larger diameter neurons most often lacked or exhibited a very weak IB4 labeling and are presumed to be myelinated (n = 58) vagal afferents. Complimentary electrophysiological studies reveal that the BK(Ca) channel blockers charybdotoxin (ChTX) and iberiotoxin (IbTX) bring about a comparable elevation in excitability and action potential widening in unmyelinated neurons but had no effect on the excitability of myelinated vagal afferents. This study is the first to demonstrate using combined immunohistochemical and electrophysiological techniques that K(Ca)1.1 channels are uniquely expressed in unmyelinated C-type vagal afferents and do not contribute to the dynamic discharge characteristics of myelinated A-type vagal afferents. This unique functional distribution of BK-type K(Ca) channels may provide an opportunity for afferent selective pharmacological intervention across a wide range of visceral pathophysiologies, particularly those with a reflexogenic etiology and pain.
Collapse
Affiliation(s)
- Bai-Yan Li
- Dept. of Biomedical Engineering, Indiana University Purdue University, 723 W. Michigan St., Indianapolis, IN 46202, USA
| | | | | | | |
Collapse
|
34
|
Castañeda-Corral G, Jimenez-Andrade JM, Bloom AP, Taylor RN, Mantyh WG, Kaczmarska MJ, Ghilardi JR, Mantyh PW. The majority of myelinated and unmyelinated sensory nerve fibers that innervate bone express the tropomyosin receptor kinase A. Neuroscience 2011; 178:196-207. [PMID: 21277945 DOI: 10.1016/j.neuroscience.2011.01.039] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/16/2011] [Accepted: 01/20/2011] [Indexed: 12/13/2022]
Abstract
Although skeletal pain is a leading cause of chronic pain and disability, relatively little is known about the specific populations of nerve fibers that innervate the skeleton. Recent studies have reported that therapies blocking nerve growth factor (NGF) or its cognate receptor, tropomyosin receptor kinase A (TrkA) are efficacious in attenuating skeletal pain. A potential factor to consider when assessing the analgesic efficacy of targeting NGF-TrkA signaling in a pain state is the fraction of NGF-responsive TrkA+ nociceptors that innervate the tissue from which the pain is arising, as this innervation and the analgesic efficacy of targeting NGF-TrkA signaling may vary considerably from tissue to tissue. To explore this in the skeleton, tissue slices and whole mount preparations of the normal, adult mouse femur were analyzed using immunohistochemistry and confocal microscopy. Analysis of these preparations revealed that 80% of the unmyelinated/thinly myelinated sensory nerve fibers that express calcitonin gene-related peptide (CGRP) and innervate the periosteum, mineralized bone and bone marrow also express TrkA. Similarly, the majority of myelinated sensory nerve fibers that express neurofilament 200 kDa (NF200) which innervate the periosteum, mineralized bone and bone marrow also co-express TrkA. In the normal femur, the relative density of CGRP+, NF200+ and TrkA+ sensory nerve fibers per unit volume is: periosteum>bone marrow>mineralized bone>cartilage with the respective relative densities being 100:2:0.1:0. The observation that the majority of sensory nerve fibers innervating the skeleton express TrkA+, may in part explain why therapies that block NGF/TrkA pathway are highly efficacious in attenuating skeletal pain.
Collapse
Affiliation(s)
- G Castañeda-Corral
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Haddock RE, Grayson TH, Morris MJ, Howitt L, Chadha PS, Sandow SL. Diet-induced obesity impairs endothelium-derived hyperpolarization via altered potassium channel signaling mechanisms. PLoS One 2011; 6:e16423. [PMID: 21283658 PMCID: PMC3025034 DOI: 10.1371/journal.pone.0016423] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/15/2010] [Indexed: 11/20/2022] Open
Abstract
Background The vascular endothelium plays a critical role in the control of blood flow. Altered endothelium-mediated vasodilator and vasoconstrictor mechanisms underlie key aspects of cardiovascular disease, including those in obesity. Whilst the mechanism of nitric oxide (NO)-mediated vasodilation has been extensively studied in obesity, little is known about the impact of obesity on vasodilation to the endothelium-derived hyperpolarization (EDH) mechanism; which predominates in smaller resistance vessels and is characterized in this study. Methodology/Principal Findings Membrane potential, vessel diameter and luminal pressure were recorded in 4th order mesenteric arteries with pressure-induced myogenic tone, in control and diet-induced obese rats. Obesity, reflecting that of human dietary etiology, was induced with a cafeteria-style diet (∼30 kJ, fat) over 16–20 weeks. Age and sexed matched controls received standard chow (∼12 kJ, fat). Channel protein distribution, expression and vessel morphology were determined using immunohistochemistry, Western blotting and ultrastructural techniques. In control and obese rat vessels, acetylcholine-mediated EDH was abolished by small and intermediate conductance calcium-activated potassium channel (SKCa/IKCa) inhibition; with such activity being impaired in obesity. SKCa-IKCa activation with cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) and 1-ethyl-2-benzimidazolinone (1-EBIO), respectively, hyperpolarized and relaxed vessels from control and obese rats. IKCa-mediated EDH contribution was increased in obesity, and associated with altered IKCa distribution and elevated expression. In contrast, the SKCa-dependent-EDH component was reduced in obesity. Inward-rectifying potassium channel (Kir) and Na+/K+-ATPase inhibition by barium/ouabain, respectively, attenuated and abolished EDH in arteries from control and obese rats, respectively; reflecting differential Kir expression and distribution. Although changes in medial properties occurred, obesity had no effect on myoendothelial gap junction density. Conclusion/Significance In obese rats, vasodilation to EDH is impaired due to changes in the underlying potassium channel signaling mechanisms. Whilst myoendothelial gap junction density is unchanged in arteries of obese compared to control, increased IKCa and Na+/K+-ATPase, and decreased Kir underlie changes in the EDH mechanism.
Collapse
Affiliation(s)
- Rebecca E. Haddock
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- Department of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (REH); (SLS)
| | - T. Hilton Grayson
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Margaret J. Morris
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Lauren Howitt
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Preet S. Chadha
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Shaun L. Sandow
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail: (REH); (SLS)
| |
Collapse
|
36
|
Chadha PS, Haddock RE, Howitt L, Morris MJ, Murphy TV, Grayson TH, Sandow SL. Obesity Up-Regulates Intermediate Conductance Calcium-Activated Potassium Channels and Myoendothelial Gap Junctions to Maintain Endothelial Vasodilator Function. J Pharmacol Exp Ther 2010; 335:284-93. [DOI: 10.1124/jpet.110.167593] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
37
|
Schneider EM, Ma X, Stratz T, Müller W, Lorenz I, Seeling WD. Immunomodulatory function of the 5‐HT3receptor antagonist tropisetron. Scand J Rheumatol 2009. [DOI: 10.1080/03009740410007014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
38
|
Microneurographic single-unit recordings to assess receptive properties of afferent human C-fibers. Neurosci Lett 2009; 470:158-61. [PMID: 19481585 DOI: 10.1016/j.neulet.2009.05.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 04/24/2009] [Accepted: 05/20/2009] [Indexed: 11/16/2022]
Abstract
Action potentials in unmyelinated peripheral axons can be recorded in awake humans by microneurography with small electrodes placed in a peripheral nerve. This technique provides extracellular recordings of single C-fibers and thus enables characterization of their sensory and axonal properties. By using microneurographical basic properties of afferent C-fibers such as conduction velocities, innervation territories, sensory thresholds and chemical responsiveness were measured. Moreover, axonal excitability changes induced by repetitive activation were assessed. Sensory and axonal properties of the different fiber classes cluster. Based on those specific properties, unitary functional classes of nociceptors (such as polymodal nociceptors and mechano-insensitive nociceptors) and non-nociceptors (such as tactile afferents and warm fibers) were classified. With normal data available, sensitization and desensitization of afferent fibers have been found in pathophysiologic states as detected in chronic pain patients. As subjects and patients are awake during the recording, microneurography provides a unique tool to correlate the discharge behaviour of afferent nerve fibers with the sensation evoked by certain stimuli.
Collapse
|
39
|
Greffrath W, Schwarz ST, Büsselberg D, Treede RD. Heat-induced action potential discharges in nociceptive primary sensory neurons of rats. J Neurophysiol 2009; 102:424-36. [PMID: 19439674 DOI: 10.1152/jn.90916.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although several transducer molecules for noxious stimuli have been identified, little is known about the transformation of the resulting generator currents into action potentials (APs). Therefore we investigated the transformation process for stepped noxious heat stimuli (42-47 degrees C, 3-s duration) into membrane potential changes and subsequent AP discharges using the somata of acutely dissociated small dorsal root ganglion (DRG) neurons (diameter<or=32.5 microm) of adult rats as a model for their own peripheral terminals. Three types of heat-induced membrane potential changes were differentiated: type 1, heat-induced AP discharges (approximately 37% of the neurons); type 2, heat-induced membrane depolarization (40%); and type 3, responses not exceeding those of switching the superfusion (23%). Warming neurons from room temperature to 35 degrees C increased their background conductance, nearly doubled the AP threshold current, and led to smaller and narrower APs. Adaptation of heat-induced AP discharges was seen in about half of the type 1 neurons. The remaining half displayed accelerating discharges to both heat stimuli and depolarizing current injection. Repeated heat stimulation induced marked suppression of AP discharges. Under rapid calcium buffering using BAPTA, repolarization of heat-induced APs stopped at a plateau potential slowly decreasing from +16.5+/-2.9 to -2.2+/-5.5 mV, resulting in no further AP discharges. This study demonstrates that heat-induced AP discharges can be elicited in the soma of a subgroup of DRG neurons. These discharges display suppression on repetitive stimulation, but either adaptation or sensitization during prolonged stimuli. AP threshold and AP shape during these discharges suggest temperature dependence of background conductance and repolarizing currents.
Collapse
Affiliation(s)
- Wolfgang Greffrath
- Division of Neurophysiology, Center of Biomedicine and Medical Technology Mannheim, CBTM Ludolf-Krehl-Strasse 13-17, Medical Faculty Mannheim, Ruprecht-Karls-University Heidelberg, D-68167 Mannheim, Germany.
| | | | | | | |
Collapse
|
40
|
Chen SR, Cai YQ, Pan HL. Plasticity and emerging role of BKCa channels in nociceptive control in neuropathic pain. J Neurochem 2009; 110:352-62. [PMID: 19457113 DOI: 10.1111/j.1471-4159.2009.06138.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Large-conductance Ca(2+)-activated K(+) (BK(Ca), MaxiK) channels are important for the regulation of neuronal excitability. Peripheral nerve injury causes plasticity of primary afferent neurons and spinal dorsal horn neurons, leading to central sensitization and neuropathic pain. However, little is known about changes in the BK(Ca) channels in the dorsal root ganglion (DRG) and spinal dorsal horn and their role in the control of nociception in neuropathic pain. Here we show that L5 and L6 spinal nerve ligation in rats resulted in a substantial reduction in both the mRNA and protein levels of BK(Ca) channels in the DRG but not in the spinal cord. Nerve injury primarily reduced the BK(Ca) channel immunoreactivity in small- and medium-sized DRG neurons. Furthermore, although the BK(Ca) channel immunoreactivity was decreased in the lateral dorsal horn, there was an increase in the BK(Ca) channel immunoreactivity present on dorsal horn neurons near the dorsal root entry zone. Blocking the BK(Ca) channel with iberiotoxin at the spinal level significantly reduced the mechanical nociceptive withdrawal threshold in control and nerve-injured rats. Intrathecal injection of the BK(Ca) channel opener [1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one] dose dependently reversed allodynia and hyperalgesia in nerve-ligated rats but it had no significant effect on nociception in control rats. Our study provides novel information that nerve injury suppresses BK(Ca) channel expression in the DRG and induces a redistribution of BK(Ca) channels in the spinal dorsal horn. BK(Ca) channels are increasingly involved in the control of sensory input in neuropathic pain and may represent a new target for neuropathic pain treatment.
Collapse
Affiliation(s)
- Shao-Rui Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA
| | | | | |
Collapse
|
41
|
Molecular and cellular basis of small--and intermediate-conductance, calcium-activated potassium channel function in the brain. Cell Mol Life Sci 2008; 65:3196-217. [PMID: 18597044 PMCID: PMC2798969 DOI: 10.1007/s00018-008-8216-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Small conductance calcium-activated potassium (SK or KCa2) channels link intracellular calcium transients to membrane potential changes. SK channel subtypes present different pharmacology and distribution in the nervous system. The selective blocker apamin, SK enhancers and mice lacking specific SK channel subunits have revealed multifaceted functions of these channels in neurons, glia and cerebral blood vessels. SK channels regulate neuronal firing by contributing to the afterhyperpolarization following action potentials and mediating IAHP, and partake in a calcium-mediated feedback loop with NMDA receptors, controlling the threshold for induction of hippocampal long-term potentiation. The function of distinct SK channel subtypes in different neurons often results from their specific coupling to different calcium sources. The prominent role of SK channels in the modulation of excitability and synaptic function of limbic, dopaminergic and cerebellar neurons hints at their possible involvement in neuronal dysfunction, either as part of the causal mechanism or as potential therapeutic targets.
Collapse
|
42
|
The expression and function of Ca(2+)-sensing receptors in rat mesenteric artery; comparative studies using a model of type II diabetes. Br J Pharmacol 2008; 154:652-62. [PMID: 18414396 DOI: 10.1038/bjp.2008.108] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE The extracellular calcium-sensing receptor (CaR) in vascular endothelial cells activates endothelial intermediate-conductance, calcium-sensitive K(+) channels (IK(Ca)) indirectly leading to myocyte hyperpolarization. We determined whether CaR expression and function was modified in a rat model of type II diabetes. EXPERIMENTAL APPROACH Pressure myography, western blotting, sharp microelectrode and K(+)-selective electrode recordings were used to investigate the functional expression of the CaR and IK(Ca) in rat mesenteric arteries. KEY RESULTS Myocyte hyperpolarization to the CaR activator calindol was inhibited by Calhex 231. U46619-induced vessel contraction elevated the extracellular [K(+)] around the myocytes, and inhibition of this 'K(+) cloud' by iberiotoxin was needed to reveal calindol-induced vasodilatations. These were antagonized by Calhex 231 and significantly smaller in Zucker diabetic fatty rat (ZDF) vessels than in Zucker lean (ZL) controls. Myocyte hyperpolarizations to calindol were also smaller in ZDF than in ZL arteries. In ZDF vessels, endothelial cell CaR protein expression was reduced; IK(Ca) expression was also diminished, but IK(Ca)-generated hyperpolarizations mediated by 1-EBIO were unaffected. CONCLUSIONS AND IMPLICATIONS The reduced CaR-mediated hyperpolarizing and vasodilator responses in ZDF arteries result from a decrease in CaR expression, rather than from a modification of IK(Ca) channels. Detection of CaR-mediated vasodilatation required the presence of iberiotoxin, suggesting a CaR contribution to vascular diameter, that is, inversely related to the degree of vasoconstriction. Compromise of the CaR pathway would favour the long-term development of a higher basal vascular tone and could contribute to the vascular complications associated with type II diabetes.
Collapse
|
43
|
Burrell BD, Crisp KM. Serotonergic Modulation of Afterhyperpolarization in a Neuron That Contributes to Learning in the Leech. J Neurophysiol 2008; 99:605-16. [DOI: 10.1152/jn.00989.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Modulation of afterhyperpolarization (AHP) represents an important mechanism by which excitability of a neuron can be regulated. In the leech brain, sensitization enhances excitability of the S-cell, an interneuron thought to play an important role in this form of nonassociative learning. This increase in excitability is serotonin (5-HT) dependent, but it is not known whether changes in AHP contribute to 5-HT–mediated enhancement of excitability. Therefore electrophysiological recordings and computational modeling were used to determine whether 5-HT enhances excitability via modulation of AHP. 5-HT reduced S-cell AHP and this decrease in the AHP corresponded with an increase in excitability. Little or no AHP is observed in the presence of Ca2+-free saline, suggesting the involvement of Ca2+-dependent K+channels. Furthermore, AHP amplitude decreased following treatment with drugs (tubocurare and charybdotoxin) that block Ca2+-dependent K+channel activity. The S-cell also exhibits an afterdepolarization (ADP), which is usually masked by the AHP, and was inhibited by the Na+channel blocker saxitoxin. A model of the S-cell AHP was constructed using two Ca2+-dependent K+currents and a Na+-driven ADP current. Reduction of the model conductances underlying the AHP to mimic the effects of 5-HT was sufficient to enhance excitability. These findings were confirmed in occlusion experiments in which pretreatment with tubocurare was able to block 5-HT–mediated decreases in mAHP levels and increases in excitability. These data show that modulation of S-cell AHP can contribute to 5-HT–mediated increases in excitability and that the S-cell afterpotential is due to the combined effects of AHP- and ADP-producing currents.
Collapse
|
44
|
Rabert D, Xiao Y, Yiangou Y, Kreder D, Sangameswaran L, Segal MR, Hunt CA, Birch R, Anand P. Plasticity of gene expression in injured human dorsal root ganglia revealed by GeneChip oligonucleotide microarrays. J Clin Neurosci 2007; 11:289-99. [PMID: 14975420 DOI: 10.1016/j.jocn.2003.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Accepted: 05/09/2003] [Indexed: 11/29/2022]
Abstract
Root avulsion from the spinal cord occurs in brachial plexus lesions. It is the practice to repair such injuries by transferring an intact neighbouring nerve to the distal stump of the damaged nerve; avulsed dorsal root ganglia (DRG) are removed to enable nerve transfer. Such avulsed adult human cervical DRG ( [Formula: see text] ) obtained at surgery were compared to controls, for the first time, using GeneChip oligonucleotide arrays. We report 91 genes whose expression levels are clearly altered by the injury. This first study provides a global assessment of the molecular events or "gene switches" as a consequence of DRG injuries, as the tissues represent a wide range of surgical delay, from 1 to 100 days. A number of these genes are novel with respect to sensory ganglia, while others are known to be involved in neurotransmission, trophism, cytokine functions, signal transduction, myelination, transcription regulation, and apoptosis. Cluster analysis showed that genes involved in the same functional groups are largely positioned close to each other. This study represents an important step in identifying new genes and molecular mechanisms in human DRG, with potential therapeutic relevance for nerve repair and relief of chronic neuropathic pain.
Collapse
|
45
|
Sarantopoulos CD, McCallum JB, Rigaud M, Fuchs A, Kwok WM, Hogan QH. Opposing effects of spinal nerve ligation on calcium-activated potassium currents in axotomized and adjacent mammalian primary afferent neurons. Brain Res 2007; 1132:84-99. [PMID: 17184741 PMCID: PMC2692681 DOI: 10.1016/j.brainres.2006.11.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 11/09/2006] [Accepted: 11/09/2006] [Indexed: 10/23/2022]
Abstract
UNLABELLED Calcium-activated potassium channels regulate AHP and excitability in neurons. Since we have previously shown that axotomy decreases I(Ca) in DRG neurons, we investigated the association between I(Ca) and K((Ca)) currents in control medium-sized (30-39 microM) neurons, as well as axotomized L5 or adjacent L4 DRG neurons from hyperalgesic rats following L5 SNL. Currents in response to AP waveform voltage commands were recorded first in Tyrode's solution and sequentially after: 1) blocking Na(+) current with NMDG and TTX; 2) addition of K((Ca)) blockers with a combination of apamin 1 microM, iberiotoxin 200 nM, and clotrimazole 500 nM; 3) blocking remaining K(+) current with the addition of 4-AP, TEA-Cl, and glibenclamide; and 4) blocking I(Ca) with cadmium. In separate experiments, currents were evoked (HP -60 mV, 200 ms square command pulses from -100 to +50 mV) while ensuring high levels of activation of I(K(Ca)) by clamping cytosolic Ca(2+) concentration with pipette solution in which Ca(2+) was buffered to 1 microM. This revealed I(K(Ca)) with components sensitive to apamin, clotrimazole and iberiotoxin. SNL decreases total I(K(Ca)) in axotomized (L5) neurons, but increases total I(K(Ca)) in adjacent (L4) DRG neurons. All I(K(Ca)) subtypes are decreased by axotomy, but iberiotoxin-sensitive and clotrimazole-sensitive current densities are increased in adjacent L4 neurons after SNL. In an additional set of experiments we found that small-sized control DRG neurons also expressed iberiotoxin-sensitive currents, which are reduced in both axotomized (L5) and adjacent (L4) neurons. CONCLUSIONS Axotomy decreases I(K(Ca)) due to a direct effect on K((Ca)) channels. Axotomy-induced loss of I(Ca) may further potentiate current reduction. This reduction in I(K(Ca)) may contribute to elevated excitability after axotomy. Adjacent neurons (L4 after SNL) exhibit increased I(K(Ca)) current.
Collapse
MESH Headings
- Animals
- Axotomy
- Calcium/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cell Size/drug effects
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiopathology
- Hyperalgesia/metabolism
- Hyperalgesia/physiopathology
- Ligation
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Organ Culture Techniques
- Patch-Clamp Techniques
- Peripheral Nervous System Diseases/metabolism
- Peripheral Nervous System Diseases/physiopathology
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/metabolism
- Rats
- Rats, Sprague-Dawley
- Sciatic Neuropathy/metabolism
- Sciatic Neuropathy/physiopathology
- Sodium Channel Blockers/pharmacology
Collapse
Affiliation(s)
- Constantine D Sarantopoulos
- Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | | | | | | | | | | |
Collapse
|
46
|
Anand U, Otto WR, Casula MA, Day NC, Davis JB, Bountra C, Birch R, Anand P. The effect of neurotrophic factors on morphology, TRPV1 expression and capsaicin responses of cultured human DRG sensory neurons. Neurosci Lett 2006; 399:51-6. [PMID: 16481104 DOI: 10.1016/j.neulet.2006.01.046] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/15/2006] [Accepted: 01/20/2006] [Indexed: 11/23/2022]
Abstract
We have studied the effect of key neurotrophic factors (NTFs) on morphology, levels of the vanilloid receptor-1 (TRPV1) and responses to capsaicin in adult human sensory neurons in vitro. Avulsed dorsal root ganglia (DRG, n = 5) were cultured with or without a combination of nerve growth factor (NGF), glial cell (line)-derived growth factor (GDNF) and neurotrophin3 (NT3) for 5 days. In the absence of NTFs, the diameter of neurons ranged from 20 to 100 microm (mean 42 +/- 4 microm). Adding NTFs caused a significant increase in neuronal sizes, up to 120 microm (mean diameter 62 +/- 5 microm, P < 0.01, t-test), an overall 35% increase of TRPV1-positive neurons (P < 0.003), and notably of large TRPV1-positive neurons > 80 microm (P < 0.05). Responses to capsaicin were significantly enhanced with calcium ratiometry (P < 0.0001). Short duration (1h) exposure of dissociated sensory neurons to NTFs increased numbers of TRPV1-positive neurons, but not of TRPV3, Nav 1.8 and IK1 and the morphological size-distribution remained similar to intact post-mortem DRG neurons. NTFs thus increase size, elevate TRPV1 levels and enhance capsaicin responses in cultured human DRG neurons; these changes may relate to pathophysiology in disease states, and provide an in vitro model to study novel analgesics.
Collapse
Affiliation(s)
- U Anand
- Peripheral Neuropathy Unit, Imperial College, Area A, Ground Floor, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
| | | | | | | | | | | | | | | |
Collapse
|
47
|
McNeish AJ, Sandow SL, Neylon CB, Chen MX, Dora KA, Garland CJ. Evidence for involvement of both IKCa and SKCa channels in hyperpolarizing responses of the rat middle cerebral artery. Stroke 2006; 37:1277-82. [PMID: 16556879 DOI: 10.1161/01.str.0000217307.71231.43] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Endothelium-derived hyperpolarizing factor responses in the rat middle cerebral artery are blocked by inhibiting IKCa channels alone, contrasting with peripheral vessels where block of both IKCa and SKCa is required. As the contribution of IKCa and SKCa to endothelium-dependent hyperpolarization differs in peripheral arteries, depending on the level of arterial constriction, we investigated the possibility that SKCa might contribute to equivalent hyperpolarization in cerebral arteries under certain conditions. METHODS Rat middle cerebral arteries (approximately 175 microm) were mounted in a wire myograph. The effect of KCa channel blockers on endothelium-dependent responses to the protease-activated receptor 2 agonist, SLIGRL (20 micromol/L), were then assessed as simultaneous changes in tension and membrane potential. These data were correlated with the distribution of arterial KCa channels revealed with immunohistochemistry. RESULTS SLIGRL hyperpolarized and relaxed cerebral arteries undergoing variable levels of stretch-induced tone. The relaxation was unaffected by specific inhibitors of IKCa (TRAM-34, 1 micromol/L) or SKCa (apamin, 50 nmol/L) alone or in combination. In contrast, the associated smooth-muscle hyperpolarization was inhibited, but only with these blockers in combination. Blocking nitric oxide synthase (NOS) or guanylyl cyclase evoked smooth-muscle depolarization and constriction, with both hyperpolarization and relaxation to SLIGRL being abolished by TRAM-34 alone, whereas apamin had no effect. Immunolabeling showed SKCa and IKCa within the endothelium. CONCLUSIONS In the absence of NO, IKCa underpins endothelium-dependent hyperpolarization and relaxation in cerebral arteries. However, when NOS is active SKCa contributes to hyperpolarization, whatever the extent of background contraction. These changes may have relevance in vascular disease states where NO release is compromised and when the levels of SKCa expression may be altered.
Collapse
Affiliation(s)
- Alister J McNeish
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | | | | | | | | | | |
Collapse
|
48
|
Konrad C, Schmelz M. [Mechanisms in the development of pain. Key issue in the periphery]. Internist (Berl) 2006; 46:1115-21. [PMID: 16086139 DOI: 10.1007/s00108-005-1476-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The interaction between neurons, tissue cells and inflammatory cells is of major importance for the development of pain in the periphery. In this interaction a variety of inhibitory and activating circuits has been identified in recent years. In addition to the receptors for classical inflammatory mediators on the sensory terminals like bradykinin, axonal ion channels have been identified as major modulators of pain and sensitization apart from their traditional role in conduction of action potentials. Sensitization of spinal nociceptive processing is crucial for the expansion of pain beyond the initially injured site and contributes to chronic pain. Learning processes and extinction of aversive memory are of major importance for the development, but also the therapy of chronic pain states.
Collapse
Affiliation(s)
- C Konrad
- Klinik für Anästhesiologie und Operative Intensivmedizin, Fakultät Klinische Medizin Mannheim der Universität Heidelberg.
| | | |
Collapse
|
49
|
Bahia PK, Suzuki R, Benton DCH, Jowett AJ, Chen MX, Trezise DJ, Dickenson AH, Moss GWJ. A functional role for small-conductance calcium-activated potassium channels in sensory pathways including nociceptive processes. J Neurosci 2006; 25:3489-98. [PMID: 15814779 PMCID: PMC6725366 DOI: 10.1523/jneurosci.0597-05.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We investigated the role of small-conductance calcium-activated potassium (SK) and intermediate-conductance calcium-activated potassium channels in modulating sensory transmission from peripheral afferents into the rat spinal cord. Subunit-specific antibodies reveal high levels of SK3 immunoreactivity in laminas I, II, and III of the spinal cord. Among dorsal root ganglion neurons, both peripherin-positive (C-type) and peripherin-negative (A-type) cells show intense SK3 immunoreactivity. Furthermore, dorsal root-stimulated sensory responses recorded in vitro are inhibited when SK channel activity is increased with 1-ethyl-2-benzimidazolinone (1-EBIO). In vivo electrophysiological recordings show that neuronal responses to naturally evoked nociceptive and nonnociceptive stimuli increase after application of the selective SK channel blocker 8,14-diaza-1,7(1,4)-diquinolinacyclotetradecaphanedium di-trifluoroacetate (UCL 1848), indicating that SK channels are normally active in moderating afferent input. Conversely, neuronal responses evoked by mechanical stimuli are inhibited when SK channel activity is increased with 1-EBIO. These effects are reversed by the subsequent application of UCL 1848. Our data demonstrate that SK channels have an important role in controlling sensory input into the spinal cord.
Collapse
Affiliation(s)
- Parmvir K Bahia
- Department of Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
50
|
|