1
|
George DS, Jayaraj ND, Pacifico P, Ren D, Sriram N, Miller RE, Malfait AM, Miller RJ, Menichella DM. The Mas-related G protein-coupled receptor d (Mrgprd) mediates pain hypersensitivity in painful diabetic neuropathy. Pain 2024; 165:1154-1168. [PMID: 38147415 PMCID: PMC11017747 DOI: 10.1097/j.pain.0000000000003120] [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: 04/18/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 12/28/2023]
Abstract
ABSTRACT Painful diabetic neuropathy (PDN) is one of the most common and intractable complications of diabetes. Painful diabetic neuropathy is characterized by neuropathic pain accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability, axonal degeneration, and changes in cutaneous innervation. However, the complete molecular profile underlying the hyperexcitable cellular phenotype of DRG nociceptors in PDN has not been elucidated. This gap in our knowledge is a critical barrier to developing effective, mechanism-based, and disease-modifying therapeutic approaches that are urgently needed to relieve the symptoms of PDN. Using single-cell RNA sequencing of DRGs, we demonstrated an increased expression of the Mas-related G protein-coupled receptor d (Mrgprd) in a subpopulation of DRG neurons in the well-established high-fat diet (HFD) mouse model of PDN. Importantly, limiting Mrgprd signaling reversed mechanical allodynia in the HFD mouse model of PDN. Furthermore, in vivo calcium imaging allowed us to demonstrate that activation of Mrgprd-positive cutaneous afferents that persist in diabetic mice skin resulted in an increased intracellular calcium influx into DRG nociceptors that we assess in vivo as a readout of nociceptors hyperexcitability. Taken together, our data highlight a key role of Mrgprd-mediated DRG neuron excitability in the generation and maintenance of neuropathic pain in a mouse model of PDN. Hence, we propose Mrgprd as a promising and accessible target for developing effective therapeutics currently unavailable for treating neuropathic pain in PDN.
Collapse
Affiliation(s)
| | | | | | - Dongjun Ren
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | | | - Rachel E. Miller
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Anne-Marie Malfait
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Richard J. Miller
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniela Maria Menichella
- Departments of Neurology and
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| |
Collapse
|
2
|
Xie YF, Yang J, Ratté S, Prescott SA. Similar excitability through different sodium channels and implications for the analgesic efficacy of selective drugs. eLife 2024; 12:RP90960. [PMID: 38687187 PMCID: PMC11060714 DOI: 10.7554/elife.90960] [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] [Indexed: 05/02/2024] Open
Abstract
Nociceptive sensory neurons convey pain-related signals to the CNS using action potentials. Loss-of-function mutations in the voltage-gated sodium channel NaV1.7 cause insensitivity to pain (presumably by reducing nociceptor excitability) but clinical trials seeking to treat pain by inhibiting NaV1.7 pharmacologically have struggled. This may reflect the variable contribution of NaV1.7 to nociceptor excitability. Contrary to claims that NaV1.7 is necessary for nociceptors to initiate action potentials, we show that nociceptors can achieve similar excitability using different combinations of NaV1.3, NaV1.7, and NaV1.8. Selectively blocking one of those NaV subtypes reduces nociceptor excitability only if the other subtypes are weakly expressed. For example, excitability relies on NaV1.8 in acutely dissociated nociceptors but responsibility shifts to NaV1.7 and NaV1.3 by the fourth day in culture. A similar shift in NaV dependence occurs in vivo after inflammation, impacting ability of the NaV1.7-selective inhibitor PF-05089771 to reduce pain in behavioral tests. Flexible use of different NaV subtypes exemplifies degeneracy - achieving similar function using different components - and compromises reliable modulation of nociceptor excitability by subtype-selective inhibitors. Identifying the dominant NaV subtype to predict drug efficacy is not trivial. Degeneracy at the cellular level must be considered when choosing drug targets at the molecular level.
Collapse
Affiliation(s)
- Yu-Feng Xie
- Neurosciences and Mental Health, The Hospital for Sick ChildrenTorontoCanada
| | - Jane Yang
- Neurosciences and Mental Health, The Hospital for Sick ChildrenTorontoCanada
- Institute of Biomedical Engineering, University of TorontoTorontoCanada
| | - Stéphanie Ratté
- Neurosciences and Mental Health, The Hospital for Sick ChildrenTorontoCanada
| | - Steven A Prescott
- Neurosciences and Mental Health, The Hospital for Sick ChildrenTorontoCanada
- Institute of Biomedical Engineering, University of TorontoTorontoCanada
- Department of Physiology, University of TorontoTorontoCanada
| |
Collapse
|
3
|
Jang K, Garraway SM. A review of dorsal root ganglia and primary sensory neuron plasticity mediating inflammatory and chronic neuropathic pain. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2024; 15:100151. [PMID: 38314104 PMCID: PMC10837099 DOI: 10.1016/j.ynpai.2024.100151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/04/2024] [Accepted: 01/19/2024] [Indexed: 02/06/2024]
Abstract
Pain is a sensory state resulting from complex integration of peripheral nociceptive inputs and central processing. Pain consists of adaptive pain that is acute and beneficial for healing and maladaptive pain that is often persistent and pathological. Pain is indeed heterogeneous, and can be expressed as nociceptive, inflammatory, or neuropathic in nature. Neuropathic pain is an example of maladaptive pain that occurs after spinal cord injury (SCI), which triggers a wide range of neural plasticity. The nociceptive processing that underlies pain hypersensitivity is well-studied in the spinal cord. However, recent investigations show maladaptive plasticity that leads to pain, including neuropathic pain after SCI, also exists at peripheral sites, such as the dorsal root ganglia (DRG), which contains the cell bodies of sensory neurons. This review discusses the important role DRGs play in nociceptive processing that underlies inflammatory and neuropathic pain. Specifically, it highlights nociceptor hyperexcitability as critical to increased pain states. Furthermore, it reviews prior literature on glutamate and glutamate receptors, voltage-gated sodium channels (VGSC), and brain-derived neurotrophic factor (BDNF) signaling in the DRG as important contributors to inflammatory and neuropathic pain. We previously reviewed BDNF's role as a bidirectional neuromodulator of spinal plasticity. Here, we shift focus to the periphery and discuss BDNF-TrkB expression on nociceptors, non-nociceptor sensory neurons, and non-neuronal cells in the periphery as a potential contributor to induction and persistence of pain after SCI. Overall, this review presents a comprehensive evaluation of large bodies of work that individually focus on pain, DRG, BDNF, and SCI, to understand their interaction in nociceptive processing.
Collapse
Affiliation(s)
- Kyeongran Jang
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
| | - Sandra M. Garraway
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
| |
Collapse
|
4
|
Pacifico P, Coy-Dibley JS, Miller RJ, Menichella DM. Peripheral mechanisms of peripheral neuropathic pain. Front Mol Neurosci 2023; 16:1252442. [PMID: 37781093 PMCID: PMC10537945 DOI: 10.3389/fnmol.2023.1252442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 08/14/2023] [Indexed: 10/03/2023] Open
Abstract
Peripheral neuropathic pain (PNP), neuropathic pain that arises from a damage or disease affecting the peripheral nervous system, is associated with an extremely large disease burden, and there is an increasing and urgent need for new therapies for treating this disorder. In this review we have highlighted therapeutic targets that may be translated into disease modifying therapies for PNP associated with peripheral neuropathy. We have also discussed how genetic studies and novel technologies, such as optogenetics, chemogenetics and single-cell RNA-sequencing, have been increasingly successful in revealing novel mechanisms underlying PNP. Additionally, consideration of the role of non-neuronal cells and communication between the skin and sensory afferents is presented to highlight the potential use of drug treatment that could be applied topically, bypassing drug side effects. We conclude by discussing the current difficulties to the development of effective new therapies and, most importantly, how we might improve the translation of targets for peripheral neuropathic pain identified from studies in animal models to the clinic.
Collapse
Affiliation(s)
- Paola Pacifico
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - James S. Coy-Dibley
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Richard J. Miller
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniela M. Menichella
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| |
Collapse
|
5
|
Liu H, Lauzadis J, Gunaratna K, Sipple E, Kaczocha M, Puopolo M. Inhibition of T-Type Calcium Channels With TTA-P2 Reduces Chronic Neuropathic Pain Following Spinal Cord Injury in Rats. THE JOURNAL OF PAIN 2023; 24:1681-1695. [PMID: 37169156 DOI: 10.1016/j.jpain.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 04/03/2023] [Accepted: 05/02/2023] [Indexed: 05/13/2023]
Abstract
Spinal cord injury (SCI)-induced neuropathic pain (SCI-NP) develops in up to 60 to 70% of people affected by traumatic SCI, leading to a major decline in quality of life and increased risk for depression, anxiety, and addiction. Gabapentin and pregabalin, together with antidepressant drugs, are commonly prescribed to treat SCI-NP, but their efficacy is unsatisfactory. The limited efficacy of current pharmacological treatments for SCI-NP likely reflects our limited knowledge of the underlying mechanism(s) responsible for driving the maintenance of SCI-NP. The leading hypothesis in the field supports a major role for spontaneously active injured nociceptors in driving the maintenance of SCI-NP. Recent data from our laboratory provided additional support for this hypothesis and identified the T-type calcium channels as key players in driving the spontaneous activity of SCI-nociceptors, thus providing a rational pharmacological target to treat SCI-NP. To test whether T-type calcium channels contribute to the maintenance of SCI-NP, male and female SCI and sham rats were treated with TTA-P2 (a blocker of T-type calcium channels) to determine its effects on mechanical hypersensitivity (as measured with the von Frey filaments) and spontaneous ongoing pain (as measured with the conditioned place preference paradigm), and compared them to the effects of gabapentin, a blocker of high voltage-activated calcium channels. We found that both TTA-P2 and gabapentin reduced mechanical hypersensitivity in male and females SCI rats, but surprisingly only TTA-P2 reduced spontaneous ongoing pain in male SCI rats. PERSPECTIVES: SCI-induced neuropathic pain, and in particular the spontaneous ongoing pain component, is notoriously very difficult to treat. Our data provide evidence that inhibition of T-type calcium channels reduces spontaneous ongoing pain in SCI rats, supporting a clinically relevant role for T-type channels in the maintenance of SCI-induced neuropathic pain.
Collapse
Affiliation(s)
- Huilin Liu
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Justas Lauzadis
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Kavindu Gunaratna
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Erin Sipple
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Martin Kaczocha
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York.
| |
Collapse
|
6
|
Yamada K, Aota Y, Saito T, Inaba Y. Correlation between leg pain at rest and spinal nerve edema in symptomatic lumbar foraminal stenosis. Orthop Traumatol Surg Res 2023; 109:103119. [PMID: 34666199 DOI: 10.1016/j.otsr.2021.103119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/09/2021] [Accepted: 06/02/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND Previous studies reported that spinal nerve edema on magnetic resonance myelography (MRM) and leg pain at rest were specifically observed in symptomatic lumbar foraminal stenosis patients. However, the correlation between leg pain at rest and spinal nerve edema in symptomatic foraminal stenosis has not been reported. HYPOTHESIS The purpose of this prospective study is to reveal a correlation between leg pain at rest and spinal nerve edema focusing on the pathophysiology of symptomatic foraminal stenosis. PATIENTS AND METHODS Clinical findings and MRM findings were surveyed among 30 patients with symptomatic foraminal stenosis diagnosed by MR imaging (MRI) and selective nerve root block. Comparisons of patient characteristics and clinical findings between the prevalence and absence groups of spinal nerve edema on MRM were analyzed. A correlation between the visual analogue scale (VAS) for leg pain at rest and the spinal edema ratio calculated as maximum intensity value of the affected spinal nerve/maximum intensity value of the asymptomatic side from region of interest (ROI) made on MRM was evaluated. RESULTS Twenty symptomatic foraminal stenosis cases (67%) showed the affected spinal nerve edema on MRM. The prevalence and VAS of leg pain at rest were significantly higher in the presence of spinal nerve edema group (95% and 67.0±36.4, respectively). The correlation coefficient between the VAS for leg pain at rest (53.0±33.6) and the spinal nerve edema ratio (1.3±0.3) was 0.647 (p<0.01). DISCUSSION Our study revealed the substantial correlation found between the spinal nerve edema ratio on MRM and the VAS for leg pain at rest in symptomatic foraminal stenosis. The correlation between spinal nerve edema and leg pain at rest has potential to clarify the pathology of symptomatic foraminal stenosis. LEVEL OF EVIDENCE IV.
Collapse
Affiliation(s)
- Katsutaka Yamada
- Department of Orthopaedic Surgery, Yokohama Brain and Spine Center, Yokohama, Japan.
| | - Yoichi Aota
- Department of Orthopaedic Surgery, Yokohama Brain and Spine Center, Yokohama, Japan
| | - Tomoyuki Saito
- Department of Orthopaedic Surgery, Yokohama Brain and Spine Center, Yokohama, Japan
| | - Yutaka Inaba
- Department of Orthopaedic Surgery, Yokohama City University, Yokohama, Japan
| |
Collapse
|
7
|
Zhu T, Wei S, Wang Y. Post-Inhibitory Rebound Firing of Dorsal Root Ganglia Neurons. J Pain Res 2022; 15:2029-2040. [PMID: 35923842 PMCID: PMC9342929 DOI: 10.2147/jpr.s370335] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/02/2022] [Indexed: 01/06/2023] Open
Abstract
Background In the central nervous system, post-inhibitory rebound firing (RF) may mediate overactivity of neurons under pathophysiological condition. RF is also observed in dorsal root ganglion (IRA) neurons. However, the functional significance of RF in primary sensory neurons has remained unknown. After peripheral sensory nerve/neuron injury, DRG neurons exhibit hyperexcitability. Therefore, RF may play a role in neuropathic pain. Methods Chronic compression of DRG (CCD) is used as a neuropathic pain model. Rats were divided into 2 groups: Sham and CCD groups. Patch clamp was performed on the whole DRG and cultured DRG neurons to record RF and T-type Ca2+ currents. The blocker of T-type Ca2+ channels, NiCl2, was applied to DRG neurons. Results Rebound neurons were more excitable than non-rebound neurons. And they discharged RF with prominent after depolarizing potentials, which were blocked by NiCl2. After DRG injury, the proportion of rebound neurons augmented, and rebound neurons’ excitability increased. Meanwhile, the steady-state activation curve of T-type Ca2+ channels was shifted toward the left. Conclusion RF may be related to highly excitable neurons and sensitive to both depolarization and hyperpolarization. T-type Ca2+ channels were critical to RF, potentially enhancing the spontaneous firing of rebound neurons in response to resting membrane potential fluctuations.
Collapse
Affiliation(s)
- Tong Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Clinical Experimental Center, Xi’an International Medical Center Hospital, Xi’an, Shaanxi, 710100, People’s Republic of China
| | - Siqi Wei
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
| | - Yuying Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Institute of Neuroscience, Translational Medicine Institute, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Key Laboratory of Environment and Genes Related to Diseases (Xi’an Jiaotong University), Ministry of Education, Xi’an, People’s Republic of China
- Correspondence: Yuying Wang, Email
| |
Collapse
|
8
|
Zhu T, Wang Y. T-type Ca 2+ channels play a dual role in modulating the excitability of dorsal root ganglia neurons. Mol Pain 2022; 18:17448069221132224. [PMID: 36163701 PMCID: PMC9536108 DOI: 10.1177/17448069221132224] [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] [Indexed: 11/17/2022] Open
Abstract
A subgroup of low-threshold dorsal root ganglia (DRG) neurons discharge action potentials (APs) with an afterdepolarizing potential (ADP). The ADP is formed by T-type Ca2+ currents. It is known that T-type Ca2+ currents contribute to neuropathic pain. However, the change in ADP-firing of injured DRG neurons has not been widely studied yet. Here we applied patch clamp to record ADP-firing and T-type Ca2+ currents in intact and chronically compressed DRG (CCD) neurons and examined T-type Ca2+ channel proteins expression with western blotting. After CCD injury, the incidences of both ADP firing and non-ADP burst firing increased, and T-type Ca2+ channels contributed to both of these firing patterns. The neurons discharging large-amplitude-ADP firing were TTX-insensitive, implying that high-density T-type Ca2+ channels might cooperate with TTX-insensitive Na+ channels to reduce the AP threshold. By contrast, the neurons displaying non-ADP burst firing were TTX-sensitive, implying that low density T-type Ca2+ channels may cooperate with TTX-sensitive Na+ channels to increase AP number. In DRG neurons, T-type Ca2+ currents density varied widely, ranging between 100 pA/pF and 5 pA/pF. After injury, the proportion of DRG neurons with large T-type Ca2+ currents increased in parallel with the increase in the incidence of large-amplitude-ADP firing. And in addition to Cav3.2, Cav3.3 channels are also likely to contribute to low-threshold firing. The data revealed that T-type Ca2+ channels may play a dual role in modulating the injured neurons' high excitability through a cooperative process with Na+ channels, thereby contributing to neuropathic pain.
Collapse
Affiliation(s)
- Tong Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Clinical Experimental Center, Xi'an International Medical Center Hospital, Xi'an, China
| | - Yuying Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, 12480Xi'an Jiaotong University, Xi'an, China.,Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China
| |
Collapse
|
9
|
George DS, Hackelberg S, Jayaraj ND, Ren D, Edassery SL, Rathwell CA, Miller RE, Malfait AM, Savas JN, Miller RJ, Menichella DM. Mitochondrial calcium uniporter deletion prevents painful diabetic neuropathy by restoring mitochondrial morphology and dynamics. Pain 2022; 163:560-578. [PMID: 34232927 PMCID: PMC8720329 DOI: 10.1097/j.pain.0000000000002391] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 05/25/2021] [Accepted: 06/18/2021] [Indexed: 01/11/2023]
Abstract
ABSTRACT Painful diabetic neuropathy (PDN) is an intractable complication affecting 25% of diabetic patients. Painful diabetic neuropathy is characterized by neuropathic pain accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability, resulting in calcium overload, axonal degeneration, and loss of cutaneous innervation. The molecular pathways underlying these effects are unknown. Using high-throughput and deep-proteome profiling, we found that mitochondrial fission proteins were elevated in DRG neurons from mice with PDN induced by a high-fat diet (HFD). In vivo calcium imaging revealed increased calcium signaling in DRG nociceptors from mice with PDN. Furthermore, using electron microscopy, we showed that mitochondria in DRG nociceptors had fragmented morphology as early as 2 weeks after starting HFD, preceding the onset of mechanical allodynia and small-fiber degeneration. Moreover, preventing calcium entry into the mitochondria, by selectively deleting the mitochondrial calcium uniporter from these neurons, restored normal mitochondrial morphology, prevented axonal degeneration, and reversed mechanical allodynia in the HFD mouse model of PDN. These studies suggest a molecular cascade linking neuropathic pain to axonal degeneration in PDN. In particular, nociceptor hyperexcitability and the associated increased intracellular calcium concentrations could lead to excessive calcium entry into mitochondria mediated by the mitochondrial calcium uniporter, resulting in increased calcium-dependent mitochondrial fission and ultimately contributing to small-fiber degeneration and neuropathic pain in PDN. Hence, we propose that targeting calcium entry into nociceptor mitochondria may represent a promising effective and disease-modifying therapeutic approach for this currently intractable and widespread affliction. Moreover, these results are likely to inform studies of other neurodegenerative disease involving similar underlying events.
Collapse
Affiliation(s)
| | | | | | - Dongjun Ren
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | | | - Craig A. Rathwell
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Rachel E. Miller
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Anne-Marie Malfait
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | | | - Richard J. Miller
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | | |
Collapse
|
10
|
Vuka I, Marciuš T, Kovačić D, Šarolić A, Puljak L, Sapunar D. Implantable, Programmable, and Wireless Device for Electrical Stimulation of the Dorsal Root Ganglion in Freely-Moving Rats: A Proof of Concept Study. J Pain Res 2021; 14:3759-3772. [PMID: 34916842 PMCID: PMC8668248 DOI: 10.2147/jpr.s332438] [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: 08/03/2021] [Accepted: 11/23/2021] [Indexed: 11/23/2022] Open
Abstract
Objective This was a proof of concept study, based on systematic reviews of the efficacy and safety of the dorsal root ganglion (DRG) stimulation. The main objective was to develop an implantable, programmable, and wireless device for electrical stimulation of DRG and a methodology that can be used in translational research, especially to understand the mechanism of neuromodulation and to test new treatment modalities in animal models of pain. Methods We developed and tested a stimulator that uses a battery-powered microelectronic circuit, to generate constant current square biphasic or monophasic pulsed waveform of variable amplitudes and duration. It is controlled by software and an external controller that allows radio frequency communication with the stimulator. The stimulator was implanted in Sprague–Dawley (SD) rats. The lead was positioned at the L5 DRG level, while the stimulator was placed in the skin pocket at the ipsilateral side. Forty-five animals were used and divided into six groups: spinal nerve ligation (SNL), chronic compression injury of the DRG (CCD), SNL + active DRG stimulation, intact control group, group with the implanted sham stimulator, and sham lead. Behavioral testing was performed on the day preceding surgery and three times postoperatively (1st, 3rd, and 7th day). Results In animals with SNL, neurostimulation reduced pain-related behavior, tested with pinprick hyperalgesia, pinprick withdrawal test, and cold test, while the leads per se did not cause DRG compression. The rats well tolerated the stimulator. It did not hinder animal movement, and it enabled the animals to be housed under regular conditions. Conclusion A proof-of-concept experiment with our stimulator verified the usability of the device. The stimulator enables a wide range of research applications from adjusting stimulation parameters for different pain conditions, studying new stimulation methods with different frequencies and waveforms to obtain knowledge about analgesic mechanisms of DRG stimulation.
Collapse
Affiliation(s)
- Ivana Vuka
- Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia
| | - Tihana Marciuš
- Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia
| | - Damir Kovačić
- Laboratory for Biophysics and Medical Neuroelectronics, University of Split Faculty of Science, Split, Croatia
| | - Antonio Šarolić
- Laboratory for Applied Electromagnetics (EMLab), FESB, University of Split, Split, Croatia
| | - Livia Puljak
- Centre for Evidence-Based Medicine and Health Care, Catholic University of Croatia, Zagreb, Croatia
| | - Damir Sapunar
- Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia
| |
Collapse
|
11
|
Schiel KA. A beneficial role for elevated extracellular glutamate in Amyotrophic Lateral Sclerosis and cerebral ischemia. Bioessays 2021; 43:e2100127. [PMID: 34585427 DOI: 10.1002/bies.202100127] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 11/06/2022]
Abstract
This hypothesis proposes that increased extracellular glutamate in Amyotrophic Lateral Sclerosis (ALS) and cerebral ischemia, currently viewed as a trigger for excitotoxicity, is actually beneficial as it stimulates the utilization of glutamate as metabolic fuel. Renewed appreciation of glutamate oxidation by ischemic neurons has raised questions regarding the role of extracellular glutamate in ischemia. Is it detrimental, as suggested by excitotoxicity in early in vitro studies, or beneficial, as suggested by its oxidation in later in vivo studies? The answer may depend on the activity of N-methyl-D-aspartate (NMDA) glutamate receptors. Early in vitro procedures co-activated NMDA receptors (NMDARs) containing 2A (GluN2A) and 2B (GluN2B) subunits, an event now believed to trigger excitotoxicity; however, during in vivo ischemia D-serine and zinc molecules are released and these ensure only GluN2B receptors are stimulated. This not only prevents excitotoxicity but also initiates signaling cascades that allow ischemic neurons to import and oxidize glutamate.
Collapse
|
12
|
Raja SN, Ringkamp M, Guan Y, Campbell JN. John J. Bonica Award Lecture: Peripheral neuronal hyperexcitability: the "low-hanging" target for safe therapeutic strategies in neuropathic pain. Pain 2021; 161 Suppl 1:S14-S26. [PMID: 33090736 DOI: 10.1097/j.pain.0000000000001838] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | - Matthias Ringkamp
- Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Yun Guan
- Departments of Anesthesiology and Critical Care Medicine and.,Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - James N Campbell
- Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| |
Collapse
|
13
|
Uranbileg B, Ito N, Kurano M, Kano K, Uchida K, Sumitani M, Aoki J, Yatomi Y. Inhibition of autotaxin activity ameliorates neuropathic pain derived from lumbar spinal canal stenosis. Sci Rep 2021; 11:3984. [PMID: 33597645 PMCID: PMC7889906 DOI: 10.1038/s41598-021-83569-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
Lumbar spinal canal stenosis (LSS) or mechanical compression of dorsal root ganglion (DRG) is one of the causes of low back pain and neuropathic pain (NP). Lysophosphatidic acid (LPA) is a potent bioactive lipid mediator that is produced mainly from lysophosphatidylcholine (LPC) via autotaxin (ATX) and is known to induce NP via LPA1 receptor signaling in mice. Recently, we demonstrated that LPC and LPA were higher in cerebrospinal fluid (CSF) of patients with LSS. Based on the possible potential efficacy of the ATX inhibitor for NP treatment, we used an NP model with compression of DRG (CD model) and investigated LPA dynamics and whether ATX inhibition could ameliorate NP symptoms, using an orally available ATX inhibitor (ONO-8430506) at a dose of 30 mg/kg. In CD model, we observed increased LPC and LPA levels in CSF, and decreased threshold of the pain which were ameliorated by oral administration of the ATX inhibitor with decreased microglia and astrocyte populations at the site of the spinal dorsal horn projecting from injured DRG. These results suggested possible efficacy of ATX inhibitor for the treatment of NP caused by spinal nerve root compression and involvement of the ATX-LPA axis in the mechanism of NP induction.
Collapse
Affiliation(s)
- Baasanjav Uranbileg
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Nobuko Ito
- Department of Anesthesiology and Pain Relief Center, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
| | - Makoto Kurano
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Kuniyuki Kano
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kanji Uchida
- Department of Anesthesiology and Pain Relief Center, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Masahiko Sumitani
- Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Junken Aoki
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yutaka Yatomi
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
14
|
Wang T, Tao J, Fang Y, Ma C. The role of pruriceptors in enhancing sensitivity to pruritogens in a murine chronic compression model of dorsal root ganglion. Mol Brain 2021; 14:15. [PMID: 33468207 PMCID: PMC7814616 DOI: 10.1186/s13041-021-00730-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/04/2021] [Indexed: 11/30/2022] Open
Abstract
Chronic pruritus is a symptom that commonly observed in neurological diseases. It has been hypothesized that the chronic pruritus may result from sensitization of itch-signaling pathways but the mechanisms remain obscure. In this study, we established a mouse model of chronic compression of dorsal root ganglion (CCD) and injected various pruritogenic and algogenic agents intradermally to the calf skin ipsilateral to the compressed dorsal root ganglion (DRG). Compared to the naïve mice, a significant increase in itch-related behaviors was observed in the CCD mice after the injection of pruritogens including histamine and BAM8-22, but not after the injection of capsaicin, although all the above agents evoked enhanced pain-related behaviors toward the injected site. In addition, we investigated if pruritogen-evoked activities of DRG neurons were enhanced in this model. In vivo calcium imaging revealed that compressed DRG neurons exhibited enhanced responses to histamine and BAM8-22. Immunoflorescent staining also showed that the histamine receptor H1 and the capsaicin receptor TRPV1 were significantly upregulated in DRG neurons. Our findings indicated that the sensitization of primary pruriceptive neurons may underlie the enhanced itch sensation after chronic compression of DRG in the mice, and may play a role in chronic pruritus in neurological diseases.
Collapse
MESH Headings
- Animals
- Calcium/metabolism
- Capsaicin/adverse effects
- Cattle
- Chronic Disease
- Disease Models, Animal
- Ganglia, Spinal/diagnostic imaging
- Ganglia, Spinal/pathology
- Histamine/adverse effects
- Male
- Mice, Inbred C57BL
- Mice, Transgenic
- Nerve Compression Syndromes/complications
- Nerve Compression Syndromes/metabolism
- Nerve Compression Syndromes/pathology
- Neurons/metabolism
- Pain/pathology
- Peptide Fragments/adverse effects
- Pruritus/metabolism
- Pruritus/pathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Histamine H1/metabolism
- Receptors, Histamine H4/metabolism
- TRPV Cation Channels/metabolism
- Up-Regulation/genetics
- Mice
Collapse
Affiliation(s)
- Tao Wang
- Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100005, China
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- Joint Laboratory of Anesthesia and Pain, Peking Union Medical College, Beijing, 100730, China
| | - Jin Tao
- Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100005, China
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- Joint Laboratory of Anesthesia and Pain, Peking Union Medical College, Beijing, 100730, China
| | - Yehong Fang
- Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100005, China
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- Joint Laboratory of Anesthesia and Pain, Peking Union Medical College, Beijing, 100730, China
| | - Chao Ma
- Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100005, China.
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
- Joint Laboratory of Anesthesia and Pain, Peking Union Medical College, Beijing, 100730, China.
| |
Collapse
|
15
|
Local Sympathectomy Promotes Anti-inflammatory Responses and Relief of Paclitaxel-induced Mechanical and Cold Allodynia in Mice. Anesthesiology 2020; 132:1540-1553. [PMID: 32404819 DOI: 10.1097/aln.0000000000003241] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Patients undergoing cancer treatment often experience chemotherapy-induced neuropathic pain at their extremities, for which there is no U.S. Food and Drug Administration-approved drug. The authors hypothesized that local sympathetic blockade, which is used in the clinic to treat various pain conditions, can also be effective to treat chemotherapy-induced neuropathic pain. METHODS A local sympathectomy (i.e., cutting the ipsilateral gray rami entering the spinal nerves near the L3 and L4 dorsal root ganglia) was performed in mice receiving intraperitoneal injections every other day of the chemotherapeutic drug paclitaxel. Sympathectomy effects were then assessed in chemotherapy-induced pain-like behaviors (i.e., mechanical and cold allodynia) and neuroimmune and electrophysiologic responses. RESULTS Local microsympathectomy produced a fast recovery from mechanical allodynia (mean ± SD: sympathectomy vs. sham at day 5, 1.07 ± 0.34 g vs. 0.51 ± 0.17g, n = 5, P = 0.030 in male mice, and 1.08 ± 0.28 g vs. 0.62 ± 0.16 g, n = 5, P = 0.036 in female mice) and prevented the development of cold allodynia in both male and female mice after paclitaxel. Mechanistically, microsympathectomy induced transcriptional increases in dorsal root ganglia of macrophage markers and anti-inflammatory cytokines, such as the transforming growth factor-β. Accordingly, depletion of monocytes/macrophages and blockade of transforming growth factor-β signaling reversed the relief of mechanical allodynia by microsympathectomy. In particular, exogenous transforming growth factor-β was sufficient to relieve mechanical allodynia after paclitaxel (transforming growth factor-β 100 ng/site vs. vehicle at 3 h, 1.21 ± 0.34g vs. 0.53 ± 0.14 g, n = 5, P = 0.001 in male mice), and transforming growth factor-β signaling regulated neuronal activity in dorsal root ganglia. CONCLUSIONS Local sympathetic nerves control the progression of immune responses in dorsal root ganglia and pain-like behaviors in mice after paclitaxel, raising the possibility that clinical strategies already in use for local sympathetic blockade may also offer an effective treatment for patients experiencing chemotherapy-induced neuropathic pain.
Collapse
|
16
|
The emergence of animal models of chronic pain and logistical and methodological issues concerning their use. J Neural Transm (Vienna) 2019; 127:393-406. [DOI: 10.1007/s00702-019-02103-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 11/07/2019] [Indexed: 12/12/2022]
|
17
|
Shinoda M, Fukuoka T, Takeda M, Iwata K, Noguchi K. Spinal glial cell line-derived neurotrophic factor infusion reverses reduction of Kv4.1-mediated A-type potassium currents of injured myelinated primary afferent neurons in a neuropathic pain model. Mol Pain 2019; 15:1744806919841196. [PMID: 30868936 PMCID: PMC6463340 DOI: 10.1177/1744806919841196] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
High frequency spontaneous activity in injured primary afferents has been proposed as a pathological mechanism of neuropathic pain following nerve injury. Although spinal infusion of glial cell line-derived neurotrophic factor reduces the activity of injured myelinated A-fiber neurons after fifth lumbar (L5) spinal nerve ligation in rats, the implicated molecular mechanism remains undetermined. The fast-inactivating transient A-type potassium current (IA) is an important determinant of neuronal excitability, and five voltage-gated potassium channel (Kv) alpha-subunits, Kv1.4, Kv3.4, Kv4.1, Kv4.2, and Kv4.3, display IA in heterologous expression systems. Here, we examined the effect of spinal glial cell line-derived neurotrophic factor infusion on IA and the expression of these five Kv mRNAs in injured A-fiber neurons using the in vitro patch clamp technique and in situ hybridization histochemistry. Glial cell line-derived neurotrophic factor infusion reversed axotomy-induced reduction of the rheobase, elongation of first spike duration, and depolarization of the resting membrane potential. L5 spinal nerve ligation significantly reduced the current density of IA and glial cell line-derived neurotrophic factor treatment reversed the reduction. Among the examined Kv mRNAs, only the change in Kv4.1-expression was parallel with the change in IA after spinal nerve ligation and glial cell line-derived neurotrophic factor treatment. These findings suggest that glial cell line-derived neurotrophic factor should reduce the hyperexcitability of injured A-fiber primary afferents by IA recurrence. Among the five IA-related Kv channels, Kv4.1 should be a key channel, which account for this IA recurrence.
Collapse
Affiliation(s)
- Masamichi Shinoda
- 1 Department of Physiology, Nihon University School of Dentistry, Surugadai, Chiyoda-ku, Tokyo, Japan
| | - Tetsuo Fukuoka
- 2 Department of Anatomy and Neuroscience, Hyogo College of Medicine, Mukogawa-cho, Nishinomiya, Hyogo, Japan.,3 Fukuoka Clinic, Kasuga, Suita, Osaka, Japan
| | - Mamoru Takeda
- 4 Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Fuchinobe, Chuo-ku, Sagamihara, Japan
| | - Koichi Iwata
- 1 Department of Physiology, Nihon University School of Dentistry, Surugadai, Chiyoda-ku, Tokyo, Japan
| | - Koichi Noguchi
- 2 Department of Anatomy and Neuroscience, Hyogo College of Medicine, Mukogawa-cho, Nishinomiya, Hyogo, Japan
| |
Collapse
|
18
|
Li ZH, Cui D, Qiu CJ, Song XJ. Cyclic nucleotide signaling in sensory neuron hyperexcitability and chronic pain after nerve injury. NEUROBIOLOGY OF PAIN 2019; 6:100028. [PMID: 31223142 PMCID: PMC6565612 DOI: 10.1016/j.ynpai.2019.100028] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 11/08/2022]
Abstract
Activation of cAMP-PKA and cGMP-PKG pathways contributes to injury-induced sensory neuron hyperexcitability. Activation of cAMP and cGMP contributes to the development of bone cancer pain. PAR2 activation mediates injury-induced cAMP-dependent sensory neuron hyperexcitability.
The cyclic nucleotide signaling, including cAMP-PKA and cGMP-PKG pathways, has been well known to play critical roles in regulating cellular growth, metabolism and many other intracellular processes. In recent years, more and more studies have uncovered the roles of cAMP and cGMP in the nervous system. The cAMP and cGMP signaling mediates chronic pain induced by different forms of injury and stress. Here we summarize the roles of cAMP-PKA and cGMP-PKG signaling pathways in the pathogenesis of chronic pain after nerve injury. In addition, acute dissociation and chronic compression of the dorsal root ganglion (DRG) neurons, respectively, leads to neural hyperexcitability possibly through PAR2 activation-dependent activation of cAMP-PKA pathway. Clinically, radiotherapy can effectively alleviate bone cancer pain at least partly through inhibiting the cancer cell-induced activation of cAMP-PKA pathway. Roles of cyclic nucleotide signaling in neuropathic and inflammatory pain are also seen in many other animal models and are involved in many pro-nociceptive mechanisms including the activation of hyperpolarization-activated cyclic nucleotide (HCN)-modulated ion channels and the exchange proteins directly activated by cAMP (EPAC). Further understanding the roles of cAMP and cGMP signaling in the pathogenesis of chronic pain is theoretically significant and clinically valuable for treatment of chronic pain.
Collapse
Affiliation(s)
- Ze-Hua Li
- Department of Biology, SUSTech Center for Pain Medicine, and Medical School, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.,Department of Anesthesiology and Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education of China), Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China
| | - Dong Cui
- Department of Biology, SUSTech Center for Pain Medicine, and Medical School, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.,Department of Anesthesiology and Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education of China), Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China
| | - Cheng-Jie Qiu
- Department of Biology, SUSTech Center for Pain Medicine, and Medical School, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Xue-Jun Song
- Department of Biology, SUSTech Center for Pain Medicine, and Medical School, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.,Department of Anesthesiology and Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education of China), Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China
| |
Collapse
|
19
|
Abstract
Obesity is often associated with increased pain, but little is known about the effects of obesity and diet on postoperative pain. In this study, effects of diet and obesity were examined in the paw incision model, a preclinical model of postoperative pain. Long-Evans rats were fed high-fat diet (40% calories from butter fat) or low-fat normal chow. Male rats fed high-fat diet starting 6 weeks before incision (a diet previously shown to induce markers of obesity) had prolonged mechanical hypersensitivity and an overall increase in spontaneous pain in response to paw incision, compared with normal chow controls. Diet effects in females were minor. Removing high-fat diet for 2 weeks before incision reversed the diet effects on pain behaviors, although this was not enough time to reverse high-fat diet-induced weight gain. A shorter (1 week) exposure to high-fat diet before incision also increased pain behaviors in males, albeit to a lesser degree. The 6-week high-fat diet increased macrophage density as examined immunohistochemically in lumbar dorsal root ganglion even before paw incision, especially in males, and sensitized responses of peritoneal macrophages to lipopolysaccharide stimuli in vitro. The nerve regeneration marker growth-associated protein 43 (GAP43) in skin near the incision (day 4) was higher in the high-fat diet group, and wound healing was delayed. In summary, high-fat diet increased postoperative pain particularly in males, but some diet effects did not depend on weight gain. Even short-term dietary manipulations, that do not affect obesity, may enhance postoperative pain.
Collapse
|
20
|
Role of Na V1.6 and Na Vβ4 Sodium Channel Subunits in a Rat Model of Low Back Pain Induced by Compression of the Dorsal Root Ganglia. Neuroscience 2019; 402:51-65. [PMID: 30699332 DOI: 10.1016/j.neuroscience.2019.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 01/18/2023]
Abstract
Low back pain is a common cause of chronic pain and disability. It is modeled in rodents by chronically compressing the lumbar dorsal root ganglia (DRG) with small metal rods, resulting in ipsilateral mechanical and cold hypersensitivity, and hyperexcitability of sensory neurons. Sodium channels are implicated in this hyperexcitability, but the responsible isoforms are unknown. In this study, we used siRNA-mediated knockdown of the pore-forming NaV1.6 and regulatory NaVβ4 sodium channel isoforms that have been previously implicated in a different model of low back pain caused by locally inflaming the L5 DRG. Knockdown of either subunit markedly reduced spontaneous pain and mechanical and cold hypersensitivity induced by DRG compression, and reduced spontaneous activity and hyperexcitability of sensory neurons with action potentials <1.5 msec (predominately cells with myelinated axons, based on conduction velocities measured in a subset of cells) 4 days after DRG compression. These results were similar to those previously obtained in the DRG inflammation model and some neuropathic pain models, in which sensory neurons other than nociceptors seem to play key roles. The cytokine profiles induced by DRG compression and DRG inflammation were also very similar, with upregulation of several type 1 pro-inflammatory cytokines and downregulation of type 2 anti-inflammatory cytokines. Surprisingly, the cytokine profile was largely unaffected by NaVβ4 knockdown in either model. The NaV1.6 channel, and the NaVβ4 subunit that can regulate NaV1.6 to enhance repetitive firing, play key roles in both models of low back pain; targeting the abnormal spontaneous activity they generate may have therapeutic value.
Collapse
|
21
|
Joubert F, Acosta MDC, Gallar J, Fakih D, Sahel JA, Baudouin C, Bodineau L, Mélik Parsadaniantz S, Réaux-Le Goazigo A. Effects of corneal injury on ciliary nerve fibre activity and corneal nociception in mice: A behavioural and electrophysiological study. Eur J Pain 2018; 23:589-602. [DOI: 10.1002/ejp.1332] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 09/18/2018] [Accepted: 10/20/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Fanny Joubert
- INSERM; CNRS; Institut de la Vision; Sorbonne Université; Paris France
| | - Maria del Carmen Acosta
- Instituto de Neurosciencas; Universidad Miguel Hernández-CSIC; San Juan de Alicante; Alicante Spain
| | - Juana Gallar
- Instituto de Neurosciencas; Universidad Miguel Hernández-CSIC; San Juan de Alicante; Alicante Spain
| | - Darine Fakih
- INSERM; CNRS; Institut de la Vision; Sorbonne Université; Paris France
- Laboratoires Théa; Clermont-Ferrand France
| | - José-Alain Sahel
- INSERM; CNRS; Institut de la Vision; Sorbonne Université; Paris France
- INSERM-DGOS CIC 1423; CHNO des Quinze-Vingts; DHU Sight Restore; Paris France
| | - Christophe Baudouin
- INSERM; CNRS; Institut de la Vision; Sorbonne Université; Paris France
- INSERM-DGOS CIC 1423; CHNO des Quinze-Vingts; DHU Sight Restore; Paris France
- University Versailles Saint Quentin en Yvelines; Versailles France
| | - Laurence Bodineau
- INSERM; Sorbonne Université; UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique; Paris France
| | | | | |
Collapse
|
22
|
Black BJ, Atmaramani R, Plagens S, Campbell ZT, Dussor G, Price TJ, Pancrazio JJ. Emerging neurotechnology for antinoceptive mechanisms and therapeutics discovery. Biosens Bioelectron 2018; 126:679-689. [PMID: 30544081 DOI: 10.1016/j.bios.2018.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 11/01/2018] [Accepted: 11/10/2018] [Indexed: 12/20/2022]
Abstract
The tolerance, abuse, and potential exacerbation associated with classical chronic pain medications such as opioids creates a need for alternative therapeutics. Phenotypic screening provides a complementary approach to traditional target-based drug discovery. Profiling cellular phenotypes enables quantification of physiologically relevant traits central to a disease pathology without prior identification of a specific drug target. For complex disorders such as chronic pain, which likely involves many molecular targets, this approach may identify novel treatments. Sensory neurons, termed nociceptors, are derived from dorsal root ganglia (DRG) and can undergo changes in membrane excitability during chronic pain. In this review, we describe phenotypic screening paradigms that make use of nociceptor electrophysiology. The purpose of this paper is to review the bioelectrical behavior of DRG neurons, signaling complexity in sensory neurons, various sensory neuron models, assays for bioelectrical behavior, and emerging efforts to leverage microfabrication and microfluidics for assay development. We discuss limitations and advantages of these various approaches and offer perspectives on opportunities for future development.
Collapse
Affiliation(s)
- Bryan J Black
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA.
| | - Rahul Atmaramani
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| | - Sarah Plagens
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| | - Zachary T Campbell
- Department of Biological Sciences, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| | - Gregory Dussor
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| | - Theodore J Price
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| | - Joseph J Pancrazio
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA
| |
Collapse
|
23
|
Djouhri L, Smith T, Alotaibi M, Weng X. Membrane potential oscillations are not essential for spontaneous firing generation in L4 Aβ-afferent neurons after L5 spinal nerve axotomy and are not mediated by HCN channels. Exp Physiol 2018; 103:1145-1156. [PMID: 29860719 DOI: 10.1113/ep087013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/23/2018] [Indexed: 01/01/2023]
Abstract
NEW FINDINGS What is the central question of this study? Is spontaneous activity (SA) in L4 dorsal root ganglion (DRG) neurons induced by L5 spinal nerve axotomy associated with membrane potential oscillations in these neurons, and if so, are these membrane oscillations mediated by HCN channels? What is the main finding and its importance? Unlike injured L5 DRG neurons, which have been shown to be incapable of firing spontaneously without membrane potential oscillations, membrane potential oscillations are not essential for SA generation in conducting 'uninjured' L4 neurons, and they are not mediated by HCN channels. These findings suggest that the underlying cellular mechanisms of SA in injured and 'uninjured' DRG neurons induced by spinal nerve injury are distinct. ABSTRACT The underlying cellular and molecular mechanisms of peripheral neuropathic pain are not fully understood. However, preclinical studies using animal models suggest that this debilitating condition is driven partly by aberrant spontaneous activity (SA) in injured and uninjured dorsal root ganglion (DRG) neurons, and that SA in injured DRG neurons is triggered by subthreshold membrane potential oscillations (SMPOs). Here, using in vivo intracellular recording from control L4-DRG neurons, and ipsilateral L4-DRG neurons in female Wistar rats that had previously undergone L5 spinal nerve axotomy (SNA), we examined whether conducting 'uninjured' L4-DRG neurons in SNA rats exhibit SMPOs, and if so, whether such SMPOs are associated with SA in those L4 neurons, and whether they are mediated by hyperpolarization-activated cyclic nucleotide gated (HCN) channels. We found that 7 days after SNA: (a) none of the control A- or C-fibre DRG neurons showed SMPOs or SA, but 50%, 43% and 0% of spontaneously active cutaneous L4 Aβ-low threshold mechanoreceptors, Aβ-nociceptors and C-nociceptors exhibited SMPOs, respectively, in SNA rats with established neuropathic pain behaviors; (b) neither SMPOs nor SA in L4 Aβ-neurons was suppressed by blocking HCN channels with ZD7288 (10 mg kg-1 , i.v.); and (c) there is a tendency for female rats to show greater pain hypersensitivity than male rats. These results suggest that SMPOs are linked to SA only in some of the conducting L4 Aβ-neurons, that such oscillations are not a prerequisite for SA generation in those L4 A- or C-fibre neurons, and that HCN channels are not involved in their electrogenesis.
Collapse
Affiliation(s)
- L Djouhri
- Department of Physiology, College of Medicine, Alfaisal University, PO Box 50927, Riyadh, 11533, Saudi Arabia
| | - T Smith
- Wolfson CARD, Neurorestoration Group, Hodgkin Building, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - M Alotaibi
- Department of Physiology, College of Medicine, King Saud University, PO Box 7805, Riyadh, 11472, Saudi Arabia
| | - X Weng
- Department of Neurobiology and State Key Laboratory of Proteomics, Beijing Institute of Basic Medical Sciences, Beijing, 100850, China
| |
Collapse
|
24
|
Wang Y, Huo F. Inhibition of sympathetic sprouting in CCD rats by lacosamide. Eur J Pain 2018; 22:1641-1650. [PMID: 29758584 DOI: 10.1002/ejp.1246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2018] [Indexed: 12/25/2022]
Abstract
BACKGROUND Early hyperexcitability activity of injured nerve/neuron is critical for developing sympathetic nerve sprouting within dorsal root ganglia (DRG) since lacosamide (LCM), an anticonvulsant, inhibits Na+ channel. The present study tried to test the potential effect of LCM on inhibiting sympathetic sprouting in vivo. METHODS Lacosamide (50 mg/kg) was daily injected intraperitoneally into rats subjected to chronic compression DRG (CCD), an animal model of neuropathic pain that exhibits sympathetic nerve sprouting, for the 1st 7 days after injury. Mechanical sensitivity was tested from day 3 to day 18 after injury, and then DRGs were removed off. Immunohistochemical staining for tyrosine hydroxylase (TH) was examined to observe sympathetic sprouting, and patch-clamp recording was performed to test the excitability and Na+ current of DRG neurons. RESULTS Early systemic LCM treatment significantly reduced TH immunoreactivity density in injured DRG, lowered the excitability level of injured DRG neurons and increased paw withdrawal threshold. These effects on reducing sympathetic sprouting, inhibiting excitability and suppressing pain behaviour were observed 10 days after the end of early LCM injection. In vitro 100 μmol/L LCM instantly reduced the excitability of CCD neurons via inhibiting Na+ current and reducing the amplitude of AP. CONCLUSIONS All the findings suggest, for the first time, that early administration of LCM inhibited sympathetic sprouting and then alleviated neuropathic pain. SIGNIFICANCE Early LCM administration inhibited sympathetic sprouting within DRG in CCD rats via reducing hyperexcitability of neurons. Early LCM administration suppressed neuropathic pain in CCD rats.
Collapse
Affiliation(s)
- Y Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, China.,Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an, 710061, China
| | - F Huo
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, China.,Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an, 710061, China
| |
Collapse
|
25
|
Takkala P, Prescott SA. Using dynamic clamp to quantify pathological changes in the excitability of primary somatosensory neurons. J Physiol 2018; 596:2209-2227. [PMID: 29601637 PMCID: PMC5983269 DOI: 10.1113/jp275580] [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: 12/14/2017] [Accepted: 03/21/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Primary somatosensory neurons normally respond to somatic depolarization with transient spiking but can switch to repetitive spiking under pathological conditions. This switch in spiking pattern reflects a qualitative change in spike initiation dynamics and contributes to the hyperexcitability associated with chronic pain. Neurons can be converted to repetitive spiking by adding a virtual conductance using dynamic clamp. By titrating the conductance to determine how much must be added to cause repetitive spiking, we found that small cells are more susceptible to switching (i.e. required less added conductance) than medium-large cells. By measuring how much less conductance is required to cause repetitive spiking when dynamic clamp was combined with other pathomimetic manipulations (e.g. application of inflammatory mediators), we measured how much each manipulation facilitated repetitive spiking. Our results suggest that many pathological factors facilitate repetitive spiking but that the switch to repetitive spiking requires the cumulative effect of many co-occurring factors. ABSTRACT Primary somatosensory neurons become hyperexcitable in many chronic pain conditions. Hyperexcitability can include a switch from transient to repetitive spiking during sustained somatic depolarization. This switch results from diverse pathological processes that impact ion channel expression or function. Because multiple pathological processes co-occur, isolating how much each contributes to switching the spiking pattern is difficult. Our approach to this challenge involves adding a virtual sodium conductance via dynamic clamp. The magnitude of that conductance was titrated to determine the minimum required to enable rheobasic stimulation to evoke repetitive spiking. The minimum required conductance, termed g¯ Na ∗, was re-measured before and during manipulations designed to model various pathological processes in vitro. The reduction in g¯ Na ∗ caused by each pathomimetic manipulation reflects how much the modelled process contributes to switching the spiking pattern. We found that elevating extracellular potassium or applying inflammatory mediators reduced g¯ Na ∗ whereas direct hyperpolarization had no effect. Inflammatory mediators reduced g¯ Na ∗ more in medium-large (>30 μm diameter) neurons than in small (⩽30 μm diameter) neurons, but had equivalent effects in cutaneous and muscle afferents. The repetitive spiking induced by dynamic clamp was also found to differ between small and medium-large neurons, thus revealing latent differences in adaptation. Our study demonstrates a novel way to determine to what extent individual pathological factors facilitate repetitive spiking. Our results suggest that most factors facilitate but do not cause repetitive spiking on their own, and, therefore, that a switch to repetitive spiking results from the cumulative effect of many co-occurring factors.
Collapse
Affiliation(s)
- Petri Takkala
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada, M5G 0A4.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Steven A Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada, M5G 0A4.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.,Department of Physiology and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Ontario, Canada, M5S 1A8
| |
Collapse
|
26
|
Wang T, Hurwitz O, Shimada SG, Tian D, Dai F, Zhou J, Ma C, LaMotte RH. Anti-nociceptive effects of bupivacaine-encapsulated PLGA nanoparticles applied to the compressed dorsal root ganglion in mice. Neurosci Lett 2018; 668:154-158. [PMID: 29355697 DOI: 10.1016/j.neulet.2018.01.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/05/2018] [Accepted: 01/16/2018] [Indexed: 11/24/2022]
Abstract
Bupivacaine is a commonly used local anesthetic in postoperative pain management. We evaluated the effects of a prolonged, local delivery of bupivacaine on pain behavior accompanying a chronic compression of the dorsal root ganglion (CCD) - an animal model of radicular pain. Poly(lactide-coglycolide) (PLGA) nanoparticles encapsulating bupivacaine were injected unilaterally into the L3 and L4 DRGs of mice just before producing CCD by implanting a stainless-steel rod in the intervertebral foramen of each ganglion. Behavioral sensitivity to punctate mechanical stimuli (Von Frey filaments) of different forces of indentation, delivered to each hind paw, was measured before and on subsequent days of testing after the CCD. Nanoparticles were spherical in morphology and 150 ± 10 nm in diameter. Bupivacaine was steadily released as measured in vitro over 35 days. A dye that was encapsulated in the nanoparticles was found in the intact DRG after 2 weeks. CCD alone or with injection of blank (control) nanoparticles produced a behavioral hypersensitivity to the punctate stimuli on the ipsilateral paw without affecting sensitivity on the contralateral, over a period of 7-14 days. The hypersensitivity was manifested as an increased incidence of paw-withdrawal to indentation forces normally below threshold (allodynia) and an increased shaking to a filament force that always elicited withdrawal prior to CCD (hyperalgesia). In contrast, nanoparticles with bupivacaine prevented any manifestation of allodynia or hyperalgesia on the ipsilateral hind paw while leaving normal nociceptive responses largely intact on both hind paws. CCD induced behavioral hypersensitivity to nociceptive stimuli is known to be associated with a hyperexcitability of sensory neurons originating in the compressed ganglion. We hypothesize that bupivacaine-loaded PLGA nanoparticles may prevent the occurrence of this neuronal hyperexcitability without reducing the nociceptive information normally conducted from the periphery to the central nervous system. The slow, sustained delivery of bupivacaine by nanoparticles may provide a means of preventing the occurrence of postoperative neuronal hyperexcitability that could develop into chronic neuropathic pain.
Collapse
Affiliation(s)
- Tao Wang
- Department of Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China; Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA
| | - Olivia Hurwitz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA
| | - Steven G Shimada
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA
| | - Daofeng Tian
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Feng Dai
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA
| | - Jiangbing Zhou
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Chao Ma
- Department of Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China; Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA.
| | - Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, 06520-8051, USA.
| |
Collapse
|
27
|
Sensitivity of Computed Tomography Compared With that of Magnetic Resonance Myelography in the Presurgical Diagnosis of Foraminal or Extraforaminal Entrapment at the Lumbosacral Junction. Clin Spine Surg 2018; 31:E13-E18. [PMID: 28059947 DOI: 10.1097/bsd.0000000000000471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
STUDY DESIGN This is a retrospective analysis. OBJECTIVE To investigate and compare the sensitivities of computed tomography (CT) and magnetic resonance myelography (MRM) in the presurgical diagnosis of foraminal or extraforaminal entrapment of the L5 nerve. SUMMARY OF BACKGROUND DATA CT is more clinically available than MRM. Foraminal or extraforaminal entrapment at the lumbosacral junction may cause L5 radiculopathy but is difficult to diagnose. Asymmetric enlargement of the anterior primary division (APD) of the L5 nerve on preoperative CT and dorsal root ganglion (DRG) swelling and abnormal L5 nerve course on MRM coronal images have been examined in cases of foraminal or extraforaminal L5 nerve entrapment, but have not been compared directly. MATERIALS AND METHODS Ninety-five patients (mean age 63 y; 28-85 y) with L5 nerve entrapment at the lumbosacral junction who underwent preoperative CT and MRM, and microsurgical decompression by a single surgeon (K.-H.M.) from January 2010 to June 2014 were included. Symptomatic sites were diagnosed by confirming L5 nerve entrapment intraoperatively. Two spinal surgeons independently compared the bilateral APD diameters of the L5 nerve on CT and the L5 nerve courses and DRG swelling on MRM coronal images. RESULTS The interobserver agreement of asymmetric APD swelling on CT and abnormal nerve course and DRG swelling on MRM were excellent (κ=0.808, 0.811, and 0.849, respectively), and the sensitivities were 81%, 84%, and 82% on the right, and 86%, 92%, and 90% on the left sides, respectively. There was no statistically significant difference in the sensitivity between APD swelling on CT and an abnormal nerve course or DRG swelling on MRM on the right (P=1.000 and 0.789) and left (P=0.727 and 1.000) sides, respectively. CONCLUSIONS CT has comparable sensitivity to MRM for the presurgical diagnosis of L5 nerve entrapment at the lumbosacral junction. LEVEL OF EVIDENCE Level II.
Collapse
|
28
|
Xie RG, Chu WG, Hu SJ, Luo C. Characterization of Different Types of Excitability in Large Somatosensory Neurons and Its Plastic Changes in Pathological Pain States. Int J Mol Sci 2018; 19:ijms19010161. [PMID: 29303989 PMCID: PMC5796110 DOI: 10.3390/ijms19010161] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 12/30/2017] [Accepted: 01/02/2018] [Indexed: 12/16/2022] Open
Abstract
Sensory neuron types have been distinguished by distinct morphological and transcriptional characteristics. Excitability is the most fundamental functional feature of neurons. Mathematical models described by Hodgkin have revealed three types of neuronal excitability based on the relationship between firing frequency and applied current intensity. However, whether natural sensory neurons display different functional characteristics in terms of excitability and whether this excitability type undergoes plastic changes under pathological pain states have remained elusive. Here, by utilizing whole-cell patch clamp recordings, behavioral and pharmacological assays, we demonstrated that large dorsal root ganglion (DRG) neurons can be classified into three classes and four subclasses based on their excitability patterns, which is similar to mathematical models raised by Hodgkin. Analysis of hyperpolarization-activated cation current (Ih) revealed different magnitude of Ih in different excitability types of large DRG neurons, with higher Ih in Class 2-1 than that in Class 1, 2-2 and 3. This indicates a crucial role of Ih in the determination of excitability type of large DRG neurons. More importantly, this pattern of excitability displays plastic changes and transition under pathological pain states caused by peripheral nerve injury. This study sheds new light on the functional characteristics of large DRG neurons and extends functional classification of large DRG neurons by integration of transcriptomic and morphological characteristics.
Collapse
Affiliation(s)
- Rou-Gang Xie
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, China.
| | - Wen-Guang Chu
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, China.
| | - San-Jue Hu
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, China.
| | - Ceng Luo
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, China.
| |
Collapse
|
29
|
Xiong W, Ping X, Ripsch MS, Chavez GSC, Hannon HE, Jiang K, Bao C, Jadhav V, Chen L, Chai Z, Ma C, Wu H, Feng J, Blesch A, White FA, Jin X. Enhancing excitatory activity of somatosensory cortex alleviates neuropathic pain through regulating homeostatic plasticity. Sci Rep 2017; 7:12743. [PMID: 28986567 PMCID: PMC5630599 DOI: 10.1038/s41598-017-12972-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023] Open
Abstract
Central sensitization and network hyperexcitability of the nociceptive system is a basic mechanism of neuropathic pain. We hypothesize that development of cortical hyperexcitability underlying neuropathic pain may involve homeostatic plasticity in response to lesion-induced somatosensory deprivation and activity loss, and can be controlled by enhancing cortical activity. In a mouse model of neuropathic pain, in vivo two-photon imaging and patch clamp recording showed initial loss and subsequent recovery and enhancement of spontaneous firings of somatosensory cortical pyramidal neurons. Unilateral optogenetic stimulation of cortical pyramidal neurons both prevented and reduced pain-like behavior as detected by bilateral mechanical hypersensitivity of hindlimbs, but corpus callosotomy eliminated the analgesic effect that was ipsilateral, but not contralateral, to optogenetic stimulation, suggesting involvement of inter-hemispheric excitatory drive in this effect. Enhancing activity by focally blocking cortical GABAergic inhibition had a similar relieving effect on the pain-like behavior. Patch clamp recordings from layer V pyramidal neurons showed that optogenetic stimulation normalized cortical hyperexcitability through changing neuronal membrane properties and reducing frequency of excitatory postsynaptic events. We conclude that development of neuropathic pain involves abnormal homeostatic activity regulation of somatosensory cortex, and that enhancing cortical excitatory activity may be a novel strategy for preventing and controlling neuropathic pain.
Collapse
Affiliation(s)
- Wenhui Xiong
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Matthew S Ripsch
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Grace Santa Cruz Chavez
- Department of Biomedical Engineering, Purdue School of Engineering and Technology. IUPUI, Indianapolis, USA
| | - Heidi Elise Hannon
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Kewen Jiang
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chunhui Bao
- Shanghai Research Institute of Acupuncture-Moxibustion and Meridian, Shanghai, China
| | - Vaishnavi Jadhav
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Lifang Chen
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Acupuncture, Zhejiang Traditional Chinese Medical University and the Third Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Zhi Chai
- Research Center of Neurobiology, Shanxi University of Traditional Chinese Medicine, Taiyuan, China
| | - Cungen Ma
- Research Center of Neurobiology, Shanxi University of Traditional Chinese Medicine, Taiyuan, China
| | - Huangan Wu
- Shanghai Research Institute of Acupuncture-Moxibustion and Meridian, Shanghai, China
| | - Jianqiao Feng
- Department of Acupuncture, Zhejiang Traditional Chinese Medical University and the Third Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Armin Blesch
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Fletcher A White
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN 46202, USA.
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| |
Collapse
|
30
|
Yu Y, Huang X, Di Y, Qu L, Fan N. Effect of CXCL12/CXCR4 signaling on neuropathic pain after chronic compression of dorsal root ganglion. Sci Rep 2017; 7:5707. [PMID: 28720830 PMCID: PMC5515923 DOI: 10.1038/s41598-017-05954-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 06/07/2017] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain is a complex, chronic pain state that often accompanies tissue damage, inflammation or injury of the nervous system. However the underlying molecular mechanisms still remain unclear. Here, we showed that CXCL12 and CXCR4 were upregulated in the dorsal root ganglion (DRG) after chronic compression of DRG (CCD), and some CXCR4 immunopositive neurons were also immunopositive for the nociceptive neuronal markers IB4, TRPV1, CGRP, and substance P. The incidence and amplitude of CXCL12-induced Ca2+ response in primary sensory neurons from CCD mice was significantly increased compared to those from control animals. CXCL12 depolarized the resting membrane potential, decreased the rheobase, and increased the number of action potentials evoked by a depolarizing current at 2X rheobase in neurons from CCD mice. The mechanical and thermal hypernociception after CCD was attenuated by administration of a CXCR4 antagonist AMD3100. These findings suggest that CXCL12/CXCR4 signaling contributes to hypernociception after CCD, and targeting CXCL12/CXCR4 signaling pathway may alleviate neuropathic pain.
Collapse
Affiliation(s)
- Yang Yu
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China
| | - Xini Huang
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China
| | - Yuwei Di
- Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080, China
| | - Lintao Qu
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University School of Medicine, 725N. Wolfe St., Baltimore, MD, 21205, USA
| | - Ni Fan
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China.
| |
Collapse
|
31
|
Localized Sympathectomy Reduces Mechanical Hypersensitivity by Restoring Normal Immune Homeostasis in Rat Models of Inflammatory Pain. J Neurosci 2017; 36:8712-25. [PMID: 27535916 DOI: 10.1523/jneurosci.4118-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/09/2016] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED Some forms of chronic pain are maintained or enhanced by activity in the sympathetic nervous system (SNS), but attempts to model this have yielded conflicting findings. The SNS has both pro- and anti-inflammatory effects on immunity, confounding the interpretation of experiments using global sympathectomy methods. We performed a "microsympathectomy" by cutting the ipsilateral gray rami where they entered the spinal nerves near the L4 and L5 DRG. This led to profound sustained reductions in pain behaviors induced by local DRG inflammation (a rat model of low back pain) and by a peripheral paw inflammation model. Effects of microsympathectomy were evident within one day, making it unlikely that blocking sympathetic sprouting in the local DRGs or hindpaw was the sole mechanism. Prior microsympathectomy greatly reduced hyperexcitability of sensory neurons induced by local DRG inflammation observed 4 d later. Microsympathectomy reduced local inflammation and macrophage density in the affected tissues (as indicated by paw swelling and histochemical staining). Cytokine profiling in locally inflamed DRG showed increases in pro-inflammatory Type 1 cytokines and decreases in the Type 2 cytokines present at baseline, changes that were mitigated by microsympathectomy. Microsympathectomy was also effective in reducing established pain behaviors in the local DRG inflammation model. We conclude that the effect of sympathetic fibers in the L4/L5 gray rami in these models is pro-inflammatory. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some chronic inflammatory pain conditions. SIGNIFICANCE STATEMENT Sympathetic blockade is used for many pain conditions, but preclinical studies show both pro- and anti-nociceptive effects. The sympathetic nervous system also has both pro- and anti-inflammatory effects on immune tissues and cells. We examined effects of a very localized sympathectomy. By cutting the gray rami to the spinal nerves near the lumbar sensory ganglia, we avoided widespread sympathetic denervation. This procedure profoundly reduced mechanical pain behaviors induced by a back pain model and a model of peripheral inflammatory pain. One possible mechanism was reduction of inflammation in the sympathetically denervated regions. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some inflammatory conditions.
Collapse
|
32
|
Allette YM, Kim Y, Randolph AL, Smith JA, Ripsch MS, White FA. Decoy peptide targeted to Toll-IL-1R domain inhibits LPS and TLR4-active metabolite morphine-3 glucuronide sensitization of sensory neurons. Sci Rep 2017. [PMID: 28623271 PMCID: PMC5473853 DOI: 10.1038/s41598-017-03447-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Accumulating evidence indicates that Toll-like receptor (TLR) signaling adapter protein interactions with Toll/Interleukin-1 Receptor (TIR) domains present in sensory neurons may modulate neuropathic pain states. Following ligand interaction with TLRs, TIR serves to both initiate intracellular signaling and facilitate recruitment of signaling adapter proteins to the intracytoplasmic domain. Although TLR TIR is central to a number of TLR signaling cascades, its role in sensory neurons is poorly understood. In this study we investigated the degree to which TLR TIR decoy peptide modified to include a TAT sequence (Trans-Activator of Transcription gene in HIV; TAT-4BB) affected LPS-induced intracellular calcium flux and excitation in sensory neurons, and behavioral changes due to TLR4 active metabolite, morphine-3-glucuronide (M3G) exposure in vivo. TAT-4BB inhibited LPS-induced calcium changes in a majority of sensory neurons and decreased LPS-dependent neuronal excitability in small diameter neurons. Acute systemic administration of the TAT-4BB reversed M3G-induced tactile allodynia in a dose-dependent manner but did not affect motor activity, anxiety or responses to noxious thermal stimulus. These data suggest that targeting TLR TIR domains may provide novel pharmacological targets to reduce or reverse TLR4-dependent pain behavior in the rodent.
Collapse
Affiliation(s)
- Yohance M Allette
- Medical Science Training Program, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Youngsook Kim
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Aaron L Randolph
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Jared A Smith
- Medical Science Training Program, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Matthew S Ripsch
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Fletcher A White
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA.
| |
Collapse
|
33
|
Liu DL, Wang X, Chu WG, Lu N, Han WJ, Du YK, Hu SJ, Bai ZT, Wu SX, Xie RG, Luo C. Chronic cervical radiculopathic pain is associated with increased excitability and hyperpolarization-activated current ( I h) in large-diameter dorsal root ganglion neurons. Mol Pain 2017; 13:1744806917707127. [PMID: 28587505 PMCID: PMC5466279 DOI: 10.1177/1744806917707127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cervical radiculopathic pain is a very common symptom that may occur with cervical
spondylosis. Mechanical allodynia is often associated with cervical radiculopathic pain
and is inadequately treated with current therapies. However, the precise mechanisms
underlying cervical radiculopathic pain-associated mechanical allodynia have remained
elusive. Compelling evidence from animal models suggests a role of large-diameter dorsal
root ganglion neurons and plasticity of spinal circuitry attached with Aβ fibers in
mediating neuropathic pain. Whether cervical radiculopathic pain condition induces plastic
changes of large-diameter dorsal root ganglion neurons and what mechanisms underlie these
changes are yet to be known. With combination of patch-clamp recording,
immunohistochemical staining, as well as behavioral surveys, we demonstrated that upon
chronic compression of C7/8 dorsal root ganglions, large-diameter cervical dorsal root
ganglion neurons exhibited frequent spontaneous firing together with hyperexcitability.
Quantitative analysis of hyperpolarization-activated cation current
(Ih) revealed that Ih was
greatly upregulated in large dorsal root ganglion neurons from cervical radiculopathic
pain rats. This increased Ih was supported by the enhanced
expression of hyperpolarization-activated, cyclic nucleotide-modulated channels subunit 3
in large dorsal root ganglion neurons. Blockade of Ih with
selective antagonist, ZD7288 was able to eliminate the mechanical allodynia associated
with cervical radiculopathic pain. This study sheds new light on the functional plasticity
of a specific subset of large-diameter dorsal root ganglion neurons and reveals a novel
mechanism that could underlie the mechanical allodynia associated with cervical
radiculopathy.
Collapse
Affiliation(s)
- Da-Lu Liu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,2 Department of Radiation Medicine, Faculty of Preventive Medicine, Fourth Military Medical University, Xi'an, China
| | - Xu Wang
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,3 Research Center for Resource Polypeptide Drugs and College of Life Sciences, Yanan University, Yanan, China
| | - Wen-Guang Chu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Na Lu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,4 ART Center, Northwest Women's and Children's Hospital, Xi'an, China
| | - Wen-Juan Han
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Yi-Kang Du
- 5 The First Brigade, Fourth Military Medical University, Xi'an, China
| | - San-Jue Hu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Zhan-Tao Bai
- 3 Research Center for Resource Polypeptide Drugs and College of Life Sciences, Yanan University, Yanan, China
| | - Sheng-Xi Wu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Rou-Gang Xie
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Ceng Luo
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| |
Collapse
|
34
|
Li AL, Zhang JD, Xie W, Strong JA, Zhang JM. Inflammatory Changes in Paravertebral Sympathetic Ganglia in Two Rat Pain Models. Neurosci Bull 2017; 34:85-97. [PMID: 28534262 DOI: 10.1007/s12264-017-0142-1] [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: 02/09/2017] [Accepted: 03/01/2017] [Indexed: 12/24/2022] Open
Abstract
Injury to peripheral nerves can lead to neuropathic pain, along with well-studied effects on sensory neurons, including hyperexcitability, abnormal spontaneous activity, and neuroinflammation in the sensory ganglia. Neuropathic pain can be enhanced by sympathetic activity. Peripheral nerve injury may also damage sympathetic axons or expose them to an inflammatory environment. In this study, we examined the lumbar sympathetic ganglion responses to two rat pain models: ligation of the L5 spinal nerve, and local inflammation of the L5 dorsal root ganglion (DRG), which does not involve axotomy. Both models resulted in neuroinflammatory changes in the sympathetic ganglia, as indicated by macrophage responses, satellite glia activation, and increased numbers of T cells, along with very modest increases in sympathetic neuron excitability (but not spontaneous activity) measured in ex vivo recordings. The spinal nerve ligation model generally caused larger responses than DRG inflammation. Plasticity of the sympathetic system should be recognized in studies of sympathetic effects on pain.
Collapse
Affiliation(s)
- Ai-Ling Li
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA.,Department of Psychological and Brain Science, Indiana University Bloomington, 702 N Walnut Grove Ave., Bloomington, IN, 47405, USA
| | - Jing-Dong Zhang
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Wenrui Xie
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Judith A Strong
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Jun-Ming Zhang
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA.
| |
Collapse
|
35
|
Upregulation of the sodium channel NaVβ4 subunit and its contributions to mechanical hypersensitivity and neuronal hyperexcitability in a rat model of radicular pain induced by local dorsal root ganglion inflammation. Pain 2017; 157:879-891. [PMID: 26785322 DOI: 10.1097/j.pain.0000000000000453] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High-frequency spontaneous firing in myelinated sensory neurons plays a key role in initiating pain behaviors in several different models, including the radicular pain model in which the rat lumbar dorsal root ganglia (DRG) are locally inflamed. The sodium channel isoform NaV1.6 contributes to pain behaviors and spontaneous activity in this model. Among all isoforms in adult DRG, NaV1.6 is the main carrier of tetrodotoxin-sensitive resurgent Na currents that allow high-frequency firing. Resurgent currents flow after a depolarization or action potential, as a blocking particle exits the pore. In most neurons, the regulatory β4 subunit is potentially the endogenous blocker. We used in vivo siRNA-mediated knockdown of NaVβ4 to examine its role in the DRG inflammation model. NaVβ4 but not control siRNA almost completely blocked mechanical hypersensitivity induced by DRG inflammation. Microelectrode recordings in isolated whole DRG showed that NaVβ4 siRNA blocked the inflammation-induced increase in spontaneous activity of Aβ neurons and reduced repetitive firing and other measures of excitability. NaVβ4 was preferentially expressed in larger diameter cells; DRG inflammation increased its expression, and this was reversed by NaVβ4 siRNA, based on immunohistochemistry and Western blotting. NaVβ4 siRNA also reduced immunohistochemical NaV1.6 expression. Patch-clamp recordings of tetrodotoxin-sensitive Na currents in acutely cultured medium diameter DRG neurons showed that DRG inflammation increased transient and especially resurgent current, effects blocked by NaVβ4 siRNA. NaVβ4 may represent a more specific target for pain conditions that depend on myelinated neurons expressing NaV1.6.
Collapse
|
36
|
Gong K, Ohara PT, Jasmin L. Patch Clamp Recordings on Intact Dorsal Root Ganglia from Adult Rats. J Vis Exp 2016. [PMID: 27768031 DOI: 10.3791/54287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Patch clamp studies from dorsal root ganglia (DRGs) neurons have increased our understanding of the peripheral nervous system. Currently, the majority of recordings are conducted on dissociated DRG neurons, which is a standard preparation for most laboratories. Neuronal properties, however, can be altered by axonal injury resulting from enzyme digestion used in acquiring dissociated neurons. Further, dissociated neuron preparations cannot fully represent the microenvironment of the DRG since loss of contact with satellite glial cells that surround the primary sensory neurons is an unavoidable consequence of this method. To overcome the limitations in using conventional dissociated DRG neurons for patch clamp recordings, in this report we describe a method to prepare intact DRGs and conduct patch clamp recordings on individual primary sensory neurons ex vivo. This approach permits the fast and straightforward preparation of intact DRGs, mimicking in vivo conditions by keeping DRG neurons associated with their surrounding satellite glial cells and basement membrane. Furthermore, the method avoids axonal injury from manipulation and enzyme digestion such as when dissociating DRGs. This ex vivo preparation can additionally be used to study the interaction between primary sensory neurons and satellite glial cells.
Collapse
Affiliation(s)
- Kerui Gong
- Department of Oral and Maxillofacial Surgery, University of California, San Francisco;
| | - Peter T Ohara
- Department of Anatomy, University of California, San Francisco
| | - Luc Jasmin
- Department of Oral and Maxillofacial Surgery, University of California, San Francisco;
| |
Collapse
|
37
|
Menichella DM, Jayaraj ND, Wilson HM, Ren D, Flood K, Wang XQ, Shum A, Miller RJ, Paller AS. Ganglioside GM3 synthase depletion reverses neuropathic pain and small fiber neuropathy in diet-induced diabetic mice. Mol Pain 2016; 12:12/0/1744806916666284. [PMID: 27590073 PMCID: PMC5011393 DOI: 10.1177/1744806916666284] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/22/2016] [Indexed: 12/23/2022] Open
Abstract
Background Small fiber neuropathy is a well-recognized complication of type 2 diabetes and has been shown to be responsible for both neuropathic pain and impaired wound healing. In previous studies, we have demonstrated that ganglioside GM3 depletion by knockdown of GM3 synthase fully reverses impaired wound healing in diabetic mice. However, the role of GM3 in neuropathic pain and small fiber neuropathy in diabetes is unknown. Purpose Determine whether GM3 depletion is able to reverse neuropathic pain and small fibers neuropathy and the mechanism of the reversal. Results We demonstrate that GM3 synthase knockout and the resultant GM3 depletion rescues the denervation in mouse footpad skin and fully reverses the neuropathic pain in diet-induced obese diabetic mice. In cultured dorsal root ganglia from diet-induced diabetic mice, GM3 depletion protects against increased intracellular calcium influx in vitro. Conclusions These studies establish ganglioside GM3 as a new candidate responsible for neuropathic pain and small fiber neuropathy in diabetes. Moreover, these observations indicate that systemic or topically applied interventions aimed at depleting GM3 may improve both the painful neuropathy and the wound healing impairment in diabetes by protecting against nerve end terminal degeneration, providing a disease-modifying approach to this common, currently intractable medical issue.
Collapse
Affiliation(s)
- Daniela M Menichella
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Nirupa D Jayaraj
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Heather M Wilson
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Dongjun Ren
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Kelsey Flood
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Xiao-Qi Wang
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Andrew Shum
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Richard J Miller
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Amy S Paller
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| |
Collapse
|
38
|
Serotonin type-1D receptor stimulation of A-type K(+) channel decreases membrane excitability through the protein kinase A- and B-Raf-dependent p38 MAPK pathways in mouse trigeminal ganglion neurons. Cell Signal 2016; 28:979-88. [PMID: 27156838 DOI: 10.1016/j.cellsig.2016.05.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 01/09/2023]
Abstract
Although recent studies have implicated serotonin 5-HT1B/D receptors in the nociceptive sensitivity of primary afferent neurons, the underlying molecular and cellular mechanisms remain unclear. In this study, we identified a novel functional role of the 5-HT1D receptor subtype in regulating A-type potassium (K(+)) currents (IA) as well as membrane excitability in small trigeminal ganglion (TG) neurons. We found that the selective activation of 5-HT1D, rather than 5-HT1B, receptors reversibly increased IA, while the sustained delayed rectifier K(+) current was unaffected. The 5-HT1D-mediated IA increase was associated with a depolarizing shift in the voltage dependence of inactivation. Blocking G-protein signaling with pertussis toxin or by intracellular application of a selective antibody raised against Gαo or Gβ abolished the 5-HT1D effect on IA. Inhibition of protein kinase A (PKA), but not of phosphatidylinositol 3-kinase or protein kinase C, abolished the 5-HT1D-mediated IA increase. Analysis of phospho-p38 (p-p38) revealed that activation of 5-HT1D, but not 5-HT1B, receptors significantly activated p38, while p-ERK and p-JNK were unaffected. The p38 MAPK inhibitor SB203580, but not its inactive analogue SB202474, and inhibition of B-Raf blocked the 5-HT1D-mediated IA response. Functionally, we observed a significantly decreased action potential firing rate induced by the 5-HT1D receptors; pretreatment with 4-aminopyridine abolished this effect. Taken together, these results suggest that the activation of 5-HT1D receptors selectively enhanced IA via the Gβγ of the Go-protein, PKA, and the sequential B-Raf-dependent p38 MAPK signaling cascade. This 5-HT1D receptor effect may contribute to neuronal hypoexcitability in small TG neurons.
Collapse
|
39
|
Impact of Opioid and Nonopioid Drugs on Postsurgical Pain Management in the Rat. PAIN RESEARCH AND TREATMENT 2016; 2016:8364762. [PMID: 27069684 PMCID: PMC4812481 DOI: 10.1155/2016/8364762] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/21/2016] [Indexed: 11/25/2022]
Abstract
Aim. Nonsteroidal anti-inflammatory drugs or opioids are commonly used to control surgical pain following veterinary and clinical procedures. This study evaluated the efficacy of postoperative ketorolac or buprenorphine following abdominal surgery. Main Methods. Mean arterial pressure (MAP), heart rate, animal activity, corticosterone levels, and a nociceptive sensitivity assay were used to evaluate 18 adult male Sprague-Dawley rats which underwent aortic artery occlusion for implantation of a radiotelemetry device. The animals were treated postoperatively with intraperitoneal injections of vehicle, ketorolac (10 mg/kg), or buprenorphine (0.06 mg/kg) every 8 hours for 3 days. Key Findings. There were no consistent significant changes in any of the telemetry parameters after treatment with ketorolac compared with no saline treatment with the exception of increased MAP in the buprenorphine group during the first 48 hours when compared with other treatment groups. There was a sustained increase in fecal corticosterone levels from baseline on days 2–7 with buprenorphine compared with vehicle- or ketorolac-treated animals. All treatment conditions displayed reduced paw withdrawal thresholds (PWTs) from day 1 to day 21 following surgery. Compared with the vehicle treatment group, buprenorphine-treated animals exhibited significantly lower PWT levels from day 4 to 14 days. Significance. Given the prolonged increase in fecal corticosterone levels and pronounced changes in tactile hyperalgesia behavior in rodents subjected to buprenorphine treatment, these data suggest that ketorolac may be superior to buprenorphine for the treatment of postprocedure pain behavior in rodents.
Collapse
|
40
|
Barbosa C, Cummins TR. Unusual Voltage-Gated Sodium Currents as Targets for Pain. CURRENT TOPICS IN MEMBRANES 2016; 78:599-638. [PMID: 27586296 DOI: 10.1016/bs.ctm.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons.
Collapse
Affiliation(s)
- C Barbosa
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - T R Cummins
- Indiana University School of Medicine, Indianapolis, IN, United States
| |
Collapse
|
41
|
Upregulation of Ih expressed in IB4-negative Aδ nociceptive DRG neurons contributes to mechanical hypersensitivity associated with cervical radiculopathic pain. Sci Rep 2015; 5:16713. [PMID: 26577374 PMCID: PMC4649360 DOI: 10.1038/srep16713] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 10/19/2015] [Indexed: 11/30/2022] Open
Abstract
Cervical radiculopathy represents aberrant mechanical hypersensitivity. Primary sensory neuron’s ability to sense mechanical force forms mechanotransduction. However, whether this property undergoes activity-dependent plastic changes and underlies mechanical hypersensitivity associated with cervical radiculopathic pain (CRP) is not clear. Here we show a new CRP model producing stable mechanical compression of dorsal root ganglion (DRG), which induces dramatic behavioral mechanical hypersensitivity. Amongst nociceptive DRG neurons, a mechanically sensitive neuron, isolectin B4 negative Aδ-type (IB4− Aδ) DRG neuron displays spontaneous activity with hyperexcitability after chronic compression of cervical DRGs. Focal mechanical stimulation on somata of IB4- Aδ neuron induces abnormal hypersensitivity. Upregulated HCN1 and HCN3 channels and increased Ih current on this subset of primary nociceptors underlies the spontaneous activity together with neuronal mechanical hypersensitivity, which further contributes to the behavioral mechanical hypersensitivity associated with CRP. This study sheds new light on the functional plasticity of a specific subset of nociceptive DRG neurons to mechanical stimulation and reveals a novel mechanism that could underlie the mechanical hypersensitivity associated with cervical radiculopathy.
Collapse
|
42
|
Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat. Neural Plast 2015; 2015:924728. [PMID: 26451259 PMCID: PMC4584224 DOI: 10.1155/2015/924728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/09/2015] [Indexed: 01/23/2023] Open
Abstract
Chronic compression of dorsal root ganglion (CCD) results in neuropathic pain. We investigated the role of spinal GABA in CCD-induced pain using rats with unilateral CCD. A stereological analysis revealed that the proportion of GABA-immunoreactive neurons to total neurons at L4/5 laminae I-III on the injured side decreased in the early phase of CCD (post-CCD week 1) and then returned to the sham-control level in the late phase (post-CCD week 18). In the early phase, the rats showed an increase in both mechanical sensitivity of the hind paw and spinal WDR neuronal excitability on the injured side, and such increase was suppressed by spinally applied muscimol (GABA-A agonist, 5 nmol) and baclofen (GABA-B agonist, 25 nmol), indicating the reduced spinal GABAergic inhibition involved. In the late phase, the CCD-induced increase in mechanical sensitivity and neuronal excitability returned to pre-CCD levels, and such recovered responses were enhanced by spinally applied bicuculline (GABA-A antagonist, 15 nmol) and CGP52432 (GABA-B antagonist, 15 nmol), indicating the regained spinal GABAergic inhibition involved. In conclusion, the alteration of spinal GABAergic inhibition following CCD and leading to a gradual reduction over time of CCD-induced mechanical hypersensitivity is most likely due to changes in GABA content in spinal GABA neurons.
Collapse
|
43
|
Wang T, Hurwitz O, Shimada SG, Qu L, Fu K, Zhang P, Ma C, LaMotte RH. Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice. PLoS One 2015; 10:e0137512. [PMID: 26356638 PMCID: PMC4565551 DOI: 10.1371/journal.pone.0137512] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/18/2015] [Indexed: 11/29/2022] Open
Abstract
Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli.
Collapse
Affiliation(s)
- Tao Wang
- Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Neuroscience Center, Department of Anatomy, Histology and Embryology, Beijing, China
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Olivia Hurwitz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Steven G. Shimada
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Lintao Qu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University, Baltimore, Maryland
| | - Kai Fu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Pu Zhang
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Chao Ma
- Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Neuroscience Center, Department of Anatomy, Histology and Embryology, Beijing, China
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Robert H. LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
44
|
Inhibition of Hyperpolarization-Activated Cation Current in Medium-Sized DRG Neurons Contributed to the Antiallodynic Effect of Methylcobalamin in the Rat of a Chronic Compression of the DRG. Neural Plast 2015; 2015:197392. [PMID: 26101670 PMCID: PMC4460234 DOI: 10.1155/2015/197392] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/23/2015] [Accepted: 03/23/2015] [Indexed: 02/05/2023] Open
Abstract
Recently several lines of evidence demonstrated that methylcobalamin (MeCbl) might have potential analgesic effect in experimental and clinical studies. However, it was reported that MeCbl had no effect on treating lumbar spinal stenosis induced pain. Thus, the effects of short-term and long-term administration of MeCbl were examined in the chronic compression of dorsal root ganglion (CCD) model. We found that mechanical allodynia was significantly inhibited by a continuous application of high dose and a single treatment of a super high dose of MeCbl. Little is known about mechanisms underlying the analgesia of MeCbl. We examined the effect of MeCbl on the spontaneous activity (SA), the excitability, and hyperpolarization-activated nonselective cation ion current in compressed medium-sized dorsal root ganglion (DRG) neurons using extracellular single fiber recording in vivo and whole-cell patch clamp in vitro. We found that MeCbl significantly inhibited the SA of A-type sensory neurons in a dose-dependent manner and inhibited the excitability of medium-sized DRG neurons. In addition, MeCbl also decreased Ih current density in injured medium-sized DRG neurons. Our results proved that MeCbl might exert an analgesic effect through the inhibition Ih current and then might inhibit the hyperexcitability of primary sensory neurons under neuropathic pain state.
Collapse
|
45
|
Xie W, Strong JA, Zhang JM. Local knockdown of the NaV1.6 sodium channel reduces pain behaviors, sensory neuron excitability, and sympathetic sprouting in rat models of neuropathic pain. Neuroscience 2015; 291:317-30. [PMID: 25686526 DOI: 10.1016/j.neuroscience.2015.02.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 01/21/2015] [Accepted: 02/05/2015] [Indexed: 11/15/2022]
Abstract
In the spinal nerve ligation (SNL) model of neuropathic pain, as in other pain models, abnormal spontaneous activity of myelinated sensory neurons occurs early and is essential for establishing pain behaviors and other pathologies. Sympathetic sprouting into the dorsal root ganglion (DRG) is observed after SNL, and sympathectomy reduces pain behavior. Sprouting and spontaneous activity may be mutually reinforcing: blocking neuronal activity reduces sympathetic sprouting, and sympathetic spouts functionally increase spontaneous activity in vitro. However, most studies in this field have used nonspecific methods to block spontaneous activity, methods that also block evoked and normal activity. In this study, we injected small inhibitory (si) RNA directed against the NaV1.6 sodium channel isoform into the DRG before SNL. This isoform can mediate high-frequency repetitive firing, like that seen in spontaneously active neurons. Local knockdown of NaV1.6 markedly reduced mechanical pain behaviors induced by SNL, reduced sympathetic sprouting into the ligated sensory ganglion, and blocked abnormal spontaneous activity and other measures of hyperexcitability in myelinated neurons in the ligated sensory ganglion. Immunohistochemical experiments showed that sympathetic sprouting preferentially targeted NaV1.6-positive neurons. Under these experimental conditions, NaV1.6 knockdown did not prevent or strongly alter single evoked action potentials, unlike previous less specific methods used to block spontaneous activity. NaV1.6 knockdown also reduced pain behaviors in another pain model, chronic constriction of the sciatic nerve, provided the model was modified so that the lesion site was relatively close to the siRNA-injected lumbar DRGs. The results highlight the relative importance of abnormal spontaneous activity in establishing both pain behaviors and sympathetic sprouting, and suggest that the NaV1.6 isoform may have value as a therapeutic target.
Collapse
Affiliation(s)
- W Xie
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0531, USA.
| | - J A Strong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0531, USA.
| | - J-M Zhang
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0531, USA.
| |
Collapse
|
46
|
Uhelski ML, Khasabova IA, Simone DA. Inhibition of anandamide hydrolysis attenuates nociceptor sensitization in a murine model of chemotherapy-induced peripheral neuropathy. J Neurophysiol 2014; 113:1501-10. [PMID: 25505113 DOI: 10.1152/jn.00692.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Painful neuropathy frequently develops as a consequence of commonly used chemotherapy agents for cancer treatment and is often a dose-limiting side effect. Currently available analgesic treatments are often ineffective on pain induced by neurotoxicity. Although peripheral administration of cannabinoids, endocannabinoids, and inhibitors of endocannabinoid hydrolysis has been effective in reducing hyperalgesia in models of peripheral neuropathy, including chemotherapy-induced peripheral neuropathy (CIPN), few studies have examined cannabinoid effects on responses of nociceptors in vivo. In this study we determined whether inhibition of fatty acid amide hydrolase (FAAH), which slows the breakdown of the endocannabinoid anandamide (AEA), reduced sensitization of nociceptors produced by chemotherapy. Over the course of a week of daily treatments, mice treated with the platinum-based chemotherapy agent cisplatin developed robust mechanical allodynia that coincided with sensitization of cutaneous C-fiber nociceptors as indicated by the development of spontaneous activity and increased responses to mechanical stimulation. Administration of the FAAH inhibitor URB597 into the receptive field of sensitized C-fiber nociceptors decreased spontaneous activity, increased mechanical response thresholds, and decreased evoked responses to mechanical stimuli. Cotreatment with CB1 (AM281) or CB2 (AM630) receptor antagonists showed that the effect of URB597 was mediated primarily by CB1 receptors. These changes following URB597 were associated with an increase in the endocannabinoid anandamide in the skin. Our results suggest that enhanced signaling in the peripheral endocannabinoid system could be utilized to reduce nociceptor sensitization and pain associated with CIPN.
Collapse
Affiliation(s)
- Megan L Uhelski
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota
| | - Iryna A Khasabova
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota
| | - Donald A Simone
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota
| |
Collapse
|
47
|
Blocking the mineralocorticoid receptor improves effectiveness of steroid treatment for low back pain in rats. Anesthesiology 2014; 121:632-43. [PMID: 24781496 DOI: 10.1097/aln.0000000000000277] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Localized inflammation of lumbar dorsal root ganglia (DRG) may contribute to low back pain. Local injections of corticosteroids used for low back pain are sometimes ineffective. Many corticosteroids activate not only the target glucocorticoid receptor (GR) but also the mineralocorticoid receptor (MR), which may have proinflammatory effects countering the effects of GR activation. METHODS A low back pain model was implemented in rats (n = 6 to 10 per group) by locally inflaming the L5 DRG. Sensory neuron excitability and mechanical hypersensitivity of the hind paws were measured. Tested steroids were applied locally to the inflamed DRG or orally. RESULTS The selective MR blocker eplerenone reduced pain behaviors when given orally starting at the time of surgery, or starting 7 days later. The highly GR-selective agonist fluticasone, applied locally to the inflamed DRG, was much more effective in reducing mechanical hypersensitivity. The MR/GR agonist 6-α methylprednisolone, commonly injected for low back pain, reduced mechanical hypersensitivity when applied locally to the DRG but was less effective than fluticasone. Its effectiveness was improved by combining it with local eplerenone. All tested steroids reduced hyperexcitability of myelinated sensory neurons (n = 71 to 220 cells per group) after inflammation, particularly abnormal spontaneous activity. CONCLUSIONS This preclinical study indicates the MR may play an important role in low back pain involving inflammation. Some MR effects may occur at the level of the sensory neuron. It may be useful to consider the action of clinically used steroids at the MR as well as at the GR.
Collapse
|
48
|
Allette YM, Due MR, Wilson SM, Feldman P, Ripsch MS, Khanna R, White FA. Identification of a functional interaction of HMGB1 with Receptor for Advanced Glycation End-products in a model of neuropathic pain. Brain Behav Immun 2014; 42:169-77. [PMID: 25014009 PMCID: PMC4560334 DOI: 10.1016/j.bbi.2014.06.199] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 06/25/2014] [Accepted: 06/27/2014] [Indexed: 10/25/2022] Open
Abstract
Recent studies indicate that the release of high mobility group box 1 (HMGB1) following nerve injury may play a central role in the pathogenesis of neuropathic pain. HMGB1 is known to influence cellular responses within the nervous system via two distinct receptor families; the Receptor for Advanced Glycation End-products (RAGE) and Toll-like receptors (TLRs). The degree to which HMGB1 activates a receptor is thought to be dependent upon the oxidative state of the ligand, resulting in the functional isoforms of all-thiol HMGB1 (at-HMGB1) acting through RAGE, and disufide HMGB1 (ds-HMGB1) interacting with TLR4. Though it is known that dorsal root ganglia (DRG) sensory neurons exposed to HMGB1 and TLR4 agonists can influence excitation, the degree to which at-HMGB1 signaling through neuronal RAGE contributes to neuropathic pain is unknown. Here we demonstrate that at-HMGB1 activation of nociceptive neurons is dependent on RAGE and not TLR4. To distinguish the possible role of RAGE on neuropathic pain, we characterized the changes in RAGE mRNA expression up to one month after tibial nerve injury (TNI). RAGE mRNA expression in lumbar dorsal root ganglion (DRG) is substantially increased by post-injury day (PID) 28 when compared with sham injured rodents. Protein expression at PID28 confirms this injury-induced event in the DRG. Moreover, a single exposure to monoclonal antibody to RAGE (RAGE Ab) failed to abrogate pain behavior at PID 7, 14 and 21. However, RAGE Ab administration produced reversal of mechanical hyperalgesia on PID28. Thus, at-HMGB1 activation through RAGE may be responsible for sensory neuron sensitization and mechanical hyperalgesia associated with chronic neuropathic pain states.
Collapse
Affiliation(s)
- Yohance M Allette
- Medical Science Training Program, Department of Anatomy, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Michael R Due
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Sarah M Wilson
- Program in Medical Neurosciences, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Polina Feldman
- Program in Medical Neurosciences, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Matthew S Ripsch
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Rajesh Khanna
- Program in Medical Neurosciences, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States; Department of Pharmacology and Toxicology, United States; Department of Biochemistry and Molecular Biology, United States
| | - Fletcher A White
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, United States; Program in Medical Neurosciences, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States.
| |
Collapse
|
49
|
Enhanced excitability of primary sensory neurons and altered gene expression of neuronal ion channels in dorsal root ganglion in paclitaxel-induced peripheral neuropathy. Anesthesiology 2014; 120:1463-75. [PMID: 24534904 DOI: 10.1097/aln.0000000000000176] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The mechanism of chemotherapy-induced peripheral neuropathy after paclitaxel treatment is not well understood. Given the poor penetration of paclitaxel into central nervous system, peripheral nervous system is most at risk. METHODS Intrinsic membrane properties of dorsal root ganglion neurons were studied by intracellular recordings. Multiple-gene real-time polymerase chain reaction array was used to investigate gene expression of dorsal root ganglion neuronal ion channels. RESULTS Paclitaxel increased the incidence of spontaneous activity from 4.8 to 27.1% in large-sized and from 0 to 33.3% in medium-sized neurons. Paclitaxel decreased the rheobase (nA) from 1.6 ± 0.1 to 0.8 ± 0.1 in large-sized, from 1.5 ± 0.2 to 0.6 ± 0.1 in medium-sized, and from 1.6 ± 0.2 to 1.0 ± 0.1 in small-sized neurons. After paclitaxel treatment, other characteristics of membrane properties in each group remained the same except that Aδ neurons showed shorter action potential fall time (ms) (1.0 ± 0.2, n = 10 vs. 1.8 ± 0.3, n = 9, paclitaxel vs. vehicle). Meanwhile, real-time polymerase chain reaction array revealed an alteration in expression of some neuronal ion channel genes including up-regulation of hyperpolarization-activated cyclic nucleotide-gated channel 1 (fold change 1.76 ± 0.06) and Nav1.7 (1.26 ± 0.02) and down-regulation of Kir channels (Kir1.1, 0.73 ± 0.05, Kir3.4, 0.66 ± 0.06) in paclitaxel-treated animals. CONCLUSION The increased neuronal excitability and the changes in gene expression of some neuronal ion channels in dorsal root ganglion may provide insight into the molecular and cellular basis of paclitaxel-induced neuropathy, which may lead to novel therapeutic strategies.
Collapse
|
50
|
Menichella DM, Abdelhak B, Ren D, Shum A, Frietag C, Miller RJ. CXCR4 chemokine receptor signaling mediates pain in diabetic neuropathy. Mol Pain 2014; 10:42. [PMID: 24961298 PMCID: PMC4078021 DOI: 10.1186/1744-8069-10-42] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 06/18/2014] [Indexed: 12/31/2022] Open
Abstract
Background Painful Diabetic Neuropathy (PDN) is a debilitating syndrome present in a quarter of diabetic patients that has a substantial impact on their quality of life. Despite this significant prevalence and impact, current therapies for PDN are only partially effective. Moreover, the cellular mechanisms underlying PDN are not well understood. Neuropathic pain is caused by a variety of phenomena including sustained excitability in sensory neurons that reduces the pain threshold so that pain is produced in the absence of appropriate stimuli. Chemokine signaling has been implicated in the pathogenesis of neuropathic pain in a variety of animal models. We therefore tested the hypothesis that chemokine signaling mediates DRG neuronal hyperexcitability in association with PDN. Results We demonstrated that intraperitoneal administration of the specific CXCR4 antagonist AMD3100 reversed PDN in two animal models of type II diabetes. Furthermore DRG sensory neurons acutely isolated from diabetic mice displayed enhanced SDF-1 induced calcium responses. Moreover, we demonstrated that CXCR4 receptors are expressed by a subset of DRG sensory neurons. Finally, we observed numerous CXCR4 expressing inflammatory cells infiltrating into the DRG of diabetic mice. Conclusions These data suggest that CXCR4/SDF-1 signaling mediates enhanced calcium influx and excitability in DRG neurons responsible for PDN. Simultaneously, CXCR4/SDF-1 signaling may coordinate inflammation in diabetic DRG that could contribute to the development of pain in diabetes. Therefore, targeting CXCR4 chemokine receptors may represent a novel intervention for treating PDN.
Collapse
Affiliation(s)
- Daniela Maria Menichella
- Department of Neurology, Robert Lurie Medical Research Center, Northwestern University, Lurie 8-123, 303 E, Superior St, Chicago, IL, USA.
| | | | | | | | | | | |
Collapse
|