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Michels T, Ahmadi S, Graf N. Treatment of peripheral pain with low-dose local anesthetics by epidermal, epithelial and periosteal application. Local Reg Anesth 2018; 11:129-136. [PMID: 30588085 PMCID: PMC6294063 DOI: 10.2147/lra.s151316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Objectives The efficiency of local anesthetics (LAs) in the treatment of peripheral pain is commonly attributed to their capacity to block the axon conduction of sensory nerves. LAs even in non-blocking concentration suppress oscillations of the resting membrane potential. Spiking in sensory neurons is triggered by subthreshold membrane potential oscillations (SMPOs), which reach threshold and is maintained by depolarizing impulse after oscillations. The suppression of these oscillations abolishes sustained afferent discharge in sensory nerves without blocking the axon conduction. In a retrospective observational study, we examined if LAs in low concentration and very small quantities could reduce peripheral pain in patients. Design During a period of 2 years, a total of 127 consecutive patients, 43 with cervico-brachial, 12 with intercostal and 72 with lumbo-sciatic pain received an identical treatment, which consisted of LAs applied in 4–8 sessions on average to a fixed set of epidermal, epithelial and periosteal locations. The primary outcome was relief of symptoms measured by verbal analog scales at the end of therapy. Results At the end of therapy, 53 (41.7%) of all patients (127) had a complete remission (reduction of pain 100%). Twenty-three patients (18.1%) had a partial remission with >90% reduction of pain and 50 patients (39.4%) had a pain reduction of 30%–90%. One patient did not respond. Conclusion LAs in low concentration and small quantities proved to be highly efficient in the treatment of peripheral pain. An almost complete remission could be obtained in a majority of patients. Given the extent of pain reduction achieved, the method of application seems to be of major importance.
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Affiliation(s)
| | - Seifollah Ahmadi
- Institute of Physiology II, University of Bonn, 53115 Bonn, Germany
| | - Nicole Graf
- Graf Biostatistics, CH-8400 Winterthur, Switzerland
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Zhu YF, Kwiecien JM, Dabrowski W, Ungard R, Zhu KL, Huizinga JD, Henry JL, Singh G. Cancer pain and neuropathic pain are associated with A β sensory neuronal plasticity in dorsal root ganglia and abnormal sprouting in lumbar spinal cord. Mol Pain 2018; 14:1744806918810099. [PMID: 30324862 PMCID: PMC6243409 DOI: 10.1177/1744806918810099] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Evidence suggests that there are both nociceptive and neuropathic components of cancer-induced pain. We have observed that changes in intrinsic membrane properties and excitability of normally non-nociceptive Aβ sensory neurons are consistent in rat models of peripheral neuropathic pain and cancer-induced pain. This has prompted a comparative investigation of the intracellular electrophysiological characteristics of sensory neurons and of the ultrastructural morphology of the dorsal horn in rat models of neuropathic pain and cancer-induced pain. Neuropathic pain model rats were induced with a polyethylene cuff implanted around a sciatic nerve. Cancer-induced pain model rats were induced with mammary rat metastasis tumour-1 rat breast cancer or MATLyLu rat prostate cancer cells implanted into the distal epiphysis of a femur. Behavioural evidence of nociception was detected using von Frey tactile assessment. Aβ-fibre low threshold mechanoreceptor neurons in both cancer-induced pain and neuropathic pain models exhibited slower dynamics of action potential genesis, including a wider action potential duration and lower action potential amplitude compared to those in control animals. Enhanced excitability of Aβ-fibre low threshold mechanoreceptor neurons was also observed in cancer-induced pain and neuropathic pain models. Furthermore, both cancer-induced pain and neuropathic pain models showed abundant abnormal axonal sprouting in bundles of myelinated axons in the ipsilateral spinal laminae IV and V. The patterns of changes show consistency between rat models of cancer-induced pain and neuropathic pain. These findings add to the body of evidence that animal models of cancer-induced pain and neuropathic pain share features that may contribute to the peripheral and central sensitization and tactile hypersensitivity in both pain states.
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Affiliation(s)
- Yong Fang Zhu
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jacek M Kwiecien
- 2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,3 Department of Clinical Pathomorphology, Medical University of Lublin, Lublin, Poland
| | - Wojciech Dabrowski
- 4 Department of Anaesthesiology and Intensive Therapy, Medical University of Lublin, Lublin, Poland
| | - Robert Ungard
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Kan Lun Zhu
- 2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jan D Huizinga
- 5 Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - James L Henry
- 6 Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Gurmit Singh
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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3
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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.
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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
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Dilute lidocaine suppresses ectopic neuropathic discharge in dorsal root ganglia without blocking axonal propagation: a new approach to selective pain control. Pain 2018. [DOI: 10.1097/j.pain.0000000000001205] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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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.
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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.
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6
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Pharmacokinetic/Pharmacodynamic Relationship of Gabapentin in a CFA-induced Inflammatory Hyperalgesia Rat Model. Pharm Res 2016; 33:1133-43. [DOI: 10.1007/s11095-016-1859-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/11/2016] [Indexed: 11/25/2022]
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7
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Kukkar A, Bali A, Singh N, Jaggi AS. Implications and mechanism of action of gabapentin in neuropathic pain. Arch Pharm Res 2013; 36:237-51. [PMID: 23435945 DOI: 10.1007/s12272-013-0057-y] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/14/2012] [Indexed: 01/25/2023]
Abstract
Gabapentin is an anti-epileptic agent but now it is also recommended as first line agent in neuropathic pain, particularly in diabetic neuropathy and post herpetic neuralgia. α2δ-1, an auxillary subunit of voltage gated calcium channels, has been documented as its main target and its specific binding to this subunit is described to produce different actions responsible for pain attenuation. The binding to α2δ-1 subunits inhibits nerve injury-induced trafficking of α1 pore forming units of calcium channels (particularly N-type) from cytoplasm to plasma membrane (membrane trafficking) of pre-synaptic terminals of dorsal root ganglion (DRG) neurons and dorsal horn neurons. Furthermore, the axoplasmic transport of α2δ-1 subunits from DRG to dorsal horns neurons in the form of anterograde trafficking is also inhibited in response to gabapentin administration. Gabapentin has also been shown to induce modulate other targets including transient receptor potential channels, NMDA receptors, protein kinase C and inflammatory cytokines. It may also act on supra-spinal region to stimulate noradrenaline mediated descending inhibition, which contributes to its anti-hypersensitivity action in neuropathic pain.
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Affiliation(s)
- Ankesh Kukkar
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, Punjab, India
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8
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Gabapentin reduces allodynia and hyperalgesia in painful diabetic neuropathy rats by decreasing expression level of Nav1.7 and p-ERK1/2 in DRG neurons. Brain Res 2013. [DOI: 10.1016/j.brainres.2012.11.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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9
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Arcos M, Palanca JM, Montes F, Barrios C. Antioxidants and Gabapentin Prevent Heat Hypersensitivity in a Neuropathic Pain Model. J INVEST SURG 2012; 26:109-17. [DOI: 10.3109/08941939.2012.713444] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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10
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Zhu YF, Wu Q, Henry JL. Changes in functional properties of A-type but not C-type sensory neurons in vivo in a rat model of peripheral neuropathy. J Pain Res 2012; 5:175-92. [PMID: 22792004 PMCID: PMC3392709 DOI: 10.2147/jpr.s26367] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background The aim of this study was to compare primary sensory neurons in controls and in an animal neuropathic pain model in order to understand which types of neurons undergo changes associated with peripheral neuropathy. On the basis of intracellular recordings in vivo from somata, L4 sensory dorsal root ganglion neurons were categorized according to action potential configuration, conduction velocity, and receptive field properties to mechanical stimuli. Methods Intracellular recordings were made from functionally identified dorsal root ganglion neurons in vivo in the Mosconi and Kruger animal model of peripheral neuropathic pain. Results In this peripheral neuropathy model, a specific population of Aβ-fiber low threshold mechanoreceptor neurons, which respond normally to innocuous mechanical stimuli, exhibited differences in action potential configuration and conduction velocity when compared with control animals. No abnormal conduction velocity, action potential shapes, or tactile sensitivity of C-fiber neurons were encountered. Conclusion This study provides evidence for defining a potential role of Aβ-fiber low threshold mechanoreceptor neurons that might contribute to peripheral neuropathic pain.
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Affiliation(s)
- Yong Fang Zhu
- Michael G DeGroote Institute for Pain Research and Care, Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
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11
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Waxman SG. Sodium channels, the electrogenisome and the electrogenistat: lessons and questions from the clinic. J Physiol 2012; 590:2601-12. [PMID: 22411010 DOI: 10.1113/jphysiol.2012.228460] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the six decades that have followed the work of Hodgkin and Huxley, multiple generations of neuroscientists and biophysicists have built upon their pivotal contributions. It is now clear that, in mammals, nine genes encode nine distinct voltage-gated sodium channels with different amino acid sequences and different physiological and pharmacological properties. The different sodium channel isoforms produce a multiplicity of distinct sodium currents with different time-dependent characteristics and voltage dependencies, which interact with each other and with the currents produced by other channels (including calcium and potassium channels) to shape neuronal firing patterns. Expression of these sodium channel isoforms is highly dynamic, both in the normal nervous system, and in the injured nervous system. Recent research has shed light on the roles of sodium channels in human disease, a development that may open up new therapeutic strategies. This article examines the pain-signalling system as an example of a neuronal network where multiple sodium channel isoforms play complementary roles in electrogenesis and a strong link with human disease has been established. Recent research suggests that it may be possible to target specific sodium channel isoforms that drive hyperexcitability in pain-signalling neurons, thereby providing new therapeutic strategies for chronic pain, and providing an illustration of the impact of the Hodgkin-Huxley legacy in the clinical domain.
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Affiliation(s)
- Stephen G Waxman
- Department of Neurology and Centre for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.
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12
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Evoked bursting in injured Aβ dorsal root ganglion neurons: A mechanism underlying tactile allodynia. Pain 2012; 153:657-665. [DOI: 10.1016/j.pain.2011.11.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 11/28/2011] [Accepted: 11/29/2011] [Indexed: 11/17/2022]
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13
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Effects of Gabapentin on Different Neuronal Populations in the Dorsal-Root Ganglia of Rats with Streptozotocin-Induced Diabetes Mellitus. NEUROPHYSIOLOGY+ 2009. [DOI: 10.1007/s11062-009-9084-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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Yang RH, Wang WT, Chen JY, Xie RG, Hu SJ. Gabapentin selectively reduces persistent sodium current in injured type-A dorsal root ganglion neurons. Pain 2009; 143:48-55. [DOI: 10.1016/j.pain.2009.01.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 12/12/2008] [Accepted: 01/16/2009] [Indexed: 11/25/2022]
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15
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Devor M. Ectopic discharge in Abeta afferents as a source of neuropathic pain. Exp Brain Res 2009; 196:115-28. [PMID: 19242687 DOI: 10.1007/s00221-009-1724-6] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 01/22/2009] [Indexed: 12/25/2022]
Abstract
Ectopic discharge in axotomized dorsal root ganglion neurons is a key driver of neuropathic pain. However, the bulk of this activity is generated and carried centrally in large diameter myelinated Abeta afferents, a cell type that normally signals touch and vibration sense. Evidence is considered suggesting that following axotomy, Abeta afferents undergo a change in their electrical characteristics and also in the neurotransmitter complement that they express. This dual phenotypic switching renders them capable of (1) directly driving postsynaptic pain signaling pathways in the spinal cord, and (2) triggering and maintaining central sensitization.
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Affiliation(s)
- Marshall Devor
- Department of Cell and Developmental Biology, Institute of Life Sciences and Center for Research on Pain, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
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16
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Romanenko SV, Kostyuk PG, Kostyuk EP. Effects of Gabapentin on Calcium Transients in Neurons of the Rat Dorsal Root Ganglia. NEUROPHYSIOLOGY+ 2009. [DOI: 10.1007/s11062-009-9049-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Roberto M, Gilpin NW, O'Dell LE, Cruz MT, Morse AC, Siggins GR, Koob GF. Cellular and behavioral interactions of gabapentin with alcohol dependence. J Neurosci 2008; 28:5762-71. [PMID: 18509038 PMCID: PMC2493536 DOI: 10.1523/jneurosci.0575-08.2008] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 04/21/2008] [Accepted: 04/21/2008] [Indexed: 11/21/2022] Open
Abstract
Gabapentin is a structural analog of GABA that has anticonvulsant properties. Despite the therapeutic efficacy of gabapentin, its molecular and cellular mechanisms of action are unclear. The GABAergic system in the central nucleus of the amygdala (CeA) plays an important role in regulating voluntary ethanol intake. Here, we investigated the effect of gabapentin on GABAergic transmission in CeA slices, on ethanol intake, and on an anxiety measure using animal models of ethanol dependence. Gabapentin increased the amplitudes of evoked GABA receptor-mediated IPSCs (GABA-IPSCs) in CeA neurons from nondependent rats, but decreased their amplitudes in CeA of ethanol-dependent rats. Gabapentin effects were blocked in the presence of a specific GABA(B) receptor antagonist. The sensitivity of the GABA-IPSCs to a GABA(B) receptor antagonist and an agonist was decreased after chronic ethanol, suggesting that ethanol-induced neuroadaptations of GABA(B) receptors associated with ethanol dependence may account for the differential effects of gabapentin after chronic ethanol. Systemic gabapentin reduced ethanol intake in dependent, but not in nondependent, rats and reversed the anxiogenic-like effects of ethanol abstinence using an acute dependence model. Gabapentin infused directly into the CeA also blocked dependence-induced elevation in operant ethanol responding. Collectively, these findings show that gabapentin reverses behavioral measures of ethanol dependence and, in turn, dependence reverses the effects of gabapentin on CeA neurons, and suggest that gabapentin represents a potential medication for treatment of alcoholism.
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Affiliation(s)
- Marisa Roberto
- Committee on the Neurobiology of Addictive Disorders, Pearson Center for Alcoholism and Addiction Research, The Scripps Research Institute, La Jolla, California 92037, USA.
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Johannessen Landmark C. Antiepileptic drugs in non-epilepsy disorders: relations between mechanisms of action and clinical efficacy. CNS Drugs 2008; 22:27-47. [PMID: 18072813 DOI: 10.2165/00023210-200822010-00003] [Citation(s) in RCA: 218] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Antiepileptic drugs (AEDs) are used extensively to treat multiple non-epilepsy disorders, both in neurology and psychiatry. This article provides a review of the clinical efficacy of AEDs in non-epilepsy disorders based on recently published preclinical and clinical studies, and attempts to relate this efficacy to the mechanism of action of AEDs and pathophysiological processes associated with the disorders. Some newer indications for AEDs have been established, while others are under investigation. The disorders where AEDs have been demonstrated to be of clinical importance include neurological disorders, such as essential tremor, neuropathic pain and migraine, and psychiatric disorders, including anxiety, schizophrenia and bipolar disorder. Many of the AEDs have various targets of action in the synapse and have several proposed relevant mechanisms of action in epilepsy and in other disorders. Pathophysiological processes disturb neuronal excitability by modulating ion channels, receptors and intracellular signalling pathways, and these are targets for the pharmacological action of various AEDs. Attention is focused on the glutamatergic and GABAergic synapses. In psychiatric conditions such as schizophrenia and bipolar disorder, AEDs such as valproate, carbamazepine and lamotrigine appear to have clear roles based on their effect on intracellular pathways. On the other hand, some AEDs, e.g. topiramate, have efficacy for nonpsychiatric disorders including migraine, possibly by enhancing GABAergic and reducing glutamatergic neurotransmission. AEDs that seem to enhance GABAergic neurotransmission, e.g. tiagabine, valproate, gabapentin and possibly levetiracetam, may have a role in treating neurological disorders such as essential tremor, or anxiety disorders. AEDs with effects on voltage-gated sodium or calcium channels may be advantageous in treating neuropathic pain, e.g. gabapentin, pregabalin, carbamazepine, oxcarbazepine, lamotrigine and valproate. Co-morbid conditions associated with epilepsy, such as mood disorders and migraine, may often respond to treatment with AEDs. Other possible disorders where AEDs may be of clinical importance include cancer, HIV infection, drug and alcohol abuse, and also in neuroprotection. A future challenge is to evaluate the second-generation AEDs in non-epilepsy disorders and to design clinical trials to study their effects in such disorders in paediatric patients. Differentiation between the main mechanisms of action of the AEDs needs more consideration in drug selection for tailored treatment of the various non-epilepsy disorders.
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Hayashida KI, Clayton BA, Johnson JE, Eisenach JC. Brain derived nerve growth factor induces spinal noradrenergic fiber sprouting and enhances clonidine analgesia following nerve injury in rats. Pain 2007; 136:348-355. [PMID: 17822849 PMCID: PMC2486433 DOI: 10.1016/j.pain.2007.07.014] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/17/2007] [Accepted: 07/23/2007] [Indexed: 01/21/2023]
Abstract
Many treatments for neuropathic pain activate or augment norepinephrine release in the spinal cord, yet these treatments are less effective against acute nociceptive stimuli. We previously showed in mice that peripheral nerve injury results in sprouting of spinal noradrenergic fibers, possibly reflecting the substrate for this shift in drug efficacy. Here, we tested whether such sprouting also occurs in rats after nerve injury and examined one signal for such sprouting. Ligation of L5 and L6 spinal nerves unilaterally in rats resulted in hypersensitivity to tactile stimulation of the ipsilateral paw, and sprouting of noradrenergic fibers in the dorsal horn of the lumbar spinal cord. Brain derived nerve growth factor (BDNF) content increased in L4-L6 dorsal root ganglia ipsilateral to injury and in lumbar spinal cord following nerve injury, and intrathecal infusion of BDNF antiserum prevented spinal noradrenergic sprouting. This treatment also prevented the increased analgesic efficacy of intrathecal clonidine observed after nerve injury. Intraspinal injection of BDNF in non-injured rats mimicked the sprouting of spinal noradrenergic fibers seen after nerve injury. These results suggest that increased BDNF synthesis and release drives spinal noradrenergic sprouting following nerve injury, and that this sprouting may paradoxically increase the capacity for analgesia in the setting of neuropathic pain from drugs which utilize or mimic the noradrenergic pathway.
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Affiliation(s)
- Ken-Ichiro Hayashida
- Department of Anesthesiology and Center for the Pharmacologic Plasticity in the Presence of Pain, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
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20
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Michels T, Lehmann N, Moebus S. Cervical Vertigo—Cervical Pain: An Alternative and Efficient Treatment. J Altern Complement Med 2007; 13:513-8. [PMID: 17604554 DOI: 10.1089/acm.2007.6102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Cervical vertigo (CV) is commonly attributed to a disturbed cervical proprioception and is associated with cervical pain (CP). It is assumed to respond to a treatment that improves CP. In a prospective observational study, we examined whether a treatment originally devised for patients with CP could improve CV also in cases without CP. DESIGN During a period of 3 years, a total of 238 consecutive patients, 41 patients with CV only, 43 patients with CV and CP, 154 patients with CP only, received the same treatment, which consisted of local anaesthetics applied on average in 8 sessions to a fixed set of epidermal, epithelial, and periosteal locations. Outcome was relief of symptoms measured by a verbal-analogue scale at the end of therapy and on average a year later. RESULTS At the end of therapy, 58% of patients with CV responded with complete remissions compared to 41% of patients with CP. At follow-up a year later, there were complete remissions in more than 50% in CV as well as in CP. CONCLUSIONS The applied therapy led to complete remissions of long duration in a high percentage of patients with CV even when symptoms of CP were missing. This therapy produced good effects for CP as well. Its neurophysiological basis is discussed and may offer a new approach not only to the treatment of CV and CP but in a general sense also to that of acute, chronic, and neuropathic pain. It needs to be emphasized, however, that this study was not a randomized controlled trial and its encouraging results have to be proved by further research.
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Affiliation(s)
- Thomas Michels
- Practice for Internal Medicine, Hematology, Radiology, Natural Cure, Cologne (Köln), Germany.
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21
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Lee HJ, Shin SW, Jang HJ. The Combined Antiallodynic Effect of Gabapentin and Milnacipran in a Rat Neuropathic Pain Model. Korean J Pain 2007. [DOI: 10.3344/kjp.2007.20.1.8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Hyoen Jeong Lee
- Department of Anesthesia and Pain Medicine, Pusan National University, Busan, Korea
| | - Sang-Wook Shin
- Department of Anesthesia and Pain Medicine, Pusan National University, Busan, Korea
| | - Hee Jeong Jang
- Department of Anesthesia and Pain Medicine, Pusan National University, Busan, Korea
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Abstract
UNLABELLED Na+ channels are large transmembrane proteins with a voltage-gated central pore capable of selectively passing Na+ ions. They are critical determinants of the electrical excitability of sensory neurons and play a key role in pain sensation by controlling afferent impulse discharge. Injury and disease affecting peripheral nerves induces axonopathy and demyelination. These neuropathic changes, in turn, trigger membrane remodeling in injured afferents and perhaps also in uninjured neighbors. A major consequence of the remodeling is increased cellular excitability. This is due in large part to subtype-selective abnormalities in the expression and trafficking of Na+ channels and perhaps also to altered kinetic properties of unitary channels. Hyperexcitable neurons show enhanced membrane resonance, rhythmogenesis, and ectopic spiking. The resulting excess discharge constitutes a primary neuropathic pain signal. In addition, it triggers and maintains central sensitization. This amplifies residual afferent input, yielding tactile allodynia, and it also amplifies ongoing ectopia that exaggerates spontaneous pain. Membrane-stabilizing Na+ channel ligands suppress neuropathic pain by selectively reducing membrane resonance in injured afferents and hence ectopic hyperexcitability. The clinical usefulness of these peripherally acting drugs might be enhanced by reducing their central side effects. PERSPECTIVE Neuropathic pain is a complex outcome of multiple pathophysiological changes that develop in the peripheral nervous system (PNS) and the central nervous system (CNS) following nerve injury or disease. All or most of the CNS changes are thought to be due to abnormal signaling from the PNS, notably electrical hyperexcitability of peripheral sensory neurons. Because hyperexcitability is associated with abnormal sodium channel regulation, this process is a prime target for therapeutic intervention.
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Affiliation(s)
- Marshall Devor
- Department of Cell & Animal Biology, Institute of Life Sciences and Center for Research on Pain, Hebrew University of Jerusalem, Jerusalem, Israel.
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23
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Suzuki R, Dickenson AH. Differential pharmacological modulation of the spontaneous stimulus-independent activity in the rat spinal cord following peripheral nerve injury. Exp Neurol 2005; 198:72-80. [PMID: 16336968 DOI: 10.1016/j.expneurol.2005.10.032] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 10/07/2005] [Accepted: 10/31/2005] [Indexed: 10/25/2022]
Abstract
Peripheral nerve injury is a significant clinical problem that is often difficult to treat. The major clinical symptoms are numbness, tactile and cooling allodynia, hyperalgesias as well as ongoing pain. In animal models of neuropathy, abnormal responses to applied (or evoked) stimuli can be gauged, but spontaneous pain, a major clinical issue, has proved very difficult to assess. In neuropathic animals, spinal neuronal hyperexcitability indicative of peripheral and central changes with high levels of spontaneous neuronal firing has been reported. This latter stimulus-independent firing of sensory neurones may be a measure related to ongoing pain. Two weeks after L5/6 spinal nerve ligation, deep dorsal horn neurones were recorded in halothane-anesthetized rats. The majority of neurones in neuropathic rats showed increased levels of spontaneous firing with irregular firing patterns. We examined and compared the effects of 5 centrally acting pharmacological agents: morphine (i.t. or i.v.), gabapentin, ketamine, memantine and mepyramine on stimulus-independent neuronal firing. This ongoing activity showed high sensitivity to gabapentin (s.c.) and morphine (i.t.) administration, being significantly reduced in a dose-dependent manner. Morphine administered via the systemic route produced modest but non-significant reductions of spontaneous activity. The two NMDA receptor antagonists, ketamine and memantine, and the histamine H1 receptor antagonist, mepyramine, produced minor effects at doses known to be effective on stimulus evoked measures of deep dorsal horn neurones. This may form an electrophysiological basis for the efficacy of gabapentin and spinal morphine on ongoing pain in patients with peripheral neuropathy.
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Affiliation(s)
- Rie Suzuki
- Department of Pharmacology, Medical Sciences Building, University College London, Gower Street, London WC1E 6BT, UK.
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