1
|
Damo E, Agarwal A, Simonetti M. Activation of β2-Adrenergic Receptors in Microglia Alleviates Neuropathic Hypersensitivity in Mice. Cells 2023; 12:cells12020284. [PMID: 36672219 PMCID: PMC9856373 DOI: 10.3390/cells12020284] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/22/2022] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Drugs enhancing the availability of noradrenaline are gaining prominence in the therapy of chronic neuropathic pain. However, underlying mechanisms are not well understood, and research has thus far focused on α2-adrenergic receptors and neuronal excitability. Adrenergic receptors are also expressed on glial cells, but their roles toward antinociception are not well deciphered. This study addresses the contribution of β2-adrenergic receptors (β2-ARs) to the therapeutic modulation of neuropathic pain in mice. We report that selective activation of β2-ARs with Formoterol inhibits pro-inflammatory signaling in microglia ex vivo and nerve injury-induced structural remodeling and functional activation of microglia in vivo. Systemic delivery of Formoterol inhibits behaviors related to neuropathic pain, such as mechanical hypersensitivity, cold allodynia as well as the aversive component of pain, and reverses chronically established neuropathic pain. Using conditional gene targeting for microglia-specific deletion of β2-ARs, we demonstrate that the anti-allodynic effects of Formoterol are primarily mediated by microglia. Although Formoterol also reduces astrogliosis at late stages of neuropathic pain, these functions are unrelated to β2-AR signaling in microglia. Our results underline the value of developing microglial β2-AR agonists for relief from neuropathic pain and clarify mechanistic underpinnings.
Collapse
Affiliation(s)
- Elisa Damo
- Institute of Pharmacology, Medical Faculty Heidelberg, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Amit Agarwal
- The Chica and Heinz Schaller Research Group, Institute of Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Manuela Simonetti
- Institute of Pharmacology, Medical Faculty Heidelberg, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
- Correspondence:
| |
Collapse
|
2
|
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
|
3
|
Matsushita Y, Manabe M, Kitamura N, Shibuya I. Adrenergic receptors inhibit TRPV1 activity in the dorsal root ganglion neurons of rats. PLoS One 2018; 13:e0191032. [PMID: 29304162 PMCID: PMC5755923 DOI: 10.1371/journal.pone.0191032] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/26/2017] [Indexed: 11/18/2022] Open
Abstract
Transient receptor potential vanilloid type 1 (TRPV1) is a polymodal receptor channel that responds to multiple types of stimuli, such as heat, acid, mechanical pressure and some vanilloids. Capsaicin is the most commonly used vanilloid to stimulate TRPV1. TRPV1 channels are expressed in dorsal root ganglion neurons that extend to Aδ- and C-fibers and have a role in the transduction of noxious inputs to the skin into the electrical signals of the sensory nerve. Although noradrenergic nervous systems, including the descending antinociceptive system and the sympathetic nervous system, are known to modulate pain sensation, the functional association between TRPV1 and noradrenaline in primary sensory neurons has rarely been examined. In the present study, we examined the effects of noradrenaline on capsaicin-evoked currents in cultured dorsal root ganglion neurons of the rat by the whole-cell voltage clamp method. Noradrenaline at concentrations higher than 0.1 pM significantly reduced the amplitudes of the inward capsaicin currents recorded at -60 mV holding potential. This inhibitory action was reversed by either yohimbine (an α2 antagonist, 10 nM) or propranolol (a β antagonist, 10 nM). The α2 agonists, clonidine (1 pM) and dexmedetomidine (1 pM) inhibited capsaicin currents, and yohimbine (1 nM) reversed the effects of clonidine. The inhibitory action of noradrenaline was not seen in the neurons pretreated with pertussis toxin (100 μg/ml for 24 h) and the neurons dialyzed intracellularly with guanosine 5'- [β-thio] diphosphate (GDPβS, 200 μM), the catalytic subunit of protein kinase A (250 U/ml) or okadaic acid (1 μM). These results suggest that noradrenaline directly acts on dorsal root ganglion neurons to inhibit the activity of TRPV1 depending on the activation of α2-adrenoceptors followed by the inhibition of the adenylate cyclase/cAMP/protein kinase A pathway.
Collapse
Affiliation(s)
- Yumi Matsushita
- Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Miki Manabe
- Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Naoki Kitamura
- Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University, Tottori, Japan
- * E-mail:
| | - Izumi Shibuya
- Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University, Tottori, Japan
| |
Collapse
|
4
|
Taha O, Opitz T, Mueller M, Pitsch J, Becker A, Evert BO, Beck H, Jeub M. Neuropathic pain in experimental autoimmune neuritis is associated with altered electrophysiological properties of nociceptive DRG neurons. Exp Neurol 2017; 297:25-35. [PMID: 28734788 DOI: 10.1016/j.expneurol.2017.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/02/2017] [Accepted: 07/13/2017] [Indexed: 12/30/2022]
Abstract
Guillain-Barré syndrome (GBS) is an acute, immune-mediated polyradiculoneuropathy characterized by rapidly progressive paresis and sensory disturbances. Moderate to severe and often intractable neuropathic pain is a common symptom of GBS, but its underlying mechanisms are unknown. Pathology of GBS is classically attributed to demyelination of large, myelinated peripheral fibers. However, there is increasing evidence that neuropathic pain in GBS is associated with impaired function of small, unmyelinated, nociceptive fibers. We therefore examined the functional properties of small DRG neurons, the somata of nociceptive fibers, in a rat model of GBS (experimental autoimmune neuritis=EAN). EAN rats developed behavioral signs of neuropathic pain. This was accompanied by a significant shortening of action potentials due to a more rapid repolarization and an increase in repetitive firing in a subgroup of capsaicin-responsive DRG neurons. Na+ current measurements revealed a significant increase of the fast TTX-sensitive current and a reduction of the persistent TTX-sensitive current component. These changes of Na+ currents may account for the significant decrease in AP duration leading to an overall increase in excitability and are therefore possibly directly linked to pathological pain behavior. Thus, like in other animal models of neuropathic and inflammatory pain, Na+ channels seem to be crucially involved in the pathology of GBS and may constitute promising targets for pain modulating pharmaceuticals.
Collapse
Affiliation(s)
- Omneya Taha
- Department of Neurology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany; Department of Epileptology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Thoralf Opitz
- Department of Epileptology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Marcus Mueller
- Department of Neurology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Julika Pitsch
- Department of Neuropathology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Albert Becker
- Department of Neuropathology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Bernd Oliver Evert
- Department of Neurology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Heinz Beck
- Department of Epileptology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany
| | - Monika Jeub
- Department of Neurology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany; Department of Epileptology, University of Bonn Medical Center, Sigmund Freud Straße 25, 53105 Bonn, Germany.
| |
Collapse
|
5
|
Rat model of cancer-induced bone pain: changes in nonnociceptive sensory neurons in vivo. Pain Rep 2017; 2:e603. [PMID: 29392218 PMCID: PMC5741358 DOI: 10.1097/pr9.0000000000000603] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/15/2017] [Accepted: 04/25/2017] [Indexed: 01/31/2023] Open
Abstract
Nonnociceptive sensory neurons relate to transient episodes of intense pain that characterize neuropathic pain. They are involved in the peripheral sensitization and tactile hypersensitivity. Introduction: Clinical data on cancer-induced bone pain (CIBP) suggest extensive changes in sensory function. In a previous investigation of an animal model of CIBP, we have observed that changes in intrinsic membrane properties and excitability of dorsal root ganglion (DRG) nociceptive neurons correspond to mechanical allodynia and hyperalgesia. Objectives: To investigate the mechanisms underlying changes in nonnociceptive sensory neurons in this model, we have compared the electrophysiological properties of primary nonnociceptive sensory neurons at <1 and >2 weeks after CIBP model induction with properties in sham control animals. Methods: Copenhagen rats were injected with 106 MAT-LyLu rat prostate cancer cells into the distal femur epiphysis to generate a model of CIBP. After von Frey tactile measurement of mechanical withdrawal thresholds, the animals were prepared for acute electrophysiological recordings of mechanically sensitive neurons in the DRG in vivo. Results: The mechanical withdrawal threshold progressively decreased in CIBP model rats. At <1 week after model induction, there were no changes observed in nonnociceptive Aβ-fiber DRG neurons between CIBP model rats and sham rats. However, at >2 weeks, the Aβ-fiber low-threshold mechanoreceptors (LTMs) in CIBP model rats exhibited a slowing of the dynamics of action potential (AP) genesis, including wider AP duration and lower AP amplitude compared with sham rats. Furthermore, enhanced excitability of Aβ-fiber LTM neurons was observed as an excitatory discharge in response to intracellular injection of depolarizing current into the soma. Conclusion: After induction of the CIBP model, Aβ-fiber LTMs at >2 weeks but not <1 week had undergone changes in electrophysiological properties. Importantly, changes observed are consistent with observations in models of peripheral neuropathy. Thus, Aβ-fiber nonnociceptive primary sensory neurons might be involved in the peripheral sensitization and tumor-induced tactile hypersensitivity in CIBP.
Collapse
|
6
|
Palinopsia revamped: A systematic review of the literature. Surv Ophthalmol 2015; 60:1-35. [DOI: 10.1016/j.survophthal.2014.06.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/23/2014] [Accepted: 06/24/2014] [Indexed: 02/07/2023]
|
7
|
Lönnqvist PA. Adjuncts should always be used in pediatric regional anesthesia. Paediatr Anaesth 2015; 25:100-6. [PMID: 25230242 DOI: 10.1111/pan.12526] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/15/2014] [Indexed: 02/03/2023]
Abstract
A number of different adjuncts to local anesthetics can be used to prolong and optimize postoperative pain relief following regional anesthesia in children. The present text provides a slightly opinionated but evidence-based argument in favor of this practice.
Collapse
Affiliation(s)
- Per-Arne Lönnqvist
- Paediatric Anaesthesia & Intensive Care, Section of Anaesthesiology & Intensive Care, Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden; Paediatric Anaesthesia, Inetsive Care & ECMO Services, Astrid Lindgrens Children's Hospital/Karolinska University Hospital-Solna, Stockholm, Sweden
| |
Collapse
|
8
|
Lee HG, Choi JI, Kim YO, Yoon MH. The role of alpha-2 adrenoceptor subtype in the antiallodynic effect of intraplantar dexmedetomidine in a rat spinal nerve ligation model. Neurosci Lett 2013; 557 Pt B:118-22. [PMID: 24161890 DOI: 10.1016/j.neulet.2013.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/24/2013] [Accepted: 10/01/2013] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to examine the effects of intraplantar dexmedetomidine to relieve neuropathic pain and determine the role of peripheral α2-adrenoceptors. Neuropathic pain was induced by ligating the L5 and L6 spinal nerves in male Sprague-Dawley rats, and mechanical allodynia was assessed using von Frey filaments. Several antagonists were injected into the hindpaws to evaluate the mechanisms of action of dexmedetomidine, a nonselective α2-adrenoceptor antagonist yohimbine, an α2A-adrenoceptor antagonist BRL 44408, an α2B-adrenoceptor antagonist ARC 239, and a α2C-adrenoceptor antagonist JP 1302. The expression of α2A-adrenoceptor, α2B-adrenoceptor, and α2C-adrenoceptor genes in the lumbar segment of the spinal cord and the plantar skin of the nerve-injured leg was detected by reverse transcription-polymerase chain reaction. Ipsilateral intraplantar injection of dexmedetomidine produced dose-dependent antiallodynia. Ipsilateral, but not contraleral, intraplantar injection of yohimbine reversed the antinociception of dexmedetomidine. Intraplantar BRL 44408, ARC 239, and JP 1302 reversed the antinociception of dexmedetomidine. The expression levels of α2-adrenoceptor genes in the lumbar spinal cord did not differ between rats with neuropathic pain and naïve rats. The expression levels of α2B-adrenoceptor and α2C-adrenoceptor genes of plantar skin were upregulated significantly in the model group, whereas α2A-adrenoceptor expression was unchanged. These results suggest that intraplantar injection of dexmedetomidine produced an antiallodynic effect in spinal nerve ligation-induced neuropathic pain. All three types of peripheral α2A, α2B, and α2C-adrenoceptors were involved in the antiallodynic mechanism of dexmedetomidine.
Collapse
Affiliation(s)
- Hyung Gon Lee
- Department of Anesthesiology and Pain Medicine, Chonnam National University, Medical School, Gwangju, Republic of Korea
| | | | | | | |
Collapse
|
9
|
Pertovaara A. The noradrenergic pain regulation system: A potential target for pain therapy. Eur J Pharmacol 2013; 716:2-7. [DOI: 10.1016/j.ejphar.2013.01.067] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 12/26/2022]
|
10
|
Bosco R, Alvarado S, Quiroz D, Eblen-Zajjur A. Digital Morphometric Characterization of Lumbar Dorsal Root Ganglion Neurons in Rats. J Histotechnol 2013. [DOI: 10.1179/his.2010.33.3.113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
11
|
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.
Collapse
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
| | | | | |
Collapse
|
12
|
Wang YJ, Li XF, Ding F, Shu Q, Song LJ, Yu X, Liu HX. Noradrenaline regulates substance P release from rat dorsal root ganglion neurons in vitro. Neurosci Bull 2012; 27:300-6. [PMID: 21934725 DOI: 10.1007/s12264-011-1034-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE To determine whether activation and/or inhibition of α-adrenoreceptors influences substance P (SP) release from dorsal root ganglion (DRG) primary sensory neurons in vitro. METHODS DRGs were dissected from 15-day embryonic Wistar rats. DRG neurons were dissociated and cultured for 2 d and then exposed to noradrenaline (NA) alone (1×10(-4) mol/L), or along with the α1-adrenoreceptor antagonist prazosin (1×10(-6) mol/L) or the α2-adrenoreceptor antagonist yohimbine (1×10(-5) mol/L) for 4 d. Then, RT-PCR was used to determine the levels of preprotachykinin (PPT) mRNA encoding for SP and Western blot to assess the protein levels of SP. Basal and capsaicin (CAP)-evoked SP release were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS CAP-evoked SP release was sensitized by NA and this effect was inhibited by pre-incubation with prazosin but not with yohimbine. The levels of PPT mRNA, SP peptide, and basal SP release did not change significantly in any of the experimental conditions. CONCLUSION NA may significantly increase CAP-evoked SP release through activation of α-adrenoreceptors, which may contribute to noradrenergic pain modulation.
Collapse
Affiliation(s)
- Yan-Jie Wang
- Department of Rheumatology, Shandong University Qilu Hospital, Jinan 250012, China
| | | | | | | | | | | | | |
Collapse
|
13
|
Tulleuda A, Cokic B, Callejo G, Saiani B, Serra J, Gasull X. TRESK channel contribution to nociceptive sensory neurons excitability: modulation by nerve injury. Mol Pain 2011; 7:30. [PMID: 21527011 PMCID: PMC3095542 DOI: 10.1186/1744-8069-7-30] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/28/2011] [Indexed: 01/01/2023] Open
Abstract
Background Neuronal hyperexcitability is a crucial phenomenon underlying spontaneous and evoked pain. In invertebrate nociceptors, the S-type leak K+ channel (analogous to TREK-1 in mammals) plays a critical role of in determining neuronal excitability following nerve injury. Few data are available on the role of leak K2P channels after peripheral axotomy in mammals. Results Here we describe that rat sciatic nerve axotomy induces hyperexcitability of L4-L5 DRG sensory neurons and decreases TRESK (K2P18.1) expression, a channel with a major contribution to total leak current in DRGs. While the expression of other channels from the same family did not significantly change, injury markers ATF3 and Cacna2d1 were highly upregulated. Similarly, acute sensory neuron dissociation (in vitro axotomy) produced marked hyperexcitability and similar total background currents compared with neurons injured in vivo. In addition, the sanshool derivative IBA, which blocked TRESK currents in transfected HEK293 cells and DRGs, increased intracellular calcium in 49% of DRG neurons in culture. Most IBA-responding neurons (71%) also responded to the TRPV1 agonist capsaicin, indicating that they were nociceptors. Additional evidence of a biological role of TRESK channels was provided by behavioral evidence of pain (flinching and licking), in vivo electrophysiological evidence of C-nociceptor activation following IBA injection in the rat hindpaw, and increased sensitivity to painful pressure after TRESK knockdown in vivo. Conclusions In summary, our results clearly support an important role of TRESK channels in determining neuronal excitability in specific DRG neurons subpopulations, and show that axonal injury down-regulates TRESK channels, therefore contributing to neuronal hyperexcitability.
Collapse
Affiliation(s)
- Astrid Tulleuda
- Neurophysiology Lab, Dept, Physiological Sciences I, Medical School, University of Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
14
|
Transforaminal epidural clonidine versus corticosteroid for acute lumbosacral radiculopathy due to intervertebral disc herniation. Spine (Phila Pa 1976) 2011; 36:E293-300. [PMID: 21192304 PMCID: PMC3052879 DOI: 10.1097/brs.0b013e3181ddd597] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Randomized, double-blinded trial clinical trial. OBJECTIVE To compare efficacies of 2 active therapies for chronic low back pain. SUMMARY OF BACKGROUND DATA Radicular pain may result from intervertebral disk herniation (IDH). Clonidine has demonstrated analgesic and antiinflammatory activity in animal studies of nerve injury. Extensive clinical experience supports neuraxial clonidine's safety. METHODS Patients with ˜3 months of low back and leg pain due to IDH were randomized to transforaminal epidural (TFE) injection(s) of 2% lidocaine and either clonidine (200 or 400mcg) or triamcinolone (40mg). Patients received 1- 3 injections administered about 2 weeks apart. Patients, investigators and study coordinators were blinded to treatment. Primary outcome was 11-point Pain Intensity Numerical Rating Scale (PI-NRS) at 1 month. Other outcomes included Patient Global Impression of Change (PGIC), and functional measures. RESULTS Thirty-three patients were screened and randomized. Twenty-six patients enrolled; 11 received clonidine and 15 triamcinolone. Both groups showed significant improvement in pain score at 2 weeks and 1 month compared to baseline (p< 0.05). The corticosteroid group showed additional functional improvement at 1 month relative to clonidine (p=0.022). There was no difference between groups for primary outcome. However, as target enrollment was not reached, we cannot say with confidence that the 2 treatments would be expected to result in similar short-term pain relief. Side-effects were common in both groups, but there were no serious complications. CONCLUSIONS Radicular pain due to IDH improved rapidly with TFE injection of either clonidine or triamcinolone. Corticosteroid resulted in greater functional improvement, with unclear differences in analgesia. Future studies will determine if clonidine is superior to placebo and of particular use in those at risk for corticosteroid complications.
Collapse
|
15
|
Wu Q, Henry JL. Changes in Abeta non-nociceptive primary sensory neurons in a rat model of osteoarthritis pain. Mol Pain 2010; 6:37. [PMID: 20594346 PMCID: PMC2908067 DOI: 10.1186/1744-8069-6-37] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 07/01/2010] [Indexed: 11/18/2022] Open
Abstract
Background Pain is a major debilitating factor in osteoarthritis (OA), yet few mechanism-based therapies are available. To address the need to understand underlying mechanisms the aim of the present study was to determine changes in sensory neurons in an animal model of OA pain. Results The model displayed typical osteoarthritis pathology characterized by cartilage degeneration in the knee joint and also manifested knee pathophysiology (edema and increased vasculature permeability of the joint) and altered nociception of the affected limb (hind paw tenderness and knee articulation-evoked reduction in the tail flick latency). Neurons included in this report innervated regions throughout the entire hind limb. Aβ-fiber low threshold mechanoreceptors exhibited a slowing of the dynamics of action potential (AP) genesis, including wider AP duration and slower maximum rising rate, and muscle spindle neurons were the most affected subgroup. Only minor AP configuration changes were observed in either C- or Aδ-fiber nociceptors. Conclusion Thus, at one month after induction of the OA model Aβ-fiber low threshold mechanoreceptors but not C- or Aδ-fiber nociceptors had undergone changes in electrophysiological properties. If these changes reflect a change in functional role of these neurons in primary afferent sensory processing, then Aβ-fiber non-nociceptive primary sensory neurons may be involved in the pathogenesis of OA pain. Further, it is important to point out that the patterns of the changes we observed are consistent with observations in models of peripheral neuropathy but not models of peripheral inflammation.
Collapse
Affiliation(s)
- Qi Wu
- Psychiatry and Behavioral Neurosciences, McMaster University, HSC 4N35, Hamilton, Ontario, Canada
| | | |
Collapse
|
16
|
Abstract
Pain normally subserves a vital role in the survival of the organism, prompting the avoidance of situations associated with tissue damage. However, the sensation of pain can become dissociated from its normal physiological role. In conditions of neuropathic pain, spontaneous or hypersensitive pain behavior occurs in the absence of the appropriate stimuli. Our incomplete understanding of the mechanisms underlying chronic pain hypersensitivity accounts for the general ineffectiveness of currently available options for the treatment of chronic pain syndromes. Despite its complex pathophysiological nature, it is clear that neuropathic pain is associated with short- and long-term changes in the excitability of sensory neurons in the dorsal root ganglia (DRG) as well as their central connections. Recent evidence suggests that the upregulated expression of inflammatory cytokines in association with tissue damage or infection triggers the observed hyperexcitability of pain sensory neurons. The actions of inflammatory cytokines synthesized by DRG neurons and associated glial cells, as well as by astrocytes and microglia in the spinal cord, can produce changes in the excitability of nociceptive sensory neurons. These changes include rapid alterations in the properties of ion channels expressed by these neurons, as well as longer-term changes resulting from new gene transcription. In this chapter we review the diverse changes produced by inflammatory cytokines in the behavior of sensory neurons in the context of chronic pain syndromes.
Collapse
|
17
|
Giovannoni MP, Ghelardini C, Vergelli C, Dal Piaz V. α2-Agonists as analgesic agents. Med Res Rev 2009; 29:339-68. [DOI: 10.1002/med.20134] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
18
|
Yang X, Liu Z, Li Z. Effects of norepinephrine on galanin expression in dorsal root ganglion neurons in vitro. Curr Ther Res Clin Exp 2009; 70:19-28. [PMID: 24692829 DOI: 10.1016/j.curtheres.2009.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2008] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Norepinephrine (NE) is a key neurotransmitter that functionally activates adrenoreceptors expressed in sympathetic neurons. Functional α1-adrenoreceptors are also expressed in dorsal root ganglion (DRG) primary sensory neurons and regulate neurogenic inflammation and nociceptive responses. Galanin is involved in inflammation and nociception. It has been suggested that galanin receptor (GalR) 1 and GalR3 activation induces analgesia at the level of the spinal cord, while activation of GalR2 has a pronociceptive role in the periphery. Whether activation or inhibition of α-adrenoreceptors influences galanin expression remains unknown. OBJECTIVE The aim of the present study was to investigate whether the α-adrenoreceptor agonist NE, the α1-adrenoreceptor antagonist prazosin, and the α2-adrenoreceptor antagonist yohimbine affect galanin expression in primary cultured DRG neurons. METHODS DRG was dissected from 240 embryonic 15-day-old Wistar rats, cultured as dissociated cells for 2 days, and then exposed to NE (10(-4) mol/L) for another 4 days. In the NE + prazosin group and the NE + yohimbine group, DRG neurons were pretreated with prazosin (10(-6) mol/L) and yohimbine (10(-5) mol/L), respectively, 10 minutes prior to the NE challenge. The neurons cultured continuously in media served as the controls. All of the cultured samples were processed to detect galanin mRNA and galanin peptide expression by reverse transcriptase-polymerase chain reaction and Western blot, respectively. Five samples were tested for each procedure. RESULTS Forty samples were prepared for this study and included in the analysis. After 4 days of incubation, mean (SD) galanin mRNA/β-actin mRNA concentration ratio was significantly increased with NE compared with controls (0.3349 [0.0413] vs 0.2411 [0.0519]; P < 0.05). Pretreatment with prazosin seemed to block the effects of NE (0.2522 [0.0496]; P < 0.05 vs NE), while yohimbine did not appear to significantly alter the effects of NE on elevation of galanin mRNA/β-actin mRNA concentration (0.3154 [0.0239]; P < 0.05 vs controls). After 4 days of incubation, galanin/β-actin concentration ratio was significantly higher with NE compared with controls (0.4406 [0.0655] vs 0.2295 [0.0794]; P < 0.01). Pretreatment with prazosin appeared to inhibit NE-induced galanin peptide expression (0.3156 [0.0942]; P < 0.05 vs NE), while yohimbine did not appear to alter the effects of NE on elevation of galanin peptide concentration (0.3700 [0.0533]; P < 0.05 vs controls). Coclusions: In this small in vitro study, NE, likely due to action on α1-adrenoreceptors but not α2-adrenoreceptors, was associated with an increase in galanin mRNA concentration and galanin peptide expression in these DRG neurons. These findings might be relevant to noradrenergic pain modulation.
Collapse
Affiliation(s)
- Xiangdong Yang
- Department of Nephrology, Shandong University Qilu Hospital, Jinan, People's Republic of China
| | - Zhen Liu
- Department of Anatomy, Shandong University School of Medicine, Jinan, People's Republic of China
| | - Zhenzhong Li
- Department of Anatomy, Shandong University School of Medicine, Jinan, People's Republic of China
| |
Collapse
|
19
|
|
20
|
Electrophysiologic characteristics of large neurons in dorsal root ganglia during development and after hind paw incision in the rat. Anesthesiology 2008; 109:111-7. [PMID: 18580180 DOI: 10.1097/aln.0b013e31817c1ab9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Withdrawal thresholds in the paw are lower in younger animals, and incision further reduces these thresholds. The authors hypothesized that these differences result in part from changes in intrinsic electrophysiologic properties of large neurons. METHODS Using isolated whole dorsal root ganglion, current clamping was performed to determine the electrophysiologic properties of large neurons before and after incision in animals aged 1 and 4 weeks. Mechanical withdrawal thresholds were used to follow paw sensitivity. RESULTS After paw incision, withdrawal thresholds decreased to a similar degree at both ages, but returned to control threshold at 72 h only in the 1-week-old animals. The resting membrane potential was less negative and the rheobase and the resistance of the membrane were lower at baseline in the 1-week-old animals (P < 0.05). After incision, the membrane potential became more depolarized and the rheobase was less in both ages. These changes remained 72 h after the incision in both ages. CONCLUSION These findings suggest that lower mechanical thresholds in the younger animals may be partially attributed to the intrinsic electrophysiologic properties of the larger-diameter afferent neurons. The lack of resolution of the electrophysiologic changes in the young despite the resolution of the withdrawal response suggests that continued input from large fibers into the central nervous system may occur at this age despite the apparent resolution of behavioral changes. Further studies are needed to determine the etiology of these differences, their impact in the central nervous system, and whether theses changes can be prevented.
Collapse
|
21
|
Hur YK, Choi IS, Cho JH, Park EJ, Choi JK, Choi BJ, Jang IS. Effects of carbamazepine and amitriptyline on tetrodotoxinresistant Na+ channels in immature rat trigeminal ganglion neurons. Arch Pharm Res 2008; 31:178-82. [PMID: 18365687 DOI: 10.1007/s12272-001-1138-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Although anticonvulsant drugs that block voltage-dependent Na+ channels have been widely used for neuropathic pain, including peripheral nerve injury-induced pain, much less is known about the actions of these drugs on immature trigeminal ganglion (TG) neurons. Here we report the effects of carbamazepine (CBZ) and amitriptyline (ATL) on tetrodotoxin-resistant (TTX-R) Na' channels expressed on immature rat TG neurons. TTX-R Na+ currents (I(Na)) were recorded in the presence of 300 nM TTX by use of a conventional whole-cell patch clamp method. Both CBZ and ATL inhibited TTX-R I(Na) in a concentration-dependent manner, but ATL was more potent. While CBZ and ATL did not affect the overall voltage-activation relationship of TTX-R Na+ channels, both drugs shifted the voltage-activation relationship to the left, indicating that they inhibited TTX-R Na+ channels more efficiently at depolarized membrane potentials. ATL showed a profound use-dependent blockade of TTX-R I(Na), but CBZ had little effect. The present results suggest that both CBZ and ATL, common drugs used for treating neuropathic pain, efficiently inhibit TTX-R Na+ channels expressed on immature TG neurons, and that these drugs might be useful for the treatment of trigeminal nerve injury-induced neuropathic pain, as well as the inhibition of ongoing central sensitization, even during immature periods.
Collapse
Affiliation(s)
- Yun-Kyung Hur
- Department of Oral Medicine, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea
| | | | | | | | | | | | | |
Collapse
|
22
|
White FA, Jung H, Miller RJ. Chemokines and the pathophysiology of neuropathic pain. Proc Natl Acad Sci U S A 2007; 104:20151-8. [PMID: 18083844 PMCID: PMC2154400 DOI: 10.1073/pnas.0709250104] [Citation(s) in RCA: 260] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Indexed: 11/18/2022] Open
Abstract
Chemokines and chemokine receptors are widely expressed by cells of the immune and nervous systems. This review focuses on our current knowledge concerning the role of chemokines in the pathophysiology of chronic pain syndromes. Injury- or disease-induced changes in the expression of diverse chemokines and their receptors have been demonstrated in the neural and nonneural elements of pain pathways. Under these circumstances, chemokines have been shown to modulate the electrical activity of neurons by multiple regulatory pathways including increases in neurotransmitter release through Ca-dependent mechanisms and transactivation of transient receptor channels. Either of these mechanisms alone, or in combination, may contribute to sustained excitability of primary afferent and secondary neurons within spinal pain pathways. Another manner in which chemokines may influence sustained neuronal excitability may be their ability to function as excitatory neurotransmitters within the peripheral and central nervous system. As is the case for traditional neurotransmitters, injury-induced up-regulated chemokines are found within synaptic vesicles. Chemokines released after depolarization of the cell membrane can then act on other chemokine receptor-bearing neurons, glia, or immune cells. Because up-regulation of chemokines and their receptors may be one of the mechanisms that directly or indirectly contribute to the development and maintenance of chronic pain, these molecules may then represent novel targets for therapeutic intervention in chronic pain states.
Collapse
Affiliation(s)
- Fletcher A. White
- *Departments of Cell Biology, Neurobiology and Anatomy, and Anesthesiology, Loyola University Chicago, Maywood, IL 60626; and
| | - Hosung Jung
- Molecular Pharmacology and Structural Biochemistry, Northwestern University, Chicago, IL 60611
| | - Richard J. Miller
- Molecular Pharmacology and Structural Biochemistry, Northwestern University, Chicago, IL 60611
| |
Collapse
|
23
|
Carroll I, Mackey S, Gaeta R. The role of adrenergic receptors and pain: The good, the bad, and the unknown. ACTA ACUST UNITED AC 2007. [DOI: 10.1053/j.sane.2006.11.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
24
|
Pertovaara A. Noradrenergic pain modulation. Prog Neurobiol 2006; 80:53-83. [PMID: 17030082 DOI: 10.1016/j.pneurobio.2006.08.001] [Citation(s) in RCA: 395] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 08/25/2006] [Accepted: 08/30/2006] [Indexed: 11/18/2022]
Abstract
Norepinephrine is involved in intrinsic control of pain. Main sources of norepinephrine are sympathetic nerves peripherally and noradrenergic brainstem nuclei A1-A7 centrally. Peripheral norepinephrine has little influence on pain in healthy tissues, whereas in injured tissues it has variable effects, including aggravation of pain. Its peripheral pronociceptive effect has been associated with injury-induced expression of novel noradrenergic receptors, sprouting of sympathetic nerve fibers, and pronociceptive changes in the ionic channel properties of primary afferent nociceptors, while an interaction with the immune system may contribute in part to peripheral antinociception induced by norepinephrine. In the spinal cord, norepinephrine released from descending pathways suppresses pain by inhibitory action on alpha-2A-adrenoceptors on central terminals of primary afferent nociceptors (presynaptic inhibition), by direct alpha-2-adrenergic action on pain-relay neurons (postsynaptic inhibition), and by alpha-1-adrenoceptor-mediated activation of inhibitory interneurons. Additionally, alpha-2C-adrenoceptors on axon terminals of excitatory interneurons of the spinal dorsal horn possibly contribute to spinal control of pain. At supraspinal levels, the pain modulatory effect by norepinephrine and noradrenergic receptors has varied depending on many factors such as the supraspinal site, the type of the adrenoceptor, the duration of the pain and pathophysiological condition. While in baseline conditions the noradrenergic system may have little effect, sustained pain induces noradrenergic feedback inhibition of pain. Noradrenergic systems may also contribute to top-down control of pain, such as induced by a change in the behavioral state. Following injury or inflammation, the central as well as peripheral noradrenergic system is subject to various plastic changes that influence its antinociceptive efficacy.
Collapse
Affiliation(s)
- Antti Pertovaara
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, PO Box 63, University of Helsinki, FIN-00014 Helsinki, Finland.
| |
Collapse
|
25
|
Liu B, Eisenach JC. Perineural clonidine reduces p38 mitogen-activated protein kinase activation in sensory neurons. Neuroreport 2006; 17:1313-7. [PMID: 16951576 DOI: 10.1097/01.wnr.0000227995.45917.f5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Perineural injection of clonidine at the site of nerve injury reduces hypersensitivity while simultaneously reducing leukocyte number and cytokine expression and hyperexcitability in sensory neurons. The activation of p38 mitogen-activated protein kinase in sensory neurons contributes to the development and maintenance of inflammatory and neuropathic pain. Here, we tested whether perineural clonidine affected activation of p38 mitogen-activated protein kinase following partial sciatic nerve ligation. Perineural clonidine significantly increased withdrawal threshold and concomitantly reduced phosphorylation of p38 mitogen-activated protein kinase in sensory neurons ipsilateral to injury. Clonidine's effects were blocked by the alpha2-adrenoceptor antagonist, BRL44408. These data suggest that activation of alpha2-adrenoceptors at the site of nerve injury, probably by immune modulation, reduces intracellular signaling in primary afferents that leads to hypersensitivity.
Collapse
Affiliation(s)
- Baogang Liu
- Department of Anesthesiology, Center for the Study of Pharmacologic Plasticity in the Presence of Pain, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
| | | |
Collapse
|