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Kaur J, Mazzone GL, Aquino JB, Nistri A. Nicotine Neurotoxicity Involves Low Wnt1 Signaling in Spinal Locomotor Networks of the Postnatal Rodent Spinal Cord. Int J Mol Sci 2021; 22:ijms22179572. [PMID: 34502498 PMCID: PMC8431663 DOI: 10.3390/ijms22179572] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 12/29/2022] Open
Abstract
The postnatal rodent spinal cord in-vitro is a useful model to investigate early pathophysiological changes after injury. While low dose nicotine (1 µM) induces neuroprotection, how higher doses affect spinal networks is unknown. Using spinal preparations of postnatal wild-type Wistar rat and Wnt1Cre2:Rosa26Tom double-transgenic mouse, we studied the effect of nicotine (0.5–10 µM) on locomotor networks in-vitro. Nicotine 10 µM induced motoneuron depolarization, suppressed monosynaptic reflexes, and decreased fictive locomotion in rat spinal cord. Delayed fall in neuronal numbers (including motoneurons) of central and ventral regions emerged without loss of dorsal neurons. Conversely, nicotine (0.5–1 µM) preserved neurons throughout the spinal cord and strongly activated the Wnt1 signaling pathway. High-dose nicotine enhanced expression of S100 and GFAP in astrocytes indicating a stress response. Excitotoxicity induced by kainate was contrasted by nicotine (10 µM) in the dorsal area and persisted in central and ventral regions with no change in basal Wnt signaling. When combining nicotine with kainate, the activation of Wnt1 was reduced compared to kainate/sham. The present results suggest that high dose nicotine was neurotoxic to central and ventral spinal neurons as the neuroprotective role of Wnt signaling became attenuated. This also corroborates the risk of cigarette smoking for the foetus/newborn since tobacco contains nicotine.
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Affiliation(s)
- Jaspreet Kaur
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark
- Department of Neuroscience, International School for Advanced Studies (SISSA), 34136 Trieste, Italy;
- Correspondence: (J.K.); (G.L.M.); Tel.: +45-5260-1502 (J.K.); +54-23-0438-7425 (G.L.M.)
| | - Graciela L. Mazzone
- Department of Neuroscience, International School for Advanced Studies (SISSA), 34136 Trieste, Italy;
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Universidad Austral, Av. Pte. Perón 1500, Pilar B1629AHJ, Buenos Aires, Argentina;
- Correspondence: (J.K.); (G.L.M.); Tel.: +45-5260-1502 (J.K.); +54-23-0438-7425 (G.L.M.)
| | - Jorge B. Aquino
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Universidad Austral, Av. Pte. Perón 1500, Pilar B1629AHJ, Buenos Aires, Argentina;
| | - Andrea Nistri
- Department of Neuroscience, International School for Advanced Studies (SISSA), 34136 Trieste, Italy;
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The neuroprotective effects of activated α7 nicotinic acetylcholine receptor against mutant copper-zinc superoxide dismutase 1-mediated toxicity. Sci Rep 2020; 10:22157. [PMID: 33335227 PMCID: PMC7746719 DOI: 10.1038/s41598-020-79189-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 12/02/2020] [Indexed: 11/08/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective and progressive loss of motor neurons. Although many drugs have entered clinical trials, few have shown effectiveness in the treatment of ALS. Other studies have shown that the stimulation of α7 nicotinic acetylcholine receptor (nAChR) can have neuroprotective effects in some models of neurodegenerative disease, as well as prevent glutamate-induced motor neuronal death. However, the effect of α7 nAChR agonists on ALS-associated mutant copper-zinc superoxide dismutase 1 (SOD1) aggregates in motor neurons remains unclear. In the present study, we examined whether α7 nAChR activation had a neuroprotective effect against SOD1G85R-induced toxicity in a cellular model for ALS. We found that α7 nAChR activation by PNU282987, a selective agonist of α7 nAChR, exhibited significant neuroprotective effects against SOD1G85R-induced toxicity via the reduction of intracellular protein aggregates. This reduction also correlated with the activation of autophagy through the AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, the activation of α7 nAChRs was found to increase the biogenesis of lysosomes by inducing translocation of the transcription factor EB (TFEB) into the nucleus. These results support the therapeutic potential of α7 nAChR activation in diseases that are characterized by SOD1G85R aggregates, such as ALS.
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Balanced cholinergic modulation of spinal locomotor circuits via M2 and M3 muscarinic receptors. Sci Rep 2019; 9:14051. [PMID: 31575899 PMCID: PMC6773880 DOI: 10.1038/s41598-019-50452-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/12/2019] [Indexed: 01/05/2023] Open
Abstract
Neuromodulation ensures that neural circuits produce output that is flexible whilst remaining within an optimal operational range. The neuromodulator acetylcholine is released during locomotion to regulate spinal motor circuits. However, the range of receptors and downstream mechanisms by which acetylcholine acts have yet to be fully elucidated. We therefore investigated metabotropic acetylcholine receptor-mediated modulation by using isolated spinal cord preparations from neonatal mice in which locomotor-related output can be induced pharmacologically. We report that M2 receptor blockade decreases the frequency and amplitude of locomotor-related activity, whilst reducing its variability. In contrast, M3 receptor blockade destabilizes locomotor-related bursting. Motoneuron recordings from spinal cord slices revealed that activation of M2 receptors induces an outward current, decreases rheobase, reduces the medium afterhyperpolarization, shortens spike duration and decreases synaptic inputs. In contrast, M3 receptor activation elicits an inward current, increases rheobase, extends action potential duration and increases synaptic inputs. Analysis of miniature postsynaptic currents support that M2 and M3 receptors modulate synaptic transmission via different mechanisms. In summary, we demonstrate that M2 and M3 receptors have opposing modulatory actions on locomotor circuit output, likely reflecting contrasting cellular mechanisms of action. Thus, intraspinal cholinergic systems mediate balanced, multimodal control of spinal motor output.
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Kaur J, Rauti R, Nistri A. Nicotine‐mediated neuroprotection of rat spinal networks against excitotoxicity. Eur J Neurosci 2018; 47:1353-1374. [DOI: 10.1111/ejn.13950] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 03/19/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Jaspreet Kaur
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
- Jaspreet Kaur, Institute of Neurosciences of Timone (IMAPATH Team) ‐ CERIMEDUMR 7289Aix‐Marseille University 27, boulevard Jean Moulin Marseille Cedex 05 13385 France
| | - Rossana Rauti
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
| | - Andrea Nistri
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
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5
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Bagdas D, Gurun MS, Flood P, Papke RL, Damaj MI. New Insights on Neuronal Nicotinic Acetylcholine Receptors as Targets for Pain and Inflammation: A Focus on α7 nAChRs. Curr Neuropharmacol 2018; 16:415-425. [PMID: 28820052 PMCID: PMC6018191 DOI: 10.2174/1570159x15666170818102108] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/20/2017] [Accepted: 08/16/2017] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Nicotine and nicotinic acetylcholine receptors (nAChRs) have been explored for the past three decades as targets for pain control. The aim of this review is to introduce readers particularly to α7 nAChRs in a perspective of pain and its modulation. METHODS Developments for α7 nAChR modulators and recent animal studies related to pain are reviewed. RESULTS Accumulating evidences suggest that selective ligands for α7 nAChRs hold promise in the treatment of chronic pain conditions as they lack many of side effects associated with other nicotinic receptor types. CONCLUSION This review provides the reader recent insights on α7 nAChRs from structure and function to the latest findings on the pharmacology and therapeutic targeting of these receptors for the treatment of pain and inflammation.
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Affiliation(s)
- Deniz Bagdas
- Address correspondence to this author at the Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613; Tel/Fax: +1-804-828-9256; E-mail:
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Hone AJ, McIntosh JM. Nicotinic acetylcholine receptors in neuropathic and inflammatory pain. FEBS Lett 2017; 592:1045-1062. [PMID: 29030971 DOI: 10.1002/1873-3468.12884] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/22/2017] [Accepted: 10/05/2017] [Indexed: 01/11/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are actively being investigated as therapeutic targets for the treatment of pain and inflammation, but despite more than 30 years of research, there are currently no FDA-approved analgesics that are specific for these receptors. Much of the initial research effort focused on the α4β2 nAChR subtype, but more recently, additional subtypes have been identified as promising new leads and include α6β4, α7, and α9-containing nAChRs. This Review will focus on the distribution of these nAChRs in the cell types involved in neuropathic pain and inflammation and the activity of currently available nicotinic ligands.
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Affiliation(s)
- Arik J Hone
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, USA.,Department of Psychiatry, University of Utah, Salt Lake City, UT, USA.,George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, USA
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Sokolov AY, Murzina AA, Osipchuk AV, Lyubashina OA, Amelin AV. Cholinergic mechanisms of headaches. NEUROCHEM J+ 2017. [DOI: 10.1134/s1819712417020131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Bagdas D, Wilkerson JL, Kulkarni A, Toma W, AlSharari S, Gul Z, Lichtman AH, Papke RL, Thakur GA, Damaj MI. The α7 nicotinic receptor dual allosteric agonist and positive allosteric modulator GAT107 reverses nociception in mouse models of inflammatory and neuropathic pain. Br J Pharmacol 2016; 173:2506-20. [PMID: 27243753 DOI: 10.1111/bph.13528] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 05/05/2016] [Accepted: 05/17/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Orthosteric agonists and positive allosteric modulators (PAMs) of the α7 nicotinic ACh receptor (nAChR) represent novel therapeutic approaches for pain modulation. Moreover, compounds with dual function as allosteric agonists and PAMs, known as ago-PAMs, add further regulation of receptor function. EXPERIMENTAL APPROACH Initial studies examined the α7 ago-PAM, GAT107, in the formalin, complete Freund's adjuvant (CFA), LPS inflammatory pain models, the chronic constriction injury neuropathic pain model and the tail flick and hot plate acute thermal nociceptive assays. Additional studies examined the locus of action of GAT107 and immunohistochemical markers in the dorsal horn of the spinal cord in the CFA model. KEY RESULTS Complementary pharmacological and genetic approaches confirmed that the dose-dependent antinociceptive effects of GAT107 were mediated through α7 nAChR. However, GAT107 was inactive in the tail flick and hot plate assays. In addition, GAT107 blocked conditioned place aversion elicited by acetic acid injection. Furthermore, intrathecal, but not intraplantar, injections of GAT107 reversed nociception in the CFA model, suggesting a spinal component of action. Immunohistochemical evaluation revealed an increase in the expression of astrocyte-specific glial fibrillary acidic protein and phosphorylated p38MAPK within the spinal cords of mice treated with CFA, which was attenuated by intrathecal GAT107 treatment. Importantly, GAT107 did not elicit motor impairment and continued to produce antinociceptive effects after subchronic administration in both phases of the formalin test. CONCLUSIONS AND IMPLICATIONS Collectively, these results provide the first proof of principle that α7 ago-PAMs represent an effective pharmacological strategy for treating inflammatory and neuropathic pain.
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Affiliation(s)
- Deniz Bagdas
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.,Experimental Animals Breeding and Research Center, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Jenny L Wilkerson
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Abhijit Kulkarni
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Wisam Toma
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Shakir AlSharari
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.,Department of Pharmacology and Toxicology, King Saud University, Riyadh, Saudi Arabia
| | - Zulfiye Gul
- Department of Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
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Lee JH, Go D, Kim W, Lee G, Bae H, Quan FS, Kim SK. Involvement of spinal muscarinic and serotonergic receptors in the anti-allodynic effect of electroacupuncture in rats with oxaliplatin-induced neuropathic pain. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:407-14. [PMID: 27382357 PMCID: PMC4930909 DOI: 10.4196/kjpp.2016.20.4.407] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/15/2016] [Accepted: 06/01/2016] [Indexed: 01/28/2023]
Abstract
This study was performed to investigate whether the spinal cholinergic and serotonergic analgesic systems mediate the relieving effect of electroacupuncture (EA) on oxaliplatin-induced neuropathic cold allodynia in rats. The cold allodynia induced by an oxaliplatin injection (6 mg/kg, i.p.) was evaluated by immersing the rat's tail into cold water (4℃) and measuring the withdrawal latency. EA stimulation (2 Hz, 0.3-ms pulse duration, 0.2~0.3 mA) at the acupoint ST36, GV3, or LI11 all showed a significant anti-allodynic effect, which was stronger at ST36. The analgesic effect of EA at ST36 was blocked by intraperitoneal injection of muscarinic acetylcholine receptor antagonist (atropine, 1 mg/kg), but not by nicotinic (mecamylamine, 2 mg/kg) receptor antagonist. Furthermore, intrathecal administration of M2 (methoctramine, 10 µg) and M3 (4-DAMP, 10 µg) receptor antagonist, but not M1 (pirenzepine, 10 µg) receptor antagonist, blocked the effect. Also, spinal administration of 5-HT3 (MDL-72222, 12 µg) receptor antagonist, but not 5-HT1A (NAN-190, 15 µg) or 5-HT2A (ketanserin, 30 µg) receptor antagonist, prevented the anti-allodynic effect of EA. These results suggest that EA may have a signifi cant analgesic action against oxaliplatin-induced neuropathic pain, which is mediated by spinal cholinergic (M2, M3) and serotonergic (5-HT3) receptors.
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Affiliation(s)
- Ji Hwan Lee
- Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea
| | - Donghyun Go
- Department of East-West Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea
| | - Woojin Kim
- Department of East-West Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea.; Department of Physiology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea
| | - Giseog Lee
- Department of East-West Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea.; Department of Physiology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea
| | - Hyojeong Bae
- Department of East-West Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea
| | - Fu Shi Quan
- Department of Medical Zoology, School of Medicine, Kyung Hee University, Seoul 02447, Korea
| | - Sun Kwang Kim
- Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea.; Department of East-West Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea.; Department of Physiology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea
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10
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Mine N, Taniguchi W, Nishio N, Izumi N, Miyazaki N, Yamada H, Nakatsuka T, Yoshida M. Synaptic modulation of excitatory synaptic transmission by nicotinic acetylcholine receptors in spinal ventral horn neurons. Neuroscience 2015; 290:18-30. [PMID: 25613686 DOI: 10.1016/j.neuroscience.2015.01.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 12/18/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are distributed widely in the central nervous system and play important roles in higher brain functions, including learning, memory, and recognition. However, functions of the cholinergic system in spinal motoneurons remain poorly understood. In this study, we investigated the actions of presynaptic and postsynaptic nAChRs in spinal ventral horn neurons by performing whole-cell patch-clamp recordings on lumbar slices from male rats. The application of nicotine or acetylcholine generated slow inward currents and increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs). Slow inward currents by acetylcholine or nicotine were not inhibited by tetrodotoxin (TTX) or glutamate receptor antagonists. In the presence of TTX, the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs) were also increased by acetylcholine or nicotine. A selective α4β2 nicotinic receptor antagonist, dihydro-β-erythroidine hydrobromide (DhβE), significantly decreased nicotine-induced inward currents without affecting the enhancement of sEPSCs and mEPSCs. In addition, a selective α7 nicotinic receptor antagonist, methyllycaconitine, did not affect either nicotine-induced inward currents or the enhancement of sEPSCs and mEPSCs. These results suggest that α4β2 AChRs are localized at postsynaptic sites in the spinal ventral horn, non-α4β2 and non-α7 nAChRs are located presynaptically, and nAChRs enhance excitatory synaptic transmission in the spinal ventral horn.
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Affiliation(s)
- N Mine
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - W Taniguchi
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan.
| | - N Nishio
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan
| | - N Izumi
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - N Miyazaki
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - H Yamada
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - T Nakatsuka
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan
| | - M Yoshida
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
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11
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Yoon H, Kim MJ, Yoon I, Li DX, Bae H, Kim SK. Nicotinic Acetylcholine Receptors Mediate the Suppressive Effect of an Injection of Diluted Bee Venom into the GV3 Acupoint on Oxaliplatin-Induced Neuropathic Cold Allodynia in Rats. Biol Pharm Bull 2015; 38:710-4. [DOI: 10.1248/bpb.b14-00797] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Heera Yoon
- Department of Physiology, College of Korean Medicine, Kyung Hee University
| | - Min Joon Kim
- Department of East-West Medicine, Graduate School, Kyung Hee University
| | - Insoo Yoon
- Department of Physiology, College of Korean Medicine, Kyung Hee University
| | - Dong Xing Li
- Department of Physiology, College of Korean Medicine, Kyung Hee University
| | - Hyunsu Bae
- Department of Physiology, College of Korean Medicine, Kyung Hee University
| | - Sun Kwang Kim
- Department of East-West Medicine, Graduate School, Kyung Hee University
- Department of Physiology, College of Korean Medicine, Kyung Hee University
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Roberson DP, Binshtok AM, Blasl F, Bean BP, Woolf CJ. Targeting of sodium channel blockers into nociceptors to produce long-duration analgesia: a systematic study and review. Br J Pharmacol 2012; 164:48-58. [PMID: 21457220 DOI: 10.1111/j.1476-5381.2011.01391.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE We have developed a strategy to target the permanently charged lidocaine derivative lidocaine N-ethyl bromide (QX-314) selectively into nociceptive sensory neurons through the large-pore transient receptor potential cation channel subfamily V (TRPV1) noxious heat detector channel. This involves co-administration of QX-314 and a TRPV1 agonist to produce a long-lasting local analgesia. For potential clinical use we propose using lidocaine as the TRPV1 agonist, because it activates TRPV1 at clinical doses. EXPERIMENTAL APPROACH We conducted experiments in rats to determine optimal concentrations and ratios of lidocaine and QX-314 that produce the greatest degree and duration of pain-selective block when administered nearby the sciatic nerve: reduction in the response to noxious mechanical (pinch) and to radiant heat stimuli, with minimal disruption in motor function (grip strength). KEY RESULTS A combination of 0.5% QX-314 and 2% lidocaine produced 1 h of non-selective sensory and motor block followed by >9 h of pain-selective block, where grip strength was unimpaired. QX-314 at this concentration had no effect by itself, while 2% lidocaine by itself produced 1 h of non-selective block. The combination of 0.5% QX-314 and 2% lidocaine was the best of the many tested, in terms of the duration and selectivity of local analgesia. CONCLUSIONS AND IMPLICATIONS Targeting charged sodium channel blockers into specific sets of axons via activation of differentially expressed large-pore channels provides an opportunity to produce prolonged local analgesia, and represents an example of how exploiting ion channels as a drug delivery port can be used to increase the specificity and efficacy of therapeutics.
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Affiliation(s)
- D P Roberson
- FM Kirby Neurobiology Center and Department of Neurology, Children's Hospital, Boston, MA 02115, USA
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13
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Hone AJ, Meyer EL, McIntyre M, McIntosh JM. Nicotinic acetylcholine receptors in dorsal root ganglion neurons include the α6β4* subtype. FASEB J 2011; 26:917-26. [PMID: 22024738 DOI: 10.1096/fj.11-195883] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The α6-containing nicotinic acetylcholine receptors (nAChRs) have recently been implicated in diseases of the central nervous system (CNS), including Parkinson's disease and substance abuse. In contrast, little is known about the role of α6* nAChRs in the peripheral nervous system (where the asterisk denotes the possible presence of additional subunits). Dorsal root ganglia (DRG) neurons are known to express nAChRs with a pharmacology consistent with an α7, α3β4*, and α4β2* composition. Here we present evidence that DRG neurons also express α6* nAChRs. We used RT-PCR to show the presence of α6 subunit transcripts and patch-clamp electrophysiology together with subtype-selective α-conotoxins to pharmacologically characterize the nAChRs in rat DRG neurons. α-Conotoxin BuIA (500 nM) blocked acetylcholine-gated currents (I(ACh)) by 90.3 ± 3.0%; the recovery from blockade was very slow, indicating a predominance of α(x)β4* nAChRs. Perfusion with either 300 nM BuIA[T5A;P6O] or 200 nM MII[E11A], α-conotoxins that target the α6β4* subtype, blocked I(ACh) by 49.3 ± 5 and 46.7 ± 8%, respectively. In these neurons, I(ACh) was relatively insensitive to 200 nM ArIB[V11L;V16D] (9.4±2.0% blockade) or 500 nM PnIA (23.0±4% blockade), α-conotoxins that target α7 and α3β2*/α6β2* nAChRs, respectively. We conclude that α6β4* nAChRs are among the subtypes expressed by DRG, and to our knowledge, this is the first demonstration of α6β4* in neurons outside the CNS.
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Affiliation(s)
- Arik J Hone
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, USA
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14
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Huang H, Xu Y, van den Pol AN. Nicotine excites hypothalamic arcuate anorexigenic proopiomelanocortin neurons and orexigenic neuropeptide Y neurons: similarities and differences. J Neurophysiol 2011; 106:1191-202. [PMID: 21653710 DOI: 10.1152/jn.00740.2010] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Two of the biggest health problems facing us today are addiction to nicotine and the increased prevalence of obesity. Interestingly, nicotine attenuates obesity, but the underlying mechanism is not clear. Here we address the hypothesis that if weight-reducing actions of nicotine are mediated by anorexigenic proopiomelanocortin (POMC) neurons of the hypothalamic arcuate nucleus, nicotine should excite these cells. Nicotine at concentrations similar to those found in smokers, 100-1,000 nM, excited POMC cells by mechanisms based on increased spike frequency, depolarization of membrane potential, and opening of ion channels. This was mediated by activation of both α7 and α4β2 nicotinic receptors; by itself, this nicotine-mediated excitation could explain weight loss caused by nicotine. However, in control experiments nicotine also excited the orexigenic arcuate nucleus neuropeptide Y (NPY) cells. Nicotine exerted similar actions on POMC and NPY cells, with a slightly greater depolarizing action on POMC cells. Immunocytochemistry revealed cholinergic axons terminating on both cell types. Nicotine actions were direct in both cell types, with nicotine depolarizing the membrane potentials and reducing input resistance. We found no differences in the relative desensitization to nicotine between POMC and NPY neurons. Nicotine inhibited excitatory synaptic activity recorded in NPY, but not POMC, cells. Nicotine also excited hypocretin/orexin neurons that enhance cognitive arousal, but the responses were smaller than in NPY or POMC cells. Together, these results indicate that nicotine has a number of similar actions, but also a few different actions, on POMC and NPY neurons that could contribute to the weight loss associated with smoking.
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Affiliation(s)
- Hao Huang
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar St. New Haven, CT 06520, USA
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Gao B, Hierl M, Clarkin K, Juan T, Nguyen H, van der Valk M, Deng H, Guo W, Lehto SG, Matson D, McDermott JS, Knop J, Gaida K, Cao L, Waldon D, Albrecht BK, Boezio AA, Copeland KW, Harmange JC, Springer SK, Malmberg AB, McDonough SI. Pharmacological effects of nonselective and subtype-selective nicotinic acetylcholine receptor agonists in animal models of persistent pain. Pain 2010; 149:33-49. [DOI: 10.1016/j.pain.2010.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 12/16/2009] [Accepted: 01/11/2010] [Indexed: 12/20/2022]
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Gear RW, Levine JD. Rostral ventral medulla cholinergic mechanism in pain-induced analgesia. Neurosci Lett 2009; 464:170-2. [PMID: 19699268 DOI: 10.1016/j.neulet.2009.08.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 10/20/2022]
Abstract
The ascending nociceptive control (ANC), a novel spinostriatal pain modulation pathway, mediates a form of pain-induced analgesia referred to as noxious stimulus-induced antinociception (NSIA). ANC includes specific spinal cord mechanisms as well as circuitry in nucleus accumbens, a major component of the ventral striatum. Here, using the trigeminal jaw-opening reflex (JOR) in the rat as a nociceptive assay, we show that microinjection of the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine into the rostral ventral medulla (RVM) blocks NSIA, implicating RVM as a potentially important link between ANC and the PAG-RVM-spinal descending pain modulation system. A circuit connecting nucleus accumbens to the RVM is proposed as a novel striato-RVM pathway.
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Affiliation(s)
- Robert W Gear
- Department of Oral and Maxillofacial Surgery, University of California, San Francisco, California 94143-0440, United States.
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Matsumoto M, Xie W, Inoue M, Ueda H. Evidence for the tonic inhibition of spinal pain by nicotinic cholinergic transmission through primary afferents. Mol Pain 2007; 3:41. [PMID: 18088441 PMCID: PMC2234393 DOI: 10.1186/1744-8069-3-41] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 12/19/2007] [Indexed: 11/17/2022] Open
Abstract
Background We have proposed that nerve injury-specific loss of spinal tonic cholinergic inhibition may play a role in the analgesic effects of nicotinic acetylcholine receptor (nAChR) agonists on neuropathic pain. However, the tonic cholinergic inhibition of pain remains to be well characterized. Results Here, we show that choline acetyltransferase (ChAT) signals were localized not only in outer dorsal horn fibers (lamina I–III) and motor neurons in the spinal cord, but also in the vast majority of neurons in the dorsal root ganglion (DRG). When mice were treated with an antisense oligodeoxynucleotide (AS-ODN) against ChAT, which decreased ChAT signals in the dorsal horn and DRG, but not in motor neurons, they showed a significant decrease in nociceptive thresholds in paw pressure and thermal paw withdrawal tests. Furthermore, in a novel electrical stimulation-induced paw withdrawal (EPW) test, the thresholds for stimulation through C-, Aδ- and Aβ-fibers were all decreased by AS-ODN-pretreatments. The administration of nicotine (10 nmol i.t.) induced a recovery of the nociceptive thresholds, decreased by the AS-ODN, in the mechanical, thermal and EPW tests. However, nicotine had no effects in control mice or treated with a mismatch scramble (MS)-ODN in all of these nociception tests. Conclusion These findings suggest that primary afferent cholinergic neurons produce tonic inhibition of spinal pain through nAChR activation, and that intrathecal administration of nicotine rescues the loss of tonic cholinergic inhibition.
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Affiliation(s)
- Misaki Matsumoto
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
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