ATP mediates neuropathic pain in neuromyelitis optica via microglial activation

Abstract Background Intractable neuropathic pain is a common symptom of neuromyelitis optica spectrum disorder (NMOSD). However, the underlying mechanism of NMOSD pain remains to be elucidated. The aim of this study was to establish a novel animal model of NMOSD pain and to investigate its pathogenic mechanism. Methods We established an NMOSD pain model by injecting anti-AQP4 recombinant autoantibodies (AQP4-Ab) from NMOSD patient plasmablasts into rat spinal cords. We performed transcriptome analysis and pharmacological inhibition to elucidate the core mechanism of allodynia in the model. Results Development of mechanical allodynia was confirmed in the NMOSD pain model. AQP4-Ab mediated extracellular ATP release in vitro, and pharmacological inhibition of ATP receptor reversed mechanical allodynia in the NMOSD pain model. Furthermore, transcriptome analysis revealed microglial activation and elevated levels of IL-1β in NMOSD spinal cord. Inhibition of microglial activation and neutralization of IL-1β also attenuated neuropathic pain in the NMOSD rat model. In human patients, CSF ATP concentration was significantly higher in the acute and remission phase of NMOSD than in multiple sclerosis or other neurological disorders. Conclusion A novel NMOSD pain model was established. ATP, microglial activation, and IL-1β secretion orchestrate the pathogenesis of NMOSD neuropathic pain.

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Anti-AQP4 autoantibodies promote ATP release from astrocytes and induce mechanical pain in rats

Journal of Neuroinflammation ◽

10.1186/s12974-021-02232-w ◽

2021 ◽

Vol 18 (1) ◽

Cited By ~ 1

Author(s):

Teruyuki Ishikura ◽

Makoto Kinoshita ◽

Mikito Shimizu ◽

Yoshiaki Yasumizu ◽

Daisuke Motooka ◽

...

Keyword(s):

Neuropathic Pain ◽

Transcriptome Analysis ◽

Mechanical Allodynia ◽

Atp Release ◽

Extracellular Atp ◽

Hek293 Cells ◽

Common Symptom ◽

Pharmacological Inhibition ◽

Atp Concentration ◽

Aqp4 Antibody

Abstract Background Intractable neuropathic pain is a common symptom of neuromyelitis optica spectrum disorder (NMOSD). However, the underlying mechanism of NMOSD pain remains to be elucidated. In this study, we focused on ATP, which is one of the damage-associated molecular patterns, and also a well-recognized molecule involved in peripheral neuropathic pain. Methods We assessed the development of pain symptoms by injecting anti-AQP4 recombinant autoantibodies (rAQP4 IgG) into rat spinal cords. We incubated HEK293 cells expressing AQP4 (HEK-AQP4) and rat astrocytes with rAQP4 IgG and assessed the level of ATP in the supernatant. We performed transcriptome analysis of the spinal cords injected with rAQP4 IgG. Pharmacological inhibition was also applied to investigate the involvement of ATP in the development of neuropathic pain in our rat model. The ATP concentration within the cerebrospinal fluid was examined in patients with NMOSD and other neurological diseases. Results Development of mechanical allodynia was confirmed in rAQP4 IgG–treated rats. AQP4-Ab–mediated extracellular ATP release from astrocytes was observed in vitro, and pharmacological inhibition of ATP receptor reversed mechanical allodynia in the rAQP4 IgG–treated rats. Furthermore, transcriptome analysis revealed elevation of gene expressions related to several ATP receptors including P2rx4 and IL1B in the spinal cord of rAQP4 IgG–treated rats. In patients, CSF ATP concentration was significantly higher in the acute and remission phase of NMOSD than in multiple sclerosis or other neurological disorders. Conclusion Anti-AQP4 antibody was shown to induce the release of extracellular ATP from astrocytes. The ATP-mediated development of mechanical allodynia was also suggested in rats treated with anti-AQP4 antibody. Our study indicates the pivotal role of ATP in the pain mechanism of NMOSD.

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In Vitro and In Vivo Effects of Flavonoids on Peripheral Neuropathic Pain

Molecules ◽

10.3390/molecules25051171 ◽

2020 ◽

Vol 25 (5) ◽

pp. 1171 ◽

Cited By ~ 7

Author(s):

Paramita Basu ◽

Arpita Basu

Keyword(s):

Neuropathic Pain ◽

Side Effects ◽

Nerve Injury ◽

Somatosensory System ◽

Present Review ◽

Common Symptom ◽

Murine Models ◽

Peripheral Neuropathic Pain

Neuropathic pain is a common symptom and is associated with an impaired quality of life. It is caused by the lesion or disease of the somatosensory system. Neuropathic pain syndromes can be subdivided into two categories: central and peripheral neuropathic pain. The present review highlights the peripheral neuropathic models, including spared nerve injury, spinal nerve ligation, partial sciatic nerve injury, diabetes-induced neuropathy, chemotherapy-induced neuropathy, chronic constriction injury, and related conditions. The drugs which are currently used to attenuate peripheral neuropathy, such as antidepressants, anticonvulsants, baclofen, and clonidine, are associated with adverse side effects. These negative side effects necessitate the investigation of alternative therapeutics for treating neuropathic pain conditions. Flavonoids have been reported to alleviate neuropathic pain in murine models. The present review elucidates that several flavonoids attenuate different peripheral neuropathic pain conditions at behavioral, electrophysiological, biochemical and molecular biological levels in different murine models. Therefore, the flavonoids hold future promise and can be effectively used in treating or mitigating peripheral neuropathic conditions. Thus, future studies should focus on the structure-activity relationships among different categories of flavonoids and develop therapeutic products that enhance their antineuropathic effects.

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Rufinamide alleviates mechanical allodynia in a mouse neuropathic pain model

European Journal of Anaesthesiology ◽

10.1097/00003643-201106001-00622 ◽

2011 ◽

Vol 28 ◽

pp. 193

Author(s):

M. R. Suter ◽

G. Kirschmann ◽

H. Abriel ◽

I. Decosterd

Keyword(s):

Neuropathic Pain ◽

Mechanical Allodynia ◽

Pain Model ◽

Neuropathic Pain Model

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Minocycline attenuates mechanical allodynia and expression of spinal NMDA receptor 1 subunit in rat neuropathic pain model

Journal of Physiology and Biochemistry ◽

10.1007/s13105-012-0217-4 ◽

2012 ◽

Vol 69 (3) ◽

pp. 349-357 ◽

Cited By ~ 15

Author(s):

Shaofeng Pu ◽

Yongming Xu ◽

Dongping Du ◽

Meirong Yang ◽

Xin Zhang ◽

...

Keyword(s):

Neuropathic Pain ◽

Nmda Receptor ◽

Mechanical Allodynia ◽

Pain Model ◽

Neuropathic Pain Model

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A streptozotocin-induced diabetic neuropathic pain model for static or dynamic mechanical allodynia and vulvodynia: validation using topical and systemic gabapentin

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/s00210-015-1145-y ◽

2015 ◽

Vol 388 (11) ◽

pp. 1129-1140 ◽

Cited By ~ 22

Author(s):

Gowhar Ali ◽

Fazal Subhan ◽

Muzaffar Abbas ◽

Jehan Zeb ◽

Muhammad Shahid ◽

...

Keyword(s):

Neuropathic Pain ◽

Mechanical Allodynia ◽

Diabetic Neuropathic Pain ◽

Pain Model ◽

Dynamic Mechanical ◽

Neuropathic Pain Model

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Paeoniflorin Attenuates Inflammatory Pain by Inhibiting Microglial Activation and Akt-NF-κB Signaling in the Central Nervous System

Cellular Physiology and Biochemistry ◽

10.1159/000490076 ◽

2018 ◽

Vol 47 (2) ◽

pp. 842-850 ◽

Cited By ~ 14

Author(s):

Bo Hu ◽

Guangtao Xu ◽

Xiaomin Zhang ◽

Long Xu ◽

Hong Zhou ◽

...

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Signaling Pathway ◽

Inflammatory Pain ◽

Microglial Activation ◽

Enzyme Linked Immunosorbent Assay ◽

Pain Model ◽

The Central Nervous System

Background/Aims: Paeoniflorin (PF) is known to have anti-inflammatory and paregoric effects, but the mechanism underlying its analgesic effect remains unclear. The aim of this study was to clarify the effect of PF on Freund’s complete adjuvant (CFA)-induced inflammatory pain and explore the underlying molecular mechanism. Methods: An inflammatory pain model was established by intraplantar injection of CFA in C57BL/6J mice. After intrathecal injection of PF daily for 8 consecutive days, thermal and mechanical withdrawal thresholds, the levels of inflammatory factors TNF-α, IL-1β and IL-6, microglial activity, and the expression of Akt-NF-κB signaling pathway in the spinal cord tissue were detected by animal ethological test, cell culture, enzyme-linked immunosorbent assay, immunofluorescence histochemistry, and western blot. Results: PF inhibited the spinal microglial activation in the CFA-induced pain model. The production of proinflammatory cytokines was decreased in the central nervous system after PF treatment both in vivo and in vitro. PF further displayed a remarkable effect on inhibiting the activation of Akt-NF-κB signaling pathway in vivo and in vitro. Conclusion: These results suggest that PF is a potential therapeutic agent for inflammatory pain and merits further investigation.

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Rapid Morphologic and Molecular Activation of Microglial Cells by Stimulation of the P2X7 Receptor Correlates with Neuron Loss

10.21203/rs.3.rs-424697/v1 ◽

2021 ◽

Author(s):

Keith E Campagno ◽

Wennan Lu ◽

Assraa Hassan Jassim ◽

Farraj Albalawi ◽

Aurora Cenaj ◽

...

Keyword(s):

Cell Body ◽

Microglial Activation ◽

Morphological Changes ◽

Mechanical Strain ◽

Atp Release ◽

Microglial Cells ◽

Microglial Migration ◽

Process Retraction

Abstract Background: The endogenous signals leading to microglial activation represent central components of neuroinflammatory cascades. Given ATP release accompanies mechanical strain to neural tissue, and the P2X7R for ATP is expressed on microglial cells, we examined the morphological and molecular consequences of P2X7R stimulation in vivo and in vitro in detail to enhance understanding of the response. Methods: IL-1β release was determined with ELISA. Expression of mRNA used qPCR. ATP release was determined with the luciferin/luciferase assay while fura-2 indicated cytoplasmic calcium. Microglial migration used Boyden chambers. Morphological changes were quantified from Iba1-immunostained cells. Results: Sholl analysis of Iba1-stained cells showed retraction of microglial ramifications one day after injection of P2X7R agonist BzATP into mouse retinae. Mean branch length also decreased, while cell body size and expression of Nos2, Tnfa, Arg1, Chil3 increased. BzATP induced similar morphological changes in ex vivo tissue isolated from Cx3CR1-GFP mice, suggesting cell recruitment was unnecessary. Primary microglial cultures were developed to investigate the autonomous nature of the response. Isolated microglial cells expressed P2X7R, while increased intracellular Ca 2+ triggered by BzATP and blocked by antagonist A839977 confirmed functional expression. BzATP induced process retraction and cell body enlargement within minutes in isolated microglial cells, and increased expression of Nos2 and Arg1 . BzATP both increased expression of IL-1β, and triggered a substantial release, suggesting P2X7R both primes and activates the NLRP3 inflammasome. ATP increased microglial migration, but this required P2Y12R, not P2X7R involvement. As ATP release often accompanies mechanical strain, responses to intraocular pressure elevation were determined. Transient elevation increased ATP release and led to microglial process retraction, cell body enlargement and gene upregulation resembling the responses to BzATP injection. These pressure-dependent changes to microglia were reduced in P2X7R -/- mice. Critically, the loss of retinal ganglion cell neurons accompanying increased pressure was correlated with microglial activation in C57Bl/6J, but not P2X7R -/- mice.Conclusions: P2X7R stimulation induced morphological and molecular markers of activation in retinal microglial cells in vivo and in vitro , affecting IL-1β release and rapid process retraction but not cell migration. Parallel responses accompanied transient pressure elevation, suggesting ATP release and P2X7R stimulation contribute to the microglial response to rising pressure.

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Receptor Subtype Mediating the Adrenergic Sensitivity of Pain Behavior and Ectopic Discharges in Neuropathic Lewis Rats

Journal of Neurophysiology ◽

10.1152/jn.1999.81.5.2226 ◽

1999 ◽

Vol 81 (5) ◽

pp. 2226-2233 ◽

Cited By ~ 67

Author(s):

Doo Hyun Lee ◽

Xianzeng Liu ◽

Hyun Taek Kim ◽

Kyungsoon Chung ◽

Jin Mo Chung

Keyword(s):

Neuropathic Pain ◽

Dorsal Root ◽

Mechanical Allodynia ◽

Pain Behavior ◽

Receptor Subtype ◽

Systemic Injection ◽

Lewis Rats ◽

Ectopic Discharges

Receptor subtype mediating the adrenergic sensitivity of pain behavior and ectopic discharges in neuropathic Lewis rats. We attempted to identify the subtype of α-adrenergic receptor (α-AR) that is responsible for the sympathetic (adrenergic) dependency of neuropathic pain in the segmental spinal injury (SSI) model in the Lewis strain of rat. This model was chosen because our previous study showed that pain behaviors in this condition are particularly sensitive to systemic injection of phentolamine (PTL), a general α-AR blocker. We examined the effects of specific α1- and α2-AR blockers on 1) behavioral signs of mechanical allodynia, 2) ectopic discharges recorded in the in vivo condition, and 3) ectopic discharges recorded in an in vitro setup. One week after tight ligation of the L5 and L6 spinal nerves, mechanical thresholds of the paw for foot withdrawals were drastically lowered; we interpreted this change as a sign of mechanical allodynia. Signs of mechanical allodynia were significantly relieved by a systemic injection of PTL (a mixed α1- and α2-AR antagonist) or terazosin (TRZ, an α1-AR antagonist) but not by various α2-AR antagonists (idazoxan, rauwolscine, or yohimbine), suggesting that the α1-AR is in part the mediator of the signs of mechanical allodynia. Ongoing ectopic discharges were recorded from injured afferents in fascicles of the L5 dorsal root of the neuropathic rat with an in vivo recording setup. Ongoing discharge rate was significantly reduced after intraperitoneal injection of PTL or TRZ but not by idazoxan. In addition, by using an in vitro recording setup, spontaneous activity was recorded from teased dorsal root fibers in a segment in which the spinal nerve was previously ligated. Application of epinephrine to the perfusion bath enhanced ongoing discharges. This evoked activity was blocked by pretreatment with TRZ but not with idazoxan. This study demonstrated that both behavioral signs of mechanical allodynia and ectopic discharges of injured afferents in the Lewis neuropathic rat are in part mediated by mechanisms involving α1-ARs. These results suggest that the sympathetic dependency of neuropathic pain in the Lewis strain of the rat is mediated by the α1 subtype of AR.

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