scholarly journals P2Y12 receptor mediates microglial activation via RhoA/ROCK pathway in the trigeminal nucleus caudalis in a mouse model of chronic migraine

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Feng Jing ◽  
Yixin Zhang ◽  
Ting Long ◽  
Wei He ◽  
Guangcheng Qin ◽  
...  
Keyword(s):  
Chronic Migraine ◽  
Microglial Activation ◽  
Morphological Changes ◽  
Critical Role ◽  
Radiant Heat ◽  
P2y12 Receptor ◽  
Trigeminal Nucleus ◽  
Double Labeling ◽  
Trigeminal Nucleus Caudalis

Abstract Background Microglial activation contributes to the development of chronic migraine (CM). The P2Y12 receptor (P2Y12R), a metabolic purinoceptor that is expressed on microglia in the central nervous system (CNS), has been indicated to play a critical role in the pathogenesis of chronic pain. However, whether it contributes to the mechanism of CM remains unknown. Thus, the present study investigated the precise details of microglial P2Y12R involvement in CM. Methods Mice subjected to recurrent nitroglycerin (NTG) treatment were used as the CM model. Hyperalgesia were assessed by mechanical withdrawal threshold to electronic von Frey and thermal withdrawal latency to radiant heat. Western blot and immunohistochemical analyses were employed to detect the expression of P2Y12R, Iba-1, RhoA, and ROCK2 in the trigeminal nucleus caudalis (TNC). To confirm the role of P2Y12R and RhoA/ROCK in CM, we systemically administered P2Y12R antagonists (MRS2395 and clopidogrel) and a ROCK2 inhibitor (fasudil) and investigated their effects on microglial activation, c-fos, and calcitonin gene-related peptide (CGRP) expression in the TNC. To further confirm the effect of P2Y12R on microglial activation, we preincubated lipopolysaccharide (LPS)-treated BV-2 microglia with MRS2395 and clopidogrel. ELISA was used to evaluate the levels of inflammatory cytokines. Results The protein levels of P2Y12R, GTP-RhoA, ROCK2, CGRP, c-fos, and inducible nitric oxide synthase (iNOS) in the TNC were increased after recurrent NTG injection. A double labeling study showed that P2Y12R was restricted to microglia in the TNC. MRS2395 and clopidogrel attenuated the development of tactile allodynia and suppressed the expression of CGRP, c-fos, and GTP-RhoA/ROCK2 in the TNC. Furthermore, fasudil also prevented hyperalgesia and suppressed the expression of CGRP in the TNC. In addition, inhibiting P2Y12R and ROCK2 activities suppressed NTG-induced microglial morphological changes (process retraction) and iNOS production in the TNC. In vitro, a double labeling study showed that P2Y12R was colocalized with BV-2 cells, and the levels of iNOS, IL-1β, and TNF-α in LPS-stimulated BV-2 microglia were reduced by P2Y12R inhibitors. Conclusions These data demonstrate that microglial P2Y12R in the TNC plays a critical role in the pathogenesis of CM by regulating microglial activation in the TNC via RhoA/ROCK pathway.

scholarly journals Activation of microglial GLP-1R in the trigeminal nucleus caudalis suppresses central sensitization of chronic migraine after recurrent nitroglycerin stimulation

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Feng Jing ◽  
Qian Zou ◽  
Yangyang Wang ◽  
Zhiyou Cai ◽  
Yong Tang
Keyword(s):  
Chronic Migraine ◽  
Western Blotting ◽  
Central Sensitization ◽  
Microglial Activation ◽  
Morphological Changes ◽  
Trigeminal Nucleus ◽  
Trigeminal Nucleus Caudalis ◽  
Tnf Α

Abstract Background Central sensitization is considered a critical pathogenic mechanism of chronic migraine (CM). Activation of microglia in the trigeminal nucleus caudalis (TNC) contributes to this progression. Microglial glucagon-like peptide-1 receptor (GLP-1R) activation can alleviate pain; however, whether it is involved in the mechanism of CM has not been determined. Thus, this study aims to investigate the precise role of GLP-1R in the central sensitization of CM. Methods Repeated nitroglycerin injection-treated mice were used as a CM animal model in the experiment. To identify the distribution and cell localization of GLP-1R in the TNC, we performed immunofluorescence staining. Changes in the expression of GLP-1R, Iba-1, PI3K and p-Akt in the TNC were examined by western blotting. To confirm the effect of GLP-1R and PI3K/Akt in CM, a GLP-1R selective agonist (liraglutide) and antagonist (exendin(9–39)) and a PI3K selective antagonist (LY294002) were administered. Mechanical hypersensitivity was measured through von Frey filaments. To investigate the role of GLP-1R in central sensitization, calcitonin gene-related peptide (CGRP) and c-fos were determined using western blotting and immunofluorescence. To determine the changes in microglial activation, IL-1β and TNF-α were examined by western blotting, and the number and morphology of microglia were measured by immunofluorescence. We also confirmed the effect of GLP-1R on microglial activation in lipopolysaccharide-treated BV-2 microglia. Results The protein expression of GLP-1R was increased in the TNC after nitroglycerin injection. GLP-1R was colocalized with microglia and astrocytes in the TNC and was fully expressed in BV-2 microglia. The GLP-1R agonist liraglutide alleviated basal allodynia and suppressed the upregulation of CGRP, c-fos and PI3K/p-Akt in the TNC. Similarly, the PI3K inhibitor LY294002 prevented nitroglycerin-induced hyperalgesia. In addition, activating GLP-1R reduced Iba-1, IL-1β and TNF-α release and inhibited TNC microglial number and morphological changes (process retraction) following nitroglycerin administration. In vitro, the protein levels of IL-1β and TNF-α in lipopolysaccharide-stimulated BV-2 microglia were also decreased by liraglutide. Conclusions These findings suggest that microglial GLP-1R activation in the TNC may suppress the central sensitization of CM by regulating TNC microglial activation via the PI3K/Akt pathway.

scholarly journals P2X7R-mediated Autophagic Impairment Contributes to Central Sensitization in a chronic Migraine Model with Recurrent Nitroglycerin Stimulation in Mice

2020 ◽  
Author(s):  
Li Jiang ◽  
Yixin Zhang ◽  
Feng Jing ◽  
Ting Long ◽  
Guangcheng Qin ◽  
...  
Keyword(s):  
Chronic Migraine ◽  
Central Sensitization ◽  
Cellular Localization ◽  
Microglial Activation ◽  
Purinergic Receptor ◽  
Radiant Heat ◽  
Underlying Mechanism ◽  
Autophagic Flux ◽  
Pathophysiological Mechanism

Abstract Background: Central sensitization is an important pathophysiological mechanism of chronic migraine (CM). According to our previous studies, microglial activation and subsequent inflammation in the trigeminal nucleus caudalis (TNC) contribute to the central sensitization. The P2X7 receptor (P2X7R) is a purinergic receptor expressed in microglia and participates in central sensitization in chronic pain, but its role in CM is unclear. Numerous studies have shown that P2X7R regulates the level of autophagy and that autophagy affects the microglial activation and inflammation. Recently, autophagy has been shown to be involved in neuropathic pain, but there is no information about autophagy in CM. Therefore, the current study investigated the role of P2X7R in CM and its underlying mechanism, focusing on autophagy regulation.Methods: The CM model was established by repeated intraperitoneal injection of nitroglycerin (NTG) in mice. A Von Frey filament and radiant heat were used to assess the mechanical and thermal hypersensitivity. Western blotting and immunofluorescence assays were performed to detect the expression of P2X7R, autophagy-related proteins, and the cellular localization of P2X7R. To determine the role of P2X7R and autophagy in CM, we detected the effects of the autophagy inducer, rapamycin (RAPA) and P2X7R antagonist, Brilliant Blue G (BBG), on pain behavior and the expression of calcitonin gene-related peptide (CGRP) and c-fos. In addition, the effect of RAPA and BBG on microglial activation and subsequent inflammation were investigated.Results: The expression of P2X7R was increased and was mainly colocalized with microglia in the TNC following recurrent NTG administration. The autophagic flux was blocked in CM, which was characterized by up-regulated LC3-II, and accumulated autophagy substrate protein, p62. RAPA significantly improved the basal rather than acute hyperalgesia. BBG alleviated both basal and acute hyperalgesia. BBG activated the level of autophagic flux. RAPA and BBG inhibited the activation of microglia, limited the inflammatory response, and reduced the expression of CGRP and c-fos. Conclusions: Our results demonstrate the dysfunction of the autophagic process in CM. Activated autophagy may have a preventive effect on migraine chronification. P2X7R contributes to central sensitization through mediating autophagy regulation and might become a potential target for CM.

scholarly journals The Antioxidant Resveratrol Protects against Chondrocyte Apoptosis by Regulating the COX-2/NF-κB Pathway in Created Temporomandibular Osteoarthritis

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Wen Li ◽  
Shiyu Hu ◽  
Xuepeng Chen ◽  
Jiejun Shi
Keyword(s):  
Morphological Changes ◽  
Critical Role ◽  
Chondrocyte Apoptosis ◽  
Optimum Dose ◽  
Protective Effects ◽  
Condylar Cartilage ◽  
Temporomandibular Joint Osteoarthritis ◽  
Cox 2 ◽  
Antioxidant Effects

Temporomandibular joint osteoarthritis (TMJOA) is characterized by chronic inflammatory degradation of mandibular condylar cartilage (MCC). Studies have found a positive correlation between inflammation and cyclooxygenase- (COX-) 2 in OA pathology. NF-κB is a crucial transcription factor of inflammatory and immune responses in the cause of TMJOA pathology. Resveratrol (RES) plays a critical role in antioxidation and anti-inflammation. But, studies on the effects of RES on TMJOA are very limited. So, the purpose of this study is to investigate the antioxidant and protective effects of RES against MCC degradation through downregulating COX-2/NF-κB expression. In vitro studies, the MCC cells were divided into three groups: the NC group, OA group, and RES group. The optimum dose of RES (10 μM) was determined. The TMJOA model of mice was created by injection of collagenase. And mice were injected with RES (100 μg/10 μl) 3 times one week for 4 weeks in the RES group. The expressions of COX-2, P65, MMP1, MMP13, COL2, and ACAN were measured by RT-PCR. Morphological changes of MCC were studied with HE staining. The results showed that inflammation could induce MCC degradation in vitro and vivo, while RES could reverse the degradation. Meanwhile, RES could downregulate COX-2/NF-κB/MMP expression and increase cartilage markers in vitro and vivo studies. The results indicated that RES treatment had antioxidant effects against chondrocyte apoptosis by downregulating the COX-2/NF-κB pathway in created TMJOA.

scholarly journals Sensory nerves directly promote osteoclastogenesis by secreting Cyp40

2021 ◽  
Author(s):  
Guo-Xian Pei ◽  
Liu Yang ◽  
Junqin Li ◽  
Bin Liu ◽  
Hao Wu ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Repair ◽  
Bone Cells ◽  
Critical Role ◽  
Sensory Nerve ◽  
Sensory Nerves ◽  
Blue Staining ◽  
Double Labeling ◽  
Sensory Hypersensitivity

Abstract BackgroundGiven the afferent functions, sensors have been found exerting efferent influences and directly alter organ physiology. Sensory nerves have been found critical in osteoclasts and bone resorption. However, the direct evidence of whether sensory nerve efferent influences osteoclast, remains lacking. MethodsWe treated mice with resiniferatoxin (RTX) or complete Freund’s adjuvant (CFA) to induce sensory hypersensitivity. Bone histomorphometry including micro-ct, three-point bending assay, von kossa staining, calcein double labeling, toluidine blue staining, and trap staining were performed to monitor bone quality and bone cells. Multiple virus vectors were applied to trace signals between sensory nerves and osteoclasts. Sensory neurons (SN) and osteoclasts were cocultured to study the effects and mechanisms of the sensory nerves on osteoclasts in vitro. Isobaric tag for relative and absolute quantitation (iTRAQ) was used to identify secreted proteins in the sensory nerve. ResultsHere, we found sensory hypersensitivity significantly increased osteoclast bone resorption; SN directly promote osteoclastogenesis in vitro; and abundant sensory efferent signals transported into osteoclasts. Then our screening identified a novel neuropeptide Peptidyl-prolyl cis-trans isomerase D (Cyp40), is the reverse signal from the sensory nerve and plays a critical role for osteoclastogenesis, via aryl hydrocarbon receptor (AhR)-Ras/Raf-pErk-NFATc1 pathway. The efferent signals from sensory nerves tend to involves in the rapid feedback process: vast majority of sensory efferent signals (87.28%) present in fast-twitch myofibers. ConclusionThis study revealed a novel mechanism of sensory nerves on osteoclasts: the direct promotion of osteoclastogenesis by the Cyp40. This mechanism may represent a direct, and quick response of sensory nerves to the changes in bone. Targeting the Cyp40 could therefore be a strategy to promote bone repair at the early stage of bone injury.

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

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.

Partial ATP depletion induces Fas- and caspase-mediated apoptosis in MDCK cells

1999 ◽  
Vol 276 (6) ◽  
pp. F837-F846 ◽  
Author(s):  
L. Richard Feldenberg ◽  
Sundararajah Thevananther ◽  
Marcela del Rio ◽  
Maryely de Leon ◽  
Prasad Devarajan
Keyword(s):  
Dna Cleavage ◽  
Serine Proteases ◽  
Fas Ligand ◽  
Mdck Cells ◽  
Morphological Changes ◽  
Critical Role ◽  
Atp Depletion ◽  
Caspase 8 ◽  
Death Domain

Brief periods of in vitro hypoxia/ischemia induce apoptosis of cultured renal epithelial cells, but the underlying mechanisms remain unknown. We show that partial ATP depletion (≈10–65% of control) results in a duration-dependent induction of apoptosis in Madin-Darby canine kidney (MDCK) cells, as evidenced by internucleosomal DNA cleavage (DNA laddering and in situ nick end labeling), morphological changes (cell shrinkage), and plasma membrane alterations (externalization of phosphatidylserine). The ATP-depleted cells display a significant upregulation of Fas, Fas ligand, and the Fas-associating protein with death domain (FADD). Exogenous application of stimulatory Fas monoclonal antibodies also induces apoptosis in nonischemic MDCK cells, indicating that they retain Fas-dependent pathways of programmed cell death. Furthermore, cleavage of poly(ADP)ribose polymerase (PARP) is evident after ATP depletion, indicating activation of caspases. Indeed, the apoptotic cells display a significant increase in caspase-8 (FLICE) activity. Finally, apoptosis induced by ATP depletion is ameliorated by pretreatment with inhibitors of caspase-8 (IETD), caspase-1 (YVAD), or caspase-3 (DEVD) but is not affected by inhibitors of serine proteases (TPCK). Our results indicate that partial ATP depletion of MDCK cells results in apoptosis and that Fas- and caspase-mediated pathways may play a critical role.

Activation of SIRT1 Alleviates Mitochondrial Dysfunction in The Trigeminal Nucleus Caudalis in a Rat Model of Chronic Migraine

2020 ◽  
Author(s):  
jie liang ◽  
xue zhou ◽  
jiang wang ◽  
zhaoyang fei ◽  
guangcheng qin ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Chronic Migraine ◽  
Rat Model ◽  
Vital Role ◽  
Peroxisome Proliferator ◽  
Trigeminal Nucleus ◽  
Peroxisome Proliferator Activated Receptor ◽  
Nuclear Respiratory Factor ◽  
Trigeminal Nucleus Caudalis ◽  
Nuclear Respiratory Factor 1

Abstract Background: The mechanism of chronic migraine (CM) is still unclear and mitochondrial dysfunction plays a possible role in migraine pathophysiology. Silent information regulator 1 (SIRT1) plays a vital role in mitochondrial dysfunction in many diseases, but there is no information about SIRT1 in CM.The aim of this study was to explore the role of SIRT1 in mitochondrial dysfunction in CM. Methods： A rat model was established through repeated dural infusions of inflammatory soup (IS) for seven days to simulate CM attacks. Cutaneous hyperalgesia caused by the repeated infusions of IS was detected using the von Frey test. Then, we detected SIRT1 expression in the trigeminal nucleus caudalis (TNC). To explore the effect of SIRT1 on mitochondrial dysfunction in CM rats, we examined whether SRT1720, an activator of SIRT1, altered mitochondrial dysfunction in CM rats. Results： Repeated infusions of IS resulted in cutaneous hyperalgesia accompanied bydownregulation of SIRT1.SRT1720 significantly alleviated the cutaneous hyperalgesia induced by repeated infusions of IS. Furthermore, activation of SIRT1 markedly increased the expression of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha(PGC-1α), transcription factor A (TFAM), nuclear respiratory factor 1 (NRF-1), and nuclear respiratory factor 2(NRF-2) mitochondrial DNA (mtDNA) and increased the ATP content and mitochondrial membrane potential. Conclusions ：Our results indicate that SIRT1 may have an effect on mitochondrial dysfunction in CM rats. Activation of SIRT1 has a protective effect on mitochondrial function in CM rats.

scholarly journals Fra-1 Induces Morphological Transformation and Increases In Vitro Invasiveness and Motility of Epithelioid Adenocarcinoma Cells

1998 ◽  
Vol 18 (12) ◽  
pp. 7095-7105 ◽  
Author(s):  
Olga Kustikova ◽  
Dmitrii Kramerov ◽  
Mariam Grigorian ◽  
Vladimir Berezin ◽  
Elisabeth Bock ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Cell Lines ◽  
Transcriptional Activation ◽  
Morphological Changes ◽  
Critical Role ◽  
Morphological Transformation ◽  
Morphological Alterations ◽  
Nuclear Extracts

ABSTRACT Two cell lines originating from a common ancestral tumor, CSML0 and CSML100, were used as a model to study AP-1 transcription factors at different steps of tumor progression. CSML0 cells have an epithelial morphology; they express epithelial but not mesenchymal markers and are invasive neither in vitro nor in vivo. CSML100 possesses all characteristics of a highly progressive carcinoma. These cells do not form tight contacts, are highly invasive in vitro, and are metastatic in vivo. AP-1 activity was considerably higher in CSML100 cells than in CSML0 cells. There was a common predominant Jun component, namely, JunD, detected in both cell lines. We found that the enhanced level of AP-1 in CSML100 cells was due to high expression of Fra-1 and Fra-2 proteins, which were undetectable in CSML0 nuclear extracts. Analysis of the transcription of different AP-1 members in various cell lines derived from tumors of epithelial origin revealed a correlation of fra-1 expression with mesenchymal characteristics of carcinoma cells. Moreover, we show here for the first time that the expression of exogenous Fra-1 in epithelioid cells results in morphological changes that resemble fibroblastoid conversion. Cells acquire an elongated shape and become more motile and invasive in vitro. Morphological alterations were accompanied by transcriptional activation of certain genes whose expression is often induced at late stages of tumor progression. These data suggest a critical role of the Fra-1 protein in the development of epithelial tumors.

Direct Evidence for Central Sites of Action of Zolmitriptan (311C90)

Cephalalgia ◽  
1997 ◽  
Vol 17 (3) ◽  
pp. 153-158 ◽  
Author(s):  
PJ Goadsby ◽  
YE Knight
Keyword(s):  
Ex Vivo ◽  
Cervical Spinal Cord ◽  
Specific Binding ◽  
Femoral Vein ◽  
Brain Slices ◽  
Trigeminal Nucleus ◽  
Trigeminal Nucleus Caudalis ◽  
Dorsal Horns ◽  
Sites Of Action

The trigeminovascular system consists of bipolar neurons which innervate pain-sensitive intracranial structures and projecting to neurons in the superficial laminae of the caudal trigeminal nucleus and of the dorsal horns of C1 and C2. The serotonin (5HT1B/D) agonist zolmitriptan (311C90) has been shown to be effective in the treatment of acute attacks of migraine and experimental data suggest that it may have both peripheral and central sites of action. This study sought to further investigate possible central effects of zolmitriptan (311C90) by examining its distribution in the central nervous system. Specific binding of [3H]-zolmitriptan was determined both ex vivo and in vitro in the cat brain. For the ex vivo studies, cats were anaesthetized with halothane and -chloralose (60 mg/kg intraperitoneal). A femoral vein catheter was inserted for injection of the [3H]-zolmitriptan and then 1 h after injection the brain removed. For the in vitro studies fresh frozen brain slices were incubated with labelled and masking concentrations of zolmitriptan. The distribution of [3H]-zolmitriptan was determined using quantitative autoradiographic methods. The in vitro work demonstrated specific binding of [3H]-zolmitriptan in the superficial laminae of the trigeminal nucleus caudalis and dorsal horns of the C and C2 cervical spinal cord. The density of binding was 53 9 fmol/mg for the trigeminal nucleus caudalis, 47 7 fmol/mg for C1 and 50 6 fmol/mg for C2. The ex vivo work demonstrated binding in anatomically identical areas which was less dense than that seen with the in vitro method. These data confirm the existence of a population of receptors that specifically bind zolmitriptan following systemic administration. These receptors may, in part, be responsible for its clinical efficacy and reinforce the importance of central trigeminal neurons as a possible site of action of anti-migraine drugs.

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