A rapid simultaneous detection of duck hepatitis A virus 3 and novel duck reovirus based on RPA CRISPR Cas12a/Cas13a.

The mixed infection of duck hepatitis A virus 3 (DHAV-3) and novel duck reovirus (NDRV) has caused significant losses to the global duck farming industry. On-site point-of-care testing of viruses plays a crucial role in the early diagnosis, prevention, and disease control. Here, we proposed an RPA-CRISPR Cas12a/Cas13a one-pot strategy (DRCFS) for rapid and simultaneous detection of DHAV-3 and NDRV. This method integrated the reaction of RPA and CRISPR Cas12a/Cas13a in a single tube, eliminating the need to open the lid during the intermediate processes and thereby avoiding aerosol contamination. On this basis, we proposed a dual RPA-CRISPR strategy coupled with a lateral flow analysis platform (DRC-LFA). This circumvented the necessity for complex instruments, enabling direct visual interpretation of results, making the test more accessible and user-friendly. Our findings demonstrated that the DRCFS method could detect DHAV-3 and NDRV at concentrations as low as 100 copy/µL, while DRC-LFA achieved limit of 101 copies/µL within 35 min. Furthermore, when DRCFS, DRC-LFA, and qPCR were employed collectively for clinical samples analysis, all three methods yielded consistent results. The specificity, sensitivity, and user-friendly of these methods rendered them invaluable for on-site virus detection.

Common carp Peptidoglycan Recognition Protein 2 (CcPGRP2) plays a role in innate immunity for defense against bacterial infections.

PGRP is a family of pattern recognition molecules of the innate immune system. PGRPs are conserved from insects to mammals and have diverse functions in antimicrobial defense. Here we cloned a common carp PGRP ortholog, CcPGRP2 containing a conserved C-terminal PGRP domain. We tested the expression levels of CcPGRP2 in the liver, spleen, kidney, foregut, midgut, and hindgut of the highest level in the liver. The expression of CcPGRP2 upregulated in common carp infected with Aeromonas hydrophila (A. hydrophila) or Staphylococcus aureus (S. aureus). Recombinant CcPGRP2 protein expressed in Escherichia coli (E. coli) system and the purified CcPGRP2 could maintain the integrity of intestinal mucosa of common carp infected with A. hydrophila. In addition, CcPGRP2 could agglutinate or bind both gram-positive and gram-negative bacteria in a Zn2+-dependent manner. CcPGRP2 has a stronger agglutination and bacterial binding ability in gram-positive bacteria than in gram-negative bacteria. It is perhaps because CcPGRP2 could bind peptidoglycan (PGN) with a higher degree to lipopolysaccharide (LPS). And CcPGRP2 shows antimicrobial activities in the presence of Zn2+. Our results of CcPGRP2 provided new insight into the function of PGRP in the innate immunity of the common carp.

Chemical composition and therapeutic mechanism of Xuanbai Chengqi Decoction in the treatment of COVID-19 by network pharmacology, molecular docking and molecular dynamic analysis.

Xuanbai Chengqi Decoction (XBCQD), a classic traditional Chinese medicine, has been widely used to treat COVID-19 in China with remarkable curative effect. However, the chemical composition and potential therapeutic mechanism is still unknown. Here, we used multiple open-source databases and literature mining to select compounds and potential targets for XBCQD. The COVID-19 related targets were collected from GeneCards and NCBI gene databases. After identifying putative targets of XBCQD for the treatment of COVID-19, PPI network was constructed by STRING database. The hub targets were extracted by Cytoscape 3.7.2 and MCODE analysis was carried out to extract modules in the PPI network. R 3.6.3 was used for GO enrichment and KEGG pathway analysis. The effective compounds were obtained via network pharmacology and bioinformatics analysis. Drug-likeness analysis and ADMET assessments were performed to select core compounds. Moreover, interactions between core compounds and hub targets were investigated through molecular docking, molecular dynamic (MD) simulations and MM-PBSA calculations. As a result, we collected 638 targets from 61 compounds of XBCQD and 845 COVID-19 related targets, of which 79 were putative targets. Based on the bioinformatics analysis, 10 core compounds and 34 hub targets of XBCQD for the treatment of COVID-19 were successfully screened. The enrichment analysis of GO and KEGG indicated that XBCQD mainly exerted therapeutic effects on COVID-19 by regulating signal pathways related to viral infection and inflammatory response. Meanwhile, the results of molecular docking showed that there was a stable binding between the core compounds and hub targets. Moreover, MD simulations and MM-PBSA analyses revealed that these compounds exhibited stable conformations and interacted well with hub targets during the simulations. In conclusion, our research comprehensively explained the multi-component, multi-target, and multi-pathway intervention mechanism of XBCQD in the treatment of COVID-19, which provided evidence and new insights for further research.

Network pharmacology of iridoid glycosides from Eucommia ulmoides Oliver against osteoporosis.

Eucommia ulmoides Oliver is one of the commonly used traditional Chinese medicines for the treatment of osteoporosis, and iridoid glycosides are considered to be its active ingredients against osteoporosis. This study aims to clarify the chemical components and molecular mechanism of iridoid glycosides of Eucommia ulmoides Oliver in the treatment of osteoporosis by integrating network pharmacology and molecular simulations. The active iridoid glycosides and their potential targets were retrieved from text mining as well as Swiss Target Prediction, TargetNet database, and STITCH databases. At the same time, DisGeNET, GeneCards, and Therapeutic Target Database were used to search for the targets associated with osteoporosis. A protein-protein interaction network was built to analyze the interactions between targets. Then, DAVID bioinformatics resources and R 3.6.3 project were used to carry out Gene Ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis. Moreover, interactions between active compounds and potential targets were investigated through molecular docking, molecular dynamic simulation, and binding free energy analysis. The results showed that a total of 12 iridoid glycosides were identified as the active iridoid glycosides of Eucommia ulmoides Oliver in the treatment of osteoporosis. Among them, aucubin, reptoside, geniposide and ajugoside were the core compounds. The enrichment analysis suggested iridoid glycosides of Eucommia ulmoides Oliver prevented osteoporosis mainly through PI3K-Akt signaling pathway, MAPK signaling pathway and Estrogen signaling pathway. Molecular docking results indicated that the 12 iridoid glycosides had good binding ability with 25 hub target proteins, which played a critical role in the treatment of osteoporosis. Molecular dynamic and molecular mechanics Poisson-Boltzmann surface area results revealed these compounds showed stable binding to the active sites of the target proteins during the simulations. In conclusion, our research demonstrated that iridoid glycosides of Eucommia ulmoides Oliver in the treatment of osteoporosis involved a multi-component, multi-target and multi-pathway mechanism, which provided new suggestions and theoretical support for treating osteoporosis.

Exploring the potential therapeutic effect of Eucommia ulmoides-Dipsaci Radix herbal pair on osteoporosis based on network pharmacology and molecular docking technology.

Eucommia ulmoides-Dipsaci Radix (EU-DR) is a commonly used herbal pair for the treatment of osteoporosis (OP) in China. The purpose of this study was to investigate the potential mechanism of EU-DR on OP through network pharmacology and molecular docking approaches. Combining data from multiple open-source databases and literature mining, the active compounds and potential targets of EU-DR were screened out. The OP related targets were identified from the interactive web tool GEO2R. The shared targets were obtained by intersecting the targets of EU-DR and OP. The protein-protein interaction (PPI) network was constructed via the STRING database and Cytoscape 3.7.2 software. GO and KEGG enrichment analysis were conducted using R 3.6.3 software with adjusted p-value < 0.05. Sybyl-x 2.1.1 and Autodock Vina 1.1.2 software were used to cross validate the affinity between active compounds and target proteins. Our results showed that a total of 50 active compounds were screened, corresponding to 895 EU-DR targets, 2202 OP targets and 144 shared targets. The flavonoids in EU-DR played an important role in anti-OP. The enrichment analysis of GO and KEGG suggested EU-DR exerted a therapeutic effect on OP mainly by regulating the osteoclast differentiation related signaling pathway. Meanwhile, molecular docking results showed that most active compounds in EU-DR had strong binding efficiency to the target proteins. In conclusion, this study elaborated the multi-component, multi-target, and multi-pathway interaction mechanism of the EU-DR herbal pair in the treatment of OP for the first time, which also provided a pharmacological basis for treating OP.

Recombinase polymerase amplification assay for rapid detection of Seneca Valley Virus.

Seneca Valley virus (SVV) is related to vesicular disease in pigs, and its clinical symptoms are indistinguishable from other notifiable clinical symptoms of vesicular disease such as foot-and-mouth disease. The rapid and accurate detection of SVV is essential to confirm the pathogenic factors and initiate the implementation of control measures. The development of a rapid, simple, convenient, and low-cost molecular (nucleic acid amplification) test that can be used at the sample collection point has been identified as a key component for controlling SVV. This study describes the development and demonstration of recombinase polymerase amplification (RPA) test targeting the conserved regions of SVV for detection of SVV. The Primers and probes designed by us have shown good sensitivity and specificity in RPA test, which is helpful for RPA to be an effective tool for rapid diagnosis of SVV.

Role of TRPV4-P2X7 Pathway in Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion.

Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel that is involved in the development of neuropathic pain. P2X7 receptor (P2X7) belongs to a class of ATP-gated nonselective cation channels that plays an important role in neuropathic pain. Nevertheless, little is known about the interaction between them for neuropathic pain. In this paper, we investigated role of TRPV4-P2X7 pathway in neuropathic pain. We evaluated the effect of TRPV4-P2X7 pathway on neuropathic pain in a chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) model. We analyzed the effect of P2X7 on mechanical and thermal hyperalgesia mediated by TRPV4 in CCD. Furthermore, we assessed the effect of TRPV4 on the expression of P2X7 and the release of IL-1ß and IL-6 in DRG after CCD. We found that intraperitoneal injection of TRPV4 agonist GSK-1016790A led to a significant increase of mechanical and thermal hyperalgesia in CCD, which was partially suppressed by P2X7 blockade with antagonist Brilliant Blue G (BBG). Then, we further noticed that GSK-1016790A injection increased the P2X7 expression of CCD, which was decreased by TRPV4 blockade with antagonist RN-1734 and HC-067047. Furthermore, we also discovered that the expressions of IL-1ß and IL-6 were upregulated by GSK-1016790A injection but reduced by RN-1734 and HC-067047. Our results provide evidence that P2X7 contributes to development of neuropathic pain mediated by TRPV4 in the CCD model, which may be the basis for treatment of neuropathic pain relief.

Curcumin alleviates OGD/R-induced PC12 cell damage via repressing CCL3 and inactivating TLR4/MyD88/MAPK/NF-κB to suppress inflammation and apoptosis.

OBJECTIVES: Curcumin presents some therapeutic effects including anti-cancer and anti-inflammation. Herein, we centred on the functional role of curcumin in cerebral ischaemia injury and its potential molecular mechanisms. METHODS: Microarray analysis was used for excavating crucial genes in cerebral ischaemia. PC12 cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD/R) to imitate cerebral ischaemia/reperfusion (I/R) injury in vitro. Cell viability and apoptosis abilities were evaluated by Cell Counting Kit-8 and flow cytometry assays. qRT-PCR, Western blot and enzyme-linked immunosorbent assays were performed to assess the concentrations of related genes. KEY FINDINGS: By enquiring GEO dataset, C-C motif chemokine ligand 3 (CCL3) was profoundly upregulated in cerebral I/R injury model. And CCL3 was found to be highly expressed in PC12 cells suffered from OGD/R. Moreover, we found that CCL3 was a potential target of curcumin in cerebral I/R injury. More importantly, the following experiments illustrated that curcumin inhibited the expression of CCL3 in OGD/R model and reduced cell apoptosis and inflammation. Moreover, high expression levels of TLR4, MyD88, p-NF-κB P65, p-P38 MAPK and p-IκBα in OGD/R model were inhibited by curcumin. CONCLUSIONS: Our study manifested that curcumin might be a meritorious drug for the treatment of cerebral ischaemia by acting on CCL3.

Curcumin alleviates pain and improves cognitive impairment in a rat model of cobra venom-induced trigeminal neuralgia.

BACKGROUND: Cognitive impairment is a common complication in patients with chronic neuropathic pain, without effective therapy. Recent works have indicated that curcumin (Cur) possesses antinociceptive and neuroprotective potentials, suggesting its possible effectiveness for the treatment of this complication. OBJECTIVE: The aim of this study was to explore the effects of Cur on pain behaviors and cognitive impairment in rats with cobra venom-induced trigeminal neuralgia (TN). DESIGN: This is a randomized, controlled experiment. SETTING: This study was conducted at the Experimental Animal Center, Beijing Friendship Hospital, Capital Medical University. SUBJECTS: A total of 40 adult male Sprague Dawley rats were used in this study. METHODS: A cobra venom solution was injected into the sheath of infraorbital nerve. Cur was administered intragastrically at 45 mg/kg twice daily for 28 successive days from postoperative day 15. Mechanical allodynia was evaluated using von Frey filaments. Free behaviors were observed using video recording. Cognitive capacity was tested using the Morris water maze. Both morphology and ultrastructure of the CA1 hippocampal region were visualized using hematoxylin and eosin (HE) staining and transmission electron microscopy, respectively. RESULTS: Cur treatment reduced mechanical allodynia and face-grooming activities but increased exploratory activities and improved spatial learning and memory deficits. Microscopic examination revealed nucleus pyknosis, swollen organelles, and decreased synapse density in the CA1 hippocampal region after cobra venom injection. However, chronic Cur treatment reversed damage to hippocampal neurons and synapses. CONCLUSION: Cur can alleviate pain, improve spatial learning and memory deficits, and restore the damage to hippocampal neurons and synapses in cobra venom-induced TN rats. Cur may be useful as an adjuvant to treat chronic neuropathic pain-induced cognitive deficits.

Trigeminal Neuralgia Induced by Cobra Venom Leads to Cognitive Deficits Associated with Downregulation of CREB/BDNF Pathway.

BACKGROUND: Chronic pain often results in cognitive impairment. Our previous study showed that trigeminal neuralgia induced by cobra venom leads to spatial learning and memory deficits, although the underlying mechanism remains unclear. However, recent evidence indicates that the c-AMP-responsive element binding protein (CREB)/brain derived neurotrophic factor (BDNF) pathway plays a critical role in various etiologies of cognitive deficits. OBJECTIVES: Our aim was to explore the CREB/BDNF pathway to determine the molecular mechanisms involved in the pathogenesis of cognitive impairment caused by cobra venom-induced trigeminal neuralgia. STUDY DESIGN: A randomized, controlled animal study. SETTING: Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University. METHODS: Fifty male Sprague-Dawley rats were randomly divided into 3 groups: cobra venom group, sham group, and control group. Cobra venom or saline was injected into the sheath of the infraorbital nerve (ION), respectively. Video recordings and mechanical thresholds were used to analyze changes in behavioral activity 3 days before surgery and 4, 7, 14, 21, 28, and 56 days after surgery. Morris water maze tests were conducted at 4- and 8-week time points after surgery to evaluate spatial learning and memory. We also investigated expression changes of phosphorylated CREB (p-CREB) and BDNF in the hippocampus and prefrontal cortex (PFC) using western blotting and immunohistochemistry. RESULTS: Cobra venom-treated rats exhibited significant changes in face grooming, as well as exploratory and resting behaviors, compared with the control group and sham group (both P < 0.001). Rats in the cobra venom group exhibited slightly impaired acquisition (P < 0.05) without memory deficits (P > 0.05) in the first water maze protocol. In the second water maze test, rats in the cobra venom group exhibited spatial learning and memory deficits, with fewer platform site crossings during the probe trial (P < 0.05). Moreover, results showed decreased p-CREB and BDNF expressions in the hippocampus and PFC in the cobra venom group, with significant differences at 9 weeks post-surgery (P < 0.05). LIMITATIONS: No signaling inhibitor or genetic manipulation was administered to further confirm upstream factors of the CREB/BDNF pathway in cognitive deficits caused by chronic trigeminal neuralgia. CONCLUSIONS: The findings suggest that cognitive impairment caused by cobra venom-induced trigeminal neuralgia is associated with downregulation of the CREB/BDNF pathway in the hippocampus and PFC.Key words: Cognitive impairment, the CREB/BDNF pathway, cobra venom, trigeminal neuralgia, hippocampus, prefrontal cortex, free behavior, Morris water maze.

Fluoroscopy-guided Bipolar Radiofrequency Thermocoagulation Treatment for Discogenic Low Back Pain.

BACKGROUND: The efficacy of percutaneous intradiscal radiofrequency thermocoagulation (PIRFT) for the treatment of discogenic low back pain (LBP) remains controversial. However, all the PIRFT studies utilized monopolar radiofrequency thermocoagulation (RFTC). The aim of this study was to investigate the safety and efficacy of bipolar RFTC for the treatment of discogenic LBP. METHODS: A total of 23 patients with discogenic LBP were treated with single-level bipolar RFTC. The patients were assessed before the procedure and at 1 week, 1 month, 3 months, 6 months, and 1 year after the procedure. The primary outcome included the visual analog scale (VAS) score and the Oswestry Disability Index (ODI) score. The secondary outcome included pain relief, reduction of analgesic dose, and patient satisfaction. RESULTS: The VAS and ODI scores were significantly decreased after bipolar RFTC treatment at all time points of follow-up (P < 0.05). Bipolar RFTC treatment also resulted in a significant change in all secondary measures, such as pain relief, reduction of analgesic dose, and patient satisfaction. No serious complications or neurological sequelae were observed in any of the patients. CONCLUSIONS: Bipolar RFTC treatment can significantly attenuate pain and improve the function of patients with discogenic LBP.

Effects of Chronic Alcohol Exposure on the Modulation of Ischemia-Induced Glutamate Release via Cannabinoid Receptors in the Dorsal Hippocampus.

BACKGROUND: Chronic alcohol consumption is a critical contributing factor to ischemic stroke, as it enhances ischemia-induced glutamate release, leading to more severe excitotoxicity and brain damage. But the neural mechanisms underlying this phenomenon are poorly understood. METHODS: We evaluated the effects of chronic alcohol exposure on the modulation of ischemia-induced glutamate release via CB1 and CB2 cannabinoid receptors during middle cerebral artery occlusion, using in vivo microdialysis coupled with high-performance liquid chromatography, in alcohol-naïve rats or rats after 1 or 30 days of withdrawal from chronic ethanol intake (6% v/v for 14 days). RESULTS: Intra-dorsal hippocampus (DH) infusions of ACEA or JWH133, selective CB1 or CB2 receptor agonists, respectively, decreased glutamate release in the DH in alcohol-naïve rats in a dose-dependent manner. Such an effect was reversed by co-infusions of SR141716A or AM630, selective CB1 or CB2 receptor antagonists, respectively. After 30 days, but not 1 day of withdrawal, ischemia induced an enhancement in glutamate release in the DH, as compared with non-alcohol-treated control group. Intra-DH infusions of JWH133, but not ACEA, inhibited ischemia-induced glutamate release in the DH after 30 days of withdrawal. Finally, 1 day of withdrawal did not alter the protein level of CB1 or CB2 receptors in the DH, as compared to non-alcohol-treated control rats. Whereas 30 days of withdrawal robustly decreased the protein level of CB1 receptors, but failed to alter the protein level of CB2 receptors, in the DH, as compared to non-alcohol-treated control rats. CONCLUSIONS: Together, these findings suggest that loss of expression/function of CB1 receptors, but not CB2 receptors in the DH, is correlated with the enhancement of ischemia-induced glutamate release after prolonged alcohol withdrawal.

Role of colchicine-induced microtubule depolymerization in hyperalgesia via TRPV4 in rats with chronic compression of the dorsal root ganglion.

The aim of this study is to investigate the effect of microtubule depolymerization by colchicine on hyperalgesia mediated by transient receptor potential vanilloid 4 (TRPV4) in a neuropathic pain model of chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) in rat. Intrathecal administration of microtubule-depolymerizing agent, colchicine, attenuated the activated effect of 4alpha-phorbol 12, 13-didecanoate (4alpha-PDD, TRPV4 specific agonist) on mechanical and thermal hyperalgesia in CCD rats. This observation is in agreement with our in vitro experiments with DRG cells that showed a significant attenuation of 4alpha-PDD-activated Ca(2+)-influx and substance P (SP) release with the colchicine treatment. We conclude that microtubule depolymerization by colchicine can regulate pain sensitivity by depressing the hyperalgesia mediated by TRPV4.

Functional interaction of TRPV4 channel protein with annexin A2 in DRG.

BACKGROUND: Transient receptor potential vanilloid 4 (TRPV4) is a Ca(2+)-permeable, non-selective cation channel that is involved in the transmission of pain signals mediated by dorsal root ganglion (DRG). Annexin A2 belongs to a class of membrane-binding proteins that plays an important role in the regulation of ion channels. Nevertheless, little is known about the interaction between them in DRG. In this paper, we evaluated the functional interaction of TRPV4 with annexin A2 in DRG. METHODS: We have used immunocytochemistry and co-immunoprecipitation assays to investigate the interaction between annexin A2 and TRPV4 in DRG. The role of annexin A2 in the regulation of TRPV4 activity in DRG was further verified by measurement of intracellular free calcium concentrations ([Ca(2+)](i)) and substance P (SP) release. RESULTS: First, annexin A2 was showed partial co-localization with TRPV4 in DRG neurons. Then, annexin A2 and TRPV4 were co-precipitated with each other in DRG lysates. Furthermore, the downregulation of annexin A2 using specific small interfering RNA significantly inhibited Ca(2+) influx and SP mediated by TRPV4. CONCLUSION: Our results provide evidence that annexin A2 is associated with TRPV4 and regulates TRPV4-mediated Ca(2+) influx and SP release in DRG neurons. The objective of this work is to determine the influence of annexin A2 on TRPV4 in DRG neurons, which may be the basis for treatment of pain relief.

Nuclear factor-kappa B mediates TRPV4-NO pathway involved in thermal hyperalgesia following chronic compression of the dorsal root ganglion in rats.

The aim of this study was to test the hypothesis that nuclear factor-kappa B (NF-κB) is involved in TRPV4-NO pathway in thermal hyperalgesia following chronic compression of the dorsal root ganglion (DRG) (the procedure hereafter termed CCD) in rat. Intrathecal administration of two NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC; 10(-1) to 10(-2)M) and BAY (100-50 µM), both induced significantly dose-dependent increase in the paw withdrawal latency (PWL) and decrease in nitric oxide (NO) content in DRG when compared with control rats. Pretreatment with 4α-phorbol 12,13-didecanoate (4α-PDD, transient receptor potential vanilloid 4 (TRPV4) synthetic activator, 1 nm) attenuated the suppressive effects of PDTC (10(-1)M) and BAY (100 µM) on CCD-induced thermal hyperalgesia and NO production. In addition, Western blot analysis indicated that CCD rats exhibited nuclear NF-κB protein expression and low levels of cytoplasmic inhibitory-kappa B (I-κB) expression; the increase in NF-κB expression and decrease in I-κB expression were reversed after intrathecal injection of PDTC. In conclusion, our data suggested that NF-κB could be involved in TRPV4-NO pathway in CCD-induced thermal hyperalgesia.

Involvement of TRPV4-NO-cGMP-PKG pathways in the development of thermal hyperalgesia following chronic compression of the dorsal root ganglion in rats.

The aim of the present study was to test the hypothesis that the TRPV4-NO-cGMP-PKG cascade is involved in the maintenance of thermal hyperalgesia following chronic compression of the dorsal root ganglion (DRG) (the procedure hereafter termed CCD) in rats. CCD rats showed thermal hyperalgesia and increased nitrite production. Intrathecal administration of ruthenium red (TRPV4 antagonist, 0.1-1 nmol), TRPV4 antisense ODN (TRPV4 AS, 40 microg, daily for 7 days), N(G)-L-nitro-arginine methyl ester (l-NAME, inhibitor of NO synthase, 30-300 nmol), 1H-[1,2,4]-oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, a soluble guanylate cyclase inhibitor, 50-100 nmol) or 8-(4-Chlorophenylthio) guanosine 3',5'-cyclic Monophosphothioate, Rp-Isomer sodium salt (Rp-8-pCPT-cGMPS, a PKG inhibitor, 25-50 nmol) induced a significant (P<0.001) and dose-dependent increase in the paw withdrawal latency (PWL) compared with control rats, respectively. Ruthenium red (1 nmol), TRPV4 AS (40 microg, daily for 7 days) or L-NAME (300 nmol) decreased nitrite (an index of nitric oxide formation) in the DRG of CCD rats. In addition, the phorbol ester 4alpha-phorbol 12,13-didecanoate (4alpha-PDD, TRPV4 synthetic activator, 1 nmol), co-administered with L-NAME (300 nmol), attenuated the suppressive effect of L-NAME on CCD-induced thermal hyperalgesia and nitrite production. Our data suggested that the TRPV4-NO-cGMP-PKG pathway could be involved in CCD-induced thermal hyperalgesia.

Ischemic compression block attenuates mechanical hyperalgesia evoked from latent myofascial trigger points.

The aim of the present study is to test the hypothesis that large-diameter myelinated muscle afferents contribute to the pathophysiology of myofascial trigger points (MTrPs). The ischemic compression blockage (ICB) of large-diameter myelinated muscle afferents was obtained with a 7-cm-wide tourniquet applied around the upper arm proximal to the brachioradialis muscle in 20 healthy subjects. This study consisted of two randomized sessions with an interval of 1 week in between each session. In one session, pressure pain threshold (PPT) and pressure threshold for eliciting referred pain (PTRP) were measured at an MTrP region in the brachioradialis muscle in one forearm. In another session, PPT was measured at a non-MTrP region in the brachioradialis muscle of the contralateral forearm at the time of pre-compression, 20 min following compression, and 10 min after decompression. The results showed that ICB, which mainly blocks large-diameter myelinated muscle afferents, was associated with an increase in PPT and PTRP (all P < 0.001) at MTrP regions but not at non-MTrP regions. These results suggest that large-diameter muscle afferents may be involved in pain and mechanical hyperalgesia at MTrPs.