Emodin Down-Regulates Expression of TRPV1 mRNA and Its Function in DRG Neurons in Vitro

Emodin is a principle ingredient isolated from rhubarb rhizome, which is commonly used for constipation or pain-related diseases in traditional Chinese medicine (TCM) practice. The transient receptor potential vanilloid 1 ion channel proteins (TRPV1) are abundantly expressed in the peripheral sensory neurons and are assumed to act as a kind of nociceptor involved in the perception of pain and development of hyperalgesia. The aim of this study was to further unravel the analgesic mechanisms of rhubarb through investigating the effects of its main constitutive ingredient emodin on the expression of TRPV1 mRNA as well as on its calcium- mediating functions in vitro. The primary DRG neurons with a high purity and viability were obtained, and the TRPV1 mRNA expression levels were examined by using real-time RT-PCR and the elevated amplitudes of intracellular [ Ca2+ ] i in the DRG neurons evoked by TRPV1 agonist capsaicin were examined by confocal microscopy. The results showed that emodin could significantly down-regulate both the mRNA expression of TRPV1 and the capsaicin-evoked intracellular fluorescent intensity in the DRG neurons under both 37°C and 39°C in vitro. Concomitantly, all of the changes induced by emodin could not be blocked by pretreatment of the primary neurons with capsazepine, an antagonist of TRPV1. In conclusion, we established that the mRNA expression level of TRPV1 and its calcium-mediating function in naive DRG neurons could be down-regulated by emodin through perhaps the non-TRPV1 channel pathways, and this might be the molecular mechanisms for rhubarb to inhibit hyperalgesia induced by inflammatory stimuli.

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The mechanisms of protease-activated receptor 2 in mediating pain behaviors through nonselective cation channel signaling

10.21203/rs.2.19972/v1 ◽

2020 ◽

Author(s):

Yaping Yue ◽

Na Wang ◽

Yanming Lau ◽

Yiran Fu ◽

Hao Li ◽

...

Keyword(s):

Signaling Pathway ◽

Mechanical Allodynia ◽

Transient Receptor Potential ◽

Thermal Hyperalgesia ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Pain Behaviors ◽

Transient Receptor

Abstract Background: Activation of purinergic receptor P2X ligand-gated ion channel 3 (P2X3), transient receptor potential vanilloid type 1 (TRPV1), and transient receptor potential ankyrin 1 (TRPA1) by their specific ligands is a major mechanism contributing to magnified pain responses. The relationship between these nonselective cation channels and proteinase-activated receptor 2 (PAR2) activation mediated pain is still to be clarified.Methods: In this study, both in vitro model of dorsal root ganglion (DRG) neurons with PAR2 agonist SL-NH2 challenge and SL-NH2-induced pain rat model were used to approach these questions. The expression of P2X3, TRPV1, and TRPA1 in DRG neurons was investigated by quantitative real-time RT-PCR, Western blot, and immunofluorescence. The involvement of the PLCβ3/PKCε signaling pathway was also determined. The behavior test for mechanical allodynia and thermal hyperalgesia was performed. Results: SL-NH2 induced upregulation of P2X3, TRPV1, and TRPA1 through phosphorylation of phospholipase Cβ3 (PLCβ3) and protein kinase Cε (PKCε) signaling pathway in DRG neurons in vitro and in vivo. SL-NH2 also elevated the proportion of P2X3-, TRPV1-, and TRPA1-expressing neurons. The upregulation of P2X3, TRPV1, and TRPA1 and phosphorylation of PLCβ3 and PKCε in DRG neurons was paralleled with mechanical allodynia and thermal hyperalgesia behaviors in rats. Conclusions: The data of the present study imply that SL-NH2 as a noxious stimulus activates PAR2 which induces TRPV1, TRPA1, and P2X3 upregulation through PLCβ3/PKCε signaling pathway, thereby decreasing activation thresholds and increasing excitability, resulting in sustained nociceptive activity in DRG neurons, and then causing mechanical allodynia and thermal hyperalgesia behaviors. These data expanded our knowledge about PAR2-mediated pain sensitivity and its relationship with TRPV1, TRPA1, and P2X3 and provided new opportunities on management of pain behaviors.

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Effect of resolvins on sensitisation of TRPV1 and visceral hypersensitivity in IBS

Gut ◽

10.1136/gutjnl-2020-321530 ◽

2020 ◽

pp. gutjnl-2020-321530

Author(s):

Eluisa Perna ◽

Javier Aguilera-Lizarraga ◽

Morgane V Florens ◽

Piyush Jain ◽

Stavroula A Theofanous ◽

...

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Visceral Hypersensitivity ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Somatic Pain ◽

Protein Receptor ◽

Transient Receptor

ObjectiveResolvins (RvD1, RvD2 and RvE1) are endogenous anti-inflammatory lipid mediators that display potent analgesic properties in somatic pain by modulating transient receptor potential vanilloid 1 (TRPV1) activation. To what extent these molecules could also have a beneficial effect on TRPV1 sensitisation and visceral hypersensitivity (VHS), mechanisms involved in IBS, remains unknown.DesignThe effect of RvD1, RvD2 and RvE1 on TRPV1 activation and sensitisation by histamine or IBS supernatants was assessed on murine dorsal root ganglion (DRG) neurons using live Ca2+ imaging. Based on the results obtained in vitro, we further studied the effect of RvD2 in vivo using a murine model of post-infectious IBS and a rat model of post-inflammatory VHS. Finally, we also tested the effect of RvD2 on submucosal neurons in rectal biopsies of patients with IBS.ResultsRvD1, RvD2 and RvE1 prevented histamine-induced TRPV1 sensitisation in DRG neurons at doses devoid of an analgesic effect. Of note, RvD2 also reversed TRPV1 sensitisation by histamine and IBS supernatant. This effect was blocked by the G protein receptor 18 (GPR18) antagonist O-1918 (3–30 µM) and by pertussis toxin. In addition, RvD2 reduced the capsaicin-induced Ca2+ response of rectal submucosal neurons of patients with IBS. Finally, treatment with RvD2 normalised pain responses to colorectal distention in both preclinical models of VHS.ConclusionsOur data suggest that RvD2 and GPR18 agonists may represent interesting novel compounds to be further evaluated as treatment for IBS.

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Novel role of transient receptor potential vanilloid 2 in the regulation of cardiac performance

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00854.2013 ◽

2014 ◽

Vol 306 (4) ◽

pp. H574-H584 ◽

Cited By ~ 44

Author(s):

Jack Rubinstein ◽

Valerie M. Lasko ◽

Sheryl E. Koch ◽

Vivek P. Singh ◽

Vinicius Carreira ◽

...

Keyword(s):

Vascular Function ◽

Transient Receptor Potential ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Wild Type ◽

Transient Receptor ◽

Systolic And Diastolic Function ◽

Myocyte Contractility

Transient receptor potential cation channels have been implicated in the regulation of cardiovascular function, but only recently has our laboratory described the vanilloid-2 subtype (TRPV2) in the cardiomyocyte, though its exact mechanism of action has not yet been established. This study tests the hypothesis that TRPV2 plays an important role in regulating myocyte contractility under physiological conditions. Therefore, we measured cardiac and vascular function in wild-type and TRPV2−/− mice in vitro and in vivo and found that TRPV2 deletion resulted in a decrease in basal systolic and diastolic function without affecting loading conditions or vascular tone. TRPV2 stimulation with probenecid, a relatively selective TRPV2 agonist, caused an increase in both inotropy and lusitropy in wild-type mice that was blunted in TRPV2−/− mice. We examined the mechanism of TRPV2 inotropy/lusitropy in isolated myocytes and found that it modulates Ca2+ transients and sarcoplasmic reticulum Ca2+ loading. We show that the activity of this channel is necessary for normal cardiac function and that there is increased contractility in response to agonism of TRPV2 with probenecid.

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Eugenol Inhibits Sodium Currents in Dental Afferent Neurons

Journal of Dental Research ◽

10.1177/154405910608501005 ◽

2006 ◽

Vol 85 (10) ◽

pp. 900-904 ◽

Cited By ~ 56

Author(s):

C.-K. Park ◽

H.Y. Li ◽

K.-Y. Yeon ◽

S.J. Jung ◽

S.-Y. Choi ◽

...

Keyword(s):

Molecular Mechanisms ◽

Transient Receptor Potential ◽

Receptor Potential ◽

Inhibitory Effect ◽

Transient Receptor Potential Vanilloid ◽

Afferent Neurons ◽

Patch Clamp Technique ◽

Independent Manner ◽

Pre Treatment ◽

Transient Receptor

Although eugenol is widely used in dentistry, little is known about the molecular mechanisms responsible for its anesthetic properties. In addition to calcium channels, recently demonstrated by our group, there could be another molecular target for eugenol. Using a whole-cell patch-clamp technique, we investigated the effect of eugenol on voltage-gated sodium channel currents ( I Na) in rat dental primary afferent neurons identified by retrograde labeling with a fluorescent dye in maxillary molars. Eugenol inhibited action potentials and I Na in both capsaicin-sensitive and capsaicin-insensitive neurons. The pre-treatment with capsazepine, a competitive antagonist of transient receptor potential vanilloid 1 (TRPV1), failed to block the inhibitory effect of eugenol on I Na, suggesting no involvement of TRPV1. Two types of I Na, tetrodotoxin (TTX)-resistant and TTX-sensitive I Na, were inhibited by eugenol. Our results demonstrated that eugenol inhibits I Na in a TRPV1-independent manner. We suggest that I Na inhibition by eugenol contributes to its analgesic effect.

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5-Iodoresiniferatoxin Evokes Hypothermia in Mice and Is a Partial Transient Receptor Potential Vanilloid 1 Agonist in Vitro

Journal of Pharmacology and Experimental Therapeutics ◽

10.1124/jpet.105.084277 ◽

2005 ◽

Vol 314 (3) ◽

pp. 1378-1385 ◽

Cited By ~ 47

Author(s):

Isao Shimizu ◽

Tohko Iida ◽

Nobuhiko Horiuchi ◽

Michael J. Caterina

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Transient Receptor

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Antinociceptive Effects of Emodin on CFA-Induced Inflammatory Pain in Rats

Natural Product Communications ◽

10.1177/1934578x20942002 ◽

2020 ◽

Vol 15 (7) ◽

pp. 1934578X2094200

Author(s):

Wan Ni ◽

Nianyun Wang ◽

Shenglan Tian ◽

Qingbang Xu

Keyword(s):

Mrna Expression ◽

Inflammatory Pain ◽

Transient Receptor Potential ◽

Interleukin 1 ◽

Receptor Potential ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Transient Receptor Potential Vanilloid ◽

Tnf Α ◽

Transient Receptor

The effect of emodin on complete Freund’s adjuvant (CFA)-induced inflammatory pain in rats and its potential molecular mechanism was investigated. For this, a rat model of inflammatory pain induced by CFA was established and rats were treated with emodin by intraperitoneal injection. The pain threshold was evaluated by the von Frey, thermo hyperalgesia, and cold plate tests. The mRNA expression of transient receptor potential channel ankyrin type-1 ( Trpa1) and transient receptor potential vanilloid 1 ( Trpv1) was detected by quantitative reverse transcription polymerase chain reaction, and the level of inflammatory cytokines was determined by enzyme-linked immunosorbent assay. The mechanical and thermal pain thresholds of CFA-treated rats were significantly lower than those of the control rats, while the paw withdrawal responses in response to cold stimulation were higher than that of the control group. Emodin treatment significantly improved CFA-induced hyperalgesia. Further results showed that emodin inhibits the upregulation of Trpa1 and Trpv1 mRNA expression in the dorsal root ganglion (DRG) of rats with inflammatory pain compared with the control group. Emodin also significantly reduced the levels of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6) in the serum of rats with inflammatory pain. Thus, emodin may inhibit hyperalgesia induced by inflammatory stimulation by downregulating the mRNA expression of Trpa1 and Trpv1 in DRG neurons and reducing the levels of TNF-α, IL-1β, and IL-6.

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Tachykinin (NK1, NK2 and NK3) receptor, transient receptor potential vanilloid 1 (TRPV1) and early transcription factor, cFOS, mRNA expression in rat tissues following systemic capsaicin treatment

Regulatory Peptides ◽

10.1016/j.regpep.2013.03.001 ◽

2013 ◽

Vol 183 ◽

pp. 35-41 ◽

Cited By ~ 5

Author(s):

Dale A. Kunde ◽

Amanda Crawford ◽

Dominic P. Geraghty

Keyword(s):

Transcription Factor ◽

Mrna Expression ◽

Transient Receptor Potential ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Rat Tissues ◽

Nk3 Receptor ◽

Early Transcription ◽

Transient Receptor

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Synthetic Fluororutaecarpine Inhibits Inflammatory Stimuli and Activates Endothelial Transient Receptor Potential Vanilloid-Type 1

Molecules ◽

10.3390/molecules22040656 ◽

2017 ◽

Vol 22 (4) ◽

pp. 656 ◽

Cited By ~ 3

Author(s):

Chi-Ming Lee ◽

Jiun-An Gu ◽

Tin-Gan Rau ◽

Chi Wang ◽

Chiao-Han Yen ◽

...

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Inflammatory Stimuli ◽

Transient Receptor

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Blockade of Transient Receptor Potential Vanilloid 4 Enhances Antioxidation after Myocardial Ischemia/Reperfusion

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/7283683 ◽

2019 ◽

Vol 2019 ◽

pp. 1-17 ◽

Cited By ~ 4

Author(s):

Qiongfeng Wu ◽

Kai Lu ◽

Zhaoyang Zhao ◽

Binbin Wang ◽

Huixia Liu ◽

...

Keyword(s):

Myocardial Ischemia ◽

Transient Receptor Potential ◽

Ischemia Reperfusion ◽

Receptor Potential ◽

Nuclear Accumulation ◽

Transient Receptor Potential Vanilloid ◽

Antioxidative Stress ◽

Transient Receptor ◽

Myocardial Ischemia Reperfusion

Antioxidative stress provides a cardioprotective effect during myocardial ischemia/reperfusion (I/R). Previous research has demonstrated that the blockade of transient receptor potential vanilloid 4 (TRPV4) attenuates myocardial I/R injury. However, the underlying mechanism remains unclear. The current study is aimed at investigating the antioxidative activity of TRPV4 inhibition and elucidating the underlying mechanisms in vitro and ex vivo. We found that the inhibiting TRPV4 by the selective TRPV4 blocker HC-067047 or specific TRPV4-siRNA significantly reduces reactive oxygen species (ROS) and methane dicarboxylic aldehyde (MDA) levels in H9C2 cells exposed to hypoxia/reoxygenation (H/R). Meanwhile, the activity of antioxidative enzymes, particularly superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), is enhanced. Furthermore, after H/R, HC-067047 treatment increases the expression of P-Akt and the translocation of nuclear factor E2-related factor 2 (Nrf2) and related antioxidant response element (ARE) mainly including SOD, GSH-Px, and catalase (CAT). LY294002, an Akt inhibitor, suppresses HC-067047 and specific TRPV4-siRNA-induced Nrf2 expression and its nuclear accumulation. Nrf2 siRNA attenuates HC-067047 and specific TRPV4-siRNA-induced ARE expression. In addition, treatment with LY294002 or Nrf2 siRNA significantly attenuates the antioxidant and anti-injury effects of HC-067047 in vitro. Finally, in experiments on isolated rat hearts, we confirmed the antioxidative stress roles of TRPV4 inhibition during myocardial I/R and the application of exogenous H2O2. In conclusion, the inhibition of TRPV4 exerts cardioprotective effects through enhancing antioxidative enzyme activity and expressions via the Akt/Nrf2/ARE pathway.

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