scholarly journals Permeation and block of TRPV1 channels by the cationic lidocaine derivative QX-314

2013 ◽  
Vol 109 (7) ◽  
pp. 1704-1712 ◽  
Author(s):  
Michelino Puopolo ◽  
Alexander M. Binshtok ◽  
Gui-Lan Yao ◽  
Seog Bae Oh ◽  
Clifford J. Woolf ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Neuronal Cell ◽  
Reversal Potential ◽  
Dorsal Root Ganglion Neurons ◽  
C6 Glioma Cells ◽  
Transient Receptor Potential Vanilloid ◽  
Trpv1 Channels ◽  
Inward Currents ◽  
Pore Dilation ◽  
Ganglion Neurons

QX-314 ( N-ethyl-lidocaine) is a cationic lidocaine derivative that blocks voltage-dependent sodium channels when applied internally to axons or neuronal cell bodies. Coapplication of external QX-314 with the transient receptor potential vanilloid 1 protein (TRPV1) agonist capsaicin produces long-lasting sodium channel inhibition in TRPV1-expressing neurons, suggestive of QX-314 entry into the neurons. We asked whether QX-314 entry occurs directly through TRPV1 channels or through a different pathway (e.g., pannexin channels) activated downstream of TRPV1 and whether QX-314 entry requires the phenomenon of “pore dilation” previously reported for TRPV1. With external solutions containing 10 or 20 mM QX-314 as the only cation, inward currents were activated by stimulation of both heterologously expressed and native TRPV1 channels in rat dorsal root ganglion neurons. QX-314-mediated inward current did not require pore dilation, as it activated within several seconds and in parallel with Cs-mediated outward current, with a reversal potential consistent with PQX-314/ PCs = 0.12. QX-314-mediated current was no different when TRPV1 channels were expressed in C6 glioma cells, which lack expression of pannexin channels. Rapid addition of QX-314 to physiological external solutions produced instant partial inhibition of inward currents carried by sodium ions, suggesting that QX-314 is a permeant blocker. Maintained coapplication of QX-314 with capsaicin produced slowly developing reduction of outward currents carried by internal Cs, consistent with intracellular accumulation of QX-314 to concentrations of 50–100 μM. We conclude that QX-314 is directly permeant in the “standard” pore formed by TRPV1 channels and does not require either pore dilation or activation of additional downstream channels for entry.

scholarly journals Long-Term Diabetic Microenvironment Augments the Decay Rate of Capsaicin-Induced Currents in Mouse Dorsal Root Ganglion Neurons

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 775
Author(s):  
Xingjuan Chen ◽  
Yaqian Duan ◽  
Ashley Riley ◽  
Megan Welch ◽  
Fletcher White ◽  
...  
Keyword(s):  
Peripheral Neuropathy ◽  
Dorsal Root Ganglion ◽  
Patch Clamp ◽  
Dorsal Root ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Dorsal Root Ganglion Neurons ◽  
Transient Receptor Potential Vanilloid ◽  
Drg Neurons ◽  
Ganglion Neurons

Individuals with end-stage diabetic peripheral neuropathy present with decreased pain sensation. Transient receptor potential vanilloid type 1 (TRPV1) is implicated in pain signaling and resides on sensory dorsal root ganglion (DRG) neurons. We investigated the expression and functional activity of TRPV1 in DRG neurons of the Ins2+/Akita mouse at 9 months of diabetes using immunohistochemistry, live single cell calcium imaging, and whole-cell patch-clamp electrophysiology. 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence assay was used to determine the level of Reactive Oxygen Species (ROS) in DRGs. Although TRPV1 expressing neuron percentage was increased in Ins2+/Akita DRGs at 9 months of diabetes compared to control, capsaicin-induced Ca2+ influx was smaller in isolated Ins2+/Akita DRG neurons, indicating impaired TRPV1 function. Consistently, capsaicin-induced Ca2+ influx was decreased in control DRG neurons cultured in the presence of 25 mM glucose for seven days versus those cultured with 5.5 mM glucose. The high glucose environment increased cytoplasmic ROS accumulation in cultured DRG neurons. Patch-clamp recordings revealed that capsaicin-activated currents decayed faster in isolated Ins2+/Akita DRG neurons as compared to those in control neurons. We propose that in poorly controlled diabetes, the accelerated rate of capsaicin-sensitive TRPV1 current decay in DRG neurons decreases overall TRPV1 activity and contributes to peripheral neuropathy.

Do distinct populations of dorsal root ganglion neurons account for the sensory peptidergic innervation of the kidney?

2009 ◽  
Vol 297 (5) ◽  
pp. F1427-F1434 ◽  
Author(s):  
Tilmann Ditting ◽  
Gisa Tiegs ◽  
Kristina Rodionova ◽  
Peter W. Reeh ◽  
Winfried Neuhuber ◽  
...  
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Current Injection ◽  
Dorsal Root Ganglion Neurons ◽  
Transient Receptor Potential Vanilloid ◽  
Drg Neurons ◽  
Acid Sensitivity ◽  
Trpv1 Channels ◽  
Induced Currents ◽  
Ganglion Neurons

Peptidergic afferent renal nerves (PARN) have been linked to kidney damage in hypertension and nephritis. Neither the receptors nor the signals controlling local release of neurokinines [calcitonin gene-related peptide (CGRP) and substance P (SP)] and signal transmission to the brain are well-understood. We tested the hypothesis that PARN, compared with nonrenal afferents (Non-RN), are more sensitive to acidic stimulation via transient receptor potential vanilloid type 1 (TRPV1) channels and exhibit a distinctive firing pattern. PARN were distinguished from Non-RN by fluorescent labeling (DiI) and studied by in vitro patch-clamp techniques in dorsal root ganglion neurons (DRG; T11-L2). Acid-induced currents or firing due to current injection or acidic superfusion were studied in 252 neurons, harvested from 12 Sprague-Dawley rats. PARN showed higher acid-induced currents than Non-RN (transient: 15.9 ± 5.1 vs. 0.4 ± 0.2* pA/pF at pH 6; sustained: 20.0 ± 4.5 vs. 6.2 ± 1.2* pA/pF at pH 5; * P < 0.05). The TRPV1 antagonist capsazepine inhibited sustained, amiloride-transient currents. Forty-eight percent of PARN were classified as tonic neurons (TN = sustained firing during current injection), and 52% were phasic (PN = transient firing). Non-RN were rarely tonic (15%), but more frequently phasic (85%), than PARN ( P < 0.001). TN were more frequently acid-sensitive than PN (50–70 vs. 2–20%, P < 0.01). Furthermore, renal PN were more frequently acid-sensitive than nonrenal PN (20 vs. 2%, P < 0.01). Confocal microscopy revealed innervation of renal vessels, tubules, and glomeruli by CGRP- and partly SP-positive fibers coexpressing TRPV1. Our data show that PARN are represented by a very distinct population of small-to-medium sized DRG neurons exhibiting more frequently tonic firing and TRPV1-mediated acid sensitivity. These very distinct DRG neurons might play a pivotal role in renal physiology and disease.

scholarly journals Spinal PAR2 Activation Contributes to Hypersensitivity Induced by Peripheral Inflammation in Rats

2021 ◽  
Vol 22 (3) ◽  
pp. 991
Author(s):  
Petra Mrozkova ◽  
Diana Spicarova ◽  
Jiri Palecek
Keyword(s):  
Synaptic Transmission ◽  
Dorsal Horn ◽  
Dorsal Root ◽  
Transient Receptor Potential ◽  
Thermal Hyperalgesia ◽  
Dorsal Root Ganglion Neurons ◽  
Peripheral Inflammation ◽  
Transient Receptor Potential Vanilloid ◽  
Behavioral Experiments ◽  
Ganglion Neurons

The mechanisms of inflammatory pain need to be identified in order to find new superior treatments. Protease-activated receptors 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) are highly co-expressed in dorsal root ganglion neurons and implicated in pain development. Here, we examined the role of spinal PAR2 in hyperalgesia and the modulation of synaptic transmission in carrageenan-induced peripheral inflammation, using intrathecal (i.t.) treatment in the behavioral experiments and recordings of spontaneous, miniature and dorsal root stimulation-evoked excitatory postsynaptic currents (sEPSCs, mEPSCs and eEPSCs) in spinal cord slices. Intrathecal PAR2-activating peptide (AP) administration aggravated the carrageenan-induced thermal hyperalgesia, and this was prevented by a TRPV1 antagonist (SB 366791) and staurosporine i.t. pretreatment. Additionally, the frequency of the mEPSC and sEPSC and the amplitude of the eEPSC recorded from the superficial dorsal horn neurons were enhanced after acute PAR2 AP application, while prevented with SB 366791 or staurosporine pretreatment. PAR2 antagonist application reduced the thermal hyperalgesia and decreased the frequency of mEPSC and sEPSC and the amplitude of eEPSC. Our findings highlight the contribution of spinal PAR2 activation to carrageenan-induced hyperalgesia and the importance of dorsal horn PAR2 and TRPV1 receptor interactions in the modulation of nociceptive synaptic transmission.

scholarly journals Calcium transient evoked by TRPV1 activators is enhanced by tumor necrosis factor-α in rat pulmonary sensory neurons

2010 ◽  
Vol 299 (4) ◽  
pp. L483-L492 ◽  
Author(s):  
Youmin Hu ◽  
Qihai Gu ◽  
Ruei-Lung Lin ◽  
Richard Kryscio ◽  
Lu-Yuan Lee
Keyword(s):  
Sensory Neurons ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Allyl Isothiocyanate ◽  
Calcium Transient ◽  
Somatic Tissue ◽  
Dorsal Root Ganglion Neurons ◽  
Prolonged Treatment ◽  
Transient Receptor Potential Vanilloid ◽  
Ganglion Neurons

TNFα, a proinflammatory cytokine known to be involved in the pathogenesis of allergic asthma, has been shown to induce hyperalgesia in somatic tissue via a sensitizing effect on dorsal root ganglion neurons expressing transient receptor potential vanilloid type 1 receptor (TRPV1). Because TRPV1-expressing pulmonary sensory neurons play an important role in regulating airway function, this study was carried out to determine whether TNFα alters the sensitivity of these neurons to chemical activators. Responses of isolated nodose and jugular ganglion neurons innervating the rat lungs were determined by measuring the transient increase in intracellular Ca2+ concentration ([Ca2+]i). Our results showed the following. 1) A pretreatment with TNFα (50 ng/ml) for ∼24 h increased significantly the peak Δ[Ca2+]i evoked by capsaicin (Cap) in these neurons. A pretreatment with the same concentration of TNFα for a longer duration (∼48 h) did not further increase the response, but pretreatment for a shorter duration (1 h) or with a lower concentration (25 ng/ml, 24 h) failed to enhance the Cap sensitivity. 2) The same TNFα pretreatment also induced similar but less pronounced and less uniform increases in the responses to acid (pH 6.5–5.5), 2-aminoethoxydiphenyl borate (2-APB), a common activator of TRPV1, V2, and V3 channels, and allyl isothiocyanate (AITC), a selective activator of TRPA1 channel. 3) In sharp contrast, the responses to ATP, ACh, and KCl were not affected by TNFα. 4) The TNFα-induced hypersensitivity to Cap was not prevented by pretreatment with indomethacin (30 μM). 5) The immunoreactivity to both TNF receptor types 1 and 2 were detected in rat vagal pulmonary sensory neurons. In conclusion, prolonged treatment with TNFα induces a pronounced potentiating effect on the responses of isolated pulmonary sensory neurons to TRPV1 activators. This action of TNFα may contribute in part to the airway hyperresponsiveness induced by this cytokine.

scholarly journals The role of spinal cord vanilloid (TRPV1) receptors in pain modulation

2008 ◽  
pp. S69-S77
Author(s):  
D Špicarová ◽  
J Paleček
Keyword(s):  
Spinal Cord ◽  
Transient Receptor Potential ◽  
Pain Modulation ◽  
Dorsal Root Ganglion Neurons ◽  
Spinal Cord Dorsal Horn ◽  
Transient Receptor Potential Vanilloid ◽  
Peripheral Tissues ◽  
Trpv1 Receptors ◽  
Ganglion Neurons

Transient receptor potential vanilloid 1 (TRPV1) receptor is a nonselective cation channel activated by capsaicin, a pungent substance from chili peppers. It is considered to act as an integrator of various physical and chemical nociceptive stimuli, as it can be gated by noxious heat (>43 oC), low pH (protons) and also by recently described endogenous lipids. The structure and function of TRPV1 receptors was vigorously studied, especially since its cloning in 1997. However, most of the research was pointed towards the role of TRPV1 receptors in the peripheral tissues. Mounting evidence now suggests that TRPV1 receptors on the central branches of dorsal root ganglion neurons in the spinal cord may play an important role in modulation of pain and nociceptive transmission. The aim of this short review was to summarize the knowledge about TRPV1 receptors in the spinal cord dorsal horn, preferentially from morphological and electrophysiological studies on spinal cord slices and from in vivo experiments.

CDK5 inhibits the clathrin-dependent internalization of TRPV1 by phosphorylating the clathrin adaptor protein AP2μ2

2019 ◽  
Vol 12 (585) ◽  
pp. eaaw2040 ◽  
Author(s):  
Jiao Liu ◽  
Junxia Du ◽  
Yun Wang
Keyword(s):  
Drug Targets ◽  
Transient Receptor Potential ◽  
Phosphorylation Site ◽  
Thermal Hyperalgesia ◽  
Adaptor Protein ◽  
Receptor Potential ◽  
Dorsal Root Ganglion Neurons ◽  
Transient Receptor Potential Vanilloid ◽  
Transient Receptor ◽  
Ganglion Neurons

Transient receptor potential vanilloid 1 (TRPV1), a nonselective, ligand-gated cation channel, responds to multiple noxious stimuli and is targeted by many kinases that influence its trafficking and activity. Studies on the internalization of TRPV1 have mainly focused on that induced by capsaicin or other agonists. Here, we report that constitutive internalization of TRPV1 occurred in a manner dependent on clathrin, dynamin, and adaptor protein complex 2 (AP2). The μ2 subunit of AP2 (AP2μ2) interacted directly with TRPV1 and was required for its constitutive internalization. Cyclin-dependent kinase 5 (CDK5) phosphorylated AP2μ2 at Ser45, which reduced the interaction between TRPV1 and AP2μ2, leading to decreased TRPV1 internalization. Intrathecal delivery of a cell-penetrating fusion peptide corresponding to the Cdk5 phosphorylation site in AP2μ2, which competed with AP2μ2 for phosphorylation by Cdk5, increased the abundance of TRPV1 on the surface of dorsal root ganglion neurons and reduced complete Freund’s adjuvant (CFA)–induced inflammatory thermal hyperalgesia in rats. In addition to describing a mechanism of TRPV1 constitutive internalization and its inhibition by CDK5, these findings demonstrate that CDK5 promotes inflammatory thermal hyperalgesia by reducing TRPV1 internalization, providing previously unidentified insights into the search for drug targets to treat pain.

scholarly journals Attenuation of TRPV1 and TRPV4 Expression and Function in Mouse Inflammatory Pain Models Using Electroacupuncture

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Wei-Hsin Chen ◽  
Jason T. C. Tzen ◽  
Ching Liang Hsieh ◽  
Yung Hsiang Chen ◽  
Tzu-Jou Lin ◽  
...  
Keyword(s):  
Inflammatory Pain ◽  
Transient Receptor Potential ◽  
Thermal Hyperalgesia ◽  
Receptor Potential ◽  
Dorsal Root Ganglion Neurons ◽  
Transient Receptor Potential Vanilloid ◽  
Pain Mechanisms ◽  
Electrophysiological Properties ◽  
Pain Models ◽  
Ganglion Neurons

Although pain is a major human affliction, our understanding of pain mechanisms is limited. TRPV1 (transient receptor potential vanilloid subtype 1) and TRPV4 are two crucial receptors involved in inflammatory pain, but their roles in EA- (electroacupuncture-) mediated analgesia are unknown. We injected mice with carrageenan (carra) or a complete Freund’s adjuvant (CFA) to model inflammatory pain and investigated the analgesic effect of EA using animal behavior tests, immunostaining, Western blotting, and a whole-cell recording technique. The inflammatory pain model mice developed both mechanical and thermal hyperalgesia. Notably, EA at the ST36 acupoint reversed these phenomena, indicating its curative effect in inflammatory pain. The protein levels of TRPV1 and TRPV4 in DRG (dorsal root ganglion) neurons were both increased at day 4 after the initiation of inflammatory pain and were attenuated by EA, as demonstrated by immunostaining and Western blot analysis. We verified DRG electrophysiological properties to confirm that EA ameliorated peripheral nerve hyperexcitation. Our results indicated that the AP (action potential) threshold, rise time, and fall time, and the percentage and amplitude of TRPV1 and TRPV4 were altered by EA, indicating that EA has an antinociceptive role in inflammatory pain. Our results demonstrate a novel role for EA in regulating TRPV1 and TRPV4 protein expression and nerve excitation in mouse inflammatory pain models.

scholarly journals Systemic QX-314 Reduces Bone Cancer Pain through Selective Inhibition of Transient Receptor Potential Vanilloid Subfamily 1–expressing Primary Afferents in Mice

2016 ◽  
Vol 125 (1) ◽  
pp. 204-218 ◽  
Author(s):  
Satoshi Fuseya ◽  
Katsumi Yamamoto ◽  
Hitoshi Minemura ◽  
Satoshi Yamaori ◽  
Tomoyuki Kawamata ◽  
...  
Keyword(s):  
Cancer Pain ◽  
Transient Receptor Potential ◽  
Bone Cancer ◽  
Receptor Potential ◽  
Adenosine Monophosphate ◽  
Selective Inhibition ◽  
Dorsal Root Ganglion Neurons ◽  
Bone Cancer Pain ◽  
Transient Receptor Potential Vanilloid ◽  
Ganglion Neurons

Abstract Background The aim of this study was to determine whether systemic administration of QX-314 reduces bone cancer pain through selective inhibition of transient receptor potential vanilloid subfamily 1 (TRPV1)–expressing afferents. Methods A mouse model of bone cancer pain was used. The authors examined the effects of bolus (0.01 to 3 mg/kg, n = 6 to 10) and continuous (5 mg kg−1 h−1, n = 5) administration of QX-314 on both bone cancer pain–related behaviors and phosphorylated cyclic adenosine monophosphate response element–binding protein expression in dorsal root ganglion neurons (n = 3 or 6) and the effects of ablation of TRPV1-expressing afferents on bone cancer pain–related behaviors (n = 10). Results The numbers of flinches indicative of ongoing pain in QX-314–treated mice were smaller than those in vehicle-treated mice at 10 min (3 mg/kg, 4 ± 3; 1 mg/kg, 5 ± 3 vs. 12 ± 3; P &lt; 0.001; n = 8 to 9), 24 h (3 ± 2 vs. 13 ± 3, P &lt; 0.001), and 48 h (4 ± 1 vs. 12 ± 2, P &lt; 0.001; n = 5 in each group) after QX-314 administration, but impaired limb use, weight-bearing including that examined by the CatWalk system, and rotarod performance indicative of movement-evoked pain were comparable. QX-314 selectively inhibited the increase in phosphorylated cyclic adenosine monophosphate response element–binding protein expression in TRPV1-positive, but not in TRPV1-negative, dorsal root ganglion neurons compared to that in the case of vehicle administration (32.2 ± 3.0% vs. 52.6 ± 5.9%, P &lt; 0.001; n = 6 in each group). Ablation of TRPV1-expressing afferents mimicked the effects of QX-314. Conclusion This study showed that systemic administration of QX-314 in mice inhibits some behavioral aspects of bone cancer pain through selective inhibition of TRPV1-expressing afferents without coadministration of TRPV1 agonists.

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