• International Journal of Oral Biology
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• v.46 no.3
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• pp.119-126
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• 2021

Activation of transient receptor potential vanilloid 1 (TRPV1), a calcium permeable channel expressed in primary sensory neurons, induces the release of glutamate from their central and peripheral afferents during normal acute and pathological pain. However, little information is available regarding the glutamate release mechanism associated with TRPV1 activation in primary sensory neurons. To address this issue, we investigated the expression of vesicular glutamate transporter (VGLUT) in TRPV1-immunopositive (+) neurons in the rat trigeminal ganglion (TG) under normal and complete Freund's adjuvant (CFA)-induced inflammatory pain conditions using behavioral testing as well as double immunofluorescence staining with antisera against TRPV1 and VGLUT1 or VGLUT2. TRPV1 was primarily expressed in small and medium-sized TG neurons. TRPV1+ neurons constituted approximately 27% of all TG neurons. Among all TRPV1+ neurons, the proportion of TRPV1+ neurons coexpressing VGLUT1 (VGLUT1+/TRPV1+ neurons) and VGLUT2 (VGLUT2+/TRPV1+ neurons) was 0.4% ± 0.2% and 22.4% ± 2.8%, respectively. The proportion of TRPV1+ and VGLUT2+ neurons was higher in the CFA group than in the control group (TRPV1+ neurons: 31.5% ± 2.5% vs. 26.5% ± 1.2%, VGLUT2+ neurons: 31.8% ± 1.1% vs. 24.6% ± 1.5%, p < 0.05), whereas the proportion of VGLUT1+, VGLUT1+/TRPV1+, and VGLUT2+/TRPV1+ neurons did not differ significantly between the CFA and control groups. These findings together suggest that VGLUT2, a major isoform of VGLUTs, is involved in TRPV1 activation-associated glutamate release during normal acute and inflammatory pain.

• The Korean Journal of Pain
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• v.37 no.2
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• pp.151-163
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• 2024

Background: Galangin, commonly employed in traditional Chinese medicine for its diverse medicinal properties, exhibits potential in treating inflammatory pain. Nevertheless, its mechanism of action remains unclear. Methods: Mice were randomly divided into 4 groups for 7 days: a normal control group, a galangin-treated (25 and 50 mg/kg), and a positive control celecoxib (20 mg/kg). Analgesic and anti-inflammatory effects were evaluated using a hot plate test, acetic acid-induced writhing test, acetic acid-induced vascular permeability test, formalin-induced paw licking test, and carrageenan-induced paw swelling test. The interplay between galangin, transient receptor potential vanilloid 1 (TRPV1), NF-κB, COX-2, and TNF-α proteins was evaluated via molecular docking. COX-2, PGE2, IL-1β, IL-6, and TNF-α levels in serum were measured using ELISA after capsaicin administration (200 nmol/L). TRPV1 expression in the dorsal root ganglion was analyzed by Western blot. The quantities of substance P (SP) and calcitonin gene-related peptide (CGRP) were assessed using qPCR. Results: Galangin reduced hot plate-induced licking latency, acetic acid-induced contortions, carrageenan-triggered foot inflammation, and capillary permeability in mice. It exhibited favorable affinity towards TRPV1, NF-κB, COX-2, and TNF-α, resulting in decreased levels of COX-2, PGE2, IL-1β, IL-6, and TNF-α in serum following capsaicin stimulation. Galangin effectively suppressed the upregulation of TRPV1 protein and associated receptor neuropeptides CGRP and SP mRNA, while concurrently inhibiting the expression of NF-κB, TNF-α, COX-2, and PGE2 mRNA. Conclusions: Galangin exerts its anti-inflammatory pain effects by inhibiting TRPV1 activation and regulating COX-2, NF-κB/TNF-α expression, providing evidence for the use of galangin in the management of inflammatory pain.

• The Korean Journal of Pain
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• v.34 no.3
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• pp.262-270
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• 2021

Background: Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel implicated in pain sensation in response to heat, protons, and capsaicin (CAPS). It is well established that TRPV1 is involved in mechanical allodynia. This study investigates the effect of Ononis spinosa (Fabaceae) in CAPS-induced mechanical allodynia and its mechanism of action. Methods: Mechanical allodynia was induced by the intraplantar (ipl) injection of 40 ㎍ CAPS into the left hind paw of male Wistar rats. Animals received an ipl injection of 100 ㎍ O. spinosa methanolic leaf extract or 2.5% diclofenac sodium 20 minutes before CAPS injection. Paw withdrawal threshold (PWT) was measured using von Frey filament 30, 90, and 150 minutes after CAPS injection. A molecular docking tool, AutoDock 4.2, was used to study the binding energies and intermolecular interactions between O. spinosa constituents and TRPV1 receptor. Results: The ipsilateral ipl injection of O. spinosa before CAPS injection increased PWT in rats at all time points. O. spinosa decreased mechanical allodynia by 5.35-fold compared to a 3.59-fold decrease produced by diclofenac sodium. The ipsilateral pretreatment with TRPV1 antagonist (300 ㎍ 4-[3-Chloro-2-pyridinyl]-N-[4-[1,1-dimethylethyl] phenyl]-1-piperazinecarboxamide [BCTC]) as well as the β2-adrenoreceptor antagonist (150 ㎍ butoxamine) attenuated the action of O. spinosa. Depending on molecular docking results, the activity of the extract could be attributed to the bindings of campesterol, stigmasterol, and ononin compounds to TRPV1. Conclusions: O. spinosa alleviated CAPS-induced mechanical allodynia through 2 mechanisms: the direct modulation of TRPV1 and the involvement of β2 adrenoreceptor signaling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.312-317
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• 2011

Vanilloid receptor TRPV1 (known as capsaicin channel, transient receptor potential vanilloid 1) is known to be a key protein in the pain signal transduction. However, the proteins controlling the activity of the channel are not much known yet. Recently mouse Rab11-FIP3 (Rab11-family interaction protein 3) was found and reported to interact with rat TRPV1. Rab11 has been shown to play a key role in a variety of cellular processes including plasma membrane recycling, phagocytosis, and transport of secretory proteins from the trans-Golgi network. Therefore, Rab11-FIP3 was proposed to be involved in the membrane trafficking of TRPV1. In this study, the unreported rat Rab11-FIP3 was yet cloned in order to show the specific interaction of the TRPV1 and Rab11-FIP3 in the same species of rat and to examine the membrane trafficking of TRPV1. The result showed that rat Rab11-FIP3 is expected to have 489 amino acids and showed 80% identity with that of human and over 90% identity with that of mouse. Rab11-FIP3 was found to be expressed in heart, brain, kidney, testis using northern and western blot analyses. We also found that rat Rab11-FIP3 was colocalized with rat TRPV1 but not with TRPV2 of same family in the rat brain by using immunohistochemistry showing that two proteins interact specifically, suggesting the role of Rab11-FIP3 in the membrane trafficking.

• CELLMED
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• v.4 no.2
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• pp.12.1-12.12
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• 2014

Epinephrine is a critical drug for patients at risk for anaphylaxis. Here, we suggest moxibustion as an alternative method to reduce anaphylaxis. Moxibustion was applied to the Shimen (CV5) acupoint and found to attenuate compound 48/80-induced mortality. Capsazepine, a transient receptor potential vanilloid (TRPV) 1 antagonist, significantly improved overall survival rates compared to groups treated with moxibustion or 2-aminoethoxydiphenyl borate (an activator of TRPV1, 2, and 3). Probenecid (a TRPV2 agonist) also increased survival rate and reduced histamine levels. Survival rates increased by moxibustion and probenecid were completely inhibited by ruthenium red (a TRPV2 and 3 antagonist) and gadolinium chloride (general TRPV antagonist), respectively. Passive cutaneous anaphylaxis and ear swelling were significantly reduced by moxibustion and probenecid (p < 0.05). In cardiomyocytes, TRPV2 was over-expressed by compound 48/80 and histamine but this increased TRPV2 expression decreased to baseline with moxibustion and probenecid treatment. In addition, intracellular calcium levels increased by compound 48/80 were reduced by probenecid. Overall, these findings suggest that the reduction of anaphylaxis caused by moxibustion could represent a new mechanism of moxibustion related to the regulation of TRPV2 activation and promotion of epinephrine secretion.

• Journal of Animal Science and Technology
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• v.56 no.8
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• pp.33.1-33.8
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• 2014

Background: Sox 9 is a major marker of chondrocyte differentiation. When chondrocytes are cultured in vitro they progressively de-differentiate and this is associated with a decline in Sox 9 expression. The active form of vitamin D, 1, 25 $(OH)_2D_3$ has been shown to be protective of cartilage in both humans and animals. In this study equine articular chondrocytes were grown in culture and the effects of 1, 25 $(OH)_2D_3$ upon Sox 9 expression examined. The expression of the transient receptor potential vanilloid (TRPV) ion channels 5 and 6 in equine chondrocytes in vitro, we have previously shown, is inversely correlated with de-differentiation. The expression of these channels in response to 1, 25 $(OH)_2D_3$ administration was therefore also examined. Results: The active form of vitamin D (1, 25 $(OH)_2D_3$ when administered to cultured equine chondrocytes at two different concentrations significantly increased the expression of Sox 9 at both. In contrast 1, 25 $(OH)_2D_3$ had no significant effect upon the expression of either TRPV 5 or 6 at either the protein or the mRNA level. Conclusions: The increased expression of Sox 9, in equine articular chondrocytes in vitro, in response to the active form of vitamin D suggests that this compound could be utilized to inhibit the progressive de-differentiation that is normally observed in these cells. It is also supportive of previous studies indicating that $1{\alpha}$, 25-dihydroxyvitamin $D_3$ can have a protective effect upon cartilage in animals in vivo. The previously observed correlation between the degree of differentiation and the expression levels of TRPV 5/6 had suggested that these ion channels may have a direct involvement in, or be modulated by, the differentiation process in vitro. The data in the present study do not support this.

• Journal of Korean Medicine for Obesity Research
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• v.18 no.2
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• pp.57-63
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• 2018

Objectives: Metabolic syndrome is defined by a cluster of major cardiovascular risk factors: obesity, insulin resistance, dyslipidemia, and arterial hypertension. Several members of a large family of nonselective cation entry channels, e.g., transient receptor potential vanilloid 4 (TRPV4) channels have been associated with the development of dyslipidemia and hypertension. The purpose of this study was to investigate the effects of Leejung-tang (Lizhong-tang), Rikkunshito, and Bojungikgi-tang (Buzhongyiqi-tang) on TRPV4 channel. Methods: Human embryonic kidney 293 cells stably transfected with the TRPV4 expression vectors were maintained in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, $5{\mu}g/mL$ blasticidin, and 0.4 mg/mL zeocin in a humidified 20% $O_2/10%$ $CO_2$ atmosphere at $37^{\circ}C$. Whole-cell patch clamp recordings were obtained using an Axopatch 700B amplifier and pClamp v.10.4 software (Molecular Devices, San Jose, CA, USA), and signals were digitalized at 5 kHz using Digidata 1422A. Results: Leejung-tang and Rikkunshito (10, 30 and 50 mg/mL) had no effects on the TRPV4 whole-cell currents at dose dependent manner. However, Bojungikgi-tang (10, 30, and 50 mg/mL) inhibited the TRPV4 whole-cell currents in a dose dependent manner and the half maximal inhibitory concentration (IC50) of Bojungikgi-tang was 18.2 mg/mL. Conclusions: These results suggest that Bojungikgi-tang plays an important roles to inhibit the TRPV4 channel, suggesting that Bojungikgi-tang is considered one of the candidate agents for the treatment of metabolic syndrome such as dyslipidemia and hypertension.

• Applied Microscopy
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• v.42 no.1
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• pp.27-33
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• 2012

Transient receptor potential ankyrin 1 (TRPA1), responding to noxious cold (${\leq}17^{\circ}C$) and pungent compounds, is implicated in nociception, but little is known about the coexpression of TRPA1 and other channels or receptors involved in the nociception in craniofacial regions. To address this issue, we characterized the TRPA1-immunopositive (+) neurons in the rat trigeminal ganglion (TG) and investigated their colocalization with other proteins known to be expressed in nociceptive neurons, such as transient receptor potential vanilloid (TRPV1) and $P2X_3$ receptor, using light microscopic immunofluorescence labeling method with TRPA1 and TRPV1 or $P2X_3$ antisera. The majority of TRPA1+ neurons costained for TRPV1 (TRPV1+/TRPA1+; 58.8%, 328/558) and 41.2% only expressed TRPA1 but not TRPV1. The TRPV1+/TRPA1+ neurons were small and medium sized. In addition, we investigated the colocalization of TRPA1 with $P2X_3$, a nonselective cation channel activated by ATP that may be released in the extracellular space as a result of tissue damage and inflammation. Among all TRPA1+ TG neurons, 26.1% (310/1186) costained for $P2X_3$, whereas 73.9% (876/1186) of TRPA1+ neurons did not coexpress $P2X_3$. $P2X_3$+/TRPA1+ neurons were predominantly small and medium sized. These results suggest that TRPA1+ neurons coexpressing TRPV1 or $P2X_3$ are involved in specific roles in the transmission and processing of orofacial nociceptive information by noxious cold, heat, and inflammation.

• Animal cells and systems
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• v.15 no.2
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• pp.95-106
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• 2011

The transient receptor potential vanilloid 4 (TRPV4) cation channel, a member of the TRP vanilloid subfamily, is expressed in a broad range of tissues. Nitric oxide (NO) as a gaseous signal mediator shows a variety of important biological effects. In many instances, NO has been shown to exhibit its activities via a protein S-nitrosylation mechanism in order to regulate its protein functions. With functional assays via site-directed mutagenesis, we demonstrate herein that NO induces the S-nitrosylation of TRPV4 $Ca^{2+}$ channel on the $Cys^{853}$ residue, and the S-nitrosylation of $Cys^{853}$ reduced its channel sensitivity to 4-${\alpha}$ phorbol 12,13-didecanoate and the interaction between TRPV4 and calmodulin. A patch clamp experiment and $Ca^{2+}$ image analysis show that the S-nitrosylation of $Cys^{853}$ modulates the TRPV4 channel as an inhibitor. Thus, our data suggest a novel regulatory mechanism of TRPV4 via NO-mediated S-nitrosylation on its $Cys^{853}$ residue.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.85-94
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• 2007

Vanilloid receptor I [transient receptor potential vanilloid subfamily member 1 (TRPV1), also known as VR1] is a non-selective cationic channel activated by noxious heat, vanilloids, and acid, thereby causing pain. VR1 possesses six transmembrane domain and N-and C-terminus cytosolic domains, and appears to be a homotetramer. We studied the structural properties of Cterminus of VR1 (VR1C) using CD and NMR spectroscopy. DPC micelles, with a zwitterionic surface, and SDS micelles, with a negatively charged surface, were used as a membrane mimetic model system. Both SDS and DPC micelles could increase the stability of helical structures and/or reduce the aggregation form of the VR1C. However, the structural changing mode of the VR1C induced by the SDS and DPC micelles was different. The changes according to the various pHs were also different in two micelles conditions. Because the net charges of the SDS and DPC micelles are negative and neutral, respectively, we anticipate that this difference might affect the structure of the VR1C by electrostatic interaction between the surface of the VR1C and phospholipids of the detergent micelles. Based on these similarity and dissimilarity of changing aspects of the VR1C, it is supposed that the VR1C probably has the real pI value near the pH 7. Generally, mild extracellular acidic pH ($6.5{\sim}6.8$) potentiates VRI channel activation by noxious heat and vanilloids, whereas acidic conditions directly activate the channel. The channel activation of the VRI might be related to the structural change of VR1C caused by pH (electrostatic interactions), especially near the pH 7. By measuring the $^1-^{15}N$ TROSY spectra of the VR1C, we could get more resolved and dispersed spectra at the low pH and/or detergent micelles conditions. We will try to do further NMR experiments in low pH with micelles conditions in order to get more information about the structure of VR1C.