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Sample records for capsaicin receptor trpv1

  1. Integrating TRPV1 Receptor Function with Capsaicin Psychophysics

    PubMed Central

    Smutzer, Gregory; Devassy, Roni K.

    2016-01-01

    Capsaicin is a naturally occurring vanilloid that causes a hot, pungent sensation in the human oral cavity. This trigeminal stimulus activates TRPV1 receptors and stimulates an influx of cations into sensory cells. TRPV1 receptors function as homotetramers that also respond to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Kinase-mediated phosphorylation of TRPV1 leads to increased sensitivity to both chemical and thermal stimuli. In contrast, desensitization occurs via a calcium-dependent mechanism that results in receptor dephosphorylation. Human psychophysical studies have shown that capsaicin is detected at nanomole amounts and causes desensitization in the oral cavity. Psychophysical studies further indicate that desensitization can be temporarily reversed in the oral cavity if stimulation with capsaicin is resumed at short interstimulus intervals. Pretreatment of lingual epithelium with capsaicin modulates the perception of several primary taste qualities. Also, sweet taste stimuli may decrease the intensity of capsaicin perception in the oral cavity. In addition, capsaicin perception and hedonic responses may be modified by diet. Psychophysical studies with capsaicin are consistent with recent findings that have identified TRPV1 channel modulation by phosphorylation and interactions with membrane inositol phospholipids. Future studies will further clarify the importance of capsaicin and its receptor in human health and nutrition. PMID:26884754

  2. The capsaicin receptor TRPV1 as a novel modulator of neural precursor cell proliferation.

    PubMed

    Stock, Kristin; Garthe, Alexander; de Almeida Sassi, Felipe; Glass, Rainer; Wolf, Susanne A; Kettenmann, Helmut

    2014-12-01

    The capsaicin receptor (TRPV1, transient receptor potential vanilloid type 1) was first discovered in the peripheral nervous system as a detector of noxious chemical and thermal stimuli including the irritant chili pepper. Recently, there has been increasing evidence of TRPV1 expression in the central nervous system. Here, we show that TRPV1 is expressed in neural precursor cells (NPCs) during postnatal development, but not in the adult. However, expression of TRPV1 is induced in the adult in paradigms linked to an increase in neurogenesis, such as spatial learning in the Morris water maze or voluntary exercise. Loss of TRPV1 expression in knockout mice leads to an increase in NPC proliferation. Functional TRPV1 expression has been confirmed in cultured NPCs. Our results indicate that TRPV1 expression influences both postnatal and activity-induced neurogenesis in adulthood. PMID:25092424

  3. Nicotinic Acid Activates the Capsaicin Receptor TRPV1 – A Potential Mechanism for Cutaneous Flushing

    PubMed Central

    Ma, Linlin; Lee, Bo Hyun; Mao, Rongrong; Cai, Anping; Jia, Yunfang; Clifton, Heather; Schaefer, Saul; Xu, Lin; Zheng, Jie

    2014-01-01

    Objective Nicotinic acid (a.k.a. niacin or vitamin B3), widely used to treat dyslipidemias, represents an effective and safe means to reduce the risk of mortality from cardiovascular disease. Nonetheless, a substantial fraction of patients discontinue treatment due to a strong side effect of cutaneous vasodilation, commonly termed flushing. In the present study we tested the hypothesis that nicotinic acid causes flushing partially by activating the capsaicin receptor TRPV1, a polymodal cellular sensor that mediates the flushing response upon consumption of spicy food. Approach and Results We observed that the nicotinic acid-induced increase in blood flow was substantially reduced in Trpv1−/− knockout mice, indicating involvement of the channel in flushing response. Using exogenously expressed TRPV1, we confirmed that nicotinic acid at sub-millimolar to millimolar concentrations directly and potently activates TRPV1 from the intracellular side. Binding of nicotinic acid to TRPV1 lowers its activation threshold for heat, causing channel opening at physiological temperatures. Activation of TRPV1 by voltage or ligands (capsaicin and 2-APB) is also potentiated by nicotinic acid. We further demonstrated that nicotinic acid does not compete directly with capsaicin but may activate TRPV1 through the 2-APB activation pathway. Using live-cell fluorescence imaging, we observed that nicotinic acid can quickly enter the cell through a transporter-mediated pathway to activate TRPV1. Conclusions Direct activation of TRPV1 by nicotinic acid may lead to cutaneous vasodilation that contributes to flushing, suggesting a potential novel pathway to inhibit flushing and improve compliance. PMID:24675661

  4. The capsaicin receptor TRPV1 is a crucial mediator of the noxious effects of mustard oil.

    PubMed

    Everaerts, Wouter; Gees, Maarten; Alpizar, Yeranddy A; Farre, Ricard; Leten, Cindy; Apetrei, Aurelia; Dewachter, Ilse; van Leuven, Fred; Vennekens, Rudi; De Ridder, Dirk; Nilius, Bernd; Voets, Thomas; Talavera, Karel

    2011-02-22

    Mustard oil (MO) is a plant-derived irritant that has been extensively used in experimental models to induce pain and inflammation. The noxious effects of MO are currently ascribed to specific activation of the cation channel TRPA1 in nociceptive neurons. In contrast to this view, we show here that the capsaicin receptor TRPV1 has a surprisingly large contribution to aversive and pain responses and visceral irritation induced by MO. Furthermore, we found that this can be explained by previously unknown properties of this compound. First, MO has a bimodal effect on TRPA1, producing current inhibition at millimolar concentrations. Second, it directly and stably activates mouse and human recombinant TRPV1, as well as TRPV1 channels in mouse sensory neurons. Finally, physiological temperatures enhance MO-induced TRPV1 stimulation. Our results refute the dogma that TRPA1 is the sole nocisensor for MO and motivate a revision of the putative roles of these channels in models of MO-induced pain and inflammation. We propose that TRPV1 has a generalized role in the detection of irritant botanical defensive traits and in the coevolution of multiple mammalian and plant species. PMID:21315593

  5. ThermoTRP Channels in Nociceptors: Taking a Lead from Capsaicin Receptor TRPV1

    PubMed Central

    Mandadi, Sravan; Roufogalis, Basil D.

    2008-01-01

    Nociceptors with peripheral and central projections express temperature sensitive transient receptor potential (TRP) ion channels, also called thermoTRP’s. Chemosensitivity of thermoTRP’s to certain natural compounds eliciting pain or exhibiting thermal properties has proven to be a good tool in characterizing these receptors. Capsaicin, a pungent chemical in hot peppers, has assisted in the cloning of the first thermoTRP, TRPV1. This discovery initiated the search for other receptors encoding the response to a wide range of temperatures encountered by the body. Of these, TRPV1 and TRPV2 encode unique modalities of thermal pain when exposed to noxious heat. The ability of TRPA1 to encode noxious cold is presently being debated. The role of TRPV1 in peripheral inflammatory pain and central sensitization during chronic pain is well known. In addition to endogenous agonists, a wide variety of chemical agonists and antagonists have been discovered to activate and inhibit TRPV1. Efforts are underway to determine conditions under which agonist-mediated desensitization of TRPV1 or inhibition by antagonists can produce analgesia. Also, identification of specific second messenger molecules that regulate phosphorylation of TRPV1 has been the focus of intense research, to exploit a broader approach to pain treatment. The search for a role of TRPV2 in pain remains dormant due to the lack of suitable experimental models. However, progress into TRPA1’s role in pain has received much attention recently. Another thermoTRP, TRPM8, encoding for the cool sensation and also expressed in nociceptors, has recently been shown to reduce pain via a central mechanism, thus opening a novel strategy for achieving analgesia. The role of other thermoTRP’s (TRPV3 and TRPV4) encoding for detection of warm temperatures and expressed in nociceptors cannot be excluded. This review will discuss current knowledge on the role of nociceptor thermoTRPs in pain and therapy and describes the

  6. Adlea (ALGRX-4975), an injectable capsaicin (TRPV1 receptor agonist) formulation for longlasting pain relief.

    PubMed

    Remadevi, Radhika; Szallisi, Arpad

    2008-02-01

    Anesiva Inc is developing Adlea (ALRGX-4975) - an injectable preparation of capsaicin, a TRPV1 (transient receptor potential vanilloid subfamily 1) receptor agonist - for the potential management of pain associated with osteoarthritis, tendonitiand postsurgical conditions, as well as for neuropathic pain occurring secondary to nerve injury. Adlea functions by desensitizing those neurons that conduct a long-lasting, throbbing form of pain. In phase II clinical trials, a single injection of Adlea significantly reduced pain levels in patients following total knee arthroplasty (TKA) or bunionectomy, and reduced pain in patients with osteoarthritis (OA) or Morton's neuroma. Phase II trials are ongoing to test Adlea in patients who are undergoing total hip arthroplasty or arthroscopic shoulder surgery and in patients with knee OA. Phase III clinical trials for the compound have been slated to begin in 2008 in patients following TKA or bunionectomy. Adlea appears to exhibit promise as a new medication in the treatment of conditions of chronic neuropathic pain. PMID:18240098

  7. Increased capsaicin receptor TRPV1-expressing sensory fibres in irritable bowel syndrome and their correlation with abdominal pain

    PubMed Central

    Akbar, A; Yiangou, Y; Facer, P; Walters, J R F; Anand, P; Ghosh, S

    2008-01-01

    Objective: The capsaicin receptor TRPV1 (transient receptor potential vanilloid type-1) may play an important role in visceral pain and hypersensitivity states. In irritable bowel syndrome (IBS), abdominal pain is a common and distressing symptom where the pathophysiology is still not clearly defined. TRPV1-immunoreactive nerve fibres were investigated in colonic biopsies from patients with IBS, and this was related to abdominal pain. Methods: Rectosigmoid biopsies were collected from 23 IBS patients fulfilling Rome II criteria, and from 22 controls. Abdominal pain scores were recorded using a validated questionnaire. TRPV1-, substance P- and neuronal marker protein gene product (PGP) 9.5-expressing nerve fibres, mast cells (c-kit) and lymphocytes (CD3 and CD4) were quantified, following immunohistochemistry with specific antibodies. The biopsy findings were related to the abdominal pain scores. Results: A significant 3.5-fold increase in median numbers of TRPV1-immunoreactive fibres was found in biopsies from IBS patients compared with controls (p<0.0001). Substance P-immunoreactive fibres (p = 0.01), total nerve fibres (PGP9.5) (p = 0.002), mast cells (c-kit) (p = 0.02) and lymphocytes (CD3) (p = 0.03) were also significantly increased in the IBS group. In multivariate regression analysis, only TRPV1-immuno-reactive fibres (p = 0.005) and mast cells (p = 0.008) were significantly related to the abdominal pain score. Conclusions: Increased TRPV1 nerve fibres are observed in IBS, together with a low-grade inflammatory response. The increased TRPV1 nerve fibres may contribute to visceral hypersensitivity and pain in IBS, and provide a novel therapeutic target. PMID:18252749

  8. A Bivalent Tarantula Toxin Activates the Capsaicin Receptor, TRPV1, by Targeting the Outer Pore Domain

    PubMed Central

    Bohlen, Christopher J.; Priel, Avi; Zhou, Sharleen; King, David; Siemens, Jan; Julius, David

    2010-01-01

    SUMMARY Toxins have evolved to target regions of membrane ion channels that underlie ligand binding, gating, or ion permeation, and have thus served as invaluable tools for probing channel structure and function. Here we describe a peptide toxin from the Earth Tiger tarantula that selectively and irreversibly activates the capsaicin- and heat-sensitive channel, TRPV1. This high avidity interaction derives from a unique tandem repeat structure of the toxin that endows it with an antibody-like bivalency, illustrating a new paradigm in toxin structure and evolution. The ‘double-knot’ toxin traps TRPV1 in the open state by interacting with residues in the presumptive pore-forming region of the channel, highlighting the importance of conformational changes in the outer pore region of TRP channels during activation. PMID:20510930

  9. Activation of TRPV1 by capsaicin induces functional Kinin B1 receptor in rat spinal cord microglia

    PubMed Central

    2012-01-01

    Background The kinin B1 receptor (B1R) is upregulated by pro-inflammatory cytokines and oxydative stress, which are enhanced by transient receptor potential vanilloid subtype 1 (TRPV1) activation. To examine the link between TRPV1 and B1R in inflammatory pain, this study aimed to determine the ability of TRPV1 to regulate microglial B1R expression in the spinal cord dorsal horn, and the underlying mechanism. Methods B1R expression (mRNA, protein and binding sites) was measured in cervical, thoracic and lumbar spinal cord in response to TRPV1 activation by systemic capsaicin (1-50 mg/kg, s.c) in rats pre-treated with TRPV1 antagonists (capsazepine or SB-366791), the antioxidant N-acetyl-L-cysteine (NAC), or vehicle. B1R function was assessed using a tail-flick test after intrathecal (i.t.) injection of a selective B1R agonist (des-Arg9-BK), and its microglial localization was investigated by confocal microscopy with the selective fluorescent B1R agonist, [Nα-bodipy]-des-Arg9-BK. The effect of i.t. capsaicin (1 μg/site) was also investigated. Results Capsaicin (10 to 50 mg/kg, s.c.) enhanced time-dependently (0-24h) B1R mRNA levels in the lumbar spinal cord; this effect was prevented by capsazepine (10 mg/kg, i.p.; 10 μg/site, i.t.) and SB-366791 (1 mg/kg, i.p.; 30 μg/site, i.t.). Increases of B1R mRNA were correlated with IL-1β mRNA levels, and they were significantly less in cervical and thoracic spinal cord. Intrathecal capsaicin (1 μg/site) also enhanced B1R mRNA in lumbar spinal cord. NAC (1 g/kg/d × 7 days) prevented B1R up-regulation, superoxide anion production and NF-kB activation induced by capsaicin (15 mg/kg). Des-Arg9-BK (9.6 nmol/site, i.t.) decreased by 25-30% the nociceptive threshold at 1 min post-injection in capsaicin-treated rats (10-50 mg/kg) while it was without effect in control rats. Des-Arg9-BK-induced thermal hyperalgesia was blocked by capsazepine, SB-366791 and by antagonists/inhibitors of B1R (SSR240612, 10 mg/kg, p.o.), glutamate

  10. Tris-hydroxymethyl-aminomethane enhances capsaicin-induced intracellular Ca(2+) influx through transient receptor potential V1 (TRPV1) channels.

    PubMed

    Murakami, Satoshi; Sudo, Yuka; Miyano, Kanako; Nishimura, Hitomi; Matoba, Motohiro; Shiraishi, Seiji; Konno, Hiroki; Uezono, Yasuhito

    2016-02-01

    Non-selective transient receptor potential vanilloid (TRPV) cation channels are activated by various insults, including exposure to heat, acidity, and the compound capsaicin, resulting in sensations of pain in the skin, visceral organs, and oral cavity. Recently, TRPV1 activation was also demonstrated in response to basic pH elicited by ammonia and intracellular alkalization. Tris-hydroxymethyl aminomethane (THAM) is widely used as an alkalizing agent; however, the effects of THAM on TRPV1 channels have not been defined. In this study, we characterized the effects of THAM-induced TRPV1 channel activation in baby hamster kidney cells expressing human TRPV1 (hTRPV1) and the Ca(2+)-sensitive fluorescent sensor GCaMP2 by real-time confocal microscopy. Notably, both capsaicin (1 μM) and pH 6.5 buffer elicited steep increases in the intracellular Ca(2+) concentration ([Ca(2+)]i), while treatment with THAM (pH 8.5) alone had no effect. However, treatment with THAM (pH 8.5) following capsaicin application elicited a profound, long-lasting increase in [Ca(2+)]i that was completely inhibited by the TRPV1 antagonist capsazepine. Taken together, these results suggest that hTRPV1 pre-activation is required to provoke enhanced, THAM-induced [Ca(2+)]i increases, which could be a mechanism underlying pain induced by basic pH. PMID:26738986

  11. Binding of Capsaicin to the TRPV1 Ion Channel.

    PubMed

    Darré, Leonardo; Domene, Carmen

    2015-12-01

    Transient receptor potential (TRP) ion channels constitute a notable family of cation channels involved in the ability of an organisms to detect noxious mechanical, thermal, and chemical stimuli that give rise to the perception of pain, taste, and changes in temperature. One of the most experimentally studied agonist of TRP channels is capsaicin, which is responsible for the burning sensation produced when chili pepper is in contact with organic tissues. Thus, understanding how this molecule interacts and regulates TRP channels is essential to high impact pharmacological applications, particularly those related to pain treatment. The recent publication of a three-dimensional structure of the vanilloid receptor 1 (TRPV1) in the absence and presence of capsaicin from single particle electron cryomicroscopy experiments provides the opportunity to explore these questions at the atomic level. In the present work, molecular docking and unbiased and biased molecular dynamics simulations were employed to generate a structural model of the capsaicin-channel complex. In addition, the standard free energy of binding was estimated using alchemical transformations coupled with conformational, translational, and orientational restraints on the ligand. Key binding modes consistent with previous experimental data are identified, and subtle but essential dynamical features of the binding site are characterized. These observations shed some light into how TRPV1 interacts with capsaicin, and may help to refine design parameters for new TRPV1 antagonists, and potentially guide further developments of TRP channel modulators. PMID:26502196

  12. Influence of pregnancy and labor on the occurrence of nerve fibers expressing the capsaicin receptor TRPV1 in human corpus and cervix uteri

    PubMed Central

    Tingåker, Berith K; Ekman-Ordeberg, Gunvor; Facer, Paul; Irestedt, Lars; Anand, Praveen

    2008-01-01

    Background Cervical ripening is a prerequisite for a normal obstetrical outcome. This process, including labor, is a painful event that shares features with inflammatory reactions where peripheral nociceptive pathways are involved. The capsaicin and heat receptor TRPV1 is a key molecule in sensory nerves involved in peripheral nociception, but little is known regarding its role in the pregnant uterus. Therefore, the aim of this study was to investigate human corpus and cervix uteri during pregnancy and labor and non-pregnant controls for the presence of TRPV1. Methods We have investigated human uterine corpus and cervix biopsies at term pregnancy and parturition. Biopsies were taken from the upper edge of the hysterotomy during caesarean section at term (n = 8), in labor (n = 8) and from the corresponding area in the non-pregnant uterus after hysterectomy (n = 8). Cervical biopsies were obtained transvaginally from the anterior cervical lip. Serial frozen sections were examined immunohistochemically using specific antibodies to TRPV1 and nerve markers (neurofilaments/peripherin). Results In cervix uteri, TRPV1-immunoreactive fibers were scattered throughout the stroma and around blood vessels, and appeared more frequent in the sub-epithelium. Counts of TRPV1-immunoreactive nerve fibers were not significantly different between the three groups. In contrast, few TRPV1-immunoreactive fibers were found in nerve fascicles in the non-pregnant corpus, and none in the pregnant corpus. Conclusion In this study, TRPV1 innervation in human uterus during pregnancy and labor is shown for the first time. During pregnancy and labor there was an almost complete disappearance of TRPV1 positive nerve fibers in the corpus. However, cervical innervation remained throughout pregnancy and labor. The difference in TRPV1 innervation between the corpus and the cervix is thus very marked. Our data suggest that TRPV1 may be involved in pain mechanisms associated with cervical ripening and

  13. Attenuation of natural killer cell functions by capsaicin through a direct and TRPV1-independent mechanism.

    PubMed

    Kim, Hun Sik; Kwon, Hyung-Joon; Kim, Gye Eun; Cho, Mi-Hyang; Yoon, Seung-Yong; Davies, Alexander J; Oh, Seog Bae; Lee, Heuiran; Cho, Young Keol; Joo, Chul Hyun; Kwon, Seog Woon; Kim, Sun Chang; Kim, Yoo Kyum

    2014-07-01

    The assessment of the biological activity of capsaicin, the compound responsible for the spicy flavor of chili pepper, produced controversial results, showing either carcinogenicity or cancer prevention. The innate immune system plays a pivotal role in cancer pathology and prevention; yet, the effect of capsaicin on natural killer (NK) cells, which function in cancer surveillance, is unclear. This study found that capsaicin inhibited NK cell-mediated cytotoxicity and cytokine production (interferon-γ and tumor necrosis factor-α). Capsaicin impaired the cytotoxicity of NK cells, thereby inhibiting lysis of standard target cells and gastric cancer cells by modulating calcium mobilization in NK cells. Capsaicin also induced apoptosis in gastric cancer cells, but that effect required higher concentrations and longer exposure times than those required to trigger NK cell dysfunction. Furthermore, capsaicin inhibited the cytotoxicity of isolated NK cells and of an NK cell line, suggesting a direct effect on NK cells. Antagonists of transient receptor potential vanilloid subfamily member 1 (TRPV1), a cognate capsaicin receptor, or deficiency in TRPV1 expression failed to prevent the defects induced by capsaicin in NK cells expressing functional TRPV1. Thus, the mechanism of action of capsaicin on NK cells is largely independent of TRPV1. Taken together, capsaicin may have chemotherapeutic potential but may impair NK cell function, which plays a central role in tumor surveillance. PMID:24743513

  14. Capsaicin interaction with TRPV1 channels in a lipid bilayer: molecular dynamics simulation.

    PubMed

    Hanson, Sonya M; Newstead, Simon; Swartz, Kenton J; Sansom, Mark S P

    2015-03-24

    Transient receptor potential vanilloid subtype 1 (TRPV1) is a heat-sensitive ion channel also involved in pain sensation, and is the receptor for capsaicin, the active ingredient of hot chili peppers. The recent structures of TRPV1 revealed putative ligand density within the S1 to S4 voltage-sensor-like domain of the protein. However, questions remain regarding the dynamic role of the lipid bilayer in ligand binding to TRPV1. Molecular dynamics simulations were used to explore behavior of capsaicin in a 1-palmitoyl-2-oleoyl phosphatidylcholine bilayer and with the target S1-S4 transmembrane helices of TRPV1. Equilibrium simulations reveal a preferred interfacial localization for capsaicin. We also observed a capsaicin molecule flipping from the extracellular to the intracellular leaflet, and subsequently able to access the intracellular TRPV1 binding site. Calculation of the potential of mean force (i.e., free energy profile) of capsaicin along the bilayer normal confirms that it prefers an interfacial localization. The free energy profile indicates that there is a nontrivial but surmountable barrier to the flipping of capsaicin between opposing leaflets of the bilayer. Molecular dynamics of the S1-S4 transmembrane helices of the TRPV1 in a lipid bilayer confirm that Y511, known to be crucial to capsaicin binding, has a distribution along the bilayer normal similar to that of the aromatic group of capsaicin. Simulations were conducted of the TRPV1 S1-S4 transmembrane helices in the presence of capsaicin placed in the aqueous phase, in the lipid, or docked to the protein. No stable interaction between ligand and protein was seen for simulations initiated with capsaicin in the bilayer. However, interactions were seen between TRPV1 and capsaicin starting from the cytosolic aqueous phase, and capsaicin remained stable in the majority of simulations from the docked pose. We discuss the significance of capsaicin flipping from the extracellular to the intracellular

  15. Assay of TRPV1 Receptor Signaling.

    PubMed

    Moriello, Aniello Schiano; De Petrocellis, Luciano

    2016-01-01

    The transient receptor potential vanilloid-1 ion channel (TRPV1) is a non-selective ligand-gated cation channel. It is an integrator of a wide variety of exogenous and endogenous physical and chemical stimuli, including capsaicin, noxious heat (>42 °C), and protons (pH < 5.2). TRPV1 is expressed predominantly in primary sensory neurons involved in pain sensation, but also in other neuronal cell types, in the plasma membrane of different non-neuronal cells such as immune cells, keratinocytes, smooth muscle cells, and in the urothelium. Some of these cell types are involved in inflammation. When activated, TRPV1 leads to the gating of cations, including Ca(2+), thus generating changes in intracellular Ca(2+) concentration. Calcium ions play fundamental roles in many cellular processes, virtually in all cells. The use of Ca(2+) fluorescent indicators is a tool for monitoring intracellular Ca(2+) concentration.In this chapter, we describe a method for recording and monitoring Ca(2+) signals through the single wavelength fluorescent indicator Fluo-4 acetoxymethyl (AM), and the ratiometric fluorescent indicator Fura-2 AM in HEK-293 cells transfected with TRPV1 and other TRP channels. TRPV1 pharmacological modulation may potentially represent a strategy for the control of pain and inflammatory conditions in a variety of diseases and injury states. PMID:27245892

  16. Understanding TRPV1 activation by ligands: Insights from the binding modes of capsaicin and resiniferatoxin

    PubMed Central

    Elokely, Khaled; Velisetty, Phanindra; Delemotte, Lucie; Palovcak, Eugene; Klein, Michael L.; Rohacs, Tibor; Carnevale, Vincenzo

    2016-01-01

    The transient receptor potential cation channel subfamily V member 1 (TRPV1) or vanilloid receptor 1 is a nonselective cation channel that is involved in the detection and transduction of nociceptive stimuli. Inflammation and nerve damage result in the up-regulation of TRPV1 transcription, and, therefore, modulators of TRPV1 channels are potentially useful in the treatment of inflammatory and neuropathic pain. Understanding the binding modes of known ligands would significantly contribute to the success of TRPV1 modulator drug design programs. The recent cryo-electron microscopy structure of TRPV1 only provides a coarse characterization of the location of capsaicin (CAPS) and resiniferatoxin (RTX). Herein, we use the information contained in the experimental electron density maps to accurately determine the binding mode of CAPS and RTX and experimentally validate the computational results by mutagenesis. On the basis of these results, we perform a detailed analysis of TRPV1–ligand interactions, characterizing the protein ligand contacts and the role of individual water molecules. Importantly, our results provide a rational explanation and suggestion of TRPV1 ligand modifications that should improve binding affinity. PMID:26719417

  17. Understanding TRPV1 activation by ligands: Insights from the binding modes of capsaicin and resiniferatoxin.

    PubMed

    Elokely, Khaled; Velisetty, Phanindra; Delemotte, Lucie; Palovcak, Eugene; Klein, Michael L; Rohacs, Tibor; Carnevale, Vincenzo

    2016-01-12

    The transient receptor potential cation channel subfamily V member 1 (TRPV1) or vanilloid receptor 1 is a nonselective cation channel that is involved in the detection and transduction of nociceptive stimuli. Inflammation and nerve damage result in the up-regulation of TRPV1 transcription, and, therefore, modulators of TRPV1 channels are potentially useful in the treatment of inflammatory and neuropathic pain. Understanding the binding modes of known ligands would significantly contribute to the success of TRPV1 modulator drug design programs. The recent cryo-electron microscopy structure of TRPV1 only provides a coarse characterization of the location of capsaicin (CAPS) and resiniferatoxin (RTX). Herein, we use the information contained in the experimental electron density maps to accurately determine the binding mode of CAPS and RTX and experimentally validate the computational results by mutagenesis. On the basis of these results, we perform a detailed analysis of TRPV1-ligand interactions, characterizing the protein ligand contacts and the role of individual water molecules. Importantly, our results provide a rational explanation and suggestion of TRPV1 ligand modifications that should improve binding affinity. PMID:26719417

  18. Capsaicin induces NKCC1 internalization and inhibits chloride secretion in colonic epithelial cells independently of TRPV1.

    PubMed

    Bouyer, Patrice G; Tang, Xu; Weber, Christopher R; Shen, Le; Turner, Jerrold R; Matthews, Jeffrey B

    2013-01-15

    Colonic chloride secretion is regulated via the neurohormonal and immune systems. Exogenous chemicals (e.g., butyrate, propionate) can affect chloride secretion. Capsaicin, the pungent ingredient of the chili peppers, exerts various effects on gastrointestinal function. Capsaicin is known to activate the transient receptor potential vanilloid type 1 (TRPV1), expressed in the mesenteric nervous system. Recent studies have also demonstrated its presence in epithelial cells but its role remains uncertain. Because capsaicin has been reported to inhibit colonic chloride secretion, we tested whether this effect of capsaicin could occur by direct action on epithelial cells. In mouse colon and model T84 human colonic epithelial cells, we found that capsaicin inhibited forskolin-dependent short-circuit current (FSK-I(sc)). Using PCR and Western blot, we demonstrated the presence of TRPV1 in colonic epithelial cells. In T84 cells, TRPV1 localized at the basolateral membrane and in vesicular compartments. In permeabilized monolayers, capsaicin activated apical chloride conductance, had no effect on basolateral potassium conductance, but induced NKCC1 internalization demonstrated by immunocytochemistry and basolateral surface biotinylation. AMG-9810, a potent inhibitor of TRPV1, did not prevent the inhibition of the FSK-I(sc) by capsaicin. Neither resiniferatoxin nor N-oleoyldopamine, two selective agonists of TRPV1, blocked the FSK-I(sc). Conversely capsaicin, resiniferatoxin, and N-oleoyldopamine raised intracellular calcium ([Ca(2+)](i)) in T84 cells and AMG-9810 blocked the rise in [Ca(2+)](i) induced by capsaicin and resiniferatoxin suggesting the presence of a functional TRPV1 channel. We conclude that capsaicin inhibits chloride secretion in part by causing NKCC1 internalization, but by a mechanism that appears to be independent of TRPV1. PMID:23139219

  19. Capsaicin induces NKCC1 internalization and inhibits chloride secretion in colonic epithelial cells independently of TRPV1

    PubMed Central

    Tang, Xu; Weber, Christopher R.; Shen, Le; Turner, Jerrold R.; Matthews, Jeffrey B.

    2013-01-01

    Colonic chloride secretion is regulated via the neurohormonal and immune systems. Exogenous chemicals (e.g., butyrate, propionate) can affect chloride secretion. Capsaicin, the pungent ingredient of the chili peppers, exerts various effects on gastrointestinal function. Capsaicin is known to activate the transient receptor potential vanilloid type 1 (TRPV1), expressed in the mesenteric nervous system. Recent studies have also demonstrated its presence in epithelial cells but its role remains uncertain. Because capsaicin has been reported to inhibit colonic chloride secretion, we tested whether this effect of capsaicin could occur by direct action on epithelial cells. In mouse colon and model T84 human colonic epithelial cells, we found that capsaicin inhibited forskolin-dependent short-circuit current (FSK-Isc). Using PCR and Western blot, we demonstrated the presence of TRPV1 in colonic epithelial cells. In T84 cells, TRPV1 localized at the basolateral membrane and in vesicular compartments. In permeabilized monolayers, capsaicin activated apical chloride conductance, had no effect on basolateral potassium conductance, but induced NKCC1 internalization demonstrated by immunocytochemistry and basolateral surface biotinylation. AMG-9810, a potent inhibitor of TRPV1, did not prevent the inhibition of the FSK-Isc by capsaicin. Neither resiniferatoxin nor N-oleoyldopamine, two selective agonists of TRPV1, blocked the FSK-Isc. Conversely capsaicin, resiniferatoxin, and N-oleoyldopamine raised intracellular calcium ([Ca2+]i) in T84 cells and AMG-9810 blocked the rise in [Ca2+]i induced by capsaicin and resiniferatoxin suggesting the presence of a functional TRPV1 channel. We conclude that capsaicin inhibits chloride secretion in part by causing NKCC1 internalization, but by a mechanism that appears to be independent of TRPV1. PMID:23139219

  20. Biochemical pharmacology of the vanilloid receptor TRPV1. An update.

    PubMed

    Cortright, Daniel N; Szallasi, Arpad

    2004-05-01

    There is mounting evidence that the vanilloid (capsaicin) receptor; transient receptor potential channel, vanilloid subfamily member 1 (TRPV1), is subjected to multiple interacting levels of control. The first level is by reversible phosphorylation catalyzed by intrinsic kinases (e.g. protein kinase A and C) and phosphatases (e.g. calcineurin), which plays a pivotal role in receptor sensitization vs. tachyphylaxis. In addition, this mechanism links TRPV1 to intracellular signaling by various important endogenous as well as exogenous substances such as bradykinin, ethanol, nicotin and insulin. It is not clear, however, whether phosphorylation per se is sufficient to liberate TRPV1 under the inhibitory control of phosphatydylinositol-4,5-bisphosphate. The second level of control is by forming TRPV1 heteromers and their association with putative regulatory proteins. The next level of regulation is by subcellular compartmentalization. The membrane form of TRPV1 functions as a nonselective cation channel. On the endoplasmic reticulum, TRPV1 is present in two differentially regulated forms, one of which is inositol triphosphate-dependent whereas the other is not. These three TRPV1 compartments provide a versatile regulation of intracellular Ca(2+) levels. Last, there is a complex and poorly understood regulation of TRPV1 activity via control of gene expression. Factors that downregulate TRPV1 expression include vanilloid treatment and growth factor (notably, nerve growth factor) deprivation. By contrast, TRPV1 appears to be upregulated during inflammatory conditions. Interestingly, following experimental nerve injury and in animal models of diabetic neuropathy TRPV1 is present on neurons that do not normally express TRPV1. Combined, these findings imply an important role for aberrant TRPV1 expression in the development of neuropathic pain and hyperalgesia. In humans, disease-related changes in TRPV1 expression have already been described (e.g. inflammatory bowel disease

  1. Reciprocal effects of capsaicin and menthol on thermosensation through regulated activities of TRPV1 and TRPM8.

    PubMed

    Takaishi, Masayuki; Uchida, Kunitoshi; Suzuki, Yoshiro; Matsui, Hiroshi; Shimada, Tadashi; Fujita, Fumitaka; Tominaga, Makoto

    2016-03-01

    Transient receptor potential vanilloid 1 (TRPV1) is activated by elevated temperature (>42 °C), and it has been reported that cold temperature decreases capsaicin-induced TRPV1 activity. In contrast, transient receptor potential melastatin 8 (TRPM8) is activated by low temperatures and menthol, and heat stimulation suppresses menthol-evoked TRPM8 currents. These findings suggest that the effects of specific agents on TRPV1 and TRPM8 channels are intricately interrelated. We examined the effects of menthol on human (h)TRPV1 and of capsaicin on hTRPM8. hTRPV1 currents activated by heat and capsaicin were inhibited by menthol, whereas hTRPM8 currents activated by cold and menthol were similarly inhibited by capsaicin. An in vivo sensory irritation test showed that menthol conferred an analgesic effect on the sensory irritation evoked by a capsaicin analogue. These results indicate that in our study the agonists of TRPV1 and TRPM8 interacted with both of these channels and suggest that the anti-nociceptive effects of menthol can be partially explained by this phenomenon. PMID:26645885

  2. Induction of total insensitivity to capsaicin and hypersensitivity to garlic extract in human by decreased expression of TRPV1.

    PubMed

    Park, Joong Jean; Lee, Jaehee; Kim, Myung Ah; Back, Seung Keun; Hong, Seung Kil; Na, Heung Sik

    2007-01-10

    TRPV1 is a cation channel which is activated by temperature (> or =42 degrees C) and capsaicin. In the present study, we found a person with total insensitivity to capsaicin and attempted to unravel its causes. The expression levels of TRPV1 protein and mRNA in the cells of the person's buccal mucosa were less than half of those in a normal subject. Sequential analysis of mRNA and genomic DNA revealed several point mutations mostly in the second intron of the person's TRPV1. Interestingly, the subject showed hypersensitivity to garlic extract, but TRPA1 (allicin receptor) level was normal. These results suggest that the decreased expression of TRPV1 may be related to a functional knock out in capsaicin sensation and hypersensitivity to allicin in humans. PMID:17110039

  3. Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations

    PubMed Central

    Cui, Yuanyuan; Yang, Fan; Cao, Xu; Yarov-Yarovoy, Vladimir

    2012-01-01

    The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate. PMID:22412190

  4. Structure-activity relationships of vanilloid receptor agonists for arteriolar TRPV1

    PubMed Central

    Czikora, Á; Lizanecz, E; Bakó, P; Rutkai, I; Ruzsnavszky, F; Magyar, J; Pórszász, R; Kark, T; Facskó, A; Papp, Z; Édes, I; Tóth, A

    2012-01-01

    BACKGROUND AND PURPOSE The transient receptor potential vanilloid 1 (TRPV1) plays a role in the activation of sensory neurons by various painful stimuli and is a therapeutic target. However, functional TRPV1 that affect microvascular diameter are also expressed in peripheral arteries and we attempted to characterize this receptor. EXPERIMENTAL APPROACH Sensory TRPV1 activation was measured in rats by use of an eye wiping assay. Arteriolar TRPV1-mediated smooth muscle specific responses (arteriolar diameter, changes in intracellular Ca2+) were determined in isolated, pressurized skeletal muscle arterioles obtained from the rat and wild-type or TRPV1−/− mice and in canine isolated smooth muscle cells. The vascular pharmacology of the TRPV1 agonists (potency, efficacy, kinetics of action and receptor desensitization) was determined in rat isolated skeletal muscle arteries. KEY RESULTS Capsaicin evoked a constrictor response in isolated arteries similar to that mediated by noradrenaline, this was absent in arteries from TRPV1 knockout mice and competitively inhibited by TRPV1 antagonist AMG9810. Capsaicin increased intracellular Ca2+ in the arteriolar wall and in isolated smooth muscle cells. The TRPV1 agonists evoked similar vascular constrictions (MSK-195 and JYL-79) or were without effect (resiniferatoxin and JYL-273), although all increased the number of responses (sensory activation) in the eye wiping assay. Maximal doses of all agonists induced complete desensitization (tachyphylaxis) of arteriolar TRPV1 (with the exception of capsaicin). Responses to the partial agonist JYL-1511 suggested 10% TRPV1 activation is sufficient to evoke vascular tachyphylaxis without sensory activation. CONCLUSIONS AND IMPLICATIONS Arteriolar TRPV1 have different pharmacological properties from those located on sensory neurons in the rat. PMID:21883148

  5. Role of TRPV1 receptors in descending modulation of pain.

    PubMed

    Palazzo, Enza; Rossi, Francesco; Maione, Sabatino

    2008-04-16

    Transient receptor potential vanilloid type 1 (TRPV1) receptor is a ligand-gated non-selective cation channel activated by heat (>43 degrees C), low pH and endogenous lipid molecules such as anandamide, N-arachidonoyl-dopamine, N-acyl-dopamines and products of lipoxygenases (12- and 15-(S)-HPETE) termed endovanilloids. Apart from peripheral primary afferent neurons and dorsal root ganglia, TRPV1 receptor is expressed throughout the brain. Recent evidence shows that TRPV1 receptor stimulation by endocannabinoids or by capsaicin within the periaqueductal grey (PAG) leads to analgesia and this effect is associated with glutamate increase and the activation of OFF cell population in the rostral ventromedial medulla (RVM). Activation of the antinociceptive descending pathway via TPRV1 receptor stimulation in the PAG may be a novel strategy for producing analgesia. This review will summarize the more recent insights into the role of TRPV1 receptor within the antinociceptive descending pathway and its possible exploitation as a target for novel pain-killer agents. PMID:18325659

  6. Presynaptic TRPV1 vanilloid receptor function is age- but not CB1 cannabinoid receptor-dependent in the rodent forebrain.

    PubMed

    Köles, László; Garção, Pedro; Zádori, Zoltán S; Ferreira, Samira G; Pinheiro, Bárbara S; da Silva-Santos, Carla S; Ledent, Catherine; Köfalvi, Attila

    2013-08-01

    Neocortical and striatal TRPV1 (vanilloid or capsaicin) receptors (TRPV1Rs) are excitatory ligand-gated ion channels, and are implicated in psychiatric disorders. However, the purported presynaptic neuromodulator role of TRPV1Rs in glutamatergic, serotonergic or dopaminergic terminals of the rodent forebrain remains little understood. With the help of patch-clamp electrophysiology and neurochemical approaches, we mapped the age-dependence of presynaptic TRPV1R function, and furthermore, we aimed at exploring whether the presence of CB1 cannabinoid receptors (CB1Rs) influences the function of the TRPV1Rs, as both receptor types share endogenous ligands. We found that the major factor which affects presynaptic TRPV1R function is age: by post-natal day 13, the amplitude of capsaicin-induced release of dopamine and glutamate is halved in the rat striatum, and two weeks later, capsaicin already loses its effect. However, TRPV1R receptor function is not enhanced by chemical or genetic ablation of the CB1Rs in dopaminergic, glutamatergic and serotonergic terminals of the mouse brain. Altogether, our data indicate a possible neurodevelopmental role for presynaptic TRPV1Rs in the rodent brain, but we found no cross-talk between TRPV1Rs and CB1Rs in the same nerve terminal. PMID:23831917

  7. Functional characterisation of the S512Y mutant vanilloid human TRPV1 receptor.

    PubMed

    Sutton, Kathy G; Garrett, Elizabeth M; Rutter, A Richard; Bonnert, Timothy P; Jarolimek, Wolfgang; Seabrook, Guy R

    2005-11-01

    1 Mammalian transient receptor potential (TRP) channels include the nonselective cation channel TRPV1, which is activated by a range of stimuli including low pH, vanilloids and heat. Previously, selective mutagenesis experiments identified an intracellular residue (S512Y) critical to discriminating between pH and vanilloid (capsaicin) gating of the rat TRPV1 receptor. 2 In this study, switching the equivalent residue in the human TRPV1 (which has some significant differences with the rat TRPV1) also rendered this channel relatively insensitive to activation by capsaicin and proved critical in determining the receptor's sensitivity to the putative endovanilloid N-arachidonoyl-dopamine (NADA), suggesting a similar mode of activation for these two agonists. 3 Potency of pH gating was reduced; however, voltage-dependent outward rectification properties of the pH-dependent current and gating by heat and pH sensitisation of the S512Y heat response remained unaffected. 4 Surprisingly, residual capsaicin gating was detected and could be sensitised by pH even in the presence of a competitive antagonist. Taken together, these findings indicate that effective functional interaction of capsaicin with the S512Y channel still occurred, although the vanilloid-dependent gating per se was severely compromised. 5 This observation provides additional evidence for capsaicin interacting at multiple sites, distinct from the S512 residue located close to the intracellular face of the pore. PMID:16100528

  8. Therapeutic potential of vanilloid receptor TRPV1 agonists and antagonists as analgesics: Recent advances and setbacks.

    PubMed

    Wong, Gilbert Y; Gavva, Narender R

    2009-04-01

    The vanilloid receptor TRPV1 is a homotetrameric, non-selective cation channel abundantly expressed in the nociceptors (c-fibers). TRPV1 is considered as a highly validated pain target because, i) its agonists such as capsaicin cause desensitization of TRPV1 channels that relieves pain behaviors in preclinical species, and ii) its antagonists relieve pain behaviors in rodent models of inflammation, osteoarthritis, and cancer. Hence, both agonists and antagonists of TRPV1 are being evaluated as potential analgesics in clinical trials. Clinical trial results of TRPV1 agonists such as resiniferatoxin in interstitial cystitis, NGX 4010 in post-herpetic neuralgia, and 4975 (Adlea) in osteoarthritis, bunionectomy, and Morton's neuroma have been reported. Similarly, clinical trial results of TRPV1 antagonists such as SB-705498 and AMG 517 have also been published recently. Overall, some molecules (e.g., capsaicin) demonstrated potential analgesia in certain conditions (postsurgical pain, postherpetic neuralgia, pain in diabetic neuropathy, osteoarthritis, bunionectomy, and Morton's neuroma), whereas others fell out of the clinic due to on-target liabilities or failed to demonstrate efficacy. This review summarizes recent advances and setbacks of TRPV1 agonists and antagonists in the clinic and predicts future directions. PMID:19150372

  9. Retinoids activate the irritant receptor TRPV1 and produce sensory hypersensitivity.

    PubMed

    Yin, Shijin; Luo, Jialie; Qian, Aihua; Du, Junhui; Yang, Qing; Zhou, Shentai; Yu, Weihua; Du, Guangwei; Clark, Richard B; Walters, Edgar T; Carlton, Susan M; Hu, Hongzhen

    2013-09-01

    Retinoids are structurally related derivatives of vitamin A and are required for normal vision as well as cell proliferation and differentiation. Clinically, retinoids are effective in treating many skin disorders and cancers. Application of retinoids evokes substantial irritating side effects, including pain and inflammation; however, the precise mechanisms accounting for the sensory hypersensitivity are not understood. Here we show that both naturally occurring and synthetic retinoids activate recombinant or native transient receptor potential channel vanilloid subtype 1 (TRPV1), an irritant receptor for capsaicin, the pungent ingredient of chili peppers. In vivo, retinoids produced pain-related behaviors that were either eliminated or significantly reduced by genetic or pharmacological inhibition of TRPV1 function. These findings identify TRPV1 as an ionotropic receptor for retinoids and provide cellular and molecular insights into retinoid-evoked hypersensitivity. These findings also suggest that selective TRPV1 antagonists are potential therapeutic drugs for treating retinoid-induced sensory hypersensitivity. PMID:23925292

  10. Capsaicin-Induced Death of Human Haematological Malignant Cell Lines Is Independent of TRPV1 Activation.

    PubMed

    Omari, Sofia A; Adams, Murray J; Kunde, Dale A; Geraghty, Dominic P

    2016-01-01

    The effect of the plant-derived vanilloid, capsaicin (CAP), on the metabolic activity of THP-1, U266B1 and U937 hematological malignancy cells was determined. CAP reduced metabolic activity in a concentration-dependent manner in the three cell lines. A biphasic effect was observed on THP-1 cells (EC50: IC50 (95% CI) 32.9 (19.9-54.3)/219 (144-246) µmol/l). U266B1 cells were more resistant to CAP than THP-1 and U937. Metabolic activity was significantly inhibited by CAP in U937 compared to U266B1 cells (IC50: 197 versus 431 µmol/l, respectively, p < 0.008). Transient receptor potential vanilloid-1 (TRPV1) and CB1 antagonists (SB452533 and AM251, respectively) suppressed the CAP-induced increase in THP-1 cell metabolic activity (p < 0.001). AM251 and SB452533 appeared to act as partial agonists and displayed a synergistic effect with CAP in U937 cells. CAP inhibits the metabolic activity of malignant hematological cells through non-TRPV1-dependent mechanisms. PMID:27160991

  11. Involvement of Transient Receptor Potential Cation Channel Vanilloid 1 (TRPV1) in Myoblast Fusion.

    PubMed

    Kurosaka, Mitsutoshi; Ogura, Yuji; Funabashi, Toshiya; Akema, Tatsuo

    2016-10-01

    The mechanisms that underlie the complex process of muscle regeneration after injury remain unknown. Transient receptor potential cation channel vanilloid 1 (TRPV1) is expressed in several cell types, including skeletal muscle, and is activated by high temperature and by certain molecules secreted during tissue inflammation. Severe inflammation and local temperature perturbations are induced during muscle regeneration, which suggests that TRPV1 might be activated and involved in the process. The aim of this study, was to clarify the role of TRPV1 in the myogenic potential of satellite cells responsible for muscle regeneration. We found that mRNA and protein levels of TRPV1 increased during regeneration after cardiotoxin (CTX)-induced muscle injury in mice. Using isolated mouse satellite cells (i.e., myoblasts), we observed that activation of TRPV1 by its agonist capsaicin (CAP) augmented myogenin protein levels. Whereas CAP did not alter myoblast proliferation, it facilitated myoblast fusion (evaluated using myonucleii number per myotube and fusion index). In contrast, suppression of TRPV1 by siRNA impaired myoblast fusion. Using mice, we also demonstrated that intramuscular injection of CAP facilitated muscle repair after CTX-induced muscle injury. Moreover, we showed that these roles of TRPV1 might be mediated by interleukin-4 and calcium signaling during myoblast fusion. Collectively, these results suggest that TRPV1 underlies normal myogenesis through promotion of myoblast fusion. J. Cell. Physiol. 231: 2275-2285, 2016. © 2016 Wiley Periodicals, Inc. PMID:26892397

  12. Structural determinants of the transient receptor potential 1 (TRPV1) channel activation by phospholipid analogs.

    PubMed

    Morales-Lázaro, Sara L; Serrano-Flores, Barbara; Llorente, Itzel; Hernández-García, Enrique; González-Ramírez, Ricardo; Banerjee, Souvik; Miller, Duane; Gududuru, Veeresh; Fells, James; Norman, Derek; Tigyi, Gabor; Escalante-Alcalde, Diana; Rosenbaum, Tamara

    2014-08-29

    The transient receptor potential vanilloid 1 (TRPV1) ion channel is a polymodal protein that responds to various stimuli, including capsaicin (the pungent compound found in chili peppers), extracellular acid, and basic intracellular pH, temperatures close to 42 °C, and several lipids. Lysophosphatidic acid (LPA), an endogenous lipid widely associated with neuropathic pain, is an agonist of the TRPV1 channel found in primary afferent nociceptors and is activated by other noxious stimuli. Agonists or antagonists of lipid and other chemical natures are known to possess specific structural requirements for producing functional effects on their targets. To better understand how LPA and other lipid analogs might interact and affect the function of TRPV1, we set out to determine the structural features of these lipids that result in the activation of TRPV1. By changing the acyl chain length, saturation, and headgroup of these LPA analogs, we established strict requirements for activation of TRPV1. Among the natural LPA analogs, we found that only LPA 18:1, alkylglycerophosphate 18:1, and cyclic phosphatidic acid 18:1, all with a monounsaturated C18 hydrocarbon chain activate TRPV1, whereas polyunsaturated and saturated analogs do not. Thus, TRPV1 shows a more restricted ligand specificity compared with LPA G-protein-coupled receptors. We synthesized fatty alcohol phosphates and thiophosphates and found that many of them with a single double bond in position Δ9, 10, or 11 and Δ9 cyclopropyl group can activate TRPV1 with efficacy similar to capsaicin. Finally, we developed a pharmacophore and proposed a mechanistic model for how these lipids could induce a conformational change that activates TRPV1. PMID:25035428

  13. Structural insights into transient receptor potential vanilloid type 1 (TRPV1) from homology modeling, flexible docking, and mutational studies

    PubMed Central

    Lee, Jin Hee; Lee, Yoonji; Ryu, HyungChul; Kang, Dong Wook; Lee, Jeewoo; Lazar, Jozsef; Pearce, Larry V.; Pavlyukovets, Vladimir A.; Blumberg, Peter M.; Choi, Sun

    2012-01-01

    The transient receptor potential vanilloid subtype 1 (TRPV1) is a non-selective cation channel composed of four monomers with six transmembrane helices (TM1-TM6). TRPV1 is found in the central and peripheral nervous system, and it is an important therapeutic target for pain relief. We describe here the construction of a tetrameric homology model of rTRPV1. We experimentally evaluated by mutational analysis the contribution of residues of rat TRPV1 (rTRPV1) contributing to ligand binding by the prototypical TRPV1 agonists capsaicin and resiniferatoxin. We then performed docking analysis using our homology model. The docking results with capsaicin and RTX showed that our homology model was reliable, affording good agreement with our mutation data. Additionally, the binding mode of a simplified RTX (sRTX) ligand as predicted by the modeling agreed well with those of capsaicin and RTX, accounting for the high binding affinity of the sRTX ligand for TRPV1. Through the homology modeling, docking and mutational studies, we obtained important insights into the ligand-receptor interactions at the molecular level which should prove of value in the design of novel TRPV1 ligands. PMID:21448716

  14. Endothelin potentiates TRPV1 via ETA receptor-mediated activation of protein kinase C

    PubMed Central

    Plant, Tim D; Zöllner, Christian; Kepura, Frauke; Mousa, Shaaban S; Eichhorst, Jenny; Schaefer, Michael; Furkert, Jens; Stein, Christoph; Oksche, Alexander

    2007-01-01

    Background Endothelin-1 (ET-1) both stimulates nociceptors and sensitizes them to noxious stimuli, an effect probably mediated by the ETA receptor (ETAR) expressed in sensory neurons. The cellular mechanisms of this ET-1-mediated effect are only poorly understood. TRPV1, the heat-, pH- and capsaicin-sensitive cation channel already known to be modulated by a number of cellular mediators released in response to noxious stimuli and during inflammation, is a potential target for the action of ET-1. Results We studied the effects of ET-1 on TRPV1 in sensory neurons from the dorsal root ganglion (DRG) and in HEK293 cells coexpressing TRPV1 and the ETAR. Specific 125I-ET-1 binding sites (817 ± 92 fmol/mg) were detected in membrane preparations of DRG with an ETAR/ETBR ratio of 60:40. In an immunofluorescence analysis, coexpression of TRPV1 and the ETAR was found in a subpopulation of primary sensory neurons. ET-1 strongly potentiated capsaicin-induced TRPV1 currents in some neurons, and in HEK293 cells co-expressing TRPV1 and the ETAR. Weaker potentiation was observed in HEK293 cells coexpressing TRPV1 and the ETBR. ETAR activation also increased responses to low pH and heat. In HEK293 cells, strong potentiation of TRPV1 like that induced by ET-1 via the ETAR could be induced by PKC activation, but not with activators of the adenylyl cyclase or the PKA pathway. Furthermore, inhibition of PKC with bisindolylmaleimide X (BIM X) or mutation of the PKC phosphorylation site S800 completely prevented ETAR-mediated potentiation. Conclusion We conclude that ET-1 potentiates TRPV1 by a PKC-dependent mechanism and that this could play a major role in the algogenic and hyperalgesic effects of ET-1 described in previous studies. PMID:18001466

  15. Inhibition of capsaicin-driven nasal hyper-reactivity by SB-705498, a TRPV1 antagonist

    PubMed Central

    Holland, Carlijn; Drunen, Cornelis Van; Denyer, Jane; Smart, Kevin; Segboer, Christine; Terreehorst, Ingrid; Newlands, Amy; Beerahee, Misba; Fokkens, Wytske; Tsitoura, Daphne C

    2014-01-01

    AIMS To assess the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of intranasal SB-705498, a selective TRPV1 antagonist. METHODS Two randomized, double-blind, placebo-controlled, clinical studies were performed: (i) an intranasal SB-705498 first time in human study to examine the safety and PK of five single escalating doses from 0.5 to 12 mg and of repeat dosing with 6 mg and 12 mg twice daily for 14 days and (ii) a PD efficacy study in subjects with non-allergic rhinitis (NAR) to evaluate the effect of 12 mg intranasal SB-705498 against nasal capsaicin challenge. RESULTS Single and repeat dosing with intranasal SB-705498 was safe and well tolerated. The overall frequency of adverse events was similar for SB-705498 and placebo and no dose-dependent increase was observed. Administration of SB-705498 resulted in less than dose proportional AUC(0,12 h) and Cmax, while repeat dosing from day 1 to day 14 led to its accumulation. SB-705498 receptor occupancy in nasal tissue was estimated to be high (>80%). Administration of 12 mg SB-705498 to patients with NAR induced a marked reduction in total symptom scores triggered by nasal capsaicin challenge. Inhibition of rhinorrhoea, nasal congestion and burning sensation was associated with 2-to 4-fold shift in capsaicin potency. CONCLUSIONS Intranasal SB-705498 has an appropriate safety and PK profile for development in humans and achieves clinically relevant attenuation of capsaicin-provoked rhinitis symptoms in patients with NAR. The potential impact intranasal SB-705498 may have in rhinitis treatment deserves further evaluation. PMID:23909699

  16. Identifying the integrated neural networks involved in capsaicin-induced pain using fMRI in awake TRPV1 knockout and wild-type rats

    PubMed Central

    Yee, Jason R.; Kenkel, William; Caccaviello, John C.; Gamber, Kevin; Simmons, Phil; Nedelman, Mark; Kulkarni, Praveen; Ferris, Craig F.

    2015-01-01

    In the present study, we used functional MRI in awake rats to investigate the pain response that accompanies intradermal injection of capsaicin into the hindpaw. To this end, we used BOLD imaging together with a 3D segmented, annotated rat atlas and computational analysis to identify the integrated neural circuits involved in capsaicin-induced pain. The specificity of the pain response to capsaicin was tested in a transgenic model that contains a biallelic deletion of the gene encoding for the transient receptor potential cation channel subfamily V member 1 (TRPV1). Capsaicin is an exogenous ligand for the TRPV1 receptor, and in wild-type rats, activated the putative pain neural circuit. In addition, capsaicin-treated wild-type rats exhibited activation in brain regions comprising the Papez circuit and habenular system, systems that play important roles in the integration of emotional information, and learning and memory of aversive information, respectively. As expected, capsaicin administration to TRPV1-KO rats failed to elicit the robust BOLD activation pattern observed in wild-type controls. However, the intradermal injection of formalin elicited a significant activation of the putative pain pathway as represented by such areas as the anterior cingulate, somatosensory cortex, parabrachial nucleus, and periaqueductal gray. Notably, comparison of neural responses to capsaicin in wild-type vs. knock-out rats uncovered evidence that capsaicin may function in an antinociceptive capacity independent of TRPV1 signaling. Our data suggest that neuroimaging of pain in awake, conscious animals has the potential to inform the neurobiological basis of full and integrated perceptions of pain. PMID:25745388

  17. The pain receptor TRPV1 displays agonist-dependent activation stoichiometry

    PubMed Central

    Hazan, Adina; Kumar, Rakesh; Matzner, Henry; Priel, Avi

    2015-01-01

    The receptor channel TRPV1 (Transient Receptor Potential Vanilloid 1) is expressed by primary afferent sensory neurons of the pain pathway, where it functions as a sensor of noxious heat and various chemicals, including eicosanoids, capsaicin, protons and peptide toxins. Comprised of four identical subunits that organize into a non-selective cationic permeable channel, this receptor has a variety of binding sites responsible for detecting their respective agonists. Although its physiological role as a chemosensor has been described in detail, the stoichiometry of TRPV1 activation by its different ligands remains unknown. Here, we combined the use of concatemeric constructs harboring mutated binding sites with patch-clamp recordings in order to determine the stoichiometry for TRPV1 activation through the vanilloid binding site and the outer-pore domain by capsaicin and protons, respectively. We show that, while a single capsaicin-bound subunit was sufficient to achieve a maximal open-channel lifetime, all four proton-binding sites were required. Thus, our results demonstrate a distinct stoichiometry of TRPV1 activation through two of its different agonist-binding domains. PMID:26194846

  18. The pain receptor TRPV1 displays agonist-dependent activation stoichiometry.

    PubMed

    Hazan, Adina; Kumar, Rakesh; Matzner, Henry; Priel, Avi

    2015-01-01

    The receptor channel TRPV1 (Transient Receptor Potential Vanilloid 1) is expressed by primary afferent sensory neurons of the pain pathway, where it functions as a sensor of noxious heat and various chemicals, including eicosanoids, capsaicin, protons and peptide toxins. Comprised of four identical subunits that organize into a non-selective cationic permeable channel, this receptor has a variety of binding sites responsible for detecting their respective agonists. Although its physiological role as a chemosensor has been described in detail, the stoichiometry of TRPV1 activation by its different ligands remains unknown. Here, we combined the use of concatemeric constructs harboring mutated binding sites with patch-clamp recordings in order to determine the stoichiometry for TRPV1 activation through the vanilloid binding site and the outer-pore domain by capsaicin and protons, respectively. We show that, while a single capsaicin-bound subunit was sufficient to achieve a maximal open-channel lifetime, all four proton-binding sites were required. Thus, our results demonstrate a distinct stoichiometry of TRPV1 activation through two of its different agonist-binding domains. PMID:26194846

  19. Structural mechanism underlying capsaicin binding and activation of the TRPV1 ion channel.

    PubMed

    Yang, Fan; Xiao, Xian; Cheng, Wei; Yang, Wei; Yu, Peilin; Song, Zhenzhen; Yarov-Yarovoy, Vladimir; Zheng, Jie

    2015-07-01

    Capsaicin bestows spiciness by activating TRPV1 channel with exquisite potency and selectivity. Although a capsaicin-bound channel structure was previously resolved by cryo-EM at 4.2- to 4.5-Å resolution, capsaicin was registered as a small electron density, reflecting neither its chemical structure nor specific ligand-channel interactions--important details required for mechanistic understanding. We obtained the missing atomic-level details by iterative computation and confirmed them by systematic site-specific functional tests. We observed that the bound capsaicin takes a 'tail-up, head-down' configuration. The vanillyl and amide groups form specific interactions to anchor its bound position, while the aliphatic tail may sample a range of conformations, making it invisible in cryo-EM images. Capsaicin stabilizes TRPV1's open state by 'pull-and-contact' interactions between the vanillyl group and the S4-S5 linker. Our study provides a structural mechanism for the agonistic function of capsaicin and its analogs, and demonstrates an effective approach to obtain atomic-level information from cryo-EM structures. PMID:26053297

  20. The mechanism of μ-opioid receptor (MOR)-TRPV1 crosstalk in TRPV1 activation involves morphine anti-nociception, tolerance and dependence.

    PubMed

    Bao, Yanju; Gao, Yebo; Yang, Liping; Kong, Xiangying; Yu, Jing; Hou, Wei; Hua, Baojin

    2015-01-01

    Initiated by the activation of various nociceptors, pain is a reaction to specific stimulus modalities. The μ-opioid receptor (MOR) agonists, including morphine, remain the most potent analgesics to treat patients with moderate to severe pain. However, the utility of MOR agonists is limited by the adverse effects associated with the use of these drugs, including analgesic tolerance and physical dependence. A strong connection has been suggested between the expression of the transient receptor potential vanilloid type 1 (TRPV1) ion channel and the development of inflammatory hyperalgesia. TRPV1 is important for thermal nociception induction, and is mainly expressed on sensory neurons. Recent reports suggest that opioid or TRPV1 receptor agonist exposure has contrasting consequences for anti-nociception, tolerance and dependence. Chronic morphine exposure modulates TRPV1 activation and induces the anti-nociception effects of morphine. The regulation of many downstream targets of TRPV1 plays a critical role in this process, including calcitonin gene-related peptide (CGRP) and substance P (SP). Additional factors also include capsaicin treatment blocking the anti-nociception effects of morphine in rats, as well as opioid modulation of TRPV1 responses through the cAMP-dependent PKA pathway and MAPK signaling pathways. Here, we review new insights concerning the mechanism underlying MOR-TRPV1 crosstalk and signaling pathways and discuss the potential mechanisms of morphine-induced anti-nociception, tolerance and dependence associated with the TRPV1 signaling pathway and highlight how understanding these mechanisms might help find therapeutic targets for the treatment of morphine induced antinociception, tolerance and dependence. PMID:26176938

  1. Expression and functionality of TRPV1 receptor in human MCF-7 and canine CF.41 cells.

    PubMed

    Vercelli, C; Barbero, R; Cuniberti, B; Odore, R; Re, G

    2015-06-01

    As canine mammary tumours (CMT) and human breast cancer share clinical and prognostic features, the former have been proposed as a model to study carcinogenesis and improved therapeutic treatment in human breast cancer. In recent years, it has been shown that transient receptor potential vanilloid 1 (TRPV1) is expressed in different neoplastic tissues and its activation has been associated with regulation of cancer growth and progression. The aim of the present research was to demonstrate the presence of TRPV1 in human and canine mammary cancer cells, MCF-7 and CF.41, respectively, and to study the role of TRPV1 in regulating cell proliferation. The images obtained by Western blot showed a signal at 100 kDa corresponding to the molecular weight of TRPV1 receptor. All tested TRPV1 agonists and antagonists caused a significant decrease (P < 0.05) of cell growth rate in MCF-7 cells. By contrast, in CF.41 cells capsaicin and capsazepine induced a significant increase (P < 0.05) in cell proliferation, whereas resiniferatoxin (RTX) and 5-iodo-resiniferatoxin (5-I-RTX) had no influence on CF.41 cell proliferation. Further studies are needed to elucidate the underlying molecular mechanism responsible for the different effects evoked by TRPV1 activation in MCF-7 and CF.41 cells. PMID:23510405

  2. Modulation of defensive behavior by Transient Receptor Potential Vanilloid Type-1 (TRPV1) channels.

    PubMed

    Aguiar, D C; Moreira, F A; Terzian, A L; Fogaça, M V; Lisboa, S F; Wotjak, C T; Guimaraes, F S

    2014-10-01

    The Transient Receptor Potential Vanilloid Type-1 (TRPV1) was first characterized in primary afferent fibers as a receptor for capsaicin (the pungent ingredient of chili peppers). Later on, this cation-permeable ion channel was also described in the central nervous system, where its main putative endogenous ligand is N-arachidonoyl ethanolamide (an endocannabinoid, also known as anandamide). Recent results employing genetic, pharmacological and histochemical techniques indicate that TRPV1 tonically modulate anxiety, fear and panic responses in brain regions related to defensive responses, such as the dorsal periaqueductal gray, the hippocampus and the medial prefrontal cortex. Genetic deletion or antagonism of this ion channel induces anxiolytic-like effects in several animal models. The main mechanism responsible for TRPV1-mediated effects on anxiety seems to involve facilitation of glutamatergic neurotransmission. In addition, there is evidence for interactions with other neurotransmitter systems, such as nitric oxide and endocannabinoids. PMID:24726577

  3. Phα1β toxin prevents capsaicin-induced nociceptive behavior and mechanical hypersensitivity without acting on TRPV1 channels.

    PubMed

    Castro-Junior, Celio J; Milano, Julie; Souza, Alessandra H; Silva, Juliana F; Rigo, Flávia K; Dalmolin, Geruza; Cordeiro, Marta N; Richardson, Michael; Barros, Alexandre G A; Gomez, Renato S; Silva, Marco A R; Kushmerick, Christopher; Ferreira, Juliano; Gomez, Marcus V

    2013-08-01

    Phα1β toxin is a peptide purified from the venom of the armed spider Phoneutria nigriventer, with markedly antinociceptive action in models of acute and persistent pain in rats. Similarly to ziconotide, its analgesic action is related to inhibition of high voltage activated calcium channels with more selectivity for N-type. In this study we evaluated the effect of Phα1β when injected peripherally or intrathecally in a rat model of spontaneous pain induced by capsaicin. We also investigated the effect of Phα1β on Ca²⁺ transients in cultured dorsal root ganglia (DRG) neurons and HEK293 cells expressing the TRPV1 receptor. Intraplantar or intrathecal administered Phα1β reduced both nocifensive behavior and mechanical hypersensitivity induced by capsaicin similarly to that observed with SB366791, a specific TRPV1 antagonist. Peripheral nifedipine and mibefradil did also decrease nociceptive behavior induced by intraplantar capsaicin. In contrast, ω-conotoxin MVIIA (a selective N-type Ca²⁺ channel blocker) was effective only when administered intrathecally. Phα1β, MVIIA and SB366791 inhibited, with similar potency, the capsaicin-induced Ca²⁺ transients in DRG neurons. The simultaneous administration of Phα1β and SB366791 inhibited the capsaicin-induced Ca²⁺ transients that were additive suggesting that they act through different targets. Moreover, Phα1β did not inhibit capsaicin-activated currents in patch-clamp recordings of HEK293 cells that expressed TRPV1 receptors. Our results show that Phα1β may be effective as a therapeutic strategy for pain and this effect is not related to the inhibition of TRPV1 receptors. PMID:23597507

  4. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a novel activator of transient receptor potential vanilloid 1 (TRPV1) channel.

    PubMed

    Wen, Hairuo; Östman, Johan; Bubb, Kristen J; Panayiotou, Catherine; Priestley, John V; Baker, Mark D; Ahluwalia, Amrita

    2012-04-20

    TRPV1 is a member of the transient receptor potential ion channel family and is gated by capsaicin, the pungent component of chili pepper. It is expressed predominantly in small diameter peripheral nerve fibers and is activated by noxious temperatures >42 °C. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P-450 4A/4F-derived metabolite of the membrane phospholipid arachidonic acid. It is a powerful vasoconstrictor and has structural similarities with other TRPV1 agonists, e.g. the hydroperoxyeicosatetraenoic acid 12-HPETE, and we hypothesized that it may be an endogenous ligand for TRPV1 in sensory neurons innervating the vasculature. Here, we demonstrate that 20-HETE both activates and sensitizes mouse and human TRPV1, in a kinase-dependent manner, involving the residue Ser(502) in heterologously expressed hTRPV1, at physiologically relevant concentrations. PMID:22389490

  5. Characterization of A-425619 at native TRPV1 receptors: a comparison between dorsal root ganglia and trigeminal ganglia.

    PubMed

    McDonald, Heath A; Neelands, Torben R; Kort, Michael; Han, Ping; Vos, Melissa H; Faltynek, Connie R; Moreland, Robert B; Puttfarcken, Pamela S

    2008-10-31

    1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea (A-425619), a novel, potent, and selective transient receptor potential type V1 (TRPV1) antagonist, attenuates pain associated with inflammation and tissue injury in rats. The purpose of this study was to extend the in vitro characterization of A-425619 to native TRPV1 receptors and to compare the pharmacological properties of TRPV1 receptors in the dorsal root ganglion with trigeminal ganglion neurons. A robust increase in intracellular Ca(2+) was elicited by a variety of TRPV1 agonists with similar rank order of potency between both cultures: resiniferatoxin>tinyatoxin>capsaicin>N-arachidonoyl-dopamine (NADA). A-425619 blocked the 500 nM capsaicin response in both dorsal root ganglion with trigeminal ganglion cultures with IC(50) values of 78 nM and 115 nM, respectively, whereas capsazepine was significantly less potent (dorsal root ganglia: IC(50)=2.63 microM; trigeminal ganglia: IC(50)=6.31 microM). Furthermore, A-425619 was more potent in blocking the 3 microM NADA-evoked response in both dorsal root ganglia (IC(50)=36 nM) and trigeminal ganglia (IC(50)=37 nM) than capsazepine (dorsal root ganglia, IC(50)=741 nM; trigeminal ganglia, IC(50)=708 nM). Electrophysiology studies showed that 100 nM A-425619 completely inhibited TRPV1-mediated acid activated currents in dorsal root ganglia and trigeminal ganglia neurons. In addition, A-425619 blocked capsaicin- and NADA-evoked calcitonin gene-related peptide (CGRP) release in both cultures more effectively than capsazepine. These data show that A-425619 is a potent TRPV1 antagonist at the native TRPV1 receptors, and suggest that the pharmacological profile for TRPV1 receptors on dorsal root ganglia and trigeminal ganglia is very similar. PMID:18755179

  6. Structural mechanism underlying capsaicin binding and activation of TRPV1 ion channel

    PubMed Central

    Cheng, Wei; Yang, Wei; Yu, Peilin; Song, Zhenzhen; Yarov-Yarovoy, Vladimir; Zheng, Jie

    2015-01-01

    Capsaicin bestows spiciness by activating TRPV1 channel with exquisite potency and selectivity. Capsaicin-bound channel structure was previously resolved by cryo-EM at 4.2-to-4.5 Å resolution, however important details required for mechanistic understandings are unavailable: capsaicin was registered as a small electron density, reflecting neither its chemical structure nor specific ligand-channel interactions. We obtained the missing atomic-level details by iterative computation, which were confirmed by systematic site-specific functional tests. We observed that the bound capsaicin takes “tail-up, head-down” configurations. The vanillyl and amide groups form specific interactions to anchor its bound position, while the aliphatic tail may sample a range of conformations, making it invisible in cryo-EM images. Capsaicin stabilizes the open state by “pull-and-contact” interactions between the vanillyl group and the S4-S5 linker. Our study provided a structural mechanism for the agonistic function of capsaicin and its analogs, and demonstrated an effective approach to obtain atomic level information from cryo-EM structures. PMID:26053297

  7. Deletion of vanilloid receptor (TRPV1) in mice alters behavioral effects of ethanol

    PubMed Central

    Blednov, Y.A.; Harris, R.A.

    2009-01-01

    The vanilloid receptor TRPV1 is activated by ethanol and this may be important for some of the central and peripheral actions of ethanol. To determine if this receptor has a role in ethanol-mediated behaviors, we studied null mutant mice in which the Trpv1 gene was deleted. Mice lacking this gene showed significantly higher preference for ethanol and consumed more ethanol in a two-bottle choice test as compared with wild type littermates. Null mutant mice showed shorter duration of loss of righting reflex induced by low doses of ethanol (3.2 and 3.4 g/kg) and faster recovery from motor incoordination induced by ethanol (2 g/kg). However, there were no differences between null mutant and wild type mice in severity of ethanol-induced acute withdrawal (4 g/kg) or conditioned taste aversion to ethanol (2.5 g/kg). Two behavioral phenotypes (decreased sensitivity to ethanol-induced sedation and faster recovery from ethanol-induced motor incoordination) seen in null mutant mice were reproduced in wild type mice by injection of a TRPV1 antagonist, capsazepine (10 mg/kg). These two ethanol behaviors were changed in the opposite direction after injection of capsaicin, a selective TRPV1 agonist, in wild type mice. The studies provide the first evidence that TRPV1 is important for specific behavioral actions of ethanol. PMID:19705551

  8. Binding Mode Prediction of Evodiamine within Vanilloid Receptor TRPV1

    PubMed Central

    Wang, Zhanli; Sun, Lidan; Yu, Hui; Zhang, Yanhui; Gong, Wuzhuang; Jin, Hongwei; Zhang, Liangren; Liang, Huaping

    2012-01-01

    Accurate assessment of the potential binding mode of drugs is crucial to computer-aided drug design paradigms. It has been reported that evodiamine acts as an agonist of the vanilloid receptor Transient receptor potential vanilloid-1 (TRPV1). However, the precise interaction between evodiamine and TRPV1 was still not fully understood. In this perspective, the homology models of TRPV1 were generated using the crystal structure of the voltage-dependent shaker family K+ channel as a template. We then performed docking and molecular dynamics simulation to gain a better understanding of the probable binding modes of evodiamine within the TRPV1 binding pocket. There are no significant interspecies differences in evodiamine binding in rat, human and rabbit TRPV1 models. Pharmacophore modeling further provided confidence for the validity of the docking studies. This study is the first to shed light on the structural determinants required for the interaction between TRPV1 and evodiamine, and gives new suggestions for the rational design of novel TRPV1 ligands. PMID:22942745

  9. Gingerol Reverses the Cancer-Promoting Effect of Capsaicin by Increased TRPV1 Level in a Urethane-Induced Lung Carcinogenic Model.

    PubMed

    Geng, Shengnan; Zheng, Yaqiu; Meng, Mingjing; Guo, Zhenzhen; Cao, Ning; Ma, Xiaofang; Du, Zhenhua; Li, Jiahuan; Duan, Yongjian; Du, Gangjun

    2016-08-10

    Both gingerol and capsaicin are agonists of TRPV1, which can negatively control tumor progression. This study observed the long-term effects of oral administration of 6-gingerol alone or in combination with capsaicin for 20 weeks in a urethane-induced lung carcinogenic model. We showed that lung carcinoma incidence and multiplicity were 70% and 21.2 ± 3.6, respectively, in the control versus 100% and 35.6 ± 5.2 in the capsaicin group (P < 0.01) and 50% and 10.8 ± 3.1 in the 6-gingerol group (P < 0.01). The combination of 6-gingerol and capsaicin reversed the cancer-promoting effect of capsaicin (carcinoma incidence of 100% versus 20% and multiplicity of 35.6 ± 5.2 versus 4.7 ± 2.3; P < 0.001). The cancer-promoting effect of capsaicin was due to increased epidermal growth-factor receptor (EGFR) level by decreased transient receptor potential vanilloid type-1 (TRPV1) level (P < 0.01) . The capsaicin-decreased EGFR level subsequently reduced levels of nuclear factor-κB (NF-κB) and cyclin D1 that favored enhanced lung epithelial proliferation and epithelial-mesenchymal transition (EMT) during lung carcinogenesis (P < 0.01). In contrast, 6-gingerol promoted TRPV1 level and drastically decreased the levels of EGFR, NF-κB, and cyclin D1 that favored reduced lung epithelial proliferation and EMT (P < 0.01). This study provides valuable information for the long-term consumption of chili-pepper-rich diets to decrease the risk of cancer development. PMID:27436516

  10. TRPV1 and PLC Participate in Histamine H4 Receptor-Induced Itch

    PubMed Central

    Jian, Tunyu; Yang, Niuniu; Yang, Yan; Zhu, Chan; Yuan, Xiaolin; Yu, Guang; Wang, Changming; Wang, Zhongli; Shi, Hao; Tang, Min; He, Qian; Lan, Lei; Wu, Guanyi; Tang, Zongxiang

    2016-01-01

    Histamine H4 receptor has been confirmed to play a role in evoking peripheral pruritus. However, the ionic and intracellular signaling mechanism of activation of H4 receptor on the dorsal root ganglion (DRG) neurons is still unknown. By using cell culture and calcium imaging, we studied the underlying mechanism of activation of H4 receptor on the DRG neuron. Immepip dihydrobromide (immepip)—a histamine H4 receptor special agonist under cutaneous injection—obviously induced itch behavior of mice. Immepip-induced scratching behavior could be blocked by TRPV1 antagonist AMG9810 and PLC pathway inhibitor U73122. Application of immepip (8.3–50 μM) could also induce a dose-dependent increase in intracellular Ca2+ ([Ca2+]i) of DRG neurons. We found that 77.8% of the immepip-sensitized DRG neurons respond to the TRPV1 selective agonist capsaicin. U73122 could inhibit immepip-induced Ca2+ responses. In addition, immepip-induced [Ca2+]i increase could be blocked by ruthenium red, capsazepine, and AMG9810; however it could not be blocked by TRPA1 antagonist HC-030031. These results indicate that TRPV1 but not TRPA1 is the important ion channel to induce the DRG neurons' responses in the downstream signaling pathway of histamine H4 receptor and suggest that TRPV1 may be involved in the mechanism of histamine-induced itch response by H4 receptor activation. PMID:26819760

  11. TRPV1 and PLC Participate in Histamine H4 Receptor-Induced Itch.

    PubMed

    Jian, Tunyu; Yang, Niuniu; Yang, Yan; Zhu, Chan; Yuan, Xiaolin; Yu, Guang; Wang, Changming; Wang, Zhongli; Shi, Hao; Tang, Min; He, Qian; Lan, Lei; Wu, Guanyi; Tang, Zongxiang

    2016-01-01

    Histamine H4 receptor has been confirmed to play a role in evoking peripheral pruritus. However, the ionic and intracellular signaling mechanism of activation of H4 receptor on the dorsal root ganglion (DRG) neurons is still unknown. By using cell culture and calcium imaging, we studied the underlying mechanism of activation of H4 receptor on the DRG neuron. Immepip dihydrobromide (immepip)-a histamine H4 receptor special agonist under cutaneous injection-obviously induced itch behavior of mice. Immepip-induced scratching behavior could be blocked by TRPV1 antagonist AMG9810 and PLC pathway inhibitor U73122. Application of immepip (8.3-50 μM) could also induce a dose-dependent increase in intracellular Ca(2+) ([Ca(2+)]i) of DRG neurons. We found that 77.8% of the immepip-sensitized DRG neurons respond to the TRPV1 selective agonist capsaicin. U73122 could inhibit immepip-induced Ca(2+) responses. In addition, immepip-induced [Ca(2+)]i increase could be blocked by ruthenium red, capsazepine, and AMG9810; however it could not be blocked by TRPA1 antagonist HC-030031. These results indicate that TRPV1 but not TRPA1 is the important ion channel to induce the DRG neurons' responses in the downstream signaling pathway of histamine H4 receptor and suggest that TRPV1 may be involved in the mechanism of histamine-induced itch response by H4 receptor activation. PMID:26819760

  12. Targeting the Transient Receptor Potential Vanilloid Type 1 (TRPV1) Assembly Domain Attenuates Inflammation-induced Hypersensitivity*

    PubMed Central

    Flynn, Robyn; Chapman, Kevin; Iftinca, Mircea; Aboushousha, Reem; Varela, Diego; Altier, Christophe

    2014-01-01

    The transient receptor potential channel vanilloid type 1 (TRPV1) is a non-selective cation channel expressed in sensory neurons of the dorsal root and trigeminal ganglia. TRPV1 is a polymodal channel activated by noxious heat, capsaicin, and protons. As a sensor for noxious stimuli, TRPV1 channel has been described as a key contributor to pain signaling. To form a functional channel, TRPV1 subunits must assemble into tetramers, and several studies have identified the TRPV1 C terminus as an essential element in subunit association. Here we combined biochemical assays with electrophysiology and imaging-based bimolecular fluorescence complementation (BiFC) and bioluminescence resonance energy transfer (BRET) in live cells to identify a short motif in the C-terminal tail of the TRPV1 subunit that governs channel assembly. Removing this region through early truncation or targeted deletion results in loss of subunit association and channel function. Importantly, we found that interfering with TRPV1 subunit association using a plasma membrane-tethered peptide attenuated mechanical and thermal hypersensitivity in two mouse models of inflammatory hyperalgesia. This represents a novel mechanism to disrupt TRPV1 subunit assembly and hence may offer a new analgesic tool for pain relief. PMID:24808184

  13. Targeting the transient receptor potential vanilloid type 1 (TRPV1) assembly domain attenuates inflammation-induced hypersensitivity.

    PubMed

    Flynn, Robyn; Chapman, Kevin; Iftinca, Mircea; Aboushousha, Reem; Varela, Diego; Altier, Christophe

    2014-06-13

    The transient receptor potential channel vanilloid type 1 (TRPV1) is a non-selective cation channel expressed in sensory neurons of the dorsal root and trigeminal ganglia. TRPV1 is a polymodal channel activated by noxious heat, capsaicin, and protons. As a sensor for noxious stimuli, TRPV1 channel has been described as a key contributor to pain signaling. To form a functional channel, TRPV1 subunits must assemble into tetramers, and several studies have identified the TRPV1 C terminus as an essential element in subunit association. Here we combined biochemical assays with electrophysiology and imaging-based bimolecular fluorescence complementation (BiFC) and bioluminescence resonance energy transfer (BRET) in live cells to identify a short motif in the C-terminal tail of the TRPV1 subunit that governs channel assembly. Removing this region through early truncation or targeted deletion results in loss of subunit association and channel function. Importantly, we found that interfering with TRPV1 subunit association using a plasma membrane-tethered peptide attenuated mechanical and thermal hypersensitivity in two mouse models of inflammatory hyperalgesia. This represents a novel mechanism to disrupt TRPV1 subunit assembly and hence may offer a new analgesic tool for pain relief. PMID:24808184

  14. TRPV1 receptors mediate particulate matter-induced apoptosis.

    PubMed

    Agopyan, N; Head, J; Yu, S; Simon, S A

    2004-03-01

    Exposure to airborne particulate matter (PM) is a world-wide health problem mainly because it produces adverse cardiovascular and respiratory effects that frequently result in morbidity. Despite many years of epidemiological and basic research, the mechanisms underlying PM toxicity remain largely unknown. To understand some of these mechanisms, we measured PM-induced apoptosis and necrosis in normal human airway epithelial cells and sensory neurons from both wild-type mice and mice lacking TRPV1 receptors using Alexa Fluor 488-conjugated annexin V and propidium iodide labeling, respectively. Exposure of environmental PMs containing residual oil fly ash and ash from Mount St. Helens was found to induce apoptosis, but not necrosis, as a consequence of sustained calcium influx through TRPV1 receptors. Apoptosis was completely prevented by inhibiting TRPV1 receptors with capsazepine or by removing extracellular calcium or in sensory neurons from TRPV1(-/-) mice. Binding of either one of the PMs to the cell membrane induced a capsazepine-sensitive increase in cAMP. PM-induced apoptosis was augmented upon the inhibition of PKA. PKA inhibition on its own also induced apoptosis, thereby suggesting that this pathway may be endogenously protective against apoptosis. In summary, it was found that inhibiting TRPV1 receptors prevents PM-induced apoptosis, thereby providing a potential mechanism to reduce their toxicity. PMID:14633515

  15. Biological activity of a polypeptide modulator of TRPV1 receptor.

    PubMed

    Dyachenko, I A; Andreev, Ya A; Logashina, Yu A; Murashev, A N; Grishin, E V

    2015-11-01

    This paper presents data on the activity of a new APHC2 polypeptide modulator of TRPV1 receptors, which was isolated from the sea anemone Heteractis crispa. It has been shown that APHC2 has an analgesic activity, does not impair normal motor activity, and does not change body temperature of experimental animals, which has a great practical value for design of potent analgesics of a new generation. Further study of the characteristics of binding of the polypeptide to the TRPV1 receptor may show approaches to the development of other antagonists of this receptor that do not influence the body temperature. PMID:26725234

  16. TRPV1 receptors augment basal synaptic transmission in CA1 and CA3 pyramidal neurons in epilepsy.

    PubMed

    Saffarzadeh, F; Eslamizade, M J; Mousavi, S M M; Abraki, S B; Hadjighassem, M R; Gorji, A

    2016-02-01

    Temporal lobe epilepsy in human and animals is attributed to alterations in brain function especially hippocampus formation. Changes in synaptic activity might be causally related to the alterations during epileptogenesis. Transient receptor potential vanilloid 1 (TRPV1) as one of the non-selective ion channels has been shown to be involved in synaptic transmission. However, the potential role of TRPV1 receptors in synaptic function in the epileptic brain needs to be elucidated. In the present study, we used quantitative real-time PCR (qRT-PCR), western blotting, and immunohistochemistry to assess hippocampal TRPV1 mRNA expression, protein content, and distribution. Moreover, the effects of pharmacologic activation and inhibition of TRPV1 receptors on the slope of evoked field excitatory postsynaptic potentials (fEPSPs) were analyzed in CA1 and CA3 pyramidal neurons, after 3months of pilocarpine-induced status epilepticus (SE). SE induced an upregulation of TRPV1 mRNA and protein content in the whole hippocampal extract, as well as its distribution in both CA1 and CA3 regions. Activation and inhibition of TRPV1 receptors (via capsaicin 1μM and capsazepine 10μM, respectively) did not influence basal synaptic transmission in CA1 and CA3 regions of control slices, however, capsaicin increased and capsazepine decreased synaptic transmission in both regions in tissues from epileptic animals. Taken together, these findings suggest that a higher expression of TRPV1 in the epileptic condition is accompanied by alterations in basal synaptic transmission. PMID:26621124

  17. AMG 9810 [(E)-3-(4-t-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4] dioxin-6-yl)acrylamide], a novel vanilloid receptor 1 (TRPV1) antagonist with antihyperalgesic properties.

    PubMed

    Gavva, Narender R; Tamir, Rami; Qu, Yusheng; Klionsky, Lana; Zhang, T J; Immke, David; Wang, Judy; Zhu, Dawn; Vanderah, Todd W; Porreca, Frank; Doherty, Elizabeth M; Norman, Mark H; Wild, Kenneth D; Bannon, Anthony W; Louis, Jean-Claude; Treanor, James J S

    2005-04-01

    The vanilloid receptor 1 (VR1 or TRPV1) is a membrane-bound, nonselective cation channel expressed by peripheral sensory neurons. TRPV1 antagonists produce antihyperalgesic effects in animal models of inflammatory and neuropathic pain. Here, we describe the in vitro and in vivo pharmacology of a novel TRPV1 antagonist, AMG 9810, (E)-3-(4-t-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide. AMG 9810 is a competitive antagonist of capsaicin activation (IC50 value for human TRPV1, 24.5 +/- 15.7 nM; rat TRPV1, 85.6 +/- 39.4 nM) and blocks all known modes of TRPV1 activation, including protons (IC50 value for rat TRPV1, 294 +/- 192 nM; human TRPV1, 92.7 +/- 72.8 nM), heat (IC50 value for rat TRPV1, 21 +/- 17 nM; human TRPV1, 15.8 +/- 10.8 nM), and endogenous ligands, such as anandamide, N-arachidonyl dopamine, and oleoyldopamine. AMG 9810 blocks capsaicin-evoked depolarization and calcitonin gene-related peptide release in cultures of rat dorsal root ganglion primary neurons. Screening of AMG 9810 against a panel of G protein-coupled receptors and ion channels indicated selectivity toward TRPV1. In vivo, AMG 9810 is effective at preventing capsaicin-induced eye wiping in a dose-dependent manner, and it reverses thermal and mechanical hyperalgesia in a model of inflammatory pain induced by intraplantar injection of complete Freund's adjuvant. At effective doses, AMG 9810 did not show any significant effects on motor function, as measured by open field locomotor activity and motor coordination tests. AMG 9810 is the first cinnamide TRPV1 antagonist reported to block capsaicin-induced eye wiping behavior and reverse hyperalgesia in an animal model of inflammatory pain. PMID:15615864

  18. Pharmacology of the capsaicin receptor, transient receptor potential vanilloid type-1 ion channel.

    PubMed

    Nagy, Istvan; Friston, Dominic; Valente, Jojo Sousa; Torres Perez, Jose Vicente; Andreou, Anna P

    2014-01-01

    The capsaicin receptor, transient receptor potential vanilloid type 1 ion channel (TRPV1), has been identified as a polymodal transducer molecule on a sub-set of primary sensory neurons which responds to various stimuli including noxious heat (> -42 degrees C), protons and vanilloids such as capsaicin, the hot ingredient of chilli peppers. Subsequently, TRPV1 has been found indispensable for the development of burning pain and reflex hyperactivity associated with inflammation of peripheral tissues and viscera, respectively. Therefore, TRPV1 is regarded as a major target for the development of novel agents for the control of pain and visceral hyperreflexia in inflammatory conditions. Initial efforts to introduce agents acting on TRPV1 into clinics have been hampered by unexpected side-effects due to wider than expected expression in various tissues, as well as by the complex pharmacology, of TRPV1. However, it is believed that better understanding of the pharmacological properties of TRPV1 and specific targeting of tissues may eventually lead to the development of clinically useful agents. In order to assist better understanding of TRPV1 pharmacology, here we are giving a comprehensive account on the activation and inactivation mechanisms and the structure-function relationship of TRPV1. PMID:24941664

  19. Activation of recombinant human TRPV1 receptors expressed in SH-SY5Y human neuroblastoma cells increases [Ca(2+)](i), initiates neurotransmitter release and promotes delayed cell death.

    PubMed

    Lam, Patricia M W; Hainsworth, Atticus H; Smith, Graham D; Owen, Davina E; Davies, James; Lambert, David G

    2007-08-01

    The transient receptor potential (TRP) vanilloid receptor subtype 1 (TRPV1) is a ligand-gated, Ca(2+)-permeable ion channel in the TRP superfamily of channels. We report the establishment of the first neuronal model expressing recombinant human TRPV1 (SH-SY5Y(hTRPV1)). SH-SY5Y human neuroblastoma cells were stably transfected with hTRPV1 using the Amaxa Biosystem (hTRPV1 in pIREShyg2 with hygromycin selection). Capsaicin, olvanil, resiniferatoxin and the endocannabinoid anandamide increased [Ca(2+)](i) with potency (EC(50)) values of 2.9 nmol/L, 34.7 nmol/L, 0.9 nmol/L and 4.6 micromol/L, respectively. The putative endovanilloid N-arachidonoyl-dopamine increased [Ca(2+)](i) but this response did not reach a maximum. Capsaicin, anandamide, resiniferatoxin and olvanil mediated increases in [Ca(2+)](i) were inhibited by the TRPV1 antagonists capsazepine and iodo-resiniferatoxin with potencies (K(B)) of approximately 70 nmol/L and 2 nmol/L, respectively. Capsaicin stimulated the release of pre-labelled [(3)H]noradrenaline from monolayers of SH-SY5Y(hTRPV1) cells with an EC(50) of 0.6 nmol/L indicating amplification between [Ca(2+)](i) and release. In a perfusion system, we simultaneously measured [(3)H]noradrenaline release and [Ca(2+)](i) and observed that increased [Ca(2+)](i) preceded transmitter release. Capsaicin treatment also produced a cytotoxic response (EC(50) 155 nmol/L) that was antagonist-sensitive and mirrored the [Ca(2+)](I) response. This model displays pharmacology consistent with TRPV1 heterologously expressed in standard non-neuronal cells and native neuronal cultures. The advantage of SH-SY5Y(hTRPV1) is the ability of hTRPV1 to couple to neuronal biochemical machinery and produce large quantities of cells. PMID:17442052

  20. Epithelial TRPV1 signaling accelerates gingival epithelial cell proliferation.

    PubMed

    Takahashi, N; Matsuda, Y; Yamada, H; Tabeta, K; Nakajima, T; Murakami, S; Yamazaki, K

    2014-11-01

    Transient receptor potential cation channel subfamily V member 1 (TRPV1), a member of the calcium-permeable thermosensitive transient receptor potential superfamily, is a sensor of thermal and chemical stimuli. TRPV1 is activated by noxious heat (> 43°C), acidic conditions (pH < 6.6), capsaicin, and endovanilloids. This pain receptor was discovered on nociceptive fibers in the peripheral nervous system. TRPV1 was recently found to be expressed by non-neuronal cells, such as epithelial cells. The oral gingival epithelium is exposed to multiple noxious stimuli, including heat and acids derived from endogenous and exogenous substances; however, whether gingival epithelial cells (GECs) express TRPV1 is unknown. We show that both TRPV1 mRNA and protein are expressed by GECs. Capsaicin, a TRPV1 agonist, elevated intracellular Ca(2+) levels in the gingival epithelial cell line, epi 4. Moreover, TRPV1 activation in epi 4 cells accelerated proliferation. These responses to capsaicin were inhibited by a specific TRPV1 antagonist, SB-366791. We also observed GEC proliferation in capsaicin-treated mice in vivo. No effects were observed on GEC apoptosis by epithelial TRPV1 signaling. To examine the molecular mechanisms underlying this proliferative effect, we performed complementary (c)DNA microarray analysis of capsaicin-stimulated epi 4 cells. Compared with control conditions, 227 genes were up-regulated and 232 genes were down-regulated following capsaicin stimulation. Several proliferation-related genes were validated by independent experiments. Among them, fibroblast growth factor-17 and neuregulin 2 were significantly up-regulated in capsaicin-treated epi 4 cells. Our results suggest that functional TRPV1 is expressed by GECs and contributes to the regulation of cell proliferation. PMID:25266715

  1. Analgesic Compound from Sea Anemone Heteractis crispa Is the First Polypeptide Inhibitor of Vanilloid Receptor 1 (TRPV1)*

    PubMed Central

    Andreev, Yaroslav A.; Kozlov, Sergey A.; Koshelev, Sergey G.; Ivanova, Ekaterina A.; Monastyrnaya, Margarita M.; Kozlovskaya, Emma P.; Grishin, Eugene V.

    2008-01-01

    Venomous animals from distinct phyla such as spiders, scorpions, snakes, cone snails, or sea anemones produce small toxic proteins interacting with a variety of cell targets. Their bites often cause pain. One of the ways of pain generation is the activation of TRPV1 channels. Screening of 30 different venoms from spiders and sea anemones for modulation of TRPV1 activity revealed inhibitors in tropical sea anemone Heteractis crispa venom. Several separation steps resulted in isolation of an inhibiting compound. This is a 56-residue-long polypeptide named APHC1 that has a Bos taurus trypsin inhibitor (BPTI)/Kunitz-type fold, mostly represented by serine protease inhibitors and ion channel blockers. APHC1 acted as a partial antagonist of capsaicin-induced currents (32 ± 9% inhibition) with half-maximal effective concentration (EC50) 54 ± 4 nm. In vivo, a 0.1 mg/kg dose of APHC1 significantly prolonged tail-flick latency and reduced capsaicin-induced acute pain. Therefore, our results can make an important contribution to the research into molecular mechanisms of TRPV1 modulation and help to solve the problem of overactivity of this receptor during a number of pathological processes in the organism. PMID:18579526

  2. The role of endogenous molecules in modulating pain through transient receptor potential vanilloid 1 (TRPV1)

    PubMed Central

    Morales-Lázaro, Sara L; Simon, Sidney A; Rosenbaum, Tamara

    2013-01-01

    Pain is a physiological response to a noxious stimulus that decreases the quality of life of those sufferring from it. Research aimed at finding new therapeutic targets for the treatment of several maladies, including pain, has led to the discovery of numerous molecular regulators of ion channels in primary afferent nociceptive neurons. Among these receptors is TRPV1 (transient receptor potential vanilloid 1), a member of the TRP family of ion channels. TRPV1 is a calcium-permeable channel, which is activated or modulated by diverse exogenous noxious stimuli such as high temperatures, changes in pH, and irritant and pungent compounds, and by selected molecules released during tissue damage and inflammatory processes. During the last decade the number of endogenous regulators of TRPV1's activity has increased to include lipids that can negatively regulate TRPV1, as is the case for cholesterol and PIP2 (phosphatidylinositol 4,5-biphosphate) while, in contrast, other lipids produced in response to tissue injury and ischaemic processes are known to positively regulate TRPV1. Among the latter, lysophosphatidic acid activates TRPV1 while amines such as N-acyl-ethanolamines and N-acyl-dopamines can sensitize or directly activate TRPV1. It has also been found that nucleotides such as ATP act as mediators of chemically induced nociception and pain and gases, such as hydrogen sulphide and nitric oxide, lead to TRPV1 activation. Finally, the products of lipoxygenases and omega-3 fatty acids among other molecules, such as divalent cations, have also been shown to endogenously regulate TRPV1 activity. Here we provide a comprehensive review of endogenous small molecules that regulate the function of TRPV1. Acting through mechanisms that lead to sensitization and desensitization of TRPV1, these molecules regulate pathways involved in pain and nociception. Understanding how these compounds modify TRPV1 activity will allow us to comprehend how some pathologies are associated with

  3. Detailed Analysis of the Binding Mode of Vanilloids to Transient Receptor Potential Vanilloid Type I (TRPV1) by a Mutational and Computational Study.

    PubMed

    Ohbuchi, Katsuya; Mori, Yoshikazu; Ogawa, Kazuo; Warabi, Eiji; Yamamoto, Masahiro; Hirokawa, Takatsugu

    2016-01-01

    Transient receptor potential vanilloid type 1 (TRPV1) is a non-selective cation channel and a multimodal sensor protein. Since the precise structure of TRPV1 was obtained by electron cryo-microscopy, the binding mode of representative agonists such as capsaicin and resiniferatoxin (RTX) has been extensively characterized; however, detailed information on the binding mode of other vanilloids remains lacking. In this study, mutational analysis of human TRPV1 was performed, and four agonists (capsaicin, RTX, [6]-shogaol and [6]-gingerol) were used to identify amino acid residues involved in ligand binding and/or modulation of proton sensitivity. The detailed binding mode of each ligand was then simulated by computational analysis. As a result, three amino acids (L518, F591 and L670) were newly identified as being involved in ligand binding and/or modulation of proton sensitivity. In addition, in silico docking simulation and a subsequent mutational study suggested that [6]-gingerol might bind to and activate TRPV1 in a unique manner. These results provide novel insights into the binding mode of various vanilloids to the channel and will be helpful in developing a TRPV1 modulator. PMID:27606946

  4. Long-Term Activation of Group I Metabotropic Glutamate Receptors Increases Functional TRPV1-Expressing Neurons in Mouse Dorsal Root Ganglia.

    PubMed

    Masuoka, Takayoshi; Kudo, Makiko; Yoshida, Junko; Ishibashi, Takaharu; Muramatsu, Ikunobu; Kato, Nobuo; Imaizumi, Noriko; Nishio, Matomo

    2016-01-01

    Damaged tissues release glutamate and other chemical mediators for several hours. These chemical mediators contribute to modulation of pruritus and pain. Herein, we investigated the effects of long-term activation of excitatory glutamate receptors on functional expression of transient receptor potential vaniloid type 1 (TRPV1) in dorsal root ganglion (DRG) neurons and then on thermal pain behavior. In order to detect the TRPV1-mediated responses in cultured DRG neurons, we monitored intracellular calcium responses to capsaicin, a TRPV1 agonist, with Fura-2. Long-term (4 h) treatment with glutamate receptor agonists (glutamate, quisqualate or DHPG) increased the proportion of neurons responding to capsaicin through activation of metabotropic glutamate receptor mGluR1, and only partially through the activation of mGluR5; engagement of these receptors was evident in neurons responding to allylisothiocyanate (AITC), a transient receptor potential ankyrin type 1 (TRPA1) agonist. Increase in the proportion was suppressed by phospholipase C (PLC), protein kinase C, mitogen/extracellular signal-regulated kinase, p38 mitogen-activated protein kinase or transcription inhibitors. Whole-cell recording was performed to record TRPV1-mediated membrane current; TRPV1 current density significantly increased in the AITC-sensitive neurons after the quisqualate treatment. To elucidate the physiological significance of this phenomenon, a hot plate test was performed. Intraplantar injection of quisqualate or DHPG induced heat hyperalgesia that lasted for 4 h post injection. This chronic hyperalgesia was attenuated by treatment with either mGluR1 or mGluR5 antagonists. These results suggest that long-term activation of mGluR1/5 by peripherally released glutamate may increase the number of neurons expressing functional TRPV1 in DRG, which may be strongly associated with chronic hyperalgesia. PMID:27064319

  5. Long-Term Activation of Group I Metabotropic Glutamate Receptors Increases Functional TRPV1-Expressing Neurons in Mouse Dorsal Root Ganglia

    PubMed Central

    Masuoka, Takayoshi; Kudo, Makiko; Yoshida, Junko; Ishibashi, Takaharu; Muramatsu, Ikunobu; Kato, Nobuo; Imaizumi, Noriko; Nishio, Matomo

    2016-01-01

    Damaged tissues release glutamate and other chemical mediators for several hours. These chemical mediators contribute to modulation of pruritus and pain. Herein, we investigated the effects of long-term activation of excitatory glutamate receptors on functional expression of transient receptor potential vaniloid type 1 (TRPV1) in dorsal root ganglion (DRG) neurons and then on thermal pain behavior. In order to detect the TRPV1-mediated responses in cultured DRG neurons, we monitored intracellular calcium responses to capsaicin, a TRPV1 agonist, with Fura-2. Long-term (4 h) treatment with glutamate receptor agonists (glutamate, quisqualate or DHPG) increased the proportion of neurons responding to capsaicin through activation of metabotropic glutamate receptor mGluR1, and only partially through the activation of mGluR5; engagement of these receptors was evident in neurons responding to allylisothiocyanate (AITC), a transient receptor potential ankyrin type 1 (TRPA1) agonist. Increase in the proportion was suppressed by phospholipase C (PLC), protein kinase C, mitogen/extracellular signal-regulated kinase, p38 mitogen-activated protein kinase or transcription inhibitors. Whole-cell recording was performed to record TRPV1-mediated membrane current; TRPV1 current density significantly increased in the AITC-sensitive neurons after the quisqualate treatment. To elucidate the physiological significance of this phenomenon, a hot plate test was performed. Intraplantar injection of quisqualate or DHPG induced heat hyperalgesia that lasted for 4 h post injection. This chronic hyperalgesia was attenuated by treatment with either mGluR1 or mGluR5 antagonists. These results suggest that long-term activation of mGluR1/5 by peripherally released glutamate may increase the number of neurons expressing functional TRPV1 in DRG, which may be strongly associated with chronic hyperalgesia. PMID:27064319

  6. Pharmacological blockade of the vanilloid receptor TRPV1 elicits marked hyperthermia in humans.

    PubMed

    Gavva, Narender R; Treanor, James J S; Garami, Andras; Fang, Liang; Surapaneni, Sekhar; Akrami, Anna; Alvarez, Francisco; Bak, Annette; Darling, Mary; Gore, Anu; Jang, Graham R; Kesslak, James P; Ni, Liyun; Norman, Mark H; Palluconi, Gabrielle; Rose, Mark J; Salfi, Margaret; Tan, Edward; Romanovsky, Andrej A; Banfield, Christopher; Davar, Gudarz

    2008-05-01

    The vanilloid receptor TRPV1 has been identified as a molecular target for the treatment of pain associated with inflammatory diseases and cancer. Hence, TRPV1 antagonists have been considered for therapeutic evaluation in such diseases. During Phase I clinical trials with AMG 517, a highly selective TRPV1 antagonist, we found that TRPV1 blockade elicited marked, but reversible, and generally plasma concentration-dependent hyperthermia. Similar to what was observed in rats, dogs, and monkeys, hyperthermia was attenuated after repeated dosing of AMG 517 (at the highest dose tested) in humans during a second Phase I trial. However, AMG 517 administered after molar extraction (a surgical cause of acute pain) elicited long-lasting hyperthermia with maximal body temperature surpassing 40 degrees C, suggesting that TRPV1 blockade elicits undesirable hyperthermia in susceptible individuals. Mechanisms of AMG 517-induced hyperthermia were then studied in rats. AMG 517 caused hyperthermia by inducing tail skin vasoconstriction and increasing thermogenesis, which suggests that TRPV1 regulates vasomotor tone and metabolic heat production. In conclusion, these results demonstrate that: (a) TRPV1-selective antagonists like AMG 517 cannot be developed for systemic use as stand alone agents for treatment of pain and other diseases, (b) individual susceptibility influences magnitude of hyperthermia observed after TRPV1 blockade, and (c) TRPV1 plays a pivotal role as a molecular regulator for body temperature in humans. PMID:18337008

  7. Whirlin increases TRPV1 channel expression and cellular stability.

    PubMed

    Ciardo, Maria Grazia; Andrés-Bordería, Amparo; Cuesta, Natalia; Valente, Pierluigi; Camprubí-Robles, María; Yang, Jun; Planells-Cases, Rosa; Ferrer-Montiel, Antonio

    2016-01-01

    The expression and function of TRPV1 are influenced by its interaction with cellular proteins. Here, we identify Whirlin, a cytoskeletal PDZ-scaffold protein implicated in hearing, vision and mechanosensory transduction, as an interacting partner of TRPV1. Whirlin associates with TRPV1 in cell lines and in primary cultures of rat nociceptors. Whirlin is expressed in 55% of mouse sensory C-fibers, including peptidergic and non-peptidergic nociceptors, and co-localizes with TRPV1 in 70% of them. Heterologous expression of Whirlin increased TRPV1 protein expression and trafficking to the plasma membrane, and promoted receptor clustering. Silencing Whirlin expression with siRNA or blocking protein translation resulted in a concomitant degradation of TRPV1 that could be prevented by inhibiting the proteasome. The degradation kinetics of TRPV1 upon arresting protein translation mirrored that of Whirlin in cells co-expressing both proteins, suggesting a parallel degradation mechanism. Noteworthy, Whirlin expression significantly reduced TRPV1 degradation induced by prolonged exposure to capsaicin. Thus, our findings indicate that Whirlin and TRPV1 are associated in a subset of nociceptors and that TRPV1 protein stability is increased through the interaction with the cytoskeletal scaffold protein. Our results suggest that the Whirlin–TRPV1 complex may represent a novel molecular target and its pharmacological disruption might be a therapeutic strategy for the treatment of peripheral TRPV1-mediated disorders. PMID:26516054

  8. THE TRPV1 RECEPTOR: TARGET OF TOXICANTS AND THERAPEUTICS

    EPA Science Inventory

    Understanding the structural and functional complexities of the TRPV1 is essential to the therapeutic modulation of inflammation and pain. Because of its central role in initiating inflammatory processes and integrating painful stimuli, there is an understandable interest...

  9. Differences in the Control of Secondary Peristalsis in the Human Esophagus: Influence of the 5-HT4 Receptor versus the TRPV1 Receptor

    PubMed Central

    Yi, Chih-Hsun; Lei, Wei-Yi; Hung, Jui-Sheng; Liu, Tso-Tsai; Orr, William C.; Fabio, Pace; Chen, Chien-Lin

    2016-01-01

    Objective Acute administration of 5-hydroxytryptamine4 (5-HT4) receptor agonist, mosapride or esophageal infusion of the transient receptor potential vanilloid receptor-1 (TRPV1) agonist capsaicin promotes secondary peristalsis. We aimed to investigate whether acute esophageal instillation of capsaicin-containing red pepper sauce or administration of mosapride has different effects on the physiological characteristics of secondary peristalsis. Methods Secondary peristalsis was induced with mid-esophageal air injections in 14 healthy subjects. We compared the effects on secondary peristalsis subsequent to capsaicin-containing red pepper sauce (pure capsaicin, 0.84 mg) or 40 mg oral mosapride. Results The threshold volume for generating secondary peristalsis during slow air distensions was significantly decreased with capsaicin infusion compared to mosapride (11.6 ± 1.0 vs. 14.1 ± 0.8 mL, P = 0.02). The threshold volume required to produce secondary peristalsis during rapid air distension was also significantly decreased with capsaicin infusion (4.6 ± 0.5 vs. 5.2 ± 0.6 mL, P = 0.02). Secondary peristalsis was noted more frequently in response to rapid air distension after capsaicin infusion than mosapride (80% [60–100%] vs. 65% [5–100%], P = 0.04). Infusion of capsaicin or mosapride administration didn’t change any parameters of primary or secondary peristalsis. Conclusions Esophageal infusion with capsaicin-containing red pepper sauce suspension does create greater mechanosensitivity as measured by secondary peristalsis than 5-HT4 receptor agonist mosapride. Capsaicin-sensitive afferents appear to be more involved in the sensory modulation of distension-induced secondary peristalsis. PMID:27438088

  10. Design and Synthesis of New Transient Receptor Potential Vanilloid Type-1 (TRPV1) Channel Modulators: Identification, Molecular Modeling Analysis, and Pharmacological Characterization of the N-(4-Hydroxy-3-methoxybenzyl)-4-(thiophen-2-yl)butanamide, a Small Molecule Endowed with Agonist TRPV1 Activity and Protective Effects against Oxidative Stress.

    PubMed

    Aiello, Francesca; Badolato, Mariateresa; Pessina, Federica; Sticozzi, Claudia; Maestrini, Vanessa; Aldinucci, Carlo; Luongo, Livio; Guida, Francesca; Ligresti, Alessia; Artese, Anna; Allarà, Marco; Costa, Giosué; Frosini, Maria; Schiano Moriello, Aniello; De Petrocellis, Luciano; Valacchi, Giuseppe; Alcaro, Stefano; Maione, Sabatino; Di Marzo, Vincenzo; Corelli, Federico; Brizzi, Antonella

    2016-06-15

    4-(Thiophen-2-yl)butanoic acid was identified as a cyclic substitute of the unsaturated alkyl chain of the natural ligand, capsaicin. Accordingly, a new class of amides was synthesized in good yield and high purity and their molecular recognition against the target was investigated by means of docking experiments followed by molecular dynamics simulations, in order to rationalize their geometrical and thermodynamic profiles. The pharmacological properties of these new compounds were expressed as activation (EC50) and desensitization (IC50) potencies. Several compounds were found to activate TRPV1 channels, and in particular, derivatives 1 and 10 behaved as TRPV1 agonists endowed with good efficacy as compared to capsaicin. The most promising compound 1 was also evaluated for its protective role against oxidative stress on keratinocytes and differentiated human neuroblastoma cell lines expressing the TRPV1 receptor as well as for its cytotoxicity and analgesic activity in vivo. PMID:26942555

  11. TRPV1 Antagonists Elevate Cell Surface Populations of Receptor Protein and Exacerbate TRPV1-Mediated Toxicities in Human Lung Epithelial Cells

    PubMed Central

    Johansen, Mark E.; Reilly, Christopher A.; Yost, Garold S.

    2008-01-01

    TRPV1 mediates cell death and pro-inflammatory cytokine production in lung epithelial cells exposed to prototypical receptor agonists. This study shows that NHBE, BEAS-2B and TRPV1 over-expressing BEAS-2B cells pre-treated with various TRPV1 antagonists become sensitized to the prototypical TRPV1 agonist, nonivamide, via a mechanism that involves translocation of existing receptor from the endoplasmic reticulum to the plasma membrane. As such, typical cellular responses to agonist treatment, as measured by calcium flux, inflammatory cytokine gene induction, and cytotoxicity were exacerbated. These data were in contrast to the results obtained when TRPV1 antagonists were co-administered with nonivamide; conditions which inhibited TRPV1-mediated effects. The antagonists LJO-328, SC0030, and capsazepine increased the cytotoxicity of nonivamide by ~20-fold and agonist-induced calcium flux by ~6-fold. Inflammatory-cytokine gene induction by nonivamide was also increased significantly by pre-treatment with the antagonists. The enhanced responses were inhibited by the co-administration of antagonists with nonivamide, confirming that increases in sensitivity were attributable to increased TRPV1-associated activity. Sensitization was attenuated by brefeldin A (a golgi transport inhibitor), but not cycloheximide (a protein synthesis inhibitor), or actinomycin D (a transcription inhibitor). Sensitized cells exhibited increased calcium flux from extracellular calcium sources, while unsensitized cells exhibited calcium flux originating primarily from intracellular stores. These results demonstrate the presence of a novel mechanism for regulating the sub-cellular distribution of TRPV1 and subsequent control of cellular sensitivity to TRPV1 agonists. PMID:16120755

  12. Artificial sweeteners and salts producing a metallic taste sensation activate TRPV1 receptors.

    PubMed

    Riera, Céline E; Vogel, Horst; Simon, Sidney A; le Coutre, Johannes

    2007-08-01

    Throughout the world many people use artificial sweeteners (AS) for the purpose of reducing caloric intake. The most prominently used of these molecules include saccharin, aspartame (Nutrasweet), acesulfame-K, and cyclamate. Despite the caloric advantage they provide, one key concern in their use is their aversive aftertaste that has been characterized on a sensory level as bitter and/or metallic. Recently, it has been shown that the activation of particular T2R bitter taste receptors is partially involved with the bitter aftertaste sensation of saccharin and acesulfame-K. To more fully understand the biology behind these phenomena we have addressed the question of whether AS could stimulate transient receptor potential vanilloid-1 (TRPV1) receptors, as these receptors are activated by a large range of structurally different chemicals. Moreover, TRPV1 receptors and/or their variants are found in taste receptor cells and in nerve terminals throughout the oral cavity. Hence, TRPV1 activation could be involved in the AS aftertaste or even contribute to the poorly understood metallic taste sensation. Using Ca(2+) imaging on TRPV1 receptors heterologously expressed in the human embryonic kidney (HEK) 293 cells and on dissociated primary sensory neurons, we find that in both systems, AS activate TRPV1 receptors, and, moreover, they sensitize these channels to acid and heat. We also found that TRPV1 receptors are activated by CuSO(4), ZnSO(4), and FeSO(4), three salts known to produce a metallic taste sensation. In summary, our results identify a novel group of compounds that activate TRPV1 and, consequently, provide a molecular mechanism that may account for off tastes of sweeteners and metallic tasting salts. PMID:17567713

  13. Molecular Cloning and Functional Characterization of Xenopus tropicalis Frog Transient Receptor Potential Vanilloid 1 Reveal Its Functional Evolution for Heat, Acid, and Capsaicin Sensitivities in Terrestrial Vertebrates*

    PubMed Central

    Ohkita, Masashi; Saito, Shigeru; Imagawa, Toshiaki; Takahashi, Kenji; Tominaga, Makoto; Ohta, Toshio

    2012-01-01

    The functional difference of thermosensitive transient receptor potential (TRP) channels in the evolutionary context has attracted attention, but thus far little information is available on the TRP vanilloid 1 (TRPV1) function of amphibians, which diverged earliest from terrestrial vertebrate lineages. In this study we cloned Xenopus tropicalis frog TRPV1 (xtTRPV1), and functional characterization was performed using HeLa cells heterologously expressing xtTRPV1 (xtTRPV1-HeLa) and dorsal root ganglion neurons isolated from X. tropicalis (xtDRG neurons) by measuring changes in the intracellular calcium concentration ([Ca2+]i). The channel activity was also observed in xtTRPV1-expressing Xenopus oocytes. Furthermore, we tested capsaicin- and heat-induced nocifensive behaviors of the frog X. tropicalis in vivo. At the amino acid level, xtTRPV1 displays ∼60% sequence identity to other terrestrial vertebrate TRPV1 orthologues. Capsaicin induced [Ca2+]i increases in xtTRPV1-HeLa and xtDRG neurons and evoked nocifensive behavior in X. tropicalis. However, its sensitivity was extremely low compared with mammalian orthologues. Low extracellular pH and heat activated xtTRPV1-HeLa and xtDRG neurons. Heat also evoked nocifensive behavior. In oocytes expressing xtTRPV1, inward currents were elicited by heat and low extracellular pH. Mutagenesis analysis revealed that two amino acids (tyrosine 523 and alanine 561) were responsible for the low sensitivity to capsaicin. Taken together, our results indicate that xtTRPV1 functions as a polymodal receptor similar to its mammalian orthologues. The present study demonstrates that TRPV1 functions as a heat- and acid-sensitive channel in the ancestor of terrestrial vertebrates. Because it is possible to examine vanilloid and heat sensitivities in vitro and in vivo, X. tropicalis could be the ideal experimental lower vertebrate animal for the study of TRPV1 function. PMID:22130664

  14. Capsaicin-induced inhibition of platelet aggregation is not mediated by transient receptor potential vanilloid type 1.

    PubMed

    Mittelstadt, Scott W; Nelson, Richard A; Daanen, Jerome F; King, Andrew J; Kort, Michael E; Kym, Philip R; Lubbers, Nathan L; Cox, Bryan F; Lynch, James J

    2012-01-01

    Capsaicin is an agonist of transient receptor potential vanilloid type 1 (TRPV1), in which it can act as a neuronal stimulant and result in nociception. Capsaicin also affects a variety of nonneuronal tissues, in which its mechanisms of action are less certain. The present study investigated whether the inhibitory effects of capsaicin on platelet aggregation are mediated via TRPV1. Venous whole blood obtained from beagle dogs (n = 6) was preincubated with capsaicin and/or the potent and selective competitive TRPV1 antagonist, A-993610 and then exposed to collagen (2 μg/ml). An aggregometer was used to quantify the platelet response. Capsaicin exposure inhibited collagen-induced platelet aggregation in a concentration-dependent manner, with significant effects at 10 and 30 μg capsaicin per millilitre. A-993610 alone (0.1-1.0 μg/ml) had no effects on collagen-induced platelet aggregation, nor did it have any effects on capsaicin's ability to inhibit platelet aggregation. The current results agree with previous findings that capsaicin can inhibit platelet aggregation. In addition, the present study demonstrates that capsaicin's inhibitory effect on collagen-induced canine platelet aggregation is not mediated by TRPV1. PMID:22089942

  15. Furanocoumarins Are a Novel Class of Modulators for the Transient Receptor Potential Vanilloid Type 1 (TRPV1) Channel*

    PubMed Central

    Chen, Xingjuan; Sun, Weiyang; Gianaris, Nicholas G.; Riley, Ashley M.; Cummins, Theodore R.; Fehrenbacher, Jill C.; Obukhov, Alexander G.

    2014-01-01

    Furanocoumarin imperatorin is the major active component of Angelica dahurica root extracts, widely used in traditional medicine to treat headache, toothache, and orbital eye pain. In this study, we investigated the mechanisms that may underlie the pain-relieving effects of the compound. We found that imperatorin significantly inhibited formalin- and capsaicin-induced nocifensive responses but did not alter baseline thermal withdrawal thresholds in the rat. We established that imperatorin is a weak agonist of TRPV1, a channel implicated in detecting several noxious stimuli, exhibiting a 50% effective concentration (EC50) of 12.6 ± 3.2 μm. A specific TRPV1 antagonist, JNJ-17203212 (0.5 μm), potently inhibited imperatorin-induced TRPV1 activation. Site-directed mutagenesis studies revealed that imperatorin most likely acted via a site adjacent to or overlapping with the TRPV1 capsaicin-binding site. TRPV1 recovery from desensitization was delayed in the presence of imperatorin. Conversely, imperatorin sensitized TRPV1 to acid activation but did not affect the current amplitude and/or the activation-inactivation properties of Nav1.7, a channel important for transmission of nociceptive information. Thus, our data indicate that furanocoumarins represent a novel group of TRPV1 modulators that may become important lead compounds in the drug discovery process aimed at developing new treatments for pain management. PMID:24569998

  16. The stress protein heat shock cognate 70 (Hsc70) inhibits the Transient Receptor Potential Vanilloid type 1 (TRPV1) channel

    PubMed Central

    Iftinca, Mircea; Flynn, Robyn; Basso, Lilian; Melo, Helvira; Aboushousha, Reem; Taylor, Lauren

    2016-01-01

    Background Specialized cellular defense mechanisms prevent damage from chemical, biological, and physical hazards. The heat shock proteins have been recognized as key chaperones that maintain cell survival against a variety of exogenous and endogenous stress signals including noxious temperature. However, the role of heat shock proteins in nociception remains poorly understood. We carried out an expression analysis of the constitutively expressed 70 kDa heat-shock cognate protein, a member of the stress-induced HSP70 family in lumbar dorsal root ganglia from a mouse model of Complete Freund’s Adjuvant-induced chronic inflammatory pain. We used immunolabeling of dorsal root ganglion neurons, behavioral analysis and patch clamp electrophysiology in both dorsal root ganglion neurons and HEK cells transfected with Hsc70 and Transient Receptor Potential Channels to examine their functional interaction in heat shock stress condition. Results We report an increase in protein levels of Hsc70 in mouse dorsal root ganglia, 3 days post Complete Freund’s Adjuvant injection in the hind paw. Immunostaining of Hsc70 was observed in most of the dorsal root ganglion neurons, including the small size nociceptors immunoreactive to the TRPV1 channel. Standard whole-cell patch-clamp technique was used to record Transient Receptor Potential Vanilloid type 1 current after exposure to heat shock. We found that capsaicin-evoked currents are inhibited by heat shock in dorsal root ganglion neurons and transfected HEK cells expressing Hsc70 and TRPV1. Blocking Hsc70 with matrine or spergualin compounds prevented heat shock-induced inhibition of the channel. We also found that, in contrast to TRPV1, both the cold sensor channels TRPA1 and TRPM8 were unresponsive to heat shock stress. Finally, we show that inhibition of TRPV1 depends on the ATPase activity of Hsc70 and involves the rho-associated protein kinase. Conclusions Our work identified Hsc70 and its ATPase activity as a central

  17. B-Type Natriuretic Peptide-Induced Delayed Modulation of TRPV1 and P2X3 Receptors of Mouse Trigeminal Sensory Neurons

    PubMed Central

    Ntamati, Niels; Nistri, Andrea

    2013-01-01

    Important pain transducers of noxious stimuli are small- and medium-diameter sensory neurons that express transient receptor vanilloid-1 (TRPV1) channels and/or adenosine triphosphate (ATP)-gated P2X3 receptors whose activity is upregulated by endogenous neuropeptides in acute and chronic pain models. Little is known about the role of endogenous modulators in restraining the expression and function of TRPV1 and P2X3 receptors. In dorsal root ganglia, evidence supports the involvement of the natriuretic peptide system in the modulation of nociceptive transmission especially via the B-type natriuretic peptide (BNP) that activates the natriuretic peptide receptor-A (NPR-A) to downregulate sensory neuron excitability. Since the role of BNP in trigeminal ganglia (TG) is unclear, we investigated the expression of BNP in mouse TG in situ or in primary cultures and its effect on P2X3 and TRPV1 receptors of patch-clamped cultured neurons. Against scant expression of BNP, almost all neurons expressed NPR-A at membrane level. While BNP rapidly increased cGMP production and Akt kinase phosphorylation, there was no early change in passive neuronal properties or responses to capsaicin, α,β-meATP or GABA. Nonetheless, 24 h application of BNP depressed TRPV1 mediated currents (an effect blocked by the NPR-A antagonist anantin) without changing responses to α,β-meATP or GABA. Anantin alone decreased basal cGMP production and enhanced control α,β-meATP-evoked responses, implying constitutive regulation of P2X3 receptors by ambient BNP. These data suggest a slow modulatory action by BNP on TRPV1 and P2X3 receptors outlining the role of this peptide as a negative regulator of trigeminal sensory neuron excitability to nociceptive stimuli. PMID:24312267

  18. Discovery of small molecule antagonists of TRPV1.

    PubMed

    Rami, Harshad K; Thompson, Mervyn; Wyman, Paul; Jerman, Jeffrey C; Egerton, Julie; Brough, Stephen; Stevens, Alexander J; Randall, Andrew D; Smart, Darren; Gunthorpe, Martin J; Davis, John B

    2004-07-16

    Small molecule antagonists of the vanilloid receptor 1 (TRPV1, also known as VR1) are disclosed. Ureas such as 5 (SB-452533) were used to explore the structure activity relationship with several potent analogues identified. Pharmacological studies using electrophysiological and FLIPR Ca(2+) based assays showed compound 5 was an antagonist versus capsaicin, noxious heat and acid mediated activation of TRPV1. Study of a quaternary salt of 5 supports a mode of action in which compounds from this series cause inhibition via an extracellularly accessible binding site on the TRPV1 receptor. PMID:15203132

  19. Cold Suppresses Agonist-induced Activation of TRPV1

    PubMed Central

    Chung, M.-K.; Wang, S.

    2011-01-01

    Cold therapy is frequently used to reduce pain and edema following acute injury or surgery such as tooth extraction. However, the neurobiological mechanisms of cold therapy are not completely understood. Transient receptor potential vanilloid 1 (TRPV1) is a capsaicin- and heat-gated nociceptive ion channel implicated in thermosensation and pathological pain under conditions of inflammation or injury. Although capsaicin-induced nociception, neuropeptide release, and ionic currents are suppressed by cold, it is not known if cold suppresses agonist-induced activation of recombinant TRPV1. We demonstrate that cold strongly suppressed the activation of recombinant TRPV1 by multiple agonists and capsaicin-evoked currents in trigeminal ganglia neurons under normal and phosphorylated conditions. Cold-induced suppression was partially impaired in a TRPV1 mutant that lacked heat-mediated activation and potentiation. These results suggest that cold-induced suppression of TRPV1 may share a common molecular basis with heat-induced potentiation, and that allosteric inhibition may contribute, in part, to the cold-induced suppression. We also show that combination of cold and a specific antagonist of TRPV1 can produce an additive suppression. Our results provide a mechanistic basis for cold therapy and may enhance anti-nociceptive approaches that target TRPV1 for managing pain under inflammation and tissue injury, including that from tooth extraction. PMID:21666106

  20. TRPV1 Activation in Primary Cortical Neurons Induces Calcium-Dependent Programmed Cell Death.

    PubMed

    Song, Juhyun; Lee, Jun Hong; Lee, Sung Ho; Park, Kyung Ah; Lee, Won Taek; Lee, Jong Eun

    2013-03-01

    Transient receptor potential cation channel, subfamily V, member 1 (TRPV1, also known as vanilloid receptor 1) is a receptor that detects capsaicin, a pungent component of chili peppers, and noxious heat. Although its function in the primary nociceptor as a pain receptor is well established, whether TRPV1 is expressed in the brain is still under debate. In this study, the responses of primary cortical neurons were investigated. Here, we report that 1) capsaicin induces caspase-3-dependent programmed cell death, which coincides with increased production of nitric oxide and peroxynitrite ; that 2) the prolonged capsaicin treatment induces a steady increase in the degree of capase-3 activation, which is prevented by the removal of capsaicin; 3) and that blocking calcium entry and calcium-mediated signaling prevents capsaicin-induced cell death. These results indicate that cortical neurons express TRPV1 whose prolonged activation causes cell death. PMID:23585723

  1. Capsaicin induces apoptosis in human small cell lung cancer via the TRPV6 receptor and the calpain pathway.

    PubMed

    Lau, Jamie K; Brown, Kathleen C; Dom, Aaron M; Witte, Theodore R; Thornhill, Brent A; Crabtree, Clayton M; Perry, Haley E; Brown, J Michael; Ball, John G; Creel, Rebecca G; Damron, C Luke; Rollyson, William D; Stevenson, Cathryn D; Hardman, W Elaine; Valentovic, Monica A; Carpenter, A Betts; Dasgupta, Piyali

    2014-08-01

    Capsaicin, the pungent ingredient of chili peppers, displays potent anti-neoplastic activity in a wide array of human cancer cells. The present manuscript examines the signaling pathways underlying the apoptotic activity of capsaicin in human small cell lung cancer (SCLC) in vitro and in vivo. Studies in neuronal cells show that capsaicin exerts its biological activity via the transient receptor potential vanilloid (TRPV) superfamily of cation-channel receptors. The TRPV family is comprised of six members (TRPV1-6). Capsaicin is a known agonist of the TRPV1 receptor. We observed that capsaicin-induced apoptosis in human SCLC cells was mediated via the TRPV receptor family; however it was independent of TRPV1. Surprisingly, the apoptotic activity of capsaicin required the TRPV6 receptor. Depletion of TRPV6 receptor by siRNA methodology abolished the apoptotic activity of capsaicin in SCLC cells. Immunostaining and ELISA showed that TRPV6 receptor was robustly expressed on human SCLC tissues (from patients) and SCLC cell lines but almost absent in normal lung tissues. This correlates with our results that capsaicin induced very little apoptosis in normal lung epithelial cells. The pro-apoptotic activity of capsaicin was mediated by the intracellular calcium and calpain pathway. The treatment of human SCLC cells with capsaicin increased the activity of calpain 1 and 2 by threefold relative to untreated SCLC cells. Such calpain activation, in response to capsaicin, was downstream of the TRPV6 receptor. Taken together, our data provide insights into the mechanism underlying the apoptotic activity of capsaicin in human SCLCs. PMID:24878626

  2. TRPV1: A Target for Rational Drug Design.

    PubMed

    Carnevale, Vincenzo; Rohacs, Tibor

    2016-01-01

    Transient Receptor Potential Vanilloid 1 (TRPV1) is a non-selective, Ca(2+) permeable cation channel activated by noxious heat, and chemical ligands, such as capsaicin and resiniferatoxin (RTX). Many compounds have been developed that either activate or inhibit TRPV1, but none of them are in routine clinical practice. This review will discuss the rationale for antagonists and agonists of TRPV1 for pain relief and other conditions, and strategies to develop new, better drugs to target this ion channel, using the newly available high-resolution structures. PMID:27563913

  3. The biophysical and molecular basis of TRPV1 proton gating

    PubMed Central

    Aneiros, Eduardo; Cao, Lishuang; Papakosta, Marianthi; Stevens, Edward B; Phillips, Stephen; Grimm, Christian

    2011-01-01

    The capsaicin receptor TRPV1, a member of the transient receptor potential family of non-selective cation channels is a polymodal nociceptor. Noxious thermal stimuli, protons, and the alkaloid irritant capsaicin open the channel. The mechanisms of heat and capsaicin activation have been linked to voltage-dependent gating in TRPV1. However, until now it was unclear whether proton activation or potentiation or both are linked to a similar voltage-dependent mechanism and which molecular determinants underlie the proton gating. Using the whole-cell patch-clamp technique, we show that protons activate and potentiate TRPV1 by shifting the voltage dependence of the activation curves towards more physiological membrane potentials. We further identified a key residue within the pore region of TRPV1, F660, to be critical for voltage-dependent proton activation and potentiation. We conclude that proton activation and potentiation of TRPV1 are both voltage dependent and that amino acid 660 is essential for proton-mediated gating of TRPV1. PMID:21285946

  4. Sumatriptan Inhibits TRPV1 Channels in Trigeminal Neurons

    PubMed Central

    Evans, M. Steven; Cheng, Xiangying; Jeffry, Joseph A.; Disney, Kimberly E.; Premkumar, Louis S.

    2011-01-01

    Objective To understand a possible role for transient potential receptor vanilloid 1 (TRPV1) ion channels in sumatriptan relief of pain mediated by trigeminal nociceptors. Background TRPV1 channels are expressed in small nociceptive sensory neurons. In dorsal root ganglia (DRG), TRPV1-containing nociceptors mediate certain types of inflammatory pain. Neurogenic inflammation of cerebral dura and blood vessels in the trigeminal nociceptive system is thought to be important in migraine pain, but the ion channels important in transducing migraine pain are not known. Sumatriptan is an agent effective in treatment of migraine and cluster headache. We hypothesized that sumatriptan might modulate activity of TRPV1 channels found in the trigeminal nociceptive system. Methods We used immunohistochemistry to detect the presence of TRPV1 channel protein, whole cell recording in acutely dissociated trigeminal ganglia (TG) to detect functionality of TRPV1 channels, and whole cell recording in trigeminal nucleus caudalis (TNC) to detect effects on release of neurotransmitters from trigeminal neurons onto second order sensory neurons. Effects specifically on TG neurons that project to cerebral dura were assessed by labeling dural nociceptors with DiI. Results Immunohistochemistry demonstrated that TRPV1 channels are present in cerebral dura, trigeminal ganglion, and in the trigeminal nucleus caudalis. Capsaicin, a TRPV1 agonist, produced depolarization and repetitive action potential firing in current clamp recordings and large inward currents in voltage clamp recordings from acutely dissociated TG neurons, demonstrating that TRPV1 channels are functional in trigeminal neurons. Capsaicin increased spontaneous excitatory postsynaptic currents (sEPSCs) in neurons of layer II in TNC slices, showing that these channels have a physiological effect on central synaptic transmission. Sumatriptan (10 μM), a selective anti-migraine drug inhibited TRPV1-mediated inward currents in TG. and

  5. Dietary Capsaicin Protects Cardiometabolic Organs from Dysfunction.

    PubMed

    Sun, Fang; Xiong, Shiqiang; Zhu, Zhiming

    2016-01-01

    Chili peppers have a long history of use for flavoring, coloring, and preserving food, as well as for medical purposes. The increased use of chili peppers in food is very popular worldwide. Capsaicin is the major pungent bioactivator in chili peppers. The beneficial effects of capsaicin on cardiovascular function and metabolic regulation have been validated in experimental and population studies. The receptor for capsaicin is called the transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is ubiquitously distributed in the brain, sensory nerves, dorsal root ganglia, bladder, gut, and blood vessels. Activation of TRPV1 leads to increased intracellular calcium signaling and, subsequently, various physiological effects. TRPV1 is well known for its prominent roles in inflammation, oxidation stress, and pain sensation. Recently, TRPV1 was found to play critical roles in cardiovascular function and metabolic homeostasis. Experimental studies demonstrated that activation of TRPV1 by capsaicin could ameliorate obesity, diabetes, and hypertension. Additionally, TRPV1 activation preserved the function of cardiometabolic organs. Furthermore, population studies also confirmed the beneficial effects of capsaicin on human health. The habitual consumption of spicy foods was inversely associated with both total and certain causes of specific mortality after adjustment for other known or potential risk factors. The enjoyment of spicy flavors in food was associated with a lower prevalence of obesity, type 2 diabetes, and cardiovascular diseases. These results suggest that capsaicin and TRPV1 may be potential targets for the management of cardiometabolic vascular diseases and their related target organs dysfunction. PMID:27120617

  6. Dietary Capsaicin Protects Cardiometabolic Organs from Dysfunction

    PubMed Central

    Sun, Fang; Xiong, Shiqiang; Zhu, Zhiming

    2016-01-01

    Chili peppers have a long history of use for flavoring, coloring, and preserving food, as well as for medical purposes. The increased use of chili peppers in food is very popular worldwide. Capsaicin is the major pungent bioactivator in chili peppers. The beneficial effects of capsaicin on cardiovascular function and metabolic regulation have been validated in experimental and population studies. The receptor for capsaicin is called the transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is ubiquitously distributed in the brain, sensory nerves, dorsal root ganglia, bladder, gut, and blood vessels. Activation of TRPV1 leads to increased intracellular calcium signaling and, subsequently, various physiological effects. TRPV1 is well known for its prominent roles in inflammation, oxidation stress, and pain sensation. Recently, TRPV1 was found to play critical roles in cardiovascular function and metabolic homeostasis. Experimental studies demonstrated that activation of TRPV1 by capsaicin could ameliorate obesity, diabetes, and hypertension. Additionally, TRPV1 activation preserved the function of cardiometabolic organs. Furthermore, population studies also confirmed the beneficial effects of capsaicin on human health. The habitual consumption of spicy foods was inversely associated with both total and certain causes of specific mortality after adjustment for other known or potential risk factors. The enjoyment of spicy flavors in food was associated with a lower prevalence of obesity, type 2 diabetes, and cardiovascular diseases. These results suggest that capsaicin and TRPV1 may be potential targets for the management of cardiometabolic vascular diseases and their related target organs dysfunction. PMID:27120617

  7. Capsaicin, Nociception and Pain.

    PubMed

    Frias, Bárbara; Merighi, Adalberto

    2016-01-01

    Capsaicin, the pungent ingredient of the hot chili pepper, is known to act on the transient receptor potential cation channel vanilloid subfamily member 1 (TRPV1). TRPV1 is involved in somatic and visceral peripheral inflammation, in the modulation of nociceptive inputs to spinal cord and brain stem centers, as well as the integration of diverse painful stimuli. In this review, we first describe the chemical and pharmacological properties of capsaicin and its derivatives in relation to their analgesic properties. We then consider the biochemical and functional characteristics of TRPV1, focusing on its distribution and biological effects within the somatosensory and viscerosensory nociceptive systems. Finally, we discuss the use of capsaicin as an agonist of TRPV1 to model acute inflammation in slices and other ex vivo preparations. PMID:27322240

  8. AB259. TRPV1 receptor associated with detrusor overactivity induced by partial bladder outlet obstruction in rats

    PubMed Central

    Zhang, Zhaocun; Zhu, Yanfeng; Chen, Jun; Jiang, Xuewen; Shang, Zhenhua; Shi, Benkang

    2016-01-01

    Background To investigate the role of TRPV1 in the pathological process of DO induced by partial bladder outlet obstruction (pBOO). Methods In 40 female Wistar rats, pBOO was achieved by partial urethral ligation and urodynamic analysis was taken to filter the DO rats six weeks later. Urinary bladder and dorsal root ganglia (DRG) were removed and RT-PCR, Western Blot and IHC were performed to investigate the expression and location of TRPV1 in control and DO rats. Effect of different concentrations of TRPV1 agonist, as well as TRPV1 antagonist, was also evaluated with isolated detrusor strips. Results Forty female Wistar rats received pBOO surgery and 24 of them developed DO. Expression of TRPV1 mRNA and protein in urinary bladder and dorsal root ganglia (DRG) significantly increased in pBOO induced OAB rats. While that did not significantly change after de-urothelial treatment both in OAB and control rats. Immunohistochemistry observed linear TRPV1-reactive staining mainly in suburothlial and muscular layer. In isolated detrusor strips studies, the amplitude and frequency of contractions of DO tissues were significantly higher than that of control ones (P<0.05). Capsaicin significantly increased the amplitude but not frequency of detrusor intrinsic contractility and this effect was enhanced in OAB conditions. All changes induced by capsaicin were blocked by capsazepine pre-incubated. Conclusions In pBOO induced DO rats, over-expressed TRPV1 was involved in DO pathological process by directly sensitizing bladder afferent fibers or indirectly enhancing detrusor intrinsic properties.

  9. Partial Activation and Inhibition of TRPV1 Channels by Evodiamine and Rutaecarpine, Two Major Components of the Fruits of Evodia rutaecarpa.

    PubMed

    Wang, Shenglan; Yamamoto, Satoshi; Kogure, Yoko; Zhang, Wensheng; Noguchi, Koichi; Dai, Yi

    2016-05-27

    Evodiamine (1) and rutaecarpine (2) are the two major components of Evodia rutaecarpa, which has long been used in traditional medicine for the treatment of many diseases. Using transient receptor potential vanilloid 1 (TRPV1)-expressing HEK293 cells and patch-clamp recording, the inhibitory actions of 1 and 2 against TRPV1 channels were investigated. The effects of these compounds against capsaicin- or proton-activated TRPV1 activities were evaluated. The results showed that, although 1 and 2 can activate TRPV1, the maximum response was 3.5- or 9-fold lower than that of capsaicin, respectively, suggesting partial agonism. In comparison to capsaicin, coadministration of 1 and capsaicin increased the half-maximal effective concentration (EC50) of capsaicin-activated TRPV1 currents as shown by a right shift in the dose-response curve, whereas coadministration of 1 with protons failed to inhibit the proton-induced current. Moreover, preadministration of 1, but not 2, inhibited both capsaicin- and proton-induced TRPV1 currents, which might involve channel desensitization. Taken together, 1 and 2 may share the same binding site with capsaicin and act as partial agonists (antagonists) of TRPV1. Evodiamine (1), but not rutaecarpine (2), can desensitize or competitively inhibit the activity of TRPV1. PMID:27159637

  10. Sensitization by pulmonary reactive oxygen species of rat vagal lung C-fibers: the roles of the TRPV1, TRPA1, and P2X receptors.

    PubMed

    Ruan, Ting; Lin, Yu-Jung; Hsu, Tien-Huan; Lu, Shing-Hwa; Jow, Guey-Mei; Kou, Yu Ru

    2014-01-01

    Sensitization of vagal lung C-fibers (VLCFs) induced by mediators contributes to the pathogenesis of airway hypersensitivity, which is characterized by exaggerated sensory and reflex responses to stimulants. Reactive oxygen species (ROS) are mediators produced during airway inflammation. However, the role of ROS in VLCF-mediated airway hypersensitivity has remained elusive. Here, we report that inhalation of aerosolized 0.05% H2O2 for 90 s potentiated apneic responses to intravenous capsaicin (a TRPV1 receptor agonist), α,β-methylene-ATP (a P2X receptor agonist), and phenylbiguanide (a 5-HT3 receptor agonist) in anesthetized rats. The apneic responses to these three stimulants were abolished by vagatomy or by perivagal capsaicin treatment, a procedure that blocks the neural conduction of VLCFs. The potentiating effect of H2O2 on the apneic responses to these VLCF stimulants was prevented by catalase (an enzyme that degrades H2O2) and by dimethylthiourea (a hydroxyl radical scavenger). The potentiating effect of H2O2 on the apneic responses to capsaicin was attenuated by HC-030031 (a TRPA1 receptor antagonist) and by iso-pyridoxalphosphate-6-azophenyl-2',5'-disulphonate (a P2X receptor antagonist). The potentiating effect of H2O2 on the apneic responses to α,β-methylene-ATP was reduced by capsazepine (a TRPV1 receptor antagonist), and by HC-030031. The potentiating effect of H2O2 on the apneic responses to phenylbiguanide was totally abolished when all three antagonists were combined. Consistently, our electrophysiological studies revealed that airway delivery of aerosolized 0.05% H2O2 for 90 s potentiated the VLCF responses to intravenous capsaicin, α,β-methylene-ATP, and phenylbiguanide. The potentiating effect of H2O2 on the VLCF responses to phenylbiguanide was totally prevented when all antagonists were combined. Inhalation of 0.05% H2O2 indeed increased the level of ROS in the lungs. These results suggest that 1) increased lung ROS sensitizes VLCFs

  11. Neuronal TRPV1 activation regulates alveolar bone resorption by suppressing osteoclastogenesis via CGRP.

    PubMed

    Takahashi, Naoki; Matsuda, Yumi; Sato, Keisuke; de Jong, Petrus R; Bertin, Samuel; Tabeta, Koichi; Yamazaki, Kazuhisa

    2016-01-01

    The transient receptor potential vanilloid 1 (TRPV1) channel is abundantly expressed in peripheral sensory neurons where it acts as an important polymodal cellular sensor for heat, acidic pH, capsaicin, and other noxious stimuli. The oral cavity is densely innervated by afferent sensory neurons and is a highly specialized organ that protects against infections as well as physical, chemical, and thermal stresses in its capacity as the first part of the digestive system. While the function of TRPV1 in sensory neurons has been intensively studied in other organs, its physiological role in periodontal tissues is unclear. In this study we found that Trpv1(-/-) mice developed severe bone loss in an experimental model of periodontitis. Chemical ablation of TRPV1-expressing sensory neurons recapitulated the phenotype of Trpv1(-/-) mice, suggesting a functional link between neuronal TRPV1 signaling and periodontal bone loss. TRPV1 activation in gingival nerves induced production of the neuropeptide, calcitonin gene-related peptide (CGRP), and CGRP treatment inhibited osteoclastogenesis in vitro. Oral administration of the TRPV1 agonist, capsaicin, suppressed ligature-induced bone loss in mice with fewer tartrate-resistant acid phosphatase (TRAP)-positive cells in alveolar bone. These results suggest that neuronal TRPV1 signaling in periodontal tissue is crucial for the regulation of osteoclastogenesis via the neuropeptide CGRP. PMID:27388773

  12. Neuronal TRPV1 activation regulates alveolar bone resorption by suppressing osteoclastogenesis via CGRP

    PubMed Central

    Takahashi, Naoki; Matsuda, Yumi; Sato, Keisuke; de Jong, Petrus R.; Bertin, Samuel; Tabeta, Koichi; Yamazaki, Kazuhisa

    2016-01-01

    The transient receptor potential vanilloid 1 (TRPV1) channel is abundantly expressed in peripheral sensory neurons where it acts as an important polymodal cellular sensor for heat, acidic pH, capsaicin, and other noxious stimuli. The oral cavity is densely innervated by afferent sensory neurons and is a highly specialized organ that protects against infections as well as physical, chemical, and thermal stresses in its capacity as the first part of the digestive system. While the function of TRPV1 in sensory neurons has been intensively studied in other organs, its physiological role in periodontal tissues is unclear. In this study we found that Trpv1−/− mice developed severe bone loss in an experimental model of periodontitis. Chemical ablation of TRPV1-expressing sensory neurons recapitulated the phenotype of Trpv1−/− mice, suggesting a functional link between neuronal TRPV1 signaling and periodontal bone loss. TRPV1 activation in gingival nerves induced production of the neuropeptide, calcitonin gene-related peptide (CGRP), and CGRP treatment inhibited osteoclastogenesis in vitro. Oral administration of the TRPV1 agonist, capsaicin, suppressed ligature-induced bone loss in mice with fewer tartrate-resistant acid phosphatase (TRAP)-positive cells in alveolar bone. These results suggest that neuronal TRPV1 signaling in periodontal tissue is crucial for the regulation of osteoclastogenesis via the neuropeptide CGRP. PMID:27388773

  13. Unique Responses are Observed in Transient Receptor Potential Ankyrin 1 and Vanilloid 1 (TRPA1 and TRPV1) Co-Expressing Cells

    PubMed Central

    Sadofsky, Laura R.; Sreekrishna, Koti T.; Lin, Yakang; Schinaman, Renee; Gorka, Kate; Mantri, Yogita; Haught, John Christian; Huggins, Thomas G.; Isfort, Robert J.; Bascom, Charles C.; Morice, Alyn H.

    2014-01-01

    Transient receptor potential (TRP) ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are implicated in modulation of cough and nociception. In vivo, TRPA1 and TRPV1 are often co-expressed in neurons and TRPA1V1 hetero-tetramer formation is noted in cells co-transfected with the respective expression plasmids. In order to understand the impact of TRP receptor interaction on activity, we created stable cell lines expressing the TRPA1, TRPV1 and co-expressing the TRPA1 and TRPV1 (TRPA1V1) receptors. Among the 600 compounds screened against these receptors, we observed a number of compounds that activated the TRPA1, TRPV1 and TRPA1V1 receptors; compounds that activated TRPA1 and TRPA1V1; compounds that activated TRPV1 and TRPA1V1; compounds in which TRPA1V1 response was modulated by either TRPA1 or TRPV1; and compounds that activated only TRPV1 or TRPA1 or TRPA1V1; and one compound that activated TRPA1 and TRPV1, but not TRPA1V1. These results suggest that co-expression of TRPA1 and TRPV1 receptors imparts unique activation profiles different from that of cells expressing only TRPA1 or TRPV1. PMID:24921186

  14. POTENTIATION OF PULMONARY REFLEX RESPONSE TO CAPSAICIN 24 HOURS FOLLOWING WHOLE-BODY ACROLEIN EXPOSURE IS MEDIATED BY TRPV1

    EPA Science Inventory

    Pulmonary C-fibers are stimulated by irritant air pollutants producing apnea, bronchospasm, and decrease in HR. C-fiber chemoreflex activation is mediated by TRPV1 and release of substance P. While acrolein has been shown to stimulate C-fibers, the persistence of acrolein effect...

  15. TRPV1 stimulation triggers apoptotic cell death of rat cortical neurons

    SciTech Connect

    Shirakawa, Hisashi; Yamaoka, Tomoko; Sanpei, Kazuaki; Sasaoka, Hirotoshi; Nakagawa, Takayuki; Kaneko, Shuji

    2008-12-26

    Transient receptor potential vanilloid 1 (TRPV1) functions as a polymodal nociceptor and is activated by several vanilloids, including capsaicin, protons and heat. Although TRPV1 channels are widely distributed in the brain, their roles remain unclear. Here, we investigated the roles of TRPV1 in cytotoxic processes using TRPV1-expressing cultured rat cortical neurons. Capsaicin induced severe neuronal death with apoptotic features, which was completely inhibited by the TRPV1 antagonist capsazepine and was dependent on extracellular Ca{sup 2+} influx. Interestingly, nifedipine, a specific L-type Ca{sup 2+} channel blocker, attenuated capsaicin cytotoxicity, even when applied 2-4 h after the capsaicin. ERK inhibitor PD98059 and several antioxidants, but not the JNK and p38 inhibitors, attenuated capsaicin cytotoxicity. Together, these data indicate that TRPV1 activation triggers apoptotic cell death of rat cortical cultures via L-type Ca{sup 2+} channel opening, Ca{sup 2+} influx, ERK phosphorylation, and reactive oxygen species production.

  16. TRPV1 function is modulated by Cdk5-mediated phosphorylation: insights into the molecular mechanism of nociception

    PubMed Central

    Jendryke, Thomas; Prochazkova, Michaela; Hall, Bradford E.; Nordmann, Grégory C.; Schladt, Moritz; Milenkovic, Vladimir M.; Kulkarni, Ashok B.; Wetzel, Christian H.

    2016-01-01

    TRPV1 is a polymodally activated cation channel acting as key receptor in nociceptive neurons. Its function is strongly affected by kinase-mediated phosphorylation leading to hyperalgesia and allodynia. We present behavioral and molecular data indicating that TRPV1 is strongly modulated by Cdk5-mediated phosphorylation at position threonine-407(mouse)/T406(rat). Increasing or decreasing Cdk5 activity in genetically engineered mice has severe consequences on TRPV1-mediated pain perception leading to altered capsaicin consumption and sensitivity to heat. To understand the molecular and structural/functional consequences of TRPV1 phosphorylation, we generated various rTRPV1T406 receptor variants to mimic phosphorylated or dephosphorylated receptor protein. We performed detailed functional characterization by means of electrophysiological whole-cell and single-channel recordings as well as Ca2+-imaging and challenged recombinant rTRPV1 receptors with capsaicin, low pH, or heat. We found that position T406 is critical for the function of TRPV1 by modulating ligand-sensitivity, activation, and desensitization kinetics as well as voltage-dependence. Based on high resolution structures of TRPV1, we discuss T406 being involved in the molecular transition pathway, its phosphorylation leading to a conformational change and influencing the gating of the receptor. Cdk5-mediated phosphorylation of T406 can be regarded as an important molecular switch modulating TRPV1-related behavior and pain sensitivity. PMID:26902776

  17. TRPV1 function is modulated by Cdk5-mediated phosphorylation: insights into the molecular mechanism of nociception.

    PubMed

    Jendryke, Thomas; Prochazkova, Michaela; Hall, Bradford E; Nordmann, Grégory C; Schladt, Moritz; Milenkovic, Vladimir M; Kulkarni, Ashok B; Wetzel, Christian H

    2016-01-01

    TRPV1 is a polymodally activated cation channel acting as key receptor in nociceptive neurons. Its function is strongly affected by kinase-mediated phosphorylation leading to hyperalgesia and allodynia. We present behavioral and molecular data indicating that TRPV1 is strongly modulated by Cdk5-mediated phosphorylation at position threonine-407(mouse)/T406(rat). Increasing or decreasing Cdk5 activity in genetically engineered mice has severe consequences on TRPV1-mediated pain perception leading to altered capsaicin consumption and sensitivity to heat. To understand the molecular and structural/functional consequences of TRPV1 phosphorylation, we generated various rTRPV1T406 receptor variants to mimic phosphorylated or dephosphorylated receptor protein. We performed detailed functional characterization by means of electrophysiological whole-cell and single-channel recordings as well as Ca(2+)-imaging and challenged recombinant rTRPV1 receptors with capsaicin, low pH, or heat. We found that position T406 is critical for the function of TRPV1 by modulating ligand-sensitivity, activation, and desensitization kinetics as well as voltage-dependence. Based on high resolution structures of TRPV1, we discuss T406 being involved in the molecular transition pathway, its phosphorylation leading to a conformational change and influencing the gating of the receptor. Cdk5-mediated phosphorylation of T406 can be regarded as an important molecular switch modulating TRPV1-related behavior and pain sensitivity. PMID:26902776

  18. Estrogen-dependent up-regulation of TRPA1 and TRPV1 receptor proteins in the rat endometrium.

    PubMed

    Pohóczky, Krisztina; Kun, József; Szalontai, Bálint; Szőke, Éva; Sághy, Éva; Payrits, Maja; Kajtár, Béla; Kovács, Krisztina; Környei, József László; Garai, János; Garami, András; Perkecz, Anikó; Czeglédi, Levente; Helyes, Zsuzsanna

    2016-02-01

    Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors expressed predominantly in sensory nerves are activated by inflammatory stimuli and mediate inflammation and pain. Although they have been shown in the human endometrium, their regulation and function are unknown. Therefore, we investigated their estrogen- and progesterone-dependent alterations in the rat endometrium in comparison with the estrogen-regulated inflammatory cytokine macrophage migration inhibitory factor (MIF). Four-week-old (sexually immature) and four-month-old (sexually mature) female rats were treated with the non-selective estrogen receptor (ER) agonist diethylstilboestrol (DES), progesterone and their combination, or ovariectomized. RT-PCR and immunohistochemistry were performed to determine mRNA and protein expression levels respectively. Channel function was investigated with ratiometric [Ca(2+)]i measurement in cultured primary rat endometrial cells. Both TRP receptors and MIF were detected in the endometrium at mRNA and protein levels, and their localizations were similar. Immunostaining was observed in the immature epithelium, while stromal, glandular and epithelial positivity were observed in adults. Functionally active TRP receptor proteins were shown in endometrial cells by activation-induced calcium influx. In adults, Trpa1 and Trpv1 mRNA levels were significantly up-regulated after DES treatment. TRPA1 increased after every treatment, but TRPV1 remained unchanged following the combined treatment and ovariectomy. In immature rats, DES treatment resulted in increased mRNA expression of both channels and elevated TRPV1 immunopositivity. MIF expression changed in parallel with TRPA1/TRPV1 in most cases. DES up-regulated Trpa1, Trpv1 and Mif mRNA levels in endometrial cell cultures, but 17β-oestradiol having ERα-selective potency increased only the expression of Trpv1. We provide the first evidence for TRPA1/TRPV1 expression and their estrogen-induced up

  19. NMDA receptors are involved in the antidepressant-like effects of capsaicin following amphetamine withdrawal in male mice.

    PubMed

    Amiri, Shayan; Alijanpour, Sakineh; Tirgar, Fatemeh; Haj-Mirzaian, Arya; Amini-Khoei, Hossein; Rahimi-Balaei, Maryam; Rastegar, Mojgan; Ghaderi, Marzieh; Ghazi-Khansari, Mahmoud; Zarrindast, Mohammad-Reza

    2016-08-01

    Amphetamine withdrawal (AW) is accompanied by diminished pleasure and depression which plays a key role in drug relapse and addictive behaviors. There is no efficient treatment for AW-induced depression and underpinning mechanisms were not well determined. Considering both transient receptor potential cation channel, subfamily V, member 1 (TRPV1) and N-Methyl-d-aspartate (NMDA) receptors contribute to pathophysiology of mood and addictive disorders, in this study, we investigated the role of TRPV1 and NMDA receptors in mediating depressive-like behaviors following AW in male mice. Results revealed that administration of capsaicin, TRPV1 agonist, (100μg/mouse, i.c.v.) and MK-801, NMDA receptor antagonist (0.005mg/kg, i.p.) reversed AW-induced depressive-like behaviors in forced swimming test (FST) and splash test with no effect on animals' locomotion. Co-administration of sub-effective doses of MK-801 (0.001mg/kg, i.p.) and capsaicin (10μg/mouse, i.c.v) exerted antidepressant-like effects in behavioral tests. Capsazepine, TRPV1 antagonist, (100μg/mouse, i.c.v) and NMDA, NMDA receptor agonist (7.5mg/kg, i.p.) abolished the effects of capsaicin and MK-801, respectively. None of aforementioned treatments had any effect on behavior of control animals. Collectively, our findings showed that activation of TRPV1 and blockade of NMDA receptors produced antidepressant-like effects in male mice following AW, and these receptors are involved in AW-induced depressive-like behaviors. Further, we found that rapid antidepressant-like effects of capsaicin in FST and splash test are partly mediated by NMDA receptors. PMID:27167081

  20. Functional TRPV1 expression in human corneal fibroblasts.

    PubMed

    Yang, Yuanquan; Yang, Hua; Wang, Zheng; Mergler, Stefan; Wolosin, J Mario; Reinach, Peter S

    2013-02-01

    Corneal wound healing in mice subsequent to an alkali burn results in dysregulated inflammation and opacification. Transient receptor potential vanilloid subtype 1 (TRPV1) channel activation in all tissue layers by endogenous ligands contributes to this sight compromising outcome since in TRPV1 knockout mice wound healing results instead in tissue transparency restoration. However, it is not known if primary human stromal fibroblasts exhibit such expression even though functional TRPV1 expression is evident in an immortalized human corneal epithelial cell line. In primary human corneal fibroblasts (HCF), TRPV1 gene expression and localization were identified based on the results of quantitative RT-PCR and immunocytochemistry, respectively. Western blot analysis identified a 100 kD protein corresponding to TRPV1 protein expression in a positive control. Single-cell fluorescence imaging detected in fura2-AM loaded cells Ca(2+) transients that rose 1.8-fold above the baseline induced by a selective TRPV1 agonist, capsaicin (CAP), which were blocked by a TRPV1 antagonist, capsazepine (CPZ) or exposure to a Ca(2+) free medium. The whole-cell mode of the planar patch-clamp technique identified TRPV1-induced currents that rose 1.76-fold between -60 and +130 mV. CAP-induced time dependent changes in the phosphorylation status of mitogen activated protein kinase (MAPK) signaling mediators that led to a 2.5-fold increase in IL-6 release after 24 h. This rise did not occur either in TRPV1 siRNA gene silenced cells or during exposure to SB203580 (10 μM), a selective p38 MAPK inhibitor. Taken together, identification of functional TRPV1 expression in HCF suggests that in vivo its activation by injury contributes to corneal opacification and inflammation during wound healing. These undesirable effects may result in part from increases in IL-6 expression mediated by p-p38 MAPK signaling. PMID:23232207

  1. TRPV1 sensitization mediates postinflammatory visceral pain following acute colitis.

    PubMed

    Lapointe, Tamia K; Basso, Lilian; Iftinca, Mircea C; Flynn, Robyn; Chapman, Kevin; Dietrich, Gilles; Vergnolle, Nathalie; Altier, Christophe

    2015-07-15

    Quiescent phases of inflammatory bowel disease (IBD) are often accompanied by chronic abdominal pain. Although the transient receptor potential vanilloid 1 (TRPV1) ion channel has been postulated as an important mediator of visceral hypersensitivity, its functional role in postinflammatory pain remains elusive. This study aimed at establishing the role of TRPV1 in the peripheral sensitization underlying chronic visceral pain in the context of colitis. Wild-type and TRPV1-deficient mice were separated into three groups (control, acute colitis, and recovery), and experimental colitis was induced by oral administration of dextran sulfate sodium (DSS). Recovery mice showed increased chemically and mechanically evoked visceral hypersensitivity 5 wk post-DSS discontinuation, at which point inflammation had completely resolved. Significant changes in nonevoked pain-related behaviors could also be observed in these animals, indicative of persistent discomfort. These behavioral changes correlated with elevated colonic levels of substance P (SP) and TRPV1 in recovery mice, thus leading to the hypothesis that SP could sensitize TRPV1 function. In vitro experiments revealed that prolonged exposure to SP could indeed sensitize capsaicin-evoked currents in both cultured neurons and TRPV1-transfected human embryonic kidney (HEK) cells, a mechanism that involved TRPV1 ubiquitination and subsequent accumulation at the plasma membrane. Importantly, although TRPV1-deficient animals experienced similar disease severity and pain as wild-type mice in the acute phase of colitis, TRPV1 deletion prevented the development of postinflammatory visceral hypersensitivity and pain-associated behaviors. Collectively, our results suggest that chronic exposure of colon-innervating primary afferents to SP could sensitize TRPV1 and thus participate in the establishment of persistent abdominal pain following acute inflammation. PMID:26021808

  2. TRPV1: A Potential Drug Target for Treating Various Diseases

    PubMed Central

    Brito, Rafael; Sheth, Sandeep; Mukherjea, Debashree; Rybak, Leonard P.; Ramkumar, Vickram

    2014-01-01

    Transient receptor potential vanilloid 1 (TRPV1) is an ion channel present on sensory neurons which is activated by heat, protons, capsaicin and a variety of endogenous lipids termed endovanilloids. As such, TRPV1 serves as a multimodal sensor of noxious stimuli which could trigger counteractive measures to avoid pain and injury. Activation of TRPV1 has been linked to chronic inflammatory pain conditions and peripheral neuropathy, as observed in diabetes. Expression of TRPV1 is also observed in non-neuronal sites such as the epithelium of bladder and lungs and in hair cells of the cochlea. At these sites, activation of TRPV1 has been implicated in the pathophysiology of diseases such as cystitis, asthma and hearing loss. Therefore, drugs which could modulate TRPV1 channel activity could be useful for the treatment of conditions ranging from chronic pain to hearing loss. This review describes the roles of TRPV1 in the normal physiology and pathophysiology of selected organs of the body and highlights how drugs targeting this channel could be important clinically. PMID:24861977

  3. The Chimeric Approach Reveals That Differences in the TRPV1 Pore Domain Determine Species-specific Sensitivity to Block of Heat Activation*

    PubMed Central

    Papakosta, Marianthi; Dalle, Carine; Haythornthwaite, Alison; Cao, Lishuang; Stevens, Edward B.; Burgess, Gillian; Russell, Rachel; Cox, Peter J.; Phillips, Stephen C.; Grimm, Christian

    2011-01-01

    The capsaicin-, heat-, and proton-activated ion channel TRPV1, a member of the transient receptor potential cation channel family is a polymodal nociceptor. For almost a decade, TRPV1 has been explored by the pharmaceutical industry as a potential target for example for pain conditions. Antagonists which block TRPV1 activation by capsaicin, heat, and protons were developed by a number of pharmaceutical companies. The unexpected finding of hyperthermia as an on-target side effect in clinical studies using polymodal TRPV1 antagonists has prompted companies to search for ways to circumvent hyperthermia, for example by the development of modality-selective antagonists. The significant lack of consistency of the pharmacology of many TRPV1 antagonists across different species has been a further obstacle. JYL-1421 for example was shown to block capsaicin and heat responses in human and monkey TRPV1 while it was largely ineffective in blocking heat responses in rat TRPV1. These findings suggested structural dissimilarities between different TRPV1 species relevant for small compound antagonism for example of heat activation. Using a chimeric approach (human and rat TRPV1) in combination with a novel FLIPR-based heat activation assay and patch-clamp electrophysiology we have identified the pore region as being strongly linked to the observed species differences. We demonstrate that by exchanging the pore domains JYL-1421, which is modality-selective in rat can be made modality-selective in human TRPV1 and vice-versa. PMID:21911503

  4. Electrophysiological characteristics of IB4-negative TRPV1-expressing muscle afferent DRG neurons

    PubMed Central

    Lin, Yi-Wen; Chen, Chih-Cheng

    2015-01-01

    Muscle afferent neurons that express transient receptor potential vanilloid type I (TRPV1) are responsible for muscle pain associated with tissue acidosis. We have previously found that TRPV1 of isolectin B4 (IB4)-negative muscle nociceptors plays an important role in the acid-induced hyperalgesic priming and the development of chronic hyperalgesia in a mouse model of fibromyalgia. To understand the electrophysiological properties of the TRPV1-expressing muscle afferent neurons, we used whole-cell patch clamp recording to study the acid responsiveness and action potential (AP) configuration of capsaicin-sensitive neurons innervating to gastrocnemius muscle. Here we showed that IB4-negative TRPV1-expressing muscle afferent neurons are heterogeneous in terms of cell size, resting membrane potential, AP configuration, tetrodotoxin (TTX)-resistance, and acid-induced current (Iacid), as well as capsaicin-induced current (Icap). TRPV1-expressing neurons were all acid-sensitive and could be divided into two acid-sensitive groups depending on an acid-induced sustained current (type I) or an acid-induced biphasic ASIC3-like current (type II). Type I TRPV1-expressing neurons were distinguishable from type II TRPV1-expressing neurons in AP overshoot, after-hyperpolarization duration, and all Iacid parameters, but not in AP threshold, TTX-resistance, resting membrane potential, and Icap parameters. These differential biophysical properties of TRPV1-expressing neurons might partially annotate their different roles involved in the development and maintenance of chronic muscle pain. PMID:27493509

  5. Reactive oxygen species mediate TNFR1 increase after TRPV1 activation in mouse DRG neurons

    PubMed Central

    Ma, Fei; Zhang, Liping; Westlund, Karin N

    2009-01-01

    Background Transient receptor potential vanilloid subtype 1 (TRPV1) is activated by low pH/protons and is well known to be involved in hyperalgesia during inflammation. Tumor necrosis factor α (TNF-α), a proinflammatory cytokine, is involved in nociceptive responses causing hyperalgesia through TNF receptor type 1 (TNFR1) activation. Reactive oxygen species (ROS) production is also prominently increased in inflamed tissue. The present study investigated TNFR1 receptors in primary cultured mouse dorsal root ganglion (DRG) neurons after TRPV1 activation and the involvement of ROS. C57BL/6 mice, both TRPV1 knockout and wild type, were used for immunofluorescent and live cell imaging. The L4 and L5 DRGs were dissected bilaterally and cultured overnight. TRPV1 was stimulated with capsaicin or its potent analog, resiniferatoxin. ROS production was measured with live cell imaging and TNFR1 was detected with immunofluorescence in DRG primary cultures. The TRPV1 knockout mice, TRPV1 antagonist, capsazepine, and ROS scavenger, N-tert-Butyl-α-phenylnitrone (PBN), were employed to explore the functional relationship among TRPV1, ROS and TNFR1 in these studies. Results The results demonstrate that TRPV1 activation increases TNFR1 receptors and ROS generation in primary cultures of mouse DRG neurons. Activated increases in TNFR1 receptors and ROS production are absent in TRPV1 deficient mice. The PBN blocks increases in TNFR1 and ROS production induced by capsaicin/resiniferatoxin. Conclusion TRPV1 activation increases TNFR1 in cultured mouse DRG neurons through a ROS signaling pathway, a novel sensitization mechanism in DRG neurons. PMID:19531269

  6. Pain-enhancing mechanism through interaction between TRPV1 and anoctamin 1 in sensory neurons

    PubMed Central

    Takayama, Yasunori; Uta, Daisuke; Furue, Hidemasa; Tominaga, Makoto

    2015-01-01

    The capsaicin receptor transient receptor potential cation channel vanilloid 1 (TRPV1) is activated by various noxious stimuli, and the stimuli are converted into electrical signals in primary sensory neurons. It is believed that cation influx through TRPV1 causes depolarization, leading to the activation of voltage-gated sodium channels, followed by the generation of action potential. Here we report that the capsaicin-evoked action potential could be induced by two components: a cation influx-mediated depolarization caused by TRPV1 activation and a subsequent anion efflux-mediated depolarization via activation of anoctamin 1 (ANO1), a calcium-activated chloride channel, resulting from the entry of calcium through TRPV1. The interaction between TRPV1 and ANO1 is based on their physical binding. Capsaicin activated the chloride currents in an extracellular calcium-dependent manner in HEK293T cells expressing TRPV1 and ANO1. Similarly, in mouse dorsal root ganglion neurons, capsaicin-activated inward currents were inhibited significantly by a specific ANO1 antagonist, T16Ainh-A01 (A01), in the presence of a high concentration of EGTA but not in the presence of BAPTA [1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid]. The generation of a capsaicin-evoked action potential also was inhibited by A01. Furthermore, pain-related behaviors in mice treated with capsaicin, but not with αβ-methylene ATP, were reduced significantly by the concomitant administration of A01. These results indicate that TRPV1–ANO1 interaction is a significant pain-enhancing mechanism in the peripheral nervous system. PMID:25848051

  7. Transient Receptor Potential Vanilloid-1 (TRPV1) Is a Mediator of Lung Toxicity for Coal Fly Ash Particulate Material

    PubMed Central

    Deering-Rice, Cassandra E.; Johansen, Mark E.; Roberts, Jessica K.; Thomas, Karen C.; Romero, Erin G.; Lee, Jeewoo; Yost, Garold S.; Veranth, John M.

    2012-01-01

    Environmental particulate matter (PM) pollutants adversely affect human health, but the molecular basis is poorly understood. The ion channel transient receptor potential vanilloid-1 (TRPV1) has been implicated as a sensor for environmental PM and a mediator of adverse events in the respiratory tract. The objectives of this study were to determine whether TRPV1 can distinguish chemically and physically unique PM that represents important sources of air pollution; to elucidate the molecular basis of TRPV1 activation by PM; and to ascertain the contributions of TRPV1 to human lung cell and mouse lung tissue responses exposed to an insoluble PM agonist, coal fly ash (CFA1). The major findings of this study are that TRPV1 is activated by some, but not all of the prototype PM materials evaluated, with rank-ordered responses of CFA1 > diesel exhaust PM > crystalline silica; TRP melastatin-8 is also robustly activated by CFA1, whereas other TRP channels expressed by airway sensory neurons and lung epithelial cells that may also be activated by CFA1, including TRPs ankyrin 1 (A1), canonical 4α (C4α), M2, V2, V3, and V4, were either slightly (TRPA1) or not activated by CFA1; activation of TRPV1 by CFA1 occurs via cell surface interactions between the solid components of CFA1 and specific amino acid residues of TRPV1 that are localized in the putative pore-loop region; and activation of TRPV1 by CFA1 is not exclusive in mouse lungs but represents a pathway by which CFA1 affects the expression of selected genes in lung epithelial cells and airway tissue. PMID:22155782

  8. Transient receptor potential vanilloid-1 (TRPV1) is a mediator of lung toxicity for coal fly ash particulate material.

    PubMed

    Deering-Rice, Cassandra E; Johansen, Mark E; Roberts, Jessica K; Thomas, Karen C; Romero, Erin G; Lee, Jeewoo; Yost, Garold S; Veranth, John M; Reilly, Christopher A

    2012-03-01

    Environmental particulate matter (PM) pollutants adversely affect human health, but the molecular basis is poorly understood. The ion channel transient receptor potential vanilloid-1 (TRPV1) has been implicated as a sensor for environmental PM and a mediator of adverse events in the respiratory tract. The objectives of this study were to determine whether TRPV1 can distinguish chemically and physically unique PM that represents important sources of air pollution; to elucidate the molecular basis of TRPV1 activation by PM; and to ascertain the contributions of TRPV1 to human lung cell and mouse lung tissue responses exposed to an insoluble PM agonist, coal fly ash (CFA1). The major findings of this study are that TRPV1 is activated by some, but not all of the prototype PM materials evaluated, with rank-ordered responses of CFA1 > diesel exhaust PM > crystalline silica; TRP melastatin-8 is also robustly activated by CFA1, whereas other TRP channels expressed by airway sensory neurons and lung epithelial cells that may also be activated by CFA1, including TRPs ankyrin 1 (A1), canonical 4α (C4α), M2, V2, V3, and V4, were either slightly (TRPA1) or not activated by CFA1; activation of TRPV1 by CFA1 occurs via cell surface interactions between the solid components of CFA1 and specific amino acid residues of TRPV1 that are localized in the putative pore-loop region; and activation of TRPV1 by CFA1 is not exclusive in mouse lungs but represents a pathway by which CFA1 affects the expression of selected genes in lung epithelial cells and airway tissue. PMID:22155782

  9. Competitive inhibition of TRPV1-calmodulin interaction by vanilloids.

    PubMed

    Hetényi, Anasztázia; Németh, Lukács; Wéber, Edit; Szakonyi, Gerda; Winter, Zoltán; Jósvay, Katalin; Bartus, Éva; Oláh, Zoltán; Martinek, Tamás A

    2016-08-01

    There is enormous interest toward vanilloid agonists of the pain receptor TRPV1 in analgesic therapy, but the mechanisms of their sensory neuron-blocking effects at high or repeated doses are still a matter of debate. Our results have demonstrated that capsaicin and resiniferatoxin form nanomolar complexes with calmodulin, and competitively inhibit TRPV1-calmodulin interaction. These interactions involve the protein recognition interface of calmodulin, which is responsible for all of the cell-regulatory calmodulin-protein interactions. These results draw attention to a previously unknown vanilloid target, which may contribute to the explanation of the paradoxical pain-modulating behavior of these important pharmacons. PMID:27339229

  10. Oleoylethanolamide reduces L-DOPA-induced dyskinesia via TRPV1 receptor in a mouse model of Parkinson´s disease.

    PubMed

    González-Aparicio, Ramiro; Moratalla, Rosario

    2014-02-01

    The long-term use of levodopa (L-DOPA) in Parkinson's disease (PD) results in the development of abnormal involuntary movements called L-DOPA-induced dyskinesias. Increasing evidences suggest that the endocannabinoid system may play a role in the modulation of dyskinesias. In this work, we assessed the antidyskinetic effect of the endocannabinoid analog oleoylethanolamide (OEA), an agonist of PPARα and antagonist of TRPV1 receptors. We used a hemiparkinsonian model of PD in mice with 6-OHDA striatal lesion. The chronic L-DOPA treatment developed intense axial, forelimb and orolingual dyskinetic symptoms, as well as contralateral rotations. Treatment with OEA reduced all these symptoms without reducing motor activity or the therapeutic motor effects of L-DOPA. Moreover, the OEA-induced reduction in dyskinetic behavior correlated with a reduction in molecular correlates of dyskinesia. OEA reduced FosB striatal overexpression and phosphoacetylation of histone 3, both molecular markers of L-DOPA-induced dyskinesias. We found that OEA antidyskinetic properties were mediated by TRPV1 receptor, as pretreatment with capsaicin, a TRPV1 agonist, blocked OEA antidyskinetic actions, as well as the reduction in FosB- and pAcH3-overexpression induced by L-DOPA. This study supports the hypothesis that the endocannabinoid system plays an important role in the development and expression of dyskinesias and might be an effective target for the treatment of L-DOPA-induced dyskinesias. Importantly, there was no development of tolerance to OEA in any of the parameters we examined, which has important implications for the therapeutic potential of drugs targeting the endocannabinoid system. PMID:24140894

  11. Comparison of the effects of pelargonic acid vanillylamide and capsaicin on human vanilloid receptors.

    PubMed

    Weiser, Thomas; Roufogalis, Basil; Chrubasik, Sigrun

    2013-07-01

    Pelargonic acid vanillylamide is like capsaicin a natural capsaicinoid from chili peppers and commonly used in food additives to create a hot sensation, even in self-defense pepper sprays and as an alternative to capsaicin in medical products for topical treatment of pain. Although the chemical structures of both compounds are similar, preclinical data suggest that capsaicin is the more potent compound. We therefore performed voltage-clamp recordings using cells transfected with the human vanilloid receptor TRPV1 in order to assess the responses of pelargonic acid vanillylamide and capsaicin at the receptor level. We provide evidence that at the molecular target TRPV1, the concentration-response curves, kinetics of current activation, as well as inhibition by the competitive antagonist capsazepine were not significantly different between the two capsaicinoids. We suggest that the different effects of the two capsaicinoids observed in previous studies may rather be due to different physicochemical or pharmacokinetic properties than to different pharmacological profiles at the receptor level. PMID:22961689

  12. TRPV1-Mediated Neuropeptide Secretion and Depressor Effects: Role of Endoplasmic Reticulum-Associated Ca2+ Release Receptors in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Huang, Wei; Wang, Hui; Galligan, James J.; Wang, Donna H.

    2009-01-01

    Objective This study tests the hypothesis that the transient receptor potential vanilloid subtype 1 (TRPV1)-induced neuropeptide secretion and depressor response are mediated by, at least in part, activation of endoplasmic reticulum (ER)-associated Ca2+ release receptors, leading to increased cytosolic Ca2+ in dorsal root ganglion (DRG) neurons. Methods/Results Bolus injection of capsaicin (CAP, 10 or 50 μg/kg), a selective TRPV1 agonist, into anesthetized male Wistar rats caused dose-dependent decreases in mean arterial pressure (MAP, P<0.05). CAP (50 μg/kg)-induced depressor effects and increases in plasma calcitonin gene-related peptide (CGRP) levels (-29±2 mmHg, 82.2±5.0 pg/ml, respectively) were abolished by a selective TRPV1 antagonist, capsazepine (3 mg/kg CAPZ, -4±1 mmHg, 41.8±4.4 pg/ml, P<0.01), and attenuated by a selective ryanodine receptor (RyR) antagonist, dantrolene (5 mg/kg, -12±1 mmHg, 57.2±2.6 pg/ml, P<0.01), but unaffected by an inhibitor of ER Ca2+-ATPase, thapsigargin (50 μg/kg TG, -30±1 mmHg, 73.8±2.3 pg/ml, P>0.05), or an antagonist of the inositol (1,4,5)-trisphosphate receptor (IP3R), 2-aminoethoxydiphenyl borate (3 mg/kg 2-APB, -34±5 mmHg, 69.0±3.7 pg/ml, P>0.05). CGRP8-37 (1 mg/kg), a selective CGRP receptor antagonist, also blocked CAP-induced depressor effects. In contrast, dantrolene had no effect on CGRP (1 μg/kg)-induced depressor effects. In vitro, CAP (0.3 μM) increased intracellular Ca2+ concentrations and CGRP release from freshly isolated sensory neurons in DRG (P<0.01), which were blocked by CAPZ (10 μM) and attenuated by dantrolene but not TG or 2-APB. Conclusion Our results indicate that TRPV1 activation triggers RyR- but not IP3R-dependent Ca2+ release from ER in DRG neurons leading to increased CGRP release and consequent depressor effects. PMID:18806620

  13. Ursolic acid from Agastache mexicana aerial parts produces antinociceptive activity involving TRPV1 receptors, cGMP and a serotonergic synergism.

    PubMed

    Verano, Jazmín; González-Trujano, Ma Eva; Déciga-Campos, Myrna; Ventura-Martínez, Rosa; Pellicer, Francisco

    2013-09-01

    Agastache mexicana is a plant that has long been used in large demands in Mexican folk medicine to treat anxiety, insomnia and pain, among others affections. Chromatographic technique was used to identify ursolic acid (UA), 130.7 mg/g and 20.3 mg/g, as an antinociceptive active compound identified in ethyl acetate and methanol extracts of A. mexicana aerial parts, respectively. Temporal course curves of the antinociceptive response demonstrated a dose-dependent and significant activity of UA (1 to 100 mg/kg, i.p.) with an ED50=2 mg/kg in comparison to the efficacy of diclofenac (1 or 30 to 100 mg/kg, i.p.), a non-steroidal anti-inflammatory drug, with an ED50=11.56 mg/kg. The antinociceptive response consisted in the reduction of abdominal constrictions induced with 1% acetic acid in mice. Similarly, UA at 2 mg/kg produced significant antinociception in the intracolonic administration of 0.3% capsaicin (a TRPV1 agonist) in mice. It has been reported the inhibition produced by UA on the calcium-flux induced by capsaicin on TRPV1 receptor suggesting the antagonistic activity of this receptor. Finally, an ED50=44 mg/kg was calculated in the neurogenic and inflammatory nociception induced in the formalin test in rats. The antinociceptive response of UA in the formalin test was not modified in presence of naloxone, flumazenil or L-arginine. Nevertheless, it was reverted in presence of 1-H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one (ODQ, an inhibitor of soluble guanylyl cyclase) and increased in presence of N(G)-L-nitro-arginine methyl ester (L-NAME, inhibitor of nitric oxide synthase), theophylline (inhibitor of phosphodiesterase) and WAY100635 (an antagonist of 5-HT1A receptors). Current results provide evidence that the antinociceptive response of A. mexicana depends in part on the presence of UA. Moreover, this triterpene may exerts its antinociceptive effect mediated by the presence of cGMP and an additive synergism with 5HT1A receptors, but also an antagonistic

  14. [Interaction of sea amemone Heteractis crispa Kunitz type polypeptides with pain vanilloid receptor TRPV1: in silico investigation].

    PubMed

    Zelepuga, E A; Tabakmakher, V M; Chausova, V E; monastyrnaia, M M; Isaeva, M P; Kozlovskaia, É P

    2012-01-01

    Using methods of molecular biology we defined the structures of the 31 sea anemone Heteractis crispa genes encoding polypeptides which are structurally homologous to the Kunitz proteinase inhibitor family. Identified amino acid sequences have point residue substitutions, high degree of homology with sequences of known H. crispa Kunitz family members, and represent a combinatorial library of polypeptides. We generated their three-dimensional structures by homologous modeling methods. Analysis of their molecular electrostatic potential enabled us to divide given polypeptides into three clusters. One of them includes polypeptides APHC1, APHC2 and APHC3, which were earlier shown to possess a unique property of inhibiting of the pain vanilloid receptor TRPV1 in vitro and providing the analgesic effects in vivo in addition to their trypsin inhibitory activity. Molecular docking made possible establishing the spatial structure of the complexes, the nature of the polypeptides binding with TRPV1, as well as functionally important structural elements involved in the complex formation. Structural models have enabled us to propose a hypothesis contributing to understanding the APHC1-3 impact mechanism for the pain signals transduction by TRPV1: apparently, there is an increase of the receptor relaxation time resulted in binding of its two chains with the polypeptide molecule, which disrupt the functioning of the TRPV1 and leads to partial inhibition of signal transduction in electrophysiological experiments. PMID:22792722

  15. The TRPV1 channel in rodents is a major target for antinociceptive effect of the probiotic Lactobacillus reuteri DSM 17938.

    PubMed

    Perez-Burgos, Azucena; Wang, Lu; McVey Neufeld, Karen-Anne; Mao, Yu-Kang; Ahmadzai, Mustafa; Janssen, Luke J; Stanisz, Andrew M; Bienenstock, John; Kunze, Wolfgang A

    2015-09-01

    Certain probiotic bacteria have been shown to reduce distension-dependent gut pain, but the mechanisms involved remain obscure. Live luminal Lactobacillus reuteri (DSM 17938) and its conditioned medium dose dependently reduced jejunal spinal nerve firing evoked by distension or capsaicin, and 80% of this response was blocked by a specific TRPV1 channel antagonist or in TRPV1 knockout mice. The specificity of DSM action on TRPV1 was further confirmed by its inhibition of capsaicin-induced intracellular calcium increases in dorsal root ganglion neurons. Another lactobacillus with ability to reduce gut pain did not modify this response. Prior feeding of rats with DSM inhibited the bradycardia induced by painful gastric distension. These results offer a system for the screening of new and improved candidate bacteria that may be useful as novel therapeutic adjuncts in gut pain. Certain bacteria exert visceral antinociceptive activity, but the mechanisms involved are not determined. Lactobacillus reuteri DSM 17938 was examined since it may be antinociceptive in children. Since transient receptor potential vanilloid 1 (TRPV1) channel activity may mediate nociceptive signals, we hypothesized that TRPV1 current is inhibited by DSM. We tested this by examining the effect of DSM on the firing frequency of spinal nerve fibres in murine jejunal mesenteric nerve bundles following serosal application of capsaicin. We also measured the effects of DSM on capsaicin-evoked increase in intracellular Ca(2+) or ionic current in dorsal root ganglion (DRG) neurons. Furthermore, we tested the in vivo antinociceptive effects of oral DSM on gastric distension in rats. Live DSM reduced the response of capsaicin- and distension-evoked firing of spinal nerve action potentials (238 ± 27.5% vs. 129 ± 17%). DSM also reduced the capsaicin-evoked TRPV1 ionic current in DRG neuronal primary culture from 83 ± 11% to 41 ± 8% of the initial response to capsaicin only. Another lactobacillus

  16. Sulphur-containing compounds of durian activate the thermogenesis-inducing receptors TRPA1 and TRPV1.

    PubMed

    Terada, Yuko; Hosono, Takashi; Seki, Taiichiro; Ariga, Toyohiko; Ito, Sohei; Narukawa, Masataka; Watanabe, Tatsuo

    2014-08-15

    Durian (Durio zibethinus Murr.) is classified as a body-warming food in Indian herbalism, and its hyperthermic effect is empirically known in Southeast Asia. To investigate the mechanism underlying this effect, we focused on the thermogenesis-inducing receptors, TRPA1 and TRPV1. Durian contains sulphides similar to the TRPA1 and TRPV1 agonists of garlic. Accordingly, we hypothesized that the thermogenic effect of durian is driven by sulphide-induced TRP channel activation. To investigate our hypothesis, we measured the TRPA1 and TRPV1 activity of the sulphur-containing components of durian and quantified their content in durian pulp. These sulphur-containing components had a stronger effect on TRPA1 than TRPV1. Furthermore, sulphide content in the durian pulp was sufficient to evoke TRP channel activation and the main agonist was diethyl disulphide. From these results, we consider that the body-warming effect of durian is elicited by TRPA1 activation with its sulphides, as can be seen in spices. PMID:24679773

  17. Novel therapeutics in the field of capsaicin and pain.

    PubMed

    Evangelista, Stefano

    2015-01-01

    Capsaicin, a pharmacologically active agent found in chili peppers, causes burning and itching sensation due to binding at the transient receptor potential vanilloid-1 (TRPV-1) receptor, a polymodal receptor critical to the sensing of a variety of stimuli (e.g., noxious heat, bidirectional pH), and subsequent activation of polymodal C and A-δ nociceptive fibers. Acutely, TRPV-1 activation with peripheral capsaicin produces pronociceptive effects, which extends to the development of hyperalgesia and allodynia. However, capsaicin has been reported to display antinociceptive properties as well, largely through TRPV-1-dependent mechanisms. Local application of high concentration of capsaicin is used for neuropathic pain and repeated stimulation of TRPV-1 induced an improvement of epigastric pain in irritable bowel syndrome and dyspepsia patients by desensitization of nociceptive pathways. New TRPV-1 agonists are currently under preclinical study and TRPV-1 antagonists are in early clinical development as analgesics. The TRPV-1 pathway might be a novel target for therapeutics in pain sensitivity. PMID:25959004

  18. Hypernatremia-induced vasopressin secretion is not altered in TRPV1-/- rats.

    PubMed

    Tucker, Andrew Blake; Stocker, Sean D

    2016-09-01

    Changes in osmolality or extracellular NaCl concentrations are detected by specialized neurons in the hypothalamus to increase vasopressin (VP) and stimulate thirst. Recent in vitro evidence suggests this process is mediated by an NH2-terminal variant of the transient receptor potential vanilloid type 1 (TRPV1) channel expressed by osmosensitive neurons of the lamina terminalis and vasopressinergic neurons of the supraoptic nucleus. The present study tested this hypothesis in vivo by analysis of plasma VP levels during acute hypernatremia in awake control and TRPV1(-/-) rats. TRPV1(-/-) rats were produced by a Zinc-finger-nuclease 2-bp deletion in exon 13. Intravenous injection of the TRPV1 agonist capsaicin produced hypotension and bradycardia in control rats, but this response was absent in TRPV1(-/-) rats. Infusion of 2 M NaCl (1 ml/h iv) increased plasma osmolality, electrolytes, and VP levels in both control and TRPV1(-/-) rats. However, plasma VP levels did not differ between strains at any time. Furthermore, a linear regression between plasma VP versus osmolality revealed a significant correlation in both control and TRPV1(-/-) rats, but the slope of the regression lines was not attenuated in TRPV1(-/-) versus control rats. Hypotension produced by intravenous injection of minoxidil decreased blood pressure and increased plasma VP levels similarly in both groups. Finally, both treatments stimulated thirst; however, cumulative water intakes in response to hypernatremia or hypotension were not different between control and TRPV1(-/-) rats. These findings suggest that TRPV1 channels are not necessary for VP secretion and thirst stimulated by hypernatremia. PMID:27335281

  19. Distinct properties of Ca2+-calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel

    SciTech Connect

    Lau, Sze-Yi; Procko, Erik; Gaudet, Rachelle

    2012-11-01

    Transient receptor potential (TRP) vanilloid 1 (TRPV1) is a molecular pain receptor belonging to the TRP superfamily of nonselective cation channels. As a polymodal receptor, TRPV1 responds to heat and a wide range of chemical stimuli. The influx of calcium after channel activation serves as a negative feedback mechanism leading to TRPV1 desensitization. The cellular calcium sensor calmodulin (CaM) likely participates in the desensitization of TRPV1. Two CaM-binding sites are identified in TRPV1: the N-terminal ankyrin repeat domain (ARD) and a short distal C-terminal (CT) segment. Here, we present the crystal structure of calcium-bound CaM (Ca2+–CaM) in complex with the TRPV1-CT segment, determined to 1.95-Å resolution. The two lobes of Ca2+–CaM wrap around a helical TRPV1-CT segment in an antiparallel orientation, and two hydrophobic anchors, W787 and L796, contact the C-lobe and N-lobe of Ca2+–CaM, respectively. This structure is similar to canonical Ca2+–CaM-peptide complexes, although TRPV1 contains no classical CaM recognition sequence motif. Using structural and mutational studies, we established the TRPV1 C terminus as a high affinity Ca2+–CaM-binding site in both the isolated TRPV1 C terminus and in full-length TRPV1. Although a ternary complex of CaM, TRPV1-ARD, and TRPV1-CT had previously been postulated, we found no biochemical evidence of such a complex. In electrophysiology studies, mutation of the Ca2+–CaM-binding site on TRPV1-ARD abolished desensitization in response to repeated application of capsaicin, whereas mutation of the Ca2+–CaM-binding site in TRPV1-CT led to a more subtle phenotype of slowed and reduced TRPV1 desensitization. In summary, our results show that the TRPV1-ARD is an important mediator of TRPV1 desensitization, whereas TRPV1-CT has higher affinity for CaM and is likely involved in separate regulatory mechanisms.

  20. Effect of chirality and lipophilicity in the functional activity of evodiamine and its analogues at TRPV1 channels

    PubMed Central

    De Petrocellis, Luciano; Schiano Moriello, Aniello; Fontana, Gabriele; Sacchetti, Alessandro; Passarella, Daniele; Appendino, Giovanni; Di Marzo, Vincenzo

    2014-01-01

    Background and Purpose Evodiamine, a racemic quinazolinocarboline alkaloid isolated from the traditional Chinese medicine Evodiae fructus, has been reported to act as an agonist of the transient receptor potential vanilloid type-1 (TRPV1) cation channel both in vitro and in vivo. Evodiamine is structurally different from all known TRPV1 activators, and has significant clinical potential as a thermogenic agent. Nevertheless, the molecular bases for its actions are still poorly understood. Experimental Approach To investigate the structure-activity relationships of evodiamine, the natural racemate was resolved, and a series of 23 synthetic analogues was prepared, using as the end point the intracellular Ca2+ elevation in HEK-293 cells stably overexpressing either the human or the rat recombinant TRPV1. Key Results S-(+) evodiamine was more efficacious and potent than R-(−) evodiamine, and a new potent lead (Evo30) was identified, more potent than the reference TRPV1 agonist, capsaicin. In general, potency and efficacy correlated with the lipophilicity of the analogues. Like other TRPV1 agonists, several synthetic analogues could efficiently desensitize TRPV1 to activation by capsaicin. Conclusions and Implications Evodiamine qualifies as structurally unique lead structure to develop new potent TRPV1 agonists/desensitizers. Linked Articles This article is part of a themed section on the pharmacology of TRP channels. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-10 PMID:23902373

  1. TRPV1 and Endocannabinoids: Emerging Molecular Signals that Modulate Mammalian Vision

    PubMed Central

    Ryskamp, Daniel A.; Redmon, Sarah; Jo, Andrew O.; Križaj, David

    2014-01-01

    Transient Receptor Potential Vanilloid 1 (TRPV1) subunits form a polymodal cation channel responsive to capsaicin, heat, acidity and endogenous metabolites of polyunsaturated fatty acids. While originally reported to serve as a pain and heat detector in the peripheral nervous system, TRPV1 has been implicated in the modulation of blood flow and osmoregulation but also neurotransmission, postsynaptic neuronal excitability and synaptic plasticity within the central nervous system. In addition to its central role in nociception, evidence is accumulating that TRPV1 contributes to stimulus transduction and/or processing in other sensory modalities, including thermosensation, mechanotransduction and vision. For example, TRPV1, in conjunction with intrinsic cannabinoid signaling, might contribute to retinal ganglion cell (RGC) axonal transport and excitability, cytokine release from microglial cells and regulation of retinal vasculature. While excessive TRPV1 activity was proposed to induce RGC excitotoxicity, physiological TRPV1 activity might serve a neuroprotective function within the complex context of retinal endocannabinoid signaling. In this review we evaluate the current evidence for localization and function of TRPV1 channels within the mammalian retina and explore the potential interaction of this intriguing nociceptor with endogenous agonists and modulators. PMID:25222270

  2. Vanilloids selectively sensitize thermal glutamate release from TRPV1 expressing solitary tract afferents.

    PubMed

    Hofmann, Mackenzie E; Andresen, Michael C

    2016-02-01

    Vanilloids, high temperature, and low pH activate the transient receptor potential vanilloid type 1 (TRPV1) receptor. In spinal dorsal root ganglia, co-activation of one of these gating sites on TRPV1 sensitized receptor gating by other modes. Here in rat brainstem slices, we examined glutamate synaptic transmission in nucleus of the solitary tract (NTS) neurons where most cranial primary afferents express TRPV1, but TRPV1 sensitization is unknown. Electrical shocks to the solitary tract (ST) evoked EPSCs (ST-EPSCs). Activation of TRPV1 with capsaicin (100 nM) increased spontaneous EPSCs (sEPSCs) but inhibited ST-EPSCs. High concentrations of the ultra-potent vanilloid resiniferatoxin (RTX, 1 nM) similarly increased sEPSC rates but blocked ST-EPSCs. Lowering the RTX concentration to 150 pM modestly increased the frequency of the sEPSCs without causing failures in the evoked ST-EPSCs. The sEPSC rate increased with raising bath temperature to 36 °C. Such thermal responses were larger in 150 pM RTX, while the ST-EPSCs remained unaffected. Vanilloid sensitization of thermal responses persisted in TTX but was blocked by the TRPV1 antagonist capsazepine. Our results demonstrate that multimodal activation of TRPV1 facilitates sEPSC responses in more than the arithmetic sum of the two activators, i.e. co-activation sensitizes TRPV1 control of spontaneous glutamate release. Since action potential evoked glutamate release is unaltered, the work provides evidence for cooperativity in gating TRPV1 plus a remarkable separation of calcium mechanisms governing the independent vesicle pools responsible for spontaneous and evoked release at primary afferents in the NTS. PMID:26471418

  3. Activation of transient receptor potential vanilloid-1 (TRPV1) influences how retinal ganglion cell neurons respond to pressure-related stress

    PubMed Central

    Sappington, Rebecca M; Sidorova, Tatiana; Ward, Nicholas J; Chakravarthy, Rohini; Ho, Karen W; Calkins, David J

    2015-01-01

    Our recent studies implicate the transient receptor potential vanilloid-1 (TRPV1) channel as a mediator of retinal ganglion cell (RGC) function and survival. With elevated pressure in the eye, TRPV1 increases in RGCs, supporting enhanced excitability, while Trpv1 -/- accelerates RGC degeneration in mice. Here we find TRPV1 localized in monkey and human RGCs, similar to rodents. Expression increases in RGCs exposed to acute changes in pressure. In retinal explants, contrary to our animal studies, both Trpv1 -/- and pharmacological antagonism of the channel prevented pressure-induced RGC apoptosis, as did chelation of extracellular Ca2+. Finally, while TRPV1 and TRPV4 co-localize in some RGC bodies and form a protein complex in the retina, expression of their mRNA is inversely related with increasing ocular pressure. We propose that TRPV1 activation by pressure-related insult in the eye initiates changes in expression that contribute to a Ca2+-dependent adaptive response to maintain excitatory signaling in RGCs. PMID:25713995

  4. The hypothermic response to bacterial lipopolysaccharide critically depends on brain CB1, but not CB2 or TRPV1, receptors

    PubMed Central

    Steiner, Alexandre A; Molchanova, Alla Y; Dogan, M Devrim; Patel, Shreya; Pétervári, Erika; Balaskó, Márta; Wanner, Samuel P; Eales, Justin; Oliveira, Daniela L; Gavva, Narender R; Almeida, M Camila; Székely, Miklós; Romanovsky, Andrej A

    2011-01-01

    Abstract Hypothermia occurs in the most severe cases of systemic inflammation, but the mechanisms involved are poorly understood. This study evaluated whether the hypothermic response to bacterial lipopolysaccharide (LPS) is modulated by the endocannabinoid anandamide (AEA) and its receptors: cannabinoid-1 (CB1), cannabinoid-2 (CB2) and transient receptor potential vanilloid-1 (TRPV1). In rats exposed to an ambient temperature of 22°C, a moderate dose of LPS (25–100 μg kg−1i.v.) induced a fall in body temperature with a nadir at ∼100 min postinjection. This response was not affected by desensitization of intra-abdominal TRPV1 receptors with resiniferatoxin (20 μg kg−1i.p.), by systemic TRPV1 antagonism with capsazepine (40 mg kg−1i.p.), or by systemic CB2 receptor antagonism with SR144528 (1.4 mg kg−1i.p.). However, CB1 receptor antagonism by rimonabant (4.6 mg kg−1i.p.) or SLV319 (15 mg kg−1i.p.) blocked LPS hypothermia. The effect of rimonabant was further studied. Rimonabant blocked LPS hypothermia when administered i.c.v. at a dose (4.6 μg) that was too low to produce systemic effects. The blockade of LPS hypothermia by i.c.v. rimonabant was associated with suppression of the circulating level of tumour necrosis factor-α. In contrast to rimonabant, the i.c.v. administration of AEA (50 μg) enhanced LPS hypothermia. Importantly, i.c.v. AEA did not evoke hypothermia in rats not treated with LPS, thus indicating that AEA modulates LPS-activated pathways in the brain rather than thermoeffector pathways. In conclusion, the present study reveals a novel, critical role of brain CB1 receptors in LPS hypothermia. Brain CB1 receptors may constitute a new therapeutic target in systemic inflammation and sepsis. PMID:21486787

  5. The hypothermic response to bacterial lipopolysaccharide critically depends on brain CB1, but not CB2 or TRPV1, receptors.

    PubMed

    Steiner, Alexandre A; Molchanova, Alla Y; Dogan, M Devrim; Patel, Shreya; Pétervári, Erika; Balaskó, Márta; Wanner, Samuel P; Eales, Justin; Oliveira, Daniela L; Gavva, Narender R; Almeida, M Camila; Székely, Miklós; Romanovsky, Andrej A

    2011-05-01

    Hypothermia occurs in the most severe cases of systemic inflammation, but the mechanisms involved are poorly understood. This study evaluated whether the hypothermic response to bacterial lipopolysaccharide (LPS) is modulated by the endocannabinoid anandamide(AEA) and its receptors: cannabinoid-1 (CB1), cannabinoid-2 (CB2) and transient receptor potential vanilloid-1 (TRPV1). In rats exposed to an ambient temperature of 22◦C, a moderate dose of LPS (25 - 100 μg kg−1 I.V.) induced a fall in body temperature with a nadir at ∼100 minpostinjection. This response was not affected by desensitization of intra-abdominal TRPV1 receptors with resiniferatoxin (20 μg kg - 1 I.P.), by systemic TRPV1 antagonism with capsazepine(40mg kg−1 I.P.), or by systemic CB2 receptor antagonism with SR144528 (1.4 mg kg−1 I.P.).However, CB1 receptor antagonism by rimonabant (4.6mg kg−1 I.P.) or SLV319 (15mg kg−1 I.P.)blocked LPS hypothermia. The effect of rimonabant was further studied. Rimonabant blocked LPS hypothermia when administered I.C.V. at a dose (4.6 μg) that was too low to produce systemic effects. The blockade of LPS hypothermia by I.C.V. rimonabant was associated with suppression of the circulating level of tumour necrosis factor-α. In contrast to rimonabant,the I.C.V. administration of AEA (50 μg) enhanced LPS hypothermia. Importantly, I.C.V. AEAdid not evoke hypothermia in rats not treated with LPS, thus indicating that AEA modulates LPS-activated pathways in the brain rather than thermo effector pathways. In conclusion, the present study reveals a novel, critical role of brain CB1 receptors in LPS hypothermia. Brain CB1 receptors may constitute a new therapeutic target in systemic inflammation and sepsis. PMID:21486787

  6. TRPV1 antagonist capsazepine suppresses 4-AP-induced epileptiform activity in vitro and electrographic seizures in vivo

    PubMed Central

    Gonzalez-Reyes, Luis E.; Ladas, Thomas P.; Chiang, Chia-Chu; Durand, Dominique M.

    2014-01-01

    Transient receptor potential vanilloid 1 (TRPV1) is a cation-permeable ion channel found in the peripheral and central nervous systems. The membrane surface expression of TRPV1 is known to occur in neuronal cell bodies and sensory neuron axons. TRPV1 receptors are also expressed in the hippocampus, the main epileptogenic region in the brain. Although, previous studies implicate TRPV1 channels in the generation of epilepsy, suppression of ongoing seizures by TRPV1 antagonists has not yet been attempted. Here, we evaluate the role of TRPV1 channels in the modulation of epileptiform activity as well as the anti-convulsant properties of capsazepine (CZP), an established TRPV1 competitive antagonist, using in vitro and in vivo models. To this end, we used 4-aminopyridine (4-AP) to trigger seizure-like activity. We found that CZP suppressed 4-AP induced epileptiform activity in vitro (10–100 µM) and in vivo (50 mg/kg s.c.). In contrast, capsaicin enhanced 4-AP induced epileptiform activity in vitro (1–100 µM) and triggered bursting activity in vivo (100 µM dialysis perfusion), which was abolished by the TRPV1 antagonist CZP. To further investigate the mechanisms of TRPV1 modulation, we studied the effect in capcaisin and CPZ on evoked potentials. Capsaicin (1–100 µM) and CZP (10–100 µM) increased and decreased, respectively, the amplitude of extracellular field evoked potentials in a concentration-dependent manner. Additional in vitro studies showed that the effect of the TRPV1 blocker on evoked potentials was similar whether the response was orthodromic or antidromic, suggesting that the effect involves interference with membrane depolarization on cells bodies and axons. The fact that CPZ could act directly on axons was confirmed by decreased amplitude of the compound action potential and by an increased delay of both the antidromic potentials and the axonal response. Histological studies using transgenic mice also show that, in addition to the known neural

  7. ZO-1 and -2 Are Required for TRPV1-Modulated Paracellular Permeability.

    PubMed

    Li, J; Cong, X; Zhang, Y; Xiang, R L; Mei, M; Yang, N Y; Su, Y C; Choi, S; Park, K; Zhang, L W; Wu, L L; Yu, G Y

    2015-12-01

    The tight junction-based paracellular pathway plays an important role in saliva secretion. Zonula occludens (ZO) proteins are submembranous proteins of tight junction complex; however, their function in salivary epithelium is poorly understood. Here, we found that activation of transient receptor potential vanilloid subtype 1 (TRPV1) by capsaicin increased rat saliva secretion both in vivo and ex vivo. Meanwhile, TRPV1 activation enlarged the width of tight junctions between neighboring acinar cells, increased the paracellular flux of 4-kDa fluorescein isothiocyanate (FITC)-dextran in submandibular gland (SMG) tissues, and decreased transepithelial electric resistance (TER) in SMG-C6 cells. ZO-1, -2, and -3 were distributed principally to the apical lateral region of acinar cells in SMG tissues and continuously encircled the peripheries of SMG-C6 cells in the untreated condition. TRPV1 activation obviously diminished ZO-1 and -2 staining, but not ZO-3 or β-catenin, at the cell-cell contacts ex vivo and in vitro. Moreover, in untreated SMG-C6 cells, ZO-1 and -2 single or double knockdown by small interfering RNA (siRNA) increased the paracellular flux of 4-kDa FITC-dextran. In capsaicin-treated cells, ZO-1 and -2 single or double knockdown abolished, whereas their re-expression restored, the capsaicin-induced increase in paracellular permeability. Furthermore, TRPV1 activation increased RhoA activity, and inhibition of either RhoA or Rho kinase (ROCK) abolished the capsaicin-induced TER decrease as well as ZO-1 and -2 redistribution. These results indicate that ZO-1 and -2 play crucial roles in both basal salivary epithelial barrier function and TRPV1-modulated paracellular transport. RhoA-ROCK signaling pathway is responsible for TRPV1-modulated paracellular permeability as well as ZO-1 and -2 redistribution. PMID:26464396

  8. Biphasic modulation by mGlu5 receptors of TRPV1-mediated intracellular calcium elevation in sensory neurons contributes to heat sensitivity

    PubMed Central

    Masuoka, T; Nakamura, T; Kudo, M; Yoshida, J; Takaoka, Y; Kato, N; Ishibashi, T; Imaizumi, N; Nishio, M

    2015-01-01

    Background and Purpose Elevation of glutamate, an excitatory amino acid, during inflammation and injury plays a crucial role in the reception and transmission of sensory information via ionotropic and metabotropic receptors. This study aimed to investigate the mechanisms underlying the biphasic effects of metabotropic glutamate mGlu5 receptor activation on responses to noxious heat. Experimental Approach We assessed the effects of intraplantar quisqualate, a non-selective glutamate receptor agonist, on heat and mechanical pain behaviours in mice. In addition, the effects of quisqualate on the intracellular calcium response and on membrane currents mediated by TRPV1 channels, were examined in cultured dorsal root ganglion neurons from mice. Key Results Activation of mGlu5 receptors in hind paw transiently increased, then decreased, the response to noxious heat. In sensory neurons, activation of mGlu5 receptors potentiated TRPV1-mediated intracellular calcium elevation, while terminating activation of mGlu5 receptors depressed it. TRPV1-induced currents were potentiated by activation of mGlu5 receptors under voltage clamp conditions and these disappeared after washout. However, voltage-gated calcium currents were inhibited by the mGlu5 receptor agonist, even after washout. Conclusions and Implications These results suggest that, in sensory neurons, mGlu5 receptors biphasically modulate TRPV1-mediated intracellular calcium response via transient potentiation of TRPV1 channel-induced currents and persistent inhibition of voltage-gated calcium currents, contributing to heat hyper- and hypoalgesia. PMID:25297838

  9. A- Kinase Anchoring Protein 150 Controls Protein Kinase C-mediated Phosphorylation and Sensitization of TRPV1

    PubMed Central

    Jeske, Nathaniel A.; Patwardhan, Amol M.; Ruparel, Nikita B.; Akopian, Armen N; Shapiro, Mark S.; Henry, Michael A.

    2009-01-01

    Post-translational modifications on various receptor proteins have significant effects on receptor activation. For the Transient Receptor Potential family V type 1 (TRPV1) receptor, phosphorylation of certain serine/threonine amino acid residues sensitizes the receptor to activation by capsaicin and heat. Although Protein Kinase C (PKC) phosphorylates TRPV1 on certain serine/threonine residues, it is not completely understood how PKC functionally associates with TRPV1. Recent studies have reported that the A-kinase Anchoring Protein 150 (AKAP150) mediates PKA phosphorylation of TRPV1 in several nociceptive models. Here, we demonstrate that AKAP150 also mediates PKC-directed phosphorylation and sensitization of TRPV1. In cultured rat trigeminal ganglia, immunocytochemical analyses demonstrate co-localization of AKAP150 and PKC isoforms α, δ, ε, and γ in TRPV1-positive neurons. Additional biochemical evidence supports immunocytochemical results, indicating that AKAP150 preferentially associates with certain PKC isoforms in rat trigeminal ganglia neurons. Employing siRNA-mediated knock-down of AKAP150 expression, we demonstrate that PKC-mediated phosphorylation of TRPV1 and sensitization to a capsaicin response is dependent upon functional expression of the AKAP150 scaffolding protein. Furthermore, PKC-induced sensitization to a thermal stimulus is abrogated in AKAP150 knock-out animals relative to wild-type. Collectively, results from these studies indicate that the AKAP150 scaffolding protein functionally modulates PKC-mediated phosphorylation and sensitization of the TRPV1 receptor in rat sensory neurons, suggesting the scaffolding protein to be an integral regulator of peripheral inflammatory hyperalgesia. PMID:19767149

  10. Activation of endogenous TRPV1 fails to induce overstimulation-based cytotoxicity in breast and prostate cancer cells but not in pain-sensing neurons.

    PubMed

    Pecze, László; Jósvay, Katalin; Blum, Walter; Petrovics, György; Vizler, Csaba; Oláh, Zoltán; Schwaller, Beat

    2016-08-01

    Vanilloids including capsaicin and resiniferatoxin are potent transient receptor potential vanilloid type 1 (TRPV1) agonists. TRPV1 overstimulation selectively ablates capsaicin-sensitive sensory neurons in animal models in vivo. The cytotoxic mechanisms are based on strong Na(+) and Ca(2+) influx via TRPV1 channels, which leads to mitochondrial Ca(2+) accumulation and necrotic cell swelling. Increased TRPV1 expression levels are also observed in breast and prostate cancer and derived cell lines. Here, we examined whether potent agonist-induced overstimulation mediated by TRPV1 might represent a means for the eradication of prostate carcinoma (PC-3, Du 145, LNCaP) and breast cancer (MCF7, MDA-MB-231, BT-474) cells in vitro. While rat sensory neurons were highly vanilloid-sensitive, normal rat prostate epithelial cells were resistant in vivo. We found TRPV1 to be expressed in all cancer cell lines at mRNA and protein levels, yet protein expression levels were significantly lower compared to sensory neurons. Treatment of all human carcinoma cell lines with capsaicin didn't lead to overstimulation cytotoxicity in vitro. We assume that the low vanilloid-sensitivity of prostate and breast cancer cells is associated with low expression levels of TRPV1, since ectopic TRPV1 expression rendered them susceptible to the cytotoxic effect of vanilloids evidenced by plateau-type Ca(2+) signals, mitochondrial Ca(2+) accumulation and Na(+)- and Ca(2+)-dependent membrane disorganization. Moreover, long-term monitoring revealed that merely the ectopic expression of TRPV1 stopped cell proliferation and often induced apoptotic processes via strong activation of caspase-3 activity. Our results indicate that specific targeting of TRPV1 function remains a putative strategy for cancer treatment. PMID:27180305

  11. Propofol Restores Transient Receptor Potential Vanilloid Receptor Subtype-1 Sensitivity via Activation of Transient Receptor Potential Ankyrin Receptor Subtype-1 in Sensory Neurons

    PubMed Central

    Zhang, Hongyu; Wickley, Peter J.; Sinha, Sayantani; Bratz, Ian N.; Damron, Derek S.

    2011-01-01

    Background Crosstalk between peripheral nociceptors belonging to the transient receptor potential vanilloid receptor subtype-1 (TRPV1) and ankyrin subtype-1 (TRPA1) family has recently been demonstrated. Moreover, the intravenous anesthetic propofol has been shown to directly activate TRPA1 receptors, and indirectly restore sensitivity of TRPV1 receptors in dorsal root ganglion (DRG) sensory neurons. Our objective was to determine the extent to which TRPA1 activation is involved in mediating the propofol-induced restoration of TRPV1 sensitivity. Methods Mouse DRG neurons were isolated by enzymatic dissociation and grown for 24 h. F-11 cells were transfected with complementary DNA for both TRPV1 and TRPA1 or TRPV1 only. Intracellular Ca2+ concentration was measured in individual cells via fluorescence microscopy. Following TRPV1 de-sensitization with capsaicin (100 nM), cells were treated with propofol (1, 5 and 10 μM) alone, propofol in the presence of the TRPA1 antagonist, HC-030031 (0.5 μM) or the TRPA1 agonist, Allyl isothiocyanate (AITC, 100 μM) and capsaicin was then reapplied. Results In DRG neurons that contain both TRPV1 and TRPA1, propofol and AITC restored TRPV1 sensitivity. However, in DRG neurons containing only TRPV1 receptors, exposure to propofol or AITC following de-sensitization did not restore capsaicin-induced TRPV1 sensitivity. Similarly, in F-11 cells transfected with both TRPV1 and TRPA1, propofol and AITC restored TRPV1 sensitivity. However, in F-11 cells transfected with TRPV1 only, neither propofol nor AITC were capable of restoring TRPV1 sensitivity. Conclusions These data demonstrate that propofol restores TRPV1 sensitivity in primary DRG neurons and in cultured F-11 cells transfected with both the TRPV1 and TRPA1 receptors via a TRPA1-dependent process. Propofol’s effects on sensory neurons may be clinically important and contribute to peripheral sensitization to nociceptive stimuli in traumatized tissue. PMID:21364461

  12. Facilitation of TRPV4 by TRPV1 is required for itch transmission in some sensory neuron populations.

    PubMed

    Kim, Seungil; Barry, Devin M; Liu, Xian-Yu; Yin, Shijin; Munanairi, Admire; Meng, Qing-Tao; Cheng, Wei; Mo, Ping; Wan, Li; Liu, Shen-Bin; Ratnayake, Kasun; Zhao, Zhong-Qiu; Gautam, Narasimhan; Zheng, Jie; Karunarathne, W K Ajith; Chen, Zhou-Feng

    2016-01-01

    The transient receptor potential channels (TRPs) respond to chemical irritants and temperature. TRPV1 responds to the itch-inducing endogenous signal histamine, and TRPA1 responds to the itch-inducing chemical chloroquine. We showed that, in sensory neurons, TRPV4 is important for both chloroquine- and histamine-induced itch and that TRPV1 has a role in chloroquine-induced itch. Chloroquine-induced scratching was reduced in mice in which TRPV1 was knocked down or pharmacologically inhibited. Both TRPV4 and TRPV1 were present in some sensory neurons. Pharmacological blockade of either TRPV4 or TRPV1 significantly attenuated the Ca(2+) response of sensory neurons exposed to histamine or chloroquine. Knockout of Trpv1 impaired Ca(2+) responses and reduced scratching behavior evoked by a TRPV4 agonist, whereas knockout of Trpv4 did not alter TRPV1-mediated capsaicin responses. Electrophysiological analysis of human embryonic kidney (HEK) 293 cells coexpressing TRPV4 and TRPV1 revealed that the presence of both channels enhanced the activation kinetics of TRPV4 but not of TRPV1. Biochemical and biophysical studies suggested a close proximity between TRPV4 and TRPV1 in dorsal root ganglion neurons and in cultured cells. Thus, our studies identified TRPV4 as a channel that contributes to both histamine- and chloroquine-induced itch and indicated that the function of TRPV4 in itch signaling involves TRPV1-mediated facilitation. TRP facilitation through the formation of heteromeric complexes could be a prevalent mechanism by which the vast array of somatosensory information is encoded in sensory neurons. PMID:27436359

  13. The Effect of Capsaicin on Salivary Gland Dysfunction.

    PubMed

    Shin, Yong-Hwan; Kim, Jin Man; Park, Kyungpyo

    2016-01-01

    Capsaicin (trans-8-methyl-N-vanilyl-6-nonenamide) is a unique alkaloid isolated from hot chili peppers of the capsicum family. Capsaicin is an agonist of transient receptor potential vanilloid subtype 1 (TRPV1), which is expressed in nociceptive sensory neurons and a range of secretory epithelia, including salivary glands. Capsaicin has analgesic and anti-inflammatory properties in sensory neurons. Recently, increasing evidence has indicated that capsaicin also affects saliva secretion and inflammation in salivary glands. Applying capsaicin increases salivary secretion in human and animal models. Capsaicin appears to increase salivation mainly by modulating the paracellular pathway in salivary glands. Capsaicin activates TRPV1, which modulates the permeability of tight junctions (TJ) by regulating the expression and function of putative intercellular adhesion molecules in an ERK (extracelluar signal-regulated kinase) -dependent manner. Capsaicin also improved dysfunction in transplanted salivary glands. Aside from the secretory effects of capsaicin, it has anti-inflammatory effects in salivary glands. The anti-inflammatory effect of capsaicin is, however, not mediated by TRPV1, but by inhibition of the NF-κB pathway. In conclusion, capsaicin might be a potential drug for alleviating dry mouth symptoms and inflammation of salivary glands. PMID:27347918

  14. Tyrosine Residue in the TRPV1 Vanilloid Binding Pocket Regulates Deactivation Kinetics.

    PubMed

    Kumar, Rakesh; Hazan, Adina; Basu, Arijit; Zalcman, Nomi; Matzner, Henry; Priel, Avi

    2016-06-24

    Vanilloids are pain evoking molecules that serve as ligands of the "heat and capsaicin receptor" TRPV1. Binding of either endogenous or exogenous vanilloids evokes channel and subsequent neuronal activation, leading to pain sensation. Despite its pivotal physiological role, the molecular basis of TRPV1 activation and deactivation is not fully understood. The highly conserved tyrosine in position 511 (Tyr(511)) of the rat TRPV1 (rTRPV1) was the first residue to be identified as a necessary participant in the vanilloid-mediated response. rTRPV1 cryo-EM structures implicated rotation of this residue in the vanilloids bound state. Therefore, we hypothesize that the rTRPV1 Tyr(511) residue entraps vanilloids in their binding site, prolonging channel activity. To test our hypothesis, we generated an array of rTRPV1 mutants, containing the whole spectrum of Tyr(511) substitutions, and tested their response to both exo- and endovanilloids. Our data show that only substitutions of Tyr(511) to aromatic amino acids were able to mimic, albeit partially, the vanilloid-evoked activation pattern of the wt receptor. Although these substitutions reduced the channel sensitivity to vanilloids, a maximal open-channel lifetime could be achieved. Moreover, whereas their current activation rate remains intact, receptors with Tyr(511) substitutions exhibited a faster current deactivation. Our findings therefore suggest that the duration of channel activity evoked by vanilloids is regulated by the interaction between Tyr(511) and the agonist. To conclude, we suggest that Tyr(511)-mediated anchoring of vanilloids in their binding pocket is pivotal for TRPV1 activation and subsequent pain sensation. PMID:27143360

  15. Functionally important amino acid residues in the transient receptor potential vanilloid 1 (TRPV1) ion channel – an overview of the current mutational data

    PubMed Central

    2013-01-01

    This review aims to create an overview of the currently available results of site-directed mutagenesis studies on transient receptor potential vanilloid type 1 (TRPV1) receptor. Systematization of the vast number of data on the functionally important amino acid mutations of TRPV1 may provide a clearer picture of this field, and may promote a better understanding of the relationship between the structure and function of TRPV1. The review summarizes information on 112 unique mutated sites along the TRPV1, exchanged to multiple different residues in many cases. These mutations influence the effect or binding of different agonists, antagonists, and channel blockers, alter the responsiveness to heat, acid, and voltage dependence, affect the channel pore characteristics, and influence the regulation of the receptor function by phosphorylation, glycosylation, calmodulin, PIP2, ATP, and lipid binding. The main goal of this paper is to publish the above mentioned data in a form that facilitates in silico molecular modelling of the receptor by promoting easier establishment of boundary conditions. The better understanding of the structure-function relationship of TRPV1 may promote discovery of new, promising, more effective and safe drugs for treatment of neurogenic inflammation and pain-related diseases and may offer new opportunities for therapeutic interventions. PMID:23800232

  16. A painful link between the TRPV1 channel and lysophosphatidic acid.

    PubMed

    Morales-Lázaro, Sara L; Rosenbaum, Tamara

    2015-03-15

    The Transient Receptor Potential Vanilloid 1 (TRPV1) ion channel is expressed mainly by sensory neurons that detect noxious stimuli from the environment such as high temperatures and pungent compounds (such as allicin and capsaicin) and has been extensively linked to painful and inflammatory processes. This extraordinary protein also responds to endogenous stimuli among which we find molecules of a lipidic nature. We recently described that lysophosphatidic acid (LPA), a bioactive lysophospholipid linked to the generation and maintenance of pain, can directly activate TRPV1 and produce pain by binding to the channels' C-terminal region, specifically to residue K710. In an effort to further understand how activation of TRPV1 is achieved by this negatively-charged lipid, we used several synthetic and naturally-occurring lipids to determine the structural requirements that need to be met by these charged lipids in order to produce the activation of TRPV1. In this review, we detail the findings obtained by other research groups and our own on the field of TRPV1-regulation by negatively-charged lipids and discuss the possible therapeutic relevance of these findings on the basis of the role of TRPV1 in pathophysiological processes. PMID:25445434

  17. Repeated dosing of ABT-102, a potent and selective TRPV1 antagonist, enhances TRPV1-mediated analgesic activity in rodents, but attenuates antagonist-induced hyperthermia.

    PubMed

    Honore, Prisca; Chandran, Prasant; Hernandez, Gricelda; Gauvin, Donna M; Mikusa, Joseph P; Zhong, Chengmin; Joshi, Shailen K; Ghilardi, Joseph R; Sevcik, Molly A; Fryer, Ryan M; Segreti, Jason A; Banfor, Patricia N; Marsh, Kennan; Neelands, Torben; Bayburt, Erol; Daanen, Jerome F; Gomtsyan, Arthur; Lee, Chih-Hung; Kort, Michael E; Reilly, Regina M; Surowy, Carol S; Kym, Philip R; Mantyh, Patrick W; Sullivan, James P; Jarvis, Michael F; Faltynek, Connie R

    2009-03-01

    Transient receptor potential vanilloid type 1 (TRPV1) is a ligand-gated ion channel that functions as an integrator of multiple pain stimuli including heat, acid, capsaicin and a variety of putative endogenous lipid ligands. TRPV1 antagonists have been shown to decrease inflammatory pain in animal models and to produce limited hyperthermia at analgesic doses. Here, we report that ABT-102, which is a potent and selective TRPV1 antagonist, is effective in blocking nociception in rodent models of inflammatory, post-operative, osteoarthritic, and bone cancer pain. ABT-102 decreased both spontaneous pain behaviors and those evoked by thermal and mechanical stimuli in these models. Moreover, we have found that repeated administration of ABT-102 for 5-12 days increased its analgesic activity in models of post-operative, osteoarthritic, and bone cancer pain without an associated accumulation of ABT-102 concentration in plasma or brain. Similar effects were also observed with a structurally distinct TRPV1 antagonist, A-993610. Although a single dose of ABT-102 produced a self-limiting increase in core body temperature that remained in the normal range, the hyperthermic effects of ABT-102 effectively tolerated following twice-daily dosing for 2 days. Therefore, the present data demonstrate that, following repeated administration, the analgesic activity of TRPV1 receptor antagonists is enhanced, while the associated hyperthermic effects are attenuated. The analgesic efficacy of ABT-102 supports its advancement into clinical studies. PMID:19135797

  18. Ethanol attenuation of long term depression in the nucleus accumbens can be overcome by activation of TRPV1 receptors

    PubMed Central

    Renteria, Rafael; Jeanes, Zachary M.; Morrisett, Richard A.

    2014-01-01

    Background Altered expression of synaptic plasticity within the nucleus accumbens (NAc) constitutes a critical neuroadaptive response to ethanol and other drugs of abuse. We have previously reported that NMDA receptor-dependent long-term depression (LTD) is markedly affected by chronic intermittent ethanol exposure in vivo; however, endocannabinoid (eCB)-dependent synaptic depression, despite being very well-documented in the dorsal striatum, is much less well understood in the NAc. Methods Whole cell patch clamp electrophysiology was used to investigate interactions between these different plasticity-induction systems. Excitatory postsynaptic currents (EPSCs) were measured in the NAc shell and NMDAR-LTD was induced by a pairing protocol (500 stimuli @ 1 Hz stimulation (LFS) paired with postsynaptic depolarization to −50 mV). AM251, a CB1 receptor antagonist, was used to determine whether this form of LTD is modulated by eCBs. To determine the effect of ethanol on a purely eCB-dependent response in the NAc, depolarization-induced suppression of excitation (DSE) was used in the presence of 40 mM ethanol. Finally, we determined whether the enhancement of eCB signaling with URB597, a fatty acid amide hydrolase inhibitor, and AM404, an anandamide reuptake inhibitor would also modulate LFS LTD in the presence of NMDA-receptor blockade or ethanol. Results In the presence of AM251, the LFS pairing protocol resulted in NMDA receptor-dependent long-term potentiation (LTP) that was blocked with either ethanol or DL-APV. We also found that DSE in the NAc shell was blocked by AM251 and suppressed by ethanol. Enhanced eCB signaling rescued NAc LTD expression in the presence of ethanol through a distinct mechanism requiring activation of TRPV1 receptors. Conclusion Ethanol modulation of synaptic plasticity in the NAc is dependent upon a complex interplay between NMDA receptors, eCBs and TRPV1 receptors. These findings demonstrate a novel form of TRPV1-dependent LTD in the NAc

  19. TRPV1 Activation Exacerbates Hypoxia/Reoxygenation-Induced Apoptosis in H9C2 Cells via Calcium Overload and Mitochondrial Dysfunction

    PubMed Central

    Sun, Zewei; Han, Jie; Zhao, Wenting; Zhang, Yuanyuan; Wang, Shuai; Ye, Lifang; Liu, Tingting; Zheng, Liangrong

    2014-01-01

    Transient potential receptor vanilloid 1 (TRPV1) channels, which are expressed on sensory neurons, elicit cardioprotective effects during ischemia reperfusion injury by stimulating the release of neuropeptides, namely calcitonin gene-related peptide (CGRP) and substance P (SP). Recent studies show that TRPV1 channels are also expressed on cardiomyocytes and can exacerbate air pollutant-induced apoptosis. However, whether these channels present on cardiomyocytes directly modulate cell death and survival pathways during hypoxia/reoxygenation (H/R) injury remains unclear. In the present study, we investigated the role of TRPV1 in H/R induced apoptosis of H9C2 cardiomyocytes. We demonstrated that TRPV1 was indeed expressed in H9C2 cells, and activated by H/R injury. Although neuropeptide release caused by TRPV1 activation on sensory neurons elicits a cardioprotective effect, we found that capsaicin (CAP; a TRPV1 agonist) treatment of H9C2 cells paradoxically enhanced the level of apoptosis by increasing intracellular calcium and mitochondrial superoxide levels, attenuating mitochondrial membrane potential, and inhibiting mitochondrial biogenesis (measured by the expression of ATP synthase β). In contrast, treatment of cells with capsazepine (CPZ; a TRPV1 antagonist) or TRPV1 siRNA attenuated H/R induced-apoptosis. Furthermore, CAP and CPZ treatment revealed a similar effect on cell viability and mitochondrial superoxide production in primary cardiomyocytes. Finally, using both CGRP8–37 (a CGRP receptor antagonist) and RP67580 (a SP receptor antagonist) to exclude the confounding effects of neuropeptides, we confirmed aforementioned detrimental effects as TRPV1−/− mouse hearts exhibited improved cardiac function during ischemia/reperfusion. In summary, direct activation of TRPV1 in myocytes exacerbates H/R-induced apoptosis, likely through calcium overload and associated mitochondrial dysfunction. Our study provides a novel understanding of the role of myocyte

  20. The Cancer Chemotherapeutic Paclitaxel Increases Human and Rodent Sensory Neuron Responses to TRPV1 by Activation of TLR4

    PubMed Central

    Li, Yan; Adamek, Pavel; Zhang, Haijun; Tatsui, Claudio Esteves; Rhines, Laurence D.; Mrozkova, Petra; Li, Qin; Kosturakis, Alyssa K.; Cassidy, Ryan M.; Harrison, Daniel S.; Cata, Juan P.; Sapire, Kenneth; Zhang, Hongmei; Kennamer-Chapman, Ross M.; Jawad, Abdul Basit; Ghetti, Andre; Yan, Jiusheng; Palecek, Jiri

    2015-01-01

    Peripheral neuropathy is dose limiting in paclitaxel cancer chemotherapy and can result in both acute pain during treatment and chronic persistent pain in cancer survivors. The hypothesis tested was that paclitaxel produces these adverse effects at least in part by sensitizing transient receptor potential vanilloid subtype 1 (TRPV1) through Toll-like receptor 4 (TLR4) signaling. The data show that paclitaxel-induced behavioral hypersensitivity is prevented and reversed by spinal administration of a TRPV1 antagonist. The number of TRPV1+ neurons is increased in the dorsal root ganglia (DRG) in paclitaxel-treated rats and is colocalized with TLR4 in rat and human DRG neurons. Cotreatment of rats with lipopolysaccharide from the photosynthetic bacterium Rhodobacter sphaeroides (LPS-RS), a TLR4 inhibitor, prevents the increase in numbers of TRPV1+ neurons by paclitaxel treatment. Perfusion of paclitaxel or the archetypal TLR4 agonist LPS activated both rat DRG and spinal neurons directly and produced acute sensitization of TRPV1 in both groups of cells via a TLR4-mediated mechanism. Paclitaxel and LPS sensitize TRPV1 in HEK293 cells stably expressing human TLR4 and transiently expressing human TRPV1. These physiological effects also are prevented by LPS-RS. Finally, paclitaxel activates and sensitizes TRPV1 responses directly in dissociated human DRG neurons. In summary, TLR4 was activated by paclitaxel and led to sensitization of TRPV1. This mechanism could contribute to paclitaxel-induced acute pain and chronic painful neuropathy. SIGNIFICANCE STATEMENT In this original work, it is shown for the first time that paclitaxel activates peripheral sensory and spinal neurons directly and sensitizes these cells to transient receptor potential vanilloid subtype 1 (TRPV1)-mediated capsaicin responses via Toll-like receptor 4 (TLR4) in multiple species. A direct functional interaction between TLR4 and TRPV1 is shown in rat and human dorsal root ganglion neurons, TLR4/TRPV1

  1. Activation of CB1 inhibits NGF-induced sensitization of TRPV1 in adult mouse afferent neurons

    PubMed Central

    Wang, Zun-Yi; McDowell, Thomas; Wang, Peiqing; Alvarez, Roxanne; Gomez, Timothy; Bjorling, Dale E.

    2015-01-01

    Transient receptor potential vanilloid 1 (TRPV1)-containing afferent neurons convey nociceptive signals and play an essential role in pain sensation. Exposure to nerve growth factor (NGF) rapidly increases TRPV1 activity (sensitization). In the present study, we investigated whether treatment with the selective cannabinoid receptor 1 (CB1) agonist arachidonyl-2'-chloroethylamide (ACEA) affects NGF-induced sensitization of TRPV1 in adult mouse dorsal root ganglion (DRG) afferent neurons. We found that CB1, NGF receptor tyrosine kinase A (trkA), and TRPV1 are present in cultured adult mouse small- to medium-sized afferent neurons and treatment with NGF (100 ng/ml) for 30 minutes significantly increased the number of neurons that responded to capsaicin (as indicated by increased intracellular Ca2+ concentration). Pretreatment with the CB1 agonist ACEA (10 nM) inhibited the NGF-induced response, and this effect of ACEA was reversed by a selective CB1 antagonist. Further, pretreatment with ACEA inhibited NGF-induced phosphorylation of AKT. Blocking PI3 kinase activity also attenuated the NGF-induced increase in the number of neurons that responded to capsaicin. Our results indicate that the analgesic effect of CB1 activation may in part be due to inhibition of NGF-induced sensitization of TRPV1 and also that the effect of CB1 activation is at least partly mediated by attenuation of NGF-induced increased PI3 signaling. PMID:25088915

  2. Inhibition of TRPV1 channels enables long-term potentiation in the entorhinal cortex.

    PubMed

    Banke, Tue G

    2016-04-01

    The transient receptor potential vanilloid 1 (TRPV1) channel is a non-selective cation channel that is mainly found in nociceptive neurons of the peripheral nervous system; however, these channels have also been located within the CNS, including the entorhinal cortex. Whole-cell patch-clamp recordings of principal entorhinal cortex (EC) layers II/III neurons revealed that evoked inhibitory postsynaptic currents were depressed by application of the TRPV1 agonist capsaicin (CAP), accompanied by a change in the pair-pulse ratio (PPR). In addition, recordings of miniature inhibitory postsynaptic currents (mIPSCs) revealed that inter-event intervals but not amplitude were decreased in wild-type (WT) after application of CAP. This suggests that TRPV1 channels are functional in the entorhinal cortex and are located on inhibitory neurons with their axonal arborization within layers II/III. In order to study TRPV1 channels and their involvement in long-term potentiation (LTP) induction in a more intact circuit, extracellular field potential recordings were performed in EC layers II/III. It was found that activated TRPV1 channels preclude induction of long-term potentiation. In sharp contrast, clear LTP was observed when antagonizing TRPV1 channels or recording from TRPV1 knock-out mice. Thus, these results suggests that signaling through activating inhibitory presynaptic TRPV1 channels represents a novel mechanism by which a shift in feed-forward inhibition of layers II/III cortical principal neurons prompt changes in synaptic strength and thereby contribute to a change of information storage within the brain. PMID:26729265

  3. Divalent cations potentiate TRPV1 channel by lowering the heat activation threshold

    PubMed Central

    Cao, Xu; Ma, Linlin; Yang, Fan

    2014-01-01

    Transient receptor potential vanilloid type 1 (TRPV1) channel responds to a wide spectrum of physical and chemical stimuli. In doing so, it serves as a polymodal cellular sensor for temperature change and pain. Many chemicals are known to strongly potentiate TRPV1 activation, though how this is achieved remains unclear. In this study we investigated the molecular mechanism underlying the gating effects of divalent cations Mg2+ and Ba2+. Using a combination of fluorescence imaging and patch-clamp analysis, we found that these cations potentiate TRPV1 gating by most likely promoting the heat activation process. Mg2+ substantially lowers the activation threshold temperature; as a result, a significant fraction of channels are heat-activated at room temperature. Although Mg2+ also potentiates capsaicin- and voltage-dependent activation, these processes were found either to be not required (in the case of capsaicin) or insufficient (in the case of voltage) to mediate the activating effect. In support of a selective effect on heat activation, Mg2+ and Ba2+ cause a Ca2+-independent desensitization that specifically prevents heat-induced channel activation but does not prevent capsaicin-induced activation. These results can be satisfactorily explained within an allosteric gating framework in which divalent cations strongly promote the heat-dependent conformational change or its coupling to channel activation, which is further coupled to the voltage- and capsaicin-dependent processes. PMID:24344247

  4. Breathtaking TRP channels: TRPA1 and TRPV1 in airway chemosensation and reflex control.

    PubMed

    Bessac, Bret F; Jordt, Sven-Eric

    2008-12-01

    New studies have revealed an essential role for TRPA1, a sensory neuronal TRP ion channel, in airway chemosensation and inflammation. TRPA1 is activated by chlorine, reactive oxygen species, and noxious constituents of smoke and smog, initiating irritation and airway reflex responses. Together with TRPV1, the capsaicin receptor, TRPA1 may contribute to chemical hypersensitivity, chronic cough, and airway inflammation in asthma, COPD, and reactive airway dysfunction syndrome. PMID:19074743

  5. Dissecting the role of TRPV1 in detecting multiple trigeminal irritants in three behavioral assays for sensory irritation

    PubMed Central

    Saunders, CJ

    2013-01-01

    Polymodal neurons of the trigeminal nerve innervate the nasal cavity, nasopharynx, oral cavity and cornea. Trigeminal nociceptive fibers express a diverse collection of receptors and are stimulated by a wide variety of chemicals. However, the mechanism of stimulation is known only for relatively few of these compounds. Capsaicin, for example, activates transient receptor potential vanilloid 1 (TRPV1) channels. In the present study, wildtype (C57Bl/6J) and TRPV1 knockout mice were tested in three behavioral assays for irritation to determine if TRPV1 is necessary to detect trigeminal irritants in addition to capsaicin. In one assay mice were presented with a chemical via a cotton swab and their response scored on a 5 level scale. In another assay, a modified two bottle preference test, which avoids the confound of mixing irritants with the animal’s drinking water, was used to assess aversion. In the final assay, an air dilution olfactometer was used to administer volatile compounds to mice restrained in a double-chambered plethysmograph where respiratory reflexes were monitored. TRPV1 knockouts showed deficiencies in the detection of benzaldehyde, cyclohexanone and eugenol in at least one assay. However, cyclohexanone was the only substance tested that appears to act solely through TRPV1. PMID:24358880

  6. Mechanisms and clinical uses of capsaicin.

    PubMed

    Sharma, Surinder Kumar; Vij, Amarjit Singh; Sharma, Mohit

    2013-11-15

    Capsaicin is the active ingredient of chili peppers and gives them the characteristic pungent flavor. Understanding the actions of capsaicin led to the discovery of its receptor, transient receptor potential vanilloid subfamily member 1 (TRPV1). This receptor is found on key sensory afferents, and so the use of capsaicin to selectively activate pain afferents has been studied in animal and human models for various indications. Capsaicin is unique among naturally occurring irritant compounds because the initial neuronal excitation evoked by it is followed by a long-lasting refractory period, during which the previously excited neurons are no longer responsive to a broad range of stimuli. This process known as defunctionalisation has been exploited for therapeutic use of capsaicin in various painful conditions. We reviewed different studies on mechanisms of action of capsaicin and its utility in different clinical conditions. A beneficial role of capsaicin has been reported in obesity, cardiovascular and gastrointestinal conditions, various cancers, neurogenic bladder, and dermatologic conditions. Various theories have been put forth to explain these effects. Interestingly many of these pharmacological actions are TRPV1 independent. This review is aimed at providing an overview of these mechanisms and to also present literature which contradicts the proposed beneficial effects of capsaicin. Most of the literature comes from animal studies and since many of these mechanisms are poorly understood, more investigation is required in human subjects. PMID:24211679

  7. An alternative splicing product of the murine trpv1 gene dominant negatively modulates the activity of TRPV1 channels.

    PubMed

    Wang, Chunbo; Hu, Hong-Zhen; Colton, Craig K; Wood, Jackie D; Zhu, Michael X

    2004-09-01

    Transient receptor potential vanilloid 1 (TRPV1), or vanilloid receptor 1, is the founding member of the vanilloid type of TRP superfamily of nonselective cation channels. TRPV1 is activated by noxious heat, acid, and alkaloid irritants as well as several endogenous ligands and is sensitized by inflammatory factors, thereby serving important functions in detecting noxious stimuli in the sensory system and pathological states in different parts of the body. Whereas numerous studies have been carried out using the rat and human TRPV1 cDNA, the mouse TRPV1 cDNA has not been characterized. Here, we report molecular cloning of two TRPV1 cDNA variants from dorsal root ganglia of C57BL/6 mice. The deduced proteins are designated TRPV1alpha and TRPV1beta and contain 839 and 829 amino acids, respectively. TRPV1beta arises from an alternative intron recognition signal within exon 7 of the trpv1 gene. We found a predominant expression of TRPV1alpha in many tissues and significant expression of TRPV1beta in dorsal root ganglia, skin, stomach, and tongue. When expressed in HEK 293 cells or Xenopus oocytes, TRPV1alpha formed a Ca(2+)-permeable channel activated by ligands known to stimulate TRPV1. TRPV1beta was not functional by itself but its co-expression inhibited the function of TRPV1alpha. Furthermore, although both isoforms were synthesized at a similar rate, less TRPV1beta than TRPV1alpha protein was found in cells and on the cell surface, indicating that the beta isoform is highly unstable. Our data suggest that TRPV1beta is a naturally occurring dominant-negative regulator of the responses of sensory neurons to noxious stimuli. PMID:15234965

  8. Discovery of SB-705498: a potent, selective and orally bioavailable TRPV1 antagonist suitable for clinical development.

    PubMed

    Rami, Harshad K; Thompson, Mervyn; Stemp, Geoffrey; Fell, Steve; Jerman, Jeffrey C; Stevens, Alexander J; Smart, Darren; Sargent, Becky; Sanderson, Dominic; Randall, Andrew D; Gunthorpe, Martin J; Davis, John B

    2006-06-15

    Small molecule antagonists of the vanilloid receptor TRPV1 (also known as VR1) are disclosed. Pyrrolidinyl ureas such as 8 and 15 (SB-705498) emerged as lead compounds following optimisation of the previously described urea SB-452533. Pharmacological studies using electrophysiological and FLIPR-Ca2+-based assays showed that compounds such as 8 and 15 were potent antagonists versus the multiple chemical and physical modes of TRPV1 activation (namely capsaicin, acid and noxious heat). Furthermore, 15 possessed suitable developability properties to enable progression of this compound into in vivo studies and subsequently clinical development. PMID:16580202

  9. TRPV1 channels are functionally coupled with BK(mSlo1) channels in rat dorsal root ganglion (DRG) neurons.

    PubMed

    Wu, Ying; Liu, Yongfeng; Hou, Panpan; Yan, Zonghe; Kong, Wenjuan; Liu, Beiying; Li, Xia; Yao, Jing; Zhang, Yuexuan; Qin, Feng; Ding, Jiuping

    2013-01-01

    The transient receptor potential vanilloid receptor 1 (TRPV1) channel is a nonselective cation channel activated by a variety of exogenous and endogenous physical and chemical stimuli, such as temperature (≥42 °C), capsaicin, a pungent compound in hot chili peppers, and allyl isothiocyanate. Large-conductance calcium- and voltage-activated potassium (BK) channels regulate the electric activities and neurotransmitter releases in excitable cells, responding to changes in membrane potentials and elevation of cytosolic calcium ions (Ca(2+)). However, it is unknown whether the TRPV1 channels are coupled with the BK channels. Using patch-clamp recording combined with an infrared laser device, we found that BK channels could be activated at 0 mV by a Ca(2+) influx through TRPV1 channels not the intracellular calcium stores in submilliseconds. The local calcium concentration around BK is estimated over 10 μM. The crosstalk could be affected by 10 mM BAPTA, whereas 5 mM EGTA was ineffectual. Fluorescence and co-immunoprecipitation experiments also showed that BK and TRPV1 were able to form a TRPV1-BK complex. Furthermore, we demonstrated that the TRPV1-BK coupling also occurs in dosal root ganglion (DRG) cells, which plays a critical physiological role in regulating the "pain" signal transduction pathway in the peripheral nervous system. PMID:24147119

  10. Four Possible Itching Pathways Related to the TRPV1 Channel, Histamine, PAR-2 and Serotonin

    PubMed Central

    NAKAGAWA, Hiroshi; HIURA, Akio

    2013-01-01

    The following four possible pathways for itching sensation have been suggested by recent reports. 1) Histaminergic TRPV1-positive pathway: Although histamine-positive nerve fibers cannot strictly be classified as “itch specific” due to their excitation also by pure algogens (making them itch-selective), the existence of a subpopulation of nociceptors responsible for itching is strongly suggested. Moreover, the TRPV1-expressing neurons have been suggested to be the main sensors and mediators of itching. 2) Histaminergic TRPV1-negative pathway: The scratching behavior caused by itching was not different between capsaicin-pre-treated and vehicle-treated (control) mast cell-rich NC mice. This result suggests the existence of a capsaicin-insensitive (TRPV1-negative) histaminergic pathway. 3) Non-histaminergic PAR-2 pathway: Protease-activated receptor 2 (PAR-2) has been shown to play a role in the itching of atopic dermatitis (AD). The itch evoked by cowhage (a non-histaminergic pruritogen that activates PAR-2) is very similar in characteristics to the itch evoked by conditions such as AD. 4) Non-histaminergic serotonin (5-HT) pathway: 5-HT alone applied to the human skin evokes an itching sensation and has been suggested to be involved in the itching associated with pruritic diseases, such as polycythemia vera and cholestasis. PMID:24043991

  11. Palmitoylethanolamide normalizes intestinal motility in a model of post-inflammatory accelerated transit: involvement of CB1 receptors and TRPV1 channels

    PubMed Central

    Capasso, Raffaele; Orlando, Pierangelo; Pagano, Ester; Aveta, Teresa; Buono, Lorena; Borrelli, Francesca; Di Marzo, Vincenzo; Izzo, Angelo A

    2014-01-01

    Background and Purpose Palmitoylethanolamide (PEA), a naturally occurring acylethanolamide chemically related to the endocannabinoid anandamide, interacts with targets that have been identified in peripheral nerves controlling gastrointestinal motility, such as cannabinoid CB1 and CB2 receptors, TRPV1 channels and PPARα. Here, we investigated the effect of PEA in a mouse model of functional accelerated transit which persists after the resolution of colonic inflammation (post-inflammatory irritable bowel syndrome). Experimental Approach Intestinal inflammation was induced by intracolonic administration of oil of mustard (OM). Mice were tested for motility and biochemical and molecular biology changes 4 weeks later. PEA, oleoylethanolamide and endocannabinoid levels were measured by liquid chromatography-mass spectrometry and receptor and enzyme mRNA expression by qRT-PCR. Key Results OM induced transient colitis and a functional post-inflammatory increase in upper gastrointestinal transit, associated with increased intestinal anandamide (but not 2-arachidonoylglycerol, PEA or oleoylethanolamide) levels and down-regulation of mRNA for TRPV1 channels. Exogenous PEA inhibited the OM-induced increase in transit and tended to increase anandamide levels. Palmitic acid had a weaker effect on transit. Inhibition of transit by PEA was blocked by rimonabant (CB1 receptor antagonist), further increased by 5′-iodoresiniferatoxin (TRPV1 antagonist) and not significantly modified by the PPARα antagonist GW6471. Conclusions and Implications Intestinal endocannabinoids and TRPV1 channel were dysregulated in a functional model of accelerated transit exhibiting aspects of post-inflammatory irritable bowel syndrome. PEA counteracted the accelerated transit, the effect being mediated by CB1 receptors (possibly via increased anandamide levels) and modulated by TRPV1 channels. PMID:24818658

  12. The capsaicin receptor participates in artificial sweetener aversion.

    PubMed

    Riera, Céline E; Vogel, Horst; Simon, Sidney A; Damak, Sami; le Coutre, Johannes

    2008-11-28

    Artificial sweeteners such as saccharin, aspartame, acesulfame-K, and cyclamate produce at high concentrations an unpleasant after-taste that is generally attributed to bitter and metallic taste sensations. To identify receptors involved with the complex perception of the above compounds, preference tests were performed in wild-type mice and mice lacking the TRPV1 channel or the T1R3 receptor, the latter being necessary for the perception of sweet taste. The sweeteners, including cyclamate, displayed a biphasic response profile, with the T1R3 mediated component implicated in preference. At high concentrations imparting off-taste, omission of TRPV1 reduced aversion. In a heterologous expression system the Y511A point mutation in the vanilloid pocket of TRPV1 did not affect saccharin and aspartame responses but abolished cyclamate and acesulfame-K activities. The results rationalize artificial sweetener tastes and off-tastes by showing that at low concentrations, these molecules stimulate the gustatory system through the hedonically positive T1R3 pathway, and at higher concentrations, their aversion is partly mediated by TRPV1. PMID:18804451

  13. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    PubMed Central

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx–TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

  14. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1.

    PubMed

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

  15. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    NASA Astrophysics Data System (ADS)

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, Kewei; Lai, Ren

    2015-09-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery.

  16. 2-(3-Fluoro-4-methylsulfonylaminophenyl) Propanamides as Potent Transient Receptor Potential Vanilloid 1 (TRPV1) Antagonists: Structure Activity Relationships of 2-Amino Derivatives in the N-(6-trifluoromethyl-pyridin-3-ylmethyl) C-region

    PubMed Central

    Kim, Myeong Seop; Ryu, HyungChul; Kang, Dong Wook; Cho, Seong-Hee; Seo, Sejin; Park, Young Soo; Kim, Mi-Yeon; Kwak, Eun Joo; Kim, Yong Soo; Bhondwe, Rahul S.; Kim, Ho Shin; Park, Seul-gi; Son, Karam; Choi, Sun; DeAndrea-Lazarus, Ian; Pearce, Larry V.; Blumberg, Peter M.; Frank, Robert; Bahrenberg, Gregor; Stockhausen, Hannelore; Kögel, Babette Y.; Schiene, Klaus; Christoph, Thomas; Lee, Jeewoo

    2012-01-01

    A series of N-(2-amino-6-trifluoromethyl-pyridin-3-ylmethyl) 2-(3-fluoro-4-methylsulfonylaminophenyl) propanamides were designed combining previously identified pharmacophoric elements and evaluated as hTRPV1 antagonists. The SAR analysis indicated that specific hydrophobic interactions of the 2-amino substituents in the C-region of the ligand were critical for high hTRPV1binding potency. In particular, compound 49S was an excellent TRPV1 antagonist (Ki(CAP) = 0.2 nM; IC50(pH) = 6.3 nM) and was thus ca. 100- and 20-fold more potent, respectively, than the parent compounds 2 and 3 for capsaicin antagonism. Furthermore, it demonstrated strong analgesic activity in the rat neuropathic model superior to 2 with almost no side effects. Compound 49S antagonized capsaicin induced hypothermia in mice, but showed TRPV1-related hyperthermia. The basis for the high potency of 49S compared to 2 is suggested by docking analysis with our hTRPV1 homology model in which the 4-methylpiperidinyl group in the C-region of 49S made additional hydrophobic interactions with the hydrophobic region. PMID:22957803

  17. Effect of capsaicin on thermoregulation: an update with new aspects

    PubMed Central

    Szolcsányi, János

    2015-01-01

    Capsaicin, a selective activator of the chemo- and heat-sensitive transient receptor potential (TRP) V1 cation channel, has characteristic feature of causing long-term functional and structural impairment of neural elements supplied by TRPV1/capsaicin receptor. In mammals, systemic application of capsaicin induces complex heat-loss response characteristic for each species and avoidance of warm environment. Capsaicin activates cutaneous warm receptors and polymodal nociceptors but has no effect on cold receptors or mechanoreceptors. In this review, thermoregulatory features of capsaicin-pretreated rodents and TRPV1-mediated neural elements with innocuous heat sensitivity are summarized. Recent data support a novel hypothesis for the role of visceral warmth sensors in monitoring core body temperature. Furthermore, strong evidence suggests that central presynaptic nerve terminals of TRPV1-expressing cutaneous, thoracic and abdominal visceral receptors are activated by innocuous warmth stimuli and capsaicin. These responses are absent in TRPV1 knockout mice. Thermoregulatory disturbance induced by systemic capsaicin pretreatment lasts for months and is characterized by a normal body temperature at cool environment up to a total dose of 150 mg/kg s.c. Upward differential shift of set points for activation vasodilation, other heat-loss effectors and thermopreference develops. Avoidance of warm ambient temperature (35°C, 40°C) is severely impaired but thermopreference at cool ambient temperatures (Tas) are not altered. TRPV1 knockout or knockdown and genetically altered TRPV1, TRPV2 and TRPM8 knockout mice have normal core temperature in thermoneutral or cool environments, but the combined mutant mice have impaired regulation in warm or cold (4°C) environments. Several lines of evidence support that in the preoptic area warmth sensitive neurons are activated and desensitized by capsaicin, but morphological evidence for it is controversial. It is suggested that these

  18. Effect of capsaicin on thermoregulation: an update with new aspects.

    PubMed

    Szolcsányi, János

    2015-01-01

    Capsaicin, a selective activator of the chemo- and heat-sensitive transient receptor potential (TRP) V1 cation channel, has characteristic feature of causing long-term functional and structural impairment of neural elements supplied by TRPV1/capsaicin receptor. In mammals, systemic application of capsaicin induces complex heat-loss response characteristic for each species and avoidance of warm environment. Capsaicin activates cutaneous warm receptors and polymodal nociceptors but has no effect on cold receptors or mechanoreceptors. In this review, thermoregulatory features of capsaicin-pretreated rodents and TRPV1-mediated neural elements with innocuous heat sensitivity are summarized. Recent data support a novel hypothesis for the role of visceral warmth sensors in monitoring core body temperature. Furthermore, strong evidence suggests that central presynaptic nerve terminals of TRPV1-expressing cutaneous, thoracic and abdominal visceral receptors are activated by innocuous warmth stimuli and capsaicin. These responses are absent in TRPV1 knockout mice. Thermoregulatory disturbance induced by systemic capsaicin pretreatment lasts for months and is characterized by a normal body temperature at cool environment up to a total dose of 150 mg/kg s.c. Upward differential shift of set points for activation vasodilation, other heat-loss effectors and thermopreference develops. Avoidance of warm ambient temperature (35°C, 40°C) is severely impaired but thermopreference at cool ambient temperatures (Tas) are not altered. TRPV1 knockout or knockdown and genetically altered TRPV1, TRPV2 and TRPM8 knockout mice have normal core temperature in thermoneutral or cool environments, but the combined mutant mice have impaired regulation in warm or cold (4°C) environments. Several lines of evidence support that in the preoptic area warmth sensitive neurons are activated and desensitized by capsaicin, but morphological evidence for it is controversial. It is suggested that these

  19. Hyaluronan modulates TRPV1 channel opening, reducing peripheral nociceptor activity and pain

    PubMed Central

    Caires, Rebeca; Luis, Enoch; Taberner, Francisco J.; Fernandez-Ballester, Gregorio; Ferrer-Montiel, Antonio; Balazs, Endre A.; Gomis, Ana; Belmonte, Carlos; de la Peña, Elvira

    2015-01-01

    Hyaluronan (HA) is present in the extracellular matrix of all body tissues, including synovial fluid in joints, in which it behaves as a filter that buffers transmission of mechanical forces to nociceptor nerve endings thereby reducing pain. Using recombinant systems, mouse-cultured dorsal root ganglia (DRG) neurons and in vivo experiments, we found that HA also modulates polymodal transient receptor potential vanilloid subtype 1 (TRPV1) channels. HA diminishes heat, pH and capsaicin (CAP) responses, thus reducing the opening probability of the channel by stabilizing its closed state. Accordingly, in DRG neurons, HA decreases TRPV1-mediated impulse firing and channel sensitization by bradykinin. Moreover, subcutaneous HA injection in mice reduces heat and capsaicin nocifensive responses, whereas the intra-articular injection of HA in rats decreases capsaicin joint nociceptor fibres discharge. Collectively, these results indicate that extracellular HA reduces the excitability of the ubiquitous TRPV1 channel, thereby lowering impulse activity in the peripheral nociceptor endings underlying pain. PMID:26311398

  20. Activation of transient receptor potential A1 by a non-pungent capsaicin-like compound, capsiate

    PubMed Central

    Shintaku, Kenji; Uchida, Kunitoshi; Suzuki, Yoshiro; Zhou, Yiming; Fushiki, Tohru; Watanabe, Tatsuo; Yazawa, Susumu; Tominaga, Makoto

    2012-01-01

    BACKGROUND AND PURPOSE Capsiate is produced by ‘CH-19 Sweet’ (Capsicum annuun L.), a non-pungent cultivar of red pepper. Like capsaicin, capsiate is thought to enhance energy metabolism by activating the sympathetic nervous system and suppressing inflammation, but the underlying mechanisms for this are uncertain. We previously reported that capsiate could activate transient receptor potential vanilloid 1 (TRPV1), a capsaicin receptor. The purpose of the present study is to investigate whether capsinoids activate other TRP channels. EXPERIMENTAL APPROACH Using Ca2+ imaging and whole-cell patch-clamp methods, we analysed the response of TRP channels to three kinds of capsinoids, capsiate, dihydrocapsiate and nordihydrocapsiate, in HEK293T cells expressing TRP channels or in primary cultures of mouse dorsal root ganglion neurons. KEY RESULTS We found that in both cell types TRP ankyrin 1 (TRPA1) had a slightly weaker response to capsinoids compared with TRPV1, with the capsiate EC50 for TRPA1 activation being more than that for TRPV1 activation, and that the capsinoid-evoked action was blocked by a specific TRPA1 antagonist. TRPA1 was activated by capsinoids, but not by their degradation products. Amino acids known to participate in TRPA1 activation following cysteine covalent modification or zinc treatment were not involved in the activation of TRPA1 by capsinoid. CONCLUSIONS AND IMPLICATIONS Taken together, these results indicate that capsinoids activate TRPA1 by an as yet unknown mechanism, and TRPA1 could be involved in physiological phenomena associated with capsinoid treatment. PMID:21883144

  1. Photoswitchable fatty acids enable optical control of TRPV1

    PubMed Central

    Frank, James Allen; Moroni, Mirko; Moshourab, Rabih; Sumser, Martin; Lewin, Gary R.; Trauner, Dirk

    2015-01-01

    Fatty acids (FAs) are not only essential components of cellular energy storage and structure, but play crucial roles in signalling. Here we present a toolkit of photoswitchable FA analogues (FAAzos) that incorporate an azobenzene photoswitch along the FA chain. By modifying the FAAzos to resemble capsaicin, we prepare a series of photolipids targeting the Vanilloid Receptor 1 (TRPV1), a non-selective cation channel known for its role in nociception. Several azo-capsaicin derivatives (AzCAs) emerge as photoswitchable agonists of TRPV1 that are relatively inactive in the dark and become active on irradiation with ultraviolet-A light. This effect can be rapidly reversed by irradiation with blue light and permits the robust optical control of dorsal root ganglion neurons and C-fibre nociceptors with precision timing and kinetics not available with any other technique. More generally, we expect that photolipids will find many applications in controlling biological pathways that rely on protein–lipid interactions. PMID:25997690

  2. Photoswitchable fatty acids enable optical control of TRPV1.

    PubMed

    Frank, James Allen; Moroni, Mirko; Moshourab, Rabih; Sumser, Martin; Lewin, Gary R; Trauner, Dirk

    2015-01-01

    Fatty acids (FAs) are not only essential components of cellular energy storage and structure, but play crucial roles in signalling. Here we present a toolkit of photoswitchable FA analogues (FAAzos) that incorporate an azobenzene photoswitch along the FA chain. By modifying the FAAzos to resemble capsaicin, we prepare a series of photolipids targeting the Vanilloid Receptor 1 (TRPV1), a non-selective cation channel known for its role in nociception. Several azo-capsaicin derivatives (AzCAs) emerge as photoswitchable agonists of TRPV1 that are relatively inactive in the dark and become active on irradiation with ultraviolet-A light. This effect can be rapidly reversed by irradiation with blue light and permits the robust optical control of dorsal root ganglion neurons and C-fibre nociceptors with precision timing and kinetics not available with any other technique. More generally, we expect that photolipids will find many applications in controlling biological pathways that rely on protein-lipid interactions. PMID:25997690

  3. Capsaicin may have important potential for promoting vascular and metabolic health

    PubMed Central

    McCarty, Mark F; DiNicolantonio, James J; O'Keefe, James H

    2015-01-01

    Capsaicin, the phytochemical responsible for the spiciness of peppers, has the potential to modulate metabolism via activation of transient receptor potential vanilloid 1 (TRPV1) receptors, which are found not only on nociceptive sensory neurons, but also in a range of other tissues. TRPV1 activation induces calcium influx, and in certain tissues this is associated with increased activation or expression of key proteins such as endothelial nitric oxide synthase (eNOS), uncoupling protein 2 (UCP2), KLF2, PPARdelta, PPARgamma, and LXRα. The calcium influx triggered by TRPV1 activation in endothelial cells mimics the impact of shear stress in this regard, activating and increasing the expression of eNOS—but also increasing expression of cox-2, thrombomodulin, and nrf2-responsive antioxidant enzymes, while decreasing expression of proinflammatory proteins. Hence, dietary capsaicin has favourably impacted endothelium-dependent vasodilation in rodents. TRPV1-mediated induction of LXRα in foam cells promotes cholesterol export, antagonising plaque formation. Capsaicin-mediated activation of TRPV1-expressing neurons in the gastrointestinal tract promotes sympathetically mediated stimulation of brown fat, raising metabolic rate. The increased expression of UCP2 induced by TRPV1 activation exerts a protective antioxidant effect on the liver in non-alcoholic fatty liver disease, and on vascular endothelium in the context of hyperglycaemia. In rodent studies, capsaicin-rich diets have shown favourable effects on atherosclerosis, metabolic syndrome, diabetes, obesity, non-alcoholic fatty liver, cardiac hypertrophy, hypertension and stroke risk. Clinically, ingestion of capsaicin—or its less stable non-pungent analogue capsiate—has been shown to boost metabolic rate modestly. Topical application of capsaicin via patch was found to increase exercise time to ischaemic threshold in patients with angina. Further clinical studies with capsaicin administered in food, capsules

  4. Molecular Determinants of Phosphatidylinositol 4,5-Bisphosphate (PI(4,5)P2) Binding to Transient Receptor Potential V1 (TRPV1) Channels*

    PubMed Central

    Poblete, Horacio; Oyarzún, Ingrid; Olivero, Pablo; Comer, Jeffrey; Zuñiga, Matías; Sepulveda, Romina V.; Báez-Nieto, David; González Leon, Carlos; González-Nilo, Fernando; Latorre, Ramón

    2015-01-01

    Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) has been recognized as an important activator of certain transient receptor potential (TRP) channels. More specifically, TRPV1 is a pain receptor activated by a wide range of stimuli. However, whether or not PI(4,5)P2 is a TRPV1 agonist remains open to debate. Utilizing a combined approach of mutagenesis and molecular modeling, we identified a PI(4,5)P2 binding site located between the TRP box and the S4-S5 linker. At this site, PI(4,5)P2 interacts with the amino acid residues Arg-575 and Arg-579 in the S4-S5 linker and with Lys-694 in the TRP box. We confirmed that PI(4,5)P2 behaves as a channel agonist and found that Arg-575, Arg-579, and Lys-694 mutations to alanine reduce PI(4,5)P2 binding affinity. Additionally, in silico mutations R575A, R579A, and K694A showed that the reduction in binding affinity results from the delocalization of PI(4,5)P2 in the binding pocket. Molecular dynamics simulations indicate that PI(4,5)P2 binding induces conformational rearrangements of the structure formed by S6 and the TRP domain, which cause an opening of the lower TRPV1 channel gate. PMID:25425643

  5. Inhibition of TRPV1 for the treatment of sensitive skin.

    PubMed

    Kueper, Thomas; Krohn, Michael; Haustedt, Lars Ole; Hatt, Hanns; Schmaus, Gerhard; Vielhaber, Gabriele

    2010-11-01

    During the past years, the topic sensitive skin became one of the most important fields in dermatology. The tremendous interest is based on several studies showing that about 50% of the population declares to have sensitive skin. The human thermoreceptor hTRPV1 was previously identified to contribute to this skin condition while facilitating neurogenic inflammation leading to hyperalgesia. Furthermore, skin sensitivity towards capsaicin, a natural activator of TRPV1, was shown to correlate with sensitive skin. In a screening campaign based on recombinant HEK293-cells stably transfected with hTRPV1, the selective antagonist trans-4-tert-butylcyclohexanol was identified. This antagonist is able to inhibit capsaicin-induced hTRPV1 activation with an IC(50) value of 34 ± 5 μm tested in HEK293-cells as well as in electrophysiological recordings performed in oocytes expressing hTRPV1. Strikingly, in a clinical study with 30 women using topical treatment with o/w emulsions containing 31.6 ppm capsaicin, we were able to show that 0.4% of this inhibitor significantly reduces capsaicin-induced burning (P < 0.0001) in vivo. Thus trans-4-tert-butylcyclohexanol has the potential as a novel bioactive for the treatment of sensitive skin. PMID:20626462

  6. Differential Regulation of Proton-Sensitive Ion Channels by Phospholipids: A Comparative Study between ASICs and TRPV1

    PubMed Central

    Kweon, Hae-Jin; Yu, Soo-Young; Kim, Dong-Il; Suh, Byung-Chang

    2015-01-01

    Protons are released in pain-generating pathological conditions such as inflammation, ischemic stroke, infection, and cancer. During normal synaptic activities, protons are thought to play a role in neurotransmission processes. Acid-sensing ion channels (ASICs) are typical proton sensors in the central nervous system (CNS) and the peripheral nervous system (PNS). In addition to ASICs, capsaicin- and heat-activated transient receptor potential vanilloid 1 (TRPV1) channels can also mediate proton-mediated pain signaling. In spite of their importance in perception of pH fluctuations, the regulatory mechanisms of these proton-sensitive ion channels still need to be further investigated. Here, we compared regulation of ASICs and TRPV1 by membrane phosphoinositides, which are general cofactors of many receptors and ion channels. We observed that ASICs do not require membrane phosphatidylinositol 4-phosphate (PI(4)P) or phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) for their function. However, TRPV1 currents were inhibited by simultaneous breakdown of PI(4)P and PI(4,5)P2. By using a novel chimeric protein, CF-PTEN, that can specifically dephosphorylate at the D3 position of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3), we also observed that neither ASICs nor TRPV1 activities were altered by depletion of PI(3,4,5)P3 in intact cells. Finally, we compared the effects of arachidonic acid (AA) on two proton-sensitive ion channels. We observed that AA potentiates the currents of both ASICs and TRPV1, but that they have different recovery aspects. In conclusion, ASICs and TRPV1 have different sensitivities toward membrane phospholipids, such as PI(4)P, PI(4,5)P2, and AA, although they have common roles as proton sensors. Further investigation about the complementary roles and respective contributions of ASICs and TRPV1 in proton-mediated signaling is necessary. PMID:25781982

  7. Some like it hot: The emerging role of spicy food (capsaicin) in autoimmune diseases.

    PubMed

    Deng, Yaxiong; Huang, Xin; Wu, Haijing; Zhao, Ming; Lu, Qianjin; Israeli, Eitan; Dahan, Shani; Blank, Miri; Shoenfeld, Yehuda

    2016-05-01

    Autoimmune diseases refer to a spectrum of diseases characterized by an active immune response against the host, which frequently involves increased autoantibody production. The pathogenesis of autoimmune diseases is multifactorial and the exploitation of novel effective treatment is urgent. Capsaicin is a nutritional factor, the active component of chili peppers, which is responsible for the pungent component of chili pepper. As a stimuli, capsaicin selectively activate transient receptor potential vanilloid subfamily 1(TRPV1) and exert various biological effects. This review discusses the effect of capsaicin through its receptor on the development and modulation of autoimmune diseases, which may shed light upon potential therapies in capsaicin-targeted approaches. PMID:26812350

  8. Identification and biological characterization of 6-aryl-7-isopropylquinazolinones as novel TRPV1 antagonists that are effective in models of chronic pain.

    PubMed

    Culshaw, Andrew J; Bevan, Stuart; Christiansen, Martin; Copp, Prafula; Davis, Andrew; Davis, Clare; Dyson, Alex; Dziadulewicz, Edward K; Edwards, Lee; Eggelte, Hendrikus; Fox, Alyson; Gentry, Clive; Groarke, Alex; Hallett, Allan; Hart, Terance W; Hughes, Glyn A; Knights, Sally; Kotsonis, Peter; Lee, Wai; Lyothier, Isabelle; McBryde, Andrew; McIntyre, Peter; Paloumbis, George; Panesar, Moh; Patel, Sadhana; Seiler, Max-Peter; Yaqoob, Mohammed; Zimmermann, Kaspar

    2006-01-26

    Vanilloid receptor 1 (VR1, TRPV1) is a cation-selective ion channel that is expressed on primary afferent neurons and is upregulated following inflammation and nerve damage. Blockers of this channel may have utility in the treatment of chronic nociceptive and neuropathic pain. Here, we describe the optimization from a high throughput screening hit, of a series of 6-aryl-7-isopropylquinazolinones that are TRPV1 antagonists in vitro. We also demonstrate that one compound is active in vivo against capsaicin-induced hyperalgesia and in models of neuropathic and nociceptive pain in the rat. PMID:16420034

  9. Activation of the TRPV1 Cation Channel Contributes to Stress-Induced Astrocyte Migration

    PubMed Central

    Ho, Karen W.; Lambert, Wendi S.; Calkins, David J.

    2014-01-01

    Astrocytes provide metabolic, structural and synaptic support to neurons in normal physiology and also contribute widely to pathogenic processes in response to stress or injury. Reactive astrocytes can undergo cytoskeletal reorganization and increase migration through changes in intracellular Ca2+ mediated by a variety of potential modulators. Here we tested whether migration of isolated retinal astrocytes following mechanical injury (scratch wound) involves the transient receptor potential vanilloid-1 channel (TRPV1), which contributes to Ca2+-mediated cytoskeletal rearrangement and migration in other systems. Application of the TRPV1-specific antagonists, capsazepine (CPZ) or 5’-iodoresiniferatoxin (IRTX), slowed migration by as much as 44%, depending on concentration. In contrast, treatment with the TRPV1-specific agonists, capsaicin (CAP) or resiniferatoxin (RTX) produced only a slight acceleration over a range of concentrations. Chelation of extracellular Ca2+ with EGTA (1 mM) slowed astrocyte migration by 35%. Ratiometric imaging indicated that scratch wound induced a sharp 20% rise in astrocyte Ca2+ that dissipated with distance from the wound. Treatment with IRTX both slowed and dramatically reduced the scratch-induced Ca2+ increase. Both CPZ and IRTX influenced astrocyte cytoskeletal organization, especially near the wound edge. Taken together, our results indicate that astrocyte mobilization in response to mechanical stress involves influx of extracellular Ca2+ and cytoskeletal changes in part mediated by TRPV1 activation. PMID:24838827

  10. Involvement of capsaicin-sensitive afferent nerves in the proteinase-activated receptor 2-mediated vasodilatation in the rat dura mater.

    PubMed

    Dux, M; Rosta, J; Sántha, P; Jancsó, G

    2009-07-01

    Neurogenic inflammation of the dura mater encephali has been suggested to contribute to the mechanisms of meningeal nociception and blood flow regulation. Recent findings demonstrated that the rat dura mater is innervated by trigeminal capsaicin-sensitive peptidergic nociceptive afferent nerves which mediate meningeal vascular responses through activation of the transient receptor potential vanilloid type 1 (TRPV1) receptor. The present work explored the functional significance of the capsaicin-sensitive subpopulation of dural afferent nerves via their contribution to the meningeal vascular responses evoked through activation of the proteinase-activated receptor 2 (PAR-2). The vascular responses of the dura mater were studied by laser Doppler flowmetry in a rat open cranial window preparation. Topical applications of trypsin, a PAR-2-activator, or Ser-Leu-Ile-Gly-Arg-Leu-amide (SLIGRL-NH(2)), a selective PAR-2 agonist peptide, resulted in dose-dependent increases in meningeal blood flow. The SLIGRL-NH(2)-induced vasodilatation was significantly reduced following capsaicin-sensitive afferent nerve defunctionalization by prior systemic capsaicin treatment and by pretreatment of the dura mater with the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP(8-37). Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME) an unspecific inhibitor of nitric oxide (NO) production, but not 1-(2-trifluoromethylphenyl) imidazole (TRIM), a neuronal NO synthase inhibitor, also inhibited the vasodilator response to SLIGRL-NH(2). The vasodilator responses elicited by very low concentrations of capsaicin (10 nM) were significantly enhanced by prior application of SLIGRL-NH(2). The present findings demonstrate that activation of the PAR-2 localized on capsaicin-sensitive trigeminal nociceptive afferent nerves induces vasodilatation in the dural vascular bed by mechanisms involving NO and CGRP release. The results indicate that the PAR-2-mediated activation and

  11. Sensory attributes of complex tasting divalent salts are mediated by TRPM5 and TRPV1 channels.

    PubMed

    Riera, Céline E; Vogel, Horst; Simon, Sidney A; Damak, Sami; le Coutre, Johannes

    2009-02-25

    Complex tasting divalent salts (CTDS) are present in our daily diet, contributing to multiple poorly understood taste sensations. CTDS evoking metallic, bitter, salty, and astringent sensations include the divalent salts of iron, zinc, copper, and magnesium. To identify pathways involved with the complex perception of the above salts, taste preference tests (two bottles, brief access) were performed in wild-type (WT) mice and in mice lacking (1) the T1R3 receptor, (2) TRPV1, the capsaicin receptor, or (3) the TRPM5 channel, the latter being necessary for the perception of sweet, bitter, and umami tasting stimuli. At low concentrations, FeSO(4) and ZnSO(4) were perceived as pleasant stimuli by WT mice, and this effect was fully reversed in TRPM5 knock-out mice. In contrast, MgSO(4) and CuSO(4) were aversive to WT mice, but for MgSO(4) the aversion was abolished in TRPM5 knock-out animals, and for CuSO(4), aversion decreased in both TRPV1- and TRPM5-deficient animals. Behavioral tests revealed that the T1R3 subunit of the sweet and umami receptors is implicated in the hedonically positive perception of FeSO(4) and ZnSO(4). For high concentrations of CTDS, the omission of TRPV1 reduced aversion. Imaging studies on heterologously expressed TRPM5 and TRPV1 channels are consistent with the behavioral experiments. Together, these results rationalize the complexity of metallic taste by showing that at low concentrations, compounds such as FeSO(4) and ZnSO(4) stimulate the gustatory system through the hedonically positive T1R3-TRPM5 pathway, and at higher concentrations, their aversion is mediated, in part, by the activation of TRPV1. PMID:19244541

  12. Abundant expression and functional participation of TRPV1 at Zusanli acupoint (ST36) in mice: mechanosensitive TRPV1 as an “acupuncture-responding channel”

    PubMed Central

    2014-01-01

    Background Acupuncture is a therapy that involves applying mechanical stimulation to acupoints using needles. Although acupuncture is believed to trigger neural regulation by opioids or adenosine, still little is known about how physical stimulation is turned into neurological signaling. The transient receptor potential vanilloid receptors 1 and 4 (TRPV1 and TRPV4) and the acid-sensing ion channel 3 (ASIC3) are regarded as mechanosensitive channels. This study aimed to clarify their role at the Zusanli acupoint (ST36) and propose possible sensing pathways linking channel activation to neurological signaling. Methods First, tissues from different anatomical layers of ST36 and the sham point were sampled, and channel expressions between the two points were compared using western blotting. Second, immunofluorescence was performed at ST36 to reveal distribution pattern of the channels. Third, agonist of the channels were injected into ST36 and tested in a mouse inflammatory pain model to seek if agonist injection could replicate acupuncture-like analgesic effect. Last, the components of proposed downstream sensing pathway were tested with western blotting to determine if they were expressed in tissues with positive mechanosensitive channel expression. Results The results from western blotting demonstrated an abundance of TRPV1, TRPV4, and ASIC3 in anatomical layers of ST36. Furthermore, immunofluorescence showed these channels were expressed in both neural and non-neural cells at ST36. However, only capsaicin, a TRPV1 agonist, replicated the analgesic effect of acupuncture when injected into ST36. Components of calcium wave propagation (CWP, the proposed downstream sensing pathway) were also expressed in tissues with abundant TRPV1 expression, the muscle and epimysium layers. Conclusions The results demonstrated mechanosensitive channel TRPV1 is highly expressed at ST36 and possibly participated in acupuncture related analgesia. Since CWP was reported by other to occur

  13. An HSV-based library screen identifies PP1α as a negative TRPV1 regulator with analgesic activity in models of pain.

    PubMed

    Reinhart, Bonnie; Goins, William F; Harel, Asaff; Chaudhry, Suchita; Goss, James R; Yoshimura, Naoki; de Groat, William C; Cohen, Justus B; Glorioso, Joseph C

    2016-01-01

    Transient receptor potential vanilloid 1 (TRPV1) is a pronociceptive cation channel involved in persistent inflammatory and neuropathic pain. Herpes simplex virus (HSV) vector expression of TRPV1 causes cell death in the presence of capsaicin, thereby completely blocking virus replication. Here we describe a selection system for negative regulators of TRPV1 based on rescue of virus replication. HSV-based coexpression of TRPV1 and a PC12 cell-derived cDNA library identified protein phosphatase 1α (PP1α) as a negative regulator of TRPV1, mimicking the activity of "poreless" (PL), a dominant-negative mutant of TRPV1. Vectors expressing PP1α or PL reduced thermal sensitivity following virus injection into rat footpads, but failed to reduce the nocifensive responses to menthol/icilin-activated cold pain or formalin, demonstrating that the activity identified in vitro is functional in vivo with a degree of specificity. This system should prove powerful for identifying other cellular factors that can inhibit ion channel activity. PMID:27382601

  14. An HSV-based library screen identifies PP1α as a negative TRPV1 regulator with analgesic activity in models of pain

    PubMed Central

    Reinhart, Bonnie; Goins, William F; Harel, Asaff; Chaudhry, Suchita; Goss, James R; Yoshimura, Naoki; de Groat, William C; Cohen, Justus B; Glorioso, Joseph C

    2016-01-01

    Transient receptor potential vanilloid 1 (TRPV1) is a pronociceptive cation channel involved in persistent inflammatory and neuropathic pain. Herpes simplex virus (HSV) vector expression of TRPV1 causes cell death in the presence of capsaicin, thereby completely blocking virus replication. Here we describe a selection system for negative regulators of TRPV1 based on rescue of virus replication. HSV-based coexpression of TRPV1 and a PC12 cell-derived cDNA library identified protein phosphatase 1α (PP1α) as a negative regulator of TRPV1, mimicking the activity of “poreless” (PL), a dominant-negative mutant of TRPV1. Vectors expressing PP1α or PL reduced thermal sensitivity following virus injection into rat footpads, but failed to reduce the nocifensive responses to menthol/icilin-activated cold pain or formalin, demonstrating that the activity identified in vitro is functional in vivo with a degree of specificity. This system should prove powerful for identifying other cellular factors that can inhibit ion channel activity. PMID:27382601

  15. Esophageal Submucosal Injection of Capsaicin but Not Acid Induces Symptoms in Normal Subjects

    PubMed Central

    Lee, Robert H; Korsapati, Hariprasad; Bhalla, Vikas; Varki, Nissi; Mittal, Ravinder K

    2016-01-01

    Background/Aims Transient receptor potential vanilloid-1 (TRPV1) is a candidate for mediating acid-induced symptoms in the esophagus. We conducted studies to determine if the presence of acid in the mucosa/submucosa and direct activation of TRPV1 by capsaicin elicited symptoms in normal healthy subjects. We also studied the presence of TRPV1 receptors in the esophagus. Methods Unsedated endoscopy was performed on healthy subjects with no symptoms. Using a sclerotherapy needle, normal saline (pH 2.0–7.5) was injected into the mucosa/submucosa, 5 cm above the Z line. In a separate group of healthy subjects, injection of capsaicin and vehicle was also studied. Quality of symptoms was reported using the McGill Pain Questionnaire, and symptom intensity using the visual analogue scale (VAS). Immunohistochemistry was performed on 8 surgical esophagus specimens using TRPV1 antibody. Results Acid injection either did not elicit or elicited mild symptoms in subjects at all pH solutions. Capsaicin but not the vehicle elicited severe heartburn/chest pain in all subjects. Mean VAS for capsaicin was 91 ± 3 and symptoms lasted for 25 ± 1 minutes. Immunohistochemistry revealed a linear TRPV1 staining pattern between the epithelial layer and the submucosa that extended into the papillae. Eighty-five percent of papillae stained positive for TRPV1 with a mean 1.1 positive papillae per high-powered field. Conclusions The mechanism of acid-induced heartburn and chest pain is not the simple interaction of hydrogen ions with afferents located in the esophageal mucosa and submucosa. TRPV1 receptors are present in the lamina propria and their activation induces heartburn and chest pain. PMID:26932896

  16. The role of the TRPV1 endogenous agonist N-Oleoyldopamine in modulation of nociceptive signaling at the spinal cord level.

    PubMed

    Spicarova, Diana; Palecek, Jiri

    2009-07-01

    Transient receptor potential vanilloid (TRPV1) receptors are abundant in a subpopulation of primary sensory neurons that convey nociceptive information from the periphery to the spinal cord dorsal horn. The TRPV1 receptors are expressed on both the peripheral and central branches of these dorsal root ganglion (DRG) neurons and can be activated by capsaicin, heat, low pH, and also by recently described endogenous lipids. Using patch-clamp recordings from superficial dorsal horn (DH) neurons in acute spinal cord slices, the effect of application of the endogenous TRPV1 agonist N-oleoyldopamine (OLDA) on the frequency of miniature excitatory postsynaptic currents (mEPSCs) was evaluated. A high concentration OLDA (10 microM) solution was needed to increase the mEPSC frequency, whereas low concentration OLDA (0.2 microM) did not evoke any change under control conditions. The increase was blocked by the TRPV1 antagonists SB366791 or BCTC. Application of a low concentration of OLDA evoked an increase in mEPSC frequency after activation of protein kinase C by phorbol ester (PMA) and bradykinin or in slices from animals with peripheral inflammation. Increasing the bath temperature from 24 to 34 degrees C enhanced the basal mEPSC frequency, but the magnitude of changes in the mEPSC frequency induced by OLDA administration was similar at both temperatures. Our results suggest that presumed endogenous agonists of TRPV1 receptors, like OLDA, could have a considerable impact on synaptic transmission in the spinal cord, especially when TRPV1 receptors are sensitized. Spinal TRPV1 receptors could play a pivotal role in modulation of nociceptive signaling in inflammatory pain. PMID:19369364

  17. Activation of the human transient receptor potential vanilloid subtype 1 by essential oils.

    PubMed

    Ohkawara, Susumu; Tanaka-Kagawa, Toshiko; Furukawa, Yoko; Nishimura, Tetsuji; Jinno, Hideto

    2010-01-01

    Transient receptor potential vanilloid subtype 1 (TRPV1) is a non-selective cation channel activated by capsaicin. TRPV1 is expressed not only on human sensory neurons but also on human epidermal and hair follicle keratinocytes. Therefore, TRPV1 could have the potential to be a therapeutic target for skin disorders. To search for novel TRPV1 agonists, we screened 31 essential oils by using human TRPV1-expressing HEK293 cells. TRPV1 was activated by 4 essential oils: rose, thyme geraniol, palmarosa, and tolu balsam. The dose-response curves for TRPV1 activation by the essential oils revealed a rank order potency [the half-maximal effective concentration (EC(50))] of rose>palmarosa>thyme geraniol>tolu balsam, and rank order efficiency (% activity in response to 1 microM capsaicin) of tolu balsam>rose>palmarosa>thyme geraniol. Moreover, the dose-response curves for TRPV1 activation by citronellol (main constituent of rose oil) and geraniol (main constituent of thyme geraniol and palmarosa oils) were consistent with the potency and efficiency of each essential oil. In contrast, benzyl cinnamate and benzyl benzoate (main constituent of tolu balsam oil) and geranyl acetate (main constituent of thyme geraniol oil) did not show TRPV1 activity. In this first-of-its-kind study, we successfully investigated the role of some essential oils in promoting human TRPV1 activation, and also identified two monoterpenes, citronellol and geraniol, as new human TRPV1 agonists. PMID:20686244

  18. TRPV1 expression level in isolectin B₄-positive neurons contributes to mouse strain difference in cutaneous thermal nociceptive sensitivity.

    PubMed

    Ono, Kentaro; Ye, Yi; Viet, Chi T; Dang, Dongmin; Schmidt, Brian L

    2015-05-01

    Differential thermal nociception across inbred mouse strains has genetic determinants. Thermal nociception is largely attributed to the heat/capsaicin receptor transient receptor potential vanilloid 1 (TRPV1); however, the contribution of this channel to the genetics of thermal nociception has not been revealed. In this study we compared TRPV1 expression levels and electrophysiological properties in primary sensory neurons and thermal nociceptive behaviors between two (C57BL/6 and BALB/c) inbred mouse strains. Using immunofluorescence and patch-clamp physiology methods, we demonstrated that TRPV1 expression was significantly higher in isolectin B4 (IB4)-positive trigeminal sensory neurons of C57BL/6 relative to BALB/c; the expression in IB4-negative neurons was similar between the strains. Furthermore, using electrophysiological cell classification (current signature method), we showed differences between the two strains in capsaicin sensitivity in IB4-positive neuronal cell types 2 and 13, which were previously reported as skin nociceptors. Otherwise electrophysiological membrane properties of the classified cell types were similar in the two mouse strains. In publicly available nocifensive behavior data and our own behavior data from the using the two mouse strains, C57BL/6 exhibited higher sensitivity to heat stimulation than BALB/c, independent of sex and anatomical location of thermal testing (the tail, hind paw, and whisker pad). The TRPV1-selective antagonist JNJ-17203212 inhibited thermal nociception in both strains; however, removing IB4-positive trigeminal sensory neurons with IB4-conjugated saporin inhibited thermal nociception on the whisker pad in C57BL/6 but not in BALB/c. These results suggest that TRPV1 expression levels in IB4-positive type 2 and 13 neurons contributed to differential thermal nociception in skin of C57BL/6 compared with BALB/c. PMID:25787958

  19. No relevant modulation of TRPV1-mediated trigeminal pain by intranasal carbon dioxide in healthy humans

    PubMed Central

    2013-01-01

    Background Nasal insufflation of CO2 has been shown to exert antinociceptive respectively antihyperalgesic effects in animal pain models using topical capsaicin with activation of TRPV1-receptor positive nociceptive neurons. Clinical benefit from CO2 inhalation in patients with craniofacial pain caused by a putative activation of TRPV1 receptor positive trigeminal neurons has also been reported. These effects are probably mediated via an activation of TRPV1 receptor - positive neurons in the nasal mucosa with subsequent central inhibitory effects (such as conditioned pain modulation). In this study, we aimed to examine the effects of intranasal CO2 on a human model of craniofacial pain elicited by nasal application of capsaicin. Methods In a first experiment, 48 healthy volunteers without previous craniofacial pain received intranasal capsaicin to provoke trigeminal pain elicited by activation of TRVP1 positive nociceptive neurons. Then, CO2 or air was insufflated alternatingly into the nasal cavity at a flow rate of 1 l/min for 60 sec each. In the subsequent experiment, all participants were randomized into 2 groups of 24 each and received either continuous nasal insufflation of CO2 or placebo for 18:40 min after nociceptive stimulation with intranasal capsaicin. In both experiments, pain was rated on a numerical rating scale every 60 sec. Results Contrary to previous animal studies, the effects of CO2 on experimental trigeminal pain were only marginal. In the first experiment, CO2 reduced pain ratings only minimally by 5.3% compared to air if given alternatingly with significant results for the main factor GROUP (F1,47 = 4.438; p = 0.041) and the interaction term TIME*GROUP (F2.6,121.2 = 3.3; p = 0.029) in the repeated-measures ANOVA. However, these effects were abrogated after continuous insufflation of CO2 or placebo with no significant changes for the main factors or the interaction term. Conclusions Although mild modulatory effects of low

  20. Unravelling the Mystery of Capsaicin: A Tool to Understand and Treat Pain

    PubMed Central

    Brock, Christina; Olesen, Anne Estrup; Andresen, Trine; Nilsson, Matias; Dickenson, Anthony H.

    2012-01-01

    A large number of pharmacological studies have used capsaicin as a tool to activate many physiological systems, with an emphasis on pain research but also including functions such as the cardiovascular system, the respiratory system, and the urinary tract. Understanding the actions of capsaicin led to the discovery its receptor, transient receptor potential (TRP) vanilloid subfamily member 1 (TRPV1), part of the superfamily of TRP receptors, sensing external events. This receptor is found on key fine sensory afferents, and so the use of capsaicin to selectively activate pain afferents has been exploited in animal studies, human psychophysics, and imaging studies. Its effects depend on the dose and route of administration and may include sensitization, desensitization, withdrawal of afferent nerve terminals, or even overt death of afferent fibers. The ability of capsaicin to generate central hypersensitivity has been valuable in understanding the consequences and mechanisms behind enhanced central processing of pain. In addition, capsaicin has been used as a therapeutic agent when applied topically, and antagonists of the TRPV1 receptor have been developed. Overall, the numerous uses for capsaicin are clear; hence, the rationale of this review is to bring together and discuss the different types of studies that exploit these actions to shed light upon capsaicin working both as a tool to understand pain but also as a treatment for chronic pain. This review will discuss the various actions of capsaicin and how it lends itself to these different purposes. PMID:23023032

  1. Protective effect of transient receptor potential vanilloid subtype 1 (TRPV1) modulator, against behavioral, biochemical and structural damage in experimental models of Alzheimer's disease.

    PubMed

    Jayant, Shalini; Sharma, B M; Sharma, Bhupesh

    2016-07-01

    Alzheime's disease (AD) is an overwhelming neurodegenerative disorder, characterized by synaptic dysfunction, memory loss, neuro-inflammation and neural cell death. Very few treatments are in hand for the management of AD and they are only concentrating on peculiar aspects. Hence, an immense thrust is required to find utmost therapeutic targets to conquer this condition. This study investigates a potential role of vanillin, a selective agonist of transient receptor potential vanilloid subtype 1 (TRPV1) in the experimental models of AD viz. intracerebroventricular (i.c.v.) streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose induced AD in mice. The i.c.v. administration of STZ and intraperitoneally administration of AlCl3+d-galactose have significantly impaired learning-memory (Morris water maze and attentional set-shifting test), brain structure (hematoxylin, eosin and Congo red staining), enhanced brain oxidative stress (thiobarbituric acid reactive substance - TBARS and glutathione - GSH), nitrosative stress (nitrite/nitrate), acetylcholinesterase activity (AChE), inflammation (MPO), and calcium levels (Ca(++)). Treatment with vanillin in different doses and donepezil have significantly ameliorated i.c.v. STZ and AlCl3+d-galactose induced reduction in executive function, impaired reversal learning, cognition, memory and brain damage. Treatment with these drugs has also reduced the brain oxidative stress (TBARS and GSH), nitrosative stress (nitrite/nitrate), and AChE, MPO, and Ca(++) levels. These results indicate that vanillin, a selective agonist of TRPV1 and donepezil, a potent acetylcholine esterase inhibitor have attenuated i.c.v. STZ and AlCl3+d-galactose induced experimental AD. Hence, pharmacological positive modulation of TRPV1 channels may be a potential research target for mitigation of AD. PMID:27084583

  2. Activation of mitochondrial transient receptor potential vanilloid 1 channel contributes to microglial migration.

    PubMed

    Miyake, Takahito; Shirakawa, Hisashi; Nakagawa, Takayuki; Kaneko, Shuji

    2015-10-01

    Microglia, the resident immune cells in the brain, survey the environment of the healthy brain. Microglial migration is essential for many physiological and pathophysiological processes. Although microglia express some members of the transient receptor potential (TRP) channel family, there is little knowledge regarding the physiological roles of TRP channels in microglia. Here, we explored the role of TRP vanilloid 1 (TRPV1), a channel opened by capsaicin, heat, protons, and endovanilloids, in microglia. We found that application of capsaicin induced concentration-dependent migration in microglia derived from wild-type mice but not in those derived from TRPV1 knockout (TRPV1-KO) mice. Capsaicin-induced microglial migration was significantly inhibited by co-application of the TRPV1 blocker SB366791 and the Ca(2+) chelator BAPTA-AM. Using RT-PCR and immunocytochemistry, we validated that TRPV1 was expressed in microglia. Electrophysiological recording, intracellular Ca(2+) imaging, and immunocytochemistry indicated that TRPV1 was localized primarily in intracellular organelles. Treatment with capsaicin induced an increase in intramitochondrial Ca(2+) concentrations and mitochondrial depolarization. Furthermore, microglia derived from TRPV1-KO mice showed delayed Ca(2+) efflux compared with microglia derived from wild-type mice. Capsaicin-induced microglial migration was inhibited by membrane-permeable antioxidants and MAPK inhibitors, suggesting that mitochondrial TRPV1 activation induced Ca(2+) -dependent production of ROS followed by MAPK activation, which correlated with an augmented migration of microglia. Moreover, a mixture of three endovanilloids augmented microglial migration via TRPV1 activation. Together, these results indicate that mitochondrial TRPV1 plays an important role in inducing microglial migration. Activation of TRPV1 triggers an increase in intramitochondrial Ca(2+) concentration and following depolarization of mitochondria, which results in mt

  3. Blockade of peripheral P2Y1 receptors prevents the induction of thermal hyperalgesia via modulation of TRPV1 expression in carrageenan-induced inflammatory pain rats: involvement of p38 MAPK phosphorylation in DRGs.

    PubMed

    Kwon, Soon-Gu; Roh, Dae-Hyun; Yoon, Seo-Yeon; Moon, Ji-Young; Choi, Sheu-Ran; Choi, Hoon-Seong; Kang, Suk-Yun; Han, Ho-Jae; Beitz, Alvin J; Lee, Jang-Hern

    2014-04-01

    Although previous reports have suggested that P2Y1 receptors (P2Y1Rs) are involved in cutaneous nociceptive signaling, it remains unclear how P2Y1Rs contribute to peripheral sensitization. The current study was designed to delineate the role of peripheral P2Y1Rs in pain and to investigate potential linkages to mitogen-activated protein kinase (MAPK) in DRGs and Transient Receptor Potential Vanilloid 1 (TRPV1) expression in a rodent inflammatory pain model. Following injection of 2% carrageenan into the hind paw, expressions of P2Y1 and TRPV1 and the phosphorylation rates of both p38 MAPK and ERK but not JNK were increased and peaked at day 2 post-injection. Blockade of peripheral P2Y1Rs by the P2Y1R antagonist, MRS2500 injection (i.pl, D0 to D2) significantly reduced the induction of thermal hyperalgesia, but not mechanical allodynia. Simultaneously, MRS2500 injections suppressed upregulated TRPV1 expression and DRG p38 phosphorylation, while pERK signaling was not affected. Furthermore, inhibition of p38 activation in the DRGs by SB203580 (a p38 inhibitor, i.t, D0 to D2) prevented the upregulation of TRPV1 and a single i.t injection of SB203580 reversed the established thermal hyperalgesia, but not mechanical allodynia. Lastly, to identify the mechanism of action of P2Y1Rs, we repeatedly injected the P2Y1 agonist, MRS2365 into the naïve rat's hind paw and observed a dose-dependent increase in TRPV1 expression and p38 MAPK phosphorylation. These data demonstrate a sequential role for P2Y1R, p38 MAPK and TRPV1 in inflammation-induced thermal hyperalgesia; thus, peripheral P2Y1Rs activation modulates p38 MAPK signaling and TRPV1 expression, which ultimately leads to the induction of thermal hyperalgesia. PMID:24333674

  4. TLR4 enhances histamine-mediated pruritus by potentiating TRPV1 activity

    PubMed Central

    2014-01-01

    Background Recent studies have indicated that Toll-like receptor 4 (TLR4), a pathogen-recognition receptor that triggers inflammatory signals in innate immune cells, is also expressed on sensory neurons, implicating its putative role in sensory signal transmission. However, the possible function of sensory neuron TLR4 has not yet been formally addressed. In this regard, we investigated the role of TLR4 in itch signal transmission. Results TLR4 was expressed on a subpopulation of dorsal root ganglia (DRG) sensory neurons that express TRPV1. In TLR4-knockout mice, histamine-induced itch responses were compromised while TLR4 activation by LPS did not directly elicit an itch response. Histamine-induced intracellular calcium signals and inward currents were comparably reduced in TLR4-deficient sensory neurons. Reduced histamine sensitivity in the TLR4-deficient neurons was accompanied by a decrease in TRPV1 activity. Heterologous expression experiments in HEK293T cells indicated that TLR4 expression enhanced capsaicin-induced intracellular calcium signals and inward currents. Conclusions Our data show that TLR4 on sensory neurons enhances histamine-induced itch signal transduction by potentiating TRPV1 activity. The results suggest that TLR4 could be a novel target for the treatment of enhanced itch sensation. PMID:25139109

  5. Agonist-dependence of functional properties for common nonsynonymous variants of human transient receptor potential vanilloid 1.

    PubMed

    Wang, Sen; Joseph, John; Diatchenko, Luda; Ro, Jin Y; Chung, Man-Kyo

    2016-07-01

    Transient receptor potential vanilloid 1 (TRPV1) is a polymodal receptor activated by capsaicin, heat, and acid, which plays critical roles in thermosensation and pain. In addition, TRPV1 also contributes to multiple pathophysiological states in respiratory, cardiovascular, metabolic, and renal systems. These contributions are further supported by evidence that variations in the human TRPV1 (hTRPV1) gene are associated with various physiological and pathological phenotypes. However, it is not well understood how the variations in hTRPV1 affect channel functions. In this study, we examined functional consequences of amino acid variations of hTRPV1 induced by 5 nonsynonymous single-nucleotide polymorphisms (SNPs) that most commonly exist in the human population. Using electrophysiological assays in HEK293 cells, we examined 9 parameters: activation, Ca permeation, and desensitization after activation by capsaicin, acid, and heat. Our results demonstrated that the 5 SNPs differentially affected functional properties of hTRPV1 in an agonist-dependent manner. Based upon the directionality of change of each phenotype and cumulative changes in each SNP, we classified the 5 SNPs into 3 presumptive functional categories: gain of function (hTRPV1 Q85R, P91S, and T469I), loss of function (I585V), and mixed (M315I). These results reveal a spectrum of functional variation among common hTRPV1 polymorphisms in humans and may aid mechanistic interpretation of phenotypes associated with nonsynonymous hTRPV1 SNPs under pathophysiological conditions. PMID:26967694

  6. Proton block of proton-activated TRPV1 current

    PubMed Central

    Lee, Bo Hyun

    2015-01-01

    The TRPV1 cation channel is a polymodal nociceptor that is activated by heat and ligands such as capsaicin and is highly sensitive to changes in extracellular pH. In the body core, where temperature is usually stable and capsaicin is normally absent, H+ released in response to ischemia, tissue injury, or inflammation is the best-known endogenous TRPV1 agonist, activating the channel to mediate pain and vasodilation. Paradoxically, removal of H+ elicits a transient increase in TRPV1 current that is much larger than the initial H+-activated current. We found that this prominent OFF response is caused by rapid recovery from H+ inhibition of the excitatory current carried by H+-activated TRPV1 channels. H+ inhibited current by interfering with ion permeation. The degree of inhibition is voltage and permeant ion dependent, and it can be affected but not eliminated by mutations to acidic residues within or near the ion selectivity filter. The opposing H+-mediated gating and permeation effects produce complex current responses under different cellular conditions that are expected to greatly affect the response of nociceptive neurons and other TRPV1-expressing cells. PMID:26170176

  7. Homocysteine and cytosolic GSH depletion induce apoptosis and oxidative toxicity through cytosolic calcium overload in the hippocampus of aged mice: involvement of TRPM2 and TRPV1 channels.

    PubMed

    Övey, I S; Naziroğlu, M

    2015-01-22

    Oxidative stress and apoptosis were induced in neuronal cultures by inhibition of glutathione (GSH) biosynthesis with d,l-buthionine-S,R-sulfoximine (BSO). Transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) cation channels are gated by oxidative stress. The oxidant effects of homocysteine (Hcy) may induce activation of TRPV1 and TRPM2 channels in aged mice as a model of Alzheimer's disease (AD). We tested the effects of Hcy, BSO and GSH on oxidative stress, apoptosis and Ca2+ and influx via TRPM2 and TRPV1 channels in the hippocampus of mice. Native mice hippocampal neurons were divided into five groups as follows; control, Hcy, BSO, Hcy+BSO and Hcy+BSO+GSH groups. The neurons in TRPM2 and TRPV1 experiments were stimulated by hydrogen peroxide and capsaicin, respectively. BSO and Hcy incubations increased intracellular free Ca2+ concentrations, reactive oxygen species, apoptosis, mitochondrial depolarization, and levels of caspase 3 and 9. All of these increases were reduced by GSH treatments. Treatment with 2-aminoethoxydiphenyl borate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA) as potent inhibitors of TRPM2, capsazepine as a potent inhibitor of TRPV1, verapamil+diltiazem (V+D) as inhibitors of the voltage-gated Ca2+ channels (VGCC) and MK-801 as a N-methyl-d-aspartate (NMDA) channel antagonist indicated that GSH depletion and Hcy elevation activated Ca2+ entry into the neurons through TRPM2, TRPV1, VGCC and NMDA channels. Inhibitor roles of 2-APB and capsazepine on the Ca2+ entry higher than in V+D and MK-801 antagonists. In conclusion, these findings support the idea that GSH depletion and Hcy elevation can have damaging effects on hippocampal neurons by perturbing calcium homeostasis, mainly through TRPM2 and TRPV1 channels. GSH treatment can partially reverse these effects. PMID:25305668

  8. Differential regulation of TRPV1 channels by H2O2: implications for diabetic microvascular dysfunction

    PubMed Central

    DelloStritto, Daniel J.; Connell, Patrick J.; Dick, Gregory M.; Fancher, Ibra S.; Klarich, Brittany; Fahmy, Joseph N.; Kang, Patrick T.; Chen, Yeong-Renn; Damron, Derek S.; Thodeti, Charles K.

    2016-01-01

    We demonstrated previously that TRPV1-dependent coupling of coronary blood flow (CBF) to metabolism is disrupted in diabetes. A critical amount of H2O2 contributes to CBF regulation; however, excessive H2O2 impairs responses. We sought to determine the extent to which differential regulation of TRPV1 by H2O2 modulates CBF and vascular reactivity in diabetes. We used contrast echocardiography to study TRPV1 knockout (V1KO), db/db diabetic, and wild type C57BKS/J (WT) mice. H2O2 dose-dependently increased CBF in WT mice, a response blocked by the TRPV1 antagonist SB366791. H2O2-induced vasodilation was significantly inhibited in db/db and V1KO mice. H2O2 caused robust SB366791-sensitive dilation in WT coronary microvessels; however, this response was attenuated in vessels from db/db and V1KO mice, suggesting H2O2-induced vasodilation occurs, in part, via TRPV1. Acute H2O2 exposure potentiated capsaicin-induced CBF responses and capsaicin-mediated vasodilation in WT mice, whereas prolonged luminal H2O2 exposure blunted capsaicin-induced vasodilation. Electrophysiology studies re-confirms acute H2O2 exposure activated TRPV1 in HEK293A and bovine aortic endothelial cells while establishing that H2O2 potentiate capsaicin-activated TRPV1 currents, whereas prolonged H2O2 exposure attenuated TRPV1 currents. Verification of H2O2-mediated activation of intrinsic TRPV1 specific currents were found in isolated mouse coronary endothelial cells from WT mice and decreased in endothelial cells from V1KO mice. These data suggest prolonged H2O2 exposure impairs TRPV1-dependent coronary vascular signaling. This may contribute to microvascular dysfunction and tissue perfusion deficits characteristic of diabetes. PMID:26907473

  9. Involvement of TRPV1 channels in the activity of the cannabinoid WIN 55,212-2 in an acute rat model of temporal lobe epilepsy.

    PubMed

    Carletti, Fabio; Gambino, Giuditta; Rizzo, Valerio; Ferraro, Giuseppe; Sardo, Pierangelo

    2016-05-01

    The exogenous cannabinoid agonist WIN 55,212-2, (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo[1,2,3-de]-1,4-benzoxazin-6-Yl]-1-naphthalenylmethanone (WIN), has revealed to play a role on modulating the hyperexcitability phenomena in the hippocampus. Cannabinoid-mediated mechanisms of neuroprotection have recently been found to imply the modulation of transient receptor potential vanilloid 1 (TRPV1), a cationic channel subfamily that regulate synaptic excitation. In our study, we assessed the influence of pharmacological manipulation of TRPV1 function, alone and on WIN antiepileptic activity, in the Maximal Dentate Activation (MDA) acute model of temporal lobe epilepsy. Our results showed that the TRPV1 agonist, capsaicin, increased epileptic outcomes; whilst antagonizing TRPV1 with capsazepine exerts a protective role on paroxysmal discharge. When capsaicin is co-administered with WIN effective dose of 10mg/kg is able to reduce its antiepileptic strength, especially on the triggering of MDA response. Accordingly, capsazepine at the protective dose of 2mg/kg managed to potentiate WIN antiepileptic effects, when co-treated. Moreover, WIN subeffective dose of 5mg/kg was turned into effective when capsazepine comes into play. This evidence suggests that systemic administration of TRPV1-active drugs influences electrically induced epilepsy, with a noticeable protective activity for capsazepine. Furthermore, results from the pharmacological interaction with WIN support an interplay between cannabinoid and TRPV1 signaling that could represent a promising approach for a future pharmacological strategy to challenge hyperexcitability-based diseases. PMID:26970948

  10. Lipopolysaccharide-induced Pulpitis Up-regulates TRPV1 in Trigeminal Ganglia

    PubMed Central

    Chung, M.-K.; Lee, J.; Duraes, G.; Ro, J.Y.

    2011-01-01

    Tooth pain often accompanies pulpitis. Accumulation of lipopolysaccharides (LPS), a product of Gram-negative bacteria, is associated with painful clinical symptoms. However, the mechanisms underlying LPS-induced tooth pain are not clearly understood. TRPV1 is a capsaicin- and heat-gated nociceptive ion channel implicated in thermosensation and hyperalgesia under inflammation or injury. Although TRPV1 is expressed in pulpal afferents, it is not known whether the application of LPS to teeth modulates TRPV1 in trigeminal nociceptors. By assessing the levels of protein and transcript of TRPV1 in mouse trigeminal ganglia, we demonstrate that dentinal application of LPS increases the expression of TRPV1. Our results suggest that the up-regulation of TRPV1 in trigeminal nociceptors following bacterial infection could contribute to hyperalgesia under pulpitis conditions. PMID:21712529

  11. Role of thermo TRPA1 and TRPV1 channels in heat, cold, and mechanical nociception of rats.

    PubMed

    Nozadze, Ivliane; Tsiklauri, Nana; Gurtskaia, Gulnazi; Tsagareli, Merab G

    2016-02-01

    A sensitive response of the nervous system to changes in temperature is of predominant importance for homeotherms to maintain a stable body temperature. A number of temperature-sensitive transient receptor potential (TRP) ion channels have been studied as nociceptors that respond to extreme temperatures and harmful chemicals. Recent findings in the field of pain have established a family of six thermo-TRP channels (TRPA1, TRPM8, TRPV1, TRPV2, TRPV3, and TRPV4) that exhibit sensitivity to increases or decreases in temperature, as well as to chemical substances eliciting the respective hot or cold sensations. In this study, we used behavioral methods to investigate whether mustard oil (allyl isothiocyanate) and capsaicin affect the sensitivity to heat, innocuous and noxious cold, and mechanical stimuli in male rats. The results obtained indicate that TRPA1 and TRPV1 channels are clearly involved in pain reactions, and the TRPA1 agonist allyl isothiocyanate enhances the heat pain sensitivity, possibly by indirectly modulating TRPV1 channels coexpressed in nociceptors with TRPA1. Overall, our data support the role of thermosensitive TRPA1 and TRPV1 channels in pain modulation and show that these two thermoreceptor channels are in a synergistic and/or conditional relationship with noxious heat and cold cutaneous stimulation. PMID:26274042

  12. Different types of toxins targeting TRPV1 in pain.

    PubMed

    Min, Jia-Wei; Liu, Wan-Hong; He, Xiao-Hua; Peng, Bi-Wen

    2013-09-01

    The transient receptor potential vanilloid 1(TRPV1) channels are members of the transient receptor potential (TRP) superfamily. Members of this family are expressed in primary sensory neurons and are best known for their role in nociception and sensory transmission. Multiple painful stimuli can activate these channels. In this review, we discussed the mechanisms of different types of venoms that target TRPV1, such as scorpion venom, botulinum neurotoxin, spider toxin, ciguatera fish poisoning (CFP) and neurotoxic shellfish poisoning (NSP). Some of these toxins activate TRPV1; however, some do not. Regardless of TRPV1 inhibition or activation, they occur through different pathways. For example, BoNT/A decreases TRPV1 expression levels by blocking TRPV1 trafficking to the plasma membrane, although the exact mechanism is still under debate. Vanillotoxins from tarantula (Psalmopoeus cambridgei) are proposed to activate TRPV1 via interaction with a region of TRPV1 that is homologous to voltage-dependent ion channels. Here, we offer a description of the present state of knowledge for this complex subject. PMID:23732125

  13. CT-guided injection of a TRPV1 agonist around dorsal root ganglia decreases pain transmission in swine

    PubMed Central

    Brown, Jacob D.; Saeed, Maythem; Do, Loi; Braz, Joao; Basbaum, Allan I.; Iadarola, Michael J.; Wilson, David M.; Dillon, William P.

    2016-01-01

    One approach to analgesia is to block pain at the site of origin or along the peripheral pathway by selectively ablating pain-transmitting neurons or nerve terminals directly. The heat/capsaicin receptor (TRPV1) expressed by nociceptive neurons is a compelling target for selective interventional analgesia because it leaves somatosensory and proprioceptive neurons intact. Resiniferatoxin (RTX), like capsaicin, is a TRPV1 agonist but has greater potency. We combine RTX-mediated inactivation with the precision of computed tomography (CT)–guided delivery to ablate peripheral pain fibers in swine. Under CT guidance, RTX was delivered unilaterally around the lumbar dorsal root ganglia (DRG), and vehicle only was administered to the contralateral side. During a 4-week observation period, animals demonstrated delayed or absent withdrawal responses to infrared laser heat stimuli delivered to sensory dermatomes corresponding to DRG receiving RTX treatment. Motor function was unimpaired as assessed by disability scoring and gait analysis. In treated DRG, TRPV1 mRNA expression was reduced, as were nociceptive neuronal perikarya in ganglia and their nerve terminals in the ipsilateral dorsal horn. CT guidance to precisely deliver RTX to sites of peripheral pain transmission in swine may be an approach that could be tailored to block an array of clinical pain conditions in patients. PMID:26378245

  14. Cigarette smoke has sensory effects through nicotinic and TRPA1 but not TRPV1 receptors on the isolated mouse trachea and larynx.

    PubMed

    Kichko, Tatjana I; Kobal, Gerd; Reeh, Peter W

    2015-10-15

    Cigarette smoke (CS) exposes chemosensory nerves in the airways to a multitude of chemicals, some acting through the irritant receptors TRPV1 and TRPA1 but potentially also through nicotinic acetylcholine receptors (nAChR). Our aim was to characterize the differences in sensory neuronal effects of CS, gas phase, and particulate matter as well as of typical constituents, such as nicotine and reactive carbonyls. Isolated mouse trachea and larynx were employed to measure release of calcitonin gene-related peptide (CGRP) as an index of sensory neuron activation evoked by CS, by filtered CS gas phase essentially free of nicotine, and by dilute total particulate matter (TPM) containing defined nicotine concentrations. With CS stimulation of the superfused trachea, TRPV1 null mutants showed about the same large responses as wild-type mice, whereas both TRPA1(-/-) and double knockouts exhibited 80% reduction; the retained 20% response was abolished by mecamylamine (10 μM), indicating a distinct contribution of nAChRs. These phenotypes were accentuated by using TPM to stimulate the immersed trachea; 50% of response was retained in TRPA1(-/-) and abolished by mecamylamine. In contrast, the gas phase acted like a sheer TRPA1 agonist, consistent with its composition, among other compounds, of volatile reactive carbonyls like formaldehyde and acrolein. In the trachea, the gas phase and CS were equally effective in releasing CGRP, whereas the larynx showed much larger CS than gas phase responses. Thus nicotinic receptors contribute to the sensory effects of cigarette smoke on the trachea, which are dominated by TRPA1. How this translates to human perception affords future research. PMID:26472811

  15. Cigarette smoke has sensory effects through nicotinic and TRPA1 but not TRPV1 receptors on the isolated mouse trachea and larynx

    PubMed Central

    Kichko, Tatjana I.; Kobal, Gerd

    2015-01-01

    Cigarette smoke (CS) exposes chemosensory nerves in the airways to a multitude of chemicals, some acting through the irritant receptors TRPV1 and TRPA1 but potentially also through nicotinic acetylcholine receptors (nAChR). Our aim was to characterize the differences in sensory neuronal effects of CS, gas phase, and particulate matter as well as of typical constituents, such as nicotine and reactive carbonyls. Isolated mouse trachea and larynx were employed to measure release of calcitonin gene-related peptide (CGRP) as an index of sensory neuron activation evoked by CS, by filtered CS gas phase essentially free of nicotine, and by dilute total particulate matter (TPM) containing defined nicotine concentrations. With CS stimulation of the superfused trachea, TRPV1 null mutants showed about the same large responses as wild-type mice, whereas both TRPA1−/− and double knockouts exhibited 80% reduction; the retained 20% response was abolished by mecamylamine (10 μM), indicating a distinct contribution of nAChRs. These phenotypes were accentuated by using TPM to stimulate the immersed trachea; 50% of response was retained in TRPA1−/− and abolished by mecamylamine. In contrast, the gas phase acted like a sheer TRPA1 agonist, consistent with its composition, among other compounds, of volatile reactive carbonyls like formaldehyde and acrolein. In the trachea, the gas phase and CS were equally effective in releasing CGRP, whereas the larynx showed much larger CS than gas phase responses. Thus nicotinic receptors contribute to the sensory effects of cigarette smoke on the trachea, which are dominated by TRPA1. How this translates to human perception affords future research. PMID:26472811

  16. Nicotinic acid is a common regulator of heat-sensing TRPV1-4 ion channels.

    PubMed

    Ma, Linlin; Lee, Bo Hyun; Clifton, Heather; Schaefer, Saul; Zheng, Jie

    2015-01-01

    Nicotinic acid (NA, a.k.a. vitamin B3 or niacin) can reduce blood cholesterol and low-density lipoproteins whereas increase high-density lipoproteins. However, when NA is used to treat dyslipidemias, it causes a strong side effect of cutaneous vasodilation, commonly called flushing. A recent study showed that NA may cause flushing by lowering activation threshold temperature of the heat-sensitive capsaicin receptor TRPV1 ion channel, leading to its activation at body temperature. The finding calls into question whether NA might also interact with the homologous heat-sensitive TRPV2-4 channels, particularly given that TRPV3 and TRPV4 are abundantly expressed in keratinocytes of the skin where much of the flushing response occurs. We found that NA indeed potentiated TRPV3 while inhibited TRPV2 and TRPV4. Consistent with these gating effects, NA lowered the heat-activation threshold of TRPV3 but elevated that of TRPV4. We further found that activity of TRPV1 was substantially prolonged by extracellular NA, which may further enhance the direct activation effect. Consistent with the broad gating effect on TRPV1-4 channels, evidence from the present study hints that NA may share the same activation pathway as 2-aminoethoxydiphenyl borate (2-APB), a common agonist for these TRPV channels. These findings shed new light on the molecular mechanism underlying NA regulation of TRPV channels. PMID:25752528

  17. Nicotinic Acid is a Common Regulator of Heat-Sensing TRPV1-4 Ion Channels

    PubMed Central

    Ma, Linlin; Lee, Bo Hyun; Clifton, Heather; Schaefer, Saul; Zheng, Jie

    2015-01-01

    Nicotinic acid (NA, a.k.a. vitamin B3 or niacin) can reduce blood cholesterol and low-density lipoproteins whereas increase high-density lipoproteins. However, when NA is used to treat dyslipidemias, it causes a strong side effect of cutaneous vasodilation, commonly called flushing. A recent study showed that NA may cause flushing by lowering activation threshold temperature of the heat-sensitive capsaicin receptor TRPV1 ion channel, leading to its activation at body temperature. The finding calls into question whether NA might also interact with the homologous heat-sensitive TRPV2–4 channels, particularly given that TRPV3 and TRPV4 are abundantly expressed in keratinocytes of the skin where much of the flushing response occurs. We found that NA indeed potentiated TRPV3 while inhibited TRPV2 and TRPV4. Consistent with these gating effects, NA lowered the heat-activation threshold of TRPV3 but elevated that of TRPV4. We further found that activity of TRPV1 was substantially prolonged by extracellular NA, which may further enhance the direct activation effect. Consistent with the broad gating effect on TRPV1–4 channels, evidence from the present study hints that NA may share the same activation pathway as 2-aminoethoxydiphenyl borate (2-APB), a common agonist for these TRPV channels. These findings shed new light on the molecular mechanism underlying NA regulation of TRPV channels. PMID:25752528

  18. Nerve fibers that were not stained with the non-specific acetylcholinesterase (NsAchE) method, and TRPV1- and IB4-positive nerve fibers in the rat cornea.

    PubMed

    Nakagawa, Hiroshi; Hiura, Akio; Mitome, Masato; Ishimura, Kazunori

    2009-08-01

    Previously, we noticed the presence of nerve fiber-like structures in a whole mount preparation of the rat cornea that had not been stained with the non-specific acetylcholinesterase (NsAchE) method. These nerve-like fibers were projected into the central area of the cornea, forming a mesh-like pattern. The aim of this study is to examine the properties of these mesh-like fibers using the following two methods: their sensitivity to capsaicin and the detection of isolectin B4 (IB4)- and capsaicin receptor TRPV1 (transient receptor potential vanilloid 1)-reactivities. The mean disappeared area of non-stained fibers after NsAchE treatment was 26% of the total areas in the neonatally capsaicin-treated cornea. Bunches composed of fine IB4-positive nerve fibers were seen in a whole mount preparation. There were connections between the bunches, producing a mesh-like pattern similar to that of the fibers that were not stained with NsAchE. Fine TRPV1-immunoreactive (ir) nerve fibers were also shown to form bunches, with connections between each bunch observed in whole mount preparations. Thus, TRPV1-ir nerve fibers seem to densely innervate the rat corneal subepithelial stroma and are distinct from the NsAchE-positive nerve fibers. The TRPV1-ir fine nerve fibers overlapped with the IB4-positive nerve fibers, suggesting that the mesh-like fibers that were not stained with NsAchE are fine nociceptive sensory nerve fibers because of their sensitivity to capsaicin and similar distribution pattern to IB4- and TRPV1-positive nerve fibers. PMID:19763029

  19. Involvement of the TRPV1 channel in the modulation of spontaneous locomotor activity, physical performance and physical exercise-induced physiological responses.

    PubMed

    Hudson, A S R; Kunstetter, A C; Damasceno, W C; Wanner, S P

    2016-01-01

    Physical exercise triggers coordinated physiological responses to meet the augmented metabolic demand of contracting muscles. To provide adequate responses, the brain must receive sensory information about the physiological status of peripheral tissues and organs, such as changes in osmolality, temperature and pH. Most of the receptors involved in these afferent pathways express ion channels, including transient receptor potential (TRP) channels, which are usually activated by more than one type of stimulus and are therefore considered polymodal receptors. Among these TRP channels, the TRPV1 channel (transient receptor potential vanilloid type 1 or capsaicin receptor) has well-documented functions in the modulation of pain sensation and thermoregulatory responses. However, the TRPV1 channel is also expressed in non-neural tissues, suggesting that this channel may perform a broad range of functions. In this review, we first present a brief overview of the available tools for studying the physiological roles of the TRPV1 channel. Then, we present the relationship between the TRPV1 channel and spontaneous locomotor activity, physical performance, and modulation of several physiological responses, including water and electrolyte balance, muscle hypertrophy, and metabolic, cardiovascular, gastrointestinal, and inflammatory responses. Altogether, the data presented herein indicate that the TPRV1 channel modulates many physiological functions other than nociception and thermoregulation. In addition, these data open new possibilities for investigating the role of this channel in the acute effects induced by a single bout of physical exercise and in the chronic effects induced by physical training. PMID:27191606

  20. Involvement of the TRPV1 channel in the modulation of spontaneous locomotor activity, physical performance and physical exercise-induced physiological responses

    PubMed Central

    Hudson, A.S.R.; Kunstetter, A.C.; Damasceno, W.C.; Wanner, S.P.

    2016-01-01

    Physical exercise triggers coordinated physiological responses to meet the augmented metabolic demand of contracting muscles. To provide adequate responses, the brain must receive sensory information about the physiological status of peripheral tissues and organs, such as changes in osmolality, temperature and pH. Most of the receptors involved in these afferent pathways express ion channels, including transient receptor potential (TRP) channels, which are usually activated by more than one type of stimulus and are therefore considered polymodal receptors. Among these TRP channels, the TRPV1 channel (transient receptor potential vanilloid type 1 or capsaicin receptor) has well-documented functions in the modulation of pain sensation and thermoregulatory responses. However, the TRPV1 channel is also expressed in non-neural tissues, suggesting that this channel may perform a broad range of functions. In this review, we first present a brief overview of the available tools for studying the physiological roles of the TRPV1 channel. Then, we present the relationship between the TRPV1 channel and spontaneous locomotor activity, physical performance, and modulation of several physiological responses, including water and electrolyte balance, muscle hypertrophy, and metabolic, cardiovascular, gastrointestinal, and inflammatory responses. Altogether, the data presented herein indicate that the TPRV1 channel modulates many physiological functions other than nociception and thermoregulation. In addition, these data open new possibilities for investigating the role of this channel in the acute effects induced by a single bout of physical exercise and in the chronic effects induced by physical training. PMID:27191606

  1. Novel endogenous N-acyl amides activate TRPV1-4 receptors, BV-2 microglia, and are regulated in brain in an acute model of inflammation

    PubMed Central

    Raboune, Siham; Stuart, Jordyn M.; Leishman, Emma; Takacs, Sara M.; Rhodes, Brandon; Basnet, Arjun; Jameyfield, Evan; McHugh, Douglas; Widlanski, Theodore; Bradshaw, Heather B.

    2014-01-01

    A family of endogenous lipids, structurally analogous to the endogenous cannabinoid, N-arachidonoyl ethanolamine (Anandamide), and called N-acyl amides have emerged as a family of biologically active compounds at TRP receptors. N-acyl amides are constructed from an acyl group and an amine via an amide bond. This same structure can be modified by changing either the fatty acid or the amide to form potentially hundreds of lipids. More than 70 N-acyl amides have been identified in nature. We have ongoing studies aimed at isolating and characterizing additional members of the family of N-acyl amides in both central and peripheral tissues in mammalian systems. Here, using a unique in-house library of over 70 N-acyl amides we tested the following three hypotheses: (1) Additional N-acyl amides will have activity at TRPV1-4, (2) Acute peripheral injury will drive changes in CNS levels of N-acyl amides, and (3) N-acyl amides will regulate calcium in CNS-derived microglia. Through these studies, we have identified 20 novel N-acyl amides that collectively activate (stimulating or inhibiting) TRPV1-4. Using lipid extraction and HPLC coupled to tandem mass spectrometry we showed that levels of at least 10 of these N-acyl amides that activate TRPVs are regulated in brain after intraplantar carrageenan injection. We then screened the BV2 microglial cell line for activity with this N-acyl amide library and found overlap with TRPV receptor activity as well as additional activators of calcium mobilization from these lipids. Together these data provide new insight into the family of N-acyl amides and their roles as signaling molecules at ion channels, in microglia, and in the brain in the context of inflammation. PMID:25136293

  2. Role of TRPV1 channels of the dorsal periaqueductal gray in the modulation of nociception and open elevated plus maze-induced antinociception in mice.

    PubMed

    Mascarenhas, Diego Cardozo; Gomes, Karina Santos; Nunes-de-Souza, Ricardo Luiz

    2015-10-01

    Recent findings have identified the presence of transient receptor potential vanilloid-1 (TRPV1) channels within the dorsal portion of the periaqueductal gray (dPAG), suggesting their involvement in the control of pain and environmentally-induced antinociception. Environmentally, antinociception may be achieved through the use of an open elevated plus maze (oEPM, an EPM with 4 open arms), a highly aversive environmental situation. Here, we investigated the role of these TRPV1 channels within the dPAG in the modulation of a tonic pain and in the oEPM-induced antinociception. Male Swiss mice, under the nociceptive effect of 2.5% formalin injected into the right hind paw, received intra-dPAG injections of the TRPV1 agonist (capsaicin: 0, 0.01, 0.1 or 1.0 nmol/0.2 μL; Experiment 1) or antagonist (capsazepine: 0, 10 or 30 nmol/0.2 μL; Experiment 2) or combined injections of capsazepine (30 nmol) and capsaicin (1.0 nmol) (Experiment 3) and the time spent licking the formalin-injected paw was recorded. In Experiment 4, mice received intra-dPAG capsazepine (0 or 30 nmol) and were exposed to the oEPM or to a control situation, an enclosed EPM (eEPM; an EPM with 4 enclosed arms). Results showed that while capsaicin (1 nmol) decreased the time spent licking the formalin-injected paw, capsazepine did not change nociceptive response. Capsazepine (30 nmol) blocked pain inhibition induced by capsaicin and mildly attenuated the oEPM-induced antinociception. Our results revealed an important role of TRPV1 channels within the dPAG in the modulation of pain and in the phenomenon known as fear-induced antinociception in mice. PMID:26183651

  3. Sphingosine 1-phosphate to p38 signaling via S1P1 receptor and Gαi/o evokes augmentation of capsaicin-induced ionic currents in mouse sensory neurons.

    PubMed

    Langeslag, Michiel; Quarta, Serena; Leitner, Michael G; Kress, Michaela; Mair, Norbert

    2014-01-01

    The perception of painful thermal stimuli by sensory neurons is largely mediated by TRPV1. Upon tissue injury or inflammation, S1P is secreted by thrombocytes as part of an inflammatory cocktail, which sensitizes nociceptive neurons towards thermal stimuli. S1P acts on G-protein coupled receptors that are expressed in sensory neurons and sensitize TRPV1 channels towards thermal stimuli. In this study, the S1P mediated signaling pathway required for sensitization of TRPV1 channels was explored.The capsaicin induced peak inward current (ICAPS) of sensory neurons was significantly increased after S1P stimulation within minutes after application. The potentiation of ICAPS resulted from activation of Gαi through G-protein coupled receptors for S1P. Consequently, Gαi led to a signaling cascade, involving phosphoinositide-3-kinase (PI3K) and protein kinase C, which augmented ICAPS in nociceptive neurons. The S1P1 receptor agonist SEW2871 resulted in activation of the same signaling pathway and potentiation of ICAPS. Furthermore, the mitogen-activated protein kinase p38 was phosphorylated after S1P stimulation and inhibition of p38 signaling by SB203580 prevented the S1P-induced ICAPS potentiation. The current data suggest that S1P sensitized ICAPS through G-protein coupled S1P1 receptor activation of Gαi-PI3K-PKC-p38 signaling pathway in sensory neurons. PMID:25431213

  4. Role of calcium ions in the positive interaction between TRPA1 and TRPV1 channels in bronchopulmonary sensory neurons.

    PubMed

    Hsu, Chun-Chun; Lee, Lu-Yuan

    2015-06-15

    Both transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are abundantly expressed in bronchopulmonary C-fiber sensory nerves and can be activated by a number of endogenous inflammatory mediators. A recent study has reported a synergistic effect of simultaneous TRPA1 and TRPV1 activations in vagal pulmonary C-fiber afferents in anesthetized rats, but its underlying mechanism was not known. This study aimed to characterize a possible interaction between these two TRP channels and to investigate the potential role of Ca(2+) as a mediator of this interaction in isolated rat vagal pulmonary sensory neurons. Using the perforated patch-clamp recording technique, our study demonstrated a distinct positive interaction occurring abruptly between TRPA1 and TRPV1 when they were activated simultaneously by their respective agonists, capsaicin (Cap) and allyl isothiocyanate (AITC), at near-threshold concentrations in these neurons. AITC at this low concentration evoked only minimal or undetectable responses, but it markedly amplified the Cap-evoked current in the same neurons. This potentiating effect was eliminated when either AITC or Cap was replaced by non-TRPA1 and non-TRPV1 chemical activators of these neurons, demonstrating the selectivity of the interaction between these two TRP channels. Furthermore, when Ca(2+) was removed from the extracellular solution, the synergistic effect of Cap and AITC on pulmonary sensory neurons was completely abrogated, clearly indicating a critical role of Ca(2+) in mediating the action. These results suggest that this TRPA1-TRPV1 interaction may play a part in regulating the sensitivity of pulmonary sensory neurons during airway inflammatory reaction. PMID:25858491

  5. Phenotyping the Function of TRPV1-Expressing Sensory Neurons by Targeted Axonal Silencing

    PubMed Central

    Brenneis, Christian; Kistner, Katrin; Puopolo, Michelino; Segal, David; Roberson, David; Sisignano, Marco; Labocha, Sandra; Ferreirós, Nerea; Strominger, Amanda; Cobos, Enrique J.; Ghasemlou, Nader; Geisslinger, Gerd; Reeh, Peter W.; Bean, Bruce P.; Woolf, Clifford J.

    2013-01-01

    Specific somatosensations may be processed by different subsets of primary afferents. C-fibers expressing heat-sensitive TRPV1 channels are proposed, for example, to be heat but not mechanical pain detectors. To phenotype in rats the sensory function of TRPV1+ afferents, we rapidly and selectively silenced only their activity, by introducing the membrane-impermeant sodium channel blocker QX-314 into these axons via the TRPV1 channel pore. Using tandem mass spectrometry we show that upon activation with capsaicin, QX-314 selectively accumulates in the cytosol only of TRPV1-expressing cells, and not in control cells. Exposure to QX-314 and capsaicin induces in small DRG neurons a robust sodium current block within 30 s. In sciatic nerves, application of extracellular QX-314 with capsaicin persistently reduces C-fiber but not A-fiber compound action potentials and this effect does not occur in TRPV1−/− mice. Behavioral phenotyping after selectively silencing TRPV1+ sciatic nerve axons by perineural injections of QX-314 and capsaicin reveals deficits in heat and mechanical pressure but not pinprick or light touch perception. The response to intraplantar capsaicin is substantially reduced, as expected. During inflammation, silencing TRPV1+ axons abolishes heat, mechanical, and cold hyperalgesia but tactile and cold allodynia remain following peripheral nerve injury. These results indicate that TRPV1-expressing sensory neurons process particular thermal and mechanical somatosensations, and that the sensory channels activated by mechanical and cold stimuli to produce pain in naive/inflamed rats differ from those in animals after peripheral nerve injury. PMID:23283344

  6. Neuroprotection induced by N-acetylcysteine against cytosolic glutathione depletion-induced Ca2+ influx in dorsal root ganglion neurons of mice: role of TRPV1 channels.

    PubMed

    Nazıroğlu, M; Ciğ, B; Ozgül, C

    2013-07-01

    Glutathione (GSH) and N-acetylcysteine (NAC) are thiol-containing antioxidants, and also act through a direct reaction with free radicals. Transient receptor potential vanilloid 1 (TRPV1) is the principal transduction channel serving as a polymodal detector. Despite the importance of oxidative stress in pain sensitivity, its role in TRPV1 modulation is poorly understood. NAC may also have a regulator role on TRPV1 channel activity in the dorsal root ganglion (DRG) neuron. Therefore, we tested the effects of GSH and NAC on TRPV1 channel current, Ca(2+) influx, oxidative stress and caspase activity in the DRG of mice. DRG neurons were freshly isolated from mice and the neurons were incubated for 6 and 24h with buthionine sulfoximine (BSO). Pretreatment of cultured DRG neurons with NAC, results in a protection against oxidative damages. This neuroprotection is associated with the attenuation of a Ca(2+) influx triggered by oxidative agents such as H2O2, 5,5'-dithiobis-(2-nitrobenzoic acid) and GSH depletion via BSO. Here, we demonstrate the contribution of cytosolic factors (related to thiol group depletion) on the activation of TRPV1 channels in this mechanism. TRPV1 channels are activated by various agents including capsaicin (CAP), the pungent component of hot chili peppers, and are blocked by capsazepine. An oxidative environment also increased CAP-evoked TRPV1 currents in the neurons. When NAC and GSH were included in the patch pipette as well as extracellularly in the chamber, TRPV1 channels were not activated by CAP and H2O2. TRPV1 inhibitors, 2-aminoethyl diphenylborinate and N-(p-amylcinnamoyl)anthranilic acid strongly reduced BSO-induced oxidative toxicity and Ca(2+) influx, in a manner similar to pretreatment with NAC and GSH. Caspase-3 and -9 activities of all groups were not changed by the agonists or antagonists. In conclusion, in our experimental model, TRPV1 channels are involved in the oxidative stress-induced neuronal death, and negative modulation

  7. Chronic alteration in phosphatidylinositol 4,5-bisphosphate levels regulates capsaicin and mustard oil responses

    PubMed Central

    Patil, Mayur J.; Belugin, Sergei; Akopian, Armen N.

    2011-01-01

    There is an agreement that acute (in minutes) hydrolysis and accumulation of phosphatidylinositol 4,5-bisphosphate (PIP2) modulate TRPV1 and TRPA1 activities. Since inflammation results in PIP2 depletion, persisting for long periods (hours-to-days) in pain models and in clinic, we examined whether chronic depletion and accumulation of PIP2 affects capsaicin and mustard oil responses. In addition we also wanted to evaluate whether the effects of PIP2 depend on TRPV1 and TRPA1 co-expression, and whether the PIP2 actions vary in expression cells versus sensory neurons. Chronic PIP2 production was stimulated by over-expression of phosphatidylinositol-4-phosphate-5-kinase, while PIP2-specific phospholipid 5′-phosphatase was selected to reduce plasma membrane levels of PIP2. Our results demonstrate that capsaicin (100 nM; CAP) responses and receptor tachyphylaxis are not significantly influenced by chronic changes in PIP2 levels in wild-type (WT) or TRPA1 null-mutant sensory neurons, as well as CHO cells expressing TRPV1 alone or with TRPA1. However, low concentrations of CAP (20 nM) produced a higher response after PIP2 depletion in cells containing TRPV1 alone, but not TRPV1 together with TRPA1. Mustard oil (25 μM; MO) responses were also not affected by PIP2 in WT sensory neurons and cells co-expressing TRPA1 and TRPV1. In contrast, PIP2 reduction leads to pronounced tachyphylaxis to MO in cells with both channels. Chronic effect of PIP2 on TRPA1 activity depends on presence of the TRPV1 channel and cell type (CHO vs. sensory neurons). In summary, chronic alterations in PIP2 levels regulate magnitude of CAP and MO responses, as well as MO-tachyphylaxis. This regulation depends on co-expression profile of TRPA1 and TRPV1 and cell type. PMID:21337373

  8. A-425619 [1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea], a novel and selective transient receptor potential type V1 receptor antagonist, blocks channel activation by vanilloids, heat, and acid.

    PubMed

    El Kouhen, Rachid; Surowy, Carol S; Bianchi, Bruce R; Neelands, Torben R; McDonald, Heath A; Niforatos, Wende; Gomtsyan, Arthur; Lee, Chih-Hung; Honore, Prisca; Sullivan, James P; Jarvis, Michael F; Faltynek, Connie R

    2005-07-01

    The vanilloid receptor transient receptor potential type V1 (TRPV1) integrates responses to multiple stimuli, such as capsaicin, acid, heat, and endovanilloids and plays an important role in the transmission of inflammatory pain. Here, we report the identification and in vitro characterization of A-425619 [1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea], a novel, potent, and selective TRPV1 antagonist. A-425619 was found to potently block capsaicin-evoked increases in intracellular calcium concentrations in HEK293 cells expressing recombinant human TRPV1 receptors (IC50 = 5 nM). A-425619 showed similar potency (IC50 = 3-4 nM) to block TRPV1 receptor activation by anandamide and N-arachidonoyl-dopamine. Electrophysiological experiments showed that A-425619 also potently blocked the activation of native TRPV1 channels in rat dorsal root ganglion neurons (IC50 = 9 nM). When compared with other known TRPV1 antagonists, A-425619 exhibited superior potency in blocking both naive and phorbol ester-sensitized TRPV1 receptors. Like capsazepine, A-425619 demonstrated competitive antagonism (pA2 = 2.5 nM) of capsaicin-evoked calcium flux. Moreover, A-425619 was 25- to 50-fold more potent than capsazepine in blocking TRPV1 activation. A-425619 showed no significant interaction with a wide range of receptors, enzymes, and ion channels, indicating a high degree of selectivity for TRPV1 receptors. These data show that A-425619 is a structurally novel, potent, and selective TRPV1 antagonist. PMID:15837819

  9. A re-evaluation of 9-HODE activity at TRPV1 channels in comparison with anandamide: enantioselectivity and effects at other TRP channels and in sensory neurons

    PubMed Central

    De Petrocellis, Luciano; Schiano Moriello, Aniello; Imperatore, Roberta; Cristino, Luigia; Starowicz, Katarzyna; Di Marzo, Vincenzo

    2012-01-01

    Background and Purpose Two oxidation products of linoleic acid, 9- and 13-hydroxy-octadecadienoic acids (HODEs), have recently been suggested to act as endovanilloids, that is, endogenous agonists of transient receptor potential vanilloid-1 (TRPV1) channels, thereby contributing to inflammatory hyperalgesia in rats. However, HODE activity at rat TRPV1 in comparison with the best established endovanilloid, anandamide, and its enantioselectivity and selectivity towards other TRP channels that are also abundant in sensory neurons have never been investigated. Experimental Approach We studied the effect of 9(R)-HODE, 9(S)-HODE, (+/–)13-HODE, 15(S)-hydroxyanandamide and anandamide on [Ca2+]i in HEK-293 cells stably expressing the rat or human recombinant TRPV1, or rat recombinant TRPV2, TRPA1 or TRPM8, and also the effect of 9(S)-HODE in rat dorsal root ganglion (DRG) neurons by calcium imaging. Key Results Anandamide and 15(S)-hydroxyanandamide were the most potent endovanilloids at human TRPV1, whereas 9(S)-HODE was approximately threefold less efficacious and 75- and 3-fold less potent, respectively, and did not perform much better at rat TRPV1. The 9(R)-HODE and (+/–)13-HODE were almost inactive at TRPV1. Unlike anandamide and 15(S)-hydroxyanandamide, all HODEs were very weak at desensitizing TRPV1 to the action of capsaicin, but activated rat TRPV2 [only (+/–)13-HODE] and rat TRPA1, and antagonized rat TRPM8, at concentrations higher than those required to activate TRPV1. Finally, 9(S)-HODE elevated [Ca2+]i in DRG neurons almost exclusively in capsaicin-sensitive cells but only at concentrations between 25 and 100 μM. Conclusions and Implications The present data suggest that HODEs are less important endovanilloids than anandamide. Linked Articles This article is part of a themed section on Cannabinoids. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.167.issue-8 PMID:22861649

  10. (R)-(5-tert-butyl-2,3-dihydro-1H-inden-1-yl)-3-(1H-indazol-4-yl)-urea (ABT-102) blocks polymodal activation of transient receptor potential vanilloid 1 receptors in vitro and heat-evoked firing of spinal dorsal horn neurons in vivo.

    PubMed

    Surowy, Carol S; Neelands, Torben R; Bianchi, Bruce R; McGaraughty, Steve; El Kouhen, Rachid; Han, Ping; Chu, Katharine L; McDonald, Heath A; Vos, Melissa; Niforatos, Wende; Bayburt, Erol K; Gomtsyan, Arthur; Lee, Chih-Hung; Honore, Prisca; Sullivan, James P; Jarvis, Michael F; Faltynek, Connie R

    2008-09-01

    The transient receptor potential vanilloid (TRPV) 1 receptor, a nonselective cation channel expressed on peripheral sensory neurons and in the central nervous system, plays a key role in pain. TRPV1 receptor antagonism is a promising approach for pain management. In this report, we describe the pharmacological and functional characteristics of a structurally novel TRPV1 antagonist, (R)-(5-tert-butyl-2,3-dihydro-1H-inden-1-yl)-3-(1H-indazol-4-yl)-urea (ABT-102), which has entered clinical trials. At the recombinant human TRPV1 receptor ABT-102 potently (IC(50) = 5-7 nM) inhibits agonist (capsaicin, N-arachidonyl dopamine, anandamide, and proton)-evoked increases in intracellular Ca(2+) levels. ABT-102 also potently (IC(50) = 1-16 nM) inhibits capsaicin-evoked currents in rat dorsal root ganglion (DRG) neurons and currents evoked through activation of recombinant rat TRPV1 currents by capsaicin, protons, or heat. ABT-102 is a competitive antagonist (pA(2) = 8.344) of capsaicin-evoked increased intracellular Ca(2+) and shows high selectivity for blocking TRPV1 receptors over other TRP receptors and a range of other receptors, ion channels, and transporters. In functional studies, ABT-102 blocks capsaicin-evoked calcitonin gene-related peptide release from rat DRG neurons. Intraplantar administration of ABT-102 blocks heat-evoked firing of wide dynamic range and nociceptive-specific neurons in the spinal cord dorsal horn of the rat. This effect is enhanced in a rat model of inflammatory pain induced by administration of complete Freund's adjuvant. Therefore, ABT-102 potently blocks multiple modes of TRPV1 receptor activation and effectively attenuates downstream consequences of receptor activity. ABT-102 is a novel and selective TRPV1 antagonist with pharmacological and functional properties that support its advancement into clinical studies. PMID:18515644

  11. Direct action of capsaicin in brown adipogenesis and activation of brown adipocytes.

    PubMed

    Kida, Ryosuke; Yoshida, Hirofumi; Murakami, Masaru; Shirai, Mitsuyuki; Hashimoto, Osamu; Kawada, Teruo; Matsui, Tohru; Funaba, Masayuki

    2016-01-01

    The ingestion of capsaicin, the principle pungent component of red and chili peppers, induces thermogenesis, in part, through the activation of brown adipocytes expressing genes related to mitochondrial biogenesis and uncoupling such as peroxisome proliferator-activated receptor (Ppar) γ coactivator-1α (Pgc-1α) and uncoupling protein 1 (Ucp1). Capsaicin has been suggested to induce the activation of brown adipocytes, which is mediated by the stimulation of sympathetic nerves. However, capsaicin may directly affect the differentiation of brown preadipocytes, brown adipocyte function, or both, through its significant absorption. We herein demonstrated that Trpv1, a capsaicin receptor, is expressed in brown adipose tissue, and that its expression level is increased during the differentiation of HB2 brown preadipocytes. Furthermore, capsaicin induced calcium influx in brown preadipocytes. A treatment with capsaicin in the early stage of brown adipogenesis did not affect lipid accumulation or the expression levels of Fabp4 (a gene expressed in mature adipocytes), Pparγ2 (a master regulator of adipogenesis) or brown adipocyte-selective genes. In contrast, a treatment with capsaicin in the late stage of brown adipogenesis slightly increased the expression levels of Fabp4, Pparγ2 and Pgc-1α. Although capsaicin did not affect the basal expression level of Ucp1, Ucp1 induction by forskolin was partially inhibited by capsaicin, irrespective of the dose of capsaicin. The results of the present study suggest the direct effects of capsaicin on brown adipocytes or in the late stage of brown adipogenesis. PMID:26781688

  12. N-acetyl cysteine reduces oxidative toxicity, apoptosis, and calcium entry through TRPV1 channels in the neutrophils of patients with polycystic ovary syndrome.

    PubMed

    Köse, S A; Nazıroğlu, M

    2015-03-01

    Polycystic ovary syndrome (PCOS) is a common inflammatory and oxidant disease with an uncertain pathogenesis. N-acetyl cysteine (NAC) decreases oxidative stress, intracellular free calcium ion [Ca(2+)]i, and apoptosis levels in human neutrophil. We aimed to investigate the effects of NAC on apoptosis, oxidative stress, and Ca(2+) entry through transient receptor potential vanilloid 1 (TRPV1) and TRP melastatin 2 (TRPM2) channels in neutrophils from patients with PCOS. Neutrophils isolated from PCOS group were investigated in three settings: (1) after incubation with TRPV1 channel blocker capsazepine or TRPM2 channel blocker 2-aminoethyl diphenylborinate (2-APB), (2) after supplementation with NAC (for 6 weeks), and (3) with combination (capsazepine + 2-APB + NAC) exposure. The neutrophils in TRPM2 and TRPV1 experiments were stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 1 μM) and capsaicin (10 μM) as concentration agonists, respectively. Neutrophil lipid peroxidation and capsaicin-induced increase in [Ca(2+)]i concentrations were reduced by capsazepine and NAC treatments. However, the [Ca(2+)]i concentration did not change by fMLP stimulation. Neutrophil lipid peroxidation, apoptosis, caspase-3, caspase-9, cytosolic reactive oxygen species production, and mitochondrial membrane depolarization values were decreased by NAC treatment although neutrophil glutathione peroxidase and reduced glutathione levels were increased by the NAC treatment. Serum lipid peroxidation, luteinizing hormone, testosterone, insulin, interleukin-1 beta, and homocysteine levels were decreased by NAC treatment although serum vitamin A, beta-carotene, vitamin E, and total antioxidant status were increased by the NAC treatment. In conclusion, NAC reduced oxidative stress, apoptosis, cytokine levels, and Ca(2+) entry through TRPV1 channel, which provide supportive evidence that oxidative stress and TRPV1 channel plays a key role in etiology of PCOS. PMID:25666878

  13. Maresin 1 Inhibits TRPV1 in Temporomandibular Joint-Related Trigeminal Nociceptive Neurons and TMJ Inflammation-Induced Synaptic Plasticity in the Trigeminal Nucleus

    PubMed Central

    Park, Chul-Kyu

    2015-01-01

    In the trigeminal system, disruption of acute resolution processing may lead to uncontrolled inflammation and chronic pain associated with the temporomandibular joint (TMJ). Currently, there are no effective treatments for TMJ pain. Recently, it has been recognized that maresin 1, a newly identified macrophage-derived mediator of inflammation resolution, is a potent analgesic for somatic inflammatory pain without noticeable side effects in mice and a potent endogenous inhibitor of transient receptor potential vanilloid 1 (TRPV1) in the somatic system. However, the molecular mechanisms underlying the analgesic actions of maresin 1 on TMJ pain are unclear in the trigeminal system. Here, by performing TMJ injection of a retrograde labeling tracer DiI (a fluorescent dye), I showed that maresin 1 potently inhibits capsaicin-induced TRPV1 currents and neuronal activity via Gαi-coupled G-protein coupled receptors in DiI-labeled trigeminal nociceptive neurons. Further, maresin 1 blocked TRPV1 agonist-evoked increases in spontaneous excitatory postsynaptic current frequency and abolished TMJ inflammation-induced synaptic plasticity in the trigeminal nucleus. These results demonstrate the potent actions of maresin 1 in regulating TRPV1 in the trigeminal system. Thus, maresin 1 may serve as a novel endogenous inhibitor for treating TMJ-inflammatory pain in the orofacial region. PMID:26617436

  14. Pharmacology of modality-specific transient receptor potential vanilloid-1 antagonists that do not alter body temperature.

    PubMed

    Reilly, Regina M; McDonald, Heath A; Puttfarcken, Pamela S; Joshi, Shailen K; Lewis, LaGeisha; Pai, Madhavi; Franklin, Pamela H; Segreti, Jason A; Neelands, Torben R; Han, Ping; Chen, Jun; Mantyh, Patrick W; Ghilardi, Joseph R; Turner, Teresa M; Voight, Eric A; Daanen, Jerome F; Schmidt, Robert G; Gomtsyan, Arthur; Kort, Michael E; Faltynek, Connie R; Kym, Philip R

    2012-08-01

    The transient receptor potential vanilloid-1 (TRPV1) channel is involved in the development and maintenance of pain and participates in the regulation of temperature. The channel is activated by diverse agents, including capsaicin, noxious heat (≥ 43°C), acidic pH (< 6), and endogenous lipids including N-arachidonoyl dopamine (NADA). Antagonists that block all modes of TRPV1 activation elicit hyperthermia. To identify efficacious TRPV1 antagonists that do not affect temperature antagonists representing multiple TRPV1 pharmacophores were evaluated at recombinant rat and human TRPV1 channels with Ca(2+) flux assays, and two classes of antagonists were identified based on their differential ability to inhibit acid activation. Although both classes of antagonists completely blocked capsaicin- and NADA-induced activation of TRPV1, select compounds only partially inhibited activation of the channel by protons. Electrophysiology and calcitonin gene-related peptide release studies confirmed the differential pharmacology of these antagonists at native TRPV1 channels in the rat. Comparison of the in vitro pharmacological properties of these TRPV1 antagonists with their in vivo effects on core body temperature confirms and expands earlier observations that acid-sparing TRPV1 antagonists do not significantly increase core body temperature. Although both classes of compounds elicit equivalent analgesia in a rat model of knee joint pain, the acid-sparing antagonist tested is not effective in a mouse model of bone cancer pain. PMID:22570364

  15. Biological Activities of Red Pepper (Capsicum annuum) and Its Pungent Principle Capsaicin: A Review.

    PubMed

    Srinivasan, Krishnapura

    2016-07-01

    Capsaicin, the pungent alkaloid of red pepper (Capsicum annuum) has been extensively studied for its biological effects which are of pharmacological relevance. These include: cardio protective influence, antilithogenic effect, antiinflammatory, and analgesia, thermogenic influence, and beneficial effects on gastrointestinal system. Therefore, capsaicinoids may have the potential clinical value for pain relief, cancer prevention and weight loss. It has been shown that capsaicinoids are potential agonists of capsaicin receptor (TRPV1). They could exert the effects not only through the receptor-dependent pathway but also through the receptor-independent one. The involvement of neuropeptide Substance P, serotonin, and somatostatin in the pharmacological actions of capsaicin has been extensively investigated. Topical application of capsaicin is proved to alleviate pain in arthritis, postoperative neuralgia, diabetic neuropathy, psoriasis, etc. Toxicological studies on capsaicin administered by different routes are documented. Capsaicin inhibits acid secretion, stimulates alkali and mucus secretion and particularly gastric mucosal blood flow which helps in prevention and healing of gastric ulcers. Antioxidant and antiinflammatory properties of capsaicin are established in a number of studies. Chemopreventive potential of capsaicin is evidenced in cell line studies. The health beneficial hypocholesterolemic influence of capsaicin besides being cardio protective has other implications, viz., prevention of cholesterol gallstones and protection of the structural integrity of erythrocytes under conditions of hypercholesterolemia. Beneficial influences of capsaicin on gastrointestinal system include digestive stimulant action and modulation of intestinal ultrastructure so as to enhance permeability to micronutrients. PMID:25675368

  16. [Capsaicin in treatment of neuropathic pain].

    PubMed

    Kamchatnov, P R; Evzelman, M A; Abusueva, B A; Volkov, A I

    2014-01-01

    Treatment of neuropathic pain (NP) is a serious medical problem. Antiepileptic drugs and antidepressants, used to relief pain, act on the central pain mechanisms and cause several side-effects, thus substantially restricting possibilities of their clinical application.At the same time, NP often has a peripheral component. Ligand-associated channels, including vanilloid receptors TRPV1, play a key role in the development of regional NP syndromes. Capsaicin, a component of chili pepper and several other plants, is a highly selective ligand of TRPV1 receptors and has long been used in treatment of pain syndromes. However, its using is limited by short-term action and relatively low efficacy. Recently it has been shown that the local use of single high doses of capsaicin during 30-60 min causes a marked stable(> 12 weeks) effect. The decrease in NP (>50%) is seen in about half of patients. Current studies will allow to single out groups of patients with the maximal treatment effect of capsaicin. PMID:25629137

  17. Electroacupuncture at ST25 inhibits jejunal motility: Role of sympathetic pathways and TRPV1

    PubMed Central

    Yu, Zhi; Zhang, Na; Lu, Chun-Xia; Pang, Ting-Ting; Wang, Kai-Yue; Jiang, Jing-Feng; Zhu, Bing; Xu, Bin

    2016-01-01

    AIM: To investigate whether electroacupuncture (EA) at ST25 affects jejunal motility in vivo and if so, whether a sympathetic pathway is involved. METHODS: Jejunal motility was assessed using a manometric balloon placed in the jejunum approximately about 3-5 cm away from the suspensory ligament of the duodenum in anesthetized animals. The effects of EA at ST25 were measured in male Sprague-Dawley rats, some of which were treated with propranolol or clenbuterol (EA intensities: 1, 3, 5, 7, and 9 mA), and in male transient receptor potential vanilloid-1 (TRPV1) (capsaicin receptor) knockout mice (EA intensities: 1, 2, and 4 mA). RESULTS: Anesthetized rats exhibited three types of fasting jejunal motor patterns (types A, B, and C), and only type C rats responded to EA stimulation. In type C rats, EA at ST25 significantly suppressed the motor activity of the jejunum in an intensity-dependent manner. The inhibitory effect of EA was weakened by propranolol (β adrenoceptor antagonist) and disappeared with clenbuterol (β adrenoceptor agonist) induced inhibition of motility, suggesting that the effect of EA on motility is mediated via a sympathetic pathway. Compared with wild-type mice, EA at ST25 was less effective in TRPV1 knockout mice, suggesting that this multi-modal sensor channel participates in the mechanism. CONCLUSION: EA at ST25 was found to inhibit jejunal motility in an intensity-dependent manner, via a mechanism in which sympathetic nerves and TRPV1 receptors play an important role. PMID:26855542

  18. Structure-Driven Pharmacology of Transient Receptor Potential Channel Vanilloid 1.

    PubMed

    Díaz-Franulic, Ignacio; Caceres-Molina, Javier; Sepulveda, Romina V; Gonzalez-Nilo, Fernando; Latorre, Ramon

    2016-09-01

    The transient receptor potential vanilloid 1 (TRPV1) ion channel is a polymodal receptor that mediates the flux of cations across the membrane in response to several stimuli, including heat, voltage, and ligands. The best known agonist of TRPV1 channels is capsaicin, the pungent component of "hot" chili peppers. In addition, peptides found in the venom of poisonous animals, along with the lipids phosphatidylinositol 4,5-biphosphate, lysophosphatidic acid, and cholesterol, bind to TRPV1 with high affinity to modulate channel gating. Here, we discuss the functional evidence regarding ligand-dependent activation of TRPV1 channels in light of structural data recently obtained by cryoelectron microscopy. This review focuses on the mechanistic insights into ligand binding and allosteric gating of TRPV1 channels and the relevance of accurate polymodal receptor biophysical characterization for drug design in novel pain therapies. PMID:27335334

  19. Loss of capsaicin-induced meningeal neurogenic sensory vasodilatation in diabetic rats.

    PubMed

    Dux, M; Rosta, J; Pintér, S; Sántha, P; Jancsó, G

    2007-11-30

    Neuropathic alterations of sensory nerves involved in the mediation of neurogenic inflammation of the meninges may contribute to the increased incidence of headaches in diabetics. In the rat, activation of capsaicin-sensitive nociceptors, which express the transient receptor potential vanilloid type 1 (TRPV1) receptor, induces meningeal vasodilatation, a significant component of neurogenic inflammation, through the release of calcitonin gene-related peptide (CGRP). This study examines the effects of streptozotocin-induced diabetes on TRPV1 receptor-mediated neurogenic sensory vasodilatation, CGRP release and nerve fiber density in the rat dura mater. In a cranial window preparation, epidural application of capsaicin (10(-7) M) produced distinct vasodilatory responses in control animals as measured by laser Doppler flowmetry. In diabetic rats, capsaicin-induced vasodilatation was reduced or even abolished 6, but not 2 or 4 weeks after diabetes induction. In contrast, vasoconstriction, a non-neurogenic response to capsaicin at a higher concentration (10(-5) M), was not altered in diabetic rats. The vasodilatory effects of histamine (10(-5) M), acetylcholine (10(-4) M) and CGRP (10(-5) M) were similar in control, diabetic and insulin-treated diabetic animals. In diabetic rats, a significant decrease in the capsaicin-evoked release of CGRP and reduction in the density of TRPV1-immunoreactive (IR) nerves were demonstrated. Treatment of the diabetic rats with insulin restored both the vasodilatory response and the capsaicin-induced CGRP release toward control values. In conclusion, this study revealed a marked impairment of meningeal TRPV1-IR nerves in streptozotocin diabetic rats by showing reduced neurogenic sensory vasodilatation, decreased capsaicin-evoked CGRP release and reduction in the number of TRPV1-IR nerve fibers of the dura mater. The findings suggest that capsaicin-sensitive afferents may play an important role in meningeal nociceptor function and their

  20. ARA 290 relieves pathophysiological pain by targeting TRPV1 channel: Integration between immune system and nociception.

    PubMed

    Zhang, Wenjia; Yu, Guanling; Zhang, Mengyuan

    2016-02-01

    ARA 290 is an erythropoietin-derived polypeptide that possesses analgesic and tissue protective effect in many diseases such as diabetes and cancer. The analgesic effect of ARA 290 is mediated by its anti-inflammatory and immunomodulatory functions, or more specifically, by targeting the innate repair receptor (IRR) to down-regulate inflammation to alleviate neuropathic pain. However, whether other mechanisms or pathways are involved in ARA 290-mediated analgesic effect remains elusive. In this study, we are particularly interested in whether ARA 290 could directly target peripheral nociceptors by blocking or influencing receptors in pain sensation. Using calcium imaging, cell culture and behavioral tests, we demonstrated that ARA 290 was able to specifically inhibit TRPV1 channel activity, and relieve the mechanical hypersensitivity induced by capsaicin. Our study suggested that ARA 290 could potentially function as a novel antagonist for TRPV1 channel. This finding would not only contribute to the development of new pain treatment using ARA 290, but also help to improve our understanding of the integration between the immune system and the peripheral nervous system. PMID:26774587

  1. Bradykinin Induces TRPV1 Exocytotic Recruitment in Peptidergic Nociceptors

    PubMed Central

    Mathivanan, Sakthikumar; Devesa, Isabel; Changeux, Jean-Pierre; Ferrer-Montiel, Antonio

    2016-01-01

    Transient receptor potential vanilloid I (TRPV1) sensitization in peripheral nociceptors is a prominent phenomenon that occurs in inflammatory pain conditions. Pro-algesic agents can potentiate TRPV1 activity in nociceptors through both stimulation of its channel gating and mobilization of channels to the neuronal surface in a context dependent manner. A recent study reported that ATP-induced TRPV1 sensitization in peptidergic nociceptors involves the exocytotic release of channels trafficked by large dense core vesicles (LDCVs) that cargo alpha-calcitonin gene related peptide alpha (αCGRP). We hypothesized that, similar to ATP, bradykinin may also use different mechanisms to sensitize TRPV1 channels in peptidergic and non-peptidergic nociceptors. We found that bradykinin notably enhances the excitability of peptidergic nociceptors, and sensitizes TRPV1, primarily through the bradykinin receptor 2 pathway. Notably, bradykinin sensitization of TRPV1 in peptidergic nociceptors was significantly blocked by inhibiting Ca2+-dependent neuronal exocytosis. In addition, silencing αCGRP gene expression, but not substance P, drastically reduced bradykinin-induced TRPV1 sensitization in peptidergic nociceptors. Taken together, these findings indicate that bradykinin-induced sensitization of TRPV1 in peptidergic nociceptors is partially mediated by the exocytotic mobilization of new channels trafficked by αCGRP-loaded LDCVs to the neuronal membrane. Our findings further imply a central role of αCGRP peptidergic nociceptors in peripheral algesic sensitization, and substantiate that inhibition of LDCVs exocytosis is a valuable therapeutic strategy to treat pain, as it concurrently reduces the release of pro-inflammatory peptides and the membrane recruitment of thermoTRP channels. PMID:27445816

  2. Wu-Tou Decoction Inhibits Chronic Inflammatory Pain in Mice: Participation of TRPV1 and TRPA1 Ion Channels

    PubMed Central

    Wang, Chao; Liu, Chunfang; Wan, Hongye; Sun, Danni; Xu, Tengfei; Yang, Yue; Qu, Yakun; Xu, Ying; Jing, Xianghong; Liu, Junling; Chen, Shuping; Liu, Zhiqiang

    2015-01-01

    Wu-tou decoction (WTD) is a classic traditional Chinese medicine formula and has been used effectively to treat joint diseases clinically. Previous reports indicated that WTD possesses anti-inflammatory activity; however, its actions on pain have not been clarified. Here, we investigated the antinociceptive activity of WTD in CFA-induced mice, and its possible mechanism of the action associated with transient receptor potential (TRP) ion channels was also explored. Our results showed that 1.58, 3.15, and 6.30 g/kg WTD significantly attenuated mechanical, cold, and heat hypersensitivities. Moreover, WTD effectively inhibited spontaneous nociceptive responses to intraplantar injections of capsaicin and cinnamaldehyde, respectively. WTD also effectively suppressed jumping and wet-dog-shake behaviors to intraperitoneal injection of icilin. Additionally, WTD significantly reduced protein expression of TRPV1 and TRPA1 in dorsal root ganglia and skins of injured paw. Collectively, our data demonstrate firstly that WTD exerts antinociceptive activity in inflammatory conditions by attenuating mechanical, cold, and heat hypersensitivities. This antinociceptive effect may result in part from inhibiting the activities of TRPV1, TRPA1, and TRPM8, and the suppression of TRPV1 and TRPA1 protein by WTD was also highly effective. These findings suggest that WTD might be an attractive and suitable therapeutic agent for the management of chronic inflammatory pain. PMID:25839032

  3. TRPV1 Channels and Gastric Vagal Afferent Signalling in Lean and High Fat Diet Induced Obese Mice

    PubMed Central

    Kentish, Stephen J.; Frisby, Claudine L.; Kritas, Stamatiki; Li, Hui; Hatzinikolas, George; O’Donnell, Tracey A.; Wittert, Gary A.; Page, Amanda J.

    2015-01-01

    Aim Within the gastrointestinal tract vagal afferents play a role in control of food intake and satiety signalling. Activation of mechanosensitive gastric vagal afferents induces satiety. However, gastric vagal afferent responses to mechanical stretch are reduced in high fat diet mice. Transient receptor potential vanilloid 1 channels (TRPV1) are expressed in vagal afferents and knockout of TRPV1 reduces gastro-oesophageal vagal afferent responses to stretch. We aimed to determine the role of TRPV1 on gastric vagal afferent mechanosensitivity and food intake in lean and HFD-induced obese mice. Methods TRPV1+/+ and -/- mice were fed either a standard laboratory diet or high fat diet for 20wks. Gastric emptying of a solid meal and gastric vagal afferent mechanosensitivity was determined. Results Gastric emptying was delayed in high fat diet mice but there was no difference between TRPV1+/+ and -/- mice on either diet. TRPV1 mRNA expression in whole nodose ganglia of TRPV1+/+ mice was similar in both dietary groups. The TRPV1 agonist N-oleoyldopamine potentiated the response of tension receptors in standard laboratory diet but not high fat diet mice. Food intake was greater in the standard laboratory diet TRPV1-/- compared to TRPV1+/+ mice. This was associated with reduced response of tension receptors to stretch in standard laboratory diet TRPV1-/- mice. Tension receptor responses to stretch were decreased in high fat diet compared to standard laboratory diet TRPV1+/+ mice; an effect not observed in TRPV1-/- mice. Disruption of TRPV1 had no effect on the response of mucosal receptors to mucosal stroking in mice on either diet. Conclusion TRPV1 channels selectively modulate gastric vagal afferent tension receptor mechanosensitivity and may mediate the reduction in gastric vagal afferent mechanosensitivity in high fat diet-induced obesity. PMID:26285043

  4. The ion channel TRPV1 regulates the activation and proinflammatory properties of CD4+ T cells

    PubMed Central

    Bertin, Samuel; Aoki-Nonaka, Yukari; de Jong, Petrus Rudolf; Stanwood, Shawna R.; Srikanth, Sonal; Lee, Jihyung; To, Keith; Abramson, Lior; Yu, Timothy; Han, Tiffany; Touma, Ranim; Li, Xiangli; González-Navajas, José M.; Herdman, Scott; Corr, Maripat; Fu, Guo; Dong, Hui; Gwack, Yousang; Franco, Alessandra; Jefferies, Wilfred A.; Raz, Eyal

    2016-01-01

    TRPV1 is a Ca2+-permeable channel mostly studied as a pain receptor in sensory neurons. However, its role in other cell types is poorly understood. Here, we demonstrate that TRPV1 is functionally expressed in CD4+ T cells where it acts as a non-store-operated Ca2+ channel and contributes to T cell receptor (TCR)-induced Ca2+ influx, TCR signaling and T cell activation. In models of T cell-mediated colitis, TRPV1 promotes colitogenic T cell responses and intestinal inflammation. Furthermore, genetic and pharmacological inhibition of TRPV1 in human CD4+ T cells recapitulates the phenotype of murine Trpv1−/− CD4+ T cells. These findings suggest that TRPV1 inhibition could represent a new therapeutic strategy to restrain proinflammatory T cell responses. PMID:25282159

  5. Chronic alteration in phosphatidylinositol 4,5-biphosphate levels regulates capsaicin and mustard oil responses.

    PubMed

    Patil, Mayur J; Belugin, Sergei; Akopian, Armen N

    2011-06-01

    There is an agreement that acute (in minutes) hydrolysis and accumulation of phosphatidylinositol 4,5-bisphosphate (PIP(2) ) modulate TRPV1 and TRPA1 activities. Because inflammation results in PIP(2) depletion, persisting for long periods (hours to days) in pain models and in the clinic, we examined whether chronic depletion and accumulation of PIP(2) affect capsaicin (CAP) and mustard oil (MO) responses. In addition, we wanted to evaluate whether the effects of PIP(2) depend on TRPV1 and TRPA1 coexpression and whether the PIP(2) actions vary in expression cells vs. sensory neurons. Chronic PIP(2) production was stimulated by overexpression of phosphatidylinositol-4-phosphate-5-kinase, and PIP(2) -specific phospholipid 5'-phosphatase was selected to reduce plasma membrane levels of PIP(2) . Our results demonstrate that CAP (100 nM) responses and receptor tachyphylaxis are not significantly influenced by chronic changes in PIP(2) levels in wild-type (WT) or TRPA1 null-mutant sensory neurons as well as CHO cells expressing TRPV1 alone or with TRPA1. However, low concentrations of CAP (20 nM) produced a higher response after PIP(2) depletion in cells containing TRPV1 alone but not TRPV1 together with TRPA1. MO (25 μM) responses were also not affected by PIP(2) in WT sensory neurons and cells coexpressing TRPA1 and TRPV1. In contrast, PIP(2) reduction leads to pronounced tachyphylaxis to MO in cells with both channels. Chronic effect of PIP(2) on TRPA1 activity depends on presence of the TRPV1 channel and cell type (CHO vs. sensory neurons). In summary, chronic alterations in PIP(2) levels regulate magnitude of CAP and MO responses as well as MO tachyphylaxis. This regulation depends on coexpression profile of TRPA1 and TRPV1 and cell type. PMID:21337373

  6. Role of Transient Receptor Potential Vanilloid 1 in Inflammation and Autoimmune Diseases

    PubMed Central

    Tsuji, Fumio; Aono, Hiroyuki

    2012-01-01

    Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, is a receptor activated by high temperatures and chemical agonists such as the vanilloids and protons. Because of these properties, TRPV1 has emerged as a polymodal nocisensor of nociceptive afferent neurons. TRPV1 is thought to be a central transducer of hyperalgesia and a prime target for controlling pain pharmacologically because it is a point where many proalgesic pathways converge and it is upregulated and sensitized by inflammation and injury. However, whether TRPV1 agonists promote or inhibit inflammation remains unclear. We recently demonstrated that SA13353 (1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea), a novel TRPV1 agonist, inhibits tumor necrosis factor-a production by the activation of capsaicin-sensitive afferent neurons and reduces the severity of symptoms in kidney injury, lung inflammation, arthritis, and encephalomyelitis. These results suggest that TRPV1 agonists may act as anti-inflammatories in certain inflammatory and autoimmune conditions in vivo. Given the potential deleterious effects of inhibiting the population of channels with a protective function, caution should be taken in the use of potent TRPV1 antagonists as a general strategy to treat inflammation. Further studies are required to clarify the role of TRPV1 and neuropeptides, which are released because of TRPV1 activation in inflammation and autoimmune diseases. PMID:24280677

  7. Synergic Effects of Doxorubicin and Melatonin on Apoptosis and Mitochondrial Oxidative Stress in MCF-7 Breast Cancer Cells: Involvement of TRPV1 Channels.

    PubMed

    Koşar, Pınar Aslan; Nazıroğlu, Mustafa; Övey, İshak Suat; Çiğ, Bilal

    2016-04-01

    Transient receptor transient receptor potential vanilloid 1 (TRPV1) is a Ca(2+)-permeable channel gated by oxidative stress and capsaicin (CAP) and modulated by melatonin (MEL) and capsazepine (CPZ). A combination of doxorubicin (DOX) and MEL may offer a potential therapy for breast cancer by exerting antitumor and anti-apoptotic effects and modulating Ca(2+) influx and TRPV1 activity. We aimed to investigate the effects of MEL and DOX on the oxidative toxicity of MCF-7 human breast cancer cells, in addition to the activity of the TRPV1 channel and apoptosis. The MCF-7 cells were divided into the following six treatment groups: control, incubated with MEL (0.3 mM), incubated with 0.5 μM DOX, incubated with 1 μM DOX, incubated with MEL + 0.5 μM DOX, or incubated with MEL + 1 μM DOX. The intracellular free Ca(2+) concentration was higher in the DOX groups than in the control, and the concentration was decreased by MEL. The intracellular free Ca(2+) concentration was further increased by treatment with the TRPV1 channel activator CAP (0.01 mM), and it was decreased by the CPZ (0.1 mM). The intracellular production of reactive oxygen species, mitochondrial membrane depolarization, apoptosis level, procaspase 9 and PARP activities, and caspase 3 and caspase 9 activities were higher in the DOX and MEL groups than in the control. Apoptosis and the activity of caspase 9 were further increased in the DOX plus MEL groups. Taken together, the findings indicate that MEL supported the effects of DOX by activation of TRPV1 and apoptosis, as well as by inducing MCF-7 cell death. As the apoptosis and caspase activity of cancer cells increase because of their elevated metabolism, MEL may be useful in supporting their apoptotic capacity. PMID:26525975

  8. Role of pre-junctional CB1, but not CB2 , TRPV1 or GPR55 receptors in anandamide-induced inhibition of the vasodepressor sensory CGRPergic outflow in pithed rats.

    PubMed

    Marichal-Cancino, Bruno A; Altamirano-Espinoza, Alain H; Manrique-Maldonado, Guadalupe; MaassenVanDenBrink, Antoinette; Villalón, Carlos M

    2014-03-01

    Stimulation of the perivascular sensory outflow in pithed rats produces vasodepressor responses mediated by CGRP release. Interestingly, endocannabinoids such as anandamide (which interacts with CB1 , CB2 , TRPV1 and GPR55 receptors) can regulate the activity of perivascular sensory nerves in dural blood vessels by modulating CGRP release. Yet, as no publication has reported whether this mechanism is operative in the healthy systemic vasculature, this study has specifically analysed the receptors mediating the potential inhibitory effects of the cannabinoid (CB) receptor agonists anandamide (non-selective), JWH-015 (CB2 ) and lysophosphatidylinositol (GPR55) on the rat vasodepressor sensory CGRPergic outflow (an index of systemic vasodilatation). Healthy pithed rats were pre-treated with consecutive i.v. continuous infusions of hexamethonium, methoxamine and the above agonists. Electrical spinal (T9 -T12 ) stimulation of the vasodepressor sensory CGRPergic outflow or i.v. injections of α-CGRP produced frequency-dependent or dose-dependent vasodepressor responses. The infusions of anandamide in a dose-dependent manner inhibited the vasodepressor responses by electrical stimulation (remaining unaffected by JWH-015 or lysophosphatidylinositol), but not those by α-CGRP. After i.v. administration of antagonists, the inhibition by 3.1 μg/kg min anandamide was: (i) potently blocked by 31-100 μg/kg NIDA41020 (CB1 ), (ii) unaffected by 180 μg/kg AM630 (CB2 ), 31 μg/kg cannabidiol (GPR55) or 31-100 μg/kg capsazepine (TRPV1) and (iii) slightly blocked by 310 μg/kg AM630. The above doses of antagonists were enough to block their respective receptors. These results suggest that anandamide-induced inhibition of the vasodepressor sensory CGRPergic outflow is mainly mediated by pre-junctional activation of CB1 receptors, with no pharmacological evidence for the role of CB2 , TRPV1 or GPR55 receptors. PMID:24118786

  9. Iron overload causes osteoporosis in thalassemia major patients through interaction with transient receptor potential vanilloid type 1 (TRPV1) channels

    PubMed Central

    Rossi, Francesca; Perrotta, Silverio; Bellini, Giulia; Luongo, Livio; Tortora, Chiara; Siniscalco, Dario; Francese, Matteo; Torella, Marco; Nobili, Bruno; Di Marzo, Vincenzo; Maione, Sabatino

    2014-01-01

    The pathogenesis of bone resorption in β-thalassemia major is multifactorial and our understanding of the underlying molecular and cellular mechanisms remains incomplete. Considering the emerging importance of the endocannabinoid/endovanilloid system in bone metabolism, it may be instructive to examine a potential role for this system in the development of osteoporosis in patients with β-thalassemia major and its relationship with iron overload and iron chelation therapy. This study demonstrates that, in thalassemic-derived osteoclasts, tartrate-resistant acid phosphatase expression inversely correlates with femoral and lumbar bone mineral density, and directly correlates with ferritin levels and liver iron concentration. The vanilloid agonist resiniferatoxin dramatically reduces cathepsin K levels and osteoclast numbers in vitro, without affecting tartrate-resistant acid phosphatase expression. The iron chelators deferoxamine, deferiprone and deferasirox decrease both tartrate-resistant acid phosphatase and cathepsin K expression, as well as osteoclast activity. Taken together, these data show that transient receptor potential vanilloid type 1 activation/desensitization influences tartrate-resistant acid phosphatase expression and activity, and this effect is dependent on iron, suggesting a pivotal role for iron overload in the dysregulation of bone metabolism in patients with thalassemia major. Our applied pharmacology provides evidence for the potential of iron chelators to abrogate these effects by reducing osteoclast activity. Whether iron chelation therapy is capable of restoring bone health in humans requires further study, but the potential to provide dual benefits for patients with β-thalassemia major –preventing iron-overload and alleviating associated osteoporotic changes – is exciting. PMID:25216685

  10. TRPV1: Turning up the heat on intestinal tumorigenesis

    PubMed Central

    de Jong, Petrus R; Bertin, Samuel; Raz, Eyal

    2015-01-01

    TRP channels are associated with the development and progression of cancer but their precise molecular roles in these processes are unclear. Recently, we showed that the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel is part of a negative feedback loop downstream of epidermal growth factor receptor signaling that suppresses intestinal tumorigenesis.

  11. Hypericum perforatum Attenuates Spinal Cord Injury-Induced Oxidative Stress and Apoptosis in the Dorsal Root Ganglion of Rats: Involvement of TRPM2 and TRPV1 Channels.

    PubMed

    Özdemir, Ümit Sinan; Nazıroğlu, Mustafa; Şenol, Nilgün; Ghazizadeh, Vahid

    2016-08-01

    Oxidative stress and cytosolic Ca(2+) overload have important roles on apoptosis in dorsal root ganglion (DRG) neurons after spinal cord injury (SCI). Hypericum perforatum (HP) has an antioxidant property in the DRGs due to its ability to modulate NADPH oxidase and protein kinase C pathways. We aimed to investigate the protective property of HP on oxidative stress, apoptosis, and Ca(2+) entry through transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) channels in SCI-induced DRG neurons of rats. Rats were divided into four groups as control, HP, SCI, and SCI + HP. The HP groups received 30 mg/kg HP for three concessive days after SCI induction. The SCI-induced TRPM2 and TRPV1 currents and cytosolic free Ca(2+) concentration were reduced by HP. The SCI-induced decrease in glutathione peroxidase and cell viability values were ameliorated by HP treatment, and the SCI-induced increase in apoptosis, caspase 3, caspase 9, cytosolic reactive oxygen species (ROS) production, and mitochondrial membrane depolarization values in DRG of SCI group were overcome by HP treatment. In conclusion, we observed a protective role of HP on SCI-induced oxidative stress, apoptosis, and Ca(2+) entry through TRPM2 and TRPV1 in the DRG neurons. Our findings may be relevant to the etiology and treatment of SCI by HP. Graphical Abstract Possible molecular pathways of involvement of Hypericum perforatum (HP) on apoptosis, oxidative stress, and calcium accumulation through TRPM2 and TRPV1 channels in DRG neurons of SCI-induced rats. The TRPM2 channel is activated by ADP-ribose and oxidative stress through activation of ADP-ribose pyrophosphate although it was inhibited by N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethyl diphenylborinate (2APB). The TRPV1 channel is activated by oxidative stress and capsaicin and it is blocked by capsazepine. Injury in the DRG can result in augmented ROS release, leading to Ca(2+) uptake through

  12. Blocking of TRPV-1 in the parodontium relieves orthodontic pain by inhibiting the expression of TRPV-1 in the trigeminal ganglion during experimental tooth movement in rats.

    PubMed

    Gao, Yunan; Liu, Yingfei; Zhu, Kun; Zhang, Zhichao; Qiao, Hu; Lu, Zhen; Zhong, Tianyu; Liu, Yong; Zhou, Hong

    2016-08-15

    Orthodontic pain has confused the orthodontics for a long time, and recent research demonstrated that transient receptor potential vanilloid type 1 (TRPV1) had crucial functions in transduction of painful stimuli. The present research investigated the analgesia effects of the blocking TRPV1 on orthodontic pain during experimental tooth movement. Under challenge with experimental tooth movement, the expression of TRPV1 in the parodontium was increased in a time-dependent and force-dependent manner. And treatment with selective TRPV1 antagonist AMG-9810 in the parodontium reduced the expression of TRPV1 in the trigeminal ganglion (TG) and decreased the secretion of IL-1β in the gingival crevicular fluid. Furthermore, AMG-9810 could relieve orthodontic pain arising from experimental tooth movement in rats. We suggest that TRPV1 both in the parodontium and trigeminal ganglion are involved in orthodontic pain, and TRPV1 in the parodontium influence on orthodontic pain through reducing the expression of TRPV1 in trigeminal ganglion. Our finding may help to develop strategies for relieving orthodontic pain after orthodontics. PMID:27267133

  13. ΔN-TRPV1: A Molecular Co-detector of Body Temperature and Osmotic Stress.

    PubMed

    Zaelzer, Cristian; Hua, Pierce; Prager-Khoutorsky, Masha; Ciura, Sorana; Voisin, Daniel L; Liedtke, Wolfgang; Bourque, Charles W

    2015-10-01

    Thirst and antidiuretic hormone secretion occur during hyperthermia or hypertonicity to preserve body hydration. These vital responses are triggered when hypothalamic osmoregulatory neurons become depolarized by ion channels encoded by an unknown product of the transient receptor potential vanilloid-1 gene (Trpv1). Here, we show that rodent osmoregulatory neurons express a transcript of Trpv1 that mediates the selective translation of a TRPV1 variant that lacks a significant portion of the channel's amino terminus (ΔN-TRPV1). The mRNA transcript encoding this variant (Trpv1dn) is widely expressed in the brains of osmoregulating vertebrates, including the human hypothalamus. Transfection of Trpv1dn into heterologous cells induced the expression of ion channels that could be activated by either hypertonicity or by heating in the physiological range. Moreover, expression of Trpv1dn rescued the osmosensory and thermosensory responses of single hypothalamic neurons obtained from Trpv1 knockout mice. ΔN-TRPV1 is therefore a co-detector of core body temperature and fluid tonicity. PMID:26387947

  14. Resolving TRPV1 and TNF-α Mediated Spinal Cord Synaptic Plasticity and Inflammatory Pain with Neuroprotectin D1

    PubMed Central

    Park, Chul-Kyu; Lü, Ning; Xu, Zhen-Zhong; Liu, Tong; Serhan, Charles N.; Ji, Ru-Rong

    2011-01-01

    Mechanisms of inflammatory pain are not fully understood. We investigated the role of TRPV1 and TNF-α, two critical mediators for inflammatory pain, in regulating spinal cord synaptic transmission. We found in mice lacking Trpv1 the frequency but not the amplitude of spontaneous EPSCs (sEPSCs) in lamina II neurons of spinal cord slices is reduced. Further, C-fiber-induced spinal long-term potentiation (LTP) in vivo is abolished in Trpv1 knockout mice. TNF-α also increases sEPSC frequency but not amplitude in spinal lamina IIo neurons, and this increase is abolished in Trpv1 knockout mice. Single-cell PCR analysis revealed that TNF-α-responding neurons in lamina IIo are exclusively excitatory (vGluT2+) neurons. Notably, neuroprotectin-1 (NPD1), an anti-inflammatory lipid mediator derived from omega-3 polyunsaturated fatty acid (docosahexaenoic acid) blocks TNF-α- and capsaicin-evoked sEPSC frequency increases but has no effect on basal synaptic transmission. Strikingly, NPD1 potently inhibits capsaicin-induced TRPV1 current (IC50=0.4 nM) in dissociated dorsal root ganglion neurons, and this IC50 is ≈ 500 times lower than that of AMG9810, a commonly used TRPV1 antagonist. NPD1 inhibition of TRPV1 is mediated by GPCRs, since the effects were blocked by pertussis toxin. In contrast, NPD1 had not effect on mustard oil-induced TRPA1 currents. Spinal injection of NPD1, at very low doses (0.1–10 ng), blocks spinal LTP and reduces TRPV1-dependent inflammatory pain, without affecting baseline pain. NPD1 also reduces TRPV1-independent but TNF-α-dependent pain hypersensitivity. Our findings demonstrate a novel role of NPD1 in regulating TRPV1/TNF-α-mediated spinal synaptic plasticity and identify NPD1 as a novel analgesic for treating inflammatory pain. PMID:22016541

  15. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch

    PubMed Central

    Anand, P.; Bley, K.

    2011-01-01

    Summary Topical capsaicin formulations are used for pain management. Safety and modest efficacy of low-concentration capsaicin formulations, which require repeated daily self-administration, are supported by meta-analyses of numerous studies. A high-concentration capsaicin 8% patch (Qutenza™) was recently approved in the EU and USA. A single 60-min application in patients with neuropathic pain produced effective pain relief for up to 12 weeks. Advantages of the high-concentration capsaicin patch include longer duration of effect, patient compliance, and low risk for systemic effects or drug–drug interactions. The mechanism of action of topical capsaicin has been ascribed to depletion of substance P. However, experimental and clinical studies show that depletion of substance P from nociceptors is only a correlate of capsaicin treatment and has little, if any, causative role in pain relief. Rather, topical capsaicin acts in the skin to attenuate cutaneous hypersensitivity and reduce pain by a process best described as ‘defunctionalization’ of nociceptor fibres. Defunctionalization is due to a number of effects that include temporary loss of membrane potential, inability to transport neurotrophic factors leading to altered phenotype, and reversible retraction of epidermal and dermal nerve fibre terminals. Peripheral neuropathic hypersensitivity is mediated by diverse mechanisms, including altered expression of the capsaicin receptor TRPV1 or other key ion channels in affected or intact adjacent peripheral nociceptive nerve fibres, aberrant re-innervation, and collateral sprouting, all of which are defunctionalized by topical capsaicin. Evidence suggests that the utility of topical capsaicin may extend beyond painful peripheral neuropathies. PMID:21852280

  16. Optical stimulation in mice lacking the TRPV1 channel

    NASA Astrophysics Data System (ADS)

    Suh, Eul; Izzo Matic, Agnella; Otting, Margarete; Walsh, Joseph T., Jr.; Richter, Claus-Peter

    2009-02-01

    Lasers can be used to stimulate neural tissue, including the sciatic nerve or auditory neurons. Wells and coworkers suggested that neural tissue is likely stimulated by heat.[1,2] Ion channels that can be activated by heat are the TRPV channels, a subfamily of the Transient Receptor Potential (TRP) ion channels. TRPV channels are nonselective cation channels found in sensory neurons involved in nociception. In addition to various chemicals, TRPV channels can also be thermally stimulated. The activation temperature for the different TRPV channels varies and is 43°C for TRPV1 and 39°C for TRPV3. By performing an immunohistochemical staining procedure on frozen 20 μm cochlear slices using a primary TRPV1 antibody, we observed specific immunostaining of the spiral ganglion cells. Here we show that in mice that lack the gene for the TRPV1 channel optical radiation cannot evoke action potentials on the auditory nerve.

  17. A synergistic effect of simultaneous TRPA1 and TRPV1 activations on vagal pulmonary C-fiber afferents

    PubMed Central

    Lin, Yu-Jung; Lin, Ruei-Lung; Ruan, Ting; Khosravi, Mehdi

    2014-01-01

    Transient receptor potential ankyrin type 1 (TRPA1) and vanilloid type 1 (TRPV1) receptors are coexpressed in vagal pulmonary C-fiber sensory nerves. Because both these receptors are sensitive to a number of endogenous inflammatory mediators, it is conceivable that they can be activated simultaneously during airway inflammation. This study aimed to determine whether there is an interaction between these two polymodal transducers upon simultaneous activation, and how it modulates the activity of vagal pulmonary C-fiber sensory nerves. In anesthetized, spontaneously breathing rats, the reflex-mediated apneic response to intravenous injection of a combined dose of allyl isothiocyanate (AITC, a TRPA1 activator) and capsaicin (Cap, a TRPV1 activator) was ∼202% greater than the mathematical sum of the responses to AITC and Cap when they were administered individually. Similar results were also observed in anesthetized mice. In addition, the synergistic effect was clearly demonstrated when the afferent activity of single vagal pulmonary C-fiber afferents were recorded in anesthetized, artificially ventilated rats; C-fiber responses to AITC, Cap and AITC + Cap (in combination) were 0.6 ± 0.1, 0.8 ± 0.1, and 4.8 ± 0.6 impulses/s (n = 24), respectively. This synergism was absent when either AITC or Cap was replaced by other chemical activators of pulmonary C-fiber afferents. The pronounced potentiating effect was further demonstrated in isolated vagal pulmonary sensory neurons using the Ca2+ imaging technique. In summary, this study showed a distinct positive interaction between TRPA1 and TRPV1 when they were activated simultaneously in pulmonary C-fiber sensory nerves. PMID:25414245

  18. Structural insight into tetrameric hTRPV1 from homology modeling, molecular docking, molecular dynamics simulation, virtual screening, and bioassay validations.

    PubMed

    Feng, Zhiwei; Pearce, Larry V; Xu, Xiaomeng; Yang, Xiaole; Yang, Peng; Blumberg, Peter M; Xie, Xiang-Qun

    2015-03-23

    The transient receptor potential vanilloid type 1 (TRPV1) is a heat-activated cation channel protein, which contributes to inflammation, acute and persistent pain. Antagonists of human TRPV1 (hTRPV1) represent a novel therapeutic approach for the treatment of pain. Developing various antagonists of hTRPV1, however, has been hindered by the unavailability of a 3D structure of hTRPV1. Recently, the 3D structures of rat TRPV1 (rTRPV1) in the presence and absence of ligand have been reported as determined by cryo-EM. rTRPV1 shares 85.7% sequence identity with hTRPV1. In the present work, we constructed and reported the 3D homology tetramer model of hTRPV1 based on the cryo-EM structures of rTRPV1. Molecular dynamics (MD) simulations, energy minimizations, and prescreen were applied to select and validate the best model of hTRPV1. The predicted binding pocket of hTRPV1 consists of two adjacent monomers subunits, which were congruent with the experimental rTRPV1 data and the cyro-EM structures of rTRPV1. The detailed interactions between hTRPV1 and its antagonists or agonists were characterized by molecular docking, which helped us to identify the important residues. Conformational changes of hTRPV1 upon antagonist/agonist binding were also explored by MD simulation. The different movements of compounds led to the different conformational changes of monomers in hTRPV1, indicating that TRPV1 works in a concerted way, resembling some other channel proteins such as aquaporins. We observed that the selective filter was open when hTRPV1 bound with an agonist during MD simulation. For the lower gate of hTRPV1, we observed large similarities between hTRPV1 bound with antagonist and with agonist. A five-point pharmacophore model based on several antagonists was established, and the structural model was used to screen in silico for new antagonists for hTRPV1. By using the 3D TRPV1 structural model above, the pilot in silico screening has begun to yield promising hits with

  19. LPS from Porphyromonas gingivalis Sensitizes Capsaicin-Sensitive Nociceptors

    PubMed Central

    Ferraz, Caio Cezar Randi; Diógenes, Aníbal; Henry, Michael A.; Hargreaves, Kenneth M.

    2010-01-01

    Although odontogenic infections are often accompanied by pain, little is known about the potential mechanisms mediating this effect. In this study, we tested the hypothesis that trigeminal nociceptive neurons are directly sensitized by lipopolysaccharide (LPS) isolated from an endodontic pathogen, Porphyromonas gingivalis (P. gingivalis). In vitro studies conducted with cultures of rat trigeminal neurons demonstrated that pretreatment with LPS produced a significant increase in the capsaicin-evoked release of calcitonin gene-related peptide (CGRP) when compared to vehicle pretreatment, thus showing sensitization of the capsaicin receptor, TRPV1, by LPS. Furthermore, confocal microscopic examination of human tooth pulp samples showed the colocalization of the LPS receptor (toll-like receptor 4; TLR4) with CGRP containing nerve fibers. Collectively, these results suggest the direct sensitization of nociceptors by LPS at concentrations found in infected canal systems as one mechanism responsible for the pain associated with bacterial infections. PMID:21146075

  20. Moderate extracellular acidification inhibits capsaicin-induced cell death through regulating calcium mobilization, NF-{kappa}B translocation and ROS production in synoviocytes

    SciTech Connect

    Hu, Fen; Yang, Shuang; Zhao, Dan; Zhu, Shuyan; Wang, Yuxiang; Li, Junying

    2012-07-20

    Highlights: Black-Right-Pointing-Pointer Moderate extracellular acidification regulates intracellular Ca{sup 2+} mobilization. Black-Right-Pointing-Pointer Moderate acidification activates NF-{kappa}B nuclear translocation in synoviocytes. Black-Right-Pointing-Pointer Moderate acidification depresses the ROS production induced by capsaicin. Black-Right-Pointing-Pointer Moderate acidification inhibits capsaicin-caused synoviocyte death. -- Abstract: We previously show the expression of transient receptor potential vanilloid 1 (TRPV1) in primary synoviocytes from collagen-induced arthritis (CIA) rats. Capsaicin and lowered extracellular pH from 7.4 to 5.5 induce cell death through TRPV1-mediated Ca{sup 2+} entry and reactive oxygen species (ROS) production. However, under the pathological condition in rheumatoid arthritis, the synovial fluid is acidified to a moderate level (about pH 6.8). In the present study, we examined the effects of pH 6.8 on the TRPV1-mediated cell death. Our finding is different or even opposite from what was observed at pH 5.5. We found that the moderate extracellular acidification (from pH 7.4 to 6.8) inhibited the capsaicin-induced Ca{sup 2+} entry through attenuating the activity of TRPV1. In the mean time, it triggered a phospholipse C (PLC)-related Ca{sup 2+} release from intracellular stores. The nuclear translocation of NF-{kappa}B was found at pH 6.8, and this also depends on PLC activation. Moreover, the capsaicin-evoked massive ROS production and cell death were depressed at pH 6.8, both of which are dependent on the activation of PLC and NF-{kappa}B. Taken together, these results suggested that the moderate extracellular acidification inhibited the capsaicin-induced synoviocyte death through regulating Ca{sup 2+} mobilization, activating NF-{kappa}B nuclear translocation and depressing ROS production.

  1. TRPV1: ON THE ROAD TO PAIN RELIEF

    PubMed Central

    Jara-Oseguera, Andrés; Simon, Sidney A.

    2009-01-01

    Historically, drug research targeted to pain treatment has focused on trying to prevent the propagation of action potentials in the periphery from reaching the brain rather than pinpointing the molecular basis underlying the initial detection of the nociceptive stimulus: the receptor itself. This has now changed, given that many receptors of nociceptive stimuli have been identified and/or cloned. Transient Receptor Potential (TRP) channels have been implicated in several physiological processes such as mechanical, chemical and thermal stimuli detection. Ten years after the cloning of TRPV1, compelling data has been gathered on the role of this channel in inflammatory and neuropathic states. TRPV1 activation in nociceptive neurons, where it is normally expressed, triggers the release of neuropeptides and transmitters resulting in the generation of action potentials that will be sent to higher CNS areas where they will often be perceived as pain. Its activation also will evoke the peripheral release of pro-inflammatory compounds that may sensitize other neurons to physical, thermal or chemical stimuli. For these reasons as well as because its continuous activation causes analgesia, TRPV1 has become a viable drug target for clinical use in the management of pain. This review will provide a general picture of the physiological and pathophysiological roles of the TRPV1 channel and of its structural, pharmacological and biophysical properties. Finally, it will provide the reader with an overall view of the status of the discovery of potential therapeutic agents for the management of chronic and neuropathic pain. PMID:20021438

  2. TRPV1 gene deletion exacerbates inflammation and atypical cardiac remodeling after myocardial infarction

    PubMed Central

    Huang, Wei; Rubinstein, Jack; Prieto, Alejandro R.; Thang, Loc Vinh; Wang, Donna H.

    2009-01-01

    The transient receptor potential vanilloid (TRPV1) channels expressed in sensory afferent fibers innervating the heart may be activated by proton or endovanilloids released during myocardial ischemia (MI), leading to angina. Although our previous in vitro data indicate that TRPV1 activation may preserve cardiac function after ischemia-reperfusion (I/R) injury, the underlying mechanisms are largely unknown. To test the hypothesis that TRPV1 modulates inflammatory and early remodeling processes to prevent cardiac functional deterioration after myocardial infarction, TRPV1-null mutant (TRPV1-/-) and wild-type (WT) mice were subjected to left anterior descending coronary ligation or sham operation. The infarct size was greater in TRPV1-/- than in WT mice (P < 0.001) 3 days after MI, and the mortality rate was higher in TRPV1-/- than in WT mice (P < 0.05) 7 days after MI. The levels of plasma cardiac troponin I; cytokines including TNF-α, IL-1β, and IL-6; chemokines including MCP-1 and MIP-2; infiltration of inflammatory cells including neutrophil, macrophage, and myofibroblast; as well as collagen contents were greater in TRPV1-/- than in WT mice (P < 0.05) in the infarct area on day 3 and 7 after MI. Changes in left ventricular (LV) geometry led to increased end-systolic and -diastolic diameters and reduced contractile function in TRPV1-/- compared to WT mice. These data show that TRPV1 gene deletion results in excessive inflammation, disproportional LV remodeling, and deteriorated cardiac function after MI, indicating that TRPV1 may prevent infarct expansion and cardiac injury by inhibiting inflammation and abnormal tissue remodeling. PMID:19114647

  3. TRPV1 regulates activation and modulation of TRPA1 by Ca2+

    PubMed Central

    Patil, Mayur J.; Jeske, Nathaniel A.; Akopian, Armen N.

    2010-01-01

    The transient receptor potential A1 (TRPA1) channel contributes to nociceptive signaling in certain pain models. It has been suggested that Ca2+, which activates and modulates TRPA1, could play a critical regulatory role in this process. Since TRPA1 and TRPV1 channels are co-expressed and interact in neurons, we investigated whether activation and modulation of TRPA1 by Ca2+ is regulated by TRPV1. Cell-attached recordings showed that TRPA1 is activated by extracellular Ca2+ ([Ca2+]e) in concentration-response fashion. This activation, especially by 2mM [Ca2+]e was substantially suppressed by co-expression with TRPV1. Inside-out recordings demonstrated that intracellular Ca2+ ([Ca2+]i)-triggered activation of TRPA1 was attenuated by the presence of TRPV1 only at 2 mM [Ca2+]e, but not in Ca2+-free conditions. Further, depletion of internal Ca2+ stores by thapsigargin generated TRPA1-mediated currents, which is affected by TRPV1 in both Chinee hamster ovary cells and sensory neurons. Since mustard oil current (IMO) is modulated by [Ca2+]e, we next examined whether alterations in the Ca2+-permeability of TRPV1 by mutating Y671 effect IMO properties. First it was demonstrated that the mutations in TRPV1 did not affect association of the TRPA1 and TRPV1 channels. However, these TRPV1 mutations, particularly Y671K, altered the following characteristics of TRPA1: magnitude of IMO in presence and absence of [Ca2+]e; the influence of [Ca2+]e on the voltage-dependency of IMO, and open probability of single-channel IMO. In summary, activation of TRPA1 by [Ca2+]e and [Ca2+]i is controlled by the TRPV1 channel, and characteristics of IMO depend on Ca2+ permeability of the TRPV1 channel. PMID:20884333

  4. Pharmacological characterisation of capsaicin-induced relaxations in human and porcine isolated arteries

    PubMed Central

    Gupta, Saurabh; Lozano-Cuenca, Jair; Villalón, Carlos M.; de Vries, René; Garrelds, Ingrid M.; Avezaat, Cees J. J.; van Kats, Jorge P.; Saxena, Pramod R.

    2007-01-01

    Capsaicin, a pungent constituent from red chilli peppers, activates sensory nerve fibres via transient receptor potential vanilloid receptors type 1 (TRPV1) to release neuropeptides like calcitonin gene-related peptide (CGRP) and substance P. Capsaicin-sensitive nerves are widely distributed in human and porcine vasculature. In this study, we examined the mechanism of capsaicin-induced relaxations, with special emphasis on the role of CGRP, using various pharmacological tools. Segments of human and porcine proximal and distal coronary arteries, as well as cranial arteries, were mounted in organ baths. Concentration response curves to capsaicin were constructed in the absence or presence of the CGRP receptor antagonist olcegepant (BIBN4096BS, 1 μM), the neurokinin NK1 receptor antagonist L-733060 (0.5 μM), the voltage-sensitive calcium channel blocker ruthenium red (100 μM), the TRPV1 receptor antagonist capsazepine (5 μM), the nitric oxide synthetase inhibitor Nω-nitro-l-arginine methyl ester HCl (l-NAME; 100 μM), the gap junction blocker 18α-glycyrrhetinic acid (10 μM), as well as the RhoA kinase inhibitor Y-27632 (1 μM). Further, we also used the K+ channel inhibitors 4-aminopyridine (1 mM), charybdotoxin (0.5 μM) + apamin (0.1 μM) and iberiotoxin (0.5 μM) + apamin (0.1 μM). The role of the endothelium was assessed by endothelial denudation in distal coronary artery segments. In distal coronary artery segments, we also measured levels of cyclic adenosine monophosphate (cAMP) after exposure to capsaicin, and in human segments, we also assessed the amount of CGRP released in the organ bath fluid after exposure to capsaicin. Capsaicin evoked concentration-dependent relaxant responses in precontracted arteries, but none of the above-mentioned inhibitors did affect these relaxations. There was no increase in the cAMP levels after exposure to capsaicin, unlike after (exogenously administered) α-CGRP. Interestingly, there were

  5. Mapping the Binding Site of TRPV1 on AKAP79: Implications for Inflammatory Hyperalgesia

    PubMed Central

    Stott, Katherine; McNaughton, Peter A.

    2014-01-01

    Inflammation causes hyperalgesia, an enhanced sensitivity to noxious stimuli. Transient receptor potential vanilloid 1 (TRPV1), a thermo-TRP ion channel activated by painful levels of heat, is an important contributor because hyperalgesia is reduced when TRPV1 is either genetically deleted or pharmacologically blocked. Inflammatory mediators such as prostaglandin-E2 or bradykinin cause hyperalgesia by activating cellular kinases that phosphorylate TRPV1, a process that has recently been shown to rely on a scaffolding protein, AKAP79, to target the kinases to TRPV1. Here we use Förster resonance energy transfer, immunoprecipitation, and TRPV1 membrane trafficking experiments to identify a key region on AKAP79, between amino acids 326–336, which is responsible for its interaction with TRPV1. A peptide identical to this domain inhibited sensitization of TRPV1 in vitro, and when covalently linked to a TAT peptide to promote uptake across the cell membrane the peptide inhibited in vivo inflammatory hyperalgesia in mice. Critically, it did so without affecting pain thresholds in the absence of inflammation. These results suggest that antagonizing the TRPV1–AKAP79 interaction will be a useful strategy for inhibiting inflammatory hyperalgesia. PMID:23699529

  6. The ion channel TRPV1 regulates the activation and proinflammatory properties of CD4⁺ T cells.

    PubMed

    Bertin, Samuel; Aoki-Nonaka, Yukari; de Jong, Petrus Rudolf; Nohara, Lilian L; Xu, Hongjian; Stanwood, Shawna R; Srikanth, Sonal; Lee, Jihyung; To, Keith; Abramson, Lior; Yu, Timothy; Han, Tiffany; Touma, Ranim; Li, Xiangli; González-Navajas, José M; Herdman, Scott; Corr, Maripat; Fu, Guo; Dong, Hui; Gwack, Yousang; Franco, Alessandra; Jefferies, Wilfred A; Raz, Eyal

    2014-11-01

    TRPV1 is a Ca(2+)-permeable channel studied mostly as a pain receptor in sensory neurons. However, its role in other cell types is poorly understood. Here we found that TRPV1 was functionally expressed in CD4(+) T cells, where it acted as a non-store-operated Ca(2+) channel and contributed to T cell antigen receptor (TCR)-induced Ca(2+) influx, TCR signaling and T cell activation. In models of T cell-mediated colitis, TRPV1 promoted colitogenic T cell responses and intestinal inflammation. Furthermore, genetic and pharmacological inhibition of TRPV1 in human CD4(+) T cells recapitulated the phenotype of mouse Trpv1(-/-) CD4(+) T cells. Our findings suggest that inhibition of TRPV1 could represent a new therapeutic strategy for restraining proinflammatory T cell responses. PMID:25282159

  7. Shp-1 dephosphorylates TRPV1 in dorsal root ganglion neurons and alleviates CFA-induced inflammatory pain in rats.

    PubMed

    Xiao, Xing; Zhao, Xiao-Tao; Xu, Ling-Chi; Yue, Lu-Peng; Liu, Feng-Yu; Cai, Jie; Liao, Fei-Fei; Kong, Jin-Ge; Xing, Guo-Gang; Yi, Ming; Wan, You

    2015-04-01

    Transient receptor potential vanilloid 1 (TRPV1) receptors are expressed in nociceptive neurons of rat dorsal root ganglions (DRGs) and mediate inflammatory pain. Nonspecific inhibition of protein-tyrosine phosphatases (PTPs) increases the tyrosine phosphorylation of TRPV1 and sensitizes TRPV1. However, less is known about tyrosine phosphorylation's implication in inflammatory pain, compared with that of serine/threonine phosphorylation. Src homology 2 domain-containing tyrosine phosphatase 1 (Shp-1) is a key phosphatase dephosphorylating TRPV1. In this study, we reported that Shp-1 colocalized with and bound to TRPV1 in nociceptive DRG neurons. Shp-1 inhibitors, including sodium stibogluconate and PTP inhibitor III, sensitized TRPV1 in cultured DRG neurons. In naive rats, intrathecal injection of Shp-1 inhibitors increased both TRPV1 and tyrosine-phosphorylated TRPV1 in DRGs and induced thermal hyperalgesia, which was abolished by pretreatment with TRPV1 antagonists capsazepine, BCTC, or AMG9810. Complete Freund's adjuvant (CFA)-induced inflammatory pain in rats significantly increased the expression of Shp-1, TRPV1, and tyrosine-phosphorylated TRPV1, as well as the colocalization of Shp-1 and TRPV1 in DRGs. Intrathecal injection of sodium stibogluconate aggravated CFA-induced inflammatory pain, whereas Shp-1 overexpression in DRG neurons alleviated it. These results suggested that Shp-1 dephosphorylated and inhibited TRPV1 in DRG neurons, contributing to maintain thermal nociceptive thresholds in normal rats, and as a compensatory mechanism, Shp-1 increased in DRGs of rats with CFA-induced inflammatory pain, which was involved in protecting against excessive thermal hyperalgesia. PMID:25790452

  8. LE135, a retinoid acid receptor antagonist, produces pain through direct activation of TRP channels

    PubMed Central

    Yin, Shijin; Luo, Jialie; Qian, Aihua; Yu, Weihua; Hu, Hongzhen

    2014-01-01

    Background and PurposeRetinoids, through their activation of retinoic acid receptors (RARs) and retinoid X receptors, regulate diverse cellular processes, and pharmacological intervention in their actions has been successful in the treatment of skin disorders and cancers. Despite the many beneficial effects, administration of retinoids causes irritating side effects with unknown mechanisms. Here, we demonstrate that LE135 [4-(7,8,9,10-tetrahydro-5,7,7,10,10-pentamethyl-5H-benzo[e]naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid], a selective antagonist of RARβ, is a potent activator of the capsaicin (TRPV1) and wasabi (TRPA1) receptors, two critical pain-initiating cation channels. Experimental ApproachWe performed to investigate the excitatory effects of LE135 on TRPV1 and TRPA1 channels expressed in HEK293T cells and in dorsal root ganglia neurons with calcium imaging and patch-clamp recordings. We also used site-directed mutagenesis of the channels to determine the structural basis of LE135-induced activation of TRPV1 and TRPA1 channels and behavioural testing to examine if pharmacological inhibition and genetic deletion of the channels affected LE135-evoked pain-related behaviours. Key ResultsLE135 activated both the capsaicin receptor (TRPV1) and the allyl isothiocyanate receptor (TRPA1) heterologously expressed in HEK293T cells and endogenously expressed by sensory nociceptors. Mutations disrupting the capsaicin-binding site attenuated LE135 activation of TRPV1 channels and a single mutation (K170R) eliminated TRPA1 activity evoked by LE135. Intraplantar injection of LE135 evoked pain-related behaviours. Both TRPV1 and TRPA1 channels were involved in LE135-elicited pain-related responses, as shown by pharmacological and genetic ablation studies. Conclusions and ImplicationsThis blocker of retinoid acid signalling also exerted non-genomic effects through activating the pain-initiating TRPV1 and TRPA1 channels. PMID:24308840

  9. Positive allosteric modulation of TRPV1 as a novel analgesic mechanism

    PubMed Central

    2012-01-01

    Background The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C- and lightly-myelinated Aδ-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing nerve terminals. The loss of

  10. Differential bitterness in capsaicin, piperine, and ethanol associates with polymorphisms in multiple bitter taste receptor genes.

    PubMed

    Nolden, Alissa A; McGeary, John E; Hayes, John E

    2016-03-15

    To date, the majority of research exploring associations with genetic variability in bitter taste receptors has understandably focused on compounds and foods that are predominantly or solely perceived as bitter. However, other chemosensory stimuli are also known to elicit bitterness as a secondary sensation. Here we investigated whether TAS2R variation explains individual differences in bitterness elicited by chemesthetic stimuli, including capsaicin, piperine and ethanol. We confirmed that capsaicin, piperine and ethanol elicit bitterness in addition to burning/stinging sensations. Variability in perceived bitterness of capsaicin and ethanol were significantly associated with TAS2R38 and TAS2R3/4/5 diplotypes. For TAS2R38, PAV homozygotes perceived greater bitterness from capsaicin and ethanol presented on circumvallate papillae, compared to heterozygotes and AVI homozygotes. For TAS2R3/4/5, CCCAGT homozygotes rated the greatest bitterness, compared to heterozygotes and TTGGAG homozygotes, for both ethanol and capsaicin when presented on circumvallate papillae. Additional work is needed to determine how these and other chemesthetic stimuli differ in bitterness perception across concentrations and presentation methods. Furthermore, it would be beneficial to determine which TAS2R receptors are activated in vitro by chemesthetic compounds. PMID:26785164