![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
NEUROPHARMACOLOGY
Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois
Received for publication
January 21, 2005
Accepted
April 14, 2005.
 |
Abstract |
|---|
 Top Abstract Materials and MethodsResultsDiscussionReferences |
|---|
; Tominaga et al., 1998). TRPV1 is also activated or potentiated by endovanilloids, such as anandamide, N-arachidonoyl-dopamine (NADA) (Huang et al., 2002), and N-oleoyl-dopamine (Chu et al., 2003) as well as eicosanoids, such as 12-hydroper-oxyeicosatetraenoic acid (Hwang et al., 2000).
An interesting property of this channel is that these diverse stimuli not only directly activate TRPV1 but also sensitize and reduce the activation thresholds of the channel to other stimuli (Di Marzo et al., 2002). For example, exposure of TRPV1-expressing cells to acidic conditions sensitizes the channel to activation by heat or by capsaicin (Tominaga et al., 1998). In addition, several studies have shown that TRPV1 receptors can be sensitized by inflammatory agents, including bradykinin, NGF, and ATP, acting via second messengers downstream of receptors for these agents (Cortright and Szallasi, 2004). Direct activation of PKC by phorbol 12-myristate 13-acetate (PMA) or phorbol-12,13-dibutyrate (PDBu) leads to similar sensitization of TRPV1 responses to other stimuli (Di Marzo et al., 2002; El Kouhen et al., 2003). These data suggest that TRPV1 plays a key role in the integration of noxious signals after inflammation or tissue injury.
The prototypic TRPV1 receptor antagonist capsazepine has been extensively studied and shown to inhibit nocifensive and hyperalgesic responses not only to capsaicin but also to inflammatory agents (Nagy et al., 2004). However, capsazepine has only modest potency and low specificity, also antagonizing voltage-activated calcium channels (Docherty et al., 1997), acetylcholine receptors (Liu and Simon, 1997), and hyperpolarizing-activated cyclic nucleotide-gated channels such as HCN1 (Gill et al., 2004). Efforts from several groups have been directed to the development of novel TRPV1 receptor antagonists with improved potency and/or selectivity compared with capsazepine. For example, arginine-rich peptides have been reported as TRPV1 blockers with analgesic activities (Planells-Cases et al., 2000). Other TRPV1 antagonists have been described recently, including N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyr-azine-1(2H)-carbox-amide (Valenzano et al., 2003), JYL1421 and KJM429 (Wang et al., 2002), SB-366791 (Gunthorpe et al., 2004), N-(4-chlorobenzyl)-N'-(4-hydroxy-3-iodo-5-methoxybenzyl)thiourea (Toth et al., 2004), compound 41 (Swanson et al., 2005), AMG9810 (Doherty et al., 2005), and 5-iodo-resiniferatoxin (Wahl et al., 2001). The present studies were carried out to characterize a novel TRPV1 receptor antagonist A-425619 that was optimized from hits identified by high-throughput screening of chemical libraries (Gomtsyan et al., 2005).
|
Materials and Methods |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Ca2+ Flux Assay. Cloning and stable expression of the human TRPV1 receptor in HEK293 cells have been previously detailed (Witte et al., 2002). TRPV1-mediated elevation of intracellular calcium levels was measured using the fluorescent calcium chelating dye fluo-4, as described previously (Smart et al., 2001). Briefly, cells were grown as a monolayer in black-walled clear bottom 96-well Biocoat plates (precoated with poly-D-lysine) (BD Biosciences, San Jose, CA). Growth medium was comprised of Dulbecco's modified Eagle's medium (DMEM) (with 4.5 mg/ml D-glucose), 4 mM L-glutamine, 300 µg/ml G-418 sulfate, and 10% (v/v) fetal bovine serum. Prior to the start of the assay, the cells were incubated with 2 µM (acetyloxy)methyl ester form of fluo-4 (fluo-4 AM) in D-PBS for 2 h at 25°C. Subsequently, cells were washed with D-PBS to remove extra-cellular fluo-4 AM, and 100 to 150 µl of D-PBS was added to each well. In some experiments, cells were pretreated with 100 nM PDBu in D-PBS for 20 min at 25°C to sensitize TRPV1 to capsaicin, NADA, or heat. All test compounds were dissolved in DMSO (10 mM stocks), except NADA (5 mg/ml in ethanol) and ruthenium red (10 mM in dH20), and then diluted in D-PBS to obtain (4x) solutions. Test compounds (50 µl of the 4x solutions) were added to the cells at a delivery rate of 50 µl/s. Antagonists were added to the cells 5 min before addition of agonist, and final assay volume was 200 µl. Acid activation studies of the TRPV1 receptor were performed in a similar manner, except ambient pH was lowered to pH 6.7 to facilitate detection of a pure TRPV1-mediated increased intracellular Ca2+. Antagonist solutions were prepared in the ambient pH buffer. Acidic pH solutions were prepared by titration of D-PBS with 1 M HCl, and then 50 µl was added to the cells at a delivery rate of 50 µl/s. For heat activation studies, the liquid contents of the wells were aspirated and replaced with 50 µl of D-PBS or test compound solution at ambient room temperature (25°C). A 96-well assay plate of D-PBS (250 µl/well) was preheated on a hot orbital shaker (Daigger, Vernon Hills, IL) to 50°C, and then 150 µl of heated solution was added to the cells at a delivery rate of 50 µl/s to attain a peak temperature of 38°C. Peak temperature was determined using a TH-1 Therm probe (Cell MicroControls, Norfolk, VA). Changes in fluorescence were recorded over time in a fluorometric imaging plate reader (FLIPR) (Molecular Devices, Sunnyvale, CA) (
EX = 488 nm, EM = 540 nm). Antagonists were tested at 11 concentrations (indicated on each graph). The peak increase in fluorescence over baseline [relative fluorescence units (RFU)] was calculated and expressed as a percentage of the maximal agonist response (in absence of antagonist). EC50 and IC50 values were calculated from curve fits of the concentration-effect data using a four-parameter logistic Hill equation (GraphPad Prism; GraphPad Software Inc., San Diego, CA). Significant differences were calculated by unpaired, two-tailed Student's t tests.
Dorsal Root Ganglion (DRG) Neuronal Cultures. Adult male Sprague-Dawley rats (
8 weeks old, 250–300 g) were deeply anesthetized with CO2 and sacrificed. Lumbar (L4–L6) DRG were dissected from the vertebral column and placed in DMEM (Hyclone Laboratories, Logan, UT) containing 0.3% collagenase B (Roche Diagnostics, Indianapolis, IN) for 60 min at 37°C. The collagenase was replaced with 0.25% trypsin (Invitrogen) in Ca2+/Mg2+-free D-PBS, and further digested for 30 min at 37°C. After washing in fresh DMEM, ganglia were dissociated by trituration using a fire-polished Pasteur pipette. Cells were washed in fresh DMEM and triturated again using a smaller bore fire-polished pipette to obtain a single-cell suspension. DRG cells were then plated on polyethylenimine-treated 12-mm glass coverslips. Cells were plated at a density of one DRG per coverslip in 1 ml of DMEM supplemented with 10% fetal bovine serum, NGF (50 ng/ml), and 100 U/ml Pen/Strep. Neurons were used for electrophysiological recording within 12 to 24 h. Experimental procedures involving rats were conducted under a protocol approved by an Institutional Animal Care and Use Committee.
Electrophysiology. Rat DRGs were maintained at room temperature in an extracellular recording solution (pH 7.4, 325 mOsm) consisting of 155 mM NaCl, 5 mM KCl, 2 mM CaCl2, 1 mM MgCl2,10 mM HEPES, and 12 mM glucose. Patch pipettes composed of borosilicate glass (1B150F-3; World Precision Instruments, Inc., Sara-sota, FL), were pulled and fire-polished using a DMZ-Universal micropipette puller (Zeitz, Augsburg, Germany). Pipettes (2–6 M
) were filled with an internal solution (pH 7.3, 295 mOsm) consisting of 122.5 mM K-aspartate, 20 mM KCl, 1 mM MgCl2, 10 mM EGTA, 5 mM HEPES, and 2 mM ATP·Mg. Standard whole-cell recording techniques were utilized for voltage-clamp studies using an Axopatch 200B amplifier (Axon Instruments Inc., Union City, CA) (Hamill et al., 1981).
Cells were continuously perfused with extracellular solution at a rate of 0.5 ml/min. Capsaicin was applied to small- to medium-sized neurons (25- to 35-µm diameter) for 5 s using a piezoelectric-driven theta-tube application device (Burleigh Instruments, Fishers, NY) controlled by Axon Instruments pClamp 9 software (Axon Instruments Inc.). Control responses typically ran down for the first 5 to 10 min following whole-cell configuration. Therefore, capsaicin was applied alone at 2-min intervals until successive applications produced currents of similar amplitude. At this point, increasing concentrations of A-425619 were preapplied to the neuron for 60 s, followed by coapplication of capsaicin and A-425619. Peak current amplitudes were measured and plotted as a function of antagonist concentration. In a subset of neurons, the washout of the inhibition by A-425619 was monitored by continuing application of capsaicin at 2-min intervals while applying external solution to the cell. Current amplitudes were typically recovered to >80% of control responses within 4 to 6 min.
For electrophysiological studies, a 10 mM stock solution of A-425619 dissolved in DMSO was serially diluted 1:10 in DMSO. On the day of recording, the resulting stock solutions were diluted 1:1000 or 1:333 into external solution for the final concentrations. DMSO alone at these concentrations had no effect on capsaicin-activated currents.
|
|
Results |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
; Witte et al., 2002). Figure 1 shows representative FLIPR tracings following activation of TRPV1 receptors by different stimuli. Addition of 50 nM capsaicin, a concentration equivalent to EC50 (Fig. 2A), elicited a rapid and a robust increase in intracellular calcium concentrations with a maximum response obtained within 10 to 20 s (Fig. 1A). Untransfected HEK293 cells (null) showed no response to capsaicin. Concentrations equivalent to EC50 values of NADA (3 µM) and anandamide (10 µM) (Fig. 2A) evoked a response similar to that evoked by capsaicin (Fig. 1, B and C). Both anandamide and NADA behaved as less potent agonists at the TRPV1 receptor with maximum calcium signals occurring at 60 to 120 s. Note that NADA and anandamide also produced small calcium signals (10%) in null HEK293 cells, indicating that these endogenous ligands evoked non-TRPV1 receptor-mediated responses in addition to activating TRPV1 (Fig. 1, B and C). Acid activation of TRPV1 receptors was performed by reducing the extracellular pH, as described under Materials and Methods. As shown in Fig. 1D, the acid (pH 5.5)-evoked increased intracellular calcium response was immediate and transient. This effect was specific to the TRPV1 receptor since no acid response was observed with null HEK293 cells (Figs. 1D and 2B).
|
|
|
|
A-425619 was also very potent in blocking TRPV1 activation by 3 µM NADA (IC50 = 4 nM) or 10 µM anandamide (IC50 = 3 nM), with a rank order of potencies of A-425619 > I-RTX > capsazepine > ruthenium red (Fig. 4, B and C). However, the activation of TRPV1 receptor-mediated Ca2+ flux evoked by either NADA or anandamide was not completely inhibited by any of the TRPV1 receptor antagonists (Fig. 4, B and C). These data are consistent with results obtained in null HEK293 cells (Fig. 1), which indicate that these ligands induced a small, non-TRPV1 receptor-mediated increased intracellular calcium in addition to activating TRPV1 receptors. This nonspecific effect was more evident in the case of anandamide, where 30% of the total response was unaffected by TRPV1 receptor antagonists (Fig. 4C).
A-425619 was highly potent in blocking activation of TRPV1 receptors by acid (pH 5.5) (Fig. 4D). The rank order of potencies was A-425619 (2 nM) > capsazepine (50 nM) > I-RTX (88 nM) > ruthenium red (386 nM) (Fig. 4D). The pIC50 and Hill slope values for A-425619 and other antagonists in blocking TRPV1 activation by different stimuli are summarized in Table 1.
A-425619 Is a Potent Antagonist at the Native Rat TRPV1 Receptor. The ability of A-425619 to block native TRPV1 receptor activation was examined electrophysiologically in cultured rat DRG neurons, as described under Materials and Methods. Application of 1 µM capsaicin to small-diameter neurons clamped at -70 mV elicited large inward currents. Capsaicin-evoked currents were reduced in the presence of A-425619 in a concentration-dependent manner (IC50 = 9 nM) and were completely blocked at 100 nM (Fig. 5). TRPV1 receptor block by A-425619 was reversible since capsaicin-evoked currents were recovered following antagonist washout (Fig. 5A). Additionally, A-425619 was able to potently block the activation of TRPV1 receptors by endogenous ligands. Anandamide (10 µM) elicited a large current that was fully blocked by 100 nM A-425619 (data not shown).
|
|
A-425619 Is a Competitive Antagonist at the TRPV1 Receptor. To determine the nature of A-425619 antagonism at the TRPV1 receptor, capsaicin concentration-effect curves were determined in the presence of increasing concentrations of A-425619. Figure 6A shows that capsaicin concentration-effect curves were shifted to the right with increasing A-425619 concentrations, without affecting the maximal capsaicin response. This indicates that A-425619 acts as a competitive antagonist at the TRPV1 receptor capsaicin-binding site. A Schild plot analysis yielded a pA2 of 2.5 nM and a slope factor of 1.06 ± 0.05 (Fig. 6B). Under the same conditions, concentration response curves for capsaicin were generated with increasing concentrations of capsazepine and ruthenium red. Consistent with competitive antagonism by capsazepine, capsaicin dose-response curves were shifted to the right as a function of increasing concentrations of capsazepine, without change in the maximal responses (slope = 1.16 ± 0.08) (Fig. 6C). In contrast, increasing concentrations of the antagonist ruthenium red induced a large decrease in the efficacy of capsaicin to stimulate calcium flux with a small rightward shift of the capsaicin dose-response curves (Fig. 6D), consistent with noncompetitive antagonism.
|
A-425619 Is a Potent Antagonist at the Sensitized TRPV1 Receptor. Agents such as heat, acid, and endovanilloids not only activate TRPV1 receptors but also sensitize the channel responses to other stimuli (Cortright and Szallasi, 2004). We recently reported that sensitization of TRPV1 under acidic conditions involves receptor phosphorylation and that PKC plays an important role in this acid-induced sensitization (El Kouhen et al., 2003). The ability of A-425619 to block the activation of sensitized TRPV1 receptors was investigated under different conditions. In the presence of 100 nM PDBu or pH 6.0, the potency of capsaicin to stimulate increased intracellular calcium was enhanced 2- to 4-fold (control capsaicin concentration-effect curves in the absence of antagonist; Fig. 7, A and B). EC50 values for capsaicin were 8.5 and 15 nM, after PDBu and acid pretreatment, respectively (Fig. 7, A and B). The EC50 value for capsaicin to activate the naive TRPV1 receptor was 50 nM. In the presence of increasing concentrations of A-425619, concentration-effect curves of capsaicin were shifted to the right (Fig. 7, A and B). Schild plot analysis yielded pA2 values of 0.8 and 4.3 nM after sensitization by PDBu and acid, respectively (Fig. 7C). These pA2 values were not significantly different (p > 0.05) from that generated in naive conditions (2.5 nM) (Fig. 6B) and showed that A-425619 remained a potent antagonist at sensitized TRPV1 receptors. The rank order of potencies for antagonist block of sensitized TRPV1 was the same as that in blocking activation of naive TRPV1, A-425619 > I-RTX > capsazepine > ruthenium red (Fig. 8; Table 3).
|
|
|
The ability of heat to activate TRPV1 receptors was also assessed in the calcium flux assay on both naive and PDBu-sensitized channels, as described under Materials and Methods. A small but significant response was observed in TRPV1 receptor-expressing HEK293 cells in response to heat (38°C). This signal was dramatically increased when the cells were pretreated for 20 min with the PKC activator PDBu (100 nM) (Fig. 9A). However, the increased intracellular calcium evoked by heat in PDBu-treated cells (see Materials and Methods) was transient and much shorter in duration than that induced by other stimuli (Fig. 1). The transient nature of this response may be due, at least in part, to the methodology used as well as to the response of the channel to heat. The small heat-evoked signal obtained in null cells was unaffected by the PDBu pretreatment (Fig. 9A). The ability of A-425619 and other antagonists to block the response of the sensitized TRPV1 receptor to heat was also examined. A-425619 effectively attenuated this response and was approximately 25- and 50-fold more potent than I-RTX and capsazepine, respectively (Fig. 9B; Table 3).
|
|
Discussion |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
It is now generally accepted that TRPV1 is an integrator of multiple and diverse stimuli, such as vanilloids, acid (pH < 6.0), heat (>43°C), and endogenous arachidonic acid derivatives (Caterina et al., 1997; Tominaga et al., 1998). These agents can directly activate TRPV1 receptors as well as sensitize channel responses to other noxious stimuli (Di Marzo et al., 2002). Moreover, inflammatory agents, including ATP, NGF, and bradykinin, can potentiate TRPV1 responses by activating specific kinases, which phosphorylate the TRPV1 channel (Di Marzo et al., 2002). Interestingly, both NGF and bradykinin also induce the hydrolysis of phosphatidylinositol (4,5)-biphosphate, which leads to the release of TRPV1 receptor from an inhibited state (Chuang et al., 2001). These studies indicate that the TRPV1 channel is regulated by multiple mechanisms and support the importance of this channel in pain transmission during inflammation or tissue injury.
The present work demonstrates that the structurally novel TRPV1 receptor antagonist A-425619 is 25- to 50-fold more potent than capsazepine in blocking activation of TRPV1 receptors by a variety of stimuli, including capsaicin, acid, heat, NADA, and anandamide. A-425619 completely blocked TRPV1 activation by capsaicin, acid, and heat. However, the calcium flux induced by NADA and anandamide was not fully blocked by A-425619, consistent with previous reports, that NADA and anandamide have additional activities, including effects on fatty acid amide hydrolase and cannabinoid CB1 receptors (Huang et al., 2002; Chu et al., 2003). Moreover, in vitro and in vivo studies with capsazepine have been difficult to interpret due to the low selectivity of this antagonist for blocking TRPV1 receptors (Nagy et al., 2004). Thus, the availability of highly potent and selective antagonists of TRPV1 receptors not only will help to elucidate the complex pharmacology of this interesting channel but also may have therapeutic potential as novel analgesics.
Consistent with other reports, both acid and PDBu pre-treatments reduced activation thresholds of TRPV1 receptors by capsaicin, heat, anandamide, or NADA (El Kouhen et al., 2003; Cortright and Szallasi, 2004). Interestingly, here we provide evidence that A-425619 effectively blocked the activation of both naive and sensitized TRPV1 channels. Sensi-tization or phosphorylation of TRPV1 seems to increase the affinity of the channel to agonist e.g., capsaicin (Premkumar and Ahern, 2000; Vellani et al., 2001). However, a Schild plot analysis indicated that the affinity of A-425619 to block sensitized TRPV1 receptors remained comparable with that blocking naive TRPV1 receptors. The present data suggest that TRPV1 antagonists such as A-425619 may serve as an effective tool in blocking TRPV1 activation during inflammation or tissue injury.
Like capsazepine, A-425619 competitively blocked the ability of capsaicin to stimulate calcium flux through TRPV1 receptors. The capsaicin recognition site has been proposed to be predominantly localized on intracellular domains of TRPV1 (Jung et al., 1999; Jordt and Julius, 2002), although there is evidence of an extracellular domain as well (Vyklicky et al., 2003). In contrast, the proton interaction site is proposed to be extracellular (Jordt et al., 2000). Since A-425619 blocks activation of TRPV1 receptors by multiple stimuli, it is possible that this compound blocks or modulates the gating mechanism of the channel. It has been reported that the noncompetitive antagonist ruthenium red blocks the activation of TRPV1 channels by different stimuli through blocking of the channel gating (Czirjak and Enyedi, 2003). Alternatively, protons and heat could act as TRPV1 modulators by sensitizing the channel to activation by endogenous vanilloids. In this case, A-425619 would inhibit proton, heat, or PDBu activation of TRPV1 by competing for recognition site(s) for capsaicin or endogenous vanilloids. Evidence supporting this latter interpretation comes from demonstrations that the potency and efficacy of anandamide to activate TRPV1 receptors is greatly enhanced under acidic conditions (Premkumar and Ahern, 2000; Vellani et al., 2001). Although the exact mode by which capsaicin-competitive antagonists block TRPV1 receptor activation in response to other stimuli remains unclear, the present data demonstrate that A-425619 can effectively block TRPV1 receptor activation by a variety of pronociceptive stimuli and that the potency of this antagonist for TRPV1 receptors is largely unaffected by the state of channel activation. The present data show that A-425619 serves as a useful tool to enhance the understanding of the complex TRPV1 pharmacology. In addition, the structurally novel TRPV1 antagonist A-425619 will be useful in defining the analgesic potential of blockade of TRPV1 in vivo (Honore et al., 2005).
|
Footnotes |
|---|
ABBREVIATIONS: TRPV1, transient receptor potential type V1; NADA, N-arachidonoyl-dopamine; NGF, nerve growth factor; PKC, protein kinase C; PDBu, phorbol-12,13-dibutyrate; SB-366791, SN-(3-methoxyphenyl)-4-chlorocinnamide; compound 41, 4-(3-trifluoromethylpyridin-2-yl)piperazine-1-carboxylic acid (5-trifluoromethyl pyridin-2-yl)amide; AMG9810, (E)-3-(4-t-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide; A-425619, 1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea; D-PBS, Dulbecco's phosphate-buffered saline; DMEM, Dulbecco's modified Eagle's medium; AM, acetoxymethyl ester; DMSO, dimethyl sulfoxide; FLIPR, fluorometric imaging plate reader; RFU, relative fluorescence unit(s); DRG, dorsal root ganglion; I-RTX, 5-iodo-resiniferatoxin; JYL1421, N-(4-tert-butylbenzyl)-N'-[3-fluoro-4-(methylsulfonylamino)benzyl]thiourea; KJM429, N-(4-tert-butylbenzyl)-N'-[4-(methylsulfonylamino)benzyl]thiourea.
Address correspondence to: Dr. Rachid El Kouhen, Abbott Laboratories, R4PM, AP9A/2, 100 Abbott Park Road, Abbott Park, IL 60064-6123. E-mail: rachid.elkouhen{at}abbott.com
|
References |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Caterina MJ, Schumacher MA, Tominaga M, Rosen TA, Levine JD, and Julius D (1997) The capsaicin receptor: a heat-activated ion channel in the pain pathway. Nature (Lond) 389: 816-824.[CrossRef][Medline]
Chu CJ, Huang SM, De Petrocellis L, Bisogno T, Ewing SA, Miller JD, Zipkin RE, Daddario N, Appendino G, Di Marzo V, et al. (2003) N-Oleoyldopamine, a novel endogenous capsaicin-like lipid that produces hyperalgesia. J Biol Chem 278: 13633-13639.
Chuang HH, Prescott ED, Kong H, Shields S, Jordt SE, Basbaum AI, Chao MV, and Julius D (2001) Bradykinin and nerve growth factor release the capsaicin receptor from PtdIns(4,5)P2-mediated inhibition. Nature (Lond) 411: 957-962.[CrossRef][Medline]
Cortright DN and Szallasi A (2004) Biochemical pharmacology of the vanilloid receptor TRPV1. An update. Eur J Biochem 271: 1814-1819.[Medline]
Czirjak G and Enyedi P (2003) Ruthenium red inhibits TASK-3 potassium channel by interconnecting glutamate 70 of the two subunits. Mol Pharmacol 63: 646-652.
Di Marzo V, Blumberg PM, and Szallasi A (2002) Endovanilloid signaling in pain. Curr Opin Neurobiol 12: 372-379.[CrossRef][Medline]
Docherty RJ, Yeats JC, and Piper AS (1997) Capsazepine block of voltage-activated calcium channels in adult rat dorsal root ganglion neurons in culture. Br J Pharmacol 121: 1461-1467.[CrossRef][Medline]
Doherty EM, Fotsch C, Bo Y, Chakrabarti PP, Chen N, Gavva N, Han N, Kelly MG, Kincaid J, Klionsky L, et al. (2005) Discovery of potent, orally available vanilloid receptor-1 antagonists: structure-activity relationship of N-aryl cinnamides. J Med Chem 48: 71-90.[CrossRef][Medline]
El Kouhen R, Bianchi BR, Estvander BR, Surowy CS, Jarvis MF, and Faltynek CR (2003) Correlation between phosphorylation and sensitization of the VR1 receptor. Program No. 811.4. 2003 Abstract Viewer and Itinerary Planner. New Orleans, LA: Society for Neuroscience, Online.
Gill CH, Randall A, Bates SA, Hill K, Owen D, Larkman PM, Cairns W, Yusaf SP, Murdock PR, Strijbos PJ, et al. (2004) Characterization of the human HCN1 channel and its inhibition by capsazepine. Br J Pharmacol 143: 411-421.[CrossRef][Medline]
Gomtsyan A, Bayburt EK, Schmidt RG, Zheng GZ, Perner RJ, Didomineco S, Koenig JR, Turner S, Jinkerson T, Drizin I, et al. (2005) Novel transient receptor potential vanilloid 1 (TRPV1) receptor antagonists for the treatment of pain: structure-activity relationships for ureas with quinoline, isoquinoline, quinazoline, phthalazine, quinoxaline and cinnoline moieties. J Med Chem 48: 744-752.[CrossRef][Medline]
Gunthorpe MJ, Rami HK, Jerman JC, Smart D, Gill CH, Soffin EM, Luis Hannan S, Lappin SC, Egerton J, Smith GD, et al. (2004) Identification and characterization of SB-366791, a potent and selective vanilloid receptor (VR1/TRPV1) antagonist. [Erratum in Neuropharmacology (2004) 46:905] Neuropharmacology 46: 133-149.[CrossRef][Medline]
Hamill OP, Marty A, Neher E, Sakmann B, and Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch 391: 85-100.[CrossRef][Medline]
Honore P, Wismer CT, Mikusa J, Zhu CZ, Zhong C, Gauvin D, Gomtsyan A, El Kouhen R, Lee CH, Marsh K, et al. (2005) A-425619 [1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea], a novel transient receptor potential type V1 receptor antagonist, relieves pathophysiological pain associated with inflammation and tissue injury in rats. J Pharmacol Exp Ther 314: 410-421.
Huang SM, Bisogno T, Trevisani M, Al-Hayani A, De Petrocellis L, Fezza F, Tognetto M, Petros TJ, Krey JF, Chu CJ, et al. (2002) An endogenous capsaicin-like substance with high potency at recombinant and native vanilloid VR1 receptors. Proc Natl Acad Sci USA 99: 8400-8405.
Hwang SW, Cho H, Kwak J, Lee SY, Kang CJ, Jung J, Cho S, Min KH, Suh YG, Kim D, and Oh U (2000) Direct activation of capsaicin receptors by products of lipoxygenases: endogenous capsaicin-like substances. Proc Natl Acad Sci USA 97: 6155-6160.
Jordt SE and Julius D (2002) Molecular basis for species-specific sensitivity to "hot" chili peppers. Cell 108: 421-430.[CrossRef][Medline]
Jordt SE, Tominaga M, and Julius D (2000) Acid potentiation of the capsaicin receptor determined by a key extracellular site. Proc Natl Acad Sci USA 97: 8134-8139.
Jung J, Hwang SW, Kwak J, Lee SY, Kang CJ, Kim WB, Kim D, and Oh U (1999) Capsaicin binds to the intracellular domain of the capsaicin-activated ion channel. J Neurosci 19: 529-538.
Liu L and Simon SA (1997) Capsazepine, a vanilloid receptor antagonist, inhibits nicotinic acetylcholine receptors in rat trigeminal ganglia. Neurosci Lett 228: 29-32.[CrossRef][Medline]
Nagy I, Santha P, Jancso G, and Urban L (2004) The role of the vanilloid (capsaicin) receptor (TRPV1) in physiology and pathology. Eur J Pharmacol 500: 351-369.[CrossRef][Medline]
Planells-Cases R, Aracil A, Merino JM, Gallar J, Perez-Paya E, Belmonte C, Gonzalez-Ros JM, and Ferrer-Montiel AV (2000) Arginine-rich peptides are blockers of VR-1 channels with analgesic activity. FEBS Lett 481: 131-136.[CrossRef][Medline]
Premkumar LS and Ahern GP (2000) Induction of vanilloid receptor channel activity by protein kinase C. Nature (Lond) 408: 985-990.[CrossRef][Medline]
Smart D, Jerman JC, Gunthorpe MJ, Brough SJ, Ranson J, Cairns W, Hayes PD, Randall AD, and Davis JB (2001) Characterisation using FLIPR of human vanilloid VR1 receptor pharmacology. Eur J Pharmacol 417: 51-58.[CrossRef][Medline]
Swanson DM, Dubin AE, Shah C, Nasser N, Chang L, Dax SL, Jetter M, Breiten-bucher JG, Liu C, Mazur C, et al. (2005) Identification and biological evaluation of 4-(3-trifluoromethylpyridin-2-yl)piperazine-1-carboxylic acid (5-trifluoromethylpyridin-2-yl)amide, a high affinity TRPV1 (VR1) vanilloid receptor antagonist. J Med Chem 48: 1857-1872.[CrossRef][Medline]
Tominaga M, Caterina MJ, Malmberg AB, Rosen TA, Gilbert H, Skinner K, Raumann BE, Basbaum AI, and Julius D (1998) The cloned capsaicin receptor integrates multiple pain-producing stimuli. Neuron 21: 531-543.[CrossRef][Medline]
Toth A, Blumberg PM, Chen Z, and Kozikowski AP (2004) Design of a high-affinity competitive antagonist of the vanilloid receptor selective for the calcium entry-linked receptor population. Mol Pharmacol 65: 282-291.
Valenzano KJ, Grant ER, Wu G, Hachicha M, Schmid L, Tafesse L, Sun Q, Rotshteyn Y, Francis J, Limberis J, et al. (2003) N-(4-Tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine -1(2H)-carbox-amide (BCTC), a novel, orally effective vanilloid receptor 1 antagonist with analgesic properties: I. In vitro characterization and pharmacokinetic properties. J Pharmacol Exp Ther 306: 377-386.
Vellani V, Mapplebeck S, Moriondo A, Davis JB, and McNaughton PA (2001) Protein kinase C activation potentiates gating of the vanilloid receptor VR1 by capsaicin, protons, heat and anandamide. J Physiol 534: 813-825.
Vyklicky L, Lyfenko A, Kuffler DP, and Vlachova V (2003) Vanilloid receptor TRPV1 is not activated by vanilloids applied intracellularly. Neuroreport 14: 1061-1065.[CrossRef][Medline]
Wahl P, Foged C, Tullin S, and Thomsen C (2001) Iodo-resiniferatoxin, a new potent vanilloid receptor antagonist. Mol Pharmacol 59: 9-15.
Wang Y, Szabo T, Welter JD, Toth A, Tran R, Lee J, Kang SU, Suh YG, Blumberg PM, and Lee J (2002) High affinity antagonists of the vanilloid receptor. [Erratum in Mol Pharmacol (2003) 63:958] Mol Pharmacol 62: 947-956.
Witte DG, Cassar SC, Masters JN, Esbenshade T, and Hancock AA (2002) Use of a fluorescent imaging plate reader-based calcium assay to assess pharmacological differences between the human and rat vanilloid receptor. J Biomol Screen 7: 466-475.
This article has been cited by other articles:
|
|
 |
|
  A. A. Romanovsky, M. C. Almeida, A. Garami, A. A. Steiner, M. H. Norman, S. F. Morrison, K. Nakamura, J. J. Burmeister, and T. B. Nucci The Transient Receptor Potential Vanilloid-1 Channel in Thermoregulation: A Thermosensor It Is Not Pharmacol. Rev., September 1, 2009; 61(3): 228 - 261. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. M. Sappington, T. Sidorova, D. J. Long, and D. J. Calkins TRPV1: Contribution to Retinal Ganglion Cell Apoptosis and Increased Intracellular Ca2+ with Exposure to Hydrostatic Pressure Invest. Ophthalmol. Vis. Sci., February 1, 2009; 50(2): 717 - 728. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. S. Surowy, T. R. Neelands, B. R. Bianchi, S. McGaraughty, R. El Kouhen, P. Han, K. L. Chu, H. A. McDonald, M. Vos, W. Niforatos, et al. (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 J. Pharmacol. Exp. Ther., September 1, 2008; 326(3): 879 - 888. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Sappington and D. J. Calkins Contribution of TRPV1 to Microglia-Derived IL-6 and NF{kappa}B Translocation with Elevated Hydrostatic Pressure Invest. Ophthalmol. Vis. Sci., July 1, 2008; 49(7): 3004 - 3017. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. R. Bianchi, R. El Kouhen, T. R. Neelands, C.-H. Lee, A. Gomtsyan, S. N. Raja, S. N. Vaidyanathan, B. Surber, H. A. McDonald, C. S. Surowy, et al. [3H]A-778317 [1-((R)-5-tert-Butyl-indan-1-yl)-3-isoquinolin-5-yl-urea]: a Novel, Stereoselective, High-Affinity Antagonist Is a Useful Radioligand for the Human Transient Receptor Potential Vanilloid-1 (TRPV1) Receptor J. Pharmacol. Exp. Ther., October 1, 2007; 323(1): 285 - 293. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Gunthorpe, S. L. Hannan, D. Smart, J. C. Jerman, S. Arpino, G. D. Smith, S. Brough, J. Wright, J. Egerton, S. C. Lappin, et al. Characterization of SB-705498, a Potent and Selective Vanilloid Receptor-1 (VR1/TRPV1) Antagonist That Inhibits the Capsaicin-, Acid-, and Heat-Mediated Activation of the Receptor J. Pharmacol. Exp. Ther., June 1, 2007; 321(3): 1183 - 1192. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. R. Gavva, A. W. Bannon, S. Surapaneni, D. N. Hovland Jr, S. G. Lehto, A. Gore, T. Juan, H. Deng, B. Han, L. Klionsky, et al. The Vanilloid Receptor TRPV1 Is Tonically Activated In Vivo and Involved in Body Temperature Regulation J. Neurosci., March 28, 2007; 27(13): 3366 - 3374. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. J. Caterina Transient receptor potential ion channels as participants in thermosensation and thermoregulation Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R64 - R76. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Cui, P. Honore, C. Zhong, D. Gauvin, J. Mikusa, G. Hernandez, P. Chandran, A. Gomtsyan, B. Brown, E. K. Bayburt, et al. TRPV1 Receptors in the CNS Play a Key Role in Broad-Spectrum Analgesia of TRPV1 Antagonists. J. Neurosci., September 13, 2006; 26(37): 9385 - 9393. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. McGaraughty, K. L. Chu, C. R. Faltynek, and M. F. Jarvis Systemic and Site-Specific Effects of A-425619, a Selective TRPV1 Receptor Antagonist, on Wide Dynamic Range Neurons in CFA-Treated and Uninjured Rats J Neurophysiol, January 1, 2006; 95(1): 18 - 25. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Honore, C. T. Wismer, J. Mikusa, C. Z. Zhu, C. Zhong, D. M. Gauvin, A. Gomtsyan, R. El Kouhen, C.-H. Lee, K. Marsh, et al. A-425619 [1-Isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea], a Novel Transient Receptor Potential Type V1 Receptor Antagonist, Relieves Pathophysiological Pain Associated with Inflammation and Tissue Injury in Rats J. Pharmacol. Exp. Ther., July 1, 2005; 314(1): 410 - 421. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|
 |
 |
 |
