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NGF Up-regulates TRPA1: Implications for Orofacial Pain

¹ Departments of Pharmacology and
² Endodontics, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA

Correspondence: ^* corresponding author, Hargreaves{at}UTHSCSA.edu

	ABSTRACT

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The transient receptor potential ankyrin repeat 1 (TRPA1) channel is believed to be involved in many forms of acute and chronic hyperalgesia. Nerve Growth Factor (NGF) regulates chronic inflammatory hyperalgesia by controlling gene expression in sensory neurons, including genes involved in inflammatory hyperalgesia in the dental pulp. We hypothesized that NGF increases functional activities of the TRPA1 channel in trigeminal ganglion neurons. Here, we show that NGF induced a concentration- and time-dependent up-regulation of TRPA1 mRNA in trigeminal ganglia neurons, as detected by real-time RT-PCR and in situ hybridization. In addition, NGF evoked a time-dependent increase of mustard oil (MO)-evoked TRPA1 activation in trigeminal ganglia neurons. Collectively, these findings demonstrate that NGF participates in the functional up-regulation of TRPA1 in trigeminal ganglia neurons. These enhanced activities of TRPA1 could play an important role in the development of hyperalgesia following nerve injury and inflammation in the orofacial region.

Key Words: TRPA1 • NGF • pain • trigeminal • RT-PCR

	INTRODUCTION

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The transient receptor potential ankyrin repeat 1 (TRPA1) is an ionotropic channel expressed by a subset of capsaicin-sensitive, transient receptor potential vanilloid type 1 (TRPV1)-containing nociceptors (Story et al., 2003). TRPA1 is activated by cold, certain cannabinoids (e.g., 9-tetrahydrocannabinol and WIN) and chemicals, including mustard oil (MO) and allicin (the pungent ingredient of garlic), and is responsible for the nociception and inflammation caused by these stimuli (Story et al., 2003; Jordt et al., 2004; Bautista et al., 2005, 2006; Patwardhan et al., 2006). In addition, recent reports have indicated that TRPA1 is involved in the development of chronic cold hyperalgesia following inflammation, nerve injury, and acute thermal hyperalgesia evoked by bradykinin (Bandell et al., 2004; Obata et al., 2005; Bautista et al., 2006; Katsura et al., 2006; Kwan et al., 2006).

Nerve growth factor (NGF) activates the high-affinity TrkA and the low-affinity P75 receptors, which are expressed in a major subclass of nociceptors, including some nociceptors localized in the orofacial region (Wheeler et al., 1998). The presence of NGF is essential for the development of this subclass of nociceptors (Lewin and Mendell, 1993). Further, NGF is up-regulated in inflamed dental pulp (Wheeler et al., 1998) and plays a significant role in the development of hyperalgesia following inflammation and nerve injury (Lewin and Mendell, 1993; Shu and Mendell, 1999). Activation of NGF receptors in sensory neurons leads to up-regulation of the expression of several genes involved in nociception, including calcitonin gene-related peptide (CGRP) (Bowles et al., 2004; Price et al., 2005) and substance P (Skoff and Adler, 2006).

Based upon these considerations, we hypothesized that NGF alters the expression and function of TRPA1 in trigeminal sensory neurons and tested this hypothesis using in vitro and in vivo molecular and electrophysiological approaches. Demonstration of this interaction might have considerable significance in our understanding of the pathogenesis of orofacial pain, particularly under conditions where NGF is known to be up-regulated (Wheeler et al., 1998).

	METHODS

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Animals
Adult male Sprague-Dawley rats (weight, 200–250 g each) (Charles River, Wilmington, MA, USA) were used in this study. All animal study protocols were approved by the Institutional Animal Care and Use Committee of the University of Texas Health Science Center at San Antonio and conformed to the International Association for the Study of Pain (IASP) and Federal guidelines. Animals were housed for 1 wk prior to the experiments with food and water available ad lib.

Chemicals
For in vivo studies, NGF (Harlan, Indianapolis, IN, USA) was dissolved in saline (final concentration of 1 mg/mL). For in vitro studies, NGF (Harlan) was dissolved in water and diluted in culture media (final concentration of 100 ng/mL) on the day of the experiment. Mustard oil (MO; Sigma, St. Louis, MO, USA) was diluted in standard extracellular solution (SES; see below).

Rat Trigeminal Ganglia Primary Cultures
The trigeminal ganglia dissected from male rats were treated with collagenase-dispase (1 mg/mL; Roche, Bedford, MA, USA), and neuronal cultures were prepared as previously described (Patwardhan et al., 2005).

Intraganglionic NGF Administration
Rats were deeply anesthetized with a ketamine (80 mg/Kg)/xylazine (12 mg/Kg) solution (i.p.; Sigma) and placed in a stereotaxic apparatus (Kopf, Tujunga, CA, USA). A cannula, model 3280P/DW/SPC (Plastics One, Roanoke, VA, USA), was stereotactically inserted into the trigeminal ganglion according to surgical coordinates (relative to bregma: –3.2 mm anteriorly, +3.2 mm laterally, and –10.9 mm in depth) (Schneider et al., 1981). Sterile tubing was used to connect the cannula to an osmotic minipump (model 1007D, Alzet; Cupertino, CA, USA) filled with NGF (1 mg/mL) or vehicle. Dental acrylic cement (Henry Schein, Inc., Melville, NY, USA) was used to fix the cannula to a stainless steel screw (ss/mach cs 0–80 x 1/8"; Small Parts Inc., Miami Lakes, FL, USA) inserted into the skull. The wound was closed with a 4.0 silk suture (Ethicon; San Angelo, TX, USA). Vehicle (isotonic saline) or NGF (0.5 µg/hr) was delivered via intraganglionic (i.gl.) infusion for 7 days. The correct positioning of the cannula placement was verified by microscopic examination at the end of the infusion period.

Systemic NGF Administration
Rats received a daily subcutaneous (s.c.) injection of vehicle (250 µL isotonic saline) or NGF (1 mg/kg) as described previously (Bowles et al., 2004).

RNA Isolation and Real-time PCR
The ground tissues were used to isolate total RNA by the guanidinium thiocyanate method (Chomczynski and Sacchi, 1987). The isolated RNA was then treated with DNA-free reagent (DNAse I; Ambion, Austin, TX, USA). Approximately 1.5 µg of RNA was used for first-strand cDNA synthesis (SuperScript III kit, Invitrogen, Valencia, CA, USA), and cDNA samples equivalent to 100 ng of RNA were used as a template for reactions. Real-time amplification of target sequences was detected by a sequence detector, ABI 7700 (Applied Biosystems, Foster City, CA, USA), utilizing TaqMan Gene Expression Assays on Demand (Applied Biosystems, Foster City, CA, USA), with specific primers and probes for the TRPA1 (assay #Rn01473803), CGRP (assay #Rn00569199), and eukaryotic 18S rRNA genes (assay #Hs99999901_s1). The reactions were run in triplicates of 25 µL as described previously (Diogenes et al., 2006). We normalized the data from the intraganglionic infusion experiment by calculating the ratio of mRNA transcripts measured in the ipsilateral (infused) ganglia compared with values obtained from the contralateral ganglia.

In situ Hybridization (ISH) and Immunohistochemistry (IHC)
In situ hybridization combined with immunohistochemistry was performed in cryosections (20 µm in thickness) of trigeminal ganglia from NGF- or saline-treated rats as described previously (Patwardhan et al., 2005), with a riboprobe against the full-length TRPA1 mRNA (accession #NM_207608) and an antiserum against TRPV1 (Neuromics, Bloomington, MN, USA). Additionally, double-immunohistochemistry was performed in cultured trigeminal neurons grown in the presence of NGF (100 ng/mL) or vehicle for 72 hrs, with validated polyclonal antibodies against TRPA1 and TRPV1 (Jeske et al., 2006). Images were acquired and analyzed as described previously (Diogenes et al., 2006). Double-immunoreactive cells were manually counted from images randomly taken from 6 slides/rat derived from 3 rats/group.

Patch Clamp Electrophysiology
All recordings were performed in whole-cell voltage-clamp (V_h = –60 mV) configuration. Data were acquired at 22–24°C from the somata of trigeminal ganglia neurons, with a capacitance of 15–45 picofarads (pF), an Axopatch200B amplifier, and pCLAMP9.0 software (Axon Instruments, Union City, CA, USA). Cell diameters were calculated according to d = [100*C_m/], where d (µm) is cell diameter and C_m is membrane capacitance in picofarads (pF) (Hille, 2001). Data were filtered at 0.5 kHz and sampled at 2 kHz. Borosilicate pipettes (Sutter, Novato, CA, USA) were polished to resistances of 3–5 M. Access resistance was compensated (40–80%) to a value of 6–10 M. Standard external solution (SES) contained (in mM): 140 NaCl, 5 KCl, 2 CaCl₂, 1 MgCl₂, 10 D-glucose, and 10 HEPES, pH 7.4. The standard pipette solution (SIS) was (in mM): 140 KCl, 1 MgCl₂, 1 CaCl₂, 10 EGTA, 10 D-glucose, 10 HEPES, 0.2 Na-GTP, and 2.5 Mg-ATP, pH 7.3. The test compounds were applied locally by means of a fast, computer-controlled, pressure-driven 8-channel system (ValveLink8; AutoMate Scientific, San Francisco, CA, USA).

	RESULTS

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NGF Up-regulates TRPA1 mRNA in Trigeminal Ganglia Neurons in vitro
To examine the regulation of TRPA1 mRNA expression by NGF, we grew trigeminal ganglia neurons in culture for 24 hrs in the presence of vehicle or various concentrations of NGF. The expression of TRPA1 mRNA was significantly up-regulated by NGF in a concentration-dependent manner (1 ng/mL-100 ng/mL; Fig. 1A). We used the up-regulation of CGRP mRNA by NGF as a positive control to verify bioactivity of the neurotrophin and viability of the trigeminal ganglia cultures (Fig. 1B).

View larger version (28K): [in this window] [in a new window]   Figure 1. NGF up-regulated the expression of TRPA1 mRNA in trigeminal ganglia. NGF concentration-dependently up-regulated the expression of TRPA1 mRNA (A) and CGRP mRNA (B) in the cultured trigeminal ganglia neurons. Trigeminal ganglia neurons were grown in culture in the presence of vehicle or NGF (1–100 ng/mL) for 24 hrs. Total RNA was isolated, and real-time RT-PCR was performed with primers specific for the TRPA1 or CGRP sequences. Data are presented as mean ± SEM (* = p < 0.05 and ** = p < 0.01 vs. vehicle group, one-way ANOVA with Bonferroni’s post hoc test; n = 3 independent cultures/group). Systemic administration of NGF significantly up-regulated the expression of TRPA1 mRNA (C) and CGRP mRNA (D) in trigeminal ganglia neurons. Male rats received a daily subcutaneous injection of vehicle or NGF (1 mg/kg) for 7 days. Total RNA was isolated from the trigeminal ganglia, and real-time RT-PCR was performed with primers specific for the TRPA1 or CGRP sequences. Data are presented as mean ± SEM (n = 3–4/group, ** = p < 0.01 and *** = p < 0.001 vs. vehicle group; two-tailed unpaired t test). Local administration of NGF significantly increased the expression of TRPA1 (E) and CGRP (F) mRNA in the trigeminal ganglia. Rats received intraganglionic (i.gl.) infusion of NGF into the left ganglia at a constant rate of 0.5 µg/hr/7 days or vehicle via a cannula attached to an osmotic mini-pump. Real-time RT-PCR was performed with specific primers against the TRPA1 or CGRP sequences, and the data were normalized to the mRNA levels found in the contralateral (right) ganglion for each rat/group. Data are presented as mean ± SEM (n = 4, * = p < 0.05 vs. vehicle group; two-tailed paired t test).

NGF Alters the Expression Pattern of TRPA1 in Trigeminal Ganglia Neurons
Since TRPA1 is expressed exclusively within a subset of TRPV1-positive sensory neurons representing a major subclass of nociceptors in the sensory ganglia (Story et al., 2003), we examined alterations in TRPA1 expression patterns by using TRPV1 as a marker. The use of combined in situ hybridization (for TRPA1) and immunohistochemistry (for TRPV1) demonstrated that systemic administration of NGF increased the proportion of TRPA1-positive neurons within the TRPV1 population, which in turn was also up-regulated by NGF treatment (see Table). Thus, quantitative cell counts by blinded observers (Table) indicated that NGF treatment significantly expanded the percentage of TRPV1-positive neurons that were also positive for TRPA1 mRNA from 49.3% ± 2.04% of TRPV1 neurons to 85.4% ± 4.2% of TRPV1 neurons (p < 0.001). Representative images of trigeminal ganglia sections from vehicle- and NGF-treated rats are presented in Fig. 2.

View larger version (51K): [in this window] [in a new window]   Figure 2. Systemic NGF increases the expression of TRPA1 in the TRPV1-positive subset of trigeminal ganglia neurons. In situ hybridization against the TRPA1 mRNA, combined with immunohistochemistry against the TRPV1 protein, was performed in trigeminal ganglia cryo-sections (20 µm in thickness) from rats injected with saline or NGF. TRPA1 mRNA (Panel A) was co-localized with TRPV1-containing neurons (B) in the trigeminal ganglia of vehicle (saline)-injected rats. The co-localization of TRPA1 mRNA (C) and TRPV1 (D) was significantly increased in the trigeminal ganglia of NGF-injected rats. Vertical white arrows show representative cells that contain detectable levels of TRPV1 but not of TRPA1 mRNA. Horizontal yellow arrows show cells that contain detectable levels of both TRPA1 and TRPV1. (E,F) Double-immunohistochemistry against TRPA1 and TRPV1 was performed in trigeminal ganglia neurons cultured in the presence of NGF or vehicle for 72 hrs. Immunoreactive TRPA1 protein was co-localized with TRPV1 in vehicle-treated trigeminal ganglia neurons (E). The co-localization of TRPA1 protein and TRPV1 was significantly increased in NGF-treated trigeminal ganglia neurons (F). Vertical white arrows show representative cells that contain detectable levels of TRPV1 but not of TRPA1. Horizontal yellow arrows show cells that contains detectable levels of both TRPA1 and TRPV1.

View larger version (13K): [in this window] [in a new window]   Figure 3. NGF treatment leads to an increase of TRPA1 activity measured as mustard-oil-evoked inward currents (IMO) in whole-cell patch clamp configuration. (A) The exposure of cultured trigeminal ganglia neurons to NGF (100 ng/mL) time-dependently increased the peak of IMO (black line) as compared with vehicle-treated neurons (grey line). Trigeminal ganglia neurons were grown in culture for a total of 72 hrs in the presence of NGF (100 ng/mL) or vehicle. IMO was recorded at 8, 24, 48, and 72 hrs of trigeminal ganglia culture. Data are presented as mean ± SEM (n = 8–16, *** = p < 0.001 for time 8 hrs vs. 24, 48, 72 hrs within each treatment group, and a = p < 0.01 NGF- vs. NGF+ for each time-point; two-way ANOVA with Bonferroni’s post hoc test). (B,C) Representative traces of IMO in trigeminal ganglia neurons grown in culture in the presence of vehicle (NGF–) or NGF+ for 8 hrs (top trace) and 48 hrs (bottom trace). Mustard oil (50 µM) was locally applied to trigeminal ganglia neurons for 60 sec.

	DISCUSSION

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Previous studies have reported that NGF up-regulates CGRP in TrkA-containing sensory neurons (Inaishi et al., 1992; Amann et al., 1996), and therefore the demonstration of a significant increase in CGRP mRNA serves as a positive control for selection of a biologically sufficient dosage and time for NGF-induced gene transcription. To confirm TRPA1 up-regulation by NGF in cultured trigeminal ganglia neurons, we delivered NGF to the intact animal and analyzed the expression of TRPA1 transcripts in the trigeminal ganglia. This set of experiments demonstrated that the local intraganglionic infusion of NGF produced a response qualitatively similar to that of the s.c. injection of NGF, and, moreover, was greater in the ipsilateral vs. contralateral ganglia, indicating that the effect of NGF on TRPA1 expression was not due to some systemic mechanism, such as an endocrine response. In addition, cells such as mast cells (Leon et al., 1994), fibroblasts (Manni et al., 2003), and microglia (Heese et al., 1998) are known to release NGF upon inflammatory injury. Thus, levels of NGF increase five- to eight-fold after exposure of rat molar dental pulp (Wheeler et al., 1998) and inflammation of the temporomandibular joint (Spears et al., 2005). These local changes in NGF expression are thought to contribute to hyperalgesia (Lewin and Mendell, 1993) and to altered transcription of genes such as CGRP and TRPV1 (Price et al., 2005). Therefore, our in vivo experiments demonstrating that NGF up-regulates TRPA1 may have considerable significance in the understanding of neurotrophin regulation of orofacial pain and inflammation. It could also be noted that the increase in TRPA1 mRNA, and subsequent protein expression, was primarily observed in a population of TRPV1-expressing trigeminal ganglia neurons, which constitutes a major subclass of nociceptors (Caterina et al., 1999). Collectively, these results indicate that NGF dynamically alters the receptor expression pattern of capsaicin-sensitive trigeminal ganglia nociceptors.

In the electrophysiology experiments, we evaluated whether the in vitro concentration of NGF (100 ng/mL), which evoked the greatest increase in TRPA1 mRNA, could lead to increased functional activities of this channel. We used mustard oil, a selective TRPA1 agonist, to evaluate the peak current achieved at different time-points of NGF treatment. Indeed, NGF time-dependently increased the peak of I_MO. This increased current could not possibly be due to acute NGF effects, since it was withdrawn from the cultures 1–2 hrs prior to the recordings. Analysis of these data suggests that the up-regulated TRPA1 mRNA led to de novo protein synthesis and the assembly of functional TRPA1 channels in the plasma membrane of the trigeminal ganglia sensory neurons.

NGF has been found to up-regulate the expression of TRPA1 in DRG neurons via a p38MAPK pathway, leading to the development of cold hyperalgesia (Obata et al., 2005). These findings have important implications, since the levels of NGF and its receptors are known to be increased in pain-sensing fibers following nerve injury and inflammation (Sebert and Shooter, 1993; Wheeler et al., 1998; Sullins et al., 2000). In addition, the results of this study support recent evidence that trigeminal sensory neurons express TRPA1 in TRPV1-containing neurons, including primary afferent neurons in the rat dental pulp (Park et al., 2006). This increased NGF responsiveness could possibly contribute to cold hyperalgesia (Katsura et al., 2006) in orofacial pain conditions such as irreversible pulpitis. Interestingly, recent studies with mice carrying the deletion of the TRPA1 gene (TRPA1–/–) have shown conflicting results regarding the involvement of TRPA1 in the detection of noxious cold (Bautista et al., 2006; Kwan et al., 2006). However, the role of TRPA1 in the generation of cold hyperalgesia after nerve injury or chronic inflammation has not been evaluated in the TRPA1–/– mice. These reports could suggest that TRPA1 may be involved in the development of cold hyperalgesia only following nerve injury or inflammation, but not in the detection of noxious cold in uninjured animals (Obata et al., 2005).

Persons suffering from trigeminal neuralgia and vascular orofacial pain complain about cold hyperalgesia (Steranka et al., 1988; Eide and Rabben, 1998). Moreover, a pronounced hyperalgesia to cold stimulus (in either magnitude or duration of pain) is a cardinal sign in the diagnosis of irreversible pulpitis (Selden, 2000). TRPA1 could be involved in the detection of cold hyperalgesia in persons with chronic pulpal inflammation or nerve injury. Indeed, in a model of trigeminal nerve injury, cold hyperalgesia appears to be a pronounced symptom (Chichorro et al., 2006). TRPA1 is also crucial for the acute thermal hyperalgesia induced by bradykinin (Bautista et al., 2006), a major inflammatory mediator, which has been shown to activate and sensitize nociceptors in many models of pain (Steranka et al., 1988; Wang et al., 2006), including a model of orofacial pain (Chichorro et al., 2004).

Collectively, these results demonstrate for the first time that NGF evokes the functional up-regulation of the TRPA1 channel in trigeminal ganglia neurons. These findings have significant implications, since the elevated expression of TRPA1 could lead to enhanced hyperalgesia—in particular, cold hyperalgesia and bradykinin-induced acute thermal hyperalgesia—in the orofacial region.

	ACKNOWLEDGMENTS

 
We thank Dr. Michael Henry for his excellent advice. We also thank Gabriela Helesic and Griffin Perry for their technical assistance. This work has been supported by NIDA grant RO1-DA19585.

Received for publication May 9, 2006. Revision received January 18, 2007. Accepted for publication January 20, 2007.

	REFERENCES

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

 

• Amann R, Sirinathsinghji DJ, Donnerer J, Liebmann I, Schuligoi R (1996). Stimulation by nerve growth factor of neuropeptide synthesis in the adult rat in vivo: bilateral response to unilateral intraplantar injections. Neurosci Lett 203:171–174.[CrossRef][Medline] [Order article via Infotrieve]
• Bandell M, Story GM, Hwang SW, Viswanath V, Eid SR, Petrus MJ, et al. (2004). Noxious cold ion channel TRPA1 is activated by pungent compounds and bradykinin. Neuron 41:849–857.[CrossRef][Medline] [Order article via Infotrieve]
• Bautista DM, Movahed P, Hinman A, Axelsson HE, Sterner O, Hogestatt ED, et al. (2005). Pungent products from garlic activate the sensory ion channel TRPA1. Proc Natl Acad Sci USA 102:12248–12252.[Abstract/Free Full Text]
• Bautista DM, Jordt SE, Nikai T, Tsuruda PR, Read AJ, Poblete J, et al. (2006). TRPA1 mediates the inflammatory actions of environmental irritants and proalgesic agents. Cell 124:1269–1282.[CrossRef][Medline] [Order article via Infotrieve]
• Bowles WR, Sabino M, Harding-Rose C, Hargreaves KM (2004). Nerve growth factor treatment enhances release of immunoreactive calcitonin gene-related peptide but not substance P from spinal dorsal horn slices in rats. Neurosci Lett 363:239–242.[CrossRef][Medline] [Order article via Infotrieve]
• Caterina MJ, Rosen TA, Tominaga M, Brake AJ, Julius D (1999). A capsaicin-receptor homologue with a high threshold for noxious heat. Nature 398:436–441.[CrossRef][Medline] [Order article via Infotrieve]
• Chichorro JG, Lorenzetti BB, Zampronio AR (2004). Involvement of bradykinin, cytokines, sympathetic amines and prostaglandins in formalin-induced orofacial nociception in rats. Br J Pharmacol 141:1175–1184.
• Chichorro JG, Zampronio AR, Souza GE, Rae GA (2006). Orofacial cold hyperalgesia due to infraorbital nerve constriction injury in rats: reversal by endothelin receptor antagonists but not non-steroidal anti-inflammatory drugs. Pain 123:64–74.[Medline] [Order article via Infotrieve]
• Chomczynski P, Sacchi N (1987). Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem 162:156–159.[Medline] [Order article via Infotrieve]
• Diogenes A, Patwardhan AM, Jeske NA, Ruparel NB, Goffin V, Akopian AN, et al. (2006). Prolactin modulates TRPV1 in female rat trigeminal sensory neurons. J Neurosci 26:8126–8136.[Abstract/Free Full Text]
• Eide PK, Rabben T (1998). Trigeminal neuropathic pain: pathophysiological mechanisms examined by quantitative assessment of abnormal pain and sensory perception. Neurosurgery 43:1103–1110.[CrossRef][Medline] [Order article via Infotrieve]
• Heese K, Hock C, Otten U (1998). Inflammatory signals induce neurotrophin expression in human microglial cells. J Neurochem 70:699–707.[Medline] [Order article via Infotrieve]
• Hille B (2001). Ion channels of excitable membranes. 3rd ed. Sunderland, MA: Sinauer Associates Inc.
• Inaishi Y, Kashihara Y, Sakaguchi M, Nawa H, Kuno M (1992). Cooperative regulation of calcitonin gene-related peptide levels in rat sensory neurons via their central and peripheral processes. J Neurosci 12:518–524.[Abstract]
• Jeske NA, Patwardhan AM, Gamper N, Price TJ, Akopian AN, Hargreaves KM (2006). Cannabinoid WIN 55,212–2 regulates TRPV1 phosphorylation in sensory neurons. J Biol Chem 281:32879–32890.[Abstract/Free Full Text]
• Jordt SE, Bautista DM, Chuang HH, McKemy DD, Zygmunt PM, Hogestatt ED, et al. (2004). Mustard oils and cannabinoids excite sensory nerve fibres through the TRP channel ANKTM1. Nature 427:260–265.[CrossRef][Medline] [Order article via Infotrieve]
• Katsura H, Obata K, Mizushima T, Yamanaka H, Kobayashi K, Dai Y, et al. (2006). Antisense knock down of TRPA1, but not TRPM8, alleviates cold hyperalgesia after spinal nerve ligation in rats. Exp Neurol 200:112–123.[Medline] [Order article via Infotrieve]
• Kwan KY, Allchorne AJ, Vollrath MA, Christensen AP, Zhang DS, Woolf CJ, et al. (2006). TRPA1 contributes to cold, mechanical, and chemical nociception but is not essential for hair-cell transduction. Neuron 50:277–289.[CrossRef][Medline] [Order article via Infotrieve]
• Leon A, Buriani A, Dal Toso R, Fabris M, Romanello S, Aloe L, et al. (1994). Mast cells synthesize, store, and release nerve growth factor. Proc Natl Acad Sci USA 91:3739–3743.[Abstract/Free Full Text]
• Lewin GR, Mendell LM (1993). Nerve growth factor and nociception. Trends Neurosci 16:353–359.[CrossRef][Medline] [Order article via Infotrieve]
• Manni L, Lundeberg T, Fiorito S, Bonini S, Vigneti E, Aloe L (2003). Nerve growth factor release by human synovial fibroblasts prior to and following exposure to tumor necrosis factor-alpha, interleukin-1 beta and cholecystokinin-8: the possible role of NGF in the inflammatory response. Clin Exp Rheumatol 21:617–624.[Medline] [Order article via Infotrieve]
• Obata K, Katsura H, Mizushima T, Yamanaka H, Kobayashi K, Dai Y, et al. (2005). TRPA1 induced in sensory neurons contributes to cold hyperalgesia after inflammation and nerve injury. J Clin Invest 115:2393–2401.[CrossRef][Medline] [Order article via Infotrieve]
• Park CK, Kim MS, Fang Z, Li HY, Jung SJ, Choi SY, et al. (2006). Functional expression of thermo-transient receptor potential channels in dental primary afferent neurons: implication for tooth pain. J Biol Chem 281:17304–17311.[Abstract/Free Full Text]
• Patwardhan AM, Berg KA, Akopain AN, Jeske NA, Gamper N, Clarke WP, et al. (2005). Bradykinin-induced functional competence and trafficking of the delta-opioid receptor in trigeminal nociceptors. J Neurosci 25:8825–8832.[Abstract/Free Full Text]
• Patwardhan AM, Jeske NA, Price TJ, Gamper N, Akopian AN, Hargreaves KM (2006). The cannabinoid WIN 55,212–2 inhibits transient receptor potential vanilloid 1 (TRPV1) and evokes peripheral antihyperalgesia via calcineurin. Proc Natl Acad Sci USA 103:11393–11398.[Abstract/Free Full Text]
• Price TJ, Louria MD, Candelario-Soto D, Dussor GO, Jeske NA, Patwardhan AM, et al. (2005). Treatment of trigeminal ganglion neurons in vitro with NGF, GDNF or BDNF: effects on neuronal survival, neurochemical properties and TRPV1-mediated neuropeptide secretion. BMC Neurosci 6:4.[CrossRef][Medline] [Order article via Infotrieve]
• Schneider JS, Denaro FJ, Olazabal UE, Leard HO (1981). Stereotaxic atlas of the trigeminal ganglion in rat, cat, and monkey. Brain Res Bull 7:93–95.[CrossRef][Medline] [Order article via Infotrieve]
• Sebert ME, Shooter EM (1993). Expression of mRNA for neurotrophic factors and their receptors in the rat dorsal root ganglion and sciatic nerve following nerve injury. J Neurosci Res 36:357–367.[CrossRef][Medline] [Order article via Infotrieve]
• Selden HS (2000). Diagnostic thermal pulp testing: a technique. J Endod 26:623–624.[Medline] [Order article via Infotrieve]
• Shu XQ, Mendell LM (1999). Neurotrophins and hyperalgesia. Proc Natl Acad Sci USA 96:7693–7696.[Abstract/Free Full Text]
• Skoff AM, Adler JE (2006). Nerve growth factor regulates substance P in adult sensory neurons through both TrkA and p75 receptors. Exp Neurol 197:430–436.[CrossRef][Medline] [Order article via Infotrieve]
• Spears R, Dees LA, Sapozhnikov M, Bellinger LL, Hutchins B (2005). Temporal changes in inflammatory mediator concentrations in an adjuvant model of temporomandibular joint inflammation. J Orofac Pain 19:34–40.[Medline] [Order article via Infotrieve]
• Steranka LR, Manning DC, DeHaas CJ, Ferkany JW, Borosky SA, Connor JR, et al. (1988). Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions. Proc Natl Acad Sci USA 85:3245–3249.[Abstract/Free Full Text]
• Story GM, Peier AM, Reeve AJ, Eid SR, Mosbacher J, Hricik TR, et al. (2003). ANKTM1, a TRP-like channel expressed in nociceptive neurons, is activated by cold temperatures. Cell 112:819–829.[CrossRef][Medline] [Order article via Infotrieve]
• Sullins JS, Carnes DL Jr, Kaldestad RN, Wheeler EF (2000). Time course of the increase in trk A expression in trigeminal neurons after tooth injury. J Endod 26:88–91.[CrossRef][Medline] [Order article via Infotrieve]
• Wang H, Ehnert C, Brenner GJ, Woolf CJ (2006). Bradykinin and peripheral sensitization. Biol Chem 387:11–14.[CrossRef][Medline] [Order article via Infotrieve]
• Wheeler EF, Naftel JP, Pan M, von Bartheld CS, Byers MR (1998). Neurotrophin receptor expression is induced in a subpopulation of trigeminal neurons that label by retrograde transport of NGF or fluoro-gold following tooth injury. Brain Res Mol Brain Res 61:23–38.[Medline] [Order article via Infotrieve]

Journal of Dental Research, Vol. 86, No. 6, 550-555 (2007)
DOI: 10.1177/154405910708600612


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