Transient Receptor Potential Vanilloid Type 1 Expression Research Articles

Botulinum toxin type A reduces TRPV1 expression in the dorsal root ganglion in rats with adjuvant-arthritis pain

Arthritis pain affects people's long-term health, and recent studies have demonstrated that transient receptor potential vanilloid type 1 (TRPV1) plays a crucial role in arthritis pain. In addition, Pre-clinical evidence indicated that botulinum toxin type A (BoNT/A) has antinociceptive effect. The present study investigated the causality between the antinociceptive effects of BoNT/A and the expression of TRPV1 in dorsal root ganglion (DRG) in rats with adjuvant-arthritis pain. The results showed that BoNT/A significantly reduced adjuvant-arthritis nociceptive behaviors in a dose-dependent manner. Furthermore, the BoNT/A cleaved synaptosomal-associated protein of 25 kDa (cl-SNAP-25) was detected in the DRG using immunofluorescence after intra-articular administration. Although BoNT/A significantly reduced the protein levels of TRPV1, there were no significant changes in the mRNA levels of TRPV1 between CFA and BoNT/A (1U, 3U, 10U) group after BoNT/A retrograde axonal transport into the DRG with quantitative RT-PCR. This research provides evidence that the antinociceptive mechanism of BoNT/A might be mediated by reduction of TRPV1 expression through inhibition of its plasma membrane trafficking after intra-articular administration.

Hypolipidaemic effect and mechanism of paprika seed oil on Sprague-Dawley rats.

Details regarding the functional properties of paprika seed oil are relatively scarce. In this study the hypolipidaemic effects and mechanisms of paprika seed oil on Sprague-Dawley rats are explored, which may improve the usage of paprika seed source and provide a theoretical basis of paprika seed oil for the alleviation of hyperlipidaemia. In capsaicin and paprika seed oil (PSO) groups, total cholesterol (TC) and total triglyceride (TG) in serum and liver lipids of rats were significantly decreased (P < 0.05). The contents of serum HDL cholesterol were increased and the contents of serum LDL cholesterol were decreased (P < 0.05). Real-time PCR analyses revealed that the hepatic mRNA expression of fatty acid synthetase (FAS) is decreased and the expression levels of HSL is increased (P < 0.05). The mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) is decreased and the expression levels of low-density lipoprotein receptor (LDLR) is significantly improved (P < 0.05). The cholesterol 7-hydroxylase (CYP7A1) expression is regulated to control the cholesterol-to-bile acid transformation and cholesterol excretion is promoted. Capsaicin and unsaturated fatty acid PSO can activate and improve the mRNA expression of transient receptor potential vanilloid type-1 (TRPV1) and peroxisome proliferators-activated receptors (PPARα). The hypolipidaemic effects of paprika seed oil (PSO) may be attributed to the inhibition of lipid synthesis via suppressing the expression of HMG-CoAR, CYP7A1 and FAS, meanwhile, promoting the metabolism and excretion of lipids via up-regulating the expression of LDLR, HSL, TRPV1 and PPARα. © 2017 Society of Chemical Industry.

Elevated expression of transient receptor potential vanilloid type1 in dorsal root ganglia of rats with endometriosis.

Pain is the most pronounced complaint of women with endometriosis, however the underlying mechanism is still poorly understood. In the present study, the authors evaluate the effect of transient receptor potential vanilloid type 1 (TRPV1) of dorsal root ganglia (DRG) on endometriosis-associated pain. A total of 36 SD rats were randomly divided into a sham group (n=9) and a Model group (n=27), accepted auto-transplanted pieces of fat or uterus to the pelvic cavity. At 4 weeks, the Model group was randomly subdivided into the following groups: ENDO group (no treatment, n=9), BCTC group (Model + BCTC, an antagonist of TRPV1, n=9), Vehicle group (Model + cyclodextrin, the vehicle of BCTC, n=9). Tail-flick test was performed prior to surgery, 1 h prior to and following treatment of BCTC or cyclodextrin. The expression of TRPV1, substance P (SP), calcitonin gene-related peptide (CGRP) in L1-L6 DRG was measured via immunohistochemistry, western blotting and RT-qPCR. The results indicated that the Model group exhibited a significant decrease in tail flick latency compared to pre-surgical baseline, and the expression of TRPV1, SP, CGRP protein and mRNA in L1-L6 DRG significantly increased compared to the sham group. BCTC significantly improved tail flick latency, and downregulated the expression of TRPV1, SP and CGRP protein and mRNA levels in L1-L6 DRG compared to ENDO group. However, there were no significant differences of those in Vehicle group compared with the ENDO group. Taken together, the current study provides evidence that TRPV1 expressed in DRG may serve an important role in endometriosis-associated pain.

Antinociceptive Effect of Ghrelin in a Rat Model of Irritable Bowel Syndrome Involves TRPV1/Opioid Systems

Background/Aims: Irritable bowel syndrome (IBS), defined as recurrent abdominal pain and changes in bowel habits, seriously affects quality of life and ability to work. Ghrelin is a brain-gut hormone, which has been reported to show antinociceptive effects in peripheral pain. We investigated the effect of ghrelin on visceral hypersensitivity and pain in a rat model of IBS. Methods: Maternal deprivation (MD) was used to provide a stress-induced model of IBS in Wistar rats. Colorectal distension (CRD) was used to detect visceral sensitivity, which was evaluated by abdominal withdrawal reflex (AWR) scores. Rats that were confirmed to have visceral hypersensitivity after MD were injected with ghrelin (10 µg/kg) subcutaneously twice a week from weeks 7 to 8. [D-Lys3]-GHRP-6 (100 nmol/L) and naloxone (100 nmol/L) were administered subcutaneously to block growth hormone secretagogue receptor 1α (GHS-R1α) and opioid receptors, respectively. Expression of transient receptor potential vanilloid type 1 (TRPV1) and µ and κ opioid receptors (MOR and KOR) in colon, dorsal root ganglion (DRG) and cerebral cortex tissues were detected by western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemical analyses and immunofluorescence. Results: Ghrelin treatment increased expression of opioid receptors and inhibited expression of TRPV1 in colon, dorsal root ganglion (DRG) and cerebral cortex. The antinociceptive effect of ghrelin in the rat model of IBS was partly blocked by both the ghrelin antagonist [D-Lys3]-GHRP-6 and the opioid receptor antagonist naloxone. Conclusion: The results indicate that ghrelin exerted an antinociceptive effect, which was mediated via TRPV1/opioid systems, in IBS-induced visceral hypersensitivity. Ghrelin might potentially be used as a new treatment for IBS.

Sex-dependent expression of TRPV1 in bladder arterioles.

Transient receptor potential vanilloid type 1 (TRPV1) is a major nociceptive ion channel implicated in bladder physiology and/or pathophysiology. However, the precise expression of TRPV1 in neuronal vs. nonneuronal bladder cells is uncertain. Here we used reporter mouse lines (TRPV1-Cre:tdTomato and TRPV1PLAP-nlacZ) to map expression of TRPV1 in postnatal bladder. TRPV1 was not detected in the urothelium, however, we found marked expression of TRPV1 lineage in sensory nerves, and surprisingly, in arterial/arteriolar smooth muscle (ASM) cells. Tomato fluorescence was prominent in the vesical arteries and in small-diameter (15-40 μm) arterioles located in the suburothelial layer with a near equal distribution in bladder dome and base. Notably, arteriolar TRPV1 expression was greater in females than in males and increased in both sexes after 90 days of age, suggesting sex hormone and age dependency. Analysis of whole bladder and vesical artery TRPV1 mRNA revealed a similar sex and developmental dependence. Pharmacological experiments confirmed functional TRPV1 protein expression; capsaicin increased intracellular Ca2+ in ∼15% of ASM cells from wild-type female bladders, but we observed no responses to capsaicin in bladder arterioles isolated from TRPV1-null mice. Furthermore, capsaicin triggered arteriole constriction that was rapidly reversed by the TRPV1 antagonist, BCTC. These data show that predominantly in postpubertal female mice, bladder ASM cells express functional TRPV1 channels that may act to constrict arterioles. TRPV1 may therefore play an important role in regulating the microcirculation of the female bladder, and this effect may be of significance during inflammatory conditions.

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

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.

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

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 Ca2+ influx via TRPV1 channels, which leads to mitochondrial Ca2+ 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 Ca2+ signals, mitochondrial Ca2+ accumulation and Na+- and Ca2+-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.

Upregulation of Transient Receptor Potential Vanilloid Type-1 Channel Activity and Ca2+ Influx Dysfunction in Human Pterygial Cells.

The heat-sensitive transient receptor potential vanilloid type-1 (TRPV1) channel (i.e., capsaicin [CAP] receptor) is upregulated in numerous cancers. This study determined if this response occurs in fresh and cultured hyperplastic human pterygial epithelial tissues. Reverse transcriptase PCR and quantitative real-time PCR, along with immunohistochemistry and Western blotting, characterized TRPV1 expression patterns in pterygial and healthy conjunctival tissue, primary and immortalized pterygial cells (hPtEC), and primary and immortalized conjunctival epithelial cells (HCjEC). Imaging of Ca2+ and planar whole-cell patch-clamping evaluated TRP channel activity. An MTS assay measured cell metabolic activity and a cell growth assay monitored proliferation. Capsaicin (20 μM) and elevating bath temperature above 43°C activated Ca2+ transients more in hPtEC than HCjEC. Capsaicin induced corresponding changes in inward currents that were inhibited by 20 μM capsazepine (CPZ). Vascular endothelial growth factor (VEGF) also increased Ca2+-influx and induced corresponding inward currents more in hPtEC than in HCjEC, whereas CPZ (20 μM), BCTC (20 μM), or La3+ (500 μM) reduced these responses, respectively. Whereas epidermal growth factor (EGF) increased proliferation more in hPtEC than in HCjEC, VEGF had no effect on this response. Capsazepine suppressed hPtEC proliferation induced by EGF and VEGF, whereas it was cytotoxic to HCjEC. Mitogenic responses to EGF and VEGF are mediated through TRPV1 transactivation. Only in hPtEC do the increases in proliferation induced by EGF exceed those in HCjEC. Therefore, TRPV1 is a potential drug target whose clinical relevance in treating pterygium warrants further assessment.

Contribution of sensory nerves to LPS-induced hyperresponsiveness of human isolated bronchi

Bacterial lipopolysaccharide (LPS) can induce bronchial hyperresponsiveness (BHR), but the underlying mechanisms remain to be determined. Here, the possible contribution of sensory nerves to LPS-induced BHR was examined in human isolated bronchi to pharmacologically identify the mechanisms underlying this phenomenon. Human isolated bronchial tone was induced by electrical field stimulation (EFS). The responses of airways to LPS, with or without capsaicin desensitization or thiorphan treatment were studied and the transient receptor potential vanilloid type 1 (TRPV1) expression was assessed. We performed similar experiments in the presence of a TRPV1 or a neurokinin (NK) 2 receptor antagonist using SB366791 and GR159897, respectively. LPS increased (≃2.3-fold, P<0.001) the contraction induced by EFS, compared to control tissues. Acute administration of capsaicin enhanced (≃2.3-fold, P<0.001) the EFS-mediated contraction, but did not potentiate the effect of LPS. Thiorphan increased (≃1.3-fold, P<0.05) the contractile response of LPS treated tissues and, at lower frequencies, it enhanced (≃1.7-fold, P<0.001) the capsaicin-induced contraction. In capsaicin-desensitized bronchi, LPS did not modify (P>0.05) the EFS contractile response, nor after treatment with thiorphan. Capsaicin desensitization reduced (≃0.4-fold, P<0.001) the LPS-induced BHR. SB366791 and GR159897 prevented the LPS-induced BHR and the release of NKA. LPS increased (+85.3±9.5%, P<0.01) the surface membrane expression of TRPV1 in parasympathetic ganglia. Our results demonstrate the involvement of capsaicin-sensitive sensory nerves and neutral endopeptidases in LPS-induced BHR of the human bronchi, associated with an upregulation of TRPV1 and release of NKA.

Prostaglandin E2 inhibits the proinflammatory phenotype induced by TGF-β on monocyte-derived dendritic cells

Prostaglandin E2 inhibits the proinflammatory phenotype induced by TGF-β on monocyte-derived dendritic cells

Decreased miR-199 augments visceral pain in patients with IBS through translational upregulation of TRPV1

ObjectiveMany patients with irritable bowel syndrome IBS not only have abdominal pain but also may suffer from visceral hypersensitivity and heighted visceral nociception. Moreover, IBS has few effective therapeutic agents...

Cross-talk between alpha1D-adrenoceptors and transient receptor potential vanilloid type 1 triggers prostate cancer cell proliferation.

BackgroundThere is evidence that calcium (Ca2+) increases the proliferation of human advanced prostate cancer (PCa) cells but the ion channels involved are not fully understood. Here, we investigated the correlation between alpha1D-adrenergic receptor (alpha1D-AR) and the transient receptor potential vanilloid type 1 (TRPV1) expression levels in human PCa tissues and evaluated the ability of alpha1D-AR to cross-talk with TRPV1 in PCa cell lines.MethodsThe expression of alpha1D-AR and TRPV1 was examined in human PCa tissues by quantitative RT-PCR and in PCa cell lines (DU145, PC3 and LNCaP) by cytofluorimetry. Moreover, alpha1D-AR and TRPV1 colocalization was investigated by confocal microscopy in PCa cell lines and by fluorescence microscopy in benign prostate hyperplasia (BPH) and PCa tissues. Cell proliferation was assessed by BrdU incorporation. Alpha1D-AR/TRPV1 knockdown was obtained using siRNA transfection. Signalling pathways were evaluated by measurement of extracellular acidification rate, Ca2+ flux, IP3 production, western blot and MTT assay.ResultsThe levels of the alpha1D-AR and TRPV1 mRNAs are increased in PCa compared to BPH specimens and a high correlation between alpha1D-AR and TRPV1 expression levels was found. Moreover, alpha1D-AR and TRPV1 are co-expressed in prostate cancer cell lines and specimens. Noradrenaline (NA) induced an alpha1D-AR- and TRPV1-dependent protons release and Ca2+ flux in PC3 cell lines; NA by triggering the activation of phospholipase C (PLC), protein kinase C (PKC) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways stimulated PC3 cell proliferation, that was completely inhibited by clopenphendioxan (WS433) and capsazepine (CPZ) combination or by alpha1D-AR/TRPV1 double knockdown.ConclusionsWe demonstrate a cross-talk between alpha1D-AR and TRPV1, that is involved in the control of PC3 cell proliferation. These data strongly support for a putative novel pharmacological approach in the treatment of PCa by targeting both alpha1D-AR and TRPV1 channels.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-921) contains supplementary material, which is available to authorized users.

Palmitoylethanolamide, a naturally occurring lipid, is an orally effective intestinal anti-inflammatory agent.

Palmitoylethanolamide (PEA) acts via several targets, including cannabinoid CB1 and CB2 receptors, transient receptor potential vanilloid type-1 (TRPV1) ion channels, peroxisome proliferator-activated receptor alpha (PPAR α) and orphan G protein-coupled receptor 55 (GRR55), all involved in the control of intestinal inflammation. Here, we investigated the effect of PEA in a murine model of colitis. Colitis was induced in mice by intracolonic administration of dinitrobenzenesulfonic acid (DNBS). Inflammation was assessed by evaluating inflammatory markers/parameters and by histology; intestinal permeability by a fluorescent method; colonic cell proliferation by immunohistochemistry; PEA and endocannabinoid levels by liquid chromatography mass spectrometry; receptor and enzyme mRNA expression by quantitative RT-PCR. DNBS administration caused inflammatory damage, increased colonic levels of PEA and endocannabinoids, down-regulation of mRNA for TRPV1 and GPR55 but no changes in mRNA for CB1 , CB2 and PPARα. Exogenous PEA (i.p. and/or p.o., 1 mg·kg(-1) ) attenuated inflammation and intestinal permeability, stimulated colonic cell proliferation, and increased colonic TRPV1 and CB1 receptor expression. The anti-inflammatory effect of PEA was attenuated or abolished by CB2 receptor, GPR55 or PPARα antagonists and further increased by the TRPV1 antagonist capsazepine. PEA improves murine experimental colitis, the effect being mediated by CB2 receptors, GPR55 and PPARα, and modulated by TRPV1 channels.

Perineural pretreatment of bee venom attenuated the development of allodynia in the spinal nerve ligation injured neuropathic pain model; an experimental study.

BackgroundDiluted bee venom (BV) is known to have anti-nociceptive and anti-inflammatory effects. We therefore assessed whether perineural bee venom pretreatment could attenuate the development of neuropathic pain in the spinal nerve ligation injured animal model.MethodsNeuropathic pain was surgically induced in 30 male Sprague Dawley rats by ligation of the L5 and L6 spinal nerves, with 10 rats each treated with saline and 0.05 and 0.1 mg BV. Behavioral testing for mechanical, cold, and thermal allodynia was conducted on postoperative days 3 to 29. Three rats in each group and 9 sham operated rats were sacrificed on day 9, and the expression of transient receptor potential vanilloid type 1 (TRPV1), ankyrin type 1 (TRPA1), and melastatin type 8 (TRPM8) receptors in the ipsilateral L5 dorsal root ganglion was analyzed.ResultsThe perineural administration of BV to the spinal nerves attenuated the development of mechanical, thermal, and cold allodynia, and the BV pretreatment reduced the expression of TRPV1, TRPA1, TRPM8 and c − Fos in the ipsilateral dorsal root ganglion.ConclusionThe current study demonstrates that the perineural pretreatment with diluted bee venom before the induction of spinal nerve ligation significantly suppresses the development of neuropathic pain. Furthermore, this bee venom induced suppression was strongly related with the involvement of transient receptor potential family members.

Molecular basis for the improvement in muscle metaboreflex and mechanoreflex control in exercise-trained humans with chronic heart failure.

Previous studies have demonstrated that muscle mechanoreflex and metaboreflex controls are altered in heart failure (HF), which seems to be due to changes in cyclooxygenase (COX) pathway and changes in receptors on afferent neurons, including transient receptor potential vanilloid type-1 (TRPV1) and cannabinoid receptor type-1 (CB1). The purpose of the present study was to test the hypotheses: 1) exercise training (ET) alters the muscle metaboreflex and mechanoreflex control of muscle sympathetic nerve activity (MSNA) in HF patients. 2) The alteration in metaboreflex control is accompanied by increased expression of TRPV1 and CB1 receptors in skeletal muscle. 3) The alteration in mechanoreflex control is accompanied by COX-2 pathway in skeletal muscle. Thirty-four consecutive HF patients with ejection fractions <40% were randomized to untrained (n = 17; 54 ± 2 yr) or exercise-trained (n = 17; 56 ± 2 yr) groups. MSNA was recorded by microneurography. Mechanoreceptors were activated by passive exercise and metaboreceptors by postexercise circulatory arrest (PECA). COX-2 pathway, TRPV1, and CB1 receptors were measured in muscle biopsies. Following ET, resting MSNA was decreased compared with untrained group. During PECA (metaboreflex), MSNA responses were increased, which was accompanied by the expression of TRPV1 and CB1 receptors. During passive exercise (mechanoreflex), MSNA responses were decreased, which was accompanied by decreased expression of COX-2, prostaglandin-E2 receptor-4, and thromboxane-A2 receptor and by decreased in muscle inflammation, as indicated by increased miRNA-146 levels and the stable NF-κB/IκB-α ratio. In conclusion, ET alters muscle metaboreflex and mechanoreflex control of MSNA in HF patients. This alteration with ET is accompanied by alteration in TRPV1 and CB1 expression and COX-2 pathway and inflammation in skeletal muscle.

Abstract 453: Ablation of TRPV1 Impairs Exendin-4 Induced Suppression in Renal Cytokine Release

Impairment of function and expression of the transient receptor potential vanilloid type 1 (TRPV1) occurs in obesity and diabetes, which may aggravate inflammation and tissue injury given that the TRPV1 mediated pathway has been shown to be anti-inflammatory. Glucagon-like peptide-1 (GLP-1), an incretin hormone released in response to food intake, is capable of protecting tissues from injury, but its mechanism largely unknown. We tested the hypothesis that exendin-4 (Ex4), a GLP-1 receptor agonist, suppresses hypoxia-induced cytokine release via a TRPV1 mediated pathway. Using gene-targeted TRPV1-null mutant (TRPV1 -/- ) or wild-type (WT, C57BL/6) mice, plasma creatinine or urine lactate dehydrogenase (LDH) levels were measured 40- min after ischemia plus 3-hr reperfusion (I/R). Renal I/R increased plasma creatinine and urine LDH levels with a greater magnitude in TRPV1-/- than WT mice (creatinine, uM: WT: 99.4 ± 4.4 to TRPV1: 129.7 ± 11.9, p &lt; 0.05; LDH, mU: WT: 132.3± 39.8 to TRPV1-/-: 178.5 ± 44.4, p &lt; 0.05). In vitro, cytokine or chemokine secretion from renal tissues incubated either with 95% O 2 -5% CO 2 or 99% nitrogen (hypoxia) was measured. TNFα, IL-6, or MCP-1 release in response to nitrogen (1 hr) was increased in both strains with a bigger magnitude in TRPV1-/- than WT mice (p&lt;0.05). Blockade of receptors for calcitonin gene-related peptide (CGRP) with CGRP8-38 (10 -7 M) further increased hypoxia-induced MCP-1 release in WT mice (p&lt;0.05). Ex4 suppressed nitrogen (0.5hr)-induced cytokine/chemokine release from the kidneys in WT but not TRPV1-/-mice (WT: IL-6: 0.74 ± 0.08 to 0.66 ± 0.03; TNF-a: 0.73 ± 0.07 to 0.66 ± 0.03; MCP-1: 16.1± 3.5 to 12.7 ± 1.3 pg/g/min, p &lt; 0.05. TRPV1-/-: p&gt;0.05 for all). Moreover, Ex4 increased CGRP release from the renal pelvis in WT ( p &lt; 0.05) but not TRPV1 -/- mice, which can be inhibited by Ex9-39, an Ex4 antagonist. Thus, ablation of TRPV1 or blockade of CGRP receptors enhances hypoxia-induced inflammation and renal injury following I/R. Ex4 suppresses hypoxia-induced cytokine/chemokine release and enhances CGRP release from the kidney only when TRPV1 function and expression are intact, suggesting that TRPV1/CGRP may play a key role mediating Ex4-induced anti-inflammatory effects.

Transient receptor potential vanilloid type 1 channel may modulate opioid reward.

Transient receptor potential vanilloid type 1 (TRPV1), a nonselective cation channel, is a well-known pain-related receptor. TRPV1 involvement in morphine-induced antinociception, tolerance, and withdrawal symptoms has been previously reported. Emerging evidence indicates that TRPV1 may be related to both the cellular and behavioral effects of addictive drugs. In the present study, we investigated the role of TRPV1 in morphine reward using the conditioned place preference (CPP) paradigm in mice. Repeated morphine treatments upregulated TRPV1 expression in the dorsal striatum (DSt). Treatment with a TRPV1 agonist potentiated morphine reward, and pretreatment with TRPV1 antagonists attenuated these effects. Microinjection of a selective TRPV1 antagonist into the DSt significantly inhibited morphine-CPP. In addition, treatment with a TRPV1 antagonist suppressed morphine-induced increases in μ-opioid receptor binding, adenylyl cyclase 1 (AC1), p38 mitogen-activated protein kinase (p38 MAPK), and nuclear factor kappa B (NF-κB) expression in the DSt. Administering a p38 inhibitor not only prevented morphine-CPP, but also prevented morphine-induced NF-κB and TRPV1 activation in the DSt. Furthermore, injecting an NF-κB inhibitor significantly blocked morphine-CPP. Our findings suggest that TRPV1 in the DSt contribute to morphine reward via AC1, p38 MAPK, and NF-κB. Brain TRPV1 may serve as a novel therapeutic target to treat morphine-addictive disorders.

Prolonged exposure to bradykinin and prostaglandin E2 increases TRPV1 mRNA but does not alter TRPV1 and TRPV1b protein expression in cultured rat primary sensory neurons

Sensitisation of the capsaicin receptor, transient receptor potential vanilloid type 1 (TRPV1) ion channel in nociceptive primary sensory neurons (PSN) underlies the development of inflammatory heat hyperalgesia. Removal of the negative-dominant splice variant of the TRPV1 molecule, TRPV1b from TRPV1/TRPV1b heterotetrameric channels, which should be associated with changes in the expression of TRPV1 and TRPV1b transcripts and proteins, has been suggested to contribute to that sensitisation. Respective reverse-transcriptase polymerase chain reaction (RT-PCR) and Western-blotting revealed that both TRPV1 and TRPV1b mRNA, and their encoded proteins are expressed in rat cultured PSN. Sequencing of the RT-PCR products showed that TRPV1b mRNA lacks the entire exon 7. Further, growing PSN for 2 days in the presence of 10μM bradykinin (BK) and 10μM prostaglandin E2 (PGE2) significantly increases TRPV1 responsiveness and TRPV1 mRNA expression, without producing any changes in TRPV1b mRNA, and TRPV1 and TRPV1b protein expression. These data challenge the hypothesis that alterations in the composition of the TRPV1 ion channel contributes to the sensitisation.

Abstract 94: High Sucrose Intake-induced Endoplasmic Reticulum Stress, Inflammation and Fibrosis in hte Pancreas: Role of Trpv1

Excessive consumption of sugar may serve as a primary and independent factor for increased morbidity of diabetes. We test the hypothesis that the transient receptor potential vanilloid type 1 (TRPV1) channels play a protective role against sugar-induced pancreatic endoplasmic reticulum (ER) stress, inflammatory cell infiltration, and tissue fibrosis. Wild-type (WT, C57BL/6) or gene-targeted TRPV1-null mutant (TRPV1 -/- ) mice were fed a normal (CON) or high sucrose diet for 22-23 weeks. TRPV1 ablation impaired glucose tolerance and suppressed glucose-induced insulin release when fed a CON diet (p&lt;0.05). Sucrose intake further impaired glucose tolerance and insulin release in TRPV1 -/- compared to WT mice (p&lt;0.05). Sucrose intake increased pancreatic ER stress, showing elevated levels of chop protein content in both strains and GRP78, XBP-1, and CREB-2 in TRPV1 -/- mice only (p&lt;0.05). TRPV1 ablation increased levels of phosphorylated JNK (WT, 0.12±0.14; TRPV1-/-, 0.31±0.13) and decreased glut2 contents (WT, 1.38±0.24; TRPV1-/-, 0.83±0.09) in the pancreas when fed a CON diet (p&lt;0.05). Sucrose intake further increased levels of pancreatic phosphorylated JNK (WT, 0.89±0.19; TRPV1-/-, 1.05±0.19) and decreased glut2 contents (WT, 0.39±0.04; TRPV1-/-, 0.26±0.16) in both strains (p&lt;0.05). Sucrose intake increased pancreatic TGF-β levels in both strains with exacerbation in TRPV1-/- mice (p&lt;0.05), and increased pancreatic phosphorylated Smad2/3 and collagen levels in TRPV1 -/- mice only (p&lt;0.05). Quantitative immunostaining revealed that sucrose intake enhanced pancreatic infiltration of CD3 positive cells in both strains and macrophage in TRPV1 -/- mice only (p&lt;0.05). Thus, TRPV1 ablation impairs insulin release and glucose tolerance at baseline possibly via increased pancreatic phosphorylated JNK signaling and decreased glut2 expression. Sucrose intake aggravates impairment in insulin release and glucose tolerance when TRPV1 is ablation, possibly via enhancing ER stress, macrophage infiltration, and activation of the TGF-β/Smad pathway leading to pancreatic fibrosis, suggesting preserving TRPV1 expression and function may attenuate pancreatic injury via alleviating inflammatory responses.

TRPV1 Activation BY KAMPO Extract Formulations for Prescription

Transient receptor potential vanilloid type 1 (TRPV1) is a non-selective cation channel activated by capsaicin and heat. Capsaicin has various effects such as pain relief, rubefacient, weight loss, and gastrointestinal protection. Some compounds in Kampo (a traditional Japanese medicine) formulas, such as evodiamine of Evodia fruit, are known to activate TRPV1. But, it is not clear whether TRPV1 is activated by taking Kampo prescriptions. Therefore, the effects of 128 Kampo extract formulations for prescription on the HEK293 cells with/without human TRPV1 expression were examined. The specific increase of intracellular Ca2+ was used as the index of TRPV1 activation. The samples with specific TRPV1 activation were further examined whether they have capsaicin-like contractile effects in mice isolated ileum. In this study, the final concentrations of samples were adjusted to be 1 – 2% of the normal Kampo decoctions. The Daikenchuto which TRPV1 activating ability was already known was served as a positive control. Capsazepine, a TRPV1 antagonist, was used to check the site of action. As a result, 12 Kampo prescriptions have shown stronger TRPV1 activation than Daikenchuto in HEK293 cells with hTRPV1. In the mice isolated ileum, Daiokanzoto, Tokakujokito, Tokishigyakukagoshuyushokyoto and Goshuyuto showed strong contractile effects which was suppressed by the pretreatment of capsazepine. Rubarb and Evodia fruit were suggested to be the main contributing crude drugs for TRPV1 activation. Sennoside B, a main constituent of Rubarb, was found to be a TRPV1 activator. In conclusion, some Kampo prescriptions showed strong TRPV1 activation at the concentrations lower than those in decoction, suggesting the TRPV1 stimulation might play an important part in their pharmacological actions.