capsazepine and Inflammation

Transient receptor potential vanilloid 1 (TRPV1) has been implicated in peripheral inflammation and is a mediator of the inflammatory response to various noxious stimuli. However, the interaction between TRPV1 and

Topics: Analgesics; Animals; Capsaicin; Carrageenan; Disease Models, Animal; Glutamic Acid; Hyperalgesia; Inflammation; Male; Mice; Mice, Inbred ICR; Pain; Phosphorylation; Receptors, N-Methyl-D-Aspartate; Spinal Cord; TRPV Cation Channels

Atypical antipsychotics (AAPs) have the tendency of inducing severe metabolic alterations like obesity, diabetes mellitus, insulin resistance, dyslipidemia and cardiovascular complications. These alterations have been attributed to altered hypothalamic appetite regulation, energy sensing, insulin/leptin signaling, inflammatory reactions and active reward anticipation. Line of evidence suggests that transient receptor potential vanilloid type 1 and 3 (TRPV1 and TRPV3) channels are emerging targets in treatment of obesity, diabetes mellitus and could modulate feed intake. The present study was aimed to investigate the putative role TRPV1/TRPV3 in olanzapine-induced metabolic alterations in mice. Female BALB/c mice were treated with olanzapine for six weeks to induce metabolic alterations. Non-selective TRPV1/TRPV3 antagonist (ruthenium red) and selective TRPV1 (capsazepine) and TRPV3 antagonists (2,2-diphenyltetrahydrofuran or DPTHF) were used to investigate the involvement of TRPV1/TRPV3 in chronic olanzapine-induced metabolic alterations. These metabolic alterations were differentially reversed by ruthenium red and capsazepine, while DPTHF didn't show any significant effect. Olanzapine treatment also altered the mRNA expression of hypothalamic appetite-regulating and nutrient-sensing factors, inflammatory genes and TRPV1/TRPV3, which were reversed with ruthenium red and capsazepine treatment. Furthermore, olanzapine treatment also increased expression of TRPV1/TRPV3 in nucleus accumbens (NAc), TRPV3 expression in ventral tegmental area (VTA), which were reversed by the respective antagonists. However, DPTHF treatment showed reduced feed intake in olanzapine treated mice, which might be due to TRPV3 specific antagonism and reduced hedonic feed intake. In conclusion, our results suggested the putative role TRPV1 in hypothalamic dysregulations and TRPV3 in the mesolimbic pathway; both regulate feeding in olanzapine treated mice.

Topics: Animals; Appetite Regulation; Capsaicin; Coloring Agents; Energy Metabolism; Female; Furans; Gene Expression Regulation; Glucose Tolerance Test; Hypoglycemic Agents; Hypothalamus; Inflammation; Metformin; Mice; Mice, Inbred BALB C; Motor Activity; Olanzapine; Ruthenium Red; Sensory System Agents; TRPV Cation Channels

We demonstrate a novel dual strategy against inflammation and pain through body-wide desensitization of nociceptors via TRPA1. Attenuation of experimental colitis by capsazepine (CPZ) has long been attributed to its antagonistic action on TRPV1 and associated inhibition of neurogenic inflammation. In contrast, we found that CPZ exerts its anti-inflammatory effects via profound desensitization of TRPA1. Micromolar CPZ induced calcium influx in isolated dorsal root ganglion (DRG) neurons from wild-type (WT) but not TRPA1-deficient mice. CPZ-induced calcium transients in human TRPA1-expressing HEK293t cells were blocked by the selective TRPA1 antagonists HC 030031 and A967079 and involved three cysteine residues in the N-terminal domain. Intriguingly, both colonic enemas and drinking water with CPZ led to profound systemic hypoalgesia in WT and TRPV1(-/-) but not TRPA1(-/-) mice. These findings may guide the development of a novel class of disease-modifying drugs with anti-inflammatory and anti-nociceptive effects.

Topics: Acetanilides; Analgesics; Animals; Anti-Inflammatory Agents; Calcium Signaling; Capsaicin; HEK293 Cells; Humans; Inflammation; Mice; Mice, Knockout; Mustard Plant; Oximes; Pain; Plant Oils; Purines; TRPA1 Cation Channel

Peripheral inflammation leads to ipsilateral and contralateral mechanical hyperalgesia. The transient receptor potential channel vanilloid type 1 (TRPV1), a nonselective cation channel expressed in mammalian primary sensory neurons and the spinal cord, may be involved in peripheral inflammation, but there is no consensus on the role of this channel in inflammation-induced mechanical hyperalgesia. Here, we examined the role of TRPV1 channels in carrageenan-induced mechanical hyperalgesia using wild-type and TRPV1-knockout (KO) mice and compared the results with those obtained in mice peripherally administered capsazepine, a TRPV1 antagonist, or capsaicin, a TRPV1 agonist. In the TRPV1-KO mice, ipsilateral mechanical hyperalgesia was significantly reduced during the acute phase (10-60 min), and the contralateral mechanical hyperalgesia nearly disappeared during both the acute and subacute phases. Blocking peripheral TRPV1 using capsazepine before carrageenan administration resulted in similar effects as those observed in the TRPV1-KO mice, except that it was less effective against contralateral mechanical hyperalgesia during the subacute phase. In contrast, capsaicin remarkably decreased ipsilateral and contralateral mechanical hyperalgesia throughout both phases, but this analgesic effect was not observed in the TRPV1-KO mice. Thus, TRPV1 channels could be involved in the development of both ipsilateral and contralateral mechanical hyperalgesia after inflammation. Peripheral TRPV1 could participate in acute hyperalgesia, whereas central TRPV1 may participate in subacute secondary hyperalgesia. Capsaicin potentially acts on both primary and secondary hyperalgesia in a TRPV1-dependent manner.

Topics: Analgesics; Animals; Capsaicin; Carrageenan; Disease Models, Animal; Functional Laterality; Hyperalgesia; Inflammation; Male; Mice, Inbred C57BL; Mice, Knockout; Sensory System Agents; Touch; TRPV Cation Channels

Women with reproductive capability are more likely to suffer from temporomandibular disorders (TMD), with orofacial pain as the most common complaint. In the past, we focused on the role of estradiol in TMD pain through the nervous system. In this study, we explored estradiol's influence on synoviocyte gene expressions involved in the allodynia of the inflamed TMJ. The influence of 17-β-estradiol on NGF and TRPV1 expression in TMJ synovium was determined in vivo and in vitro and analyzed by Western blot and real-time PCR. Complete Freund's adjuvant (CFA) injection into the TMJ was used to induce TMJ arthritis. Capsazepine served as a TRPV1 antagonist. Head withdrawal threshold was examined using a von Frey Anesthesiometer. We observed that estradiol upregulated the expressions of TRPV1 and NGF in a dose-dependent manner. In the primary cultured synoviocytes, TRPV1 was upregulated by lipopolysaccharide (LPS), estradiol, and NGF, while NGF antibodies fully blocked LPS and estradiol-induced upregulation of TRPV1. Activation of TRPV1 in the primary synoviocytes with capsaicin, a TRPV1 agonist, dose-dependently enhanced COX-2 transcription. Moreover, intra-TMJ injection of TRPV1 antagonist, capsazepine, significantly attenuated allodynia of the inflamed TMJ induced by intra-TMJ injection of CFA in female rats. This article presents a possible local mechanism for estradiol that may be involved in TMJ inflammation or pain in the synovial membrane through the pain-related gene TRPV1. This finding could potentially help clinicians understand the sexual dimorphism of TMD pain.

Topics: Animals; Blotting, Western; Capsaicin; Cyclooxygenase 2; Estradiol; Female; Freund's Adjuvant; Hyperalgesia; Inflammation; Nerve Growth Factor; Ovariectomy; Random Allocation; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Temporomandibular Joint; Temporomandibular Joint Disorders; Transcriptional Activation; TRPV Cation Channels; Up-Regulation

The transient receptor potential vanilloid type 1 (TRPV1) is crucial in the pathogenesis of atherosclerosis; yet its role and underlying mechanism in the formation of macrophage foam cells remain unclear. Here, we show increased TRPV1 expression in the area of foamy macrophages in atherosclerotic aortas of apolipoprotein E-deficient mice. Exposure of mouse bone-marrow-derived macrophages to oxidized low-density lipoprotein (oxLDL) upregulated the expression of TRPV1. In addition, oxLDL activated TRPV1 and elicited calcium (Ca(2+)) influx, which were abrogated by the pharmacological TRPV1 antagonist capsazepine. Furthermore, oxLDL-induced lipid accumulation in macrophages was ameliorated by TRPV1 agonists but exacerbated by TRPV1 antagonist. Treatment with TRPV1 agonists did not affect the internalization of oxLDL but promoted cholesterol efflux by upregulating the efflux ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Moreover, the upregulation of ABC transporters was mainly through liver X receptor α-(LXRα-) dependent regulation of transcription. Moreover, the TNF-α-induced inflammatory response was alleviated by TRPV1 agonists but aggravated by the TRPV1 antagonist and LXR α siRNA in macrophages. Our data suggest that LXR α plays a pivotal role in TRPV1-activation-conferred protection against oxLDL-induced lipid accumulation and TNF-α-induced inflammation in macrophages.

Topics: Animals; Atherosclerosis; Blotting, Western; Calcium; Capsaicin; Cells, Cultured; Chromatin Immunoprecipitation; Inflammation; Lipoproteins, LDL; Liver X Receptors; Macrophages; Mice; Orphan Nuclear Receptors; RNA, Small Interfering; TRPV Cation Channels; Tumor Necrosis Factor-alpha

The principal aim of the study was to determine the influence of influenza A virus infection on capsaicin-induced relaxation responses in mouse isolated tracheal segments and clarify the underlying mechanisms. Anesthetized mice were intranasally inoculated with influenza A/PR-8/34 virus (VIRUS) or vehicle (SHAM), and 4 days later tracheal segments were harvested for isometric tension recording and biochemical and histologic analyses. Capsaicin induced dose-dependent relaxation responses in carbachol-contracted SHAM trachea (e.g., 10 μM capsaicin produced 66 ± 4% relaxation; n = 11), which were significantly inhibited by capsazepine [transient receptor potential vanilloid type 1 (TRPV1) antagonist], (2S,3S)-3-{[3,5-bis(trifluoromethyl)phenyl]methoxy}-2-phenylpiperidine hydrochloride (L-733,060) [neurokinin 1 (NK₁) receptor antagonist], indomethacin [cyclooxygenase (COX) inhibitor], and the combination of 6-isopropoxy-9-oxoxanthene-2-carboxylic acid (AH6809) and 7-[5α-([1S,1α(Z)-biphenyl]-4-ylmethoxy)-2β-(4-morpholinyl)-3-oxocyclopentyl]-4-heptenoic acid, calcium salt, hydrate (AH23848) [E-prostanoid (EP)₂ and EP₄ receptor antagonists, respectively], indicating that capsaicin-induced relaxation involved the TRPV1-mediated release of substance P (SP), activation of epithelial NK₁ receptors, and production of COX products capable of activating relaxant EP₂/EP₄ receptors. Consistent with this postulate, capsaicin-induced relaxation was associated with the significant release of SP and prostaglandin E₂ (PGE₂) from mouse tracheal segments. As expected, influenza A virus infection was associated with widespread disruption of the tracheal epithelium. Tracheal segments from VIRUS mice responded weakly to capsaicin (7 ± 3% relaxation) and were 25-fold less responsive to SP than tracheas from SHAM mice. In contrast, relaxation responses to exogenous PGE₂ and the β-adrenoceptor agonist isoprenaline were not inhibited in VIRUS trachea. Virus infection was associated with impaired capsaicin-induced release of PGE₂, but the release of SP was not affected. In summary, influenza A virus infection profoundly inhibits capsaicin- and SP-induced relaxation responses, most likely by inhibiting the production of PGE₂.

Topics: Animals; Biphenyl Compounds; Bronchoalveolar Lavage Fluid; Capsaicin; Carbachol; Cyclooxygenase Inhibitors; Dinoprostone; Dose-Response Relationship, Drug; Indomethacin; Inflammation; Influenza A virus; Isoproterenol; Leukocytes; Male; Mice; Mice, Inbred BALB C; Models, Biological; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Orthomyxoviridae Infections; Piperidines; Prostaglandin Antagonists; Respiratory Mucosa; Specific Pathogen-Free Organisms; Substance P; Trachea; TRPV Cation Channels; Xanthones

We investigated whether capsaicin induces itching in skin with existing inflammation. We induced skin inflammation by intradermal injection of complete Freund's adjuvant (CFA) in the neck of mice. Four days later, we injected capsaicin in the same area and counted the number of scratching bouts for 30 min. We examined potential effects on pain in parallel experiments in which CFA and capsaicin were intradermally injected into hind paws. We used the time spent licking the hind paws during the 15 min after capsaicin injection as an estimate of pain. Capsaicin injection into the skin pretreated with CFA, but not into healthy skin, induced scratching. The scratching behavior was reduced by pretreatment with naloxone or capsazepine, selective antagonists for transient receptor potential vanilloid receptor-1 (TRPV1), but not morphine or mepyramine, selective antagonists for histamine 1 receptor. In animals injected with capsaicin into the hind paws, licking behavior was significantly inhibited via a μ-receptor-dependent mechanism. Our results show that TRPV1 activation, which normally induces pain, evokes an itch-related response in the presence of inflammation. This model may be interesting for future studies to explore the mechanism of a painful stimuli-induced itch observed under pathological conditions.

Topics: Adjuvants, Immunologic; Animals; Anti-Inflammatory Agents, Non-Steroidal; Behavior, Animal; Capsaicin; Dimethyl Sulfoxide; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Freund's Adjuvant; Inflammation; Injections, Intradermal; Male; Mice; Mice, Inbred C57BL; Morphine; Naloxone; Pain; Pruritus; Receptors, Opioid, mu; Reflex; Sensory System Agents; Skin; Time Factors; TRPV Cation Channels

Hydrogen sulfide (H(2)S) has been shown to induce transient receptor potential vanilloid 1 (TRPV1)-mediated neurogenic inflammation in polymicrobial sepsis. However, endogenous neural factors that modulate this event and the molecular mechanism by which this occurs remain unclear. Therefore, this study tested the hypothesis that whether substance P (SP) is one important neural element that implicates in H(2)S-induced neurogenic inflammation in sepsis in a TRPV1-dependent manner, and if so, whether H(2)S regulates this response through activation of the extracellular signal-regulated kinase-nuclear factor-κB (ERK-NF-κB) pathway. Male Swiss mice were subjected to cecal ligation and puncture (CLP)-induced sepsis and treated with TRPV1 antagonist capsazepine 30 minutes before CLP. DL-propargylglycine (PAG), an inhibitor of H(2)S formation, was administrated 1 hour before or 1 hour after sepsis, whereas sodium hydrosulfide (NaHS), an H(2)S donor, was given at the same time as CLP. Capsazepine significantly attenuated H(2)S-induced SP production, inflammatory cytokines, chemokines, and adhesion molecules levels, and protected against lung and liver dysfunction in sepsis. In the absence of H(2)S, capsazepine caused no significant changes to the PAG-mediated attenuation of lung and plasma SP levels, sepsis-associated systemic inflammatory response and multiple organ dysfunction. In addition, capsazepine greatly inhibited phosphorylation of ERK(1/2) and inhibitory κBα, concurrent with suppression of NF-κB activation even in the presence of NaHS. Furthermore, capsazepine had no effect on PAG-mediated abrogation of these levels in sepsis. Taken together, the present findings show that H(2)S regulates TRPV1-mediated neurogenic inflammation in polymicrobial sepsis through enhancement of SP production and activation of the ERK-NF-κB pathway.

Topics: Animals; Capsaicin; Cell Nucleus; Chemokines; Cytokines; Extracellular Signal-Regulated MAP Kinases; Hydrogen Sulfide; Inflammation; Male; Mice; NF-kappa B; Phosphorylation; Sepsis; Substance P; TRPV Cation Channels

This protocol describes microsphere-based protease assays for use in flow cytometry and high-throughput screening. This platform measures a loss of fluorescence from the surface of a microsphere due to the cleavage of an attached fluorescent protease substrate by a suitable protease enzyme. The assay format can be adapted to any site or protein-specific protease of interest and results can be measured in both real time and as endpoint fluorescence assays on a flow cytometer. Endpoint assays are easily adapted to microplate format for flow cytometry high-throughput analysis and inhibitor screening.

Topics: Animals; Biotinylation; Flow Cytometry; Fluorescence Resonance Energy Transfer; Green Fluorescent Proteins; High-Throughput Screening Assays; Humans; Inflammation; Kinetics; Microspheres; Peptide Hydrolases; Peptides; Reproducibility of Results; Temperature

Given that the pharmacological or genetic inactivation of fatty acid amide hydrolase (FAAH) counteracts pain and inflammation, and on the basis of the established involvement of transient receptor potential vanilloid type-1 (TRPV1) channels in inflammatory pain, we tested the capability of a dual FAAH/TRPV1 blocker, N-arachidonoyl-serotonin (AA-5-HT), to relieve oedema and pain in a model of acute inflammation, and compared its efficacy with that of a single FAAH inhibitor (URB597) or TRPV1 antagonist (capsazepine). Acute inflammation was induced by intraplantar injection of lambda-carrageenan into mice and the anti-inflammatory and anti-nociceptive actions of AA-5-HT were assessed at different doses, time points and treatment schedule. In addition, endocannabinoid levels were measured in paw skin and spinal cord. Systemic administration of AA-5-HT elicited dose-dependent anti-oedemigen and anti-nociceptive effects, whereas it was devoid of efficacy when given locally. When tested in a therapeutic regimen, the compound retained comparable anti-inflammatory effects. TRPV1 receptor mediated the anti-inflammatory property of AA-5-HT, whereas both CB(1) and TRPV1 receptors were involved in its anti-hyperalgesic activity. These effects were accompanied by an increase of the levels of the endocannabinoid anandamide (AEA) in both inflamed paw and spinal cord. AA-5-HT was more potent than capsazepine as anti-oedemigen and anti-hyperalgesic drug, whereas it shows an anti-oedemigen property similar to URB597, which was, however, devoid of the anti-nociceptive effect. AA-5-HT did not induce unwanted effects on locomotion and body temperature. In conclusion AA-5-HT has both anti-inflammatory and anti-hyperalgesic properties and its employment offers advantages, in terms of efficacy and lack of adverse effects, deriving from its dual activity.

Topics: Amidohydrolases; Analgesics; Animals; Anti-Inflammatory Agents; Arachidonic Acids; Benzamides; Capsaicin; Carbamates; Carrageenan; Hyperalgesia; Inflammation; Mice; Receptor, Cannabinoid, CB1; Serotonin; TRPV Cation Channels

We previously reported that vanilloid receptor type 1 (VR1, or TRPV1) was up-regulated in dorsal root ganglion (DRG) and the spinal dorsal horn after chronic inflammatory pain produced by complete Freund's adjuvant (CFA) injection into the plantar of rat hind paw. In the present study, we found that subcutaneous or intrathecal application of capsazepine (CPZ), a TRPV1 competitive antagonist, could inhibit thermal hyperalgesia on day 1 and on day 14 but not on day 28 after CFA injection. With extracellular electrophysiological recording, the effect of CPZ on noxious electrical or heat stimulation evoked responses of wide dynamic range (WDR) neurons in the deep layers of the spinal dorsal horn was evaluated. Under noxious electrical stimulation to sciatic nerve, CPZ applied to the spinal cord produced an inhibition on Adelta- and C-fiber evoked responses of WDR neurons on day 1 and 14, but not on day 28. Under radiant heat stimulation to the receptive field skin, subcutaneous application of CPZ significantly inhibited the background activity and extended the response latency of WDR neurons on day 14. These results provide new evidence for the functional significance of TRPV1 at the early stage, but not the late stage, in the rat model of CFA-induced inflammatory pain.

Topics: Animals; Capsaicin; Chronic Disease; Electric Stimulation; Evoked Potentials; Freund's Adjuvant; Hot Temperature; Hyperalgesia; Inflammation; Injections, Spinal; Male; Pain; Physical Stimulation; Posterior Horn Cells; Rats; Rats, Sprague-Dawley; Sciatic Nerve; Spinal Cord; TRPV Cation Channels

TRPA1 is an excitatory ion channel expressed by a subpopulation of primary afferent somatosensory neurons that contain substance P and calcitonin gene-related peptide. Environmental irritants such as mustard oil, allicin, and acrolein activate TRPA1, causing acute pain, neuropeptide release, and neurogenic inflammation. Genetic studies indicate that TRPA1 is also activated downstream of one or more proalgesic agents that stimulate phospholipase C signaling pathways, thereby implicating this channel in peripheral mechanisms controlling pain hypersensitivity. However, it is not known whether tissue injury also produces endogenous proalgesic factors that activate TRPA1 directly to augment inflammatory pain. Here, we report that recombinant or native TRPA1 channels are activated by 4-hydroxy-2-nonenal (HNE), an endogenous alpha,beta-unsaturated aldehyde that is produced when reactive oxygen species peroxidate membrane phospholipids in response to tissue injury, inflammation, and oxidative stress. HNE provokes release of substance P and calcitonin gene-related peptide from central (spinal cord) and peripheral (esophagus) nerve endings, resulting in neurogenic plasma protein extravasation in peripheral tissues. Moreover, injection of HNE into the rodent hind paw elicits pain-related behaviors that are inhibited by TRPA1 antagonists and absent in animals lacking functional TRPA1 channels. These findings demonstrate that HNE activates TRPA1 on nociceptive neurons to promote acute pain, neuropeptide release, and neurogenic inflammation. Our results also provide a mechanism-based rationale for developing novel analgesic or anti-inflammatory agents that target HNE production or TRPA1 activation.

Topics: Acrolein; Aldehydes; Ankyrins; Calcium Channels; Cell Line; Cloning, Molecular; Humans; Inflammation; Pain; Patch-Clamp Techniques; TRPA1 Cation Channel; TRPC Cation Channels

Cannabidiol, the major psycho-inactive component of cannabis, has substantial anti-inflammatory and immunomodulatory effects. This study investigated its therapeutic potential on neuropathic (sciatic nerve chronic constriction) and inflammatory pain (complete Freund's adjuvant intraplantar injection) in rats. In both models, daily oral treatment with cannabidiol (2.5-20 mg/kg to neuropathic and 20 mg/kg to adjuvant-injected rats) from day 7 to day 14 after the injury, or intraplantar injection, reduced hyperalgesia to thermal and mechanical stimuli. In the neuropathic animals, the anti-hyperalgesic effect of cannabidiol (20 mg/kg) was prevented by the vanilloid antagonist capsazepine (10 mg/kg, i.p.), but not by cannabinoid receptor antagonists. Cannabidiol's activity was associated with a reduction in the content of several mediators, such as prostaglandin E(2) (PGE(2)), lipid peroxide and nitric oxide (NO), and in the over-activity of glutathione-related enzymes. Cannabidiol only reduced the over-expression of constitutive endothelial NO synthase (NOS), without significantly affecting the inducible form (iNOS) in inflamed paw tissues. Cannabidiol had no effect on neuronal and iNOS isoforms in injured sciatic nerve. The compound's efficacy on neuropathic pain was not accompanied by any reduction in nuclear factor-kappaB (NF-kappaB) activation and tumor necrosis factor alpha (TNFalpha) content. The results indicate a potential for therapeutic use of cannabidiol in chronic painful states.

Topics: Administration, Oral; Animals; Cannabidiol; Cannabinoid Receptor Antagonists; Cannabis; Capsaicin; Chronic Disease; Dinoprostone; Freund's Adjuvant; Hyperalgesia; Inflammation; Lipid Peroxides; Male; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Pain; Pain Measurement; Rats; Rats, Wistar; Sciatic Neuropathy; Tumor Necrosis Factor-alpha

Cannabinoids, such as anandamide, are involved in pain transmission. We evaluated the effects of AM404 (N-(4-hydroxyphenyl)-5Z,8Z,11Z,14Z-eicosatetraenamide), an anandamide reuptake inhibitor, monitoring the expression of c-fos, a marker of activated neurons and the pain-related behaviours using formalin test. The study was carried out in an experimental model of inflammatory pain made by a single injection of formalin in rat hind paws. Formalin test showed that the antinociceptive effect of AM404 was evident in phase I. We found that Fos-positive neurons in dorsal superficial and deep laminae of the lumbar spinal cord increased in formalin-injected animals and that AM404 significantly reduced Fos induction. Co-administration of cannabinoid CB(1) receptor antagonist (AM251), cannabinoid CB(2) receptor antagonist (AM630) and transient receptor potential vanilloid type 1 (TRPV-1) antagonist (capsazepine), attenuate the inhibitory effect of AM404 and this effect was higher using cannabinoid CB(2) and vanilloid TRPV-1 receptor antagonists. These results suggest that AM404 could be a useful drug to reduce inflammatory pain in our experimental model and that cannabinoid CB(2) receptor and vanilloid TRPV-1 receptor, and to a lesser extent, the cannabinoid CB(1) receptor are involved.

Topics: Animals; Arachidonic Acids; Capsaicin; Endocannabinoids; Immunohistochemistry; Indoles; Inflammation; Male; Pain; Pain Measurement; Piperidines; Polyunsaturated Alkamides; Proto-Oncogene Proteins c-fos; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Spinal Cord; TRPV Cation Channels

In the present paper, we describe the analgesic effects induced by the transient receptor potential vanilloid type 1 (TRPV1) antagonist, capsazepine, and the TRPV1 agonist, resiniferatoxin, on the thermal hyperalgesia induced by the presence of a tibial osteosarcoma or an inflammatory process in mice. The administration of capsazepine abolished the osteosarcoma-induced hyperalgesia at a dose range (3-10 mg/kg; s.c.) ineffective to inhibit the hyperalgesia elicited by the intraplantar administration of complete Freund's adjuvant (CFA). In contrast, the administration of resiniferatoxin (0.01-0.1 mg/kg; s.c.) inhibited both the osteosarcoma- and the CFA-induced hyperalgesia. Remarkably, a single dose of resiniferatoxin abolished the osteosarcoma-induced hyperalgesia for several days and completely prevented the instauration of thermal hyperalgesia when administered at the initial stages of osteosarcoma development. The potential of drugs acting through TRPV1 for the management of some types of bone cancer pain is proposed.

Topics: Analgesics; Analysis of Variance; Animals; Bone Neoplasms; Capsaicin; Cell Line; Disease Models, Animal; Diterpenes; Dose-Response Relationship, Drug; Freund's Adjuvant; Functional Laterality; Inflammation; Mice; Mice, Inbred C3H; Osteosarcoma; Pain; Pain Measurement; Reaction Time; Time Factors

A lowered threshold to the cough response frequently accompanies chronic airway inflammatory conditions. However, the mechanism(s) that from chronic inflammation results in a lowered cough threshold is poorly understood. Irritant agents, including capsaicin, resiniferatoxin, and citric acid, elicit cough in humans and in experimental animals through the activation of the transient receptor potential vanilloid 1 (TRPV1). Protease-activated receptor-2 (PAR2) activation plays a role in inflammation and sensitizes TRPV1 in cultured sensory neurons by a PKC-dependent pathway. Here, we have investigated whether PAR2 activation exaggerates TRPV1-dependent cough in guinea pigs and whether protein kinases are involved in the PAR2-induced cough modulation. Aerosolized PAR2 agonists (PAR2-activating peptide and trypsin) did not produce any cough per se. However, they potentiated citric acid- and resiniferatoxin-induced cough, an effect that was completely prevented by the TRPV1 receptor antagonist capsazepine. In contrast, cough induced by hypertonic saline, a stimulus that provokes cough in a TRPV1-independent manner, was not modified by aerosolized PAR2 agonists. The PKC inhibitor GF-109203X, the PKA inhibitor H-89, and the cyclooxygenase inhibitor indomethacin did not affect cough induced by TRPV1 agonists, but abated the exaggeration of this response produced by PAR2 agonists. In conclusion, PAR2 stimulation exaggerates TRPV1-dependent cough by activation of diverse mechanism(s), including PKC, PKA, and prostanoid release. PAR2 activation, by sensitizing TRPV1 in primary sensory neurons, may play a role in the exaggerated cough observed in certain airways inflammatory diseases such as asthma and chronic obstructive pulmonary disease.

Topics: Animals; Capsaicin; Citric Acid; Cough; Cyclic AMP-Dependent Protein Kinases; Cyclooxygenase Inhibitors; Diterpenes; Guinea Pigs; Indomethacin; Inflammation; Isoquinolines; Male; Neurons, Afferent; Protein Kinase C; Protein Kinase Inhibitors; Receptor, PAR-2; Saline Solution, Hypertonic; Sulfonamides; TRPV Cation Channels; Trypsin

Delta-9 tetrahydrocannabinol (Delta(9)-THC) and (-)-cannabidiol ((-)-CBD) are major constituents of the Cannabis sativa plant with different pharmacological profiles: (Delta(9)-THC activates cannabinoid CB(1) and CB(2) receptors and induces psychoactive and peripheral effects. (-)-CBD possesses no, or very weak affinity for these receptors. We tested a series of (+)- and (-)-CBD derivatives for central and peripheral effects in mice. None of the (-)-CBD derivatives were centrally active, yet most inhibited intestinal motility. Of the five (+)-CBD derivatives, all with CB(1) receptor affinity, only (+)-7-OH-CBD-DMH (DMH=1,1-dimethylheptyl), acted centrally, while all five arrested defecation. The effects of (+)-CBD-DMH and (+)-7-OH-CBD-DMH were inhibited by the CB(1) receptor antagonist SR141716. The CB(2) receptor antagonist SR144528, and the vanilloid TRPV1 receptor antagonist capsazepine, had no influence. Further, the (-)-CBD derivatives (-)-7-COOH-CBD and (-)-7-COOH-CBD-DMH, displayed antiinflammatory activity. We suggest that (+)-CBD analogues have mixed agonist/antagonist activity in the brain. Second, (-)-CBD analogues which are devoid of cannabinoid receptor affinity but which inhibit intestinal motility, suggest the existence of a non-CB(1), non-CB(2) receptor. Therefore, such analogues should be further developed as antidiarrheal and/or antiinflammatory drugs. We propose to study the therapeutic potential of (-)- and (+)-CBD derivatives for complex conditions such as inflammatory bowel disease and cystic fibrosis.

Topics: Animals; Binding, Competitive; Body Temperature; Camphanes; Cannabidiol; Capsaicin; Drug Interactions; Ear, External; Gastrointestinal Motility; Inflammation; Mice; Mice, Inbred ICR; Mice, Inbred Strains; Motor Activity; Pain Measurement; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant

The intra-plantar acute administration of 10 microg of capsaicin to mice which had received complete Freund's adjuvant (CFA) 1 week before inhibits the thermal inflammatory hyperalgesia it induces and even produces a long-lasting analgesia for at least 2 weeks. In this study, we show that the administration of capsaicin (10 microg) also reduces the immediate licking behavior evoked by the intra-plantar administration of a lower dose of capsaicin (0.1 microg), the duration of this inhibitory effect being greater in CFA-inflamed mice (at least 2 weeks) than in non-inflamed animals (less than 4 days). Since this reduction of capsaicin-induced licking behavior may be interpreted as a consequence of the transient receptor potential vanilloid 1 receptor (TRPV1) unresponsiveness, we conclude that the administration of 10 microg of capsaicin into inflamed tissues can render the TRPV1 desensitised. We next explored whether endogenous vanilloids released during inflammation contribute to maintain the analgesia triggered by exogenous capsaicin. The acute administration of capsazepine (10 microg; intra-plantarly (i.pl.)) abolished the analgesic effect induced by the injection of capsaicin 1 week before in inflamed mice. From these results, it may be proposed that the maintenance by endovanilloids of the TRPV1 desensitisation induced by capsaicin could contribute to prolonging the analgesic effect induced by this agonist in inflamed tissues.

Topics: Adjuvants, Immunologic; Analgesics; Animals; Capsaicin; Freund's Adjuvant; Hyperalgesia; Inflammation; Male; Mice; Pain; Pain Measurement; TRPV Cation Channels

Agonists of the vanilloid receptor type 1 (VR1), such as capsaicin, induce an analgesic effect following an initial excitatory response. It has been demonstrated that the vanilloid system plays an important role in inflammatory hyperalgesia. In accordance, we show that the VR1 antagonist capsazepine (30 microg; i.pl.) prevented the thermal hyperalgesia induced by carrageenan or complete Freund's adjuvant (CFA) in mice. Furthermore, we studied whether this inflammation-induced activation of the vanilloid system could enhance the analgesic properties of capsaicin. A single administration of capsaicin (10 microg; i.pl.) induced in control mice an analgesic effect that lasted for 2 days. In contrast, in carrageenan-treated animals, the analgesic effect of this dose of capsaicin lasted for 6 days and in CFA-treated mice for 30 days. This prolongation of capsaicin-induced analgesia during inflammation was mediated through VR1 since it was completely blocked by coadministration of capsazepine (10 microg). Licking behavior induced by capsaicin in carrageenan- and CFA-treated mice was greater than in control animals. However, although capsaicin induced a more prolonged analgesia in CFA-treated mice, the licking behavior was greater in the carrageenan-treated group, suggesting that the prolongation of analgesia is independent of the initial nociceptive input. Overall, these results show that the analgesic effects of capsaicin are importantly enhanced during inflammation, supporting the fact that the stimulation of VR1 could perhaps constitute a suitable strategy to avoid inflammatory hyperalgesia.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Capsaicin; Carrageenan; Disease Models, Animal; Freund's Adjuvant; Hot Temperature; Hyperalgesia; Inflammation; Male; Mice; Receptors, Drug; Time Factors

Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyperalgesic compound in a rat model of acute inflammation. We examined whether the CBD antihyperalgesic effect could be mediated by cannabinoid receptor type 1 (CB1) or cannabinoid receptor type 2 (CB2) and/or by transient receptor potential vanilloid type 1 (TRPV1). Rats received CBD (10 mg kg(-1)) and the selective antagonists: SR141716 (N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) for CB1, SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide) for CB2 and capsazepine (CPZ) for TRPV1 receptors. The intraplantar injection of carrageenan in rats induced a time-dependent thermal hyperalgesia, which peaked at 3 h and decreased at the following times. CBD, administered 2 h after carrageenan, abolished the hyperalgesia to the thermal stimulus evaluated by plantar test. Neither SR141716 (0.5 mg kg(-1)) nor SR144528 (3 and 10 mg kg(-1)) modified the CBD-induced antihyperalgesia; CPZ partially at the lowest dose (2 mg kg(-1)) and fully at the highest dose (10 mg kg(-1)) reversed this effect. These results demonstrate that TRPV1 receptor could be a molecular target of the CBD antihyperalgesic action.

Topics: Administration, Oral; Animals; Camphanes; Cannabidiol; Capsaicin; Carrageenan; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Therapy, Combination; Hyperalgesia; Inflammation; Italy; Male; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Drug; Rimonabant; Time Factors

Vanilloid receptor type 1 (VR1) (TRPV1) is a ligand-gated ion channel expressed on sensory nerves that responds to noxious heat, protons, and chemical stimuli such as capsaicin. Herein, we have examined the activity of the VR1 antagonist capsazepine in models of inflammatory and neuropathic pain in the rat, mouse, and guinea pig. In naïve animals, subcutaneous administration of capsazepine (10-100 mg/kg s.c.) did not affect withdrawal thresholds to noxious thermal or mechanical stimuli. However, pretreatment with capsazepine prevented the development of mechanical hyperalgesia induced by intraplantar injection of capsaicin, with a similar potency in all three species. Capsazepine (up to 100 mg/kg s.c.) did not affect mechanical hyperalgesia in the Freund's complete adjuvant (FCA)-inflamed hind paw of the rat or mouse. Strikingly, capsazepine (3-30 mg/kg s.c.) produced up to 44% reversal of FCA-induced mechanical hyperalgesia in the guinea pig. Capsazepine also produced significant reversal of carageenan-induced thermal hyperalgesia in the guinea pig at 30 mg/kg s.c., but was ineffective in the rat. Similarly, in the partial sciatic nerve ligation model of neuropathic pain, capsazepine was surprisingly effective in the guinea pig, producing up to 80% reversal of mechanical hyperalgesia (1-30 mg/kg s.c.) but had no effect in the rat or mouse. These data show that VR1 antagonists have antihyperalgesic activity in animal models of chronic inflammatory and neuropathic pain, and illustrate species differences in the in vivo pharmacology of VR1 that correlate with differences in pharmacology previously seen in vitro.

Topics: Algorithms; Animals; Anticonvulsants; Capsaicin; Carbamazepine; Dose-Response Relationship, Drug; Guinea Pigs; Hyperalgesia; Inflammation; Male; Mice; Mice, Inbred C57BL; Peripheral Nervous System Diseases; Rats; Rats, Wistar; Receptors, Drug; Sciatic Nerve

The epsilon-isozyme of protein kinase C (PKCepsilon) and the vanilloid receptor 1 (VR1) are both expressed in dorsal root ganglion (DRG) neurons and are reported to be predominantly and specifically involved in nociceptive function. Using phosphospecific antibody against the C-terminal hydrophobic site Ser729 of PKCepsilon as a marker of enzyme activation, the state-dependent activation of PKCepsilon, as well as the expression of VR1 in rat DRG neurons, was evaluated in different experimental pain models in vivo. Quantitative analysis showed that phosphorylation of PKCepsilon in DRG neurons was significantly up-regulated after carrageen- and Complete Freund's Adjuvant-induced inflammation, while it was markedly down-regulated after chronic constriction injury. A double-labeling study showed that phosphorylation of PKCepsilon was expressed predominantly in VR1 immunoreactivity positive small diameter DRG neurons mediating the nociceptive information from peripheral tissue to spinal cord. The VR1 protein expression showed no significant changes after either inflammation or chronic constriction injury. These data indicate that functional activation of PKCepsilon has a close relationship with the production of inflammatory hyperalgesia and the sensitization of the nociceptors. Inflammatory mediator-induced activation of PKCepsilon and subsequent sensitization of VR1 to noxious stimuli by PKCepsilon may be involved in nociceptor sensitization.

Topics: Animals; Behavior, Animal; Capsaicin; Carrageenan; Disease Models, Animal; Diterpenes; Freund's Adjuvant; Ganglia, Spinal; Hindlimb; Hyperalgesia; Inflammation; Ligation; Male; Neurons; Nociceptors; Pain; Pain Measurement; Peripheral Nervous System Diseases; Phosphorylation; Protein Kinase C; Protein Kinase C-epsilon; Rats; Rats, Sprague-Dawley; Receptors, Drug

Vanilloid VR1 receptors are located in the dorsal horn of the spinal cord. The aim of the present study was to determine the role of spinal vanilloid receptors (VR1) during nociceptive processing in control and inflamed rats. Effects of spinal administration of capsazepine (0.5-30 microM/50 microl), a competitive VR1 antagonist, on innocuous and noxious evoked responses of spinal neurones were studied in halothane anaesthetised rats. Transcutaneous electrical-evoked neuronal responses of spinal neurones were recorded in control and carrageenan (2%, 3 h) inflamed rats. Spinal application of capsazepine did not significantly alter Abeta-fibre evoked responses of neurones, however Adelta-fibre evoked responses were significantly inhibited by capsazepine in both non-inflamed and carrageenan inflamed rats (30 microM: non-inflamed 31+/-8% of control, P<0.01: carrageenan-inflamed 43+/-6% of control, P<0.01). Similarly, the evoked C-fibre mediated post-discharge responses of spinal neurones in non-inflamed and carrageenan inflamed rats were reduced by capsazepine (30 microM: non-inflamed 41+/-14% of control, P<0.01: carrageenan-inflamed 31+/-9% of control, P<0.01). These results demonstrate a role of spinal VR1 receptors during noxious, but not innocuous transmission, at the level of the spinal cord. The degree of effect of capsazepine on evoked neuronal responses was similar in control and inflamed rats, suggesting that the role of spinal VR1 receptors is not altered following short-term peripheral inflammation. Our data suggest that following noxious peripheral stimulation, spinal VR1 receptors are activated, but the endogenous ligands mediating this effect remain to be elucidated.

Topics: Action Potentials; Afferent Pathways; Animals; Capsaicin; Carrageenan; Dose-Response Relationship, Drug; Inflammation; Injections, Spinal; Male; Nerve Fibers; Nerve Fibers, Myelinated; Neural Inhibition; Nociceptors; Pain; Posterior Horn Cells; Presynaptic Terminals; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, Drug

The rat skin-saphenous nerve preparation was used to record from mechano-heat sensitive C-fibers whose receptive fields were superfused with various solutions of low pH and of bradykinin, serotonin and prostaglandin E2. Only synchronous application of protons and mediators resulted in a significant nearly three-fold augmentation of the nociceptive pH response, and capsazepine (10(-5) M) did not block this short-lived enhancement. Thus, it does not seem to involve the capsaicin receptor (VRI) which is in contrast to a previous finding from cultured sensory neurons.

Topics: Animals; Bradykinin; Capsaicin; Dinoprostone; Drug Interactions; Ganglia, Spinal; Hydrogen-Ion Concentration; Inflammation; Inflammation Mediators; Male; Nerve Fibers; Nociceptors; Oxytocics; Protons; Rats; Rats, Wistar; Serotonin; Signal Transduction; Skin

Capsaicin, a pungent ingredient of hot peppers, causes excitation of small sensory neurons, and thereby produces severe pain. A nonselective cation channel activated by capsaicin has been identified in sensory neurons and a cDNA encoding the channel has been cloned recently. However, an endogenous activator of the receptor has not yet been found. In this study, we show that several products of lipoxygenases directly activate the capsaicin-activated channel in isolated membrane patches of sensory neurons. Among them, 12- and 15-(S)-hydroperoxyeicosatetraenoic acids, 5- and 15-(S)-hydroxyeicosatetraenoic acids, and leukotriene B(4) possessed the highest potency. The eicosanoids also activated the cloned capsaicin receptor (VR1) expressed in HEK cells. Prostaglandins and unsaturated fatty acids failed to activate the channel. These results suggest a novel signaling mechanism underlying the pain sensory transduction.

Topics: Animals; Capsaicin; Cell Line; Cells, Cultured; Dinoprostone; Eicosanoids; Ganglia, Spinal; Humans; Hydroxyeicosatetraenoic Acids; Inflammation; Ion Channel Gating; Leukotriene B4; Leukotrienes; Ligands; Lipid Peroxides; Lipoxygenase; Molecular Structure; Neurons, Afferent; Prostaglandin D2; Prostaglandin H2; Prostaglandins H; Rats; Receptors, Drug; Structure-Activity Relationship

Whole cell membrane currents induced by the inflammatory mediators, bradykinin, 5-hydroxytryptamine (5-HT) and prostaglandin E2, were investigated in capsaicin-sensitive dorsal root ganglion (DRG) neurons from newborn rats grown on a monolayer of hippocampal glia without nerve growth factor (NGF). When firmly attached to an underlying cell, the neurons survived >14 days without growing extensive processes. A majority of the small diameter neurons ( approximately 80%) exhibited sensitivity to capsaicin (3-6 muM) and this was enhanced in solution of low pH. In acidic extracellular solution (pH 6.1), the combination of bradykinin (10 microM), 5-HT (10 microM) and prostaglandin E2 (1 microM) induced an inward membrane current in all capsaicin-sensitive DRG neurons (n = 43). The current exceeded the sustained, low pH-induced membrane current by 205 +/- 53 (SE) pA. The combination of acidic inflammatory mediators was ineffective in cells that were insensitive to capsaicin. In capsaicin-sensitive neurons, the inflammatory mediators when applied singly or in any combination of two, induced no membrane currents or small current at pH 7.3 and 6.1. Capsazepine (10 microM), the capsaicin antagonist, completely inhibited the facilitatory action of inflammatory mediator combination but not the sustained inward current induced by acidic extracellular solution (pH 6.1 or 5.5). It is suggested that the inflammatory mediators, bradykinin,5-HT, and prostaglandin E2 together act as endogenous mediators at capsaicin receptors to generate an inward current when the ion channel is protonized.

Topics: Animals; Animals, Newborn; Bradykinin; Capsaicin; Cells, Cultured; Coculture Techniques; Dinoprostone; Drug Synergism; Ganglia, Spinal; Hippocampus; Hydrogen-Ion Concentration; Inflammation; Ion Channel Gating; Neuroglia; Neurons, Afferent; Rats; Receptors, Drug; Serotonin; Stimulation, Chemical

In the present study, the presence of an endogenous capsaicin-like substance and the role of capsaicin receptors in nociception during inflammation were assessed using Fos immunohistochemistry and the paw-withdrawal test in rats. Intradermal injection of carrageenan in the hind-paw produced inflammation in the foot pad, increased the number of cells exhibiting Fos-like immunoreactivity in the dorsal horn of the spinal cord, and decreased the paw-withdrawal latency. Intradermal injection of capsazepine, a capsaicin-receptor antagonist, significantly reduced the number of cells exhibiting Fos-like immunoreactivity, significantly increased the paw-withdrawal latency, but did not decrease inflammation induced by carrageenan injection. Intradermal injection of capsaicin or formalin also increased Fos-positive neurons. Capsaicin- or formalin-induced Fos expression was reduced in both cases by pretreatment of capsazepine, but to a much lesser extent for formalin. The capsazepine inhibition of carrageenan inflammation-induced hyperalgesic responses strongly suggests that an endogenous capsaicin-like substance is released in inflamed tissues and produces nociceptive neural impulses by acting on capsaicin receptors present on sensory neurons. Furthermore, our results indicate that capsaicin receptors take part only in generating nociceptive signals in sensory neurons, but not in activating the inflammation-promoting cells.

Topics: Animals; Capsaicin; Carrageenan; Functional Laterality; Hindlimb; Hyperalgesia; Inflammation; Male; Neurons; Pain; Rats; Rats, Sprague-Dawley; Receptors, Drug; Reflex; Spinal Cord