resiniferatoxin and Edema

Capsaicin-sensitive afferents have complex regulatory functions in the joints orchestrated via neuropeptides. This study aimed to determine their role in the collagen-antibody induced rheumatoid arthritis model. Capsaicin-sensitive nerves were defunctionalized by the capsaicin receptor agonist resiniferatoxin in C57Bl/6 mice. Arthritis was induced by the ArithroMab antibody cocktail and adjuvant. Arthritis was monitored by measuring body weight, joint edema by plethysmometry, arthritis severity by clinical scoring, mechanonociceptive threshold by plantar esthesiometry, thermonociceptive threshold by hot plate, cold tolerance by paw withdrawal latency from 0 °C water. Grasping ability was determined by the wire-grid grip test. Bone structure was evaluated by in vivo micro-CT and histology. Arthritic animals developed a modest joint edema, mechanical and cold hyperalgesia, weight loss, and a diminished grasping function, while thermal hyperalgesia is absent in the model. Desensitised mice displayed reduced arthritis severity, edema, and mechanical hyperalgesia, however, cold hyperalgesia was significantly greater in this group. Arthritic controls displayed a transient decrease of bone volume and an increased porosity, while bone density and trabecularity increased in desensitised mice. The activation of capsaicin-sensitive afferents increases joint inflammation and mechanical hyperalgesia, but decreases cold allodynia. It also affects inflammatory bone structural changes by promoting bone resorption.

Topics: Animals; Ankle Joint; Antibodies; Arthritis, Experimental; Body Weight; Capsaicin; Disease Models, Animal; Diterpenes; Edema; Hyperalgesia; Male; Mice; Mice, Inbred C57BL; Neurons, Afferent; Severity of Illness Index; X-Ray Microtomography

The K/BxN serum-transfer arthritis is a widely-used translational mouse model of rheumatoid arthritis, in which the immunological components have thoroughly been investigated. In contrast, little is known about the role of sensory neural factors and the complexity of neuro-immune interactions. Therefore, we analyzed the involvement of capsaicin-sensitive peptidergic sensory nerves in autoantibody-induced arthritis with integrative methodology.. Arthritogenic K/BxN or control serum was injected to non-pretreated mice or resiniferatoxin (RTX)-pretreated animals where capsaicin-sensitive nerves were inactivated. Edema, touch sensitivity, noxious heat threshold, joint function, body weight and clinical arthritis severity scores were determined repeatedly throughout two weeks. Micro-CT and in vivo optical imaging to determine matrix-metalloproteinase (MMP) and neutrophil-derived myeloperoxidase (MPO) activities, semiquantitative histopathological scoring and radioimmunoassay to measure somatostatin in the joint homogenates were also performed.. In RTX-pretreated mice, the autoantibody-induced joint swelling, arthritis severity score, MMP and MPO activities, as well as histopathological alterations were significantly greater compared to non-pretreated animals. Self-control quantification of the bone mass revealed decreased values in intact female mice, but significantly greater arthritis-induced pathological bone formation after RTX-pretreatment. In contrast, mechanical hyperalgesia from day 10 was smaller after inactivating capsaicin-sensitive afferents. Although thermal hyperalgesia did not develop, noxious heat threshold was significantly higher following RTX pretreatment. Somatostatin-like immunoreactivity elevated in the tibiotarsal joints in non-pretreated, which was significantly less in RTX-pretreated mice.. Although capsaicin-sensitive sensory nerves mediate mechanical hyperalgesia in the later phase of autoantibody-induced chronic arthritis, they play important anti-inflammatory roles at least partially through somatostatin release.

Topics: Animals; Arthritis, Experimental; Arthritis, Rheumatoid; Capsaicin; Disease Models, Animal; Diterpenes; Edema; Hindlimb; Hyperalgesia; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Nociceptors; Pain Threshold; Peroxidase; Reactive Oxygen Species; Sensory System Agents; Somatostatin; Tarsus, Animal; TRPV Cation Channels; X-Ray Microtomography

Neural cross talk between visceral organs may play a role in mediating inflammation and pain remote from the site of the insult. We hypothesized such a cross talk exists between the duodenum and pancreas, and further it induces pancreatitis in response to intraduodenal toxins. A dichotomous spinal innervation serving both the duodenum and pancreas was examined, and splanchnic nerve responses to mechanical stimulation of these organs were detected. This pathway was then excited on the duodenal side by exposure to ethanol followed by luminal mustard oil to activate transient receptor potential subfamily A, member 1 (TRPA1). Ninety minutes later, pancreatic inflammation was examined. Ablation of duodenal afferents by resiniferatoxin (RTX) or blocking TRPA1 by Chembridge (CHEM)-5861528 was used to further investigate the duodeno-pancreatic neural reflex via TRPA1. ~40% of dorsal root ganglia (DRG) from the spinal cord originated from both duodenum and pancreas via dichotomous peripheral branches; ~50% splanchnic nerve single units responded to mechanical stimulation of both organs. Ethanol sensitized TRPA1 currents in cultured DRG neurons. Pancreatic edema and myeloperoxidase activity significantly increased after intraduodenal ethanol followed by mustard oil (but not capsaicin) but significantly decreased after ablation of duodenal afferents by using RTX or blocking TRPA1 by CHEM-5861528. We found the existence of a neural cross talk between the duodenum and pancreas that can promote acute pancreatitis in response to intraduodenal chemicals. It also proves a previously unexamined mechanism by which alcohol can induce pancreatitis, which is novel both in terms of the site (duodenum), process (neurogenic), and receptor (TRPA1).

Topics: Acute Disease; Animals; Capsaicin; Central Nervous System Depressants; Diterpenes; Duodenum; Edema; Ethanol; Fluorescent Antibody Technique; Ganglia, Spinal; Male; Muscle Contraction; Pancreas; Pancreatitis; Patch-Clamp Techniques; Physical Stimulation; Rats; Rats, Sprague-Dawley; Reflex; Sensory Receptor Cells; Splanchnic Nerves; Stomach; TRPA1 Cation Channel; TRPC Cation Channels; TRPV Cation Channels

The transient receptor potential vanilloid 1 (TRPV1) receptor is relevant to the perception of noxious information and has been studied as a therapeutic target for the development of new analgesics. The goal of this study was to perform in vivo and in vitro screens to identify novel, efficacious, and safe TRPV1 antagonists isolated from leaves of the medicinal plant Vernonia tweedieana Baker. All of the fractions and the hydroalcoholic extract produced antinociception in mice during the capsaicin test, but the dichloromethane fraction also had antioedematogenic effect. Among the compounds isolated from the dichloromethane fraction, only α-spinasterol reduced the nociception and edema induced by capsaicin injection. Moreover, α-spinasterol demonstrated good oral absorption and high penetration into the brain and spinal cord of mice. α-Spinasterol was able to displace [3H]resiniferatoxin binding and diminish calcium influx mediated by capsaicin. Oral administration of the dichloromethane fraction and α-spinasterol also produced antinociceptive effect in the noxious heat-induced nociception test; however, they did not change the mechanical threshold of naive mice. The treatment with α-spinasterol did not produce antinociceptive effect in mice systemically pretreated with resiniferatoxin. In addition, α-spinasterol and the dichloromethane fraction reduced the edema, mechanical, and heat hyperalgesia elicited by complete Freund's adjuvant paw injection. The dichloromethane fraction and α-spinasterol did not affect body temperature or locomotor activity. In conclusion, α-spinasterol is a novel efficacious and safe antagonist of the TRPV1 receptor with antinociceptive effect.

Topics: Analgesics; Animals; Binding, Competitive; Body Temperature; Calcium; Capsaicin; Chromatography, High Pressure Liquid; Diterpenes; Edema; Freund's Adjuvant; Hot Temperature; Male; Mice; Nociceptors; Pain; Pain Measurement; Plant Extracts; Plant Leaves; Stigmasterol; Tissue Distribution; TRPV Cation Channels; Vernonia

Gout is characterized by the deposition of monosodium urate (MSU) crystals. Despite being one of the most painful forms of arthritis, gout and the mechanisms responsible for its acute attacks are poorly understood. In the present study, we found that MSU caused dose-related nociception (ED(50) [ie, the necessary dose of MSU to elicit 50% of the response relative to the control value]=0.04 [95% confidence interval 0.01-0.11]mg/paw) and edema (ED(50)=0.08 [95% confidence interval 0.04-0.16]mg/paw) when injected into the hind paw of rats. Treatment with the selective TRPV1 receptor (also known as capsaicin receptor and vanilloid receptor-1) antagonists SB366791 or AMG9810 largely prevented nociceptive and edematogenic responses to MSU. Moreover, the desensitization of capsaicin-sensitive afferent fibers as well as pretreatment with the tachykinin NK(1) receptor antagonist RP 67580 also significantly prevented MSU-induced nociception and edema. Once MSU was found to induce mast cell stimulation, we investigated the participation of these cells on MSU effects. Prior degranulation of mast cells by repeated treatment with the compound 48/80 decreased MSU-induced nociception and edema or histamine and serotonin levels in the injected tissue. Moreover, pretreatment with the mast cell membrane stabilizer cromolyn effectively prevented nociceptive and edematogenic responses to MSU. MSU induced a release of histamine, serotonin, and tryptase in the injected tissue, confirming mast cell degranulation. Furthermore, the antagonism of histaminergic H1 and serotoninergic receptors decreased the edema, but not the nociception of MSU. Finally, the prevention of the tryptase activity was capable of largely reducing both MSU-induced nociception and edema. Collectively, the present findings demonstrate that MSU produces nociceptive and edematogenic responses mediated by TRPV1 receptor activation and mast cell degranulation.

Topics: Acrylamides; Anilides; Animals; Anti-Allergic Agents; Anti-Asthmatic Agents; Antioxidants; Bridged Bicyclo Compounds, Heterocyclic; Capsaicin; Cinnamates; Cromolyn Sodium; Disease Models, Animal; Diterpenes; Edema; Gabexate; Histamine; Male; Mast Cells; Methysergide; Pain; Promethazine; Prostaglandin-Endoperoxide Synthases; Protein Binding; Rats; Rats, Wistar; Serine Proteinase Inhibitors; Serotonin; Serotonin Antagonists; Tritium; TRPV Cation Channels; Uric Acid

The role of capsaicin-sensitive primary afferent fibers in rat pain-related behaviors and paw edema induced by scorpion Buthus martensi Karch (BmK) venom was investigated in this study. It was found that functional depletion of capsaicin-sensitive primary afferent fibers with a single systemic injection of resiniferatoxin (RTX) dramatically decreased spontaneous nociceptive behaviors, prevented the development of primary mechanical and thermal hyperalgesia as well as mirror-image mechanical hyperalgesia. RTX treatment significantly attenuated BmK venom-induced c-Fos expression in all laminaes of bilateral L4-L5 lumbar spinal cord, especially in superficial laminaes. Moreover, RTX treatment markedly reduced the early paw edema induced by BmK venom. Thus, the results indicate that capsaicin-sensitive primary afferent fibers play a critical role in various pain-related behaviors and paw edema induced by BmK venom in rats.

Topics: Animals; Capsaicin; Diterpenes; Edema; Hindlimb; Hyperalgesia; Immunohistochemistry; Neurons, Afferent; Nociceptors; Pain; Pain Threshold; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Scorpion Venoms; Spinal Cord

Resiniferatoxin (RTX) is an ultrapotent capsaicin analog that binds to the transient receptor potential channel, vanilloid subfamily member 1 (TRPV1). There is a large body of evidence supporting a role for TRPV1 in noxious-mediated and inflammatory hyperalgesic responses. In this study, we evaluated low, graded, doses of perineural RTX as a method for regional pain control. We hypothesized that this approach can provide long-term, but reversible, blockade of a portion of nociceptive afferent fibers within peripheral nerves when given at a site remote from the neuronal perikarya in the dorsal root ganglia. Following perineural RTX application to the sciatic nerve, we demonstrated a significant inhibition of inflammatory nociception that was dose- and time-dependent. At the same time, treated animals maintained normal proprioceptive sensations and motor control, and other nociceptive responses were largely unaffected. Using a range of mechanical and thermal algesic tests, we found that the most sensitive measure following perineural RTX administration was inhibition of inflammatory hyperalgesia. Recovery studies showed that physiologic sensory function could return as early as two weeks post-RTX treatment, however, immunohistochemical examination of the DRG revealed a partial, but significant reduction in the number of the TRPV1-positive neurons. We propose that this method could represent a beneficial treatment for a range of chronic pain problems, including neuropathic and inflammatory pain not responding to other therapies.

Topics: Administration, Cutaneous; Animals; Behavior, Animal; Capsaicin; Diterpenes; Dose-Response Relationship, Drug; Edema; Electric Stimulation; Ganglia, Spinal; Hot Temperature; Hyperalgesia; Inflammation; Male; Neurogenic Inflammation; Peripheral Nerves; Rats; Rats, Sprague-Dawley; Rotarod Performance Test; Sciatic Nerve; Time Factors; TRPV Cation Channels

Inhibitory actions of pituitary adenylate cyclase activating polypeptide (PACAP) have been described on cellular/vascular inflammatory components, but there are few data concerning its role in neurogenic inflammation. In this study we measured PACAP-like immunoreactivity with radioimmunoassay in the rat plasma and showed a two-fold elevation in response to systemic stimulation of capsaicin-sensitive sensory nerves by resiniferatoxin, but not after local excitation of cutaneous afferents. Neurogenic plasma extravasation in the plantar skin induced by intraplantar capsaicin or resiniferatoxin, as well as carrageenan-induced paw edema were significantly diminished by intraperitoneal PACAP-38. In summary, these results demonstrate that PACAP is released from activated capsaicin-sensitive afferents into the systemic circulation. It diminishes acute pure neurogenic and mixed-type inflammatory reactions via inhibiting pro-inflammatory mediator release and/or by acting at post-junctional targets on the vascular endothelium.

Topics: Acute Disease; Animals; Capsaicin; Carrageenan; Diterpenes; Edema; Inflammation; Injections, Intraperitoneal; Male; Mass Spectrometry; Neurogenic Inflammation; Pituitary Adenylate Cyclase-Activating Polypeptide; Radioimmunoassay; Rats; Rats, Wistar; TRPV Cation Channels

The participation of sensory neurons and transient receptor potential vanilloid 1 (TRPV1) receptors in phorbol 12-myristate 13-acetate (PMA)-induced nerve-sensitizing effect was examined.. PMA dissolved in acetone and acetone were applied to the ears of TRPV1 receptor knockout and wild-type mice. Different groups of animals received ibuprofen, anti-interleukin-1 beta (IL-1beta) antibody, resiniferatoxin (RTX) or capsaicin pretreatment. Ear thickness, myeloperoxidase activity and IL-1beta content of the ears were determined. Histological evaluation was performed.. PMA exerted potentiating action on contralateral acetone-induced ear oedema, which was inhibited by ibuprofen, topical capsaicin desensitization of the acetone-treated ear as well as by systemic RTX pretreatment. Neither the lack of TRPV1 receptors nor anti-IL-1beta antibody prevented sensitizing effect.. The TRPV1 receptor-independent potentiating action of PMA on contralateral acetone-induced ear oedema is mediated via capsaicin-sensitive afferents and prostanoids are involved. IL-1beta is not essential in this process.

Topics: Acetone; Administration, Cutaneous; Afferent Pathways; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antibodies; Capsaicin; Diterpenes; Drug Synergism; Ear; Edema; Ibuprofen; Interleukin-1beta; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peroxidase; Sensory Receptor Cells; Tetradecanoylphorbol Acetate; TRPV Cation Channels

We previously demonstrated that somatostatin (SOM) released from the activated peripheral terminals of capsaicin-sensitive primary sensory neurons inhibits acute inflammation and nociception. This study was undertaken to examine this systemic "sensocrine" function of neuronally derived somatostatin in chronic inflammation in the Freund's complete adjuvant (CFA)-induced arthritis model.. Arthritis of the tibiotarsal joint of Lewis rats was evoked by subcutaneous injection of CFA into the left hind paw and the tail root. For 3 weeks, the volume of the paws was measured by plethysmometry, and the mechanonociceptive thresholds were measured by esthesiometry. Plasma concentrations of SOM were determined by radioimmunoassay, and histologic studies of the joints were performed. To impair the function of capsaicin-sensitive afferents, the capsaicin receptor (VR1/TRPV1) agonist resiniferatoxin (RTX) was injected subcutaneously (30, 70, and 100 microg/kg on 3 subsequent days) 7 days before CFA administration. The SOM receptor antagonist cyclosomatostatin (c-SOM; 20 microg/kg) or, in another group, the synthetic heptapeptide agonist TT-232 (2 x 50-400 microg/kg) was administered intraperitoneally every day.. RTX pretreatment or c-SOM injection significantly increased edema and mechanical hyperalgesia of both CFA-treated and contralateral paws. The histologic score based on synovial thickening, cell infiltration, cartilage destruction, and bone erosion was also significantly higher both in the RTX- and the c-SOM-injected groups. These parameters were dose-dependently decreased by TT-232. Plasma SOM-like immunoreactivity increased 4-fold on the twenty-first day, and was inhibited by RTX pretreatment, as well as by daily administration of TT-232.. Our data suggest that SOM released into the circulation from capsaicin-sensitive afferents in response to prolonged activation exerts systemic antiinflammatory and analgesic effects. TT-232 can open new perspectives in the treatment of chronic arthritis.

Topics: Analgesics; Animals; Anti-Inflammatory Agents; Arthritis, Experimental; Chronic Disease; Disease Models, Animal; Diterpenes; Edema; Freund's Adjuvant; Hindlimb; Male; Peptides, Cyclic; Rats; Rats, Inbred Lew; Receptors, Drug; Sensory Receptor Cells; Somatostatin

A number of phorboid 20-homovanillates were prepared by condensation of phorbol 12,13-diesters and 12-dehydrophorbol 13-esters with Mem-homovanillic acid followed by removal of the protecting group with SnCl4 in THF. These compounds were evaluated for their ability to inhibit [3H]resiniferatoxin (RTX) binding to rat spinal cord membranes. Compounds bearing a lipophilic ester group on ring C were considerably active, but a surprising tolerance of the vanilloid receptor toward the location and the orientation of this ester group was disclosed. Unexpectedly, these ligands could also diminish, to a variable degree, the positive cooperativity which characterizes RTX binding to the vanilloid receptor. Phorbol 12-phenylacetate 13-acetate 20-homovanillate (PPAHV, 6a), a compound which abolished binding cooperativity, was further tested in a variety of in vivo assay used to characterize vanilloid-like activity. PPAHV showed only a marginal pungency and failed to induce a measurable hypothermia response at doses (up to 200 mg/kg) at which it effectively desensitized against neurogenic inflammation. These data suggest that the peculiar binding behavior of these ligands might be associated with a distinct spectrum of biological activity.

Topics: Animals; Body Temperature; Diterpenes; Edema; Homovanillic Acid; Magnetic Resonance Spectroscopy; Mass Spectrometry; Membrane Proteins; Molecular Structure; Phorbol Esters; Protein Binding; Rats; Receptors, Drug; Spinal Cord

All tumor-promoting phorbol esters induce inflammation in mouse skin. The correlation between promoting and inflammatory activities is only partial, however, indicating that only some events in inflammation may be closely coupled to the process of tumor promotion. Resiniferatoxin (RTX), an extremely inflammatory phorbol-related diterpene, acts as an ultrapotent analog of capsaicin to stimulate and then to block the neurogenic inflammatory pathway. In CD-1 mice, we have used pretreatment with RTX to show that the erythema and edema responses to phorbol and 12-deoxyphorbol esters in significant part involve this neurogenic inflammatory pathway. We report here that mouse strains with differing sensitivities to phorbol-ester-induced promotion displayed marked differences in the effect of pretreating with RTX on the edema response following phorbol-12-myristate-13-acetate (PMA) application. In the highly promotion-sensitive SENCAR mouse, RTX pretreatment had little inhibitory effect; the edema response to PMA was similar with or without RTX pretreatment 6 h before PMA application. On the other hand, in C57BL/6J mice, which are resistant to promotion by phorbol esters under the usual protocols, the edema response to PMA was totally eliminated by RTX pretreatment during the first 8 h after PMA administration. DBA/2J mice, which are similar to CD-1 mice in their susceptibility to PMA promotion, responded similarly to CD-1: the edema response was blocked partially by RTX pretreatment during the early phase (up to 8 h) of inflammation. Our results suggest that the RTX-resistant component of PMA-induced edema may correlate better with the sensitivity to promoting action than does the overall inflammatory response.

Topics: Animals; Carcinogens; Diterpenes; Edema; Female; Inflammation; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Mice, Inbred Strains; Tetradecanoylphorbol Acetate; Time Factors