Topical treatment with a transient receptor potential ankyrin 1 (TRPA1) antagonist reduced nociception and inflammation in a thermal lesion model in rats.

Thermal injury promotes tissue inflammation and pain, which is difficult to control. Different peripheral mechanisms seem to be involved in burn pain, such as free radical-induced damage, but further study is still needed to understand how oxidant substances induced nociceptor sensitization. The transient receptor potential ankyrin 1 (TRPA1) is an ion channel activated by oxidants substances, and it could be sensitized after tissue inflammation. This study evaluated the TRPA1 involvement in nociception and inflammation produced by a thermal injury model. Male Wistar rats were used. The concentration of the TRPA1 antagonist (HC-030031, 0.05%) on base cream was chosen using allyl isothiocyanate intraplantar test. Then, the base cream containing HC-030031 was tested on the thermal injury model (induced by warm water immersion of hind paw, under anesthesia), and silver sulfadiazine (1%) was used as a positive control. Cream treatments on the hind paw were done daily (200 mg/paw) for 6 days after thermal injury. Also, nociception (static and dynamic mechanical allodynia, heat allodynia, and spontaneous pain) or edema were evaluated. On day 6, inflammatory and oxidative parameters were assessed. The base cream containing HC-030031 produced antinociceptive and anti-inflammatory effects (reduced the edema and inflammatory cells infiltration) and decreased the levels of hydrogen peroxide, or superoxide dismutase and NADPH oxidase activities after thermal injury. Thus, this study showed the involvement of the TRPA1 receptor in the nociception and inflammation caused by thermal injury and suggested that TRPA1 antagonists might be useful as novel treatments for pain and inflammation by topical application.

TRPA1 receptor stimulation by hydrogen peroxide is critical to trigger hyperalgesia and inflammation in a model of acute gout.

Acute gout attacks produce severe joint pain and inflammation associated with monosodium urate (MSU) crystals leading to oxidative stress production. The transient potential receptor ankyrin 1 (TRPA1) is expressed by a subpopulation of peptidergic nociceptors and, via its activation by endogenous reactive oxygen species, including hydrogen peroxide (H2O2), contributes to pain and neurogenic inflammation. The aim of this study was to investigate the role of TRPA1 in hyperalgesia and inflammation in a model of acute gout attack in rodents. Inflammatory parameters and mechanical hyperalgesia were measured in male Wistar rats and in wild-type (Trpa1(+/+)) or TRPA1-deficient (Trpa1(-/-)) male mice. Animals received intra-articular (ia, ankle) injection of MSU. The role of TRPA1 was assessed by receptor antagonism, gene deletion or expression, sensory fiber defunctionalization, and calcitonin gene-related peptide (CGRP) release. We found that nociceptor defunctionalization, TRPA1 antagonist treatment (via ia or oral administration), and Trpa1 gene ablation abated hyperalgesia and inflammatory responses (edema, H2O2 generation, interleukin-1ß release, and neutrophil infiltration) induced by ia MSU injection. In addition, we showed that MSU evoked generation of H2O2 in synovial tissue, which stimulated TRPA1 producing CGRP release and plasma protein extravasation. The MSU-elicited responses were also reduced by the H2O2-detoxifying enzyme catalase and the reducing agent dithiothreitol. TRPA1 activation by MSU challenge-generated H2O2 mediates the entire inflammatory response in an acute gout attack rodent model, thus strengthening the role of the TRPA1 receptor and H2O2 production as potential targets for treatment of acute gout attacks.

Anti-inflammatory and antioxidant effects of Aloe saponaria Haw in a model of UVB-induced paw sunburn in rats.

Ultraviolet B (UVB) irradiation mainly affects biological tissues by inducing an increase in reactive oxygen species (ROS) production which leads to deleterious outcomes for the skin, including pain and inflammation. As a protective strategy, many studies have focused on the use of natural products. The aim of this study was to investigate the effects of Aloe saponaria on nociceptive, inflammatory, and oxidative parameters in a model of UVB-induced sunburn in adult male Wistar rats. Sunburned animals were topically treated with vehicle (base cream), 1% silver sulfadiazine (positive control) or A. saponaria (10%) once a day for 6days. UVB-induced nociception (allodynia and hyperalgesia), inflammation (edema and leukocyte infiltration) and oxidative stress (increases in H2O2, protein carbonyl levels and lipid peroxidation and a decrease in non protein thiol content) were reduced by both A. saponaria and sulfadiazine topical treatment. Furthermore, A. saponaria or its constituents aloin and rutin reduced the oxidative stress induced by H2O2 in skin homogenates in vitro. Our results demonstrate that topical A. saponaria treatment displayed anti-nociceptive and anti-inflammatory effects in a UVB-induced sunburn model, and these effects seem to be related to its antioxidant components.

Effects of Campomanesia xanthocarpa on inflammatory processes, oxidative stress, endothelial dysfunction and lipid biomarkers in hypercholesterolemic individuals.

In Brazil, the edible plant Campomanesia xanthocarpa Berg. (Myrtaceae), popularly known as "guavirova," has been studied in hypercholesterolemic individuals. The present work investigated the effects of C. xanthocarpa on inflammatory processes, oxidative stress, endothelial dysfunction and lipid biomarkers in hypercholesterolemic individuals. A total of 156 individuals were selected in a double-blind fashion and randomly divided into two groups in accordance with the intervals used in the criteria for hypercholesterolemia: individuals with total cholesterol (TC) levels between 200 and 240 mg/dL (undesirable level individuals - UL) and individuals with TC levels >240 mg/dL (hypercholesterolemic individuals - HL). Both groups had a control group (CG), which received placebo treatment, an encapsulated excipient group (lactose) and an experimental group that received 500 mg (EG 500), 750 mg (EG 750) or 1000 mg (EG 1000) of encapsulated C. xanthocarpa. The inflammatory processes (high-sensitivity C-reactive protein - hs-CRP), oxidative stress (advanced oxidation protein products-AOPPs; ischemia-modified albumin-IMA), endothelial dysfunction (nitric oxide - NOx) and biochemical (TC, triglycerides, high-density lipoprotein - HDL, low-density lipoproteins - LDL, and very low-density lipoprotein - VLDL) parameters were measured before and 90 days after the initiation of treatment. A significant decrease in TC and LDL levels was observed in HL individuals from the EG 500 group (reduction of 29 ± 3% and 41 ± 5% to levels before treatment) compared to the CG group individuals. A significant reduction in oxidative stress and inflammatory process components (reduction of 52 ± 11% in AOPPs, 32 ± 10% in IMA and 57 ± 7% in hs-CRP) and a significant increase in NOx (increase of 84 ± 27%) was observed in HL individuals in the EG 1000 group when compared to the CG group individuals. Treatment with encapsulated C. xanthocarpa reduced blood TC and LDL levels in hypercholesterolemic individuals. In addition to its effect on cholesterol levels, this plant reduced oxidative stress in hypercholesterolemic individuals and improved the levels of NOx.

Participation of the TRPV1 receptor in the development of acute gout attacks.

OBJECTIVE: The aim of the present study was to investigate the participation of TRPV1 in an acute gout attack model. METHODS: Experiments were conducted to evaluate the participation of TRPV1 in the nociceptive and inflammatory responses (oedema, plasma extravasation, leucocyte infiltration and also IL-1ß production) triggered by IA (ankle) administration of monosodium urate (MSU) in rats using selective antagonist TRPV1 receptor, defunctionalization of sensory fibres and increased immunoreactivity. We have also analysed the inflammatory response. The participation of mast cells in the MSU-induced nociception and inflammation was evaluated using a mast cell stabilizer and a mast cell degranulator compound. RESULTS: We observed that MSU (1.25 mg/site) injected into the rat ankle joint elicited ongoing pain-like behaviour, hyperalgesia, allodynia and articular oedema as well as plasma extravasation, leucocyte infiltration and IL-1ß production in lavage fluid. All of these events were inhibited by the co-administration of the selective TRPV1 receptor antagonist SB366791 (10 nmol/site). MSU crystals also increased the immunoreactivity of the TRPV1 receptor in the articular tissue of injected animals. Furthermore, the defunctionalization of TRPV1-positive sensory neurons also significantly reduced MSU-induced ongoing pain-like behaviour, hyperalgesia and oedema. CONCLUSION: Thus we demonstrate that TRPV1 acts on sensory neurons and plays a relevant role in the nociception and inflammation induced by IA MSU, indicating it as a potential target to treat acute gout attacks.

Antiinflammatory effects of Viola tricolor gel in a model of sunburn in rats and the gel stability study.

ETHNOPHARMACOLOGICAL RELEVANCE: Viola tricolor, popularly known as heartsease has been empirically used in several skin disorders, including burns. AIM OF THE STUDY: The objective of this study was investigate the antinociceptive and antiinflammatory effect of a gel containing extract of Viola tricolor flowers on thermal burn induced by UVB irradiation and to perform gel stability study. METHODS: The antinociceptive and antiinflammatory effect were evaluated by static and dynamic mechanical allodynia model, paw edema, and neutrophilic cell infiltration. Metabolites compounds were quantified by HPLC. The gel stability study was performed analyzing organoleptical aspects, besides pH, viscosity, and quantification of rutin by HPLC. RESULTS: In the results were evidenced changes in threshold in statical and dynamic mechanical allodynia (I(max)=100 ± 10% and 49 ± 10%, respectively), paw edema (I(max)=61 ± 6%), and myeloperoxidase activity (I(max)=89 ± 5%). Such effects may be attributed, in part, to rutin, salicylic and chlorogenic acids, and others compounds found in this species. No important changes were detected in the stability study, in all aspects analyzed in temperature below 25 °C. CONCLUSION: These findings suggest that Viola tricolor gel has an antinociceptive and antiinflammatory effect in the ultraviolet-B-induced burn, since maintain the temperature below 25 °C.

Antinociceptive and anti-inflammatory effects of Aloe saponaria Haw on thermal injury in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: In Brazil, the plant Aloe saponaria Haw, popularly known as "babosa pintadinha", has been empirically used for its potential effect on thermal injury. Because there are no scientific data confirming its popular use, the aim of the present study was to investigate the effects of Aloe saponaria on nociceptive and inflammatory parameters in a rat model of thermal injury. MATERIALS AND METHODS: Adult male Wistar rats were subjected to a thermal injury or sham procedure (immersion in water at 70 or 37°C, respectively, for 5 or 8s). Burned animals were topically treated with vehicle (base cream), sulfadiazine 1% (positive control) or Aloe saponaria cream (0.3%-30%) once a day for 2 or 6 days. Each day, 30min before the treatment, we measured nociceptive (static and dynamic mechanical allodynia, thermal allodynia and spontaneous pain) and inflammatory (paw edema) parameters. Moreover, enzymatic indicators of leukocyte infiltration into burned tissue were also determined 2 or 6 days after the thermal injury. RESULTS: The thermal injury (fist and second-degree) procedure, but not the sham procedure, induced nociception and inflammation from 1 to 6 days after the injury. The topical treatment with Aloe saponaria cream (10%) reduced nociceptive behaviors from day 1 to 6 (peak at day 2), edema at days 5 and 6 (peak at day 6) and myeloperoxidase, N-acetyl-glucosaminidase and eosinoperoxidase activities at day 6. The antinociceptive and anti-inflammatory effects of Aloe saponaria were obtained with doses of 3%-30%, with maximal inhibition obtained with a dose of 10% (reductions of 39±9%, 41±9%, 31±7%, 83±7% and 23±2% for static and dynamic mechanical allodynia, thermal allodynia, spontaneous pain and paw edema, respectively). CONCLUSION: Our results demonstrate that topically applied Aloe saponaria presented antinociceptive and anti-inflammatory effects in rats subjected to a thermal injury, which supports its traditional use for burn injuries.

Contribution of peripheral vanilloid receptor to the nociception induced by injection of spermine in mice.

Polyamines (putrescine, spermidine and spermine) are important endogenous regulators of ion channels, such as vanilloid (TRPV1), glutamatergic (NMDA or AMPA/kainate) and acid-sensitive (ASIC) receptors. In the present study, we have investigated the possible nociceptive effect induced by polyamines and the mechanisms involved in this nociception in vivo. The subcutaneous (s.c.) injection of capsaicin (as positive control), spermine, spermidine or putrescine produced nociception with ED(50) of 0.16 (0.07-0.39)nmol/paw, 0.4 (0.2-0.7) µmol/paw, 0.3 (0.1-0.9) µmol/paw and 3.2 (0.9-11.5) µmol/paw, respectively. The antagonists of NMDA (MK801, 1 nmol/paw), AMPA/kainate (DNQX, 1 nmol/paw) or ASIC receptors (amiloride, 100 nmol/paw) failed to reduce the spermine-trigged nociception. However, the TRPV1 antagonists capsazepine or SB366791 (1 nmol/paw) reduced spermine-induced nociception, with inhibition of 81 ± 10 and 68 ± 9%, respectively. The previous desensitization with resiniferatoxin (RTX) largely reduced the spermine-induced nociception and TRPV1 expression in the sciatic nerve, with reductions of 82 ± 9% and 67 ± 11%, respectively. Furthermore, the combination of spermine (100 nmol/paw) and RTX (0.005 fmol/paw), in doses which alone were not capable of inducing nociception, produced nociceptive behaviors. Moreover, different concentrations of spermine (3-300 µM) enhanced the specific binding of [(3)H]-RTX to TRPV1 receptor. Altogether, polyamines produce spontaneous nociceptive effect through the stimulation of TRPV1, but not of ionotropic glutamate or ASIC receptors.

Effects of Campomanesia xanthocarpa on biochemical, hematological and oxidative stress parameters in hypercholesterolemic patients.

ETHNOPHARMACOLOGICAL RELEVANCE: In Southern Brazil, the plant Campomanesia xanthocarpa Berg. (Myrtaceae), popularly known as "guavirova", has been empirically used for its potential effect in reducing blood cholesterol levels. AIM OF THE STUDY: Since there are no scientific data confirming its popular use, the aim of the present study was to investigate the effect of Campomanesia xanthocarpa on biochemical, hematological, anthropometrical and oxidative stress parameters in hypercholesterolemic patients. MATERIALS AND METHODS: Thirty three patients were selected according to total cholesterol (TC) levels: 200-240 mg/dL, undesirable level (UL), and >240 mg/dL, hypercholesterolemic level (HL). UL or HL patients were randomly divided into control group (CG), which received placebo capsules, and experimental group 250 (EG 250) or 500 (EG 500), which received either 250 or 500 mg of encapsulated Campomanesia xanthocarpa. All groups received a cholesterol restriction diet and capsules once a day. The biochemical (TC, triglycerides, HDL, LDL and VLDL), hematological (hematocrit and hemoglobin), anthropometrical (weight and abdominal circumference) and oxidative stress (protein carbonyl) parameters were measured before, 45 and 90 days after the treatment started. RESULTS: There was no alteration on biochemical, hematological, anthropometric or oxidative stress parameters in UL patients of all groups. However, a significant decrease in TC and LDL levels was observed in HL patients from EG 500 group (reduction of 28+/-3% and 45+/-4% to levels before treatment) in relation to CG group patients (reduction of 12+/-2% and 29+/-4%). Moreover, a significant reduction in oxidative stress was observed in HL patients of EG 250 (51+/-12%) and EG 500 groups (34+/-18%) when compared to levels before treatment. A positive correlation between plasma oxidative stress PC and TC levels was observed. Finally, we found that Campomanesia xanthocarpa extract possesses anti-oxidant properties and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitory activity in vitro. CONCLUSION: Confirming its popular use, the treatment with Campomanesia xanthocarpa encapsulated reduced blood TC and LDL levels in hypercholesterolemic patients.