Complex Regional Pain Syndrome Type I: Evidence for the CB1 and CB2 Receptors Immunocontent and Beneficial Effect of Local Administration of Cannabidiol in Mice.

Introduction: Complex regional pain syndrome type I (CRPS-I) is a debilitating neuropathic painful condition associated with allodynia, hyperalgesia, sudomotor and/or vasomotor dysfunctions, turning investigation of its pathophysiology and new therapeutic strategies into an essential topic. We aim to investigate the impact of ischemia/reperfusion injury on the immunocontent of CB1 and CB2 cannabinoid receptor isoforms in the paws of mice submitted to a chronic postischemia pain (CPIP) model and the effects of local administration of cannabidiol (CBD) on mechanical hyperalgesia. Methods: Female Swiss mice, 30-35 g, were submitted to the CPIP model on the right hind paw. Skin and muscle samples were removed at different periods for western blot analysis. Results: No changes in the immunocontent of CB1 and CB2 receptors in paw muscle tissues after ischemia-reperfusion were observed. CBD promoted an antihyperalgesic effect in both phases. AM281 reversed the effect of CBD, whereas ruthenium red abolished the late phase. Conclusion: Our results point to the possible beneficial effects of local administration of CBD in modulating CRPS-I in humans. As possible targets for CBD antihyperalgesia in this model, the contribution of cannabinoid receptor CB1, in addition to TRPM8 is suggested.

The Inflammatory Role of Pro-Resolving Mediators in Endometriosis: An Integrative Review.

The pathogenesis of endometriosis is still controversial, although it is known that the inflammatory immune response plays a critical role in this process. The resolution of inflammation is an active process where the activation of endogenous factors allows the host tissue to maintain homeostasis. The mechanisms by which pro-resolving mediators (PRM) act in endometriosis are still little explored. Thus, this integrative review aims to synthesize the available content regarding the role of PRM in endometriosis. Experimental and in vitro studies with Lipoxin A4 demonstrate a potential inhibitory effect on endometrial lesions' progression, attenuating pro-inflammatory and angiogenic signals, inhibiting proliferative and invasive action suppressing intracellular signaling induced by cytokines and estradiol, mainly through the FPR2/ALX. Investigations with Resolvin D1 demonstrated the inhibition of endometrial lesions and decreased pro-inflammatory factors. Annexin A1 is expressed in the endometrium and is specifically present in women with endometriosis, although the available studies are still inconsistent. Thus, we believe there is a gap in knowledge regarding the PRM pathways in patients with endometriosis. It is important to note that these substances' therapeutic potential is evident since the immune and abnormal inflammatory responses play an essential role in endometriosis development and progression.

Macroscopic, biochemical and hystological evaluation of topical anti-inflammatory activity of Casearia sylvestris (Flacourtiaceae) in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Inflammatory skin diseases presents high prevalence and lack of alternatives that can be used for self-care by the population. Casearia sylvestris is a plant used topically in different communities in Brazil, to treat wounds or promote cutaneous healing. To evaluate the topical anti-inflammatory activity for the crude hydroalcoholic extract of Casearia sylvestris (HCE-CS) in the models of single or multiple administration of chroton oil to induce ear edema in mice. MATERIALS AND METHODS: Experimental study using male Swiss mice (25-35g) kept under constant conditions in the Laboratory of Experimental Neuroscience (LaNEx)-UNISUL. Edema was induced in both models, respectively, by the single or multiple application of croton oil (CO, 2.5%, in 20 µl) on the external surface of the ear. The different groups of animals (n = 8) received different treatments: vehicle, dexamethasone (DEXA) or different doses of HCE-CS. Edema was evaluated macroscopically for 6 h (early edema) or 8 days (late edema) after the first application of the CO and immediately after the animals were submitted to euthanasia for the collection of the samples (treated ears). For early edema, the tissue was biochemically evaluated for myeloperoxidase activity (MPO) and levels of nitrite/nitrate. In the late edema model, the ears were histologically evaluated for general morphometry, degranulated and non-degranulated mast cells, as well as acanthosis. RESULTS: Topic treatment with HCE-CS significantly reduced the early and late edema, as well as MPO activity and tissue levels of nitrite/nitrate. Finally, in the late edema model there was a lower density of degranulated mast cells in relation to the vehicle treated group and decreased thickness of the epidermis (acanthosis). CONCLUSION: These results suggest a possible benefit of topical treatment with HCE-CS in inflammatory conditions of the skin.

Role of the endocannabinoid system on the antihyperalgesic action of gabapentin in animal model of neuropathic pain induced by partial sciatic nerve ligation.

Gabapentin has antihyperalgesic action, decreasing central sensitization in neuropathic pain models; this effect depends on the mobilization of endogenous pain control pathways. This study aims to investigate the contribution of the endocannabinoid system to the antihyperalgesic action of gabapentin. Mus musculus Swiss, male, were submitted to PSL. On the 7th and 14th days post PSL, different groups were treated with CB1 receptor antagonist, AM281 via i.t. (2 µg/5 µl) or i.pl. (10 µg/20 µl) or CB2, AM630 via i.t. (5 µL i.t.) or (20 µL i.p.) and 15 min after gabapentin (30 mg / kg orally). Mechanical hyperalgesia was measured by the frequency of paw removal by the von Frey monofilament. Gabapentin demonstrated antihypernociceptive action, which was attenuated in animals pretreated with AM281 in both the i.t. and i.pl routes on the 7th and 14th days, differently from animals pretreated with AM630 that did not achieve a significant reduction with administration i.t. only on the 14th day with administration i.pl. The results show that endocannabinoid system contributes to the antihyperalgesic action of gabapetin in neuropathic pain by PSL, suggesting participation in the medullary and peripheral levels of CB1 receptors, and the peripheral performance of CB2 receptors.

Anti-hyperalgesic properties of ethanolic crude extract from the peels of Citrus reticulata (Rutaceae).

The therapeutic effects from Citrus reticulata on painful inflammatory ailments are associated to its flavonoids constituent and phytochemical studies with Citrus genus affirm that the peels have important amounts of it. These bioactive compounds have been a considerable therapeutic source and evaluate potential application of the peel extract is significant. This research aims to investigate the influence of ethanolic crude extract from the peels of Citrus reticulata and its possible mechanism of action in different animal models of pain. The extract reduced hyperalgesia in the second phase of formalin test (vehicle: 501.5 ± 40.0 s; C. reticulata extract 300 mg/kg: 161.8 ± 41.1 s), in the carrageenan model (vehicle at 4th h: 82.5 ± 9.6 %; C. reticulata extract 300 mg/kg at 4th h: 47.5 ± 6.5 %) and in Complete Freund's Adjuvant model (vehicle: 501.5 ± 40.0 s; C. reticulata extract 300 mg/kg: 161.8 ± 41.1 s). The possible contribution of opioidergic and adenosinergic systems in the anti-hyperalgesic effect of C. reticulata extract was observed after treatment, with non-selective antagonists for both systems, which produced reversal effects. In conclusion, these properties of C. reticulata extract suggest a potential therapeutic benefit in treating painful conditions.

Dextran Sulphate of Sodium-induced colitis in mice: antihyperalgesic effects of ethanolic extract of Citrus reticulata and potential damage to the central nervous system.

Citrus species are widely related to antihyperalgesic and anti-inflammatory effects. The aim of this study was to investigate if treatment with ethanolic extract from peels of mature Citrus reticulata Blanco causes antihyperalgesic effects on the referred mechanical hyperalgesia in a model of dextran sulphate of sodium (DSS)-induced colitis in mice, as well as the possible oxidative damage in different regions of the brain induced by its inflammatory reaction. Antihyperalgesia (30 to 300 mg/kg) was investigated by behavioral response (frequency of response to von Frey filament stimulation) in Swiss mice, while damage to central nervous system was investigated through techniques that evaluated oxidative stress using male black C57 BL6 mice (n=8). Treatment of the animals with the extract (100 mg/kg) from days 3 to 5 after colitis induction reduced referred the mechanical hyperalgesia (32.6 ± 5.1) in relation to the control group (57.4 ± 2.0). Levels of lipid peroxidation or carbonyl proteins were augmented in colitis-induced animals in relation to the disease group. These results indicated an antihyperalgesic effect of the studied extract and a potential impairment of the central nervous system functioning caused by inflammation during colitis, which could be related to mental disorders observed in patients suffering of this pathology.

Early fragmentation of polyester urethane sheet neither causes persistent oxidative stress nor alters the outcome of normal tissue healing in rat skin.

Silicone breast implant is associated with complications inherent to the surgical procedure. Prosthesis coating with polyurethane, however, commonly reduces the incidence of such complications. In this paper, the authors evaluated the inflammatory histomorphometric profile and oxidative damage associated to the implant of polyester urethane sheets. Forty-eight Wistar rats were divided into Sham or polyester urethane groups (n = 8/group) and underwent a polyester urethane implant in the dorsal skinfold. Tissue samples were collected on days seven, 30, and 90 after surgery and subjected to histomorphometric analysis and biochemical tests. Results were analyzed by one-way ANOVA (p ≤ 0.05). Peri-implant tissue samples exhibited characteristic inflammatory response associated with the biomaterial, with increased vascularization on day seven and augmented levels of IL1-b and TNF-a after 30 days. Peri-implant fibrocystic population was small on day seven, but increased considerably after 90 days. A rise in the carbonyl group levels of skin samples in the polyester urethane group was observed on day seven. Findings suggest that polyester urethane sheets undergo biodegradation at an early stage after implantation, followed by increased vascularity and microencapsulation of biomaterial fragments, without persistent oxidative damage. Fiber arrangement inside the collagen matrix results in a fibrotic scar because of polyester urethane degradation.

Hydroalcoholic crude extract of Casearia sylvestris Sw. reduces chronic post-ischemic pain by activation of pro-resolving pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Casearia sylvestris Sw. is widely used in popular medicine to treat conditions associated with pain. AIM OF THE STUDY: The present study investigated the influence of hydroalcoholic crude extract of Casearia sylvestris (HCE-CS) and contribution of pro-resolving mediators on mechanical hyperalgesia in a mouse model of chronic post-ischemia pain (CPIP). METHODS AND RESULTS: Male Swiss mice were subjected to ischemia of the right hind paw (3h), then reperfusion was allowed. At 10min, 24h or 48h post-ischemia/reperfusion (I/R), different groups of animals were treated with HCE-CS (30mg/Kg, orally [p.o]), selected agonists at the pro-resolving receptor ALX/FPR2 (natural molecules like resolvin D1 and lipoxin A4 or the synthetic compound BML-111; 0.1-1µg/animal) or vehicle (saline, 10mL/Kg, s.c.), in the absence or presence of the antagonist WRW4 (10µg, s.c.). Mechanical hyperalgesia (paw withdrawal to von Frey filament) was asseseed together with histological and immunostainning analyses. In these settings, pro-resolving mediators reduced mechanical hyperalgesia and HCE-CS or BML-111 displayed anti-hyperalgesic effects which was markedly attenuated in animals treated with WRW4. ALX/FPR2 expression was raised in skeletal muscle or neutrophils after treatment with HCE-CS or BML-111. CONCLUSION: These results reveal significant antihyperalgesic effect of HCE-CS on CPIP, mediated at least in part, by the pathway of resolution of inflammation centred on the axis modulated by ALX/FPR2.

Caffeine prevents antihyperalgesic effect of gabapentin in an animal model of CRPS-I: evidence for the involvement of spinal adenosine A1 receptor.

This study was designed to determine whether 3 weeks of gabapentin treatment is effective in alleviating neuropathic pain-like behavior in animal models of complex regional pain syndrome type-I and partial sciatic nerve ligation (PSNL). We investigated the contribution of adenosine subtypes to the antihyperalgesic effect of gabapentin by examining the effect of caffeine, a non-selective adenosine A1 and A2 receptor antagonist or 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), a selective adenosine A1 subtype receptor antagonist on this effect. Neuropathic pain was produced by unilateral prolonged hind paw ischemia and reperfusion (I/R) or PSNL procedures which resulted in stimulus-evoked mechanical hyperalgesia. After procedures, animals received gabapentin (10, 30, or 100 mg/kg intraperitoneal, respectively), caffeine (10 mg/kg intraperitoneal or 150 nmol intrathecally) or DPCPX (3 µg intrathecally) alone or in combination. Mice were tested for tactile mechanical hyperalgesia at 1, 2, and 3 weeks following procedures. Gabapentin produced dose-related inhibition of mechanical hyperalgesia over a 3-week period, and this effect was blocked by concomitant caffeine or DPCPX administration 1 week after injuries. The results of this study demonstrated that the mechanism through which gabapentin produces its effect may involve the activation of adenosine A1 subtype receptor.

Peripheral neurobiologic mechanisms of antiallodynic effect of warm water immersion therapy on persistent inflammatory pain.

Water immersion is widely used in physiotherapy and might relieve pain, probably by activating several distinct somatosensory modalities, including tactile, pressure, and thermal sensations. However, the endogenous mechanisms behind this effect remain poorly understood. This study examined whether warm water immersion therapy (WWIT) produces an antiallodynic effect in a model of localized inflammation and whether peripheral opioid, cannabinoid, and adenosine receptors are involved in this effect. Mice were injected with complete Freund's adjuvant (CFA; intraplantar; i.pl.). The withdrawal frequency to mechanical stimuli (von Frey test) was used to determine 1) the effect of WWIT against CFA-induced allodynia and 2) the effect of i.pl. preadministration of naloxone (a nonselective opioid receptor antagonist; 5 µg/paw), caffeine (a nonselective adenosine receptor antagonist; 150 nmol/paw), 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; a selective adenosine A1 receptor antagonist; 10 nmol/paw), and AM630 (a selective cannabinoid receptor type 2 antagonist; 4 µg/paw) on the antiallodynic effect of WWIT against CFA-induced allodynia. Moreover, the influence of WWIT on paw inflammatory edema was measured with a digital micrometer. WWIT produced a significant time-dependent reduction of paw inflammatory allodynia but did not influence paw edema induced by CFA. Naloxone, caffeine, DPCPX, and AM630 injected in the right, but not in the left, hind paw significantly reversed the antiallodynic effect of WWIT. This is the first study to demonstrate the involvement of peripheral receptors in the antiallodynic effect of WWIT in a murine model of persistent inflammatory pain.

Anti-inflammatory and antioxidant properties of hydroalcoholic crude extract from Casearia sylvestris Sw. (Salicaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Casearia sylvestris Sw. is widely used in popular medicine to treat inflammatory conditions. AIM OF THE STUDY: To investigate the anti-inflammatory and antioxidant properties of hydroalcoholic crude extract (HCE) taken from Casearia sylvestris Sw. (Salicaceae). METHODS AND RESULTS: The effect of the HCE from this plant (3-300 mg/kg) on the reduction of inflammatory response to carrageenan was investigated in pleurisy in rats (intrapleural, 2% in 0.2 mL) or paw edema in mice (intraplantar, 300 µg/20 µL, right hind paw). The plant anti-inflammatory action was assessed by its capability in inhibiting cell migration, enzymatic activity of myeloperoxidase (MPO) and production of nitrite/nitrate or edema. The in vitro antioxidant activity of this extract against lipid peroxidation and damage to proteins was assessed as possible pathways to contribute as anti-inflammatory mechanisms. Carrageenan-induced hind paw edema (739.3 ± 11.9 µm) was reduced by HCE (30 mg/kg: 462.8 ± 28.38 µm) to similar extents as dexametasone (365.1 ± 16.7). In pleurisy, treatment of the animals with HCE (100mg/kg: 0.010 ± 0.001 mU/mg of protein) also reduced MPO activity augmented by carrageenan (0.020 ± 0.001 mU/mg of protein) as well as leukocytes migration (carrageenan: 17.8890 ± 2.3900 leukocytes/mL, HCE 100mg/kg: 7.0880 ± 9631 leukocytes/mL). Significant effects were also observed in animals treated with different doses of HCE in biochemical tests for oxidative stress analysis. CONCLUSION: The anti-inflammatory and antioxidant effects of HCE from Casearia sylvestris Sw. suggests a potential therapeutic benefit of this plant in treatment of inflammatory conditions.

Endothelins contribute towards nociception induced by antigen in ovalbumin-sensitised mice.

1. The contribution of endogenous endothelins to nociceptive responses elicited by ovalbumin (OVA) in the hind-paw of mice sensitised to this antigen (50 microg OVA+5 mg Al(OH)(3), s.c., 14 days beforehand) was investigated. 2. Sensitised mice exhibited greater nocifensive responsiveness to intraplantar (i.pl.) OVA (total licking time over first 30 min: 85.2+/-14.6 s at 0.3 microg; 152.6+/-35.6 s at 1 microg) than nonsensitised animals (29.3+/-7.4 s at 1 microg). Nocifensive responses of sensitised mice to 0.3 microg OVA were inhibited by morphine (3 mg kg(-1), s.c.) or local depletion of mast cells (four daily i.pl. injections of compound 48/80). 3. Pretreatment with i.v. bosentan (mixed ET(A)/ET(B) receptor antagonist; 52 micromol kg(-1)) or A-122722.5 (selective ET(A) receptor antagonist; 6 micromol kg(-1)) reduced OVA-induced licking from 124.8+/-20.6 s to 45.7+/-13.0 s and 64.2+/-12.1 s, respectively, whereas A-192621.1 (selective ET(B) receptor antagonist; 25 micromol kg(-1)) enhanced them to 259.2+/-39.6 s. 4. Local i.pl. pretreatment with BQ-123 or BQ-788 (selective ET(A) or ET(B) receptor antagonists, respectively, each at 3 nmol) reduced OVA-induced licking (from 106.2+/-15.2 to 57.0+/-9.4 s and from 118.6+/-10.5 to 76.8+/-14.7 s, respectively). Sarafotoxin S6c (selective ETB receptor agonist, 30 pmol, i.pl., 30 min after OVA) induced nocifensive responses in OVA-sensitised, but not in nonsensitised, animals. 5. Compound 48/80 (0.3 microg, i.pl.) induced nocifensive responses per se and potentiated those induced by i.pl. capsaicin (0.1 microg). Treatment with BQ-123 (3 nmol, i.pl.) reduced only the hyperalgesic effect of compound 48/80, whereas BQ-788 (3 nmol) was ineffective. 6. Thus, immune-mediated Type I hypersensitivity reactions elicit mast cell- and endothelin-dependent nociception in the mouse hind-paw, which are mediated locally by both ET(A) and ET(B) receptors. The nocifensive response to antigen is amenable to blockade by systemic treatment with dual ET(A)/ET(B) or selective ET(A) receptor antagonists, but is sharply potentiated by systemic selective ET(B) receptor antagonist treatment. The apparently distinct roles played by ET(B) receptors in this phenomenon at local and other sites remain to be characterised.