Mirna Marques Bezerra

Low-dose doxycycline prevents inflammatory bone resorption in rats

Matrix metalloproteinases (MMP) are considered to be key initiators of collagen degradation, thus contributing to bone resorption in inflammatory diseases. We determined whether subantimicrobial doses of doxycycline (DX) (< or =10 mg kg-1 day-1), a known MMP inhibitor, could inhibit bone resorption in an experimental periodontitis model. Thirty male Wistar rats (180-200 g) were subjected to placement of a nylon thread ligature around the maxillary molars and sacrificed after 7 days. Alveolar bone loss (ABL) was measured macroscopically in one hemiarcade and the contralateral hemiarcade was processed for histopathologic analysis. Groups of six animals each were treated with DX (2.5, 5 or 10 mg kg-1 day-1, sc, 7 days) and compared to nontreated (NT) rats. NT rats displayed significant ABL, severe mononuclear cell influx and increase in osteoclast numbers, which were significantly reduced by 5 or 10 mg kg-1 day-1 DX. These data show that DX inhibits inflammatory bone resorption in a manner that is independent of its antimicrobial properties.

Antinociceptive and anti-inflammatory activities of a sulfated polysaccharide isolated from the green seaweed Caulerpa cupressoides

BACKGROUND Red and brown algae sulfated polysaccharides (SPs) have been widely investigated as antinociceptive and/or anti-inflammatory agents; however, no description of these biological properties concerning green algae SPs have been reported. Caulerpa curpressoides (Chlorophyta) presents three SPs fractions (Cc-SP1, Cc-SP2, and Cc-SP3). Anticoagulant (in vitro) and anti- and pro-thrombotic (in vivo) effects of Cc-SP2 had been recently reported. We evaluated the effects of Cc-SP2 using models of nociception and acute inflammation in vivo. METHODS Male Swiss mice received Cc-SP2 (iv) 30 min prior to receiving 0.6% acetic acid (10 ml/kg, ip), 1% formalin (20 μl, sc) or were subjected to thermal stimuli (51 ± 1 °C). Cc-SP2 was injected sc to male Wistar rats in a peritonitis model or a paw edema model using carrageenan (ip or ipl, 500 μg). To analyze the systemic effects, Cc-SP2 (27 mg/kg, sc) was administrated to both genders mice before waiting for 14 days. RESULTS Cc-SP2 (3, 9 or 27 mg/kg) reduced (p < 0.05) the number of writhes induced by acetic acid by 57, 89.9 and 90.6%, respectively, the licking time in the first (9 or 27 mg/kg with 42.47 and 52.1%, respectively) and the second (3, 9 or 27 mg/kg with 68.95, 82.34 and 84.61%, respectively) phases. In the hot-plate test, the antinociceptive effect of Cc-SP2 (9 mg/kg) was primarily observed at 60 min (26.7 ± 1.2 s), with its effect reversed by naloxone (8.6 ± 1.3 s), suggesting the involvement of the opioid system. Cc-SP2 (3, 9 or 27 mg/kg, sc, p < 0.05) showed anti-inflammatory effects by decreasing neutrophils migration by 64, 69 and 73%, respectively, and potently reduced the paw edema, especially at the second (0.16 ± 0.02, 0.16 ± 0.03 and 0.12 ± 0.05 ml) and third (0.16 ± 0.03, 0.18 ± 0.02 and 0.14 ± 0.04 ml) hours, respectively. Cc-SP2 did not cause hepatic or renal alterations or affect body mass or the macroscopy of the organs examined (p > 0.05). Histopathological analyses of the liver and kidney showed that both organs were affected by Cc-SP2 treatment, but these effects were considered reversible. CONCLUSION The results indicate that the analgesic and anti-inflammatory effects of Cc-SP2 could be of biomedical applicability as a new, natural tool in pain and acute inflammatory conditions.

Reactive nitrogen species scavenging, rather than nitric oxide inhibition, protects from articular cartilage damage in rat zymosan‐induced arthritis

The contribution of nitric oxide (NO) and peroxynitrite (PN) to inflammation in a zymosan‐induced (1 mg, intra‐articular, i.art.) rat model of arthritis was assessed by histopathology and by measuring the glycosaminoglycan (GAG) content of the articular cartilage. Progression of the chronic synovitis in zymosan‐induced arthritis (ZYA) was associated with increased nitrite and nitrotyrosine (3‐NT) levels in the joint exudates that paralleled a progressive loss of the GAG content. An increase in 3‐NT was also observed after i.art. PN. The nonselective nitric oxide synthase (NOS) inhibitor L‐NG‐nitroarginine methyl ester (25–75 mg kg−1day−1) or the selective inducible NOS inhibitor aminoguanidine (50–100 mg kg−1day−1) given 1 h before (prophylactic) or 3 days after (therapeutic) injection of the zymosan ameliorated the synovitis, but worsened the GAG loss, as measured at the end of the experiment (day 7). The PN scavenger uric acid (100–250 mg kg−1 i.p. four times daily) given prophylactically until the end of the experiment (day 14), in a dose compatible with its PN scavenging activity, significantly decreased both the synovitis and the GAG loss. In conclusion, PN formation is associated with cartilage damage in addition to proinflammatory activity in ZYA. NOS inhibitors and a PN scavenger were able to reduce the cellular infiltration, while displaying opposite effects on cartilage homeostasis either by enhancing or ameliorating the damage, respectively.

Antinociceptive and Anti-Inflammatory Activities of Sulphated Polysaccharides from the Red Seaweed Gracilaria cornea

Seaweeds have attracted special interest as good sources of sulphated polysaccharides (SP) for use in pharmaceutical industries and biotechnology. In this study, we evaluated the effects of SP from the red seaweed Gracilaria cornea (Gc-TSP) in nociceptive and inflammatory models. In mice, Gc-TSP (3, 9 or 27 mg/kg) significantly reduced nociceptive responses, as measured by the number of writhes, at all tested doses. In a formalin test, Gc-TSP significantly reduced licking time in both phases of the test at a dose of 27 mg/kg. In a hot-plate test, the antinociceptive effect was observed only in animals treated with 27 mg/kg of Gc-TSP, suggesting that the analgesic effect occurs through a central action mechanism at the highest dose. Gc-TSP (3, 9 or 27 mg/kg) caused only a slight reduction in neutrophil migration in the rat peritoneal cavity. However, lower doses of Gc-TSP (3 and 9 mg/kg) significantly inhibited paw oedema induced by carrageenan, especially at 3 hr after treatment. Reduction in oedema was confirmed by myeloperoxidase activity in the affected paw tissue. In addition, treatment (s.c.) of animals with different doses of Gc-TSP inhibited paw oedema induced by dextran within the first hour in all doses tested. After 14 consecutive days of intraperitoneal administration of Gc-TSP (9 mg/kg), we measured the wet weight of the liver, kidney, heart, spleen and thymus and performed biochemical, haematological and histopathological evaluations. No systemic damage was found. These results indicate that Gc-TSP possesses analgesic and anti-inflammatory effects and is a potentially important tool worthy of further study.

Experimental Model of Zymosan-Induced Arthritis in the Rat Temporomandibular Joint: Role of Nitric Oxide and Neutrophils

Aims. To establish a new model of zymosan-induced temporomandibular joint (TMJ) arthritis in the rat and to investigate the role of nitric oxide. Methods. Inflammation was induced by an intra-articular injection of zymosan into the left TMJ. Mechanical hypernociception, cell influx, vascular permeability, myeloperoxidase activity, nitrite levels, and histological changes were measured in TMJ lavages or tissues at selected time points. These parameters were also evaluated after treatment with the nitric oxide synthase (NOS) inhibitors L-NAME or 1400 W. Results. Zymosan-induced TMJ arthritis caused a time-dependent leucocyte migration, plasma extravasation, mechanical hypernociception, and neutrophil accumulation between 4 and 24 h. TMJ immunohistochemical analyses showed increased inducible NOS expression. Treatment with L-NAME or 1400 W inhibited these parameters. Conclusion. Zymosan-induced TMJ arthritis is a reproducible model that may be used to assess both the mechanisms underlying TMJ inflammation and the potential tools for therapies. Nitric oxide may participate in the inflammatory temporomandibular dysfunction mechanisms.

Nitric oxide and cyclooxygenase may participate in the analgesic and anti-inflammatory effect of the cucurbitacins fraction from Wilbrandia ebracteata.

Wilbrandia ebracteata is a medicinal plant from South America used in folk medicine for the treatment of chronic rheumatic diseases. We have shown that the high performance liquid chromatography-characterized (HPLC) dichloromethane fraction isolated from Wilbrandia ebracteata (WEDC) inhibits the parameters observed in experimental models of inflammation in vivo and in vitro. In the present study, we extend our previous observations on the analgesic effects of WEDC by investigating its actions using the hot plate test and zymosan-induced writhing test in mice, as well as zymosan-induced arthritis in rats evaluating articular inflammatory pain, cell migration and determination of NO release into the joint exudate. The effect of WEDC on the activity of COX-1 and COX-2 in vitro and its ulcerogenic capacity in vivo were also investigated. The oral treatment of the animals with WEDC (1-10 mg/kg) produced a significant, dose-dependent reduction of articular incapacitation and abdominal contortions in the writhing test. The same effect was not observed in the hot plate and rota-rod tests. WEDC also reduced nitrite release into the zymosan-inflamed joints. In the evaluation of COX activity, we observed that WEDC was able to selectively inhibit COX-2 but not COX-1 activity in COS-7 cells. Moreover, WEDC treatment did not show gastrointestinal toxicity. Our data confirm the anti-nociceptive activities of the WEDC and indicate that this effect could be associated with inhibition of cyclooxygenase-2 (COX-2) and nitric oxide release. The effects could be attributed to cucurbitacins since several of these were isolated from the WEDC.

Heme oxygenase/carbon monoxide-biliverdin pathway may be involved in the antinociceptive activity of etoricoxib, a selective COX-2 inhibitor

The aim of this study was to assess the interaction between the heme oxygenase-1/ biliverdin/carbon monoxide (HO-1/BVD/CO) and cyclooxygenase-2 (COX-2) pathways in the writhing test. Mice were pretreated with 0.1, 1 or 10 mg/kg, ip etoricoxib, a selective COX-2 inhibitor, or with one of the following HO-1/BVD/CO pathway modulators: 1, 3 or 9 mg/kg, sc ZnPP IX, a specific HO-1 inhibitor, 0.3, 1 or 3 mg/kg, sc hemin, a substrate of the HO-1/BVD/CO pathway; or 0.00025, 0.025 or 2.5 μmol/kg, sc DMDC, a CO donor. Mice pretreated with etoricoxib or one of the HO-1/BVD/CO pathway modulators received an injection of acetic acid (ip) after 30 and 60 min, respectively. Next, the number of writhes was quantified between 0 and 30 min after stimulus injection. In another series of experiments, ineffective doses of etoricoxib were co-administered with hemin or DMDC and an effective dose of etoricoxib with ZnPP IX, followed by an acetic acid injection. Four hours after the acetic acid injection, levels of bilirubin, which is a product of BVD conversion by the BVD reductase enzyme, in the peritoneal lavage were determined. Hemin or DMDC reduced (p<0.05) the number of writhes, but ZnPP IX potentiated (p<0.05) the effect of acetic acid by increasing (p < 0.05) the number of writhes. The co-administration of etoricoxib with hemin or DMDC reduced (p<0.05) the number of writhes. However, the analgesic effect of etoricoxib was not observed in the presence of ZnPP IX. Pretreatment with ZnPP IX reduced bilirubin levels, but etoricoxib pretreatment significantly increased the bilirubin concentration in peritoneal exudates. The data obtained from these experiments showed that the HO-1/BVD/CO pathway was activated in the acetic acid-induced abdominal writhing model. The analgesic effect of etoricoxib was at least partially dependent on the participation of the HO-1/BVD/CO pathway.

Efficacy and safety of combined piroxicam, dexamethasone, orphenadrine, and cyanocobalamin treatment in mandibular molar surgery

Third molar extraction is a common procedure frequently accompanied by moderate or severe pain, and involves sufficient numbers of patients to make studies relatively easy to perform. The aim of the present study was to determine the efficacy and safety of the therapeutic combination of 10 mg piroxicam, 1 mg dexamethasone, 35 mg orphenadrine citrate, and 2.5 mg cyanocobalamin (Rheumazin) when compared with 20 mg piroxicam alone (Feldene) in mandibular third molar surgery. Eighty patients scheduled for removal of the third molar were included in this randomized and double-blind study. They received (vo) Rheumazin or Feldene 30 min after tooth extraction and once daily for 4 consecutive days. Pain was determined by a visual analogue scale and by the need for escape analgesia (paracetamol). Facial swelling was evaluated with a measuring tape and adverse effects and patient satisfaction were recorded. There was no statistically significant difference in facial swelling between Rheumazin and Feldene (control group). Both drugs were equally effective in the control of pain, with Rheumazin displaying less adverse effects than Feldene. Therefore, Rheumazin appears to provide a better risk/benefit ratio in the mandibular molar surgery. Since the side effects resulting from nonsteroidal anti-inflammatory drug administration are a severe limitation to the routine use of these drugs in clinical practice, our results suggest that Rheumazin can be a good choice for third molar removal treatment.

A lectin from the green seaweed Caulerpa cupressoides reduces mechanical hyper-nociception and inflammation in the rat temporomandibular joint during zymosan-induced arthritis

Seaweed lectins have been widely investigated as anti-nociceptive and anti-inflammatory agents. This study analyzed the anti-nociceptive and anti-inflammatory responses of a lectin from the green seaweed Caulerpa cupressoides (CcL) on zymosan-induced arthritis of the rat temporomandibular joint (TMJ). Rats received i.v. CcL 30 min prior to injection of zymosan (2mg/art.) or 0.9% saline into the left TMJ. Mechanical hyper-nociception was measured by the electronic von Frey method at baseline and 4h after zymosan injection. Animals were euthanized 6h after zymosan injection and the synovial fluid was collected for leukocyte counting and myeloperoxidase activity assessment. Other animals were treated with ZnPP-IX (3mg/kg; s.c.), a specific heme oxygenase-1 pathway inhibitor, and naloxone (10 μg/art.), a nonselective opioid receptor antagonist. TMJ tissues were excised to perform histopathological and immunohistochemistry analyses. CcL (0.1, 1 or 10mg/kg) significantly reduced zymosan-induced hyper-nociception (81, 83 and 89.5%, respectively) and inhibited the leukocyte influx (77.3, 80.7 and 98.5%, respectively) compared with the zymosan-only group, as confirmed by myeloperoxidase activity; however, treatment with naloxone or ZnPP-IX did not revert the effects of CcL (10mg/kg), suggesting that the naloxone-sensitive opioid and heme oxygenase-1 pathways are not involved. CcL also reduced the leukocyte influx and the expression of IL-1β and TNF-α in the TMJ, based on histopathological and immunohistochemistry analyses, respectively. Therefore, CcL reduces TMJ hyper-nociception and inflammation with a mechanism that is partially dependent on TNF-α and IL-1β inhibition. CcL reveals a potentially valuable alternative tool for future studies of TMJ disorders.

Tephrosia toxicaria Pers. reduces temporomandibular joint inflammatory hypernociception: The involvement of the HO‐1 pathway

We investigated both the efficacy and the sub‐chronic toxicity of Tephrosia toxicaria Pers. in the zymosan‐induced temporomandibular joint (TMJ) inflammatory hypernociception in rats evaluating the possible role of heme oxygenase‐1 (HO‐1).