Efeitos antinociceptivo e anti-inflamatório da lectina da alga marinha verde Caulerpa cupressoides no modelo de artrite induzida por zymosan na articulação temporomandibular de ratos

Abstract

Seaweeds are sources of bioactive compounds for the pharmaceutical industry and among these compounds include the lectins. The present study aimed to investigate the effects antinociceptive and anti-inflammatory of the lectin of the green seaweed Caulerpa cupressoides (CcL) on model of zymosan-induced arthritis in the temporomandibular joint (TMJ) of rats. CcL was extracted with 25 mM Tris-HCl buffer pH 7.5 and isolated by ion exchange chromatography on DEAE-cellulose column. In tests of arthritis induced by Zy, male Wistar rats received CcL (0.1, 1 or 10 mg/kg, i.v.) or sterile saline, 30 min before the intra-articular (i.art.) injection of Zy (2 mg/art.; 40 μL) into the left TMJ. Control groups received saline (40 μL; i.art.), indomethacin (5 mg/kg, s.c.) or morphine (5 mg/kg, s.c.). Groups of animals received CcL (10 mg/kg; i.v.) associated with mucin (8 mg/kg; i.v.), a sugar inhibitor, and another group received only mucin before stimulus. To analyze the involvement of HO-1 pathway in arthritis, animals were pretreated (3 mg/kg, s.c.) with a specific inhibitor of heme (zinc protoporphyrin IX-ZnPP IX). Finally, to evaluate the analgesic effect of CcL in the activation of the opioid system, group of animals received an injection i.art. (10 μg/art.; 15 µL) of the opioid receptor antagonist (naloxone), 35 min before injection of Zy. After 5 min, the animals were pretreated with CcL (10 mg/kg). Mechanical hypernociception was recorded before the i.art. injections of Zy or saline and after 4h. After 6 hour, the synovial fluid was collected to perform cell counting and myeloperoxidase (MPO) assay. Also, TMJ tissues were excised to perform histopathological, immunohistochemistry (TNF-α, IL-1β e HO-1) and cytokine assays (IL-1β) in the periarticular tissue and trigeminal ganglion. Pretreatment with CcL (0.1, 1 or 10 mg/kg; i.v.) inhibited (p<0.05) the nociceptive response (81, 83, and 89.5%, respectively) and reduced the influx of leukocytes (77.3, 80.7 and 98.5%, respectively) compared to Zy group, as demonstrated by MPO activity. Sugar inhibitor (mucin) did not inhibit the anti-inflammatory and antinociceptive effect of CcL in arthritis induced by Zy. We observed that during the histological analysis of ATM, animals treated with CcL showed a significant reduction of cell influx in the synovial membrane. Furthermore, CcL significantly reduced the production of IL-1β in the periarticular tissue and expression of IL-1β, TNF-α and HO-1 in the synovial membrane during immunohistochemistry assay. Treatment with ZnPP IX was not able to inhibit the effect CcL, indicating that its antinociceptive and anti-inflammatory action did not occur HO-1 pathway. In addition, treatment with naloxone did not reverse the effect of CcL. Therefore, CcL showed antinociceptive and anti-inflammatory effect on model of Zy-induced arthritis, reducing the production of primary cytokines (TNF-α and IL-1β), however its antinociceptive action did not occur by peripheral opioid mechanism.