Avaliação do uso do antagonista dos receptores NMDA (MK- 801) como protetor no dano oxidativo em modelo experimental de lesão pulmonar aguda

• Autor(a) principal: Cunha, Aline Andrea da
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional PUCRS
• Texto Completo: http://hdl.handle.net/10923/1383
• topic: PULMÕES - DOENÇAS; BIOLOGIA MOLECULAR

Acute Lung Injury (ALI) is a syndrome of acute respiratory failure that results from pulmonary inflammation and acute pulmonary edema caused by the increased permeability of the alveolar-capillary barrier. In ALI, capillary endothelium and alveolar epithelium damage occurs resulting from the release of proinflammatory molecules, mainly cytokines, as a response to systemic insults. Free radical production is another important pathologic mechanism mediated by neurophils, which are capable of developing several clinical disorders found in ALI. It is well known that endogenous glutamate production stimulates the release of many inflammatory mediators, including aracdonic acid metabolites, free radicals and nitric oxide (NO). The first report describing a possible involvement of NMDA receptors in pulmonary physiophatology was based on a treatment with a selective inhibitor to this receptor (MK-801) used for the prevention of pulmonary edema caused by the increase of NMDA instilled intratracheally in rats under mechanic ventilation. The aim of this study was to evaluate the use of NMDA receptor antagonist (MK-801) as a protection against the oxidative injury in experimental model of ALI. Adult male Wistar rats were used. The animals were randomly divided into four groups: (1) intratracheal instillation (I. T. ) of 1 mL isotonic saline (n=6); (2) ALI induction with intratracheal LPS (100 \g/100 g of body weight) plus treatment with saline administered intraperitoneally (I. P. ) after ALI (n=6); (3) ALI induction plus MK- 801 (0. 3 mg/kg administered I. P. ) after ALI (n=6); and (4) ALI induction plus MK-801 (0. 3 mg/kg administered I. T. ) after ALI (n=6). Twelve hours after the treatment, the animals were anesthetized for blood collection using retroorbital puncture and bronchoalveolar lavage (BAL) was collected as well. After that, the animals were killed by decapitation and lung tissue was colleted. The treatment with MK-801 promoted a decrease in the total protein concentration, LDH activity and in the total cell number in BAL. In the lung tissue we verified a decrease of the oxidative injury measured by TBARS and NO levels and an improvement in antioxidant levels such as CAT, SOD, GSH and SH. We also verified an improvement in the inflammatory process as observed by the histopathology analysis of lung tissue. The results obtained in this study let us to conclude that treatment with MK-801 promoted an improvement in the inflammatory process and antioxidant levels, as well as a decrease of the oxidative injury in rats with intratracheal LPS-induced ALI.