The harmful effect of prolonged high-dose methylprednisolone in acute lung injury

Although many literatures have shown that prolonged high-dose administration of corticosteroids is hazardous and not indicated to therapy acute lung injury (ALI), there is little information on the harmful effect of prolonged high-dose corticosteroids in acute lung injury. In this study, we aimed to investigate the effect of prolonged high-dose methylprednisolone (MPL) on ALI and improve knowledge regarding the appropriate use of corticosteroids in ALL The different doses of MPL (3, 30, 180 mg.kg(-1)) were given via tail vein injection 1 h after the first time LPS administration and were daily administrated for 14 days. Lung tissues and lavage samples were isolated for biochemical determinations and histological measurements at 12 h, 7 days and 14 days after LPS administration. Single administration of 180 mg.kg(-1) MPL decreased the lung injury score, wet-to-dry ratio, the total cell numbers and level of procollagen type III in BALF at 12 h after LPS challenge. However, prolonged therapy with 180 mg.kg(-1) MPL for 7 days and 14 days decreased the number of AMs in BALF and increased the above-mentioned indexes. These results suggested that the prolonged high-dose MPL has harmful effects to treat LPS-induced ALI in rats. (C) 2012 Elsevier B.V. All rights reserved.