Mechanism of melatonin alleviating lipopolysaccharide-induced damage to type Ⅱ alveolar epithelial cells of rats: relationship between melatonin receptors and mitochondrial fission proteins / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between melatonin receptors and mitochondrial fission proteins and to clarify the mechanism of melatonin alleviating lipopolysaccharide(LPS)-induced damage to type Ⅱ alveolar epithelial cells of rats.Methods:The rat type Ⅱalveolar epithelial cells were seeded in 6-well plates at a density of 2×10 5 cells/ml and divided into 5 groups ( n=10 each) using a random number table method: control group (C group), LPS group (L group), LPS plus melatonin group (LM group), LPS plus melatonin receptor blocking group (LL group), and LPS plus melatonin plus melatonin receptor blocker group (LML group). The model of LPS-induced damage to cells was established by incubating with LPS 10 μg/ml for 24 h. Melatonin 0.1 mmol/L and/or melatonin receptor blocker luzindole 0.2 μmol/L was added in LM group, LL group and LML group.The concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay after the end of incubation.The mitochondrial respiratory control rate (RCR) was measured by GENMED purified mitochondrial RCR quantitative detection kit in each group.Western blot was used to detect the expression of dynamin-related protein 1 (Drp1) and mitochondrial adaptor fission 1 (Fis1). Results:Compared with C group, the concentrations of TNF-α and IL-6 in culture medium were significantly increased, RCR was decreased, and the expression of Drp1 and Fis1 was up-regulated in L, LM, LL and LML groups ( P<0.05). Compared with L group, the concentrations of TNF-α and IL-6 in culture medium were significantly decreased, RCR was increased, and the expression of Drp1 and Fis1 was down-regulated in LM group ( P<0.05), and no significant change was found in parameters mentioned above in LL group ( P>0.05). Compared with LM group, the concentrations of TNF-α and IL-6 in culture medium were significantly increased, RCR was decreased, and the expression of Drp1 and Fis1 was up-regulated in LML group ( P<0.05). Conclusion:The mechanism by which melatonin attenuates LPS-induced damage to type Ⅱ alveolar epithelial cells is related to activating melatonin receptors and inhibiting the expression of mitochondrial fission proteins in rats.