Effect of agmatine on apoptosis of type Ⅱ alveolar epithelial cells in rats with hyperoxia-induced acute lung injury / 中国中西医结合急救杂志

ABSTRACT

Objective To investigate the effects of agmatine (AGM) on the apoptosis of type Ⅱ alveolar epithelial cells (AECⅡ) in rats with hyperoxia-induced acute lung injury (HALI) and provide a theoretical basis for the treatment of HALI. Methods A total of 24 Sprague-Dawley (SD) rats were randomly divided into three groupsnormal control group (fed in air), HALI model group and AGM pretreatment group (400 mg/kg AGM was given before the hyperoxia treatment or HALI model establishment), each group with 8 rats. The rats were placed in a self-made high oxygen model box with oxygen concentration of > 90%, temperature of 25-27 ℃, humidity of 50%-70% and carbon dioxide concentration < 0.5% to replicate the HALI rat model; no any treatment was given to the normal control group. After the hyperoxia was treated for 48 hours, the arterial blood was taken from the rat carotid artery for blood gas analysis;under light microscope, the pathological changes of lung tissues were observed and the pathological evaluation scores were carried out; the contents of tumor necrosis factor-α (TNF-α) and interleukins (IL-6, IL-1) in bronchoalveolar lavage fluid (BALF) were detected by enzyme-linked immunosorbent assay (ELISA); the apoptosis of AECⅡ of lung tissues was determined by flow cytometry, and the apoptotic rate was calculated; the expressions of the apoptosis related protein Bcl-2 and Bax were detected by Western Blot. Results Compared with the normal control group, the oxygenation index (OI) and Bcl-2 of HALI model group and AGM pretreatment group were significantly decreased [OI (mmHg, 1mmHg = 0.133 kPa) 135.04±16.82 vs. 463.74±22.04, Bcl-2 protein expression (A value) 0.35±0.18 vs. 0.89±0.08], while the respiratory index (RI), pathological scores of lung injury, TNF-α, IL-6, IL-1, the apoptosis rate of AECⅡ, Bax protein expression were all significantly increased [RI 1.29±0.15 vs. 0.24±0.03, pathological score of lung tissue 4.72±1.32 vs. 0, TNF-α (μg/L) 44.48±1.42 vs. 14.12±0.88, IL-6 (μg/L) 51.46±1.62 vs. 23.20±0.89, IL-1 (μg/L) 44.03±2.45 vs. 11.64±1.34, apoptosis rate of AECⅡ (56.24±1.14)% vs. (22.64±0.58)%, Bax protein expression (A value) 2.37±0.34 vs. 1.41±0.48, all P < 0.05]. Compared with HALI model group, the OI and Bcl-2 of AGM pretreatment group were significantly increased [OI (mmHg) 364.72±14.56 vs. 135.04±16.82, Bcl-2 protein expression (A value) 0.68±0.10 vs. 0.35±0.18, all P < 0.05], while the RI, pathological scores of lung injury, TNF-α, IL-6, IL-1, apoptosis rate of AECⅡ, and Bax protein expression were significantly decreased [RI 0.45±0.09 vs. 1.29±0.15, pathological score of lung tissue 2.30±0.96 vs. 4.72±1.32, TNF-α (μg/L)22.98±0.72 vs. 44.48±1.42, IL-6 (μg/L) 35.79±0.86 vs. 51.46±1.62, IL-1 (μg/L) 24.06±0.86 vs. 44.03±2.45, apoptosis rate of AECⅡ (28.58±1.21)% vs. (56.24±1.14)%, Bax protein expression (A value) 1.98±0.42 vs. 2.37±0.34, all P < 0.05]. Conclusion The apoptotic rate of AECⅡ in HALI rats is reduced by AGM, and the regulatory mechanism needs to be further studied.