湿热应激和习服对小鼠气道黏液分泌的影响

目的：通过观察高温高湿环境暴露下小鼠气道黏液分泌相关蛋白在不同时间段的变化，探讨应激和习服在湿热环境中对呼吸系统疾病的作用。方法：45只BABL/c小鼠随机分成5组（n=9）：对照组、湿热1组、湿热2组、湿热3组、湿热4组。对照组普通环境饲养，7 d后处死。其余各组置入气候箱接受湿度（95±5）%，温度（33±0.5）℃的高温高湿刺激，第12小时处死为湿热1组，第24小时处死为湿热2组，第4天处死为湿热3组，第7天处死为湿热4组。免疫组化法检测小鼠肺黏蛋白5AC （MUC5AC）、表皮生长因子受体（EGFR）、水通道蛋白1（AQP1）、水通道蛋白5（AQP5）蛋白表达。结果：把小鼠置入高温高湿环境后，小鼠肺组织在12 h时AQP5增高，在24 h时MUC5AC、EGFR的蛋白表达增高，与正常组比较差异均有统计学意义（P<0.05）；第7天，MUC5AC蛋白表达水平显著低于正常组（P<0.05）；其余时间段，MUC5AC、EGFR、AQP5蛋白表达均与正常组无明显差异。AQP1蛋白表达在湿热各组均与正常组无差异，与湿热1组、湿热2组比较，湿热3组、湿热4组表达则减弱（P<0.05）。结论：湿热应激可引起小鼠气道黏液高分泌，持续处于该环境则可能产生一系列更复杂的反应。

Influence of hot-humid stress and acclimation on airway mucus production in lungs of mice

Objective:To study the change of airway mucus secretion under a high temperature and humidity environment, and explore the effects of hot-humid stress and acclimation on the morbidity and mortality of respiratory disease. Methods:Forty-five BABL/c mice were randomly divided into five groups:normal group, hot-humid group I, hot-humid group Ⅱ, hot-humid group Ⅲ, hot-humid group IV, with 9 mice in each group. Mice in normal group were continuously placed in the common environment and sacrificed after 7 days. Mice in other groups were housed in a temperature-and-humidity-controlled environment (33℃±0.5℃, 95%±5%). Mice in hot-humid group I, hot-humid group Ⅱ, hot-humid group Ⅲ and hot-humid group IV were sacrificed after 12 hours, 24 hours, 4 days, 7 days respectively. The protein expression of mucin 5AC(MUC5AC)、epidermal growth factor receptor (EGFR)、aquaporin 1(AQP1) and aquaporin 5(AQP5) in lung were tested by immunohistochemisty. Results:After housed in a high temperature and humidity environment, immunohistochemisty revealed a significant increase of AQP5 12 h later, MUC5AC and EGFR 24 h later, compared with normal group(P<0.05). There was a significant decrease of MUC5AC 7 d later, compared with normal group(P<0.05). There was no significant difference in MUC5AC, EGFR and AQP5 expression among all groups at other time points. There was no difference of AQP1 in humid heat groups, compared with normal group, but a significant decrease in humid heat Ⅲ and IV groups, compared with humid heat I and Ⅱ groups. Conclusion:These findings indicate that hot-humid stress induces mucus hypersecretion in airways, which may be related to the up-regulation of EGFR and down-regulation of AQP5 in MUC5AC. Although acclimation mitigates above-mentioned response, a series of more complex responses may be induced if still in the hot-humid environment.