P38、MAPK-1和AQP-4在糖皮质激素调节大鼠创伤性脑水肿中的作用

目的 探讨糖皮质激素对P38、丝裂原活化蛋白激酶（MAPK-1）的调节作用及其对大鼠创伤后脑组织水通道蛋白 4（AQP-4）表达的影响。方法 选择SPF级雄性SD大鼠140只，随机分为假手术组、模型组、低剂量治疗和高剂量治疗组，各35只。假手术组单纯实施开颅手术，模型组、低剂量治疗组和高剂量治疗组用Feeney's自由落体法制备大鼠脑创伤模型，高剂量治疗组和低剂量治疗组分别予高、低甲泼尼龙尾静脉注射。分别于伤后0、6、24、72 h、7 d处死动物，取脑组织标本，透射电镜观察各组大鼠神经细胞结构变化，免疫组化法测定各组大鼠AQP-4、P38、MAPK-1的表达水平，用荧光探针原位杂交法测定AQP-4mRNA的表达。结果 ①假手术组大鼠脑神经结构基本正常，细胞质、细胞膜及细胞核完整清晰。模型组神经细胞体积缩小，细胞膜结构破坏，胞浆疏松，细胞核固缩，凋亡小体形成。与模型组相比，低剂量治疗组、高剂量治疗组大鼠神经细胞坏死程度均较轻。②低剂量治疗组及高剂量治疗组大鼠伤后24、72 h及7 d的AQP-4阳性表达率均低于模型组，差异有统计学意义（P＜0.05），低剂量与高剂量治疗组间表达比较，差异无统计学意义（P＞0.05）。低剂量治疗组及高剂量治疗组大鼠在伤后24、72 h及7 d的P38、MAPK-1阳性表达率均低于模型组，差异有统计学意义（P＜0.05），低剂量与高剂量治疗组间比较，差异无统计学意义（P＞0.05）。③低剂量治疗组和高剂量治疗组的AQP-4mRNA阳性表达率在伤后24、72 h及7 d均低于模型组，高于假手术组，差异有统计学意义（P＜0.05）；低剂量与高剂量治疗组间比较，差异无统计学意义（P＞0.05）。结论 糖皮质激素可以降低大鼠创伤后脑组织AQP-4 的表达及脑损伤，其作用机制可能与抑制P38、MAKP-1激活、降低下游 AQP-4 的表达有关。

The Role of P38,MAPK-1 and AQP-4 in Glucocorticoid Regulation of Traumatic Brain Edema in Rats

Objective To investigate the effects of glucocorticoids on P38 and mitogen-activated protein kinase (MAPK-1) and their effects on the expression of aquaporin-4 (AQP-4) in rat brain after trauma. Methods A total of 140 SPF male Sprague-Dawley rats were randomly divided into sham operation group, model group, low-dose treatment and high-dose treatment group, 35 each. The sham operation group was only performed with craniotomy. The model group, the low-dose treatment group and the high-dose treatment group were prepared by Feeney's free fall method. The high-dose treatment group and the low-dose treatment group were given high and low methylprednisolone. Injection into the tail vein. The animals were sacrificed at 0, 6, 24, 72 h and 7 d after injury, and brain tissue samples were taken.The changes of nerve cell structure in each group were observed by transmission electron microscopy. The expression levels of AQP-4, P38 and MAPK-1 in each group were determined by immunohistochemistry. The expression of AQP4 mRNA was determined by fluorescence probe in situ hybridization. Results ①In the sham operation group, the brain structure of the brain was basically normal, and the cytoplasm, cell membrane and nucleus were intact. In the model group, the volume of nerve cells was reduced, the cell membrane structure was destroyed, the cytoplasm was loose, the nucleus was pyknosis, and apoptotic bodies were formed. Compared with the model group, the degree of neuronal necrosis was lower in the low-dose treatment group and the high-dose treatment group. ②The positive expression rate of AQP-4 in the low-dose treatment group and the high-dose treatment group was lower than that in the model group at 24, 72 h and 7 d after injury,the difference was statistically significant (P<0.05). There was no significant difference in the expression between the low-dose and high-dose groups (P>0.05). The positive expression rates of P38 and MAPK-1 in the low-dose treatment group and the high-dose treatment group were lower than those in the model group at 24, 72 h and 7 d after injury,the difference was statistically significant (P<0.05). There was no significant difference between the low-dose and high-dose groups (P>0.05). ③The positive expression rate of AQP4 mRNA in low-dose treatment group and high-dose treatment group was lower than that in model group at 24, 72 h and 7 d after injury, which was significantly higher than that in sham operation group (P<0.05).There was no significant difference between the low-dose and high-dose groups (P>0.05). Conclusion Glucocorticoid can decrease the expression of AQP-4 and brain damage in rat brain after trauma, and its mechanism may be related to inhibition of P38, MAKP-1 activation and reduction of downstream AQP-4 expression.