水通道蛋白4在1,2-二氯乙烷中毒性脑水肿中表达研究

Expression of aquaporin 4 in 1,2-dichloroethane-induced toxic brain edema in rats

目的探讨水通道蛋白4(AQP4)在1,2-二氯乙烷(1,2-DCE)亚急性吸入所致中毒性脑水肿发生中的作用。方法无特定病原体级健康成年雌性SD大鼠,随机分为对照组(8只)、低剂量组(12只)和高剂量组(12只)。采用口鼻式动式吸入法染毒,3组大鼠1,2-DCE染毒剂量分别为0、600和1 800 mg/m3,连续7 d,8.0 h/d。染毒结束后,取大脑皮质行病理组织学检查,采用实时荧光定量聚合酶链反应法检测大脑皮质组织中基质金属蛋白酶2(MMP2)、钠-钾-氯共转运体1(NKCC1)、AQP4的mRNA相对表达水平,采用免疫印迹法检测大脑皮质组织中AQP4蛋白相对表达水平。结果病理组织学检查结果显示,低剂量组大鼠可见大脑皮质血管周围组织疏松,血管组织间隙扩大;高剂量组大鼠可见较明显的大脑皮质或血管周围组织疏松和空泡,程度较低剂量组严重。分别与对照组及低剂量组比较,高剂量组大鼠大脑皮质MMP2 mRNA相对表达水平均升高[(1.07±0.41)vs(1.56±0.55),(1.21±0.59)vs(1.56±0.55),P<0.05],AQP4 mRNA相对表达水平均下降[(1.03±0.25)vs(0.81±0.12),(1.00±0.20)vs(0.81±0.12),P<0.05];3组大鼠大脑皮质NKCC1 mRNA相对表达水平比较,差异无统计学意义[(1.03±0.31)vs(1.14±0.43)vs(1.36±0.50),P>0.05]。高剂量组大鼠大脑皮质AQP4蛋白相对表达水平低于对照组[(0.80±0.25)vs(1.19±0.42),P<0.05]。结论 1,2-DCE亚急性吸入所致大鼠脑水肿是以血管源性为主的混合型脑水肿,其发病机制与AQP4的表达量改变有关。

Objective To explore the effects of aquaporin 4（ APQ4） in rat toxic brain edema induced by subacute 1,2-dichloroethane（ 1,2-DCE） exposure. Methods Thirty-two specific pathogen free healthy adult female SD rats were randomly divided into control（ 8 rats）,low-dose（ 12 rats） and high-dose（ 12 rats） groups. The treatment groups were exposed to 1,2-DCE（ low-dose： 600 mg / m3; high-dose： 1 800 mg/m3,nose-only） and the control group was exposed to fresh air by dynamic inhalation for 8 hours per day for consecutive 7 days. After exposure,histopathologic changes were examined in the cerebral cortex. Real-time polymerase chain reaction was used to detect the mRNA relative expression of matrix metalloproteinase 2（ MMP2）,Na-K-Cl cotransporter-1（ NKCC1） and AQP4. The Western blotting was used to detect the expression of AQP4 protein in the cerebral cortex. Results The pathological results showed that the cerebral cortex tissues were loose around the peripheral vessels and the vessels tissue space appeared widen in low-dose exposure group. The pathological change was more serious in high-dose group than low-dose group,with obvious loosen vessels and vacuole. Compared with those of the control group and the low-dose group,the relative expression level of MMP2 mRNA in the high-dose group increased significantly[（ 1. 07 ± 0. 41） vs（ 1. 56 ± 0. 55）,（ 1. 21 ± 0. 59） vs（ 1. 56 ± 0. 55）,P〈0. 05],while the the relative expression level of AQP4 mRNA in the high-dose group significantly decreased [（ 1. 03 ±0. 25） vs（ 0. 81 ± 0. 12）,（ 1. 00 ± 0. 20） vs（ 0. 81 ± 0. 12）,P〈0. 05]. The relative expression levels of NKCC1 mRNA in all groups showed no statistical difference [（ 1. 03 ± 0. 31） vs（ 1. 14 ± 0. 43） vs（ 1. 36 ± 0. 50）,P〈0. 05]. The relative expression level of AQP4 protein in the high-dose group was lower than that of the control group [（ 0. 80 ± 0. 25） vs（ 1. 19 ± 0. 42）,P〈0. 05]. Conclusion The brain edema induced by subacute inhalation of 1,2-DCE is of mixed types with vasogenic edema as its main symptom. Its pathogenesis is related to the changes of AQP4 expression.