缺氧缺血新生大鼠脑组织水通道蛋白4的表达变化

Changes of aquaporin.4 expression in brain tissue of hypoxic-ischemic neonatal rats

目的研究缺氧缺血性脑损伤（HIBD）病理过程中水通道蛋白4（aquaporin-4，AQP-4）的作用及其意义。方法120只7日龄新生Wistar大鼠按照完全随机化方法分为4部分，每部分（n=30）再分为对照组、HIBD后6h、24h、3d、5d和7d共6组，每组5只。分别测定脑组织含水量；原位杂交和免疫组化检测AQP-4表达；检测脑组织病理变化。结果HIBD组6h、24h、3d的脑组织含水量较对照组显著增加（P〈0．05）；且各组脑组织含水量随时间延长而增加，组间差异有统计学意义（P〈0．05）；HIBD5d、7d组脑组织含水量与对照组比较差异无统计学意义（P〉0．05）。对照组AQP-4mRNA和AQP-4蛋白少量表达（吸光度A值为0．29±0．07和0．06±0．01）。与对照组相比，HIBD后6～24h，AQP-4mRNA和AQP．4蛋白表达显著增加。AQP-4mRNA的A值由0．42±0．04上升到0．80±0．02（P〈0．05）；AQP．4蛋白A值由0．14±0．03上升到0．23±0．05（P〈0．05），同时光镜下可见脑组织轻度水肿；3d时AQP．4mRNA和蛋白表达达高峰，AQP．4mRNA的A值为0．91±0．08，AQP-4蛋白A值为0．41±0．04，此时脑组织严重水肿，神经元、胶质细胞和内皮细胞明显肿胀；第5～7天AQP-4的表达已下降（尤其mRNA明显），但仍显著高于对照组（P〈0．05），此时脑水肿已减轻。在整个HIBD脑水肿形成的过程中，AQP-4mRNA和蛋白的表达呈正相关（rs〉0．82，只〈0．05）。结论AQP-4参与了HIBD的发生发展过程，AQP-4在HIBD脑水肿的形成过程中可能起重要作用。

Objective To study the relationship between the expression of aquaporin-4（AQP-4）and hypoxic-ischemic brain damage（HIBD） in neonatal rats. Metheods Totally 120 seven-day-old Wistar rats were assigned to four parts, each part （n = 30） was divided into six groups, including control group, HIBD 6 h, 24 h,3 d,5 d,7 d（n =5 per group ）. The model of HIBD was induced by unilateral carotid ligation followed by exposure to 8% oxygen. In situ hybridization and immunohistochemistry were respectively used to evaluate AQP-4 mRNA and protein expression, and the light microscopic changes were observed by HE staining. Results The brain water content was increased markedly in HIBD group after 6 h,24 h,3 d of HIBD and increased further with time in neonatal rats compared with that in the control group. The expression levels of AQP-4 mRNA and protein were low in the control group. Compared with the control group, there showed significant increase in AQP-4 mRNA and protein expression on the cerebral tissue at the 6th and 24th hour in rats following HIBD. AQP-4 mRNA expression（A Value） increased from 0.42 ± 0.04 to 0.80 ± 0. 02 （ P 〈 0. 05） and AQP- 4 protein expression （A） increased from 0. 14 ± 0.03 to 0.23 ±0.05. Histological study showed that the cerebral tissue had a light swelling. At day 3, the expression levels of AQP-4 mRNA and protein reached at its maximum. AQP-4 mRNA expression（A） reached at 0.91 ±0.08 and AQP-4 protein expression（A） at 0.41 ± 0.04 （P 〈 0.05 ）. The brain edema became remarkable, neurons and glias together with endothelial cells were all remarkably swelling. At day 5 and 7, the expression levels of AQP-4 mRNA and protein in HIBD group were still higher than those in the control group（ P 〈 0.05 ） ,and the brain edema were not remarkable. The AQP-4 mRNA expression showed a positive correlation with the AQP-4 protein expression during the HIBD formation （ rs 〉 0. 82, Ps 〈 0.05 ）. Conclusions The increased expression of AQP- 4 participates in the development of cerebral edema after HIBD. AQP-4 may play an important role in the pathological development of HIBD.