Xiong Li, Zhang Jun-Jian, Sun Dong, Liu Hui, Zhang Lei
Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
Zhonghua Yi Xue Za Zhi. 2009 Apr 21;89(15):1071-4.
To investigate the Influence of chronic cerebral hypoperfusion on gap junction ultrastructure and expression of connexin (Cx)36, Cx32, and Cx26 in hippocampus the microstructure of gap junction and the expression of gap junction subunits in the hippocampus of cognition impaired animals. Cognition impairment was induced by the permanent occlusion of the carotid arteries (2-VO).
Twenty-seven Wistar rats underwent two-vessel occlusion (2-VO, ligation of bilateral common carotid arteries) and then were randomly divided into 2 equal groups: 2-VO 3 week, 2-VO 8 week and 2-VO 12 week groups to undergo Morris water maze test 3, 8, and 12 weeks later to observe the spatial learning and memory ability. Another 9 rats underwent sham operation to be used as control group. After Morris water maze test the rats were killed. The brains were taken out from 3 rats from each group to undergo thin-section transmission electron microscopy to observe the ultrastructure of the gap junctions in the CA1 area of hippocampus. RT-PCR and Western blotting were used to detect the mRNA and protein expression of Cx 36, Cx32, and Cx26 in the hippocampus of the other 27 rats, 6 from each group.
Compared to the control group, the density of cytomembrane of gap junction was lower, the interspace of gap junction were larger in the 2-VO 3 week group, and these abnormalities were gradually improved in the 2-VO 8 and 12 week groups. The mRNA and protein levels of Cx36 and Cx32 of the three 2-VO groups were the lowest in the 2-VO 3 week group, and then gradually increased, however, all significantly lower than those of the control group (all P < 0.05). The mRNA level of Cx26 was not altered significantly, while the protein expression levels of Cx26 in the three 2-VO groups were all higher compared with the control group (all P < 0.05).
The altered neuronal gap junction may participate in the cognition impairment caused by chronic cerebral hypoperfusion.
研究慢性脑灌注不足对认知功能受损动物海马中缝隙连接超微结构及连接蛋白（Cx）36、Cx32和Cx26表达的影响，以及缝隙连接的微观结构和缝隙连接亚基在海马中的表达。通过永久性结扎颈动脉（2-VO）诱导认知功能障碍。
27只Wistar大鼠接受双血管闭塞（2-VO，双侧颈总动脉结扎），然后随机分为2组，每组9只：2-VO 3周组、2-VO 8周组和2-VO 12周组，分别在3、8和12周后进行Morris水迷宫试验，观察空间学习和记忆能力。另9只大鼠接受假手术作为对照组。Morris水迷宫试验后处死大鼠。每组取3只大鼠的脑进行超薄切片透射电子显微镜检查，观察海马CA1区缝隙连接的超微结构。采用RT-PCR和蛋白质印迹法检测另外27只大鼠（每组6只）海马中Cx 36、Cx32和Cx26的mRNA和蛋白表达。
与对照组相比，2-VO 3周组缝隙连接细胞膜密度降低，缝隙连接间隙增大，而这些异常在2-VO 8周和12周组逐渐改善。三个2-VO组中Cx36和Cx32的mRNA和蛋白水平在2-VO 3周组最低，然后逐渐升高，但均显著低于对照组（均P < 0.05）。Cx26的mRNA水平无明显改变，而三个2-VO组中Cx26的蛋白表达水平均高于对照组（均P < 0.05）。
神经元缝隙连接的改变可能参与慢性脑灌注不足所致的认知功能障碍。
