[Differences of brain pathological changes and cognitive function after bilateral common carotid artery occlusion...

The aim of the present study was to investigate the differences of the pathological changes and cognitive function after bilateral common carotid artery occlusion (BCCAO) between Sprague-Dawley (SD) and Wistar rats. Male SD and Wistar rats were randomly divided into 2 groups, respectively: sham operated (S-sham and W-sham) and operated (S-BCCAO and W-BCCAO) groups. The survival rate and the rate of loss of pupillary light reflex (PLR) were observed on day 1, 3, 7, 14 and 28 after the operation, and the light-dark box, Y-maze and odor recognition tests were performed to detect cognitive function on day 28 after the operation. HE and Luxol fast blue staining were used to observe the pathological changes of gray matter (hippocampus), white matter (optical tract), optic nerve, and retina. The results showed that the survival rate of the W-BCCAO group was 62.5%, and PLR loss rate was 100%; whereas the survival rate of the S-BCCAO group was 100%, and PLR loss rate was 58.3%. In the W-BCCAO group, percentages of time spent and distance traveled in the light box were more than those in the W-sham group, but there was no statistical significance between the S-BCCAO and S-sham groups. In the S-BCCAO group, the percentages of time spent and distance traveled in the III arm (labyrinth arm) of the Y-maze were less than those in the S-sham group, but no statistical significance was found between the W-BCCAO group and W-sham group. In the S-BCCAO group, the discrimination ratio of the odor recognition task was less than that in the S-sham group, but no statistical significance could be seen between the W-BCCAO and W-sham groups. Ischemic injury was observed in the CA1 area of the hippocampus in the S-BCCAO group, but no readily visible damage was observed in the W-BCCAO group. Ischemic injury of the visual beam and optic nerve was observed in both the S-BCCAO and W-BCCAO groups. Compared with the corresponding sham groups, the S-BCCAO and W-BCCAO groups showed serious retinal damage with significant thinner retina. The ganglion cell layer (GCL), inner plexiform layer (IPL), and outer plexiform layer (OPL) were thinner in the S-BCCAO group, but no statistical significances were shown in the other layers. All the layers, except the outer nuclear layer (ONL), were significantly thinner in the W-BCCAO group. The results indicate that there are differences of the pathological changes in the hippocampus and visual conduction pathway after BCCAO between SD and Wistar rats, and the degree of learning and memory injury was also different, which suggests that the vascular dementia model of different rat strains should be selected according to research purpose.