Effect of IcarisideII on spatial learning and memory impairments and axonal regeneration in rats induced by chronic cerebral hypoperfusion

Objective To observe the effect of IcarisideⅡ(ICSⅡ) on spatial learning and memory impairments and axonal regeneration induced by chronic cerebral hypoperfusion(CCH) in rats. Methods 90 male SD rats were randomly divided into normal group, sham operation group, CCH group and ICSⅡ low, middle and high-dose treatment groups.The chronic cerebral hypoperfusion model was established by permanent bilateral common carotid artery occlusion.Then these rats in ICSⅡ low, middle and high-dose treatment groups were given ICSⅡ4, 8 and 16 mg/(kg·d) by gavage on the 1st day after modeling.There were 5 rats in every group at each observing time(4, 8 and 12 week). Morris water maze experiment was utilized to assess the escape latency and the target quadrant residence time while HE and immunohistochemistry analysis were applied to test the morphology change and expressions of GAP-43, MAP-2 and Nogo-A in hippocampal CA1. Results Compared with those of sham operation groups at 4, 8 and 12 week respectively, the escape latency in CCH group were significantly prolonged(40.02±4.95)s, (42.29±5.75)s, (53.68±6.14)s vs (26.43±2.68)s, (26.84±2.06)s, (31.53±4.12)s, P 0.05). Compared with those in 8 week and 4 week, the escape latency and the target quadrant residence time were prolonged and reduced with the expression of Nogo-A increased in all groups except normal group and sham operation group(P 0.05). However, there were no statistical significance of all indexes between 8 week and 4 week(P>0.05). Conclusion ICSⅡ can improve the spatial learning and memory in chronic cerebral hypoperfusion rats, which may be achieved by neuroprotective effects and reducing the expression of Nogo-A consequently promotes the regeneration of axons. Key words: IcarisideⅡ; Chronic cerebral hypoperfusion; Spatial learning and memory impairments; Axonal regeneration; Rat