ABSTRACT
Objective To observe the changes of hippocampal NogoA-NgR1 signaling on postoperative cognitive function (POCD) in aged mice, and explore the potential underling mechanism.Methods Isoflurane anesthesia and laparotomy were applied to establish the POCD model.Forty aged male C57BL/6 mice were randomly divided into the following four groups (n=10): group O2+saline (group OS), group O2+NEP1-40 (group ON), group isoflurane anesthesia+laparotomy surgery+saline (group SS), and group isoflurane anesthesia+laparotomy surgery+NEP1-40 (group SN).Cannula placement was performed into lateral ventricle 7 days before the surgery.Animals were subjected to an administration of NEP1-40 (20 μg/2 μl) or isochoric saline via intracerebroventricular injection once daily for 8 consecutive days, injection was given from 2 h before isoflurane anesthesia to the last behavioral test.Open field test was performed at 5th d after operation.Contextual and cued fear conditioning training and testing were exhibited at 6th and 7th d after operation, respectively.The hippocampus was harvested 2 h after the behavioral test.Western blot was used to detect the expressions of NogoA, NgR1, RhoA, ROCK2 and GAP43.Golgi staining was applied to measure the changes of dendritic spines in hippocampal CA1 area.Results Compared with the groups OS and ON, the freezing time in the contextual fear conditioning test was significantly decreased, the contents of NogoA, NgR1, RhoA and ROCK2 were significantly increased, the content of GAP43 and the number of dendritic spine were significantly decreased in group SS (P<0.05).Compared with the group SS, the freezing time in the contextual fear conditioning test was significantly increased, the contents of RhoA and ROCK2 were significantly decreased, the content of GAP43 and the number of dendritic spine were significantly increased in group SN (P<0.05).Conclusion Over-activated of hippocampal NogoA-NgR1 signaling participated in the pathogenesis of POCD in aged mice.