Effects Of Dexmedetomidine On Cognitive Function In Rats With Mild Cognitive Impairment

Backgrounds and Objectives To investigate the effect of dexmedetomidine on cognitive function after anesthesia and study its real mechanism by the establishment of mild cognitive dysfunction rat model,so as to provide a theoretical basis that the dexmedetomidine improve postoperative cognitive function on elderly.Methods Establishment of mild cognitive impairment rat mode: The Morris water maze was performed within 6 days after the injection.After the behavior test,the inhalation anesthesia began.Group A continued receiveing inhalation of 2% sevoflurane for 2h and intraoperative infusion of 0.9% normal saline with the concentration of 0.25ml·100g-1·h-1.Group B continued receiveing inhalation of 2% sevoflurane for 2h and intraoperative infusion of dexmedetomidine with the concentration of 10ug·kg-1.Group C was the control group without treatment.Control group only continued receiveing inhalation of 2% sevoflurane for 2h and intraoperative infusion of 0.9% normal saline with the concentration of 0.25ml·100g-1·h-1.After that,the Morris water maze was performed,then the levels of IL-1,IL-6 and TNF-αof brain homogenate were detected,and the pathomorphologic change of hippocampus was observed by HE staining.Results The survival rate of each group was 100%.Model establishment:1、Speed was lower.The escape latencies of group A,B,C were prolonged than that of control group.2、 numbers of crossing the platform in 60 s of group A,B,C were significantly reduced(P<0.05).Dexmedetomidine intervention:1、compared with group C,the escape latency of group A and B was prolonged(P < 0.05),which group A was more obvious;numbers of crossing the platform in 60 s of group A and B were reduced,but group A is more serious;while the escape latency and the number of cross platform of the control group has no significant change before and after inhalation anesthesia.(P > 0.05).2、Compared with control group,the levels IL-1,IL-6 and TNF-αof brain homogenate were elevated(P<0.05),but the group A was more significant,group B after.(P < 0.05).3、 The pathological observation showed that,in control group,pyramidal cells in CA1 region of hippocampus arranged closely,the density of cell is normal,cell structure is normal and cytoplasm structure is clear;in group A,B,C pyramidal cells in CA1 region of hippocampus all change.In group A,pyramidal cells was significantly decreased,rranged obviously loose and in a mess,density of cell was significantly decreased,more cells were condensed,dark-stained and apoptosis and there were obvious vacuoles in the cytoplasm in the cytoplasm.In group B,several pyramidal cells lost,density of cell was slightly decreased,pyknotic nucleis increased and some pyramidal cells were dark-stained and a small amount of cell apoptosis.In group C,the number and density of pyramidal cells was almost normal,only little pyramidal cells were dark-stained and little cell apoptosis.Conclusions Dexmedetomidine can inhibit the apoptosis of hippocampal cells and reduce the cognitive dysfunction of rats with mild cognitive impairment induced by D-galactose through inhibiting the release of inflammatory factors.