| Objective: Given tyrosine kinase B(Trk B)receptor agonists or blockers to interfere with perioperative neurocognitive impairment animal models of elderly SD rats.The de-ndritic spines density of neurons in hippocampal CA1 area,and the expression levels of the brain derived neurotrophic factor(BDNF),Trk B and postsynaptic density protein95,synaptophysin,in hippocampal tissue were all observed.The changes of cognitive functio-nwere also evaluated to probe the possible mechanismof cognitive dysfunction in elderly SD rats,which are induced by sevoflurane.Methods: Thirty-six18-month-old SPF SD rats were randomly divided into blankcontrol group(group C),sevoflurane group(group S),agonistgroup(group A)and blockergroup(group B).Rats in groups S,A,B and C were treated with 3% sevoflurane and 50% air oxygen mixturefor 2h,respectively.Morris water maze experiment was performed on6 days before modeling and 1 day after modeling.By analyzing the collected swimming data of SD rats,the successof modelingwas judged.On the 1st day,3rd day and 7th day after administration,3 rats in each group were randomly selected at each time.The exp-ressionsof BDNF,Trk B,PSD-95 and SYP in hippocampus were examined by Western Blot and real-time PCR.The number of dendriticspines per unit length was analyzed by Golgi staining in the CA1 region of hippocampus.Results: 1.Behavioral test results showed that :(1)In comparison with group C,after1 and 3 days drug intervention,the escape latency(referred to: Tl)and the total swimmi-ng distance(referred to: Sp)of rats in groups S,A and B were prolonged,the count of acrossing platform(referred to: Cp)and residencetime in quadrant for placing the platf-orm(referred to: Tp)were decreased,(P<0.05).After 7 days drug intervention,Tl and Sp were significantly shortened,Cp and Tp were significantly increased in group A,(P<0.05),while the results of rats in group S were not outstanding changed.In group B,Tl and Sp were gradually prolonged,Cp and Tp were gradually decreased after administration(P<0.05).(2)Compared with group S: after 1,3 and 7 days of drug intervention,Tl and Spwere shortened in group A,while Cp and Tp were increased.Even more surprising is that the Tl and Splengthened,Cp and Tpdecreased in group B after intervention,(P< 0.05).2.Molecular biological detection results:(1)Compared with group C: the expressions of BDNF and Trk B in groups A,B and S were down-regulated after administration1 and 3days,and there was no difference after administration7 days.The expression of SYP and PSD95 in group A gradually up-regulated after administration,and were more significantly after 3 and 7 days.It was still lower in group S and B after administration 1and 3 days,and more obvious in group B after 7 days,(P<0.05),but no difference in group S.(2)Compared with group S: after administration 1,3 and 7 days,the expressions of SYP and PSD95 were gradually up-regulated in group A and gradually down-regulated in group B,(P<0.05).3.Golgi staining analysis showed that:(1)Compared with group C,the density of dendri-tic spinodes in the CA1 area in group S was lower 1d and 3d after administration,and no remarkable change was observed 7d after administration;Group A was significantly increased after 3 and 7 days administration;Group B was significantly reduced after administration;(2)Compared with group S: After 1d,3d and 7d of drug treatment,the density of dendritic spines in the CA1 area of hippocampal tissue of rats increased significantly in group A and decreased significantly in group B.Conclusion: Cognitive impairmentin aged rats after continuousinhalation of sevoflurane is associated with synaptic plasticity damage in hippocampal neurons caused by abnormal BDNF/Trk B signaling pathway,and this damage can be reversed by 7,8-dihydroxyflavone. |
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