5-HT1A受体拮抗剂对七氟烷致老年认知功能障碍模型大鼠突触可塑性的作用及其机制OACSTPCD

Objective To investigate the effect of the 5-HT1A receptor antagonist on synaptic plasticity in flurane-induced cognitive dys-function in aged rats.Methods Thirty 18-month-old Sprague-Dawley rats were randomly divided into control,model,and drug groups.The model group inhaled a 50%oxygen gas mixture(2 L/min)and 2%sevoflurane and were then treated with 5μL 0.9%NaCl;the drug group inhaled a 50%oxygen mixture(2 L/min)and 2%sevoflurane for 4 h and then the 5-HT1A receptor antagonist(3μg)was injected into the left ventricles of the rats;and the control group inhaled a 50%oxygen mixture(2 L/min)for 4 h.The water maze method was used to assess the learning memory of the rats and histopathological changes in the rat hippocampus were examined by HE staining.Nissl and Golgi staining were used to identify any changes to the neurons and synapses in hippocampal tissue.The MeCP2,p250GAP,PSD-95,GAP-43,and Syn expression levels were determined by immunofluorescence assay and the PKA,CREB1,and BDNFmRNA levels were determined using real-time PCR.Western blotting was performed to determine the PKA,CREB1,p-CREB1,and BDNF expression levels.Results The water maze data showed that the escape latency was significantly prolonged in the model group compared to the control group and,after treatment with the 5-HT1A receptor antagonist,the escape latency significantly decreased in the drug group compared to that of the model group(P<0.05).Moreover,the number of platform crossings was significantly lower in the model group than in the control group,but the number of platform crossings in the drug group was significantly higher than that in the model group(P<0.05).Compared to the control group,the hippocampal neurons in the model group had irregular morphology,loosely arranged and enlarged sur-rounding tissue gaps,deeply stained nuclei,a reduced number of Nissl bodies in the neurons,and a significantly reduced dendritic spine density and number of branches.After treatment with the 5-HT1A receptor antagonist,the hippocampal neurons in the drug group had a regular morphology,relatively complete structure,uniform arrangement,increased numbers of Nissl bodies in the neurons,and a signifi-cantly increased dendritic spine density and number of dendritic branches.Compared to the control group,MeCP2,PSD-95,GAP-43,Syn,PKA,CREB1,p-CREB1,and BDNF expression levels significantly decreased and p250GAP expression significantly increased in the rat brain tissue from the model group(P<0.05),but the PKA,CREB1,and BDNF mRNA levels significantly decreased(P<0.05).Furthermore,compared to the model group,the MeCP2,PSD-95,GAP-43,Syn,PKA,CREB1,p-CREB1,and BDNF expres-sion levels significantly increased along with the PKA,CREB1,and BDNF mRNA levels(P<0.05)in the drug group.However,the p250GAP protein expression level significantly decreased(P<0.05).Conclusion The 5-HT1A receptor antagonist improves learning memory in rats with sevoflurane-induced cognitive dysfunction.Specifically,it enhances PSD-95,GAP-43,and Syn expression levels,pro-motes synaptic remodeling,and protects rat hippocampal neuronal cells by activating the CREB/BDNF pathway.