基于EphA4/ephrinA3信号通路探讨安寐丹改善老年睡眠剥夺模型神经元突触结构功能损伤的作用OA

Objective:To investigate the effects of Anmeidan(AMD)on protein expression of the ephrin type-A receptor 4(EphA4)/ephrinA3 signaling pathway and synaptic structural function in an aged sleep deprivation model.Methods:Seventy-two 18-month-old aged mice were randomly divided into a blank group,a model group,AMD high-,medium-,and low-dose groups(26.26,13.13,6.565 g·kg-1·d-1,respectively),and a melatonin group(1.3 mg·kg-1·d-1),with 12 mice in each group.Cognitive function was assessed using the novel object recognition test.Hematoxylin-eosin(HE)staining was used to observe cell number and morphology in hippocampal tissues,and Nissl staining was performed to examine cellular structure and quantify Nissl bodies.Transmission electron microscopy was used to observe synaptic ultrastructure,with emphasis on changes in synaptic morphology and structure.Western blot was employed to detect the expression levels of EphA4,ephrinA3,brain-derived neurotrophic factor(BDNF),glutamate aspartate transporter(GLAST),glutamate transporter-1(GLT-1),growth-associated protein 43(GAP43),postsynaptic density protein 95(PSD95),and synaptophysin(SYN)in hippocampal tissues.Immunofluorescence double labeling was performed to co-stain EphA4 and ephrinA3 with glial fibrillary acidic protein(GFAP)and neuronal nuclei antigen(NeuN),respectively,to observe the colocalization of target proteins with neurons and astrocytes.Results:Compared with the blank group,the model group exhibited increased exploration time of familiar objects(P＜0.01),while exploration time of novel objects and the recognition index were decreased(P＜0.01).The number of neurons in the CA1,CA3,and dentate gyrus(DG)regions of the hippocampus was reduced,Nissl bodies were decreased,and synaptic structures were damaged.Protein expression levels of BDNF,GLAST,GLT-1,GAP43,PSD95,and SYN in hippocampal tissues were decreased,whereas the expression levels of EphA4,ephrinA3,and GFAP were increased.Compared with the model group,the AMD low-,medium-,and high-dose groups and the melatonin group showed increased exploration time of novel objects and higher novel object recognition indices(P＜0.01),along with significantly reduced exploration time of familiar objects(P＜0.01).Neuronal damage in the CA1 and DG regions was ameliorated,the number of Nissl bodies in the CA1 region was increased,and organelle and synaptic structural damage was alleviated.Protein expression levels of BDNF,GLAST,GLT-1,GAP43,PSD95,and SYN were increased,and protein expression levels of EphA4,ephrinA3,and GFAP were decreased(P＜0.05,P＜0.01).Conclusion:AMD can regulate protein expression of the EphA4/ephrinA3 signaling pathway in an aged sleep deprivation model,enhance synaptic protein expression,and improve neuronal synaptic damage.