[Protective effect of Anmeidan on hippocampal neuronal damage and synaptic microenvironment in sleep-deprived rats based on NRG1/ErbB4 signaling pathway]

This study aims to investigate the effect of Anmeidan on hippocampal neurons and synaptic microenvironments in sleep-deprived rats. Sixty SD rats were randomly divided into blank, model, Anmeidan, and melatonin groups, with 15 rats in one group. The study used the multi-platform method to prepare the sleep deprivation model. A dosage of 18.18 g·kg~(-1)·d~(-1) was administered to the Anmeidan group, a dosage of 100 mg·kg~(-1)·d~(-1) to the melatonin group, and pure water to the blank and model groups. All rats were administered by gavage for 4 weeks. The spontaneous activity of rats was assessed by using a behavioral analysis system. Hip-pocampal pyramidal neurons and Nissl bodies were observed by Nissl staining. Neuronal apoptosis was observed by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling(TUNEL) staining. The ultrastructure of synaptic was observed by transmission electron microscopy, and dendritic spine changes were observed by Golgi staining. The expression of glial fibrillary acidic protein(GFAP), γ-aminobutyric acid A(GABAA), glutamate receptor N1(GLUN1), postsynaptic density-95(PSD95), synaptophysin(SYP), brain-derived neurotrophic factor(BDNF), and nerve growth factor(NGF) were detected by immunofluorescence staining. The expression of neuregulin 1(NRG1), epidermal growth factor receptor(ErbB4), glutamate receptor A1(GLUA1), GLUN1, and glutamate receptor N2A(GLUN2A) were detected by Western blot. While compared with the blank group, the results showed that the model group had a significant decrease in the horizontal score, vertical score, modified times, ratio of the central region, a decline in the number of hippocampal pyramidal cells and Nissl bodies, and an increase in the apoptotic index. The expression of NRG1, ErbB4, GLUA1, GLUN1, and GLUN2A proteins was down-regulated, and the positive expression of GFAP~+/GABAA~+ and GFAP~+/GLUN1~+ was decreased. The fluorescence intensity of PSD95, SYP, BDNF, and NGF decreased, and the synaptic vesicle density was uneven. Synaptic interface curvature and postsynaptic density thickness reduced, and dendritic spines decreased. Compared with the model group, the Anmeidan group showed an increase in the horizontal score, the vertical score, the modified times, the central area path ratio, the pyra-midal cells and Nissl bodies, while the apoptotic index decreased. The expression of NRG1, ErbB4, GLUA1, GLUN1, and GLUN2A was up-regulated, and that of GFAP~+/GABAA~+ and GFAP~+/GLUN1~+ was increased. The fluorescence intensities of PSD95, SYP, and BDNF, NGF were increased, and synaptic damage was reduced. The results indicated that the mechanism of Anmeidan in ameliorating hippocampal neuronal damage in sleep-deprived rats may be related to the up-regulation of the NRG1/ErbB4 pathway, the promotion of glutamate receptors, neurotrophic factor, and synaptic protein expression which improved the synaptic microenvironment.