This study aims to explore the impact of
Huangqisan on synaptic plasticity in rat model of Alzheimer′s disease and to
analyzed its potential mechanism.Fifty SPF grade male SD rats were randomly
divided into normal group (Norm),model group (Mod),Huangqisan low dose group
(HQS-L,1.2 g/kg),Huangqisan high dose group(HQS-H,4.8 g/kg) and positive group
(Pos),with 10 rats in each group.Except for the normal group,the rats in other
groups were injected with β-amyloid
25-35 into bilateral hippocampal to establish the model.Morris water maze test
was used to detect the learning and memory function of the rats.Nissl staining
was used to detect neuronal damage in hippocampus of rats.JC-1 probe was
applied to detect the mitochondrial membrane potential in hippocampus by flow
cytometry.Transmission electron microscope was used to detect the
ultrastructural observation of neurons and synapses in rat hippocampus.ELISA
was performed to measure the levels of pro-inflammatory cytokines interleukin-1β (IL-1β),interleukin-6 (IL-6),and tumor necrosis factor-α (TNF-α) in the rat hippocampus.Flow cytometry was used to detect the
level of hippocampus reactive oxygen species (ROS).The expressions of
PTEN-induced kinase 1 (PINK1),Parkin E3 ubiquitin protein ligase
(Parkin),microtuble-associated protein light chain 3 (LC3B),ubiquitin-binding
protein p62 (p62),dynamin-related protein (Drp1),mitofusion 1 (Mfn1),mitofusion
2 (Mfn2),NOD-like receptor protein 3 (NLRP3),growth-associated protein 43
(GAP43),N-methyl-D-aspartate receptor (NMDAR) subunit 2B (NR2B),postsynaptic
dense protein 95 (PSD95),synaptosin (SYP) and brain-derived neurotrophic factor
(BDNF) proteins in the hippocampus were detected by Western blot (WB).Compared
with Norm group,the learning and memory function of rats in the Mod group was
significantly reduced(P<0.01).Nissl
bodies in neurons of hippocampus decreased or disappeared.The ultrastructure of
neurons and synapses in hippocampus presented obvious pathological
changes.Mitochondrial membrane potential decreased significantly and the
structure was damaged,autolysosome has formed.The contents of IL-1β,IL-6 and TNF-α in hippocampus increased significantly (P<0.01),the level of ROS increased significantly(P<0.01),the protein expression of
PINK1,Parkin,LC3B,Mfn1,Mfn2,GAP43,NR2B,PSD95,SYP and BDNF decreased
significantly(P<0.05),and the
protein expression of p62,Drp1,NLRP3 increased significantly(P<0.01).Compared with Mod group,the
learning and memory function of AD rats improved significantly in the HQS-L
group,HQS-H group and Pos group,which was mainly manifested by shortened the
escape latency and elevated the number of crossing the platform (P<005,P<0.01).Nissl bodies in neurons of hippocampus increased,the
ultrastructure of neurons and synapses in hippocampus was improved,the
mitochondrial membrane potential was increased,and the mitophagy was
increased.The contents of IL-1β,IL-6
and TNF-α in hippocampus decreased
significantly (P<0.05,P<0.01),the level of ROS decreased
significantly(P<0.01),the protein
expression of PINK1,Parkin,LC3B,Mfn1,Mfn2,GAP43,NR2B,PSD95,SYP and BDNF
increased significantly,and the protein expression of p62,Drp1,NLRP3 decreased
significantly (P<0.05,P<0.01).The mechanism of Huangqisan
improved synaptic plasticity in AD rats might be related to the activation of
PINK1-Parkin pathway in hippocampus to promoted mitophagy,improved
mitochondrial function,reduced ROS level and inhibited the activation of NLRP3
inflammasome.
