Hei Xiaoyaosan Regulates Fas/FasL/Caspase-8/Caspase-3 Signaling Pathway to Inhibit Neuronal Apoptosis in AD Rats / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the effect and mechanism of Hei Xiaoyaosan in regulating the tumor necrosis factor receptor superfamily member 6 （Fas）/Fas ligand （FasL）/cysteine protease-8 （Caspase-8）/cysteine protease-3 （Caspase-3） signaling pathway to intervene in neuronal apoptosis and prevent Alzheimer's disease （AD）. MethodNinety SPF-grade SD male rats of 4 months old were selected and randomly grouped as follows： 10 rats in the blank group， 10 rats in the sham group （bilateral hippocampus injected with 1 μL normal saline）， and 70 rats in the modeling group ［bilater hippocampus injected with 1 μL amyloid-beta protein 1-42 （Aβ1-42） solution for the modeling of AD］. Fifty successfully modeled rats were selected and randomly assigned into model， donepezil hydrochloride （0.45 mg·kg-1）， and high-， medium-， and low-dose （15.30， 7.65， 3.82 g·kg-1） Hei Xiaoyaosan groups. Rats were administrated with corresponding agents by gavage once a day for 42 days. Terminal-deoxynucleoitidyl transferase-mediated nick end labeling （TUNEL） was employed to observe the apoptosis of neurons in the cortex and hippocampus， and immunohistochemistry （IHC） was used to detect the expression of B-cell lymphoma-2 （Bcl-2） and Bcl-2-associated X protein （Bax） in the hippocampus. Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） was employed to determine the mRNA levels of Fas， FasL， and Fas-associated protein with death domain （Fadd）. Western blot was used to determine the protein levels of Fas， FasL， Fadd， Caspase-3， cleved Caspase-3， Caspase-8， and cleved Caspase-8. ResultCompared with the blank group and sham group， the model group showed increased apoptosis rate in the cortex and hippocampus （P<0.01）， elevated Bax level （P<0.01）， lowered Bcl-2 level （P<0.01）， up-regulated mRNA levels of Fas， FasL， and Fadd in the hippocampus （P<0.01）， and up-regulated protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.01）. Compared with the model group， donepezil hydrochloride and Hei Xiaoyaosan at high and medium doses decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bax level （P<0.01）， elevated the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of Fas， FasL， and Fadd and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05， P<0.01） in the hippocampus. Low-dose Hei Xiaoyaosan decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of FasL and Fadd （P<0.05） and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05） in the hippocampus. ConclusionHei Xiaoyaosan can protect neurons in the cortex and hippocampus of AD rats by inhibiting the apoptosis mediated by the Fas/FasL/Caspase-8/Caspase-3 signaling pathway.