Effects of triptolide on neuronal apoptosis of hippocampus in AD model rats

Objective To explore the effect of triptolide(TP) on the neuronal apoptosis and the expression of apoptosis-related proteins in hippocampus of AD model rats. Methods Healthy male SD rats were randomly divided into control,AD model and TP-treated groups. The AD model group was made by bilateral microinjection of Aβ1-40 into hippocampus in rats and Morris water maze test was used to judge the models success or not. The control group was made by bilateral microinjection of normal saline into hippocampus in rats.The TP-treated group rats were administered TP (0.4 mg·kg-1·d-1) intraperitoneally after the AD model was made successfully. 15 days later,the changes of neuronal apoptosis in hippocampus of each group were observed with flow cytometry and TUNEL staining and transmission electron microscopy,and the changes of cytochrome C and Bcl-2 protein expression in hippocampus of each group were observed by immunohistochemical staining. Results Compared with those of the AD model group,the apoptosis rate of neurons and the cell number of TUNEL positive staining in hippocampus of the TP-treated group were significantly decreased(P0.01). The number and average optical density of cytochrome c positive products in hippocampus of the TP-treated group were obviously lower than those of the AD model group (P0.01),and the cell number and average optical density of Bcl-2 positive staining were obviously higher than those of the AD model group (P0.01). Conclusions TP can inhibit the neuronal apoptosis in hippocampus of the AD model group.Its mechanism may concern increasing the Bcl-2 expression and reducing the release of cytochrome c in hippocampus of the AD model group.