Mechanism of Linggui Zhugantang in Promoting Astrocyte Endocytosis and Degradation of Amyloid β / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo investigate the effects of Linggui Zhugantang （LGZGT）-containing serum on primary astrocytes （AS） induced by β amyloid 1-42 （Aβ1-42） in a rat model of Alzheimer's disease （AD） and explore the phagocytic and degradative effects of LGZGT on Aβ. MethodAn AD model was established by inducing AS with Aβ1-42. The cells were divided into normal group， model group， LGZGT low-， medium-， and high-dose （LGZGT-L， LGZGT-M， and LGZGT-H） groups， and donepezil hydrochloride group. The model group was treated with Aβ1-42 at a final concentration of 10 μmol∙L-1. The LGZGT-L， LGZGT-M， and LGZGT-H groups were treated with 10% serum containing LGZGT on the basis of the model group. Cell viability was assessed using a cell counting kit-8 （CCK-8）， lactate dehydrogenase （LDH） activity was measured using an LDH assay kit， and cell morphology was observed using an inverted microscope. The expression of Aβ-related degradation enzymes insulin-degrading enzyme （IDE） and cathepsin D （CTSD） was detected using Western blot， and the fluorescence intensity of cathepsin B （CTSB） was measured using immunofluorescence. The content of Aβ1-42 in cells was determined using an enzyme-linked immunosorbent assay （ELISA）. ResultCompared with the normal group， the viability of AS in all groups decreased， and Aβ1-42 at different concentrations had inhibitory effects on AS proliferation. After administration， compared with the normal group， the cell survival rate of the model group decreased significantly （P<0.05）. Compared with the model group， the cell survival rates of the LGZGT-H group and donepezil hydrochloride group increased significantly （P<0.05）. The LDH activity of cells in the model group was significantly increased compared with that in the normal group （P<0.05）， and cell bodies were swollen and enlarged with increased protrusions and elongation， suggesting more obvious cell damage. Compared with the model group， the LDH activity of cells in the donepezil hydrochloride， LGZGT-L， LGZGT-M， and LGZGT-H groups decreased significantly （P<0.05）. After administration， the cell swelling in the LGZGT-M， LGZGT-H， and donepezil hydrochloride groups improved， cell protrusions shortened， and cell clustering decreased. Compared with the normal group， the expression of IDE and CTSD in the model group decreased significantly （P<0.05）. Compared with the model group， the expression of IDE increased significantly in the LGZGT-M and LGZGT-H groups （P<0.05）. Compared with the model group， the expression of CTSD increased significantly in the LGZGT-L， LGZGT-M， LGZGT-H， and donepezil hydrochloride groups （P<0.05）. The average fluorescence intensity of CTSB in the model group was significantly lower than that in the normal group （P<0.05）. Compared with the model group， the average fluorescence intensity of CTSD in the LGZGT-L， LGZGT-M， LGZGT-H， and donepezil hydrochloride groups increased significantly （P<0.05）. The intracellular content of Aβ1-42 in cells in the model group was significantly higher than that in the normal group （P<0.05）. After administration， compared with the model group， the intracellular content of Aβ1-42 in cells in the LGZGT-L， LGZGT-M， LGZGT-H， and donepezil hydrochloride groups decreased significantly （P<0.05）， and LGZGT-containing serum reduced Aβ1-42 in a dose-dependent manner （P<0.05）. ConclusionLGZGT has a protective effect on Aβ1-42-induced AS and can promote the degradation of Aβ. Its mechanism may be related to reducing Aβ toxicity， enhancing cell viability， promoting the expression of IDE， CTSD， and CTSB， and restoring lysosomal function.