ObjectiveThis study aims to investigate the effect of Liuwei Dihuangwan on the autophagy function in the hippocampus of senescence-accelerated mouse prone 8 （SAMP8） by regulating the expression of glycoprotein non-metastatic melanoma protein B （GPNMB）. Furthermore， it is designed to explore the mechanism of the method of tonifying the kidneys and replenishing essence in the treatment of Alzheimer's disease （AD）. MethodsIn experiment 1， 24 5-month-old SAMP8 mice were randomly and equally divided into the model group， and the low-， middle- and high-dose（0.59，1.18，2.36 g·kg^-1） Liuwei Dihuangwan groups. At the same time， six 5-month-old senescence accelerated mouse resistant 1 （SAMR1） mice were used as the control group. The learning and memory ability was evaluated through novel object recognition experiment. Serum cortisol （Cort）， adrenocorticotropic hormone （ACTH） and urine 17-hydroxycorticosteroid （17-OHCS） levels were detected by enzyme-linked immunosorbent assay （ELISA）. The ultrastructure of hippocampal neurons was observed by transmission electron microscope （TEM）， and the expression levels of hippocampal GPNMB， a disintegrin and metalloproteinase 10 （ADAM10） and autophagy-related proteins were detected by Western blot. In experiment 2， 18 SAMP8 mice were randomly and equally divided into the model group， vector control group （Vector）， and GPNMB overexpression group （GPNMB^OE）. Lentiviral vectors were stereotactically injected into the brain （2 μL per side in the GPNMB^OE group）. Western blot was used to detect the expression of the above target proteins in the hippocampus； In Experiment 3， 24 SAMP8 mice were randomly and equally divided into the model group， Liuwei Dihuangwan group， Liuwei Dihuangwan+negative control （NC） group， and Liuwei Dihuangwan+GPNMB silencing group （shGPNMB）. Before drug treatment， the Liuwei Dihuangwan+NC group and the Liuwei Dihuangwan+shGPNMB group were injected with negative control and GPNMB silencing lentivirus， respectively. Western blot was used to detect the expression of the above target proteins in the hippocampus. ResultsThe novel object discrimination index of mice in the model group was significantly lower than that of mice in the control group （P<0.01）. The novel object discrimination index of mice in the medium- and high-dose Liuwei Dihuangwan groups was significantly higher than that of mice in the model group （P<0.01）. Aggregated autolysosomes were observed in the normal hippocampus tissue by TEM. In the model group， mitochondria were dominant， and no typical characteristic autophagosomes were observed. In the low- and medium-dose Liuwei Dihuangwan groups， a small number of autolysosomes and autophagosomes with double-membrane structures were observed. In the high-dose Liuwei Dihuangwan group， the number of autophagosomes and autolysosomes was greater than that in the low- and medium-dose groups. The results of ELISA and Western blot showed that compared with the control group， the levels of serum Cort， ACTH， and urine 17-OHCS in the model group were substantially increased， while the expression of hippocampal ADAM10， Beclin1， and microtubule associated-protein light chain 3-Ⅱ/Ⅰ （LC3 Ⅱ/Ⅰ） was significantly decreased. The expression of GPNMB and ubiquitin binding protein p62 was significantly increased （P<0.05， P<0.01）. Compared with the model group， the serum Cort and ACTH levels in the low-， medium-， and high-dose Liuwei Dihuangwan groups were significantly reduced， while only the urine 17-OHCS level in the high-dose group was significantly reduced. The hippocampal GPNMB， ADAM10， Beclin1， and LC3 Ⅱ/Ⅰ expression levels in the medium-， and high-dose groups of Liuwei Dihuangwan were significantly increased compared to the model group， whereas the expression of p62 was significantly reduced （P<0.01）. The above indicators showed a progressive trend among the three groups. Compared with the model group， the GPNMB^OE group showed a significant increase in GPNMB， ADAM10， Beclin1， LC3 Ⅱ/Ⅰ expression， and a significant decrease in p62 expression （P<0.01）. Compared with the model group， the expression of GPNMB， ADAM10， Beclin1， and LC3 Ⅱ/Ⅰ in the hippocampus of the Liuwei Dihuangwan group significantly increased， while the expression of p62 significantly decreased （P<0.01）. Compared with the Liuwei Dihuangwan group， the Liuwei Dihuangwan+shGPNMB group showed a significant decrease in GPNMB， ADAM10， Beclin1， LC3 Ⅱ/Ⅰ， and a significant increase in p62 expression （P<0.01）. ConclusionLiuwei Dihuangwan can enhance hippocampal autophagy function and improve AD by upregulating GPNMB expression.