Objective:

2

To explore the mechanism of Dihuang Yinzi (DHYZ) in the treatment of Alzheimer's disease (AD) by integrating metabolomics and experimental verification.

Methods:

2

Forty-eight male APP/PS1 mice were divided into model

high- (DHYZ-H)

medium- (DHYZ-M)

and low-dose DHYZ (DHYZ-L) groups (12 mice per group) according to a random number table. Mice in DHYZ groups were gavaged with DHYZ 6.34

12.68

and 25.35 g/(kg•d)

respectively. Twelve C57BL/6 mice were gavaged with distilled water as the blank group. Metabolomics was used to analyze differential metabolites in the brains of mice. Morris water maze test was used to detect the memory abilities of mice. The hematoxylin-eosin staining and transmission electron microscopy were used to observe the general morphology and ultrastructure of neurons. The enzyme-linked immunosorbent assay was used to detect the levels of superoxide dismutase (SOD)

reactive oxygen species (ROS)

and amyloid β-protein 1–42 (Aβ

1-42

). The real-time quantitative polymerase chain reaction was used to detect the mRNA expressions of density-regulated protein 1 (DRP1)

fission 1 (FIS1)

mitofusin-1 (MFN1)

and optic atrophy protein 1 (OPA1). Western blot was used to detect the protein expressions of cyclic adenosine monophosphate (cAMP)

protein kinase A (PKA)

cAMP response binding protein (CREB)

brain-derived neurotrophic factor (BDNF)

synapsin 1 (SYN1)

synaptophysin (SYP)

and postsynaptic density protein 95 (PSD95).

Results:

2

A total of 82 differential metabolites were identified in the brains of APP/PS1 mice

among which 7 differential metabolites could be regulated by DHYZ. After DHYZ intervention

the memory abilities of mice significantly increased (

P

<

0.05 or

P

<

0.01)

the number of synapses and neurons in the hippocampus increased

and the mitochondrial morphology and structure were relatively intact. The DHYZ groups exhibited a significant reduction in hippocampal ROS and Aβ

1-42

levels

along with a significant elevation in SOD level (

P

<

0.05 or

P

<

0.01). The mRNA expressions of DRP1 and

FIS1 were reduced

while the mRNA expressions of MFN1 and OPA1 were increased after DHYZ treatment (

P

<

0.05 or

P

<

0.01). The cAMP/PKA/CREB-BDNF pathway was activated

and the expressions of SYN1

SYP and PSD95 proteins were significantly increased in the DHYZ-H group (

P

<

0.05 or

P

<

0.01).

Conclusions:

2

DHYZ could improve mitochondrial dynamics and synaptic plasticity in APP/PS1 mice

inhibit oxidative stress

and thereby enhancing learning and memory abilities in APP/PS1 mice. Its mechanism might be related to activation of the cAMP/PKA/CREB-BDNF signaling pathway.