Objective

2

To observe the therapeutic effect of Qiwei Baizhusan（QWBZS） on diabetic encephalopathy（DE） rat model， and to explore the possible mechanism of QWBZS in the treatment of DE based on phosphatidylinositol 3-kinase（PI3K）/protein kinase B（Akt）/glycogen synthase kinase-3

β

（GSK-3

β

） signaling pathway.

Method

2

Forty-eight SPF male Wistar rats were randomly divided into blank group（8 rats） and high-fat diet group（40 rats）. After 12 weeks of feeding， rats in the high-fat diet group were intraperitoneally injected with 35 mg·kg

-1

of 1% streptozotocin（STZ） for 2 consecutive days to construct a DE model， and rats in the blank group were injected with the same amount of sodium citrate buffer. After successful modeling， according to blood glucose and body weight， model rats were randomly divided into model group， low， medium and high dose groups of QWBZS（3.15， 6.3， 12.6 g·kg

-1

）， combined western medicine group（metformin+rosiglitazone， 0.21 g·kg

-1

）， with 6 rats in each group. The administration group was given the corresponding dose of drug by gavage， and the blank group and the model group were given an equal volume of 0.9% sodium chloride solution by gavage， 1 time/day for 6 weeks. Morris water maze was used to detect the spatial memory ability of DE rats. Fasting insulin （FINS） level was detected by enzyme-linked immunosorbent assay（ELISA） and insulin resistance index（HOMA-IR） was calculated. Hematoxylin-eosin（HE） staining was used to observe the morphological changes of hippocampus in rats， ELISA was used to detect the indexes of oxidative stress in hippocampal tissues， real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） was used to detect mRNA expression levels of PI3K， Akt， nuclear transcription factor-

κ

B（NF-

κ

B）， tumor necrosis factor-

α

（TNF-

α

） and interleukin-1

β

（IL-1

β

） in hippocampus， and Western blot was used to detect the protein expression of PI3K， Akt， phosphorylated（p）-Akt， GSK-3

β

and p-GSK-3

β

in hippocampus of rats.

Result

2

Compared with the blank group， FINS and HOMA-IR values of the model group were significantly increased（

P

<

0.01）， the path of finding the original position of the platform was significantly increased， and the escape latency was significantly prolonged（

P

<

0.01）， the morphology of neuronal cells in hippocampal tissues was disrupted， the levels of reactive oxygen species（ROS） and malondialdehyde（MDA） in hippocampus of rats were increased， and the activity of superoxide dismutase（SOD） was decreased（

P

<

0.05，

P

<

0.01）， mRNA expression levels of PI3K and Akt were decreased（

P

<

0.01）， mRNA expression levels of NF-

κ

B， TNF-

α

and IL-1

β

were increased（

P

<

0.05，

P

<

0.01）， the protein expression levels of PI3K， p-Akt and p-GSK-3

β

were significantly decreased， and the protein expression of GSK-3

β

was significantly increased（

P

<

0.01）. Compared with the model group， the FINS and HOMA-IR values of the medium dose group of QWBZS and the combined western medicine group were significantly decreased（

P

<

0.01）， the path of finding the original position of the platform and the escape latency were significantly shortened（

P

<

0.01）， the hippocampal tissue structure of rats was gradually recovered， and the morphological damage of nerve cells was significantly improved， the contents of ROS and MDA in hippocampus of rats decreased and the level of SOD increased（

P

<

0.01）， the mRNA expression levels of PI3K and Akt were increased（

P

<

0.01）， and the mRNA expression levels of NF-

κ

B， TNF-

α

and IL-1

β

were decreased （

P

<

0.05，

P

<

0.01）， the protein expression levels of PI3K， p-Akt and p-GSK-3

β

were significantly increased（

P

<

0.01）， and the expression of GSK-3

β

was significantly decreased（

P

<

0.01）.

Conclusion

2

QWBZS can alleviate insulin resistance in DE rats， it may repair hippocampal neuronal damage and improve learning and cognitive ability of DE rats by activating PI3K/Akt/GSK-3

β

signaling pathway.