Objective

2

To investigate the mechanism of

Shaoyao Decoction

in treating ulcerative colitis （UC） in mice based on the Notch signaling pathway.

Methods

2

Fifty male C57BL/6 mice were randomly divided into five groups （

n

=10 for each group）： normal，model，low-dose，medium-dose，and high-dose

Shaoyao Decoction

groups. UC was induced by administration of DSS. Starting on day 4 of modeling，the low-，medium-，and high-dose groups were given

Shaoyao Decoction

by gavage at doses of 7.74，15.47，and 30.94 g/（kg·d），respectively. The normal and model groups received equal volumes of saline by gavage daily at 8：00 a.m. for 7 consecutive days. The disease activity index （DAI） was recorded. On day 10，all mice were euthanized. Blood was collected via eyeball extraction，and colon segments from the anus to the end of the cecum were isolated and measured for length. Colon tissue pathology was observed by hematoxylin-eosin （HE） staining for histological inflammation scoring. Serum levels of IL-6，IL-1β，and TNF-α were measured by ELISA. Alcian blue-periodic acid-Schiff （AB-PAS） staining assessed goblet cells. The mRNA expression of Notch-1 and Hes-1 in colon tissue was measured by qPCR. Protein expression of Notch-1，Hes-1，and ATOH-1 was detected by Western blot. Mucin 2 （MUC2） protein expression was assessed by immunohistochemistry，and olfactomedin 4 （OLFM4） protein expression was observed by immunofluorescence.

Results

2

From day 2 of modeling，DAI scores increased gradually in all groups except the normal group，and the model group showed significantly higher DAI scores than the normal group （

P

<

0.01），peaking at day 10. On day 10，the medium- and high-dose

Shaoyao Decoction

gr

oups had significantly lower DAI scores than the model group （

P

<

0.05，

P

<

0.01）. Colon length was shorter in the model group than the normal group （

P

<

0.01），and longer in the low-，medium-，and high-dose groups compared with the model group （

P

<

0.05）. Histopathological analysis showed marked improvement in the

Shaoyao Decoction

groups compared with the model group，with normal and uniform intestinal thickness，occasional irregular villi and lamina propria morphology，and normal cell size and density. Inflammation scores in medium- and high-dose groups were significantly lower than those in the model group （

P

<

0.01）. Serum IL-6，IL-1β，and TNF-α levels were significantly higher in the model group than in the normal group （

P

<

0.01），but significantly lower in all

Shaoyao Decoction

groups compared with the model group （

P

<

0.05，

P

<

0.01）. The number of goblet cells in colon tissue was reduced in the model group compared with the normal group，but increased in all

Shaoyao Decoction

groups compared with the model group. Notch-1 and Hes-1 mRNA expression was significantly higher in the model group than in the normal group （

P

<

0.05，

P

<

0.01），whereas medium- and high-dose groups showed significant decreases compared with the model group （

P

<

0.05，

P

<

0.01）. Notch-1 and Hes-1 protein expression in the model group was higher （

P

<

0.01），and ATOH-1 protein expression was lower than in the normal group （

P

<

0.01）. Compared with the results in the model group，Notch-1 protein expression was lower in the medium- and high-dose groups （

P

<

0.05），Hes-1 protein expression was lower in low- and high-dose groups （

P

<

0.05），and ATOH-1 protein expression was higher in all

Shaoyao Decoction

groups （

P

<

0.01）. MUC2 protein expression optical density was lower in the model group than in the normal group （

P

<

0.01），but higher in the medium- and high-dose groups compared with the model group （

P

<

0.05）. OLFM4 protein expression was elevated in the model group compared with the normal group and significantly reduced in all

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groups compared with the model group.

Conclusions

2

Shaoyao Decoction

significantly reduces intestinal inflammation and improves mucosal barrier function in DSS-induced UC mice. Its therapeutic effect is related to modulation of the Notch signaling pathway.