Objective To explore the effect of maternal intervention of Zuogui Pills（左归丸） on the offspring of rats with a model of gestational diabetes mellitus（GDM） and the mechanism. Methods Female rats were caged with male rats for pregnancy. Ninety pregnant rats were obtained and randomly divided into normal group

model group

insulin aspart group

and Zuogui Pills low

medium and high dose groups

with 15 rats in each group. The intraperitoneal injection of streptozotocin was used to establish a GDM model in pregnant rats of all groups except for normal group. After modeling

Zuogui Pills was administered by gavage in low

medium and high dose groups at a dosage of 2.5

5.0 and 10.0 g/（kg·d）

respectively. In normal group and model group

10 ml/（kg·d） normal saline was given by gavage

while in the insulin aspart group

the subcutaneous injection of 20 U/（kg·d） insulin aspart was administered. All the interventions were given once daily

for 14 days. Western blotting was used to detect the protein expression of pancreatic and duodenal homeobox-1（PDX-1） of the fetal rats. Real-time PCR method and bisulfite sequencing PCR（BSP） method were used to detect mRNA expression and gene methylation expression of hepatocyte nuclear factor-6（HNF-6）

respectively. Results Compared to normal group

the model group had lower expression levels of PDX-1 protein

HNF-6 mRNA and its methylation（P<0.05）. Compared to model group

the PDX-1 protein expression significantly increased in insulin aspart group and all Zuogui Pills groups; the HNF-6 mRNA expression and its methylation significantly increased in Zuogui Pills groups

while decreased in insulin aspart group（P<0.05）. Compared to insulin aspart group

Zuogui Pills medium dose group had higher expression of PDX-1 protein

and all Zuogui Pills groups had higher HNF-6 mRNA and methylation expression（P<0.05）. Compared among Zuogui Pills groups

the expression of PDX-1 protein

HNF-6 mRNA and its methylation in the medium dose group were the highest（P<0.05）. The expression of HNF-6 mRNA and methylation in the high dose group were significantly higher than in low dose group（P<0.05）. The expression of HNF-6 mRNA was positively correlated with its methylation（P<0.05

r=0.779）. Conclusion Zuogui Pills can up-regulate the methylation level of HNF-6 to enhance its mRNA expression and further up-regulating the protein expression of PDX-1

thereby regulating the pancreas development of fetal rats and reducing the incidence of related diseases.