Study on changes of pancreatic Pdx-1 gene epigenetic mechanism of offspring rats with chronic intrauterine hypoxia

Abstract

Objective To study the pancreatic expression level of Pdx-1 gene of the offspring rats after SD pregnant rats suffering from chronic intrauterine hypoxia (CIH). Methods A total of 16 healthy SD pregnant rats were chosen as research objects, and they were randomly divided into CIH group and control group by random digits table, and 8 pregnant rats of each group. The SD pregnant rats in CIH group were established as CIH pregnant rats model, while the SD pregnant rats in control group did not receive any hypoxia treatment. After 1 h of hypoxia treatment on the first day of CIH group, arterial blood gas analysis was performed on two groups of SD pregnant rats. SD pregnant rats in CIH group and control group delivered 192 and 208 offspring rats, respectively. When the offspring rats of two groups were 56 days of age, random number table method was used to select 24 offspring rats in each group. Then they were killed and pancreases were obtained from them, and enrolled into CIH sub-group and control sub-group. Hematoxylin-eosin (HE) stain and light microscope were used to observe the changes of pancreatic islet of the offspring rats in CIH sub-group and control sub-group (6 offspring rats in each sub-group), and Image Pro Plus 6.0 image analysis software was used for quantitative analysis of the islet beta cells area. Immunohistochemical method and Western blotting method were used to detect the pancreatic Pdx-1 protein expression level of the offspring rats in two sub-groups (6 offspring rats in each sub-group). Bisulfite genomic sequencing method was used to detect the promoter methylation of pancreatic Pdx-1 gene of the offspring rats in two sub-groups (6 offspring rats in each sub-group). The arterial blood gas analysis results of SD pregnant rats in CIH group and control group, the islet beta cells area, relative integral optical density (IOD) value and expression level of pancreatic Pdx-1 protein, and promoter methylation level of pancreatic Pdx-1 gene of the offspring rats in two sub-groups were statistically analyzed by statistical methods. Results ①The results of arterial blood gas analysis of SD pregnant rats in CIH group and control group showed that the saturation of oxygen in artery (SaO2), partial pressure of oxygen in artery (PaO2) levels in CIH group were significantly decreased compared with those in control group, and both the differences were statistically significant (t=9.345, P 0.05). Conclusions SD pregnant rats suffer CIH during pregnancy can lead to the increase of methylation of pancreatic Pdx-1 gene promoter and the decrease of pancreatic Pdx-1 gene expression and the decrease of pancreatic Pdx-1 protein expression of the offspring rats. Key words: Chronic intermittent hypoxia; Pancreas; Pdx-1 gene, rat; Rats, Sprague-Dawley; Methylation