| Objective:This study is mainly to research the effects of sodium butyrate on pancreatic β-cell function in gestational diabetic mice and explore its mechanism of action.Methods:Part Ⅰ:One hundred and twenty female rats and 60 male rats were caged 2:1.Sperm was found on vaginal smear early the next morning and recorded as gestation day(GD0).52 rats were successfully conceived.The pregnant rats were randomly divided into four groups according to body weight: control group(group C),gestational diabetes mellitus group(group GDM),gestational diabetes mellitus + sodium butyrate group(group GB),and sodium butyrate group(group B),with 13 rats in each group.Groups C and B were injected intraperitoneally with citric acid-sodium citrate buffer on GD0.Groups GDM and GB were injected with 37 mg/kg of streptozotocin on GD0,and the increase in fasting blood glucose by 20% on pregnancy day 3 than before pregnancy was considered as successful model.Groups C and GDM drank normal water;Groups GB and B added200 mmol/L sodium butyrate to their drinking water from GD3.Groups GB and B added200mmol/L sodium butyrate in drinking water from day 3 of gestation.Body weight and water intake were measured every day,and fasting blood glucose was measured after overnight fasting for 12 h on the 2nd,5th,11 th,and 16 th days of pregnancy.The oral glucose tolerance test and insulin release test were was performed on gestation day 15.Part Ⅱ: Histopathological changes in the mouse pancreas were observed by hematoxylin-eosin staining.The effect of sodium butyrate on serum insulin,IL-1β,and IL-18 levels in GDM mice was detected by enzyme-linked immunosorbent assay.The effect of sodium butyrate on PPARγ,NLRP3,and caspase-1 protein expression in the pancreatic tissue of GDM mice was detected by Western blotting.Cells were divided into the control group(C group),high glucose group(HG group),high glucose + sodium butyrate group(HGB group),and sodium butyrate group(B group).Group C was incubated with glucose medium at 1g/L for 24 h.Group HG was incubated with medium containing different concentrations of glucose(2.5g/L,5g/L,7.5g/L,10g/L)for 24 h.Group B was incubated with medium containing different concentrations of sodium butyrate(0m M,2m M,4m M,6m M,8m M,10 m M)and incubated for 24 h.The optimal high sugar and sodium butyrate treatment concentrations were determined by tetrazolium salt assay.Then HGB group was incubated with 5g/L glucose + 4m M sodium butyrate and incubated for 24h;ELISA was used to detect the effect of sodium butyrate on βTC-6cells under high sugar environment.The effect of sodium butyrate on the expression of PPARγ,NLRP3,and caspase 1 protein in βTC-6 cells under high glucose environment was measured by Western blotting.Results:1.Sodium butyrate has good hypoglycemic effects: sodium butyrate can prevent excessive weight gain during pregnancy,reduce fasting blood glucose levels and improve the ability of GDM mice to clear glucose.2.The addition of 200 m M sodium butyrate in drinking water had no significant effect on the health of pregnant mice and the development of the fetal mice.3.The results of HE staining showed that compared with group C,a small amount of vacuolation of glandular cells was seen in the exocrine part of pancreatic tissue in the GDM group,a small number of small round vacuoles were seen in the cytoplasm,and more aqueous degeneration of glandular cells was seen in the GB group.Compared with the GDM group,there was no aqueous degeneration of glandular cells in the GB group.4.Sodium butyrate plays a hypoglycemic role by regulating PPARγ/NLRP3/caspase-1 signaling pathway in pancreatic beta cell.(1)ELISA results showed that sodium butyrate significantly increased insulin secretion(P = 0.002)and decreased serum IL-1β in GDM mice(F = 7.568,P = 0.006).(2)Western blotting results showed that sodium butyrate significantly up-regulated PPARγ in the pancreatic tissues of GDM mice.mice pancreatic tissue expression of PPARγ protein(P < 0.001)and down-regulated NLRP3(P= 0.005),caspase-1 protein(P = 0.008)expression in GDM mice pancreatic tissue.(3)The MTT results show that models can be successfully constructed for subsequent experimental studies at 5g/L glucose concentration.(4)ELISA results showed that sodium butyrate significantly increased insulin secretion of βTC-6 cells and decreased the levels of IL-1β,IL-18 in high glucose environment(all P < 0.05).(5)Western blotting results showed that sodium butyrate significantly up-regulated PPARγ protein expression and down-regulated NLRP3 and caspase-1 protein expression in βTC-6 cells in a high glucose environment(all P < 0.001).Conclusions:Sodium butyrate can effectively reduce blood glucose and IL-1β in GDM mice and improve their pancreatic histopathological lesions,and the mechanism may be related to the regulation of PPARγ/NLRP3/caspase-1 signaling pathway in pancreatic beta cell,which in turn increases insulin secretion levels. |
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