Effects Of Bisphenol A And Genistein On Glucose And Lipid Metabolism In Rats

Objective:(1) The effects of BPA and genistein treatment on glucose and lipid metabolism in male adult Wistar rats were observed.(2) To explore the possible mechanism of BPA exposre on disrupted blood glucose homeostasis of paternal rats, and observe the effects of long-term and "safe dose" of BPA exposure of paternal rats on birth outcome in their offspring, as well as glucose and lipid metabolism in adult offsprings.(3) To explore the effects and possible mechanisms of BPA and genistein treatment on hepatic lipid metabolism r in paternal rats.Methods:After acclimation for a week, male Wistar rats and weight between150-180g were were randomly divided into the following eight groups:the STD group, fed with standard chow diet (STD); the STD-BPA50group, fed with STD and BPA (50μg/kg); the STD-(BPA50+G) group, fed with STD, BPA (50μg/kg) and genistein (10mg/kg); the STD-G group, fed with STD and genistein (10mg/kg); the HFD group, fed with high-fat diet; the HFD-BPA50group, fed with high-fat diet and BPA (50μg/kg); the HFD-(BPA50+G) group, fed with high-fat diet, BPA (50μg/kg) and genistein (10mg/kg); the HFD-G group, fed with high-fat diet and genistein (10mg/kg). Before treatment and after21-week treatment, the serum glucose, insulin, total triglyceride and cholesterol were determined. The intraperitoneally glucose tolerance test (IPGTT) was operated at the end of30-week, and the rats were sacrificed after35-week treatment. The biochemical indicators were determined. After21-week treatment of male rats, rats in STD, STD-BPA50, HFD and HFD-BPA50groups were choosed as fathers, and mating with adult healthy female Wistar rats. Sex ratio, birth litter weight and number of per litter in offspring were calculated and recorded after birth. After weaning, offsprings were fed with STD and were sacrificed at the age of10-week old. The pancreatic β-cell aera was determined by immunofluorescence method. Real-time quantitative PCR was used to determine the mRNA expression levels of LC3, Beclin-1and Bip in pancreas. Immunohistochemisty and western blotting methods were used to determine the protein expression of LC3in pancreas. The laser confocal microscopy was used to determine the LC3protein expression in β-cells. The metabolism products of blood were determined. The HOMA-IR and insulin sencitivity were calculated. The hematoxylin and eosin stain was used to observe the hepatic pathology in paternal rats; Real-time quantitative PCR was used to detect the gene expression of key lipid metabolism in the liver. The western blot method was used to determine the expression of PPARa, PPARγ and LC3in liver.Results:(1) After35-week treatment, the blood glucose level in rats of HFD-BPA50group was higher than HFD group (P＜0.01). After35-week treatment, insulin level was higher in STD-BPA50group than STD group (P＜0.05) and STD-G group (P＜0.01). In IPGTT, the blood glucose of15min and30min time points and the aera under curve (AUC) in HFD-BPA50group were higher than HFD group (P＜0.05). Additionally, after35-week treatmet, the HOMA-IR in STD-BPA50was higher than that in STD group and STD-G group (P＜0.01), and the insulin sensitivity index in STD-BPA50was lower than in STD group (P＜0.05). The HOMA-IR index in HFD group was higher than HFD-(BPA50+G) group (P＜0.05) and HFD-G group (P＜0.01) after21-week treatment. After35-week treatment, the serum TG was lower in HFD-G group was lower than in HFD-BPA50group (P＜0.05); and the serum TC in HFD group and HFD-BPA50group were higher than HFD-G group (P＜0.05). Compared to HFD group, the TG and TC of liver in HFD-(BPA50+G) group and HFD-G group were significantly decreased.(2) After HFD and BPA treatment, the mass of pancreatic β-cells in paternal pancreas were markedly increased (P＜0.01). In addition, HFD and BPA treatment markedly increased the mRNA expression level of LC3, Beclin-1and Bip in paternal pancreas. Moreover, the protein expression of LC3was increased in HFD and BPA treated groups (P＜0.01). The protein of LC3expression in paternal pancreas P-cells was increased after HFD and BPA treatment. There were no significant differences of sex ratio, birth litter weight, number of per litter, blood glucose and lipid in four groups of offspring (P＜0.05).(3) The mRNA expression of SREBP-1C was increased in HFD group, HFD-(BPA50+G) group and HFD-G group (P＜0.05); the mRNA and protein expression of PPARy in liver of HFD group was higher than STD group, HFD-(BPA50+G) group and HFD-G group (P＜0.05); Moreover, the mRNA and protein expression of LC3in HFD group was lower than in STD group (P＜0.05).Conclusion:(1) Long-term BPA exposure induced insulin resistance and blood glucose intorlerance of rats, and genistein alleviated the lipid metabolic disorder of HFD-fed rats.(2) The disrupted function of pancreatic β-cells by BPA exposure in paternal rats may be related to upregulated endoplasmic reticulum stress and autophagy. Paternal rats exposed to long-term and "safe dose" of BPA did not affect birth outcome, as well as blood glucose and lipid metabolism of their offspring.(3) BPA treatment has no significant effect on the expression of lipid metabolic gene and LC3in liver of groups. Genistein may alleviate the hepatic lipid disorder through down-regulated PPARy expression in HFD-fed rats.