The effect of high-glucose-high-fat diet in male SD rats on methylation of INSR gene in F1 offspring

Abstract

Objective To study the effect of high-glucose-high-fat diet on expression and methylation of insulin receptor(INSR)gene in F1 offspring. Methods Sixty 5-week-old male SD rats were randomly divided into two groups: normal diet group and high-glucose-high-fat diet group. After rats were fed for three months, all male rats were performed to copulate with normal female rats. The body weight, blood glucose, and blood insulin of neonatal rats of F1 offspring were measured. The genome DNA, total RNA, and total protein were extracted from livers, brains, and muscles of neonatal rats. Relative expression of INSR in both mRNA level and protein level were detected using a realtime PCR test and a Western blot test respectively. Methylation of INSR promoter was analyzed by a methylation specific PCR(MSP). Results Both body weight and fasting glucose were without significant difference in two groups. In high-glucose-high-fat diet group, both the glucose tolerance and insulin tolerance of neonatal rats in F1 offspring were significantly decreased. Except that in brains, the expressions of INSR gene in livers and in muscles of neonatal rats in high-glucose-high-fat diet group were down-regulated in mRNA(realtime PCR)and protein levels(Western blot)compared to the normal diet group. Meanwhile, the methylation of INSR gene in livers and muscles were strengthened in high-glucose-high-fat diet group. Conclusion A high-glucose-high-fat diet fed to male SD rats leads to the decrease in glucose tolerance, insulin tolerance, and the inhibition of expression of hepatic and muscle INSR gene in neonatal offspring. The methylation of INSR gene could be involved in this phenomenon. (Chin J Endocrinol Metab, 2016, 32: 1010-1014) Key words: Methylation; Insulin receptor gene; F1 offspring; High-glucose-high-fat diet; Male; Sprague Dawley rats