Effects of pregnancy on insulin receptor in liver, skeletal muscle and adipose tissue of rats

Abstract

The mechanism responsible for insulin resistance during pregnancy remains unclear. Considerable evidence indicates that the insulin receptor plays an important role in insulin sensitivity. It seems possiblethat the hormonal milieu during gestation could have an effect on the insulin receptor. In the present study, measurements of tyrosine phosphorylation and protein content of the insulin receptor and expressionof its gene in liver, skeletal muscle and adipose tissue indicate that during pregnancy significant changes occur in these parameters. We found that at the end of early gestation (day 10), muscle and adiposetissue are very sensitive to insulin action because the amount, phosphorylation and gene expression of insulin receptor is higher than in late gestation (days 15–20), while the tissue which is mostsensitive to insulin action in late gestation is the liver. Our hypothesis is that these results are connected with changes in the concentrations of estradiol and progesterone observed during pregnancy.In conclusion, our previous and present findings seem to demonstrate that the different concentrations of gestational hormones play an important role in insulin sensitivity in this period and that eachtissue responds in the most appropriate manner to guarantee the gestation in its entirety.