The administration of a low protein (LP, 8% protein/dry matter) but isocaloric diet to gestating rats did not affect their fertility, but slightly reduced the quantity of food intake as well as body weight gain. The LP diet also did not affect the placental weight, but the weight of the offspring was decreased. Accordingly the fetal endocrine pancreas was altered by the LP diet. Two different morphometric analyses showed that in the LP neonate B-cell proliferation and islet size were reduced in the head of the pancreas. In the pancreatic tail, these parameters were also decreased but to a lesser extend. Islet vascularization in the neonates was dramatically reduced in both parts of the pancreas when the mothers were fed with the LP diet.

A low-protein diet (8 vs. 20%) administered during pregnancy affects the structure and function of the endocrine pancreas of the offspring. At 21.5 days of gestation, we reported a reduction of cell proliferation, islet size, islet vascularization, and pancreatic insulin content. In this study, we demonstrated an impairment of insulin secretion of these fetal islets when stimulated in vitro with amino acids such as arginine and leucine. If the offspring is kept on the same low-protein diet during suckling, weaning, and adulthood, fasting insulin levels remain low in the presence of normal blood glucose levels. Glucose tolerance at 70 days is impaired, with lower insulin response. In addition, permanent functional damage seems to be induced in utero by a low-protein diet, because a normal diet given from birth to adulthood does not restore normal insulin response after a glucose challenge. Our experimental results stress the impact of a balanced diet with qualitative and quantitative amino acid composition for the fetal endocrine pancreas to develop normally, without lasting functional and structural consequences in adulthood.