Pancreatic beta-cell Function and Development in Male Offspring of Protein-Malnourished Rats

Park, Hyeong Kyu; Jin, Cheng Ji; Park, Do Joon; Shin, Chan Soo; Park, Kyong Soo; Kim, Seong Yeon; Lee, Hong Kyu

Abstract

BACKGROUND: Nutritional deprivation of the fetus and infant may be associated with susceptibility to impaired glucose tolerance or type 2 diabetes in adult life. This association has been interpreted as a long-term effects of nutritional factors that reduce fetal growth and impair the development of tissues that regulate glucose metabolism. This study aimed to investigate the effect of protein malnutrition in a fetus and early life on the pancreatic beta-cell function and development.
METHODS
Sprague-Dawley rats were fed a low-protein (8% casein) diet during pregnancy and lactation. Their male offspring were weaned onto either a control (18% casein) diet (recuperated group, R) or a low-protein diet (low-protein group, LP). The offspring of the rats fed control diet were weaned onto control diet (control group, C). Glucose tolerance tests and morphometry of the pancreas were performed to evaluate the pancreatic beta-cell function and development at the 25th week of age.
RESULTS
Offspring of the protein-malnourished rats had a significantly lower body weights than the controls. The R and LP showed no major impairment in glucose tolerance, but the plasma insulin concentrations in the R (0.24+/-.03 nmol/L) and LP (0.28+/-.02 nmol/L) groups were lower at 20 min during IVGTT than the C (0.43+/-.05 nmol/L) groups. The areas under the curve for insulin (AUC insulin) during IVGTT were significantly lower in R and LP (0.39+/-.03 nmol/L/min, 0.43+/-.02 nmol/L/min) groups than the C (0.54+/-.03 nmol/L/min) group. In particular, the rats with fetal protein malnutrition showed severe impairment in late-phase insulin secretion to a glucose load. Both the pancreas weight and the proportion of the pancreas weight to the body weight were significantly lower in the R and LP groups than the C group. The proportion of beta-cells to pancreatic cells was lower in the LP (0.91+/-.14%) group than the C (2.19+/-.23%) and R (1.79+/-.25%) group. The relative beta-cell mass was significantly lower in the LP (by 62%) group that the C group.
CONCLUSION
Rats with fetal protein malnutrition showed persistently impaired pancreatic beta-cell development and reduced insulin secretion capacity. These findings suggest that in utero protein malnutrition can contribute to the development of type 2 diabetes in adult life along with other deleterious environmental or genetic conditions.