[Expression of the hepatic insulin signal transduction proteins in the rats with intrauterine growth retardation during the perinatal period].

Objective: To investigate the effects of maternal malnutrition on the expression of the insulin signal transduction proteins in the liver of perinatal rats.
Methods: (1) The dams were semi-starvation from the first day during pregnancy to build the animal model of intrauterine growth retardation (IUGR). On days 15, 17, 19, 21(E15, E17, E19, E21) of gestation, the fetuses were delivered by cesarean section. The fetal rats, placenta, fetal liver and the fetal brain were weighed respectively. And the placenta weight to the body weight ratio (PWR), the liver weight to the body weight ratio (LWR), the brain weight to the body weight ratio (BWR) were calculated; The expressions of the hepatic insulin receptor (IR), insulin receptor substrate-1 (IRS-1), insulin receptor subtrate-2 (IRS-2), phosphatidyl inositol 3-kinse (PI3K) mRNA in the rats during perinatal period were detected by RT-PCR.
Results: (1) The PWR of the IUGR fetus on E15 was lower than that in the control (P < 0.05) and beyond E17 it was gradually higher than that in the control (P < 0.05). There were no differences of the mean values of LWR between the IUGR fetus and the control. On E17 the LWR of the IUGR fetus were slowly increased (P < 0.05). The average level of BWR of the IUGR fetus during the perinatal period was significant higher (P < 0.05). (2) The expressions of hepatic IRS-1 mRNA of the IUGR fetus were similar on E15 and E17, and lower than that in the control on E19 until P1 (P < 0.05); The contents of hepatic IRS-2 mRNA of the IUGR fetus were significantly lower on E15 until P1 than that of the control(P < 0.05); There were no differences of the expressions of fetal hepatic IR mRNA and fetal hepatic PI3K mRNA between the IUGR fetus and the control(P > 0.05).
Conclusion: (1) In order to protect the development of brain, the fetus that suffered maternal malnutrition throughout the pregnancy had liver weight and body weight reduced much more than brain weight, which was known as "brain spare effects". (2) The expressions of hepatic IR mRNA and PI3K mRNA of the fetus were in normal ranges; But the expressions of the hepatic IRS-1 mRNA and IRS-2 mRNA of the IUGR fetus were decreased during the perinatal period. These may be related to the growth retardation and insulin resistance of the adult IUGR rats.