关键词: 宫内生长受限, 胰岛素抵抗, 叶酸, 维生素B12, PI3K

Abstract: Objective To investigate the influence of adding folic acid and vitamin B12 in maternal lactation on the expression of phosphatidylinositol 3-kinase(PI3K)in phosphatidyl inositol 3-kinse /protein kinase B (PI3K/AKT) insulin signaling pathway,and to analyze the relationship between the changes in the expression of the main molecules and the change in insulin resistance. Methods 1)To establish the model of insulin resistance index (IUGR) rats by low-protein (LP) and caloric restriction in the second and third trimester of pregnancy.IUGR newborn pups were randomly divided into IUGR intervention group and IUGR without intervention group.Lactating female rats of the intervention group were fed with high folate and vitamin B12 in the diet; Lactating female rats of without intervention group were fed normal diet.All of newborn pups were weaned at the 21st day after birth and then fed with normal diet to 120 days.2)On the 21st,60th and 120th day after birth,fasting plasma glucose (FPG) and fasting insulin (FINS) of the three groups were tested.IRI were calculated to evaluate insulin sensitivity.3)On the 21st,60th and 120th day after birth,skeletal muscle tissues were collected from rats of the three groups,phosphatidylinositol 3-kinase(PI3K) gene and protein expression levels were determined by using quantitative RT-PCR and western blotting. Results 1)Birth weights of LP offspring[(4.44±0.58)g] were significantly lower than those of NP ones[(7.03±0.56)g] (t=15.75,P<0.05).The incidence of IUGR in LP was 93.33%.2)On the 21st day after birth,FPG,FINS and IRI of the three groups showed no significant difference.On the 60th and the 120th day,FPG,FINS and IRI of IUGR in the intervention group were significantly lower than those of IUGR in non-intervention group,but were higher than those of the control group (all P <0.05).3)On the 21st,60th and 120th day,the levels of PI3K mRNA and protein expression were highest in the NP group and were lowest in IUGR without intervention group.They appeared significant difference in three groups(all P<0.05).4)On the 60th and 120th day,both IRI levels of IUGR without intervention group and the intervention group had a negative correlation with PI3K (both P<0.05). Conclusion Adding folic acid and vitamin B12 in maternal lactation has an impact on the expression of PI3K in IUGR rats,and these changes are closely correlated with insulin resistance.

Key words: intrauterine growth retardation, insulin resistance, folic acid, vitamin B12, PI3K