[Effects of L-Arg on expression of PI3K and PKB in liver among low-birth-weight newborn rats].

Objective: To measure the expression of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB) in liver tissue among low-birth-weight newborn rats treated with L-arginine (L-Arg) in early life, and to investigate the effect of L-Arg on insulin resistance.

Methods: Eighteen pregnant rats were randomly divided into three groups: control, model and intervention (n=6 each). The control group was fed with normal protein feed (protein content=21%) during pregnancy to establish a normal-birth-weight newborn rat model, and the model and intervention groups were fed with low-protein feed (protein content=10%) during pregnancy to establish a low-birth-weight newborn rat model. Newborn rats from the three pregnant rat groups were also assigned to control, model and intervention groups. During 21 days of lactation, maternal rats in the control and model groups were fed with normal protein feed and normal drinking water, while maternal rats in the intervention group were fed with normal protein feed and drinking water rich in L-Arg (200 mg/kg·d). After ablactation, the three groups of newborn rats were fed with normal protein feed and normal drinking water. Liver tissue samples were collected from these newborn rats at 1, 3 and 8 weeks after birth. Protein expression of PI3K and PKB in liver tissue was measured by Western blot.

Results: At 1 week after birth, the newborn rats in the intervention group had significantly higher protein expression of PI3K than in the model group (P=0.045), but there was no significant difference when compared with the control group (P=0.503). At 8 weeks after birth, the newborn rats in the intervention group had significantly higher protein expression of PKB than the model group (P=0.039), but there was no significant difference when compared with the control group (P>0.05).

Conclusions: A supplement of L-Arg in early life can boost protein synthesis, increase protein expression of PI3K and PKB in liver tissue, promote insulin signaling and reduce insulin resistance.