Objectives: To investigate the relationship between the birth weight of fetus and the P(70)S6K from ribosome in cells of placental tissues and investigate whether insulin can affect the P(70)S6K by the PI3K/AKT/mTOR (P(70)S6K) signaling pathway in the cells of the placental tissues and more regulate the birth weight of fetus.
Methods: (1) 60 cases of mature placental tissues after uterine-incision delivery without complications in the gestational period were selected as the investigated subjects, they were divided into three groups according to their birth weights. group 1. the weigh of the fetus > or = 4000 g, group 2. 3000 g < or = the weight of the fetus < 4000 g, group 3. the weight of the fetus < 3000 g, (2) 10 cases of mature placental tissues and 20 cases of villus in the early pregnant the fetus that were divided into insulin group, rapamycin group and control group according to stimulating factors. investigations on the insulin affection activities of P(70)S6K were carried out by immunoprecipitation, incorporation of [r-(32)P]ATP, tissue cell culture, Western blotting.
Results: (1) P(70)S6K activities in mature placental tissues (2546 +/- 357), (2333 +/- 318), (2111 +/- 315) cpm/mg, there were significant statistical differences in the comparison every two groups. (2) The P(70)S6K activities in the placenta from the insulin stimulation group was significantly elevated, the P(70)S6K activities in the placenta from the rapamycin stimulation group was significantly declined, there were statistical significance when each was compared with control group (P < 0.01). (3) P(70)S6K activities in the nutrient cells of earlier pregnant period and protein expression will be elevated under insulin stimulating. However, that would be declined under rapamycin stimulating, it was statistical significant when each group compared with the control group (P < 0.01).
Conclusion: The activities of P(70)S6K increased with the increase in the birth weight of the fetus, there was certain relationship between the activities of P(70)S6K in the placental tissues and the birth weight of the fetus and Insulin can regulate the activities of P(70)S6K in the placenta and earlier nutrient cells.