Effects Of Full-term Pregnant Rats Limb Ischemic Preconditioning On The PI3K/AKT/GSK-3β Signaling Pathways In The Fetal Hippocampal Neurons Induced By Distress-reoxygenation

Object: To investigate the effects of full-term pregnant rats limb ischemic preconditioning on the phosphoinositide 3 kinase/protein kinase B and glycogen synthase kinase 3β(PI3K/AKT/GSK-3β) signaling pathways in the fetal hippocampal neurons undergone distress-reoxygenation in female rats. To explor the way to reduce brain damage of intrauterine distress and its long-term sequelae, providing a theoretical basis and new idea for the clinical application.Methods: SD(the Sprague Dawley) rats lived in cages with one male and three females to culture pregnant rats.The pregnant SD rats were intraperitoneal anaesthetized on embryonic Day 20.Intrauterine distress model was installed by blocking the arteriovenous of the uterine and ovarian by micro artery clips for 15 min followed by releasing the clips to recover reperfusion; the model of LIP were established by 5 min occlusion followed with the same period of reperfusion on the right hind femoral artery, and repeated for three cycles. The pregnancy rats were randomly divided into five groups(n=6), Sham(S) group, Control(LIP) group, Fetal distress(FD)group, LIP plus intrauterine distress(LIP+FD) group and P13 K inhibitor LY294002 group(LY294002). Cesarean section occurred in pregnant rats(21 days gestation) to acquire live pups in each group after 24 hours. The fetuses were decapitated and the pyramidal cells in hippocampal CA1 region were measured through light microscope with HE staining. Neural apoptosis was detected by terminal deoxynucleotidyl transferase-mediated d UTP-biotin nick end labeling(TUNEL) staining. The expressionof total AKT and total GSK-3β and phosphorylation of AKT and GSK-3β in hippocampal CA1 region of fetal rats were determined by Western blotting test. Inhibitor content was measured by High Performance Liquid Chromatography( HPLC).Result: Compared with group S, damages of hippocampal CA1 region in fetuses were heavier, the rates of neural apoptosis increased, and phosphorylated AKT, phosphorylated GSK-3β expression decreased(P < 0.05) in group FD, while with no significant differences of groups LIP( P>0.05). Compared with group FD, damages of hippocampal CA1 region were reduced, the rates of neural apoptosis were decreased(P < 0.05), phosphorylated AKT, phosphorylated GSK-3 expression were increased(P < 0.05) in group FD+LIP. Compared with group FD+LIP, damages of hippocampal CA1 region and the rates of neural apoptosis were increased(P < 0.05), phosphorylated AKT, phosphorylated GSK-3 expression significantly were decreased(P < 0.05) in group LY294002. There were no significant differences in the expression of AKT and GSK-3 in each group(P both > 0.05).Conclusions: The rates of apoptosis and neuronal damages were increased,and the phosphorylated AKT and phosphorylated GSK-3β expression were decreased in the hippocampal CA1 region in fetuses undergone distress-reoxygenation in female rats.Limb ischemic preconditioning could reduce the rates of apoptosis and neuronal damages, which maybe associated with increased phosphorylation of AKT and phosphorylated GSK-3β expression through activating PI3 K / AKT / GSK-3β signaling pathway to protect the brain.