Effect of maternal limb ischemic preconditioning on expression of caspase-3 in neurons in brain tissues after reoxygenation in fetal rats with intrauterine distress

Abstract

Objective To investigate the effect of maternal limb ischemic preconditioning on the expression of caspase-3 in neurons in brain tissues after reoxygenation in the fetal rats with intrauterine distress. Methods Forty Sprague-Dawley rats at 19 days of gestation were randomly divided into 4 groups (n=10 each) using a random number table: sham operation group (group S), limb ischemic preconditioning group (group LIP), fetal rat distress group (group FD), and limb ischemic preconditioning+ fetal rat distress group (group LIP+ FD). Distress/reoxygenation model was established by clamping the uterine and ovarian arteries and veins with a micro-artery clamp for 15 min followed by removal of the clamp to permit reperfusion.Limb ischemic preconditioning was induced by 3 cycles of occlusion of the lower limb blood flow at the site of the right groin for 5 min with a tourniquet followed by 5 min unclamping.In group LIP+ FD, the uterine and ovarian arteries and veins were clamped, and limb ischemic preconditioning was performed at the same time.Cesarean section was performed on 2 days after the end of treatments in each group, and the fetal rat mortality rate was calculated.The fetal rats alive were sacrificed, and the hippocampi were isolated for determination of neuronal apoptosis(by TUNEL) and expression of caspase-3 protein and mRNA (by Western blot and real-time reverse transcriptase polymerase chain reaction, respectively) in hippocampal CA1 region.Apoptosis index was calculated. Results Compared with group S, the fetal rat mortality rate and apoptosis index were significantly increased, and the expression of caspase-3 protein and mRNA in hippocampal CA1 region was significantly up-regulated in FD and LIP+ FD groups(P 0.05). Compared with group FD, the fetal rat mortality rate and apoptosis index were significantly decreased, and the expression of caspase-3 protein and mRNA in hippocampal CA1 region was significantly down-regulated in group LIP+ FD (P<0.05 or 0.01). Conclusion The mechanism by which maternal limb ischemic preconditioning inhibits apoptosis in neurons after reoxygenation is related to down-regulation of the expression of caspase-3 in the fetal rats with intrauterine distress. Key words: Extremities; Ischemic preconditioning; Caspase 3; Fetal distress; Reperfusion injury; Brain