RESUMO
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 or 0.0l),and no significant change was found in the parameters mentioned above in group LIP (P＞0.05).Compared with group FD,the fetal rat mortality rate and apoptosis index were significantly decreascd,and the expression of caspase-3 protein and mRNA iu 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.
RESUMO
[ ABSTRACT] AIM:To investigate the effects of maternal limb ischemic preconditioning ( LIP) on the mitochon-drial structures and functions of the hippocampal neurons induced by reoxygenation in the intrauterine distress fetal rats. METHODS:Pregnant rats (n=40) were randomly divided into 4 groups: sham (S) group, LIP group, fetal distress ( FD) group and LIP+FD group.Intrauterine ischemia model was established through the experimental design.The ultra-structure of the mitochondria in CA1 area of the hippocampus was observed .The mitochondrial membrane potential and re-active oxygen species ( ROS) were measured .The content of ATP and MDA in the hippocampus tissue was detected.The activity of Mn-SOD was observed.RESULTS:Compared with sham group, the ultrastructure of mitochondria in CA1 area of the hippocampus was damaged in FD group and LIP+FD group.The mitochondrial membrane potential, the content of ATP and the activity of Mn-SOD were decreased.However, the content of ROS and MDA was increased.Compared with FD group, the ultrastructure of mitochondria in CA1 area of the hippocampus was intact in LIP+FD group.Furthermore, the reduced mitochondrial membrane potential and ATP content were inhibited.The activity of Mn-SOD was increased, but the content of ROS and MDA was decreased in LIP+FD group.CONCLUSION:Limb ischemia preconditioning inhibits the damage the mitochondria of fetal hippocampal neurons induced by reoxygenation in the intrauterine distress fetal rats.