| ObjectivesCardiac arrest (CA) induced by various reasons leads to severe systemic organ ischemia and hypoxia. A timely implement of cardiopulmonary resuscitation (CPR) on sufferers is an essential rescue for the restoration of spontaneous circulation (ROSC). But cerebral ischemia injure following to CPR severely threatens human health. The mechanisms underlying brain injury included the reactive oxygen species (ROS) injury, excitotoxicity, calcium overload, apoptosis. Among many pathological causes, excessive ROS produced in ischemia reperfusion is a major factor. So how to reduce ROS generation to alleviate brain injury in CPR is a hotspot in emergency medicine.ROS reduction could lessen postresuscitation brain injury, by being against oxidative stress damage, and ROS could be used as a biological signal.through activating MAPK signaling pathways which generate a large number of ROS and futher lead to brain damage. Our previous studies have confirmed that the antioxidant tea polyphenols (TP) have antioxidant properties, besides, could also by influencing the MAPK signaling pathways play a protective effect on brain tissue. The results for ROS generation increase and the activation of C-jun N-terminal kinase (JNK) signaling pathway, have brought an obvious damage to the brain, and the use of TP and JNK signaling pathway inhibitor could reduce the ROS, Malondialdehyde (MDA) levels and increasing superoxide dismutase(SOD) activity to alleviate hippocampal neuron damage, thus, all which could improve the survival time and long-term survival rate. On the basis of previous studies, our group focused on another signaling pathway of the MAPK family,extracellular signal regulating kinase (ERK) signaling pathway to explore whether ERK signaling pathways inhibitor could also reduce the ROS, MDA levels and increase SOD activity, whether ERK signaling pathway inhibitor and TP's combination could improve the protective function of TP on brain tissue.MethodOne hundred and sixty-eight Sprague-Dawley rats after ROSC were randomly divided into sham (SH) group, ischemia reperfusion (IR) group, TP group, ERK signaling pathway inhibitor PD98059 (PD) group and TP4+PD group. All groups induced CA through transesophageal alternating current stimulation method except SH group. Five minutes of cardiac arrest later, CPR was performed. Then TP (10mg/kg), PD (0.3mg/kg), TP+PD, saltine was correctly administrated by intra-vein immediately. ROS, MDA and SOD in brain tissue were detected and neurological deficit scores were assessed at 12, 24, 48 and 72 hours after ROSC. The survival time and accumulate survival rate were observed until 72 h after ROSC.Results1. Survival time All rats in the SH group lived to the end point of 72 hour.Longer survival time was seen in the TP, PD and TP+PD groups compared with the IR group (26.38 ± 25.40 vs 52.08 ± 14.34, 52.25 ± 19.09, 60.08 ± 19.60, P <0.05). Longer survival time was seen in the TP+PD groups compared with TP and PD groups. There were no significant differences among the TP, PD and TP+PD groups (P>0.05).2. Accumulate survival rate All rats in the SH group have 100% of the accumulate survival rate. Better accumulate survival rates were observed at 12 and 24 hours after ROSC in TP and PD group than in the IR group (P <0.05),but there were no significant differences at 48 and 72 hour (P >0.05). Better accumulate survival rates were observed at 12, 24, 48 and 72 hours after ROSC in TP+PD than in the IR group (P <0.05). Compared with TP group, the accumulate survival rate of TP+PD group significantly increased at 72 hour (P<0.05). There were no significant differences between the PD and TP +PD groups at 72 hour (P>0.05).3. Neurological deficit scores The neurological deficit scores (NDS) of SH group rats were 80 points at 12h, 24h, 48h and 72 hours. Deficits were consistently lessened in rates that had been treated with TP, PD and PD+TP compared with those in the IR group at 12 hour (48.77 ± 6.74 vs 59.09: ± 7.20,62.23 ± 3.00, 63.08 ± 3.57,P <0.05),24 hour (54.86 ± 2.81 vs 65.60 ± 2.69,67.35 ± 4.17, 68.46 ± 3.54, P < 00-5),48 hour (59.25 ± 4.54 vs 70.99: ± 2.07,71.65 ± 2.35, 72.65 ± 2.36, P <0.05). There were no significant differences among the IR, TP, PD and PD+TP groups at 72 hour (P > 0.05). The NDS of TP+PD group at each time point were higher than that of TP and PD groups.There were no significant differences among theTP, PD and PD+TP groups(P>0.05).4. ROS levels Compared to SH group, the ROS levels increased markedly in rats treated with saline at 12, 24, 48 and 72 hours (421.49 ± 32.40 vs 767.80 ± 13.41,413.57 ± 37.46 vs 822.56 ±44.83, 415.33 ± 18.54 vs 721.17± 34.27, 390.95 ± 35.73 vs 615.67 ± 24.58, P <0.01) after ROSC in the IR group. Compared with IR group, ROS levels decreased significantly in the TP,PD and TP+PD groups at 12, 24, 48 and 72 hours (767.80±13.41 vs 582.17 ±13.41,371.70 ± 10.30, 367.87 ± 16.20; 822.56 ± 44.83 vs 648.74 ±56.23,387.80 ± 33.50, 384.78 ± 68.42; 721.17 ± 34.27 vs 534.07 ± 57.44, 383.31 ±22.18, 364.19±35.48; 615.67 ± 24.58 vs 458.72 ± 54.90, 375.85 ± 39.00,360.91 ± 21.88,P < 0.05 orP < 0.01). Compared with TP group, ROS levels decreased significantly in the PD and TP+PD groups (P<0.05). There were no significant differences between the PD and TP+PD groups. ROS reached a peak at 24 hour in the four treatment groups.5. MDA levels Compared with SH group, MAD levels increased markedly at 12, 24, 48, and 72 hours (4.67 ± 0.66 vs 7.47 ± 6.01,4.50 ± 0.60 vs8.38 ± 0.75, 4.90 ± 1.03 vs 10.19 ± 0.70,4.80 ± 0.66 vs 7.50 ± 7.29, P<0.05)after ROSC in the IR group. Compared with IR group, MAD levels decreased significantly in TP,PD and TP + PD groups at all time points (7.47 ± 6.01 vs 5.15 ± 0.75, 5.82 ± 0.80, 6.13 ± 1.10; 8.38 ± 0.75 vs 5.56 ± 1.10, 9.16 ± 0.63,8.68 ± 1.01; 10.19 ± 0.70 vs 6.41 ± 0.81,5.19 ± 0.62, 5.28 ± 0.46; 7.50 ± 7.29 vs 5.34 ± 6.22, 5.03 ± 0.71, 5.22 ± 0.61,P <0.01). Both the PD and PD+TP groups had higher MAD levels at 24 hour, however, lower at 48 hour than the TP group.6. SOD activity Compared with SH group, SOD activity decreased markedly at 12, 24, 48, and 72 hours (120.67 ± 8.96 vs 75.16 ± 4.85, 122.55±9.49 vs 61.65 ±8.56, 117.08 ± 12.10 vs 54.13 ±5.81, 118.40 ± 10.50 vs 60.67 q 7.17, P < 0.05) after ROSC in the IR group. Compared with IR group, SOD activity increased significantly in the TP, PD and PD+TP grops at all time points (75.16 ± 4.85 vs 101.28 ± 8.55, 97.33 ± 7.02, 92.78 ± 8.74; 61.65 ± 8.56 vs 91.41 ± 11.13, 70.60 ± 8.47, 79.39± 8.24; 54.13 ± 5.81 vs 82.71 ± 7.56,84.16 ± 6.75, 87.16 ± 6.75; 60.67 ± 7.17 vs 93.30 ± 7.61,83.24 ± 7.03, 91.36 ±12.83, P < 0.05). Both the PD and TP+PD groups had lower SOD activity at 24 hour, however, higher at 48 hour (P < 0.05) than the TP group.7. Histologic evaluation The dying neurons were stained by hematoxyl:in and eosin at 24h after ROSC, with swelling cell body, condensed nuclei, intense cytoplasmic eosinophilic staining, and disordered arrangement. A larger quantity of the dying neurons were seen in saline-treated rats than in those treated with TP, PD and TP+PD.ConclusionBoth TP and ERK signaling pathway inhibitor PD98059 with reducing ROS and MDA levels and elevating the vivo SOD activity, could reduce the hippocampus damage, improve neurological function and prolong the survival time after CA/CPR in rats. TP and PDs combination could enhance the oxidative stability of tea polyphenols in brain tissue. |
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