Objective To investigate the effect of theanine pretreatment on DNA repair function in neurons during brain ischemia-reperfusion (I/R) injury in rats.Methods One hundred and eight male Sprague-Dawley rats,weighing 290-310 g,aged 15 weeks,were randomly divided into 3 groups (n =36 each) using a random number table:sham operation group (S group),I/R group and theanine pretreatment group (T group).Global cerebral I/R was produced by 4-vessel occlusion method.Bilateral vertebral arteries were electrically cauterized,and bilateral common carotid arteries were clamped for 6 min.Theanine 1 g/kg was injected intravenously at 4 h before clamping bilateral common carotid arteries in T group,and the equal volume of normal saline was given in the other two groups.At 2,6,12,24,48 and 72 h of reperfusion,6 rats were selected in each group and sacrificed,the brains were removed,and the hippocampus was isolated for determination of the number of viable neurons in the hippocampal CA1 region (with a light microscope),apoptosis in neurons in the hippocampal CA1 region (by TUNEL),and expression of DNA repair protein X-ray repair cross-complementing group 1 (XRCC1) and Ku70 (by immunohistochemistry).The apoptotic index was calculated.Results Compared with S group,the number of viable neurons was significantly decreased,and the apoptotic index was significantly increased at 6,12,24,48 and 72 h of reperfusion,and the expression of XRCC1 and Ku70 was significantly down-regulated at 2,6,12,24,48 and 72 h of reperfusion in I/R group (P＜0.01).Compared with I/R group,the number of viable neurons was significantly increased at 12,24,48 and 72 h of reperfusion,the apoptotic index was significantly decreased at 6,12,24,48 and 72 h of reperfusion,and the expression of XRCC1 and Ku70 was significantly up-regulated at 2,6,12,24,48 and 72 h of reperfusion in T group (P ＜ 0.01).Conclusion The mechanism by which theanine pretreatment attenuates brain I/R injury is related to enhancement of DNA repair function and reduction of neuronal apoptosis in rats.

Objective: To observe the expression changes of Notch and nuclear factor-κB (NF-κB) signaling pathways in rat myocardium post myocardial infarction. Methods: Myocardial infarction was established by ligation of the left anterior descending coronary artery(MI group), sham rats (similar surgical procedure without coronary artery ligation) served as control, the rats were sacrificed at first week, 4th and 8th week after operation, the non-infarct myocardial tissue in both groups was obtained to detect the mRNA expression of Notch1, Dll4 and Hes1 by RT-PCR, the protein expression of NICD1 was detected by Western blot, the nuclear protein p65 content was detected to reflect the activation degree of NF-κB signaling in the cardiomyocytes. Results: The myocardial mRNA expression of Notch1 in MI group was significantly higher than in control group (1.68±0.35 vs. 0.47±0.12, P<0.05) at first week, and tended to be higher at the 4th week and 8th week (P>0.05). The mRNA expression of Dll4 and Hes1 was similar between the two groups at the three time points. NICD1 protein level was increased at the first week in MI group as compared with control group (1.31±0.33 vs.0.45±0.11, P<0.05), which tended also to be higher at the 4th week and 8th week post operation (P>0.05). For NF-κB activation study, the nuclear protein p65 content was higher at first week, 4th week and 8th week in MI group as compared with respective control groups (0.286±0.052 vs.0.049±0.016 (P<0.01), 0.247±0.056 vs. 0.043±0.018 (P<0.01), 0.120±0.033 vs. 0.044±0.009 (P<0.05)), the most significant increase was found in the first week. Conclusions Notch and NF-κB signaling pathways are actively involved in the process of ventricular remodeling after myocardial infarction. Notch1 and NF-κB signaling pathways are both activated at the first week after myocardial infarction, NF-κB signaling pathway activation after myocardial infarction continues up to 8 weeks. These two signal transduction pathways may thus serve as new targets for future intervention studies to prevent heart failure.