BACKGROUND: Recent studies have shown that the selective inhibitor of c-Jun N-terminal kinases(JNKs) signaling pathway, SP600125, exhibits neuronal protective effects in a rat model of brainischemia/reperfusion.OBJECTIVE: To determine the mechanisms of neuroprotective effects of SP600125 in a rat modelof brain ischemia/reperfusion, and determine the role of the JNK signaling pathway inSP600125-induced effects.DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at theAnimal Experiment Center, Medical School of Xi’an Jiaotong University from June 2007 toSeptember 2008.MATERIALS: SP600125 was provided by Biosource, USA; rabbit anti-phospho-JNK(Thr183/Tyr185) polyclonal antibody from Cell Signaling Technology, USA; rabbit anti-X-ray repaircross-complementing protein 1 (XRCC1) and anti-Ku70 polyclonal antibodies from Santa CruzBiotechnology, USA; and TUNEL kit from Beijing Huamei Biology, China.METHODS: A total of 108 male, 4-month-old, Sprague Dawley rats were randomly assigned to threegroups, with 36 rats per group. The sham operation group and ischemia/reperfusion group (I/Rgroup) were intracerebroventricularly injected with 10 μL 1% DMSO. The SP600125-treated group(pre-SP group) was given 10 μL SP600125 (3 μg/μL). Thirty minutes later, brain ischemia wasinduced in the I/R and pre-SP groups using the four-vessel occlusion method. Specifically, wholebrain ischemia was induced for 6 minutes, and the clips were released to restore carotid artery bloodflow. Rats from each group were observed at 2, 6, 12, 24, 48, and 72 hours, with 6 rats for each timepoint. The sham operation group was treated with the same surgical exposure procedures, withexception of occlusion of the carotid artery.MAIN OUTCOME MEASURES: Hematoxylin-eosin staining was used to observe neuronal survivalin the hippocampal CA1 region, TUNEL was used to detect apoptosis in the hippocampal CA1region, and immunohistochemistry was used to detect expression of phospho-JNK, XRCC1, andKu70.RESULTS: Following brain ischemia/reperfusion, neuronal survival significantly decreased, and thenumber of apoptotic cells significantly increased (P < 0.01). Compared with the I/R group, neuronalsurvival significantly increased in the pre-SP group, and the number of apoptotic cells significantlydecreased (P < 0.01). Expression of phospho-JNK increased, and XRCC1 and Ku70 significantlydecreased (P < 0.05) following ischemia/reperfusion. Compared with the I/R group, expression ofphospho-JNK decreased, and XRCC1 and Ku70 significantly increased in the pre-SP group (P <0.05). Correlation analysis revealed an inverse correlation between phospho-JNK gray value andXRCC1 and Ku70 gray values in the hippocampal CA1 region (r = -0.983, -0.953, P < 0.01).CONCLUSION: SP600125 treatment decreased apoptosis induced by global brainischemia/reperfusion in the rat hippocampal CA1 region. Results suggested that the neuroprotectiveeffects were due to inhibited phosphorylation of JNK and reduced down-regulation of XRCC1 andKu70. BACKGROUND: Recent studies have shown that the selective inhibitor of c-Jun N-terminal kinases (JNKs) signaling pathway, SP600125, exhibits neuronal protective effects in a rat model of brainischemia / reperfusion. OBJECTIVE: To determine the mechanisms of neuroprotective effects of SP600125 in a rat model of brain ischemia / reperfusion, and determine the role of the JNK signaling pathway in SP600125-induced effects. DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Animal Experiment Center, Medical School of Xi’an Jiaotong University from June 2007 to September 2008. SPECIALS: SP600125 was provided by Biosource, USA; rabbit anti-phospho-JNK (Thr183 / Tyrl85) polyclonal antibody from Cell Signaling Technology, USA; rabbit anti-X-ray repair cross-complementing protein 1 ) and anti-Ku70 polyclonal antibodies from Santa Cruz Biotechnology, USA; and TUNEL kit from Beijing Huamei Biology, China. METHODS: A total of 108 male, 4-month-old, Sprague Dawley rats we The sham operation group and ischemia / reperfusion group (I / Rgroup) were given intracerebroventricularly injected with 10 μL 1% DMSO. The SP600125-treated group (pre-SP group) was given 10 μL SP600125 (3 μg / μL). Thirty minutes later, brain ischemia was induced in the I / R and pre-SP groups using the four-vessel occlusion method. Specifically, wholebrain ischemia was induced for 6 minutes, and the clips were released to The sham operation group was treated with the same surgical exposure procedures, withexception of occlusion of 2 hours, 6, 12, 24, 48, and 72 hours, with 6 rats for each timepoint. the carotid artery. MAIN OUTCOME MEASURES: Hematoxylin-eosin staining was used to observe neuronal survival in the hippocampal CA1 region, TUNEL was used to detect apoptosis in the hippocampal CA1 region, and immunohistochemistry was used to detect expression of phospho-JNK, XR CC1Compared with the I / R group, neuronalsurvival significantly increased in the pre-SP group, and the number Expression of phospho-JNK increased, and XRCC1 and Ku70 significantly decreased (P <0.05) following ischemia / reperfusion. Compared with I / R group, expression of phospho-JNK decreased, and XRCC1 and Ku70 significantly increased in the pre-SP group (P <0.05). Correlation analysis revealed an inverse correlation between phospho-JNK gray value and XRCC1 and Ku70 gray values ​​in the hippocampal CA1 region (r = -0.983, -0.953, P <0.01). CONCLUSION: SP600125 treatment decreased apoptosis induced by global brainischemia / reperfusion in the rat hippocampal CA1 region. Results suggested that the neuroprotective effects were due to inhibited phosphorylation of JNK and reduce d down-regulation of XRCC1 andKu70.