Abstract： Background C-Jun N-terminal kinase (JNK) signaling pathway plays a critical role in cerebral ischemia.Although the mechanistic basis for this activation of JNK1/2 is uncertain,oxidative stress may play a role.The purpose of this study was to investigate whether the activation of JNK1/2 is associated with the production of endogenous nitric oxide (NO).Methods Ischemia and reperfusion (I/R) was induced by cerebral four-vessel occlusion.Sprague-Dawley (SD) rats were divided into 6 groups:sham group,I/R group,neuronal nitric oxide synthase (nNOS) inhibitor (7-nitroindazole,7-NI)given group,inducible nitric oxide synthase (iNOS) inhibitor (2-amino-5,6-dihydro-methylthiazine,AMT) given group,sodium chloride control group,and 1％ dimethyl sulfoxide (DMSO) control group.The levels of protein expression and phospho-JNK1/2 were detected by Western blotting and the survival hippocampus neurons in CA1 zone were observed by cresyl violet staining.Results The study illustrated two peaks of JNK1/2 activation occurred at 30 minutes and 3 days during reperfusion.7-NI inhibited JNK1/2 activation during the early reperfusion,whereas AMT preferably attenuated JNK1/2 activation during the later reperfusion.Administration of 7-NI and AMT can decrease I/R-induced neuronal loss in hippocampal CA1 region.Conclusion JNK1/2 activation is associated with endogenous NO in response to ischemic insult.