Abstract： Objective:To explore the role of c-Jun amino-terminal kinase (JNK) signaling pathway in the proliferation of hippocampal neural stem cells (NSC) in mice with traumatic brain injury (TBI) .Methods:Thirty-six 4- to 6-week-old male C57BL/6 mice were selected, and randomly assigned into sham group, model group (TBI modeling induced using controlled cortical impact method) , and JNK inhibitor group (modeling + intraperitoneal injection of JNK inhibitor SP600125) . The neurological function was assessed using modified Neurological Severity Score (mNSS) , and brain water content was measured in all three groups. The synaptic ultrastructure of hippocampal neurons was observed by transmission electron microscopy, the proliferation of NSC (BrdU/Sox2-colabeled cells) was detected by immunofluorescence staining, and the expression of autophagy-associated proteins (LC3-Ⅱ, Beclin1, Atg5) and JNK signalling related proteins in the hippocampus was measured by Western blotting.Results:Compared with sham group, model group detected elevated mNSS score, increased brain water content, larger number of BrdU/Sox2-colabeled cells in hippocampal regions (30.6±2.8 vs 114.2±3.9) , and up-regulated relative expression of LC3-Ⅱ, Beclin1, Atg5, JNK, and p-JNK proteins. The abnormality elevated modified mNSS scores, increased brain water content, and up-regulated relative expression of LC3-Ⅱ, Beclin1, Atg5, JNK, and p-JNK proteins were all attenuated in JNK group compared to model group, and the number of BrdU/Sox2-colabeled cells in hippocampal regions was (137.43±3.40) in JNK inhibitor group, which was larger than that of model group, with statistical difference ( P<0.05) . Transmission electron microscopy showed that the nucleus of hippocampal CA1 neurons in sham operation group was normal. In model group, the nerve cell structure in the hippocampal CA1 region showed varying degrees of expansion or swelling, and the nucleus appeared fusion. The cell structure in JNK inhibitor group showed a small amount of expansion and swelling, and mild fusion of the nuclear membrane. Conclusion:Inhibition of the JNK signaling pathway improves the proliferation of NSC in the hippocampus of TBI mice and ameliorates neurological function by modulating the level of autophagy.