Objective To investigate the effects of intrathecal injection of Akt inhibitor Ⅳ on pain behavior in rats model of injected radicular pain. Methods Eighteen male Sprague Dawley (SD) rats with successful intrathecal intubation were randomly divided into three groups (n=6): Sham group (S), injected radicular pain group (C), and Akt inhibitor group (A). In C group and A group, the model of injected radicular pain were established by surgiflo injection. Akt inhibitorⅣ was injected 30 min before the model preparation in group A. Vehicle (10% ethanol) was intrathecally injected at the same time in group C and group S. Pain ethology indexes such as paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were assessed on 1 d before and 1, 4, 7, 10, 17 d and 28 d after operation. Results Compared to group S and preoperative level, PWMT and PWTL were decreased on the first postoperative day in group C (P<0.05). Intrathecal Akt inhibitorⅣ injection significantly decreased PWMT and PWTL (P<0.05) in groups A. Conclusion Intrathecal Akt inhibitorⅣ injection would intensify pain behavior in rat model of injected radicular pain. Akt may play an important role in the development of pain behavior in rat model of injected radicular pain. Key words: Akt ; Injected radicular pain ; Pain behavior ;