Objective Numerous evidence suggests that spinal astrocytes play an important role in chronic pain through release of neuroactive substances, such as interleukin and ATP.Glutamate produces marked effects in initiation and transmission of nociceptive information.However, there is a lack of direct evidence that how glutamate activate astrocytes and whats effects of activated astrocytes by glutamate on pain mechanisms.This study therefore explored the direct effects of glutamate activation of spinal astrocytes.Methods Primary culture of spinal astrocytes were administered with glutamate.The levels of protein and rnRNA expression of IL-6, which reflect astrocyte activation, were determined by ELISA assay and real-time PCR.The spinal astrocytes activated by glutamate were injected into the lumber enlargement of adult Wistar rats, and paw withdrawal latency (PWL) was tested.Results Administration of glutamate (1 000 μM) activated astrocytes from 6 h after intrathecal injection and reached the maximal level at 24 h (the last time point we explored).Besides, glutamate (1 000 μM) enhanced the release of IL-6 by astrocytes.Intrathecal injection of cultured spinal astrocytes, which were stimulated by glutamate, induced a substantial decrease of PWL, indicating the development of thermal hyperalgesia.Conclusion Our results suggest that activated astrocytes by glutamate is sufficient to produce thermal hyperalgesia in rats by releasing IL-6.