Interleukin 1β has been reported to be involved in pain modulation in central n ervous systems. As the spinal cord is a major region in which nociceptive input is processed and modulated

we examined the effect of intrathecal injection of i nterleukin 1β on the nociception in carrageenan injected rats using behavior a nd Fos study. The results showed that: ① intrathecally administered interleu kin 1β (1 ng

10 ng and 100 ng) could dose dependently increase the thermal n ociceptive threshold of carrageenan inflammed rats. Intrathecally administered interleukin 1β 10 ng could significantly increase the paw withdrawal latency

peaked at 15 min and lasted for more than 30 min. Electroacupuncture (EA) unilat eral (ipsilateral to carrageenan injection paw) "Zusanli"(ST 36) and "Kunlun "(BL 60) acupoints (2 and 60 Hz alternately

1～3 mA

30 min) significantly eleva ted the nociception threshold of the carrageenan injected paws. When 10 ng inte rleukin 1β was intrathecally injected 5 min before the beginning of EA

the ef fect of EA analgesia was markedly potentiated. ② The number of Fos LI neurons in the ipsilateral spinal dorsal horn was significantly increased in laminae Ⅰ ～Ⅱ and laminae Ⅴ～Ⅵ in carrageenan injected rats. Intrathecal administratio n of interleukin 1β could suppress the expression of Fos LI in laminae Ⅰ～Ⅱ

but not in laminae Ⅲ～Ⅳ or laminae Ⅴ～Ⅵ. The number of Fos LI positive n eurons both in laminae Ⅰ～Ⅱ and in laminae Ⅴ～Ⅵ in EA treated rats was sign ificantly less than that of vehicle treated rats. When 10 ng interleukin 1β wa s intrathecally injected 5 min before the beginning of EA

the number of Fos LI positive neurons both in laminae Ⅰ～Ⅱ and in laminae Ⅴ～Ⅵ was markedly le ss than either of those in EA treated rats or in interleukin 1β treated rats. The results suggest that interleukin 1β in spinal level could produce antinoci ceptive effect and strengthen acupuncture analgesia in inflammatory rat.