The present study was aimed to examine changes of extracellular concentration of dopamin e and its metabolite homovanillic acid in the striatum

the periaqueductal gray matter and the dorsal horn of lumbar spinal cord following intraplantar injecti on of ca rrageenan. In vivo microdialysis and high performance liquid chromatography wit h electrochemical detection were performed. The results showed that intraplantar injection of carrageenan significantly increased dopamine or homovanillic acid l evels in the different central regions. The present study suggested that the cen tral dopamine system (at least including ascending nigrostriatal pathway and des cending A 11 --the dorsal horn fibers) could be activated following intrap lantar injection of carrageenan

while the resultant activation probably mediate d antinociception.