Effects of intraplantar injection of carrageenan on central dopamine release.

The present study examined the changes of extracellular concentration of dopamine and its metabolite homovanillic acid in the striatum, the periaqueductal gray and the dorsal horn of lumbar spinal cord following intraplantar injection of carrageenan. In vivo microdialysis and high-performance liquid chromatography with electrochemical detection were performed. The results showed that intraplantar injection of carrageenan significantly increased dopamine or homovanillic acid levels in the different central regions. The present study suggested that the central dopamine system (at least including ascending nigrostrialtal pathway and descending A11--the dorsal horn fibers) be activated following the carrageenan, while the activation probably mediated antinociception.