The localization of galanin (GAL) and GAL mRNA was studied in rat brain after colchicine or vinblastine treatment using in situ hybridization and immunohistochemistry. GAL-like immunoreactivity was found in glial cells, presumably activated microglia, in the cortex, caudate nucleus and septum, mainly on the injection side. GAL mRNA expression was found in small cells in the same areas with an overlapping distribution, including the adjacent white matter. The results suggest that the glial cells initiate synthesis of the peptide GAL in response to intraventricular injection of high doses of the 2 mitosis inhibitors.