Cerebral neurons express interleukin-6 after transient forebrain ischemia in gerbils

Markedly increased interleukin-6 (IL-6) mRNA levels occur in experimental c erebral ischemia, although the protein production and cellular sources of I L-6 remain unclear. We examined the cellular localization of IL-6 protein i n gerbil brain following transient forebrain ischemia employing immunohisto chemistry and Western blot analysis. The ischemia/recirculation groups reve aled distinct IL-6 immunoreactivity predominantly in cortical and hippocamp al neurons after 3 hours to 3 days recirculation. At 12 h recirculation, th e IL-6 expression declined specifically in the hippocampus CA1. Microglia, but not activated astrocytes, also expressed IL-6 immunoreactivity. The sha m group showed no apparent immunoreactivity. IL-6 protein may thus be expre ssed mainly in neurons following transient forebrain ischemia. Its transien t decline in the CAI at 12 h recirculation could reflect the specific vulne rability of this region. (C) 1999 Published by Elsevier Science Ireland Ltd . All rights reserved.