Delayed induction of αB-crystallin in activated glia cells of hippocampus in kainic acid-treated mouse brain

Small heat shock proteins have been implicated in playing a role in various cellular processes, including stress-induced cell death. In kainic acid (KA)-treated rat brain, the immunoreactivity of heat-shock protein 27 (HSP27) was markedly increased in glia cells of the limbic system. In the present study, we demonstrated that αB-crystallin, a member of the small heat-shock protein family, was strongly induced in reactive astrocytes in hippocampus after KA-induced seizure. The induction was localized mainly in the CA3 region of hippocampus, where massive neuronal loss occurred. We also demonstrated that the delayed induction of αB-crystallin and HSP27 immunoreactivities in the hippocampus of epileptic animals was repressed to the levels seen in control animals with preadministration of the selective nNOS inhibitor 7-nitroindazole (7-NI). This repression was reversed by coinjection of L-arginine, a substrate of NOS. Together, these data suggest a role for αB-crystallin and HSP27 in reactive gliosis and/or in delayed neuronal death proceeded after KA-induced seizure.