Differential regulation of metallothionein-I, II, and III mRNA expression in the rat brain following kainic acid treatment

Although metallothioneins (MTs) are believed to be involved in the protection against neural stresses, spatio-temporal regulation of MT isoforms following neural insults has not been thoroughly examined. In this study, we found that systemic application of kainic acid (KA) rapidly induced MT-I and II expression in neurons localized in hippocampal formation, piriform cortex, and amygdala of the adult rat, whereas the level of MT-III mRNA was decreased in KA-vulnerable areas. At 96 h after KA treatment, while the neuronal expression of MT-I and II returned to basal level, the glial expression of MT-I, II and III was increased in the reactive astrocytes. Differential regulation of MT isoforms in neuron and gila suggests that each isoform might have distinct role in the cell-type dependent cellular responses against KA-evoked neural injuries.