Heat shock protein 90 and its cochaperone, p23, are markedly increased in the aged gerbil hippocampus

In the present study, we compared HSP90 and its co-chaperone, p23, immunoreactivity and their protein levels in the hippocampus between adult (postnatal month 6) and aged (postnatal month 24) gerbils using immunohistochemistry and western blot analysis. HSP90 immunoreactivity was markedly increased in pyramidal cells in the hippocampus proper and in polymorphic cells in the dentate gyrus of the aged group compared to the adult group. p23 immunoreactivity was slightly increased in pyramidal cells of the hippocampus proper and in granule cells of the dentate gyrus in the aged group. In addition, HSP90 and p23 protein levels in the aged hippocampus were much higher than the adult hippocampus. These results indicate that HSP90 and p23 immunoreactivity and protein levels in the hippocampus are distinctively increased in the aged gerbils compared to the adult gerbils.