Increase in basal level of Hsp70, consisting chiefly of constitutively expressed Hsp70 (Hsc70) in aged rat brain

Alteration of proteins in the function and higher structure has been observ ed in aged organisms. Stress proteins, which have a role to protect protein s from denaturation, may respond to the protein denaturation with aging. We found that the basal level of Hsp70, consisting chiefly of constitutively expressed Hsp70 (Hsc70), in 24-month-old Wistar rats was significantly high er in some parts of the brain than that in 6-month-old rats. On the other h and, the basal level of Hsp70 was significantly lower in 24-month-old rats after restricted feeding, which is known to suppress aging, than those fed the diet ad libitum. In the pens, medulla, striatum, and thalamus of 24-mon th-old rat brain, the level of Hsp70 increased and the denaturation of the cytosol proteins was suppressed. These results suggest that the expression of Hsp70, mostly Hsc70, increases with aging and may have a role to suppres s protein denaturation.