Comparative study on Cu,Zn-SOD immunoreactivity and protein levels in the adult and aged hippocampal CA1 region after ischemia–reperfusion

In the present study, we investigated chronological changes in Cu,Zn-superoxide dismutase (SOD1) immunoreactivity and its protein levels in the hippocampal CA1 region of adult and aged gerbils after transient forebrain ischemia to compare ischemia-related changes in SOD1 in adult and aged gerbils. Delayed neuronal death in the CA1 region at 4 days after ischemic insult was prominent in adult gerbils compared to that in aged gerbils. In sham-operated gerbils, SOD1 immunoreactivity and protein level in the aged group were significantly higher than that in the adult group. At 12 h after ischemia–reperfusion, SOD1 immunoreactivity and protein level were increased in both the groups. At 1 day after ischemia, SOD1 immunoreactivity and protein level in the adult group were significantly increased: the SOD1 immunoreactivity was increased in non-pyramidal cells as well as pyramidal cells. At this time after ischemia, SOD1 immunoreactivity and protein level in the aged group were decreased: the immunoreactivity was decreased significantly in pyramidal cells. At 4 days after ischemia, SOD1 immunoreactivity was detected only in non-pyramidal cells of the CA1 region in both the groups. These results suggest that SOD1 in the gerbil hippocampal CA1 region is higher in sham-aged group than that in sham adult one, and that different changes in SOD1 in CA1 pyramidal cells after ischemia in adult and aged gerbils may indicate different processes in delayed neuronal death with time after ischemic insult.