Superoxide radical generation and histopathological changes in hippocampal CA1 after ischaemia/reperfusion in gerbils

We investigated the relationship between the generation of superoxide radicals and histopathological changes on delayed neuronal death in the hippocampal CA1 subfield.

Seventy gerbils were randomly assigned to two groups, a sham group and an ischaemia/reperfusion (I/R) group. In the I/R group, transient forebrain ischaemia was induced by occluding the bilateral common carotid arteries for four minutes. The cerebrum was removed after reperfusion at intervals of one minute, six, twelve and twenty-four hr and at three, five and seven days. Each forebrain was cut into two portions including the hippocampus. The quantity of superoxide radicals was measured by using chemiluminescence, and histopathological changes in the hippocampal CA1 subfield were examined.

In the I/R group, superoxide radicals increased on the 3rd and 5th days compared with the sham group (16.1 +/- 3.4 vs 3.2 +/- 1.0 on the third day (P < 0.0001); 10.9 +/- 1.9 vs 3.3 +/- 0.8 on the fifth day (P < 0.0001)). In the I/R group, the pyramidal cells were atrophic and pycnotic; vacuolation, and structural disruption of the radial striated zone were observed from the third through the seventh day. In the sham group, these changes were not observed. There were differences of degenerative ratios in the pyramidal cells between the two groups from the third to seventh days (5.6 +/- 2.0 vs 80.9 +/- 3.3 on the third day (P < 0.05); 6.9 +/- 0.4 vs 93.6 +/- 2.4 on the fifth day (P < 0.05); 6.2 +/- 1.5 vs 95.0 +/- 1.3 on the seventh day (P < 0.05)).

There is a correlation between the generation of superoxide radicals and histopathological changes of the pyramidal cells in the hippocampal CA1 subfield.