Neuronal damage in hippocampal subregions induced by various durations of transient cerebral ischemia in gerbils using Fluoro-Jade B histofluorescence

Although there are many studies on ischemic brain damage in the gerbil, which is a good model of transient cerebral ischemia, studies on neuronal damage according to the duration of ischemia–reperfusion (I–R) time are limited. We carried out neuronal damage in the gerbil hippocampus after various durations of I–R (5, 10, 15 and 20 min) using Fluoro-Jade B (F-J B, a maker for neuronal degeneration) histofluorescence as well as cresyl violet (CV) staining. The changes of CV positive (+) neurons were well detected in the hippocampal CA1 region, not in the other regions. F-J B histofluorescence staining showed apparent neuronal damage in all the hippocampal subregions. In the CA1, most of the pyramidal neurons of the stratum pyramidale (SP) were stained with F-J B (about 100/mm2 in a section), and F-J B+ neurons in the other ischemia-groups were not changed. In the CA2, a few F-J B+ neurons were detected in the SP of the 5 min ischemia-group, and F-J B+ neurons were gradually increased with the longer time of ischemia: in the 20 min ischemia-group, the mean number of F-J B+ neurons was about 85/mm2 in a section. In the CA3, some F-J B+ neurons were observed only in the SP of the 20 min ischemia-group. In the dentate gyrus, some F-J B positive neurons were detected only in the polymorphic layer (PL) of the 5 min ischemia-group, and the number of F-J B+ neurons were gradually increased with the longer ischemic time. Our findings indicate that F-J B histofluorescence showed a very high quality of neuronal damage in all the hippocampal subregions.

► Fluoro-Jade B (F-J B) histofluorescence was very good for neurodegeneration according to ischemic duration.
► In hippocampal CA1, most of pyramidal neurons were similarly stained with F-J B regardless of ischemic duration.
► In CA2, F-J B+ neurons occurred from 5 min of ischemia, and they increased gradually with a longer duration.
► In CA3, some F-J B+ pyramidal neurons were observed only in the long-lasting (20 min) ischemia-group.
► In the dentate gyrus, F-J B+ neurons happened from 5 min of ischemia, and they increased gradually with a longer duration.