Abstract: Objective To investigate the relationship between active Caspase-3 and apoptosis in Wistar rat hippocampus during postnatal development. Methods Immunofluorescent staining was applied to observe the expression of active Caspase-3 and Hoechst 33342 in the CA1, CA3 and dentate gyrus（DG）of rat hippocampus during postnatal development. Results The expression of active Caspase-3 reached a peak at postnatal day 7(P7) in CA1, at P2 in CA3, then decreased with age. Whereas in DG, active Caspase-3 expression increased slightly after P7, reaching a maximum at P14, and remained at high levels for the rest of the investigated period. In addition, the number of apoptotic cells in the three regions all reached maximum levels at P7, then decreased with age. Conclusion There are specific spatiotemporal patterns of expression of active Caspase-3 in the postnatally developing rat hippocampal subregions and active Caspase-3 in the postmitotic neurons of CA1 and CA3 and in neuronal progenitor cells of DG may have distinct roles and mechanisms

Key words: Caspase-3, Development, Hippocampus, Immunofluorescence, Rat