Different expression of caspase‐3 in rat hippocampal subregions during postnatal development

Abstract

Recent studies indicate that caspase-3 has distinct characteristics in postmitotic and neuronal progenitor apoptosis. Pyramidal neurons in CA1 and CA3 of the hippocampus become postmitotic during early postnatal development, whereas granule cells in the dentate gyrus (DG) undergo self-renewal throughout life. The distribution of caspase-3 in the hippocampal subfields during postnatal development is largely unknown. We used immunofluorescent staining for two isoforms of caspase-3 (an active 17 kDa isoform and an inactive 35 kDa precursor) and the Hoechst 33342 staining for nuclear chromatin to assess caspase-3 expression in the CA1, CA3, and DG of rat hippocampus during postnatal development. The expression of active caspase-3 reached a peak at P7 in CA1, at P2 in CA3, and then decreased with age. Whereas in DG, active caspase-3 expression increased slightly after P7, and remained at high levels for the rest of the investigated period. Procaspase-3 immunoreactivity was strong at P2 and decreased gradually to a basal plateau by P21 in the three regions examined. In addition, the number of apoptotic cells in the three regions all reached maximum levels at P7, and then decreased with age. These data indicate that there were specific spatio-temporal patterns of expression of active and precursor caspase-3 in the postnatally developing rat hippocampal subregions, and that the activation of caspase-3 in neuronal progenitor cells of DG and that in the postmitotic neurons of CA1 and CA3 may have distinct roles and mechanisms during postnatal development.

Immunoreactivity of Ki-67/β-tubulin and immunocolocalization with active caspase-3 in rat dentate gyrus during postnatal development

“…1, 2A and 3). There were a substantial number of Ki-67-labeled cells throughout the dentate gyrus of newborn rats ( Figs Consistent with our previous report (Liu et al, 2008), in the present study, the immunoreactive cells of active caspase-3 were expressed in GCL and the adjacent layers of DG, and maintained a higher level in GCL and SGZ at all the investigated ages (P0-P56) (Figs. 2B and 3).…”

“…A recent study reported that caspase-3 plays a critical role in LTD induction (Li et al, 2010). NMDA-receptor dependent LTD in CA1 neurons is abolished in caspase-3 knockout mice, whereas LTP can be induced normally (Li and Sheng, 2012). Another research on the zebra finch auditory forebrain showed caspase-3 activity is necessary for memory consolidation during birdsong learning, and novel-song exposure causes active caspase-3 rapidly released into dendritic spines (Huesmann and Clayton, 2006).…”

“…Our previous study has demonstrated that active caspase-3 maintains a high level of expression in dentate gyrus (DG), which is asynchronous with apoptotic cell death in DG during postnatal development (Liu et al, 2008). We addressed the hypothesis that active caspase-3 may play a role in proliferation, differentiation or maturation of granular cells.…”

Different expression of NR2B and PSD‐95 in rat hippocampal subregions during postnatal development

“…On the one hand, the higher levels of NR2B in granular cell layer and the stratum moleculare may correlate with the characteristic of granule cells in DG, which continued to undergo self-renewal throughout life (Liu et al, 2008;Lu et al, 2005). Because NR2B is predominately expressed in juveniles, neurons interact with RasGRF1.…”

Organelle and Cellular Abnormalities Associated with Hippocampal Heterotopia in Neonatal Doublecortin Knockout Mice

“…We examined apoptosis at P2, a peak stage of cell death during rodent postnatal hippocampal development [37], [38]. Cells expressing activated caspase-3 were identified across the rostro-caudal extent of the Dcx KO dorsal hippocampus compared to WT littermate hippocampi.…”