These results indicate that the induction of GC apoptosis during feeding and postprandial period occurs globally in all regions of the OB. To determine the cellular ages of GCs that showed enhanced apoptosis during the feeding and postprandial period, we first labeled adult-born new GCs by BrdU injection. We classified the new GCs into four subsets with different

cellular ages; those aged 7–13 days, 14–20 days, 21–27 days, and 28–34 days, and then examined PD-0332991 nmr the apoptosis in each subset (Figures 2A and 2B). Subsets of new GCs within the critical period for the survival and death decision, aged 14–20 days and 21–27 days (Yamaguchi and Mori, 2005), showed enhanced apoptosis during feeding and postprandial period (Figure 2B, green bars). Given that BrdU injection cannot label all proliferating cells (Taupin, 2007), the results indicate that new Afatinib chemical structure GCs aged 14–20 days constitutes at least 24.5% of caspase-3-activated GCs and GCs aged 21–27 days constitutes at least 22.6% (Figure 2C). New GCs after the critical period (days 28–34) also showed enhanced apoptosis during the time window, although their contribution to total apoptotic cell

ratio was smaller (9.5%). Interestingly, new GCs before the critical period (days 7–13) showed no significant enhancement in apoptosis during the feeding and postprandial period (Figure 2B; see Discussion). Thus caspase-3-activated GCs is comprised of at least 7.8% of new GCs aged 7–13 days, 24.5% of new GCs aged 14–20 days, 22.6% of new GCs aged 21–27 days, and 9.5% of new GCs aged 28–34 days. Rough approximation by summating the percentage of each new GC subset suggests that more than 64% of caspase-3-activated GCs are new GCs aged day 7 to 34, indicating that the majority of the

apoptotic GCs were adult-born new GCs. This notion was supported by the coexpression of doublecortin (DCX) in many caspase-3-activated GCs (40%–46%) (Figures 2A and S2A; Brown et al., 2003). The total number of BrdU-labeled GCs per OB did not significantly differ before and at 2 hr after the start of feeding in all periods examined (Figure S2B), indicating that the increase in apoptotic GCs during feeding and postprandial period was not due to any rapid recruitment of new GCs in the OB. Neonate-born GCs are gradually eliminated in the adult period (Imayoshi et al., 2008). SB-3CT To examine whether preexisting neonate-born GCs also showed increased apoptosis during feeding and postprandial period, they were BrdU-labeled on postnatal days 4-5 and examined in adulthood (Figures 2D and S2C–S2E). Although the number was small, caspase-3-activated GCs with BrdU labeling were observed and increased by 2-fold at 2 hr after food supply. Thus, neonate-born, preexisting GCs also showed increased apoptosis during the feeding and postprandial period. Adult neurogenesis also occurs in GCs of the hippocampal dentate gyrus (DG) (Lledo et al., 2006 and Zhao et al., 2008).