, 1999) ( Figure S3C). Exposure to enrichment for 3 weeks significantly increased hippocampal neurogenesis in wild-type mice (nonenriched versus enriched [normalized to nonenriched selleck inhibitor wild-type]: 1.00 ± 0.08 versus 1.71 ± 0.20, p = 0.0302, two-tailed t test) ( Figure S3D), consistent with previous reports ( Kempermann et al., 1997 and van Praag et al., 1999). Compared with nonenriched wild-type mice, nonenriched Bdnf+/− mice showed reduced neurogenesis (wild-type versus Bdnf+/− [normalized to nonenriched wild-type]:

1.00 ± 0.08 versus 0.69 ± 0.04, p < 0.05, post hoc Dunnett's test) ( Figure S3D), as previously reported ( Lee et al., 2002 and Sairanen et al., 2005). In contrast to wild-type mice, Bdnf+/− mice did not show any increase in neurogenesis after enrichment (nonenriched versus enriched [normalized to nonenriched wild-type]: 0.69 ± 0.04 versus 0.79 ± 0.08, p = 0.3792, two-tailed t test) ( Figure S3D). This result is consistent with

previous reports ( Rossi et al., 2006). Meanwhile, neurogenesis of nonenriched Kif1a+/− mice was comparable to that of nonenriched wild-type Raf inhibitor mice (wild-type versus Kif1a+/− [normalized to nonenriched wild-type]: 1.00 ± 0.08 versus 1.04 ± 0.10, p > 0.05, post hoc Dunnett’s test) ( Figure S3D). Interestingly and consistent with wild-type mice, Kif1a+/− mice exhibited enhanced hippocampal neurogenesis after enrichment (nonenriched versus enriched [normalized to nonenriched wild-type]: 1.04 ± 0.10 versus 1.58 ± 0.16, p = 0.0450, two-tailed t test) ( Figure S3D). These results suggest that KIF1A is not required for enhanced hippocampal

neurogenesis induced by enrichment. To analyze the possible BDNF-dependent upregulation of KIF1A in more detail, we first examined the effects of BDNF on KIF1A levels in cultured hippocampal neurons. Quantitative immunoblot analyses revealed that there was an increase in KIF1A levels in BDNF-treated neurons in a time-dependent (BDNF-treated/nontreated ratio: 1 day, 1.19 ± 0.07, p = 0.0471; 3 days, 1.62 ± 0.07, p < 0.001; 5 days, 1.67 ± 0.05, p < 0.001, two-tailed t test) (Figure 4A) and dose-dependent manner (BDNF concentration [ng/ml], ratio to crotamiton 0 ng/ml: 10 ng/ml, 1.40 ± 0.05, p = 0.0016; 50 ng/ml, 1.55 ± 0.05, p < 0.001; 100 ng/ml, 1.64 ± 0.07, p < 0.001; 200 ng/ml, 1.67 ± 0.07, p < 0.001, two-tailed t test) (Figure 4B). This upregulation of KIF1A was completely blocked by K252a, a general inhibitor of Trk tyrosine kinase (BDNF+K252a-treated/non-treated ratio: 1.02 ± 0.06, p = 0.6843, two-tailed t test) (Figure 4C). The level of Kif1a mRNA was also increased (BDNF-treated/non-treated ratio: 1 day, 1.22 ± 0.05, p = 0.0487; 3 days, 1.64 ± 0.04, p = 0.0047; 5 days, 1.70 ± 0.07, p = 0.