Development of Anxious-Depression-Related Behavior Figure 1. Behavioral effects of tamoxifen in the EPMT and FST independent of target gene recombination. TAM was injected into CAGGCre-ERTM, fc2/+ and WT littermates at P13/14 or P27/28 to test for TAM- and Cre-induced behavioral effects at 8–10 weeks of age that occurred independently of recombination of the fc2 locus. a) In the EPMT, the CAGGCre-ERTM and fc2/+ mice visited open arms and stayed in the open arms as much as WT mice. b) In the FST, the behavior of fc2/+ mice was indistinguishable from WT mice. CAGGCre-ERTM mice showed a normal latency to immobility and reduced immobility duration compared to TAM-treated fc2/+ and WT mice. All values represent group means 6 SEM. *p,0.05, Dunnett’s test. doi:10.1371/journal.pone.0047441.g001 Figure 2. Developmental control of anxious depressive behavior induced by tamoxifen-induced Cre-mediated recombination of the fc2 locus. a) Experimental time line. Littermates representing all three genotypes were injected with TAM at P13/14 or P27/28, followed by behavioral testing starting after 8 weeks of age. b) In the EPMT, CAGGCre-ERTM X fc2/+ mice treated with TAM at P13/14 visited the open arm less often than identically treated fc2/+ and CAGGCre-ERTM controls. Moreover, P13/14 TAM-treated CAGGCre-ERTM X fc2/+ mice spent less time on the open arms than identically treated fc2/+ controls, while the number of closed arm entries was unaffected. c) CAGGCre-ERTM X fc2/+ mice treated with TAM at P27/P28 were indistinguishable from identically treated fc2/+ and CAGGCre-ERTM littermate controls with respect to % open arm entries, % time spent on open arms, and number of closed arm entries. d) In the FST, the latency of P13/14 TAM-treated CAGGCre-ERTM X fc2/+ mice to float was reduced compared to identically treated CAGGCre-ERTM and fc2/+ littermate controls. Moreover, P13/14 TAM-treated CAGGCre-ERTM X fc2/+ mice showed increased immobility compared to identically treated CAGGCre-ERTM controls. e) P27/28 TAM-treated CAGGCre-ERTM X fc2/+ mice were indistinguishable from identically treated fc2/+ and CAGGCre-ERTM littermates with respect to both latency to immobility and immobility duration. f) In the OFT, the distance traveled of P13/14 TAM-treated CAGGCre-ERTM X fc2/+ mice over a period of 15 min was indistinguishable from that of identically treated CAGGCre-ERTM and fc2/+ littermates. All values represent group means 6 SEM. *p,0.05, **p,0.01, ***p,0.001, Dunnett’s tests. doi:10.1371/journal.pone.0047441.g002 PLOS ONE | www.plosone.org 5 October 2012 | Volume 7 | Issue 10 | e47441