Fig. 1. Overview of the generation of ApoE-conditional knockout animals and experimental outline.

a To generate ApoE-conditional knockout mice, exon 1 and exon 2 of the ApoE gene were flanked with loxp sites to allow for cre-dependent recombination. The primers for genotyping were designed to flank exon 2 of the ApoE gene with or without one of the loxp sites. b Timeline of experiments. Mice received tamoxifen at three weeks of age. At six weeks of age, sham or CCI surgery was performed. A subset of mice received eGFP-expressing retrovirus targeted to the dentate gyrus at the conclusion of surgery. Four weeks after viral infection, mice were perfused to analyze the morphology of newborn neurons or stained using Golgi–Cox method. Habituation was performed on the remaining mice. Following habituation, the elevated plus maze, open field, Morris water maze, and contextual fear-conditioning tasks were performed. c The 500 bp DNA fragment generated by PCR indicates mice without the loxp-flanked ApoE, the 750 bp result indicates mice with two copies of loxp-flanked ApoE, and the hemizygous mice generate one 500-bp and one 750-bp fragment.