ABCA1 and major depressive disorder: Although depression-like behaviors did not differ between the two groups of mice at the end of the CUMS protocol (Figures 5F–5J), the behavioral results described above strongly suggest that V1 neuronal ABCA1-deficient mice are more susceptible to CUMS, indicating that neuronal ABCA1 deficiency in the V1 may be an essential condition for development of depression under chronic stress conditions.