Light/Dark Transition Test in Mice

On day 16, the LDTT was conducted (Figure 1B), as formerly defined (Li et al., 2006 (link); Martinho et al., 2020 (link); Silvestri et al., 2020 (link); Martinho et al., 2021 (link)). The apparatus consisted of a wooden box without a lid comprising a light (50 × 30) and a dark compartment (50 × 20) with 25 cm high walls. The different areas were joined by a square entrance (10 × 10 cm), which remained open during the entire duration of the test. The test started by placing each animal into the light area facing the opposite wall to the entrance. A Sony digital video camera (Sony Corporation, Japan) was positioned above the apparatus and used to record the mice’s behavior, namely the time spent in the light area, the number of passages to the light area, and the total number of passages between dark and light areas. The test lasted for a total of 5 min, and results were obtained from manual and blind analyzes of the resulting videos.