Fig. 4.

Anxiety in light-dark choice and elevated plus-maze tests. Both tests were performed in the same 2-month-old groups of mdx mice (n=15) and their wild-type (WT) littermates (n=14), and in mdx52 mice (n=12) and their wild-type littermates (n=9). (A-F) Light-dark choice test. (A) Schematic representation of the light/dark test apparatus (top view) composed of a dark box (15×15 cm), in which each mouse was first introduced, and a lit box (40×15 cm). The two compartments were connected by a sliding door. The lit box was separated in half by a virtual line (dotted line) to analyze behavior in the first and second parts of this box, which had different light intensities; the light intensity gradient is shown above the drawing. The end part of the lit box (600 lx) was considered to be more anxiogenic than the first part near the door (50 lx). Parameters were measured for 5 min. (B) Latency of the first entry into the lit box (s). (C) The number of entries in the lit box. (D) Time spent in the lit box. (E) Number of crossings of the virtual line. (F) Time spent beyond the virtual line, i.e. in the most anxiogenic part of the apparatus. (G-I) Elevated plus maze. Behavioral parameters were analyzed for 5 min. (G) Number of entries in open arms, expressed as percentage of total number of arm entries. (H) Percentage time spent in open arms. (I) Number of head dips made in closed arms (protected) and in open arms (unprotected). Data are mean±s.e.m. ***P<0.001; **P<0.01; *P<0.05; ns, not significant (Kruskal–Wallis test followed by Dunn's test).