Fig. 1: Social hierarchy and hormonal profile of group-housed mice.

a Schematic of the experimental design: 34 groups of four male mice were subjected to the tube test. At the end of this testing period, blood samples were taken for measurement of corticosterone levels. Mice were then exposed to a courtship vocalization test, followed by measurement of blood testosterone and spleen noradrenaline levels (14 groups), or received DNA vaccination (20 groups; see Fig. 2). b Tube-test scores on each test day (n = 34 groups). Social ranks are based on performance on the last 5 test days (yellow). c Percentage of hierarchy stability during the last 5 test days. d Example vocalization (left) and the amount of vocalization relative to the group average per rank of social groups (n = 9). e Weight of mice per rank (n = 14 groups). f–h Blood testosterone per rank of social groups (n = 14) in absolute levels (f), relative to the group average (g), and relative to the group average split between 100% (orange; n = 6) and < 100% (yellow; n = 8) hierarchy stability (h). i–k Blood corticosterone per rank of social groups (n = 29) in absolute levels (i), relative to the group average (j), and relative to the group average split between 100% (orange; n = 17) and < 100% (yellow; n = 12) hierarchy stability (k). l–n Noradrenaline levels in spleen per rank of social groups (n = 12) in absolute levels (l), relative to the group average (m), and relative to the group average split between 100% (orange; n = 5) and < 100% (yellow; n = 7) hierarchy stability (n). Black square: rank 1; dark-gray circle: rank 2; gray diamond: rank 3; light-gray triangle: rank 4. Data are mean ± SEM. *P < 0.05, **P < 0.01. Statistics: one-way ANOVA with Tukey’s multiple-comparison test (e–n) and Pearson’s correlation (d).