Fig. 1.

Social defeat stress induces a depression-like behavioral response in adolescent C57BL/6 male mice. (a) Timeline of the experimental procedures. Adolescent (postnatal day [PD]) 35 mice were exposed to 10 days of social defeat stress (i.e., PD35-44). Twenty-four h later (PD45), mice were tested on either the social interaction or tail suspension test. (b) Defeated mice spent less time in the interaction zone in the presence, versus the absence, of a social target (^∗p < 0.05, within group comparison), which was significantly less than that of control mice during the target present condition (^#p < 0.05, between group comparison). (c) This reduction of social behavior was evident when assessing time in the corner zones, in which defeated mice spent significantly more time in the corners regardless of whether the social target was present (^#p < 0.05, between group comparison) or absent (^∗p < 0.05, within group comparison). (d) No differences in total distance traveled between control and defeated mice were observed during the first 2.5 min of the social interaction test (target absent condition). (e) Defeated mice spent more time (sec) immobile in the tail suspension test, when compared to control mice (^∗p < 0.05). Data are presented as mean + SEM.