Immunostaining for phosphorylated ERK in female (A) and male (C) NAc.

<p>Males had more pERK positive cells than females in the NAc shell (B) but not in the NAc core (D). † Mann-Whitney sex difference in controls p<0.05. All data are mean±s.e. Anterior commissure, ac. Scale bars = 100 µm.</p

Representation of areas quantified using microscopic analyses in experiment 1.

<p>Reproduced from Paxinos & Franklin (2003), with permission from Academic Press. Abbreviations: Nucleus accumbens (NAc), dorsomedial bed nucleus of the stria terminalis (dmBNST), dorsolateral bed nucleus of the stria terminalis (dlBNST), ventral bed nucleus of the stria terminalis (vBNST), paraventricular nucleus (PVN), basolateral amygdala (BLA), central nucleus of the amygdala (CEA), dorsomedial amygdala (dMEA), dorsoventral amygdala (vMEA).</p

Effects of social defeat in the habituation-dishabituation test.

<p>Social defeat reduced time spent investigating a glass slide with a water droplet (trials 1–3) in both males (A) and females (B). In males defeat reduced, but did not eliminate investigation of novel male odors (trial 4 and 7). Females exposed to defeat did not show a significant increase in investigation time of novel female odors (trials 4 and 7). †, †† Mann-Whitney effect of stress p<0.05 and p<0.01 respectively. *, ** Wilcoxon test versus previous trial (trial 3 vs. 4 or 6 vs. 7) p<0.05, p<0.01 respectively. All data are mean±s.e.</p

Cell counts for pCREB and pERK positive cells immediately after social interaction tests.

†<p>sex difference within treatment group p<0.05 Mann-Whitney test.</p><p>*effect of stress within sex p<0.05 Mann-Whitney test.</p><p>All data are mean±s.e.</p

Immunostaining for phosphorylated CREB in female (A, B, C) and male (D,E, F) California mice after social interaction tests.

<p>Mice were exposed to three control or social defeat episodes. Social defeat increased the number of pCREB positive cells in females but not males in the NAc shell (C) and core (F). Control males generally had higher pCREB cell counts than control females. † Mann-Whitney sex difference in controls p<0.05, *, **, Mann-Whitney effect of stress p<0.05, p<0.01 respectively. All data are mean±s.e. Anterior commissure, ac. Scale bars = 100 µm.</p

Social interaction behavior in male and female California mice four weeks after social defeat.

<p>In the apparatus used for testing (A), the interaction zone is indicated by a blue box and the corner zones indicated by red boxes. There were no significant differences when mice were tested with an empty cage (B). Females, but not males exposed to social defeat showed reduced social interaction behavior with a novel mouse (C). Immediately after the social interaction test mice were euthanized and vaginal lavage was conducted to determine estrous cycle stage. Social defeat reduced social interaction time at different stages of the estrous cycle (D). Corticosterone levels measured immediately after social interaction testing were higher in females compared to males (E). * main effect of sex p<0.05, ** planned comparison control group versus stress group p<0.01. *** planned comparison control group versus stress group p<0.01. All data are mean±s.e.</p

Effects of social defeat on corticosterone.

<p>Social defeat increased baseline corticosterone in males but not females during both the inactive (A) and active (B) phases. *, ** Mann-Whitney effect of stress p<0.05, p<0.01 respectively. † Mann-Whitney sex difference in controls p<0.05. All data are mean±s.e.</p

Effects of social defeat on time spent in the center (A) and total activity (B) in the open field test and time spent on the light side of the light-dark box test (C).

<p>* main effect of sex p<0.05. All data are mean±s.e.</p

Behavioral data from social interaction tests with empty cage and a novel mouse (target).

<p>All times in sec, all distances in m.</p><p>+ p<0.05,</p><p>++ p<0.01,</p><p>+++ p<0.001 paired t-test with empty cage trial (within group).</p>**<p>p<0.01, planned comparison control vs. stress following significant sex x stress interaction. All data are mean±s.e.</p

Correlation between pCREB positive cells in NAc shell and interaction time with a novel target mouse.

<p>Filled circles (control males), open circles (stressed males), filled triangles (control females), open triangles (stressed females). Spearman ρ = −0.37, p<0.05.</p