Potential between-groups differences in exploratory locomotion were analyzed

using a one-way analysis of variance (ANOVA) to compare exploratory locomotion

between the five groups in Experiment la during their first exposure to social defeat

stress. A 3x6 (group x session) repeated-measures ANOVA (for Experiment la) and a

2xl2 (group x session) repeated-measures ANOVA (for Experiment lb) were used to

examine potential exploratory locomotion differences between groups and across

experimental sessions for the repeatedly stressed groups.

 Potential between-groups differences in plasma ACTH concentrations and in

plasma CORT concentrations were analyzed with one-way ANOVAs in each of

Experiments la and lb. Also, potential between-groups differences in adrenal weights

and in thymus weights were analyzed with one-way ANOVAs in each of Experiments la

and lb. The results were further analyzed using pre-planned Newman-Keuls multiple

comparison tests for all significant ANOVAs.

 Potential between-groups differences in immobility duration scores for the 15-min

Porsolt swim test session in Experiment 2 were analyzed using a one-way ANOVA. The

results were further analyzed using Newman-Keuls multiple comparison tests. The data

were then analyzed in 5-min bins using a 3x3 (group x bin) repeated-measures ANOVA.

The results were further analyzed using Newman-Keuls multiple comparison tests,

making pair-wise comparisons between each stressed group and the control group, for

each bin.

 Inter-observer agreement was assessed for freezing behavior in Experiments la and

lb by comparing total times recorded by each trained observer for each social defeat

session. Inter-observer agreement was also assessed for exploratory locomotion in