Timeline for experiment. Male and female California mice were run through control handling or social defeat stress. Two weeks later, mice were run through a social interaction test. Tissue samples were collected 1 hour following behavior testing for different cohorts of mice (A). Rgs2 expression in the NAc was confirmed using in-situ hybridization (B). Social defeat stress reduced Rgs2 mRNA in females but not males (C), and Rgs2 mRNA expression levels are positively correlated with social approach behavior (D). Stress reduced RGS2 protein levels in females (E), and these protein levels correlate with social approach (F). *p<0.05 planned comparison vs. female control p<0.05 v. control, ***p<0.001 independent t-test vs. control, † p<0.05 planned comparison v. male control. qPCR group N’s: male/control: 7, male/stress: 7, female/control: 6, female/stress: 8. Western blot group N’s control:4, stress:5.