The effects of chronic social defeat stress on leptin and its hypothalamic downstream signals. (A) Evaluation of leptin gene expression using real time PCR analysis in the fat tissue (Control, n = 8; Stress, n = 7). (B) Evaluation of leptin peptide expression in the blood plasma (Control, n = 8; Stress, n = 7). (C) Evaluation of the expression and phosphorylation of STAT3 and ERK1/2 in the hypothalamus using western blot analysis. Each band was normalized to actin levels and compared quantitatively using Image J software. (n = 4 / group). *P < 0.05, **P < 0.01 (Student’s t-test); Cont, Control; St, Stress. Data represent the means ± S.E.M.