Possible involvement of signal transducers and activators of transcription 3 system on depression in the model mice brain.

The aim of this study was to examine gene expression changes in the frontal cortex and hippocampus of animals with different susceptibility to stressful stimuli. Using a learned helplessness (LH) paradigm, mice received moderate current stimulation to induce different extents of LH behavior. Changes in mRNA expression were investigated by microarray and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Comparisons of expression profiles between LH and control or non-learned helplessness (non-LH) animals revealed that the signal transducers and activators of transcription 3 (Stat3)-interacting protein (StIP1) gene is downregulated in LH animals and the suppressor of cytokine signaling 3 (Socs3) gene is up-regulated in non-LH animals. Since both StIP1 and Socs3 regulate the activity of Stat3 gene, these results suggest that Stat3 systems may be involved in the pathogenesis of depressive disorders.