Peripheral interleukin-6 promotes resilience versus susceptibility to inescapable electric stress

Objective: Accumulating evidences suggest that pro-inflammatory cytokines such as interleukin-6 (IL-6) play a role in the pathophysiology of depression. In the learned helplessness (LH) paradigm, similar to 35% rats are resilient to inescapable stress. Methods: Levels of IL-6 in the serum and medial prefrontal cortex (mPFC) of LH rats (susceptible) and non-LH rats (resilience) were measured using enzyme-linked immunosorbent assay and western blot analysis, respectively. Results: Serum levels of IL-6 in the LH rats were significantly higher than those of control and non-LH rats. In contrast, tissue levels of IL-6 in the mPFC were not different among three groups. Conclusion: The results suggest that peripheral IL-6 may contribute to resilience versus susceptibility to inescapable stress.