LIMK1/2 in the mPFC Plays a Role in Chronic Stress-Induced Depressive-Like Effects in Mice

BACKGROUND: Depression is one of the most common forms of mental illness and also a leading cause of disability worldwide. Developing novel antidepressant targets beyond the monoaminergic systems is now popular and necessary. LIM kinases, including LIM domain kinase 1 and 2 (LIMK1/2), play a key role in actin and microtubule dynamics through phosphorylating cofilin. Since depression is associated with atrophy of neurons and reduced connectivity, here we speculate that LIMK1/2 may play a role in the pathogenesis of depression. METHODS: In this study, the chronic unpredictable mild stress (CUMS), chronic restraint stress (CRS), and chronic social defeat stress (CSDS) models of depression, various behavioral tests, stereotactic injection, western blotting, and immunofluorescence methods were adopted. RESULTS: CUMS, CRS, and CSDS all significantly enhanced the phosphorylation levels of LIMK1 and LIMK2 in the medial prefrontal cortex (mPFC) but not the hippocampus of mice. Administration of fluoxetine, the most commonly used selective serotonin reuptake inhibitor in clinical practice, fully reversed the effects of CUMS, CRS, and CSDS on LIMK1 and LIMK2 in the mPFC. Moreover, pharmacological inhibition of LIMK1 and LIMK2 in the mPFC by LIMKi 3 infusions notably prevented the pro-depressant effects of CUMS, CRS, and CSDS in mice. CONCLUSIONS: In summary, these results suggest that LIMK1/2 in the mPFC has a role in chronic stress-induced depressive-like effects in mice and could be a novel pharmacological target for developing antidepressants.