Gap junction is essential for the antidepressant effects of fluoxetine

Abstract Objectives Fluoxetine has been used as the first line for the therapy of depression. However, lack of therapeutic efficacy and time lag still limit the application of fluoxetine. Gap junction dysfunction is a potentially novel pathogenic mechanism for depression. To clarify the mechanism underlying these limitations, we investigated whether gap junction was related to the antidepressant effects of fluoxetine. Methods and key findings After chronic unpredictable stress (CUS), animals showed decreases in gap junction intracellular communication (GJIC). Treatment with fluoxetine 10 mg/kg significantly improved GJIC and anhedonia of rats until six days. These results indicated that fluoxetine improved gap junction indirectly. Furthermore, to test the role of gap junction on antidepressant effects of fluoxetine, we blocked gap junction using carbenoxolone (CBX) infusion in the prefrontal cortex. CBX dampened fluoxetine-induced decrease in immobility time of mice in tail suspension test (TST). Conclusions Our study suggested that gap junction dysfunction blocks antidepressant effects of fluoxetine, contributing to understanding the mechanism underlying the time lag of fluoxetine.