The hippocampal Salt-Inducible Kinase 2-CREB-Regulated Transcription Co-activator 1 system mediates the antidepressant actions of paroxetine in mice

The hippocampal salt-inducible kinase 2 (SIK2)-CREB-regulated transcription co-activator 1 (CRTC1) system has been demonstrated to participate in not only the pathogenesis of depression but also the antidepressant mechanisms of several antidepressant medications including fluoxetine, paroxetine, and mirtazapine. Like fluoxetine, paroxetine is also a widely used selective serotonin (5-HT) reuptake inhibitor (SSRI). Recent studies have indicated that paroxetine also modulates several pharmacological targets other than the 5-HT system. Here, we speculate that paroxetine regulates the hippocampal SIK2-CRTC1 system. Chronic stress models of depression, various behavioral tests, western blotting, co-immunoprecipitation, quantitative real-time reverse transcription PCR, and genetic knockdown were used together in the present study. Our results show that the antidepressant actions of paroxetine in mice models of depression were accompanied by its preventing effects against chronic stress on hippocampal SIK2, CRTC1, and CRTC1-CREB binding. In contrast, genetic knockdown of hippocampal CRTC1 notably abrogated the antidepressant effects of paroxetine in mice. In summary, regulating hippocampal SIK2 and CRTC1 participates in the antidepressant mechanism of paroxetine, extending the knowledge of its pharmacological targets.