Recent reports have implicated microbiota-gut-brain regulation in the neuropathogenesis of bipolar depression by modulating TRANK1 expression [36], suggesting that Trank1 may be another potential target for future study to examine the functional links between the dysregulated AP1AR-DT identified in the peripheral system and the neuropathogenesis of bipolar disorder. This evidence concerns the gene TRANK1 and bipolar disorder.