Effect of chronic administration of ostruthin on depression-like behavior in chronically stressed mice.

We have previously shown that a single dose of a TREK-1 channel activator, ostruthin, exhibited antidepressant and anxiolytic effects in acute behavioral test models in mice. To assess the potential clinical application, it is essential to evaluate the effects of long-term administration of ostruthin in a chronically stressed mouse model, which is considered to be similar to the clinical condition of major depression in humans. Here, we tested the effects of a single and a 7-day administration of ostruthin on mice that were subjected to chronic unpredictable mild stress (CUMS). A single administration of ostruthin showed antidepressive effects in the tail suspension and forced swim tests of CUMS-treated mice. Unexpectedly, the 7-day administration exhibited only insignificant antidepressive and anxiolytic effects. The 7-day regimen did not affect food intake or body-weight gain, suggesting the absence of apparent cytotoxicity. The mice receiving the 7-day administration had significantly lower blood concentrations of ostruthin compared to those receiving a single dose, suggesting an upregulation of drug-metabolizing activities. These findings suggest that there is a need for stable TREK-1 channel activators that are not affected by drug metabolism.