Umbelliferone modulates depression-like symptoms by altering monoamines in a rat post-traumatic stress disorder model. 
Post-traumatic stress disorder (PTSD) is a debilitating psychological disease that is triggered by traumatic events.  It is known to cause various complications, including anxiety and depression.  Umbelliferone (UMB) is a natural product of the coumarin family.  This substance has been reported to exert antioxidant, anti-inflammatory, neuroprotective, and other biological effects.  We used the open field test (OFT) and the forced swimming test (FST) to examine the effects of UMB on depression-like symptoms in rats after exposure to a single prolonged stress (SPS), which led to dysregulated activation of the serotonergic system.  Male rats were given UMB (20, 40, or 60 mg/kg, intraperitoneal injection) once daily for 14 days after exposure to an SPS.  Daily UMB administration significantly improved depression-like behaviors on the FST, increased the number of lines crossed in the central zone of the OFT, and reduced freezing behavior in both contextual and cued fear conditioning.  UMB treatment attenuated the SPS-induced decrease in serotonin (5-HT) concentrations in the hippocampus and amygdala.  The increased 5-HT concentration during UMB treatment was partially due to a decrease in the ratio of 5-hydroxyindoleacetic acid/5-HT in the hippocampus of rats with PTSD.  According to our results, UMB has an antidepressant effect in rats exposed to an SPS, suggesting that this natural product of the coumarin family can be used to effectively treat PTSD.