The antidepressant activities of hispidol and decursin (both potent monoamine oxidase A (MAO-A) inhibitors) were evaluated using the forced swimming test (FST) and the tail suspension test (TST) in mice, and thereafter, levels of neurotransmitter monoamines and metabolites in brain tissues were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hispidol (15 mg/kg) caused less or comparable immobility than fluoxetine (15 mg/kg; the positive control) in immobility time, as determined by FST (9.6 vs 32.0 s) and TST (53.1 vs 48.7 s), respectively, and its effects were dose-dependent and significant. Decursin (15 mg/kg) also produced immobility comparable to that of fluoxetine as determined by FST (47.0 vs 43.4 s) and TST (55.6 vs 63.4 s), and its effects were also dose-dependent and significant. LC-MS/MS analysis after FST showed that hispidol (15 mg/kg) greatly increased dopamine (DA) and serotonin levels dose-dependently in brain tissues as compared with the positive control. Decursin (15 mg/kg) dose-dependently increased DA level after TST. Slight changes in norepinephrine and 3,4-dihydroxyphenylacetic acid levels were observed after FST and TST in hispidol- or decursin-treated animals. It was observed that hispidol and decursin were effective and comparable to fluoxetine in immobility tests. These immobility and monoamine level results suggest that hispidol and decursin are potential antidepressant agents for the treatment of depression, and that they act mainly through serotonergic and/or dopaminergic systems.
Keywords: Antidepressant-like activity; Decursin; Hispidol; neurotransmitter monoamines.