Antidepressant-like Effects of an Aqueous Extract of Lavender (Lavandula angustifolia Mill.) in Rats

The purpose of the present study was to examine the antidepressant-like effects of an aqueous extract of lavender (LAE) using the forced swimming test (FST), the most widely used animal model of depression. LAE was orally administered to rats three times, i.e., 24, 5, and 1 h prior to the FST. The administration of LAE (3428 mg/kg body weight) showed a significant reduction of the immobility time in the FST, the effect of which was comparable to that of the synthetic antidepressant, imipramine (30 mg/kg). In addition, the same dose of LAE did not change the locomotor activity in the open field test. These results suggest that LAE might have antidepressant-like effects that are independent of motor stimulation. Furthermore, the active ingredients of LAE were suggested to be non-volatile constituents, because linalool, the main aroma constituent of lavender, was completely removed during the preparation of LAE. Possible contribution of rosmarinic acid and that of apigenin glycosides to the antidepressant-like effects of LAE were discussed on the basis of their content in LAE.