D-004, a lipid extract from royal palm fruit, exhibits antidepressant effects in the forced swim test and the tail suspension test in mice

D-004, a lipid extract of Roystonea regia fruits, has been shown to reduce Testosterone, but not dihydrotestosterone-induced prostate hyperplasia in rodents. Inhibition of prostate 5α-reductase seems to explain these effects of D-004. Finasteride, an inhibitor of 5α-reductase used to treat benign prostate hyperplasia (BPH), has been shown to produce drug-induced depression and to increase mouse immobility in the forced swim test (FST). In this study, therefore, we investigated the effect of D-004 on the immobility in the FST and the tail suspension test (TST) in mice. Also, its effects on other behavioural tests (grip strength, open field activity and rotarod test) were investigated. Mice were randomized into five groups: three groups orally treated with D-004 (250, 500 and 1000 mg/kg) or vehicle (control group), and a fifth group that received intraperitoneally (IP) imipramine 20 mg/kg for 30 days. In the FST, D-004 (250, 500 and 1000 mg/kg) produced a statistically significant reduction in immobility (51, 58, and 65%, respectively, versus the control group), whereas imipramine reduced FST immobility by 69%. In the TST, D-004 (250 and 500 mg/kg) significantly, but modestly (21%) reduced the immobility versus the control group, although less than imipramine (50%). The lowest dose of D-004 (50 mg/kg), however, was ineffective. D-004 did not alter the results of other behavioural tests. In conclusion, D-004 (250-1000 mg/kg) administered orally for 30 days reduced the immobility in the FST and the TST in mice, and had no effect on other behavioural tests in mice.