Antidepressant and anxiolytic-like behavioral effects of erucamide, a bioactive fatty acid amide, involving the hypothalamus-pituitary-adrenal axis in mice.

Erucamide (Era) is a bioactive fatty acid amide, which is similar to the classical endocannabinoid analogue oleoylethanolamide (OEA). In the present study, we hypothesized that Era may regulate the central nervous system and may have the potential to antagonize depression and anxiety. Therefore, we investigated the antidepressant and anxiolytic effects of Era in animal models in comparison with fluoxetine (Fxt). Fifty mice were randomly divided into 5 groups, and treated with a vehicle (0.3% methyl cellulose, 20mL/kg, p.o.), Era (5, 10, 20mg/kg, p.o.), or Fxt (20mg/kg, p.o.) for 7days. Immobility was used to evaluate depressive-like behavior in the forced swimming test (FST) and tail suspension test (TST). Animal activity and exploratory behavior as well as anxiety-like behaviors were measured in open field test (OFT) and elevated plus-maze test (EPMT) in mice. Additionally, serum adrenocorticotrophic hormone (ACTH) and corticosterone (CORT) levels were determined using the ELISA method, and the total anti-oxidative capacity (T-AOC) was detected by ultraviolet spectrophotometry. Our data showed that Era (5, 10, or 20mg/kg) induced a significant reduction in mouse immobility time in the TST and FST compared to the normal control group (vehicle group). The positive control, Fxt (20mg/kg group), also induced a significant change in immobility time in the TST and FST compared to the control (vehicle) group. In the OFT, compared with the control group, Fxt (20mg/kg) and Era (5, 10, or 20mg/kg) did not significantly change the locomotive activity (locomotive time, immobility time, or locomotive distance) in mice, but Fxt (20mg/kg) and Era (10, or 20mg/kg) significantly increased the percentage of time spent and squares visited in the OFT central area. In regards to the EPMT, the data showed that Fxt (20mg/kg) and Era (10, 20mg/kg) significantly increased the ratio of time spent and entries in open arms, but did not significantly change the total locomotive distance (including open arms and closed arms) compared to the control group. Biochemical tests found that after 7days of drug treatment, compared with the control group, ACTH and CORT serum levels in mice were significantly decreased, although T-AOC levels did not significantly change. In conclusion, Era (dose range of 5-20mg/kg) administered orally may alleviate depression- and anxiety-like behaviors in mice, and the antidepressant and anti-anxiety effects of Era may be related to the regulation of the hypothalamus-pituitary-adrenal axis (HPA).