Pure docosahexaenoic acid can improve depression behaviors and affect HPA axis in mice.

OBJECTIVE Aim of this study was to identify whether docosahexaenoic acid (DHA) has a vital antidepressant by hypothalamic-pituitary-adrenal axis (HPA axis) or not. METHODS Mice were divided into 2 groups: control group and DHA dietary group. DHA dietary group was treated with DHA dietary everyday for consecutive 50 days. The forced swimming test and tail suspension test were conducted. Hypothalamic and erythrocyte fatty acids and monoamine neurotransmitters levels in hypothalamus were assayed; corticosterone, adrenocorticotropic hormone and corticotropin-releasing factor in serum, hypothalamus and pituitary were assayed, respectively. RESULTS (1) In the forced swimming test, DHA dietary significantly decreased immobility time, whereas swimming time and climbing time were increased. In tail suspension test, DHA dietary significantly shortened immobility time. (2) DHA dietary increased the ration of n-3/n-6 (polyunsaturated fatty acids) and DHA level in hypothalamic and erythrocyte fatty acids; (3) DHA dietary significantly increased 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and dopamine levels in hypothalamus; (4) DHA dietary significantly decreased serum corticosterone level by 20.23% and serum adrenocorticotropic hormone level by 25.13%; significantly increased serum corticotropin releasing factor level by 21.92%. Besides, DHA dietary decreased arginine vasopressin level by 20.11% in hypothalamus, by 23.76% in pituitary tissues, respectively; (5) DHA dietary decreased corticotropin-releasing factor levels by 30.83% in hypothalamus, by 29.75% in pituitary tissues, respectively. In hypothalamus, DHA dietary decreased significantly adrenocorticotropic hormone level by 19.14%, but insignificantly decreased adrenocorticotropic hormone level in pituitary. CONCLUSIONS DHA shows an antidepressant property. Moreover, DHA has multiple effects on depression including the monoamine neurotransmitter systems, red blood cell membranes and HPA axis.