Emotion-Based cognition in mice is differentially influenced by dose and chemical form of dietary docosahexaenoic acid

Authors: Laugero, Kevin; Adkins, Yuriko; Kelley, Darshan; Mackey, Bruce

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2017
Publication Date: 9/8/2017
Citation: Laugero, K.D., Adkins, Y.C., Kelley, D.S., Mackey, B.E. 2017. Emotion-Based cognition in mice is differentially influenced by dose and chemical form of dietary docosahexaenoic acid. Nutrients. 9(9):993. https://doi.org/10.3390/nu9090993.
DOI: https://doi.org/10.3390/nu9090993

Interpretive Summary: Dietary omega-3 fatty acids, such as docosahexaenoic acid (DHA), may have important effects on the brain. Previous studies suggest that deficiencies in omega-3 fatty acids in the diet and lower concentrations of these fats in the brain may increase risk for impaired learning and memory, as well as disorders of mood and emotion. Furthermore, consumption of DHA and foods rich in DHA may facilitate the protection of these important neurological functions and prevent diseases like Alzheimer’s and depression. However, there have been some inconsistencies across research studies, with some showing positive effects and others no effects of DHA and omega-3 consumption. One reason for these inconsistencies may be the type and source of DHA. For example, DHA derived from triglyceride (TG) and DHA derived from phospholipids (PL) may confer different effects. We compared in mice effects of consuming PL and TG derived DHA on learning and memory, as well as anxiety. Our findings suggest that consuming comparatively smaller amounts of DHA derived from PL may confer enhanced efficacy, particularly on fear based learning behavior, and these effects may come with less negative side effects than those promoted by higher doses of the fatty acid.

Technical Abstract: Docosahexaenoic acid (DHA) is a major constituent, and primary omega-3 fatty acid, in the brain. Evidence suggests that DHA consumption may promote cognitive functioning and prevent cognitive decline, and these effects may be particularly relevant in the context of fear or stress. However, the potency and medicinal utility of dietary DHA may depend on the source of DHA (e.g., phospholipid; PL vs. triglyceride; TG). In this study, we compared in mice effects of consuming PL and TG derived DHA on associative, avoidance (fear) based learning and memory. Diets consisted of either no DHA or 1, 2, and 4% PL or TG DHA. After 4 wks on the test diets (n=12/group), we used the 3 day passive avoidance (PA) and elevated plus maze (EPM) to examine fear and fear associated learning and memory. We found a significant (P<0.05) diet by time interaction in the PA and EPM. Compared to the control and the 1% TG-DHA group, mice consuming the diet supplemented with 1% PL-DHA displayed a significantly greater latency by test day 2 in the 3 day PA. No differences in latency between any of the groups were observed during trials 1 and 3. Mice consuming the 2% diet spent significantly more time frequenting the open arms during the first minute, but not last 4 minutes, of the test. Compared to all other groups, mice fed 4% DHA displayed a metabolic profile consistent with inflammation; increased spleen, liver, and visceral fat weight. Consuming comparatively smaller amounts of DHA derived from PL may confer enhanced efficacy, particularly on fear based learning behavior, and these effects may come with less negative side effects.