On the optimal ratio of ARA/DHA intake for early brain development and function

Previously, we investigated the role of each PUFAs using artificially reared delta-6 desaturase knockout (D6D KO) mice without the influence of Dam’s milk and reported that ARA is necessary for body growth and DHA is necessary for brain function acquisition during the neonatal period.  In order to better define the interaction between ARA and DHA, we investigated the appropriate balance of ARA and DHA required for neurogenesis and brain function acquisition using a similar test system.   In various experimental groups, ARA and/or DHA were added at different ratios to basal formula containing ALA and LA (basal formula), and compared with WT type.  Weight gain during artificial rearing was significantly worse in KO-Cont compared to WT-Cont, and adding DHA alone also showed a tendency for weight loss.  However, all groups fed formula containing ARA were similar to WT-Cont.  In the task acquisition of the water maze test., As previously established, brain function was reduced in KO-Cont, but the group fed formula containing DHA showed performance close to WT-Cont.  In the reproduction of task memory, the ARA+DHA group showed slightly better performance than the 2ARA+DHA group.   However, the 2ARA+DHA group was the one that was most similar to WT-Cont in terms of PUFA composition in the hippocampus.  In addition, the degree of optic nerve formation after eyelid opening during artificial rearing was evaluated.  Both the ARA+DHA and 2ARA+DHA groups showed significant improvements in the myelin sheath thickness and G ratio of the myelinated nerve compared to KO-Cont, and were similar to WT-Cont.   These results suggest that an interaction between ARA and DHA is required for brain formation and function expression, and that the optimal ARA/DHA ratio is between 1 and 2.