The Study on Role of Docosahexaenoic Acid for the n-3 Fatty Acid Deficiency in Mice

Abstract

The n-3 fatty acids, especially, docosahexaenoic acid (DHA) cannot be synthesized in mammals, although there are nutritionally essential polyunsaturated fatty acids. Therefore, it is necessary to take some food containing DHA or its precursor. Many animal studies have reported that the dietary n-3 fatty acid deprivation produces a loss of brain function. Recently, several reports have been presented concerning various mental functions including mood disorders under the n-3 fatty acid deficiency. In this study, the focus is on the decrease of the emotional function under the n-3 fatty acid deficiency and the incorporation of DHA into the fetal brain in n-3 fatty acid deficiency pregnant mice. Using the novelty suppressed feeding paradigm, n-3 fatty acid deficient or adequate mice were measured for the anxiety level under two kinds of breeding conditions (group housed or isolation stress). The n-3 fatty acid deficient mice indicated an increase of anxiety and were enhanced anxiety level by the chronic mild stress of social isolation. On the other hand, the incorporation of DHA into the fetal brain in the n-3 fatty acid deficient pregnant mice after switching to the n-3 fatty acid adequate diet was measured. Alpha-linolenic acid in the n-3 fatty acid adequate diet was supplied into fetus by the mother via the placenta after being metabolized to DHA. A nutritional intervention with n-3 fatty acid adequate diet can nearly but incompletely rescue the mouse fetal DHA deficiency, if begun at the time of conception but that the third trimester is too late.