[Influence of a fat-free diet on the content and synthesis of arachidonic acid in the feto-placental unit of the rat].

In rats receiving a fat-free food throughout the period of pregnancy, the individual fatty acids of total lipids from placenta, total fetus, maternal and fetal serum were determined quantitatively on day 21/22 of pregnancy. Also, the incorporation of 14C-acetate in vitro into placental fatty acids, divided by the number of double bonds, was measured and the rate of synthesis calculated therefrom. The fat-free diet caused a drastic fall of linoleic acid concentration in maternal serum and all fetal compartments. On the contrary, the amount of arachidonic acid remained almost unchanged in fetal serum and total fetus, and even slightly increased in placenta. In the maternal serum, too, the arachidonic acid concentration remained constant under fat-free diet. The observed concentration changes of single fatty acids in the maternal serum are reflected in all fetal compartments and led to a rise in total fatty acids in all sera and tissues studied. The height of rise decreased in the order: maternal serum less than placenta less than fetal serum less than total fetus. The rate of synthesis for arachidonic acid in placenta was on day 21/22 of pregnancy 0.3 (controls) and 0.5 (fat-free diet) micrometer/100 g placenta and hour, being able to cover the placenta's own need to less than one-third. The results suggest that the protection of the feto-placental unit against arachidonic acid deficiency under fat-free diet of the mother is provided mainly by a constant supply of maternal unit with arachidonic acid under normal conditions has to be ensured essentially by the mother.