Developmental changes in rat brain membrane lipids and fatty acids: the preferential prenatal accumulation of docosahexaenoic acid

Information on the prenatal accumulation of rat brain membrane lipids is sc arce. In this study we investigated in detail the fatty acid (FA) compositi on of the rat brain, on each day from embryonic day 12 (E12) up to birth, a nd on 8 time points during the first 16 days of postnatal life, and correla ted the FA changes with well-described events of neurogenesis and synaptoge nesis, Between E14 and E17, there was a steep increase in the concentration of all the FAs: 16:0 increased by 136%, 18:0 by 139%, 18:1 by 92%, 20:4n-6 by 98%, 22:4n-6 by 116%, 22:5n-6 by 220%, and 22:6n-3 by 98%. After this p eriod and up to birth, the concentration of the FAs plateaued, except that of 22:6n-3, which accumulated further, reaching an additional increase of 7 5%. After birth, except 22:5n-6, all FAs steadily increased at various rate s. Estimation of the FA/PL molar ratios showed that prenatally the ratios o f all the FAs either decreased or remained constant, but that of 22:6n-3 in creased more than 2-fold; post-natally the ratios remained constant, with t he exception of 22:4n-6 and 22:5n-6, which decreased. In conclusion, prenat al accumulation of brain fatty acids parallels important events in neurogen esis. 22:6n-3 is exceptional inasmuch in its steep accumulation occurs just prior to synaptogenesis.