Desaturation of ¹⁴C Linoleic Acid by the Rat Fetus

Comparison of the Metabolism of Linoleic and Linolenic Acids in the Fetal Rat

“…Our results, unlike those of Pascaud and Strouve-Vallet [8] show significant A6 desa turation in both fetal brain and liver, thus demonstrating the enzymatic capacity to convert linoleic to arachidonic acid. The ac tivities tended to be lower in the liver than the brain.…”

“…The rate of accretion bybrain of arachidonic acid and docosahexa enoic acid is high during the phase of neu ronal multiplication in the rat which occurs early in development before the brain growth spurt: in the rat this is almost com plete by the second day after birth. The liver is believed to play an important role in fatty acid synthesis and in the desaturation and chain elongation of linoleic and a-linolenic acid for other tissues [7], However, Pascaud and Strouve-Vallet [8] suggest that the rate of desaturation of linoleic to arachidonic acid by fetal liver and brain is low in the fetal rat and that the fetal rat may be dependent upon a maternal supply of preformed arachi donic acid. On the other hand, Sanders and Naismith [9] showed that both the fetal rat brain and liver had a high capacity to con vert a-linolenic acid to docosahexaenoic acid, and also reported that linoleic acid was converted to arachidonic acid in fetal brain [10].…”

The metabolism and availability of essential fatty acids in animal and human tissues

“…The 46-desaturation of 18:2n-6 was also detected in fetus brain microsomes in rats (Pascaud and Strouve-Vallet, 1985) and in mouse brain homogenates (Bourre et al, 1990). Recent in vivo experiments (Green and Yavin, 1993) in which labelled 18:3n-3 and 18:2n-6 were intracranially injected into near-term fetal rats, clearly showed that these acids were converted to long-chain polyenoic derivatives in the fetal brain.…”

“…When the precursors are provided, they have to be converted into PUFA by the fetus. In rats, liver microsomes were demonstrated to be capable of transforming 18:2n-6 into 18: 3n-6 by 46-desaturation (Satomi and Matsuda, 1973;Pascaud and Strouve-Vallet, 1985;Ravel et al, 1985). They were also capable of transforming 20:3n-6 into 20:4n-6 by 45-desaturation .…”