Effects of dietary protein and EFA deficiency on liver delta 5, delta 6 and delta 9 desaturase activities in the early developing rat.

The influence of protein restriction and EFA deficiency during early development in the rat on the activities of delta 5, delta 6 and delta 9 desaturases was studied. The effect of these diets on body weights and in the fatty acid composition of liver phospholipids was also investigated. The results indicate that the body weights of pups were lowered by feeding the dams both the low-protein and the EFA-deficient diet. The activities of delta 5, delta 6 and delta 9 desaturases were reduced in about 60% by protein deficiency but a rise in the activity of delta 9 desaturase of 362.2% was promoted by feeding the dams the low-fat diet. The fatty acid composition of liver phospholipids indicates that partial deprivation of proteins during early development is associated with a decreased ratio of arachidonate to linoleate. Besides the low-fat group shows in the fatty acid composition of liver phospholipids the typical pattern of EFA deficiency, increased 18:1 and 20:3 omega 9 and decreased 18:2 and 20:4. It is evident from the current investigation that partial deprivation of protein during early development may impair the conversion of linoleate to arachidonate in the rat and that the lack of arachidonic acid observed in the liver cells during protein deficiency would be the consequence of this impairment.