[Effect of alloxan diabetes on the biosynthesis of unsaturated fatty acids from linoleic and arachidonic acids in rat liver and testis (author's transl)].

The effect of alloxan diabetes on the desaturating, elongating, and elongating-desaturating activity of the microsomes of rat liver and testis was studied. Linoleic and arachidonic acids were tested. It was found that in both liver and testis linoleic acid was desaturated to gamma-linolenic acid (18:3) when the conditions were exclusively desaturating. Diabetes deceased the 6-desaturase activity of both tissues. In elongating and desaturating conditions linoleic acid was converted to 18:3, 20:2, 20:3, 20:4, 22:2, 22:5 and 24:2 in both tissues. Alloxan diabetes decreased the activity of the reactions controlled by the 6-desaturase reducing the conversion to 18:3 in both tissues and to 20:4 only in liver. The elongating reactions were not significantly modified. When only elongating conditions were tested, either liver or testis synthetized only 20:2, 22:2 and 24:2 from linoleic acid and 22:4 from arachidonic acid. The elongating activity for both fatty acids was not decreased by diabetes. Therefore, it was proved that alloxan diabetes interferes with the metabolism of linoleic acid in both tissues, decreasing only the desaturation reaction, whereas the elongation of the fatty acid is not reduced.