Effects of pyridoxine deficiency on the composition of plasma and liver fatty acids in rats fed low and high fat diets.

A study was made of the effect of pyridoxine deficiency on the fatty acids of liver and plasma in rats fed diets containing 1, 10, or 20% fat. Both ad libitum-fed and pair-fed control rats were used. In pyridoxine deficiency, arachidonic acid decreased with a concomitant increase in linoleic acid. Incubation of liver slices with [1-14C]acetate showed no significant alteration of fatty acid synthesis in pyridoxine-deficient rats fed 1 or 10% fat when compared with the ad libitum-fed control rats, but revealed a marked increase in cholesterogenesis compared with either control group. Incubations with [1-14C]linoleate resulted in no differences in the synthesis of arachidonate between the experimental and the ad libitum-fed control rats. Incubations with [5,6,8,9,11,12,14,15-3H]arachidonate showed decreased incorporation of this fatty acid in total liver lipids in pyridoxine-deficient rats compared with ad libitum fed control rats. We concluded that the diminution in arachidonate observed in liver lipids of pyridoxine-deficient rats does not result from a lower conversion of linoleate into arachidonate, but possibly from an increased degradation of this fatty acid.