The Effect of Maternal Dietary Fat Content Andn-6:N-3 Ratio on Offspring Growth and Hepatic Gene Expression in the Rat

Omega-6 fatty acids have been shown to exert pro-adipogenic effects whereas omega-3 fatty acids work in opposition. Increasing intakes of LA (linoleic acid; omega-6) vs ALA (alpha-linolenic acid; omega-3) in Western diets has led to the hypothesis that consumption of this diet during pregnancy may be contributing to adverse offspring health. This study investigated the effects of feeding a maternal dietary LA:ALA ratio similar to that of the Western diet (9:1) compared to a proposed 'ideal' ratio (~1:1.5), at two total fat levels (18% vs 36% fat w/w), on growth and lipogenic gene expression in the offspring. Female Wistar rats were assigned to one of the four experimental groups throughout gestation and lactation. Offspring were culled at 1 and 2 weeks of age for sample collection. Offspring of dams consuming a -36% fat diet were ~20% lighter than those exposed to a 18% fat diet (P<0.001). Male, but not female, liver weight at 1 week was ~13% heavier, and had increased glycogen (P<0.05), in offspring exposed to high LA (P<0.01). Hepatic expression of lipogenic genes suggested an increase in lipogenesis in male offspring exposed to a 36% fat maternal diet and in female offspring exposed to a low LA diet, via increases in the expression of Fasn and Srebf1. Sexually dimorphic responses to altered maternal diet appeared to persist until two weeks-of-age. In conclusion, whilst maternal total fat content predominantly affected offspring growth, fatty acid ratio and total fat content had sexually dimorphic effects on offspring liver weight and composition.