Maternal lipid metabolism, cytokine profile, and fetal sustainability during gestation: implication of dietary omega-3 polyunsaturated fatty acids

Abstract

The quantity and quality of dietary fats consumed during pregnancy have profound implication on both maternal and fetal health during and after pregnancy. Our laboratory has previously shown that omega (n)-3 polyunsaturated fatty acids (PUFA) regulate offspring lipid and lipoprotein metabolism, and neurotrophin signalling in offspring brain. However, the effects of n-3 PUFA on pregnancy/fetal outcomes are controversial; this is likely due to differences in the amount and/or the source of n-3 PUFA in these studies. My thesis examined the in-utero effects of breeding chow diets, differing in the quantity and quality of dietary fats, on maternal metabolic regulation and pregnancy outcome in C57BL/6 mice. Female mice (7 weeks old) were fed specific diets for 2 weeks before mating and throughout pregnancy; tissues and blood samples were collected before and during gestation at day 6.5, 12.5 and 18.5. My findings revealed that a breeding chow diet containing n-3 PUFA from fish oil maintained maternal metabolic profile to meet fetal lipid requirement during gestation, prevented placental inflammation and sustained more fetuses till late gestation (Chapter 2 and 3). A limitation to this study was that the diets varied in both the quantity (5% vs. 11% w/w), and the quality (providing n-3 PUFA from fish oil at 8% vs. soybean oil at 3% w/w) of fat. I designed my second study using semi-purified diets (containing purified protein, carbohydrate, vitamins and mineral premixes) where the amount of fat was kept consistent (20% w/w), while the amount of n-3 PUFA was varied to give a diet high (9%), low (3%) and very low (1%) in n-3 PUFA from fish oil, respectively. My findings revealed that a maternal diet high in n-3 PUFA prevented dyslipidemia prior to pregnancy and maintained maternal lipid profile required for successful pregnancy. High n-3 PUFA diet also maintained plasma progesterone level during gestation, reduced inflammatory cytokines and sustained higher number of fetuses (Chapter 4). My findings also show that maternal diet high in n-3 PUFA increased the accretion of longer chain n-3 PUFA into fetal brain and regulates neurotrophin signalling as gestation progressed (Chapter 5). Overall, my thesis findings demonstrate the importance of high n-3 PUFA intake during pregnancy.