Maternal diet high in Omega-3 fatty acids upregulate genes involved in neurotrophin signalling in fetal brain during pregnancy in C57BL/6 mice

Neurotrophins play a critical role in the development, maintenance, and proper function of the brain. We investigated the effects of maternal diet high in omega (n)-3 polyunsaturated fatty acids (PUFA) on fatty acids composition and the gene expression of neurotrophins in fetal brain at different gestation stages. Female C57BL/6 mice (7-weeks old, n = 8/group) were fed a diet containing high, low or very low n-3 PUFA (9, 3 or 1% w/w, respectively), with an n-6:n-3 PUFA of 5:1, 20:1 and 40:1, respectively, for two weeks before mating and throughout pregnancy. Animals were sacrificed during pregnancy at gestation day 12.5 and 18.5 to determine placental and fetal-brain fatty acids composition. The gene expressions of endothelial lipase (EL) and plasma membrane fatty acid-binding protein (FABPpm) were measured in the placenta, while major facilitator superfamily domain-containing 2a (Mfsd2a), brain-derived neurotrophic factor (BDNF), tropomyosin-receptor kinase (TrK)-B, and cAMP response element-binding protein (CREB) were measured in fetal-brain, using qPCR. The protein expression of phosphorylated CREB (pCREB) was determined using ELISA. The high n-3 PUFA diet increased the mRNA expression of EL, FABPpm, and Mfsd2a at both gestation days, compared to other groups. Docosahexaenoic acid (DHA) and total n-3 PUFA were significantly higher in the high n-3 PUFA group, compared to the other groups at both gestation days. The high n-3 PUFA diet also increased the mRNA expressions of BDNF, TrKB and CREB, as well as the protein concentration of pCREB as gestation progressed, compared to the other groups. Our findings show for the first time that maternal diet high in n-3 PUFA increased the mRNA expression of Mfsd2a, which correlated with an increase in DHA accretion in the fetal-brain. A diet high in n-3 PUFA increased neurotrophin signalling in fetal-brain as gestation progressed, demonstrating the importance of n-3 PUFA during brain development.