Maternal high fat diet significantly impacts milk miRNA and mRNA content of lactating mice

Abstract

Neonatal exposure to maternal high fat diet during lactation is associated with development of metabolic syndrome later in life. It is believed that the bioactive components in milk may be responsible for this phenomena. Bioactive components in milk that may be responsible for this are the abundant nucleic acids secreted within exosomes. Exosomal miRNAs circulating throughout body were found to change with nutritional state. We hypothesized that maternal high fat diet affects milk microRNA and mRNA content; and that microRNA and mRNA content in milk impacts offspring development. The objective of this study was to use next generation sequencing to determine the effect of maternal high fat diet on secreted milk transcriptome, specifically miRNA and mRNA expression. For this study, 4‐week old female ICR mice were matched by weight and divided into two treatment groups: control (C) and high fat (HF) diet. HF mice were fed diets with 60% kcal fat and control 10% kcal fat. After 4‐week on diets, mice were mated and were allowed to deliver their pups naturally. On post‐natal day 2 (PND2), litters were normalized to 10 pups and half the pups in each litter were cross‐fostered among treatments. Milk was collected from each dam on PND8, 10 and 12. On PND12 dams were euthanized and blood and milk were collected to measure protein, glucose and lactose. Total RNA was isolated from milk fat fraction of PND10 samples and used for mRNA‐seq and small RNA‐seq. Sequenced reads were aligned to the reference genome using Bowtie and Tophat. Cufflinks was used for transcript assembly, and DeSeq2 was used to analyze differential gene expression. Kilocalorie intake across the 4–weeks pre‐pregnancy was significantly greater (P<0.05) in HF(134.05±25.01kcal) versus C(95.18±8.52kcal) mice, and HF(34.0±4.2g) treatment weighed more than C(27.2±1.7g). However, weight was not different (P>0.05) between HF and C dams on PND2 (HF42.26±3.48g, C38.68±1.79g, respectively) or on PND12 (HF46.7±5.0g, C43.9±4.3g, respectively). Serum and milk percent protein and glucose were not different between C and HF. However, percent lactose was greater (P<0.05) in milk of HF(2.16±0.58%) versus C(1.26±0.41%) dams. Pup weight was significantly greater (P<0.05) in groups that suckled HF(6.68±0.91g) fed dams versus pups fed by C(5.06±0.68g) dams, regardless of biological dams. Differential abundance of a subset of miRNA and mRNA molecules were found in milk of HF versus C dams. These results show that maternal HF diet effects secreted milk transcriptome. If these nucleic acids maintain biological activity they have the potential to affect offspring development.Support or Funding InformationAgSeed‐Agricultural Research and Extension Leading to Economic Development in Indiana Agriculture and Rural Communities