Impact of exposure to diesel exhaust during pregnancy on mammary gland development and milk composition in the rabbit

PLoS One. 2019 Feb 14;14(2):e0212132. doi: 10.1371/journal.pone.0212132. eCollection 2019.

Abstract

Exposure to fine-particulate air pollution is a major global health concern because it is associated with reduced birth weight and an increased risk of cardiovascular disease. Here we have investigated the potential for exposure to diesel exhaust during pregnancy to influence mammary gland development and milk composition. Female rabbits were therefore exposed by nose-only inhalation to either diluted diesel exhaust fumes (1 mg/m3) or clean air for 2h/day, 5 days/week, from the 3rd to the 27th days of pregnancy. On Day 28 of pregnancy, mammary glands were collected from twelve females (six controls and six diesel-exposed) and assessed for morphological and functional alterations. Milk samples were collected from eighteen dams (nine controls and nine diesel-exposed) during early (days 2 to 4) and established (days 13 to 16) lactation to verify the composition of fatty acids and major proteins and leptin levels. The mammary alveolar lumina contained numerous fat globules, and stearoyl CoA reductase expression was higher in mammary epithelia from diesel exhaust-exposed rabbits, which together suggested increased mammary lipid biosynthesis. Gas chromatography analysis of the composition of milk fatty acids revealed a sharp rise in the total fatty acid content, mainly due to monounsaturated fatty acids. Liquid chromatography-mass spectrometry analysis of milk samples enabled identification and quantification of the main rabbit milk proteins and their main phosphorylated isoforms, and revealed important changes to individual casein and whey protein contents and to their most phosphorylated isoforms during early lactation. Taken together, these findings suggest that repeated daily exposure to diesel exhaust fumes during pregnancy at urban pollution levels can influence lipid metabolism in the mammary gland and the lipid and protein composition of milk. As milk may contribute to metabolic programming, such alterations affecting milk composition should be taken into account from a public health perspective.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / drug effects
  • Adipose Tissue / metabolism
  • Animals
  • Fatty Acids / metabolism
  • Female
  • Gene Expression Regulation, Developmental / drug effects
  • Leptin / metabolism
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / genetics
  • Mammary Glands, Animal / cytology
  • Mammary Glands, Animal / drug effects*
  • Mammary Glands, Animal / growth & development*
  • Milk / chemistry*
  • Milk / drug effects*
  • Milk / metabolism
  • Milk Proteins / metabolism
  • Pregnancy
  • Rabbits
  • Vehicle Emissions / toxicity*

Substances

  • Fatty Acids
  • Leptin
  • Milk Proteins
  • Vehicle Emissions

Grant support

The ERC program e-DOHAD and the Agence Nationale de la Recherche (ANR, France) project EPPAP (PI: Dr. Pascale Chavatte-Palmer) funded the animal experiments. EPPAP also covered the costs of mammary gland analyses. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.