Mammary Gland Structure and Functional Changes in Mouse Model of Chronic Gestational Alcohol Exposure

Abstract

Little research has been done regarding the effects of moderate ethanol exposure (PAE) on mammary gland development and subsequent milk production during lactation. Pregnant C57/Bl6J females were exposed to 3 g/kg alcohol (EtOH) from gestational day (GD) 12.5 to 17.5 in two half doses, two hours apart using isocaloric maltodextrin (MD) as controls. Most EtOH litters did not have milkspots at lactation day two (L2) suggesting that dam lactation or pup nursing was negatively affected after PAE. Mammary glands were collected from subsequent EtOH dams on L2 and were found to weigh less than MD dams (p<0.05). Carmine staining of mammary glands revealed decreased density of ducts and tubules compared with MD mammary glands preliminarily suggesting abnormal or delayed maturation. Further investigation using weigh‐suckle‐weigh methods discovered that milk letdown during a bout of nursing was significantly decreased in EtOH compared with MD litters at L2 (p<0.05). Mammary glands, liver, and adipose tissue of dams were collected for histology, fatty acid composition and retinoic acid stores, as numerous studies document the adverse effects of alcohol on vitamin A and fatty acid metabolism. Milk was collected from these dams in order to determine composition, particularly fatty acid, protein, and lactose. H & E staining in EtOH mammary glands revealed collapsed lobules and immature ducts, as well as decreased adipose stores shown by Oil Red O staining. However, retinoic acid and fatty acid composition were unaltered between groups. Although total protein concentration did not differ in the milk, free fatty acid composition was significantly altered (p<0.05), suggesting that PAE interferes with de novo synthesis of fatty acids into milk. Further studies will characterize that pathway after PAE as well as determine the lactose content and protein profile in milk and mammary gland. Hormonal changes will also be investigated because PAE has been shown to affect prolactin and progesterone which are essential for initiation of lactation. These studies are essential for determining how lactation after PAE affects nutrition and growth in populations where it is common for the affected child to remain with the birth mother.Support or Funding InformationAA11085, AA22999, T32DK007665