A morphometric study of the effects of ethanol consumption on lactating mammary glands of rats.

Morphometric procedures were used to quantitate changes induced by ethanol in tissue components of rat mammary gland. Rats were pair-fed ethanol-containing or isocaloric control liquid diets formulated for pregnant or lactating animals, or maintained on regular laboratory chow. Short term animals were pair-fed ethanol or control diets from Day 1 of pregnancy through lactation Days 2 or 10. Long term animals were pair-fed ethanol or control diets for 25 days prior to mating, and then through pregnancy to lactation Days 2 or 10. Point counting was used to determine the volume fractions (vf) of alveolar epithelium, lumen, and connective tissue in the mammary glands. In chow-fed animals the percentage of alveolar epithelium remained constant from late pregnancy through lactation, while the amount of connective tissue decreased and that of alveolar lumen increased. This indicates the sensitivity of this procedure to detect changes in tissue volume fractions during mammary proliferation. No changes from the normal controls were found in any tissue component in short term ethanol or pair-fed animals. At lactation Day 2, long term ethanol-treated animals demonstrated a significant decrease in the percentage of alveolar epithelium and a significant increase in the percentage of total connective tissue as compared to pair-fed and chow-fed control animals. However, by Day 10 of lactation, no changes were found in any of the tissue components in long-term ethanol-fed versus control animals. These results indicate that ethanol consumption can alter mammary gland structure during the early stages of lactation, even when adequate levels of dietary protein are maintained.