MARGINAL ZINC DEFICIENCY DISRUPTS MAMMARY GLAND MORPHOLOGY AND COMPROMISES MILK SECRETION
Open Access
- Author:
- Dempsey, Colleen
- Area of Honors:
- Nutritional Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Shannon Leanne Kelleher, Thesis Supervisor
Shannon Leanne Kelleher, Thesis Supervisor
Rebecca L Corwin, Thesis Honors Advisor - Keywords:
- zinc
lactation
zinc deficiency
mammary gland
milk secretion
macronutrient concentration - Abstract:
- Zinc (Zn) is the second most abundant trace element in the body and is present in all cells. As an essential component of over 300 enzymes and proteins, Zn is involved in numerous biological processes at both the physiological and molecular levels. It is estimated that 82% of pregnant and lactating women worldwide are at risk of developing Zn deficiency due to inadequate Zn intake from the diet. Few studies have addressed the maternal factors that may contribute to marginal Zn deficiency in the infant, which may include Zn concentration in the mammary gland and milk, mammary gland structure, and milk secretion. We used a mouse model and fed them a diet adequate in Zn (ZA: 25 mg Zn/kg) or a diet reduced in Zn (ZD: 12 mg Zn/kg) for thirty days prior to conception. Our findings indicate that mammary gland morphology was severely compromised by marginal Zn deficiency which resulted from apoptosis in the mammary glands of ZD mice, despite the fact that total Zn content of the mammary gland was unaffected. A key finding was that milk secretion was reduced by ~75% in marginally ZD mice. By using a modified Bradford assay to measure protein content in milk, we found that ZD mice had significantly higher milk protein concentrations compared with ZA mice. In addition, we found that the amount of caseins and whey acidic protein was significantly lower in the milk of ZD mice by utilizing SDS-PAGE gel electrophoresis and staining with Coomassie Blue. Taken together, our data indicate that marginal Zn deficiency disrupts mammary gland morphology, interferes with milk secretion and alters milk composition. Due to the high prevalence of marginal Zn deficiency worldwide, well-controlled studies in women are needed to determine if marginal Zn intake during lactation has an impact on infant health and development.