Circulating levels and function of 1,25-(OH)2D3 in lactation

Area of Science:

• Endocrinology
• Nutritional Science
• Reproductive Biology

Background:

• Vitamin D is essential for calcium homeostasis.
• Lactation presents unique physiological demands on calcium metabolism.
• The role of vitamin D during lactation requires further elucidation.

Purpose of the Study:

• To investigate the role of vitamin D in calcium homeostasis during rat lactation.
• To examine the impact of vitamin D on intestinal calcium transport and milk calcium secretion.
• To assess the effects of vitamin D deficiency on maternal and pup health during lactation.

Main Methods:

• Measurements of serum calcium, 1,25-(OH)2D3, and 25-OHD3 levels.
• Assessment of active duodenal calcium transport.
• Evaluation of pup growth, bone development, and serum biochemistry.

Main Results:

• Vitamin D is required for normal serum calcium and maximal duodenal calcium transport in lactating rats.
• Circulating 1,25-(OH)2D3 levels increase during lactation, stimulated by a slight decrease in serum calcium and parathyroid hormone.
• Vitamin D deficiency during pregnancy and lactation impairs pup growth and bone development, leading to rickets.

Conclusions:

• Vitamin D, via 1,25-(OH)2D3, plays a vital role in maternal calcium adaptation during lactation.
• Vitamin D sufficiency is critical for successful fetal development and offspring health.
• Weaning rapidly alters vitamin D and calcium metabolite levels in the mother rat.