Bone mineral loss during lactation occurs in absence of parathyroid tissue.
The requirement of parathyroid tissue for bone mineral loss during lactation was investigated. Lactating rats parathyroidectomized (PTX) at day 2 of lactation and consuming a 2% calcium diet are hypercalcemic and hypophosphatemic at day 13 of lactation. The high-calcium diet supports normal growth of pups nursing PTX mothers. PTX lactating rats mobilize bone mineral to the same extent as euparathyroid lactating rats consuming the same diet. Non-lactating PTX rats lose no bone mineral over a similar time period, indicating lactation-specific bone mineral mobilization in the absence of parathyroid tissue. PTX rats were verified to have physiologically insignificant amounts of parathyroid tissue, as evidenced by severe hypocalcemia and/or death in each rat after a shift from a 2% calcium to a 0.02% calcium diet. These results conclusively demonstrate that lactation-associated bone mineral mobilization does not require parathyroid hormone or parathyroid tissue.
Hodnett
D W
DW
Department of Biochemistry, University of Wisconsin-Madison, College of Agricultural and Life Sciences 53706.
DeLuca
H F
HF
Jorgensen
N A
NA
D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight; D015519:Bone Density; D002118:Calcium / Q000097:blood; D005260:Female; D005269:Femur / Q000033:anatomy & histology; D007774:Lactation / Q000502:physiology*; D009929:Organ Size; D009994:Osmolar Concentration; D010281:Parathyroid Hormone / Q000172:deficiency*; D016105:Parathyroidectomy; D010758:Phosphorus / Q000097:blood; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium