The mRNA encoding a parathyroid hormone-like peptide is produced in mammary tissue in response to elevations in serum prolactin.
During lactation, a dramatic rise in serum PRL stimulates milk production, resulting in a substantial rise in calcium mobilization from gut and bone. We found that the production of a newly characterized calcium-mobilizing PTH-like peptide (PTH-LP) by mammary tissue was tightly linked to lactation, suggesting a possible role for PRL in the expression of PTH-LP. Here it is shown that suckling results in both an elevation in serum PRL and the appearance of PTH-LP mRNA in mammary tissue. Bromocriptine, a potent inhibitor of PRL secretion, blocked the suckling-associated rise in serum PRL and the subsequent induction of PTH-LP mRNA in mammary gland. Furthermore, injection of PRL dramatically induced PTH-LP mRNA in unsuckled puerperal glands, but not in glands on day 21 of pregnancy. Thus, the correlation between serum levels of PRL and the expression of PTH-LP mRNA in mammary tissue extends the role of PRL in milk production and suggests a possible mechanism for the PRL effects on calcium metabolism.
Thiede
M A
MA
Department of Bone Biology and Osteoporosis Research, Merck, Sharp, andDohme Research Laboratories, West Point, Pennsylvania 19486.
D000818:Animals; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics*; D044162:Parathyroid Hormone-Related Protein; D011247:Pregnancy; D011388:Prolactin / Q000097:blood*; D012333:RNA, Messenger / Q000096:biosynthesis*; D011863:Radioimmunoassay; D051381:Rats
D009363:Neoplasm Proteins; D044162:Parathyroid Hormone-Related Protein; D012333:RNA, Messenger; D011388:Prolactin; D002118:Calcium