Publication: Bone modeling in bromocriptine-treated pregnant and lactating rats: Possible osteoregulatory role of prolactin in lactation
Issued Date
2010-09-01
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ISSN
15221555
01931849
01931849
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2-s2.0-77956816831
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Mahidol University
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SCOPUS
Bibliographic Citation
American Journal of Physiology - Endocrinology and Metabolism. Vol.299, No.3 (2010)
Suggested Citation
Panan Suntornsaratoon, Kannikar Wongdee, Suchandra Goswami, Nateetip Krishnamra, Narattaphol Charoenphandhu Bone modeling in bromocriptine-treated pregnant and lactating rats: Possible osteoregulatory role of prolactin in lactation. American Journal of Physiology - Endocrinology and Metabolism. Vol.299, No.3 (2010). doi:10.1152/ajpendo.00134.2010 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/28643
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Title
Bone modeling in bromocriptine-treated pregnant and lactating rats: Possible osteoregulatory role of prolactin in lactation
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Abstract
The lactogenic hormone prolactin (PRL) directly regulates osteoblast functions in vitro and modulates bone remodeling in nulliparous rats, but its osteoregulatory roles in pregnant and lactating rats with physiological hyperprolactinemia remained unclear. Herein, bone changes were investigated in rats treated with bromocriptine (Bromo), an inhibitor of pituitary PRL release, or Bromo+PRL at different reproductive phases, from mid-pregnancy to late lactation. PRL receptors were strongly expressed in osteoblasts lining bone trabeculae, indicating bone as a target of PRL actions. By using dual energy X-ray absorptiometry, we found a significant increase in bone mineral density in the femora and vertebrae of pregnant rats. Such pregnancy-induced bone gain was, however, PRL independent and may have resulted from the increased cortical thickness. Bone trabeculae were modestly changed during pregnancy as evaluated by bone histomorphometry. On the other hand, lactating rats, especially in late lactation, showed massive bone loss in bone trabeculae but not in cortical shells. Further study in Bromo- and Bromo+PRL-treated rats suggested that PRL contributed to decreases in trabecular bone volume and number and increases in trabecular separation and eroded surface, as well as a paradoxical increase in bone formation rate in late lactation. Uncoupling of trabecular bone formation and resorption was evident in lactating rats, with the latter being predominant. In conclusion, pregnancy mainly induced cortical bone gain, whereas lactation led to trabecular bone loss in both long bones and vertebrae. Although PRL was not responsible for the pregnancy-induced bone gain, it was an important regulator of bone modeling during lactation. Copyright © 2010 the American Physiological Society.