title: Intestinal mucosal changes and upregulated calcium transporter and FGF-23 expression during lactation: Contribution of lactogenic hormone prolactin.
abstract: As the principal lactogenic hormone, prolactin (PRL) not only induces lactogenesis but also enhances intestinal calcium absorption to supply calcium for milk production. How the intestinal epithelium res-ponses to PRL is poorly understood, but it is hypothesized to increase mucosal absorptive surface area and calcium transporter expression. Herein, lactating rats were found to have greater duodenal, jejunal and ileal villous heights as well as cecal crypt depths than age-matched nulliparous rats. Morphometric analyses in the duodenum and cecum showed that their mucosal adaptations were diminished by bromocriptine, an inhibitor of pituitary PRL release. PRL also upregulated calcium transporter expression (e.g., TRPV6 and PMCA1b) in the duodenum of lactating rats. Since excessive calcium absorption could be detrimental to lactating rats, local negative regulator of calcium absorption, e.g., fibroblast growth factor (FGF)-23, should be increased. Immunohistochemistry confirmed the upregulation of FGF-23 protein expression in the duodenal and cecal mucosae of lactating rats, consistent with the enhanced FGF-23 mRNA expression in Caco-2 cells. Bromocriptine abolished this lactation-induced FGF-23 expression. Additionally, FGF-23 could negate PRL-stimulated calcium transport across Caco-2 monolayer. In conclusion, PRL was responsible for the lactation-induced mucosal adaptations, which were associated with compensatory increase in FGF-23 expression probably to prevent calcium hyperabsorption.
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Faculty of Allied Health Sciences, Burapha University, Chonburi 20131, Thailand.
authors.forename: Kannikar
authors.initials: K
authors.lastname: Wongdee
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Jarinthorn
authors.initials: J
authors.lastname: Teerapornpuntakit
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Chanakarn
authors.initials: C
authors.lastname: Sripong
authors.affiliation: Faculty of Allied Health Sciences, Burapha University, Chonburi 20131, Thailand.
authors.forename: Asma
authors.initials: A
authors.lastname: Longkunan
authors.affiliation: Faculty of Allied Health Sciences, Burapha University, Chonburi 20131, Thailand.
authors.forename: Wasutorn
authors.initials: W
authors.lastname: Chankamngoen
authors.affiliation: Faculty of Allied Health Sciences, Burapha University, Chonburi 20131, Thailand.
authors.forename: Chutiya
authors.initials: C
authors.lastname: Keadsai
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Kamonshanok
authors.initials: K
authors.lastname: Kraidith
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Nateetip
authors.initials: N
authors.lastname: Krishnamra
authors.affiliation: Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address: naratt@narattsys.com.
authors.forename: Narattaphol
authors.initials: N
authors.lastname: Charoenphandhu
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002432:Cecum / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D005260:Female; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007774:Lactation / Q000523:psychology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015220:Calcium Channels; C505605:Fgf23 protein, rat; D005346:Fibroblast Growth Factors; D011388:Prolactin; D002118:Calcium
keywords: Calcium transport; Cecum; Duodenum; Fibroblast growth factor (FGF)-23; Lactation; Prolactin