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Radojkovic DB, Pesic M, Radojkovic M, Vukelic Nikolic M, Jevtovic Stoimenov T, Radenkovic S, Ciric V, Basic D, Radjenovic Petkovic T. Significance of Duodenal Prolactin Receptor Modulation by Calcium and Vitamin D in Sulpiride-Induced Hyperprolactinemia. MEDICINA (KAUNAS, LITHUANIA) 2024; 60:942. [PMID: 38929559 PMCID: PMC11205369 DOI: 10.3390/medicina60060942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/02/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024]
Abstract
Background and Objectives: Hyperprolactinemia, as a potential side-effect of some antipsychotic medications, is associated with decreased bone density and an increased risk of fractures. This study investigates whether calcium and vitamin D supplementation affects prolactin receptor (Prlr) gene expression in the duodenum, vertebrae, and kidneys of female rats with sulpiride-induced hyperprolactinemia. Materials and Methods: Twenty-one-week-old female Wistar rats were assigned to three groups: Group S consisted of ten rats who received sulpiride injections (10 mg/kg) twice daily for 6 weeks; Group D (10 rats) received daily supplementation of 50 mg calcium and 500 IU vitamin D along with sulpiride for the last 3 weeks; and Group C consisting of seven age-matched nulliparous rats serving as a control group. Real-time PCR was used to assess Prlr gene expression in the duodenum, vertebrae, and kidneys. Results: In Group S, Prlr gene expression was notably decreased in the duodenum (p < 0.01) but elevated in the vertebrae and kidneys compared to Group C. Conversely, Group D exhibited significantly increased Prlr expression in the duodenum (p < 0.01) alongside elevated expression in the vertebrae and kidneys. Conclusions: In sulpiride-induced hyperprolactinemia, decreased Prlr gene expression in the duodenum may lead to reduced intestinal calcium absorption. Consequently, prolactin may draw calcium from the skeletal system to maintain calcium balance, facilitated by increased Prlr gene expression in the vertebrae. However, vitamin D supplementation in sulpiride-induced hyperprolactinemia notably enhances Prlr gene expression in the duodenum, potentially ameliorating intestinal calcium absorption and mitigating adverse effects on bone health.
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Affiliation(s)
- Danijela Branislav Radojkovic
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
- Clinic of Endocrinology, Diabetes and Metabolic Disorders, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia
| | - Milica Pesic
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
- Clinic of Endocrinology, Diabetes and Metabolic Disorders, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia
| | - Milan Radojkovic
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
- Surgery Clinic, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia
| | - Marija Vukelic Nikolic
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
| | - Tatjana Jevtovic Stoimenov
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
| | - Sasa Radenkovic
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
- Clinic of Endocrinology, Diabetes and Metabolic Disorders, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia
| | - Vojislav Ciric
- Medical Faculty, University of Nis, Blvd. Dr Zoran Djindjic 81, 18000 Nis, Serbia; (M.P.); (M.R.); (M.V.N.); (T.J.S.); (S.R.); (V.C.)
- Clinic of Endocrinology, Diabetes and Metabolic Disorders, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia
| | - Dijana Basic
- Psychiatry Clinic, University Clinical Center Nis, Blvd. Dr Zoran Djindjic 48, 18000 Nis, Serbia;
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Beggs MR, Young K, Plain A, O'Neill DD, Raza A, Flockerzi V, Dimke H, Alexander RT. Maternal Epidermal Growth Factor Promotes Neonatal Claudin-2 Dependent Increases in Small Intestinal Calcium Permeability. FUNCTION 2023; 4:zqad033. [PMID: 37575484 PMCID: PMC10413934 DOI: 10.1093/function/zqad033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/01/2023] [Accepted: 06/12/2023] [Indexed: 08/15/2023] Open
Abstract
A higher concentration of calcium in breast milk than blood favors paracellular calcium absorption enabling growth during postnatal development. We aimed to determine whether suckling animals have greater intestinal calcium permeability to maximize absorption and to identify the underlying molecular mechanism. We examined intestinal claudin expression at different ages in mice and in human intestinal epithelial (Caco-2) cells in response to hormones or human milk. We also measured intestinal calcium permeability in wildtype, Cldn2 and Cldn12 KO mice and Caco-2 cells in response to hormones or human milk. Bone mineralization in mice was assessed by μCT. Calcium permeability across the jejunum and ileum of mice were 2-fold greater at 2 wk than 2 mo postnatal age. At 2 wk, Cldn2 and Cldn12 expression were greater, but only Cldn2 KO mice had decreased calcium permeability compared to wildtype. This translated to decreased bone volume, cross-sectional thickness, and tissue mineral density of femurs. Weaning from breast milk led to a 50% decrease in Cldn2 expression in the jejunum and ileum. Epidermal growth factor (EGF) in breast milk specifically increased only CLDN2 expression and calcium permeability in Caco-2 cells. These data support intestinal permeability to calcium, conferred by claudin-2, being greater in suckling mice and being driven by EGF in breast milk. Loss of the CLDN2 pathway leads to suboptimal bone mineralization at 2 wk of life. Overall, EGF-mediated control of intestinal claudin-2 expression contributes to maximal intestinal calcium absorption in suckling animals.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
| | - Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Allen Plain
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Debbie D O'Neill
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ahsan Raza
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C DK-5000, Demark
- Department of Nephrology, Odense University Hospital, 5000 Odense C, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
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Abstract
Prolactin (PRL) has direct and indirect effects on bone metabolism. Experimental studies showed that in the presence of high PRL levels bone resorption was increased as well as bone formation was suppressed. Increased PRL levels in humans caused a reduction in sex hormone levels which turn may have detrimental effects on bone. Patients with hyperprolactinemia did have often decreased bone mineral density as well as an increased risk of fractures. Since PRL control may be relevant to bone health it is a clinical open issue the inclusion of skeletal health in future guidelines as indication to proactive screening, prevention and treatment particularly in high risk patients such as hyperprolactinemic women after menopause and patients with drug induced hyperprolactinemia.
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Affiliation(s)
- Luigi di Filippo
- Division of Endocrinology, IRCCS San Raffaele Hospital, San Raffaele Vita-Salute University, Via Olgettina, 58, Milan, 20132, Italy
| | - Mauro Doga
- Division of Endocrinology, IRCCS San Raffaele Hospital, San Raffaele Vita-Salute University, Via Olgettina, 58, Milan, 20132, Italy
| | - Eugenia Resmini
- Endocrinology/Medicine Departments, Hospital Sant Pau, Barcelona, Spain
| | - Andrea Giustina
- Division of Endocrinology, IRCCS San Raffaele Hospital, San Raffaele Vita-Salute University, Via Olgettina, 58, Milan, 20132, Italy.
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Mazziotti G, Frara S, Giustina A. Pituitary Diseases and Bone. Endocr Rev 2018; 39:440-488. [PMID: 29684108 DOI: 10.1210/er.2018-00005] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/16/2018] [Indexed: 12/12/2022]
Abstract
Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.
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Affiliation(s)
| | - Stefano Frara
- Institute of Endocrinology, Università Vita-Salute San Raffaele, Milan, Italy
| | - Andrea Giustina
- Institute of Endocrinology, Università Vita-Salute San Raffaele, Milan, Italy
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Beggs MR, Alexander RT. Intestinal absorption and renal reabsorption of calcium throughout postnatal development. Exp Biol Med (Maywood) 2017; 242:840-849. [PMID: 28346014 DOI: 10.1177/1535370217699536] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Calcium is vital for many physiological functions including bone mineralization. Postnatal deposition of calcium into bone is greatest in infancy and continues through childhood and adolescence until peek mineral density is reached in early adulthood. Thereafter, bone mineral density remains static until it eventually declines in later life. A positive calcium balance, i.e. more calcium absorbed than excreted, is crucial to bone deposition during growth and thus to peek bone mineral density. Dietary calcium is absorbed from the intestine into the blood. It is then filtered by the renal glomerulus and either reabsorbed by the tubule or excreted in the urine. Calcium can be (re)absorbed across intestinal and renal epithelia via both transcellular and paracellular pathways. Current evidence suggests that significant intestinal and renal calcium transport changes occur throughout development. However, the molecular details of these alterations are incompletely delineated. Here we first briefly review the current model of calcium transport in the intestine and renal tubule in the adult. Then, we describe what is known with regard to calcium handling through postnatal development, and how alterations may aid in mediating a positive calcium balance. The role of transcellular and paracellular calcium transport pathways and the contribution of specific intestinal and tubular segments vary with age. However, the current literature highlights knowledge gaps in how specifically intestinal and renal calcium (re)absorption occurs early in postnatal development. Future research should clarify the specific changes in calcium transport throughout early postnatal development including mediators of these alterations enabling appropriate bone mineralization. Impact statement This mini review outlines the current state of knowledge pertaining to the molecules and mechanisms maintaining a positive calcium balance throughout postnatal development. This process is essential to achieving optimal bone mineral density in early adulthood, thereby lowering the lifetime risk of osteoporosis.
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Affiliation(s)
- Megan R Beggs
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
| | - R Todd Alexander
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 Department of Pediatrics, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
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Tudpor K, Charoenphandhu N, Saengamnart W, Krishnamra N. Long-Term Prolactin Exposure Differentially Stimulated the Transcellular and Solvent Drag-Induced Calcium Transport in the Duodenum of Ovariectomized Rats. Exp Biol Med (Maywood) 2016; 230:836-44. [PMID: 16339748 DOI: 10.1177/153537020523001108] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Prolactin, having been shown to stimulate transcellular active and solvent drag-induced calcium transport in the duodenum of female rats, was postulated to improve duodenal calcium transport in estrogen-deficient rats. The aim of the present study was, therefore, to demonstrate the effects of long-term prolactin exposure produced by anterior pituitary (AP) transplantation on the duodenal calcium transport in young (9-week-old) and adult (22-week-old) ovariectomized rats. We found that ovariectomy did not alter the transcellular active duodenal calcium transport in young and adult rats fed normal calcium diet (1.0% w/w Ca) but decreased the solvent drag-induced duodenal calcium transport from 75.50 ± 10.12 to 55.75 ± 4.77 nmol·hr–1 cm–2 (P < 0.05) only in adult rats. Long-term prolactin exposure stimulated the transcellular active calcium transport in young and adult AP-grafted ovariectomized rats fed with normal calcium diet by more than 2-fold from 7.56 ± 0.79 to 16.54 ± 2.05 (P < 0.001) and 9.78 ± 0.72 to 15.99 ± 1.75 (P < 0.001) nmol·hr–1 cm–2, respectively. However, only the solvent drag-induced duodenal calcium transport in young rats was enhanced by prolactin from 95.51 ± 10.64 to 163.20 ± 18.03 nmol·hr–1 cm–2 (P < 0.001) whereas that in adult rats still showed a decreased flux from 75.50 ± 10.12 to 47.77 ± 5.42 nmol·hr–1 cm–2 (P < 0.05). Because oral calcium supplement has been widely used to improve calcium balance in estrogen-deficient animals, the effect of a high-calcium diet (2.0% w/w Ca) was also investigated. The results showed that stimulatory action of long-term prolactin on the transcellular active duodenal calcium transport in both young and adult rats was diminished after being fed a high-calcium diet. The same diet also abolished prolactin-enhanced solvent drag-induced duodenal calcium transport in young and further decreased that in adult AP-grafted ovariectomized rats. We concluded that the solvent drag-induced duodenal calcium transport in adult rats was decreased after ovariectomy. Long-term prolactin exposure stimulated the transcellular active duodenal calcium transport in both young and adult rats whereas enhancing the solvent drag-induced duodenal calcium transport only in young rats. Effects of prolactin were abolished by a high-calcium diet.
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Affiliation(s)
- Kukiat Tudpor
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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What Is Breast in the Bone? Int J Mol Sci 2016; 17:ijms17101764. [PMID: 27782069 PMCID: PMC5085788 DOI: 10.3390/ijms17101764] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/11/2016] [Accepted: 10/14/2016] [Indexed: 12/17/2022] Open
Abstract
The normal developmental program that prolactin generates in the mammary gland is usurped in the cancerous process and can be used out of its normal cellular context at a site of secondary metastasis. Prolactin is a pleiotropic peptide hormone and cytokine that is secreted from the pituitary gland, as well as from normal and cancerous breast cells. Experimental and epidemiologic data suggest that prolactin is associated with mammary gland development, and also the increased risk of breast tumors and metastatic disease in postmenopausal women. Breast cancer spreads to the bone in approximately 70% of cases with advanced breast cancer. Despite treatment, new bone metastases will still occur in 30%–50% of patients. Only 20% of patients with bone metastases survive five years after the diagnosis of bone metastasis. The breast cancer cells in the bone microenvironment release soluble factors that engage osteoclasts and/or osteoblasts and result in bone breakdown. The breakdown of the bone matrix, in turn, enhances the proliferation of the cancer cells, creating a vicious cycle. Recently, it was shown that prolactin accelerated the breast cancer cell-mediated osteoclast differentiation and bone breakdown by the regulation of breast cancer-secreted proteins. Interestingly, prolactin has the potential to affect multiple proteins that are involved in both breast development and likely bone metastasis, as well. Prolactin has normal bone homeostatic roles and, combined with the natural “recycling” of proteins in different tissues that can be used for breast development and function, or in bone function, increases the impact of prolactin signaling in breast cancer bone metastases. Thus, this review will focus on the role of prolactin in breast development, bone homeostasis and in breast cancer to bone metastases, covering the molecular aspects of the vicious cycle.
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Wongdee K, Charoenphandhu N. Regulation of epithelial calcium transport by prolactin: from fish to mammals. Gen Comp Endocrinol 2013; 181:235-40. [PMID: 22814336 DOI: 10.1016/j.ygcen.2012.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Accepted: 07/08/2012] [Indexed: 12/11/2022]
Abstract
Among the reported ∼300 biological actions, the established role of prolactin (PRL) is to act as a vertebrate hypercalcemic hormone that regulates epithelial calcium transport in several organs, such as the gills, intestine, and kidney. In fish, PRL stimulates the branchial calcium transport by increasing the activity of Ca(2+)-ATPase. Although this calciotropic hormone also induces hypercalcemia in amphibians, reptiles and birds, little has been known regarding the underlying mechanism. In contrast, the effects of PRL on the epithelial calcium transport in mammals are well documented. In rodents, PRL has been shown to stimulate the renal tubular calcium reabsorption and intestinal calcium absorption, the latter of which is mediated by the PRL-induced upregulation of calcium transporter gene expression and activities. Recently, we demonstrated that the duodenal calcium absorption in lactating rats was markedly enhanced by the suckling-induced PRL surge, presumably to provide calcium for milk production. The cellular and molecular mechanisms of the PRL-stimulated calcium transport in mammals have been elaborated in this review.
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Affiliation(s)
- Kannikar Wongdee
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
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Suntornsaratoon P, Wongdee K, Goswami S, Krishnamra N, Charoenphandhu N. Bone modeling in bromocriptine-treated pregnant and lactating rats: possible osteoregulatory role of prolactin in lactation. Am J Physiol Endocrinol Metab 2010; 299:E426-36. [PMID: 20551289 DOI: 10.1152/ajpendo.00134.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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.
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Charoenphandhu N, Wongdee K, Krishnamra N. Is prolactin the cardinal calciotropic maternal hormone? Trends Endocrinol Metab 2010; 21:395-401. [PMID: 20304671 DOI: 10.1016/j.tem.2010.02.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Revised: 02/03/2010] [Accepted: 02/04/2010] [Indexed: 12/14/2022]
Abstract
To produce offspring, mothers require a large amount of calcium for fetal growth and milk production. Increased calcium demand leads to enhanced intestinal calcium absorption and stockpiling of bone calcium in pregnancy prior to demineralization in lactation. These coordinated events must be carefully organized by calciotropic hormone(s), but the classical hormones, namely 1,25-dihydroxyvitamin D(3), parathyroid hormone and calcitonin, do not appear to be responsible. Plasma prolactin (PRL) levels are elevated during pregnancy and, in view of the presence of PRL receptors in gut, bone and mammary glands, as well as recent evidence of the stimulatory effects of PRL on intestinal calcium transport, bone resorption and mammary calcium secretion, we postulate that PRL is the cardinal calciotropic hormone during pregnancy and lactation.
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Charoenphandhu N, Nakkrasae LI, Kraidith K, Teerapornpuntakit J, Thongchote K, Thongon N, Krishnamra N. Two-step stimulation of intestinal Ca(2+) absorption during lactation by long-term prolactin exposure and suckling-induced prolactin surge. Am J Physiol Endocrinol Metab 2009; 297:E609-19. [PMID: 19567804 DOI: 10.1152/ajpendo.00347.2009] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During pregnancy and lactation, the enhanced intestinal Ca(2+) absorption serves to provide Ca(2+) for fetal development and lactogenesis; however, the responsible hormone and its mechanisms remain elusive. We elucidated herein that prolactin (PRL) markedly stimulated the transcellular and paracellular Ca(2+) transport in the duodenum of pregnant and lactating rats as well as in Caco-2 monolayer in a two-step manner. Specifically, a long-term exposure to PRL in pregnancy and lactation induced an adaptation in duodenal cells at genomic levels by upregulating the expression of genes related to transcellular transport, e.g., TRPV5/6 and calbindin-D(9k), and the paracellular transport, e.g., claudin-3, thereby raising Ca(2+) absorption rate to a new "baseline" (Step 1). During suckling, PRL surge further increased Ca(2+) absorption to a higher level (Step 2) in a nongenomic manner to match Ca(2+) loss in milk. PRL-enhanced apical Ca(2+) uptake was responsible for the increased transcellular transport, whereas PRL-enhanced paracellular transport required claudin-15, which regulated epithelial cation selectivity and paracellular Ca(2+) movement. Such nongenomic PRL actions were mediated by phosphoinositide 3-kinase, protein kinase C, and RhoA-associated coiled-coil-forming kinase pathways. In conclusion, two-step stimulation of intestinal Ca(2+) absorption resulted from long-term PRL exposure, which upregulated Ca(2+) transporter genes to elevate the transport baseline, and the suckling-induced transient PRL surge, which further increased Ca(2+) transport to the maximal capacity. The present findings also suggested that Ca(2+) supplementation at 15-30 min prior to breastfeeding may best benefit the lactating mother, since more Ca(2+) could be absorbed as a result of the suckling-induced PRL surge.
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Charoenphandhu N, Wongdee K, Teerapornpuntakit J, Thongchote K, Krishnamra N. Transcriptome responses of duodenal epithelial cells to prolactin in pituitary-grafted rats. Mol Cell Endocrinol 2008; 296:41-52. [PMID: 18951951 DOI: 10.1016/j.mce.2008.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 09/19/2008] [Accepted: 09/22/2008] [Indexed: 11/27/2022]
Abstract
Chronic prolactin (PRL) exposure can affect several functions of duodenal epithelia, especially those associated with fluid and electrolyte transport. However, little is known regarding its molecular mechanism. To identify PRL-regulated genes, microarray analysis was performed on RNA samples from duodenal epithelial cells of anterior pituitary (AP)-grafted hyperprolactinemic rats. Herein, we identified 321 transcripts upregulated and 241 transcripts downregulated after 4 weeks of AP transplantation. Results from real-time PCR analyses of 15 selected genes were consistent with the microarray results. Gene ontology analysis demonstrated pleiotropic effects of PRL on several cellular processes, including cellular metabolic process, cell communication and cell adhesion. Interestingly, 17 upregulated transcripts and 12 downregulated transcripts are involved in the transport of ions and nutrients, e.g., Ca(2+), Na(+), K(+), Cl(-) and glucose, thus agreeing with the established action of PRL on electrolyte homeostasis. The present results provided fundamental information for further investigations on mechanism of PRL actions in the intestine.
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Seriwatanachai D, Thongchote K, Charoenphandhu N, Pandaranandaka J, Tudpor K, Teerapornpuntakit J, Suthiphongchai T, Krishnamra N. Prolactin directly enhances bone turnover by raising osteoblast-expressed receptor activator of nuclear factor kappaB ligand/osteoprotegerin ratio. Bone 2008; 42:535-46. [PMID: 18166509 DOI: 10.1016/j.bone.2007.11.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 11/02/2007] [Accepted: 11/15/2007] [Indexed: 11/29/2022]
Abstract
Hyperprolactinemia leads to high bone turnover as a result of enhanced bone formation and resorption. Although its osteopenic effect has long been explained as hyperprolactinemia-induced hypogonadism, identified prolactin (PRL) receptors in osteoblasts suggested a possible direct action of PRL on bone. In the present study, we found that hyperprolactinemia induced by anterior pituitary transplantation (AP), with or without ovariectomy (Ovx), had no detectable effect on bone mineral density and content measured by dual-energy X-ray absorptiometry (DXA). However, histomorphometric studies revealed increases in the osteoblast and osteoclast surfaces in the AP rats, but a decrease in the osteoblast surface in the AP+Ovx rats. The resorptive activity was predominant since bone volume and trabecular number were decreased, and the trabecular separation was increased in both groups. Estrogen supplement (E2) fully reversed the effect of estrogen depletion in the Ovx but not in the AP+Ovx rats. In contrast to the typical Ovx rats, bone formation and resorption became uncoupled in the AP+Ovx rats. Therefore, hyperprolactinemia was likely to have some estrogen-independent and/or direct actions on bone turnover. Osteoblast-expressed PRL receptor transcripts and proteins shown in the present study confirmed our hypothesis. Furthermore, we demonstrated that the osteoblast-like cells, MG-63, directly exposed to PRL exhibited lower expression of alkaline phosphatase and osteocalcin mRNA, and a decrease in alkaline phosphatase activity. The ratios of receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) proteins were increased, indicating an increase in the osteoclastic bone resorption. The present data thus demonstrated that hyperprolactinemia could act directly on bone to stimulate bone turnover, with more influence on bone resorption than formation. PRL enhanced bone resorption in part by increasing RANKL and decreasing OPG expressions by osteoblasts.
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Jantarajit W, Thongon N, Pandaranandaka J, Teerapornpuntakit J, Krishnamra N, Charoenphandhu N. Prolactin-stimulated transepithelial calcium transport in duodenum and Caco-2 monolayer are mediated by the phosphoinositide 3-kinase pathway. Am J Physiol Endocrinol Metab 2007; 293:E372-84. [PMID: 17488805 DOI: 10.1152/ajpendo.00142.2007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Prolactin (PRL) has been shown to stimulate intestinal calcium absorption but the mechanism was still unknown. This study aimed to investigate the mechanism and signaling pathway by which PRL enhanced calcium transport in the rat duodenum and Caco-2 monolayer. Both epithelia strongly expressed mRNAs and proteins of PRL receptors. Ussing chamber technique showed that the duodenal active calcium fluxes were increased by PRL in a dose-response manner with the maximal effective dose of 800 ng/ml. This response diminished after exposure to LY-294002, a phosphoinositide 3-kinase (PI3K) inhibitor. Caco-2 monolayer gave similar response to PRL with the maximal effective dose of 600 ng/ml. By nullifying the transepithelial potential difference, we showed that the voltage-dependent paracellular calcium transport did not contribute to the PRL-enhanced flux in Caco-2 monolayer. In contrast, the calcium gradient-dependent paracellular transport and calcium permeability were increased by PRL. Effects of PRL on Caco-2 monolayer were abolished by PI3K inhibitors (LY-294002 and wortmannin), but not by inhibitors of MEK (U-0126) or JAK2 (AG-490). To investigate whether the PRL-enhanced paracellular transport was linked to changes in the epithelial charge selectivity, the permeability ratio of sodium and chloride (P(Na)/P(Cl)) was determined. We found that PRL elevated the P(Na)/P(Cl) in both epithelia, and the effects were blocked by PI3K inhibitors. In conclusion, PRL directly and rapidly stimulated the active and passive calcium transport in the rat duodenum and Caco-2 monolayer via the nongenomic PI3K-signaling pathway. This PRL-enhanced paracellular calcium transport could have resulted from altered charge selectivity.
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Affiliation(s)
- Walailuk Jantarajit
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
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Charoenphandhu N, Tudpor K, Thongchote K, Saengamnart W, Puntheeranurak S, Krishnamra N. High-calcium diet modulates effects of long-term prolactin exposure on the cortical bone calcium content in ovariectomized rats. Am J Physiol Endocrinol Metab 2007; 292:E443-52. [PMID: 17003239 DOI: 10.1152/ajpendo.00333.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High physiological prolactin induced positive calcium balance by stimulating intestinal calcium absorption, reducing renal calcium excretion, and increasing bone calcium deposition in female rats. Although prolactin-induced increase in trabecular bone calcium deposition was absent after ovariectomy, its effects on cortical bones were still controversial. The present investigation, therefore, aimed to study the effect of in vivo long-term high physiological prolactin induced by either anterior pituitary (AP) transplantation or 2.5 mg/kg prolactin injection on cortical bones in ovariectomized rats. Since the presence of prolactin receptors (PRLR) in different bones of normal adult rats has not been reported, we first determined mRNA expression of both short- and long-form PRLRs at the cortical sites (tibia and femur) and trabecular sites (calvaria and vertebrae) by using the RT-PCR. Our results showed the mRNA expression of both PRLR isoforms with predominant long form at all sites. However, high prolactin levels induced by AP transplantation in normal rats did not have any effect on the femoral bone mineral density or bone mineral content. By using (45)Ca kinetic study, 2.5 mg/kg prolactin did not alter bone formation, bone resorption, calcium deposition, and total calcium content in tibia and femur of adult ovariectomized rats. AP transplantation also had no effect on the cortical total calcium content in adult ovariectomized rats. Because previous work showed that the effects of prolactin were age dependent and could be modulated by high-calcium diet, interactions between prolactin and these two parameters were investigated. The results demonstrated that 2.0% wt/wt high-calcium diet significantly increased the tibial total calcium content in 9-wk-old young AP-grafted ovariectomized rats but decreased the tibial total calcium content in 22-wk-old adult rats. As for the vertebrae, the total calcium contents in both young and adult rats were not changed by high-calcium diet. The present results thus indicated that the adult cortical bones were potentially direct targets of prolactin. Moreover, the effects of high physiological prolactin on cortical bones were age dependent and were observed only under the modulation of high-calcium diet condition.
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Amnattanakul S, Charoenphandhu N, Limlomwongse L, Krishnamra N. Endogenous prolactin modulated the calcium absorption in the jejunum of suckling rats. Can J Physiol Pharmacol 2005; 83:595-604. [PMID: 16091785 DOI: 10.1139/y05-045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prolactin has been reported to stimulate intestinal calcium absorption in young and mature, but not aging rats. The present study was performed on suckling rats to elucidate the actions of endogenous prolactin on calcium absorption in various intestinal segments. Before measuring the calcium fluxes, 9-day-old rats were administered for 7 days with 0.9% NaCl, s.c. (control), 3 mg/kg bromocriptine, i.p., twice daily to abolish secretion of endogenous pro lac tin, or bromocriptine plus exogenous 2.5 mg/kg prolactin, s.c. Thereafter, the 16-day-old rats were experimented upon by instilling the45Ca-containing solution into the intestinal segments. The results showed that, under a physiological condition, the jejunum had the highest rate of calcium absorption compared with other segments (1.4 ± 0.35 µmol·h1·cm1, p < 0.05). The duodenum and ileum also manifested calcium absorption, whereas the colon showed calcium secretion. Lack of endogenous prolactin decreased lumen-to-plasma and net calcium fluxes in jejunum from 2.07 ± 0.31 to 1.19 ± 0.12 and 1.40 ± 0.35 to 0.88 ± 0.18 µmol·h1·cm1(p < 0.05), respectively, and exogenous prolactin restored the jejunal calcium absorption to the control value. Endogenous prolactin also had an effect on the duodenum but, in this case, exogenous prolactin did not reverse the effect of bromocriptine. However, neither ileal nor colonic calcium fluxes were influenced by prolactin. Because luminal sodium concentration has been demonstrated to affect calcium absorption in mature rats, the effect of varying luminal sodium concentrations on calcium fluxes in suckling rats was evaluated. The jejunum was used due to its highest rate of calcium absorption. After filling the jejunal segments with 124 (control), 80, 40 mmol/L Na+-containing or Na+-free solution, increases in calcium absorption were found to be inversely related to luminal sodium concentrations in both control and bromocriptine-treated rats. The plasma concentration of45Ca under luminal sodium free condition was also higher than that of the control condition (2.26% ± 0.07% vs. 2.01% ± 0.09% administered dose, p < 0.05). However,3H-mannitol, a marker of the widening of tight junction that was introduced into the lumen, had a stable level in the plasma during an increase in plasma45Ca, suggesting that the widening of tight junction was not required for enhanced calcium absorption. In conclusion, calcium absorption in suckling rats was of the highest rate in the jejunum where endogenous prolactin modulated calcium absorption without increasing the paracellular transport of mannitol. Key words: calcium absorption, intestinal segments, prolactin, suckling rats.
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Affiliation(s)
- Suwimol Amnattanakul
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
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Tanrattana C, Charoenphandhu N, Limlomwongse L, Krishnamra N. Prolactin directly stimulated the solvent drag-induced calcium transport in the duodenum of female rats. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1665:81-91. [PMID: 15471574 DOI: 10.1016/j.bbamem.2004.06.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Revised: 06/22/2004] [Accepted: 06/29/2004] [Indexed: 11/23/2022]
Abstract
Prolactin has been reported to stimulate the calcium absorption of the duodenum where three components of the active calcium transport, namely transcellular active, voltage-dependent and solvent drag-induced calcium transport, were identified. It was known that the transcellular active, but not the voltage-dependent, duodenal calcium transport was directly stimulated by prolactin. The present study thus aimed to evaluate the direct action of prolactin on the solvent drag-induced duodenal calcium transport by using the Ussing chamber technique. The jejunum was used as a reference for the existence of solvent drag and the widening of tight junction induced by cytochalasin E. Results showed that the solvent drag-induced calcium transport existed in both intestinal segments, but the magnitude was significantly greater in the duodenum (29.27+/-2.27 vs. 17.31+/-1.65 nmol h(-1) cm(-2), P<0.001). We further demonstrated that 200, 600 and 800, but not 1000 ng/ml, prolactin significantly promoted the solvent drag-induced duodenal calcium transport in a dose-response manner, i.e. from the control value of (nmol h(-1) cm(-2)) 24.31+/-2.36 to 45.42+/-3.47 (P<0.01), 63.82+/-5.28 (P<0.001) and 53.93+/-5.41 (P<0.01), respectively. However, prolactin did not manifest any effect on the jejunum. Because the paracellular transport was suggested to be size-selective as well as charge-selective, further experiments were designed to evaluate the mechanism by which prolactin stimulated the solvent drag-induced calcium transport. The duodenum was exposed to 20 microM cytochalasin E, 600 ng/ml prolactin or the combination of both in the presence of a paracellular marker 3H-mannitol, while the jejunum was a positive reference. The results showed that, in the jejunum, cytochalasin E alone and cytochalasin E plus prolactin significantly increased the mannitol fluxes from (micromol h(-1) cm(-2)) 0.29+/-0.04 to 0.49+/-0.03 (P<0.05) and 0.48+/-0.05 (P<0.05), respectively, while having no effect on the calcium fluxes. Prolactin alone had no effect on the jejunal calcium flux. In the duodenum, neither mannitol nor calcium fluxes were enhanced by cytochalasin E, however, prolactin still increased the solvent drag-induced calcium flux from 27.74+/-2.41 to 51.03+/-4.35 nmol h(-1) cm(-2) (P<0.001). It was concluded that prolactin directly stimulated the solvent drag-induced duodenal calcium transport in a dose-response and biphasic manner without the widening of tight junction.
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Affiliation(s)
- Chaiyot Tanrattana
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
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