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Jiang H, Chanpaisaeng K, Christakos S, Fleet JC. Intestinal Vitamin D Receptor Is Dispensable for Maintaining Adult Bone Mass in Mice With Adequate Calcium Intake. Endocrinology 2023; 164:bqad051. [PMID: 36960562 PMCID: PMC10282920 DOI: 10.1210/endocr/bqad051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/03/2023] [Accepted: 03/22/2023] [Indexed: 03/25/2023]
Abstract
1,25-Dihydroxyvitamin D3 (1,25(OH)2D3)-mediated intestinal calcium (Ca) absorption supplies Ca for proper bone mineralization during growth. We tested whether vitamin D receptor (VDR)-mediated 1,25(OH)2D3 signaling is critical for adult Ca absorption and bone by using mice with inducible Vdr gene knockout in the whole intestine (villin-CreERT2+/- × Vdrf/f, WIK) or in the large intestine (Cdx2-CreERT2+/- ×Vdrf/f, LIK). At 4-month-old, Vdr alleles were recombined (0.05 mg tamoxifen/g BW, intraperitoneally [i.p.], 5 days) and mice were fed diets with either 0.5% (adequate) or 0.2% (low) Ca. Ca absorption was examined after 2 weeks while serum 1,25(OH)2D3, bone mass, and bone microarchitecture were examined after 16 weeks. Intestinal and renal gene expression was measured at both time points (n = 12/genotype/diet/time point). On the 0.5% Ca diet, all phenotypes in WIK and LIK mice were similar to the controls. Control mice adapted to the 0.2% low-Ca diet by increasing renal Cyp27b1 mRNA (3-fold), serum 1,25(OH)2D3 level (1.9-fold), and Ca absorption in the duodenum (Dd, + 131%) and proximal colon (PCo, + 28.9%), which prevented bone loss. In WIK mice, low-Ca diet increased serum 1,25(OH)2D3 (4.4-fold) but Ca absorption remained unaltered in the Dd and PCo. Consequently, significant bone loss occurred in WIK mice (e.g., cortical thickness, Ct.Th, -33.7%). LIK mice adapted to the low-Ca diet in the Dd but not the PCo, and the effect on bone phenotypes was milder (e.g., Ct.Th, -13.1%). Our data suggest intestinal VDR in adult mice prevents bone loss under low Ca intake but is dispensable under adequate calcium intake.
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Affiliation(s)
- Heng Jiang
- Department of Nutritional Sciences, Dell Pediatric Research Institute, University of Texas, Austin, TX 78723, USA
| | - Krittikan Chanpaisaeng
- Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand
| | - Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - James C Fleet
- Department of Nutritional Sciences, Dell Pediatric Research Institute, University of Texas, Austin, TX 78723, USA
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2
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Wongdee K, Chanpaisaeng K, Teerapornpuntakit J, Charoenphandhu N. Intestinal Calcium Absorption. Compr Physiol 2021; 11:2047-2073. [PMID: 34058017 DOI: 10.1002/cphy.c200014] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this article, we focus on mammalian calcium absorption across the intestinal epithelium in normal physiology. Intestinal calcium transport is essential for supplying calcium for metabolism and bone mineralization. Dietary calcium is transported across the mucosal epithelia via saturable transcellular and nonsaturable paracellular pathways, both of which are under the regulation of 1,25-dihydroxyvitamin D3 and several other endocrine and paracrine factors, such as parathyroid hormone, prolactin, 17β-estradiol, calcitonin, and fibroblast growth factor-23. Calcium absorption occurs in several segments of the small and large intestine with varying rates and capacities. Segmental heterogeneity also includes differential expression of calcium transporters/carriers (e.g., transient receptor potential cation channel and calbindin-D9k ) and the presence of favorable factors (e.g., pH, luminal contents, and gut motility). Other proteins and transporters (e.g., plasma membrane vitamin D receptor and voltage-dependent calcium channels), as well as vesicular calcium transport that probably contributes to intestinal calcium absorption, are also discussed. © 2021 American Physiological Society. Compr Physiol 11:1-27, 2021.
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Affiliation(s)
- Kannikar Wongdee
- Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Krittikan Chanpaisaeng
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Jarinthorn Teerapornpuntakit
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Narattaphol Charoenphandhu
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand.,The Academy of Science, The Royal Society of Thailand, Bangkok, Thailand
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3
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Tiyasatkulkovit W, Aksornthong S, Adulyaritthikul P, Upanan P, Wongdee K, Aeimlapa R, Teerapornpuntakit J, Rojviriya C, Panupinthu N, Charoenphandhu N. Excessive salt consumption causes systemic calcium mishandling and worsens microarchitecture and strength of long bones in rats. Sci Rep 2021; 11:1850. [PMID: 33473159 PMCID: PMC7817681 DOI: 10.1038/s41598-021-81413-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 01/06/2021] [Indexed: 02/06/2023] Open
Abstract
Excessive salt intake has been associated with the development of non-communicable diseases, including hypertension with several cardiovascular consequences. Although the detrimental effects of high salt on the skeleton have been reported, longitudinal assessment of calcium balance together with changes in bone microarchitecture and strength under salt loading has not been fully demonstrated. To address these unanswered issues, male Sprague-Dawley rats were fed normal salt diet (NSD; 0.8% NaCl) or high salt diet (HSD; 8% NaCl) for 5 months. Elevation of blood pressure, cardiac hypertrophy and glomerular deterioration were observed in HSD, thus validating the model. The balance studies were performed to monitor calcium input and output upon HSD challenge. The HSD-induced increase in calcium losses in urine and feces together with reduced fractional calcium absorption led to a decrease in calcium retention. With these calcium imbalances, we therefore examined microstructural changes of long bones of the hind limbs. Using the synchrotron radiation x-ray tomographic microscopy, we showed that trabecular structure of tibia and femur of HSD displayed a marked increase in porosity. Consistently, the volumetric micro-computed tomography also demonstrated a significant decrease in trabecular bone mineral density with expansion of endosteal perimeter in the tibia. Interestingly, bone histomorphometric analyses indicated that salt loading caused an increase in osteoclast number together with decreases in osteoblast number and osteoid volume. This uncoupling process of bone remodeling in HSD might underlie an accelerated bone loss and bone structural changes. In conclusion, long-term excessive salt consumption leads to impairment of skeletal mass and integrity possibly through negative calcium balance.
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Affiliation(s)
- Wacharaporn Tiyasatkulkovit
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.7922.e0000 0001 0244 7875Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
| | - Sirion Aksornthong
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400 Thailand
| | - Punyanuch Adulyaritthikul
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400 Thailand
| | - Pornpailin Upanan
- grid.411825.b0000 0000 9482 780XFaculty of Allied Health Sciences, Burapha University, Chonburi, 20131 Thailand
| | - Kannikar Wongdee
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.411825.b0000 0000 9482 780XFaculty of Allied Health Sciences, Burapha University, Chonburi, 20131 Thailand
| | - Ratchaneevan Aeimlapa
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400 Thailand
| | - Jarinthorn Teerapornpuntakit
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.412029.c0000 0000 9211 2704Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000 Thailand
| | - Catleya Rojviriya
- grid.472685.aSynchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, 30000 Thailand
| | - Nattapon Panupinthu
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400 Thailand
| | - Narattaphol Charoenphandhu
- grid.10223.320000 0004 1937 0490Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400 Thailand ,grid.10223.320000 0004 1937 0490Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170 Thailand ,The Academy of Science, The Royal Society of Thailand, Dusit, Bangkok, 10300 Thailand
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Tiyasatkulkovit W, Promruk W, Rojviriya C, Pakawanit P, Chaimongkolnukul K, Kengkoom K, Teerapornpuntakit J, Panupinthu N, Charoenphandhu N. Impairment of bone microstructure and upregulation of osteoclastogenic markers in spontaneously hypertensive rats. Sci Rep 2019; 9:12293. [PMID: 31444374 PMCID: PMC6707260 DOI: 10.1038/s41598-019-48797-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022] Open
Abstract
Hypertension and osteoporosis are the major non-communicable diseases in the elderly worldwide. Although clinical studies reported that hypertensive patients experienced significant bone loss and likelihood of fracture, the causal relationship between hypertension and osteoporosis has been elusive due to other confounding factors associated with these diseases. In this study, spontaneously hypertensive rats (SHR) were used to address this relationship and further explored the biophysical properties and the underlying mechanisms. Long bones of the hind limbs from 18-week-old female SHR were subjected to determination of bone mineral density (BMD) and their mechanical properties. Using synchrotron radiation X-ray tomographic microscopy (SRXTM), femoral heads of SHR displayed marked increase in porosity within trabecular area together with decrease in cortical thickness. The volumetric micro-computed tomography also demonstrated significant decreases in trabecular BMD, cortical thickness and total cross-sectional area of the long bones. These changes also led to susceptibility of the long bones to fracture indicated by marked decreases in yield load, stiffness and maximum load using three-point bending tests. At the cellular mechanism, an increase in the expression of osteoclastogenic markers with decrease in the expression of alkaline phosphatase was found in primary osteoblast-enriched cultures isolated from long bones of these SHR suggesting an imbalance in bone remodeling. Taken together, defective bone mass and strength in hypertensive rats were likely due to excessive bone resorption. Development of novel therapeutic interventions that concomitantly target hypertension and osteoporosis should be helpful in reduction of unwanted outcomes, such as bone fractures, in elderly patients.
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Affiliation(s)
- Wacharaporn Tiyasatkulkovit
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Worachet Promruk
- 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
| | - Catleya Rojviriya
- Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, 30000, Thailand
| | - Phakkhananan Pakawanit
- Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, 30000, Thailand
| | | | - Kanchana Kengkoom
- National Laboratory Animal Center, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - Jarinthorn Teerapornpuntakit
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand
| | - Nattapon Panupinthu
- 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
| | - Narattaphol Charoenphandhu
- 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. .,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170, Thailand. .,The Academy of Science, The Royal Society of Thailand, Dusit, Bangkok, 10300, Thailand.
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Eaimworawuthikul S, Tunapong W, Chunchai T, Suntornsaratoon P, Charoenphandhu N, Thiennimitr P, Chattipakorn N, Chattipakorn SC. Altered gut microbiota ameliorates bone pathology in the mandible of obese-insulin-resistant rats. Eur J Nutr 2019; 59:1453-1462. [PMID: 31123863 DOI: 10.1007/s00394-019-02002-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/16/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE The chronic consumption of a high-fat diet (HFD) induces obese-insulin resistance and impairs jawbone health via gut dysbiosis-stimulated inflammatory process. Our previous studies demonstrated that the probiotic Lactobacillus paracasei HII01, prebiotic xylooligosaccharide (XOS), and synbiotics improved several vital organ functions by reducing gut dysbiosis in HFD-induced obese rats. However, the impacts on the cellular level of jawbone microarchitecture have not been examined. Here, we hypothesized that the supplementation of L. paracasei HII01, XOS, and synbiotics ameliorated the bone microarchitectural pathology in HFD-fed rats by reducing systemic inflammation and other metabolic parameters. METHODS The dietary regimes (normal or high-fat diet) were provided to 48 male Wistar rats throughout 24-week experiment. After week 12, rats were given either a vehicle, pro-, pre-, or synbiotic for an additional 12 weeks before being killed. Then, blood analyses and bone histomorphometry of the jawbones were performed. RESULTS The HFD-fed rats developed obese-insulin resistance with significantly elevated systemic inflammation. Bone histomorphometry of these rats showed a decrease in trabecular thickness with increased osteoclasts and active erosion surfaces. Mineral apposition and bone-formation rates were also remarkably diminished. The treatment with pro-, pre-, and synbiotics equally improved metabolic disturbance, reduced systemic inflammation, increased trabecular thickness, decreased osteoclasts and active erosion surfaces and restored mineral apposition and bone-formation rates. CONCLUSION The probiotic L. paracasei HII01, prebiotic XOS, and the synbiotics had similarly beneficial effects to improve jawbone microarchitecture in HFD-fed rats by possibly ameliorating osteoclast-related bone resorption and potentiating bone-formation activities.
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Affiliation(s)
- Sathima Eaimworawuthikul
- Department of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, 50200, Thailand.,Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, 50200, Thailand.,Neurophysiology Unit, Center of Excellence in Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Wannipa Tunapong
- Neurophysiology Unit, Center of Excellence in Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Titikorn Chunchai
- Neurophysiology Unit, Center of Excellence in Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Panan Suntornsaratoon
- 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
| | - Narattaphol Charoenphandhu
- 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.,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170, Thailand.,The Academy of Science, The Royal Society of Thailand, Dusit, Bangkok, 10300, Thailand
| | - Parameth Thiennimitr
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Center of Excellence in Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Siriporn C Chattipakorn
- Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, 50200, Thailand. .,Neurophysiology Unit, Center of Excellence in Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
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6
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Wongdee K, Krishnamra N, Charoenphandhu N. Derangement of calcium metabolism in diabetes mellitus: negative outcome from the synergy between impaired bone turnover and intestinal calcium absorption. J Physiol Sci 2017; 67:71-81. [PMID: 27671701 PMCID: PMC10717635 DOI: 10.1007/s12576-016-0487-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 09/06/2016] [Indexed: 12/31/2022]
Abstract
Both types 1 and 2 diabetes mellitus (T1DM and T2DM) are associated with profound deterioration of calcium and bone metabolism, partly from impaired intestinal calcium absorption, leading to a reduction in calcium uptake into the body. T1DM is associated with low bone mineral density (BMD) and osteoporosis, whereas the skeletal changes in T2DM are variable, ranging from normal to increased and to decreased BMD. However, both types of DM eventually compromise bone quality through production of advanced glycation end products and misalignment of collagen fibrils (so-called matrix failure), thereby culminating in a reduction of bone strength. The underlying cellular mechanisms (cellular failure) are related to suppression of osteoblast-induced bone formation and bone calcium accretion, as well as to enhancement of osteoclast-induced bone resorption. Several other T2DM-related pathophysiological changes, e.g., osteoblast insulin resistance, impaired productions of osteogenic growth factors (particularly insulin-like growth factor 1 and bone morphogenetic proteins), overproduction of pro-inflammatory cytokines, hyperglycemia, and dyslipidemia, also aggravate diabetic osteopathy. In the kidney, DM and the resultant hyperglycemia lead to calciuresis and hypercalciuria in both humans and rodents. Furthermore, DM causes deranged functions of endocrine factors related to mineral metabolism, e.g., parathyroid hormone, 1,25-dihydroxyvitamin D3, and fibroblast growth factor-23. Despite the wealth of information regarding impaired bone remodeling in DM, the long-lasting effects of DM on calcium metabolism in young growing individuals, pregnant women, and neonates born to women with gestational DM have received scant attention, and their underlying mechanisms are almost unknown and worth exploring.
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Affiliation(s)
- Kannikar Wongdee
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand
| | - Nateetip Krishnamra
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand
| | - Narattaphol Charoenphandhu
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
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Abstract
For humans and rodents, duodenum is a very important site of calcium absorption since it is exposed to ionized calcium released from dietary complexes by gastric acid. Calcium traverses the duodenal epithelium via both transcellular and paracellular pathways in a vitamin D-dependent manner. After binding to the nuclear vitamin D receptor, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] upregulates the expression of several calcium transporter genes, e.g., TRPV5/6, calbindin-D9k, plasma membrane Ca(2+)-ATPase1b, and NCX1, thereby enhancing the transcellular calcium transport. This action has been reported to be under the regulation of parathyroid-kidney-intestinal and bone-kidney-intestinal axes, in which the plasma calcium and fibroblast growth factor-23 act as negative feedback regulators, respectively. 1,25(OH)2D3 also modulates the expression of tight junction-related genes and convective water flow, presumably to increase the paracellular calcium permeability and solvent drag-induced calcium transport. However, vitamin D-independent calcium absorption does exist and plays an important role in calcium homeostasis under certain conditions, particularly in neonatal period, pregnancy, and lactation as well as in naturally vitamin D-impoverished subterranean mammals.
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8
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Alexander RT, Rievaj J, Dimke H. Paracellular calcium transport across renal and intestinal epithelia. Biochem Cell Biol 2014; 92:467-80. [PMID: 25386841 DOI: 10.1139/bcb-2014-0061] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium (Ca(2+)) is a key constituent in a myriad of physiological processes from intracellular signalling to the mineralization of bone. As a consequence, Ca(2+) is maintained within narrow limits when circulating in plasma. This is accomplished via regulated interplay between intestinal absorption, renal tubular reabsorption, and exchange with bone. Many studies have focused on the highly regulated active transcellular transport pathways for Ca(2+) from the duodenum of the intestine and the distal nephron of the kidney. However, comparatively little work has examined the molecular constituents creating the paracellular shunt across intestinal and renal epithelium, the transport pathway responsible for the majority of transepithelial Ca(2+) flux. More specifically, passive paracellular Ca(2+) absorption occurs across the majority of the intestine in addition to the renal proximal tubule and thick ascending limb of Henle's loop. Importantly, recent studies demonstrated that Ca(2+) transport through the paracellular shunt is significantly regulated. Therefore, we have summarized the evidence for different modes of paracellular Ca(2+) flux across renal and intestinal epithelia and highlighted recent molecular insights into both the mechanism of secondarily active paracellular Ca(2+) movement and the identity of claudins that permit the passage of Ca(2+) through the tight junction of these epithelia.
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Affiliation(s)
- R Todd Alexander
- a Department of Pediatrics, The University of Alberta, 4-585 Edmonton Clinic Health Academy, 11405 - 87 Ave, Edmonton, AB T6G 2R7, Canada
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Suntornsaratoon P, Kraidith K, Teerapornpuntakit J, Dorkkam N, Wongdee K, Krishnamra N, Charoenphandhu N. Pre-suckling calcium supplementation effectively prevents lactation-induced osteopenia in rats. Am J Physiol Endocrinol Metab 2014; 306:E177-88. [PMID: 24302005 DOI: 10.1152/ajpendo.00556.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
During lactation, osteoclast-mediated bone resorption and intestinal calcium hyperabsorption help provide extra calcium for lactogenesis. Since the suckling-induced surge of pituitary prolactin (PRL) rapidly stimulates calcium absorption in lactating rats, it is hypothesized that pre-suckling oral calcium supplementation should be an efficient regimen to shift the calcium source from bone to diet, thereby slowing lactation-induced osteopenia. Our results showed that 30-min suckling markedly stimulated maternal duodenal calcium transport, which returned to the baseline at 45 min. Lactating rats given 4 mg/kg per dose calcium via a gavage tube at 90 min pre-suckling 4 doses a day for 14 days prevented a decrease in bone mineral density (BMD) of long bones and vertebrae. On the other hand, a single-dose supplementation, despite the same amount of calcium per day, appeared less effective. Because glucose and galactose further stimulated duodenal calcium transport in lactating rats, pre-suckling calcium supplement containing both sugars successfully normalized plasma ionized calcium and led to better bone gain than that with calcium alone. A histomorphometric study revealed that lactating rats given pre-suckling calcium plus monosaccharide supplement manifested greater trabecular bone volume and thickness and exhibited less eroded surface than in vehicle-treated lactating rats. Beneficial effects of the 14-day calcium supplementation persisted until 6 mo postweaning in dams and also elevated the baseline BMD of the offspring. In conclusion, our proof-of-concept study has corroborated that pre-suckling calcium supplements, especially regimens containing monosaccharides, are efficient in preventing osteopenia in lactating rats and could increase bone density in both breastfeeding mothers and neonates.
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Affiliation(s)
- Panan Suntornsaratoon
- Center of Calcium and Bone Research (COCAB Faculty of Science, Mahidol University, Bangkok, Thailand
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10
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Suntornsaratoon P, Wongdee K, Tiyasatkulkovit W, Ampawong S, Krishnamra N, Kengkoom K, Charoenphandhu N. Defective bone microstructure in hydronephrotic mice: a histomorphometric study in ICR/Mlac-hydro mice. Anat Rec (Hoboken) 2013; 297:208-14. [PMID: 24227694 DOI: 10.1002/ar.22836] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/16/2013] [Indexed: 11/08/2022]
Abstract
Chronic renal impairment can lead to bone deterioration and abnormal bone morphology, but whether hydronephrosis is associated with bone loss remains unclear. Herein, we aimed to use computer-assisted bone histomorphometric technique to investigate microstructural bone changes in Imprinting Control Region (ICR) mice with a spontaneous mutation that was associated with bilateral nonobstructive hydronephrosis (ICR/Mlac-hydro). The results showed that 8-week-old ICR/Mlac-hydro mice manifested decreases in trabecular bone number and thickness, and an increased trabecular separation, thereby leading to a reduction in trabecular bone volume compared with the wild-type mice. Furthermore, histomorphometric parameters related to both bone resorption and formation, that is, eroded surface, osteoclast surface, and osteoblast surface, were much lower in ICR/Mlac-hydro mice than in the wild type. A decrease in moment of inertia was found in ICR/Mlac-hydro mice, indicating a decrease in bone strength. In conclusion, ICR/Mlac-hydro mice exhibited trabecular bone loss, presumably caused by marked decreases in both osteoblast and osteoclast activities, which together reflected abnormally low bone turnover. Thus, this mouse strain appeared to be a valuable model for studying the hydronephrosis-associated bone disease.
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Affiliation(s)
- Panan Suntornsaratoon
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Thailand
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11
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Rievaj J, Pan W, Cordat E, Alexander RT. The Na⁺/H⁺ exchanger isoform 3 is required for active paracellular and transcellular Ca²⁺ transport across murine cecum. Am J Physiol Gastrointest Liver Physiol 2013; 305:G303-13. [PMID: 23764894 PMCID: PMC4959879 DOI: 10.1152/ajpgi.00490.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal calcium (Ca²⁺) absorption occurs via paracellular and transcellular pathways. Although the transcellular route has been extensively studied, mechanisms mediating paracellular absorption are largely unexplored. Unlike passive diffusion, secondarily active paracellular Ca²⁺ uptake occurs against an electrochemical gradient with water flux providing the driving force. Water movement is dictated by concentration differences that are largely determined by Na⁺ fluxes. Consequently, we hypothesized that Na⁺ absorption mediates Ca²⁺ flux. NHE3 is central to intestinal Na⁺ absorption. NHE3 knockout mice (NHE3-/-) display impaired intestinal Na⁺, water, and Ca²⁺ absorption. However, the mechanism mediating this latter abnormality is not clear. To investigate this, we used Ussing chambers to measure net Ca²⁺ absorption across different segments of wild-type mouse intestine. The cecum was the only segment with net Ca²⁺ absorption. Quantitative RT-PCR measurements revealed cecal expression of all genes implicated in intestinal Ca²⁺ absorption, including NHE3. We therefore employed this segment for further studies. Inhibition of NHE3 with 100 μM 5-(N-ethyl-N-isopropyl) amiloride decreased luminal-to-serosal and increased serosal-to-luminal Ca²⁺ flux. NHE3-/- mice had a >60% decrease in luminal-to-serosal Ca²⁺ flux. Ussing chambers experiments under altered voltage clamps (-25, 0, +25 mV) showed decreased transcellular and secondarily active paracellular Ca²⁺ absorption in NHE3-/- mice relative to wild-type animals. Consistent with this, cecal Trpv6 expression was diminished in NHE3-/- mice. Together these results implicate NHE3 in intestinal Ca(2+) absorption and support the theory that this is, at least partially, due to the role of NHE3 in Na⁺ and water absorption.
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Affiliation(s)
- Juraj Rievaj
- Dept. of Pediatrics, 4-585 Edmonton Clinic Health Academy, 11405 87th Ave., Univ. of Alberta, Edmonton, Alberta, T6G 2R7, Canada.
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