Is vitamin D indispensable for Ca2+ homeostasis: lessons from knockout mouse models?

“…A series of studies has generated sometimes conflicting data on the effects on Ca 2+ homeostasis and absorption in knockouts for VDR, 51–55 25‐hydroxyvitamin D 3 ‐1α‐hydroxylase, 56–59 calbindin‐D 9k , 60–62 calbindin‐D 28k , 60 TRPV6, 63–65 and combinations thereof 60,64 . Critical analyses of subsets of these papers identified differences in absorption protocols as a key issue 1,8,11 …”

Section: Gene Knockout Studiesmentioning

confidence: 99%

“…A variety of dietary regimens have been designed in attempts to augment mineral absorption in patients with chronically impaired absorption. Accordingly, there have been many excellent reviews of the physiological and nutritional significance of intestinal Ca 2+ absorption 1–24 …”

Section: Introductionmentioning

confidence: 99%

Alternative perspective on intestinal calcium absorption: proposed complementary actions of Cav1.3 and TRPV6

Kellett

2011

Nutrition Reviews

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Transcellular models of dietary Ca(2+) absorption by the intestine assign essential roles to TRPV6 and calbindin-D(9K) . However, studies with gene-knockout mice challenge this view. Something fundamental is missing. The L-type channel Ca(v) 1.3 is located in the apical membrane from the duodenum to the ileum. In perfused rat jejunum in vivo and in Caco-2 cells, Ca(v) 1.3 mediates sodium glucose transporter 1 (SGLT1)-dependent and prolactin-induced active, transcellular Ca(2+) absorption, respectively. TRPV6 is activated by hyperpolarization and is vitamin D dependent; in contrast, Ca(v) 1.3 is activated by depolarization and is independent of calbindin-D(9K) and vitamin D. This review considers evidence supporting the idea that Ca(v) 1.3 and TRPV6 have complementary roles in the regulation of intestinal Ca(2+) absorption as depolarization and repolarization of the apical membrane occur during and between digestive periods, respectively, and as chyme moves from one intestinal segment to another and food transit times increase. Reassessment of current arguments for paracellular flow reveals that key phenomena have alternative explanations within the integrated Ca(v) 1.3/TRPV6 view of transcellular Ca(2+) absorption.

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“…Vitamin D, considered a steroid prohormone rather than a classic vitamin, take part a crucial role in calcium and phosphate homeostasis (Boisen et al, 2017;Lerchbaum & Obermayer-Pietsch, 2012). The metabolic pathway of vitamin D is strictly regulated, via 1 α hydroxylase enzyme, by parathormone, calcitonin, calcium and sex steroids (Hoenderop & Bindels, 2005). Vitamin D manifests its biological effects through calcium-binding proteins by binding to vitamin D receptors (VDR) in skeleton, parathyroid gland and reproductive tissues, and its biological inactivation is catabolised by calcitroic acid with 24 hydroxylase enzymes (Holick, 2007).…”

Section: Introductionmentioning

confidence: 99%

Investigation of serum vitamin D and ischaemia‐modified albumin levels in infertile Turkish men

İnal¹,

İnal²,

Mermer³

et al. 2020

Andrologia

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Our aim was to explore the existence of a possible relationship of sperm motility with serum 25‐hydroxyvitamin D3 (25‐OH VD) levels and with ischaemia‐modified albumin (IMA) levels in infertile Turkish men. A total of 30 men with nonobstructive azoospermia (no spermatozoa in ejaculate), 30 men with oligospermia (total progressive motile sperm count (TPMSC) <15 × 106/ml) and 33 fertile men with normospermia (with at least one child, as the control group) were enrolled in the study. The mean 25‐OH VD levels for groups 1, 2 and 3 were 9.31 ± 6.46, 19.71 ± 12.80 and 30.52 ± 12.49 respectively (p < .05). There was a statistically significant difference in serum IMA levels among the groups (479.32 ± 307.56 vs. 296.37 ± 127.27 vs. 150.04 ± 81.05, respectively; p < .05). A positive correlation between serum 25‐OH VD levels and TPMSC, and a negative correlation between TPMSC and serum IMA levels were determined. Infertile men had lower serum 25‐OH VD and higher IMA levels than fertile men, with a positive correlation between serum 25‐OH VD levels and TPMSC, and a negative correlation between TPMSC and serum IMA levels. Vitamin D supplementation may increase the sperm motility.

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Is vitamin D indispensable for Ca2+ homeostasis: lessons from knockout mouse models?

Cited by 9 publications

References 22 publications

Vestibular dysfunction in vitamin D receptor mutant mice

Vestibular dysfunction in vitamin D receptor mutant mice

Alternative perspective on intestinal calcium absorption: proposed complementary actions of Cav1.3 and TRPV6

Investigation of serum vitamin D and ischaemia‐modified albumin levels in infertile Turkish men

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