Bone metabolism and formation of mice bred in a 2G environment

Kita, Satomi; Iwasaki, Katsurô; Onishi, Reizo; Fujisawa, Mihoko; Kim, H.; Shibata, Shigeki; Ito, Masao

doi:10.1016/s0273-1177(03)90380-2

Cited by 7 publications

(2 citation statements)

References 2 publications

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“…ICR mice are a strain tolerant to hypergravity and can be passage-bred in a 2G environment (16,28). We examined the effects of hypergravity on Cyp24a1 and Cyp27b1 expression in C57BL/6J mice.…”

Section: Ajp-endocrinol Metabmentioning

confidence: 99%

Hypergravity modulates vitamin D receptor target gene mRNA expression in mice

Ishizawa

Iwasaki²,

Kato³

et al. 2009

American Journal of Physiology-Endocrinology and Metabolism

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The possibility of pathological calcium metabolism is a critical health concern introduced by long-term space travel. Because vitamin D plays an important role in calcium homeostasis, we evaluated the effects of hypergravity on the expression of genes involved in vitamin D and calcium metabolism in ICR mice. When exposed to 2G hypergravity for 2 days, the mRNA expression of renal 25-hydroxyvitamin D 24-hydroxylase (Cyp24a1) was increased and that of 25-hydroxyvitamin D 1␣-hydroxylase (Cyp27b1) was decreased. Although hypergravity decreased food intake and increased the expression of starvation-induced genes, the changes in Cyp24a1 and Cyp27b1 expression were not due to starvation, suggesting that hypergravity affects these genes directly. Hypergravity decreased plasma 1␣,25-dihydroxyvitamin D3 levels in ICR mice, suggesting a consequence of decreased Cyp27b1 and increased Cyp24a1 expression. Although 1␣-hydroxyvitamin D3 [1␣(OH)D3] treatment induced the expression of vitamin D receptor (VDR) target genes in the kidney of 2G-exposed ICR mice to similar levels as controls, 1␣(OH)D3 increased the intestinal expression of Cyp24a1 in ICR mice. Hypergravity-dependent changes of Cyp24a1 and Cyp27b1 expression were diminished in mice exposed to hypergravity for 14 days, which may represent an adaptation to hypergravity stress. Hypergravity exposure also increased Cyp24a1 expression in the kidney of C57BL/6J mice. We examined the effects of hypergravity on VDRnull mice and found that renal Cyp27b1 expression in VDR-null mice was decreased by hypergravity while renal Cyp24a1 expression was not detected in VDR-null mice. Thus hypergravity modifies the expression of genes involved in vitamin D metabolism. 12), and vitamin D 2 is less effective than vitamin D 3 in maintaining serum 25(OH)D levels (1). Vitamin D deficiency, mainly caused by inadequate sun exposure, results in rickets and osteomalacia, and is also associated with increased risk of cancer, autoimmune disease, infection, and cardiovascular disease (10). 1,25(OH) 2 D 3 exhibits physiological and pharmacological effects by binding to the vitamin D receptor (VDR; NR1I1), a transcription factor of the nuclear receptor superfamily, which is highly expressed in the target organs of calcium homeostasis, such as the intestine, bone, kidney, and parathyroid glands (6, 21). VDR regulates the expression of many target genes, including 25-hydroxyvitamin D 24-hydroxylase (CYP24A1), calbindin D9k, and transient receptor potential vanilloid type 6 (TRPV6).Bone mineral loss is one of the critical health concerns raised by the prospect of long-term space travel (19,29). Space flight induces uncoupled bone remodeling, including increased bone resorption and urinary calcium excretion and decreased calcium absorption. Vitamin D deficiency due to the absence of ultraviolet light and decreased dietary intake of vitamin D during space flight has been considered to be one reason for dysregulated bone and calcium metabolism (30). Supplemental vitamin D and calcium intake increase blood...

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Section: Ajp-endocrinol Metabmentioning

confidence: 99%

Hypergravity modulates vitamin D receptor target gene mRNA expression in mice

Ishizawa

Iwasaki²,

Kato³

et al. 2009

American Journal of Physiology-Endocrinology and Metabolism

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“…Moreover, they cannot hang on a horizontal bar with both hands. There are reports that mechanical stimulation such as weight-bearing is crucial for bone growth [34][35][36]. When a child with congenital terminal transverse carpal deficiency uses the affected limb less frequently, this may, therefore, result in insufficient forearm growth.…”

Section: Discussionmentioning

confidence: 99%

Difference between affected and unaffected sides of forearm bone length in children with congenital terminal transverse deficiencies at the level of carpal bone

Nishizaka

Fujiwara

Mano

et al. 2022

Journal of Pediatric Orthopaedics B

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The forearm of the affected sideis often shorter than that of the unaffected side in children with congenital terminal transverse deficiencies at the level of proximal or distal carpals. The aim of this study is to clarify the characteristics of forearm bone length in those children, especially to quantify the difference in forearm bone length between affected and unaffected sides. The subjects were children with carpal partial transverse deficiencies. The lengths of the radius and the ulna were measured in the radiographs. The lengths of affected and unaffected sides (A/U) were compared in order to quantify the discrepancy. The A/U ratio was defined as the length of the affected side divided by that of the unaffected side. The A/U ratios ranged from 77.1 to 99.0% in the radii and from 74.1 to 99.6% in the ulnae. In both the radius and ulna, the A/U ratios were significantly lower than the left/right ratios of normal adults. Additionally, the A/U ratios of the ulna were significantly lower than the A/U ratios of the radius. The forearm bones of affected side are significantly shorter than those of unaffected side. Although the cause remains unclear, it is possible that not only congenital factors but also acquired factors such as infrequent use of the affected upper limb are involved. A future longitudinal study is necessary to investigate whether length discrepancies can be reduced by using prostheses to increase the frequency of use on the affected limb.

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Animal Development in Microgravity

Horn

Fundamentals of Space Biology

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Bone metabolism and formation of mice bred in a 2G environment

Cited by 7 publications

References 2 publications

Hypergravity modulates vitamin D receptor target gene mRNA expression in mice

Hypergravity modulates vitamin D receptor target gene mRNA expression in mice

Difference between affected and unaffected sides of forearm bone length in children with congenital terminal transverse deficiencies at the level of carpal bone

Animal Development in Microgravity

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