alexa Alteration in bone metabolism with increasing age: effects of zinc and vitamin D3 in aged rats.


Vitamins & Minerals

Author(s): Yamaguchi M, Ozaki K, Suketa Y

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Abstract The alteration in bone metabolism with increasing age was investigated in the femoral diaphysis of male rats. Calcium content was highest in the bone from 3-week-old rats (491 +/- 13 mg/g bone ash), falling gradually with aged to 357 +/- 7 and 306 +/- 9 mg/g bone ash in 28- and 52-week-old rats, respectively. Bone zinc content increased until rats were 3 weeks of age, and thereafter remained constant. Deoxyribonucleic acid (DNA) content was highest in the bone from 1-week-old rats, and it decreased markedly with increasing age. Alkaline phosphatase and acid phosphatase activities increased up to 3 weeks, then subsequently declined with age. Thus, the retardation of bone metabolism was induced by ageing. When zinc sulfate (5.0, 10.0 and 20.0 mg Zn/kg body weight) was administered orally for 3 d to 28-week-old rats, alkaline phosphatase activity and calcium content in the femoral diaphysis was elevated markedly by all doses. The oral administration of vitamin D3 (2.0 and 20 micrograms/kg) for 3 d in 28-week-old rats did not produce an appreciable increase in bone alkaline phosphatase activity or calcium content, while 1,25-dihydroxyvitamin D3 (1.5 micrograms/kg) caused a significant increase in those biochemical indices. These results indicate that zinc and 1,25-dihydroxyvitamin D3 play a role as activators in bone metabolism of ageing rats.
This article was published in J Pharmacobiodyn and referenced in Vitamins & Minerals

Relevant Expert PPTs

Relevant Speaker PPTs

  • Yosef Yarden
    Classically, the 3’untranslated region (3’UTR) is that region in eukaryotic protein-coding genes from the translation termination codon to the polyA signal. It is transcribed as an integral part of the mRNA encoded by the gene. However, there exists another kind of RNA, which consists of the 3’UTR alone, without all other elements in mRNA such as 5’UTR and coding region. The importance of independent 3’UTR RNA (referred as I3’UTR) was prompted by results of artificially introducing such RNA species into malignant mammalian cells. Since 1991, we found that the middle part of the 3’UTR of the human nuclear factor for interleukin-6 (NF-IL6) or C/EBP gene exerted tumor suppression effect in vivo. Our subsequent studies showed that transfection of C/EBP 3’UTR led to down-regulation of several genes favorable for malignancy and to up-regulation of some genes favorable for phenotypic reversion. Also, it was shown that the sequences near the termini of the C/EBP 3’UTR were important for its tumor suppression activity. Then, the C/EBP 3’UTR was found to directly inhibit the phosphorylation activity of protein kinase CPKC in SMMC-7721, a hepatocarcinoma cell line. Recently, an AU-rich region in the C/EBP 3’UTR was found also to be responsible for its tumor suppression. Recently we have also found evidence that the independent C/EBP 3’UTR RNA is actually exists in human tissues, such as fetal liver and heart, pregnant uterus, senescent fibroblasts etc. Through 1990’s to 2000’s, world scientists found several 3’UTR RNAs that functioned as artificial independent RNAs in cancer cells and resulted in tumor suppression. Interestingly, majority of genes for these RNAs have promoter-like structures in their 3’UTR regions, although the existence of their transcribed products as independent 3’UTR RNAs is still to be confirmed. Our studies indicate that the independent 3’UTR RNA is a novel non-coding RNA species whose function should be the regulation not of the expression of their original mRNA, but of some essential life activities of the cell as a whole.
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