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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2003-1-30
pubmed:abstractText
A group of growing dogs supplemented with cholecalciferol (vitamin D(3); HVitD) was studied vs. a control group (CVitD; 54,000 vs. 470 IU vitamin D(3)/kg diet, respectively) from 3 to 21 wk of age. There were no differences in plasma levels of P(i) and growth-regulating hormones between groups and no signs of vitamin D(3) intoxication in HVitD. For the duration of the study in HVitD vs. CVitD, plasma 25-hydroxycholecalciferol levels increased 30- to 75-fold; plasma 24,25-dihydroxycholecalciferol levels increased 12- to 16-fold and were accompanied by increased renal 24-hydroxylase gene expression, indicating increased renal 24-hydroxylase activity. Although the synthesis of 1,25-dihydroxycholecalciferol [1,25(OH)(2)D(3)] was increased in HVitD vs. CVitD (demonstrated by [(3)H]1,25(OH)(2)D(3) and increased renal 1alpha-hydroxylase gene expression), plasma 1,25(OH)(2)D(3) levels decreased by 40% as a result of the even more increased metabolic clearance of 1,25(OH)(2)D(3) (demonstrated by [(3)H]1,25(OH)(2)D(3) and increased gene expression of intestinal and renal 24-hydroxylase). A shift of the Ca set point for parathyroid hormone to the left indicated increased sensitivity of the chief cells. Effective counterbalance was provided by hypoparathyroidism, hypercalcitoninism, and the key regulator 24-hydroxylase, preventing the development of vitamin D(3) toxicosis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0193-1849
pubmed:author
pubmed:issnType
Print
pubmed:volume
284
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
E505-13
pubmed:dateRevised
2008-8-16
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
24-Hydroxylase: potential key regulator in hypervitaminosis D3 in growing dogs.
pubmed:affiliation
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands. M.A.Tryfonidou@vet.uu.nl
pubmed:publicationType
Journal Article