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Bone resorption and serum levels of vitamin D metabolites in the hypophosphataemic rat
Author(s) -
Malcolm Alan,
Reynolds Eric
Publication year - 1997
Publication title -
australian dental journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 71
eISSN - 1834-7819
pISSN - 0045-0421
DOI - 10.1111/j.1834-7819.1997.tb00107.x
Subject(s) - weanling , medicine , endocrinology , phosphate , resorption , chemistry , metabolite , vitamin d and neurology , calcium , intraperitoneal injection , vitamin , bone resorption , biochemistry
The supplementation of a low phosphate diet with vitamin D has been shown to result in an increase in bone resorption in the hypophosphataemic rat. The aim of the present study was to determine if administration of vitamin D to rats fed a vitamin D and phosphate‐depleted diet would result in an increase in the circulatory levels of the active vitamin D metabolite 1,25(OH) 2 D 3 and an associated increase in bone resorption. Three groups of weanling Sprague‐Dawley rats were used. The first group consisted of control animals on a normal laboratory stock diet and the second and third groups were experimental animals receiving a vitamin D‐and phosphate‐deficient diet with the third group receiving vitamin D supplementation. All animals were housed in the dark. After 30 days on the diet the experimental animals received 0.1 mmol NaH 2 PO 4 by intraperitoneal injection. Blood was sampled at zero, 3, 6, 18 and 48 h post‐injection and analysed for the vitamin D metabolites 25(OH)D 3 and 1,25(OH) 2 D 3 , calcium and inorganic phosphate (Pi). The serum analyses revealed that the level of 25(OH)D 3 in the hypophosphataemic animals was significantly lower than that of the control animals. However the 1,25(OH) 3 D 3 level was initially significantly higher, then dropped to the control level at 18 h post‐intraperitoneal injection of phosphate. Further, the serum levels of 25(OH)D 3 and 1,25(OH) 2 D 3 , calcium and Pi in the hypophosphataemic animals supplemented with vitamin D were significantly higher than those of the vitamin D‐deficient animals. Also the vitamin D‐supplemented animals exhibited significantly greater levels of bone resorption. These results therefore, are consistent with a role of 1,25(OH) 2 D 3 in bone resorption in hypophosphataemic rats.