Affiliations: Department of Nutritional Science, Faculty of Applied
Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku,
Tokyo 156-8502, Japan | Department of Nutrition, Junior college of Tokyo
University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502,
Japan
Abstract: To determine the parathyroid hormone (PTH) action on kidney and bone
by high phosphorus (P) diet, this study investigated PTH/PTH-related peptide
(PTHrP) receptor mRNA expression in 6-week-old parathyroidectomized (PTX) rats
received constant amount of PTH. To maintain serum PTH levels equally to sham
operated rats, PTX rats were constantly exposed to rPTH (1–34) and fed a
control diet (0.3% P) and a high P diet (1.2% P) for 7 days, respectively.
There were no significant differences in serum PTH (1–34) concentration in
rats fed the control diet. In sham groups, serum PTH concentrations, both
(1–84) and (1–34) fragments, were increased in rats fed the high P diet than
in rats fed the control diet. Urinary excretions of P and C-terminal
telopeptides of type I collagen were significantly increased in both PTX and
sham rats by the high P diet. PTH/PTHrP receptor mRNA expression in kidney and
femur was not changed in both PTX and sham rats by the high P diet. In
conclusion, high P diet did not change PTH action in PTX rats and increased
urinary excretion of P and bone resorption regardless of PTH action.
Keywords: high phosphorus diet, PTH action, PTH/PTHrP receptor mRNA, parathyroidectomized rat
Journal: BioFactors, vol. 22, no. 1-4, pp. 33-37, 2004
