Calcimimetic NPS R-568 prevents parathyroid hyperplasia in rats with severe secondary hyperparathyroidism.
Calcimimetic NPS R-568 prevents parathyroid hyperplasia in rats with severe secondary hyperparathyroidism.


BACKGROUND
Secondary hyperparathyroidism (secondary HPT) in chronic renal insufficiency (CRI) is characterized by multiglandular hyperplasia.


METHODS
In this study, we investigated the effects of the calcimimetic NPS R-568 on the parathyroid gland in rats with CRI induced by ligation of the renal arteries and severe secondary HPT induced by dietary phosphorus loading. Six days after surgery, high-phosphorus diet feeding was started, and NPS R-568 was administered to the rats for 56 days either by daily gavage (30 or 100 micromol/kg) or by continuous subcutaneous infusion (20 micromol/kg. day).


RESULTS
After 54 days, serum PTH levels in vehicle-treated CRI rats were 1019 vs. 104 pg/mL in sham-operated controls. Infusion of NPS R-568 maintained serum PTH at levels comparable with those of sham-operated controls, whereas daily gavage also prevented much of the increase in CRI controls and decreased PTH levels intermittently in a dose-dependent fashion. Parathyroid gland enlargement was caused predominantly by hyperplasia. Total cell number per kg body wt was 3.5-fold higher in vehicle-treated CRI rats than in sham-operated controls. Both infusion and high-dose gavage of NPS R-568 completely prevented the increase in parathyroid cell number.


CONCLUSIONS
These results demonstrate that the calcimimetic compound NPS R-568 can prevent both the increase in serum PTH levels and parathyroid hyperplasia in rats with CRI and severe secondary HPT. Moreover, these changes occurred despite decreases in serum 1, 25(OH)2D3 and increases in serum phosphate, suggesting a dominant role for the calcium receptor in regulating parathyroid cell proliferation.
Wada
M
M
Pharmaceutical Development Laboratory, Kirin Brewery Co; Ltd, Gunma, Japan.
Nagano
N
N
Furuya
Y
Y
Chin
J
J
Nemeth
E F
EF
Fox
J
J
D000814:Aniline Compounds / Q000494:pharmacology*; D000818:Animals; D001806:Blood Urea Nitrogen; D001835:Body Weight; D002118:Calcium / Q000097:blood; D006962:Hyperparathyroidism, Secondary / Q000150:complications*; D006965:Hyperplasia; D008297:Male; D010279:Parathyroid Diseases / Q000209:etiology / Q000517:prevention & control*; D010281:Parathyroid Hormone / Q000097:blood; D010627:Phenethylamines; D011437:Propylamines; D051381:Rats; D017207:Rats, Sprague-Dawley
D000814:Aniline Compounds; C107873:N-(2-chlorophenylpropyl)-1-(3-methoxyphenyl)ethylamine; D010281:Parathyroid Hormone; D010627:Phenethylamines; D011437:Propylamines; D002118:Calcium