Nutritional secondary hyperparathyroidism in rabbits.
The present study was designed to document the effect of a low (0.6%) calcium-high (1.2%) phosphorus (LCaHP) diet on the development of parathyroid gland hyperplasia in rabbits and to describe the dynamics of parathyroid function (PTH-Ca2+ curves) in rabbits with nutritional secondary hyperparathyroidism (N2HPT). Parathyroid gland weight, parathyroid cell proliferation (measured as percentage of cells in S-phase), and parathyroid calcium (CaRmRNA) and Vitamin D (VDRmRNA) receptor expression were measured in normal rabbits and in rabbits with N2HPT. The PTH-Ca2+ curve was studied in normal rabbits (Group I) and in rabbits with N2HPT at two stages: 2-3 weeks (Group IIA) and 5-6 weeks (Group IIB) after being fed LCaHP diet. An increase in parathyroid gland weight and percentage of cells in S-phase was detected in the course of N2HPT. After receiving a LCaHP diet for 6 weeks rabbits had decreased levels of CaRmRNA but VDRmRNA remained unchanged. A progressive increase in the concentrations of plasma PTH (Group IIA=167+/-14 pg/ml and Group IIB=377+/-54 pg/ml, P<0.05 versus Group I=27+/-3 pg/ml) was detected in the rabbits fed a LCaHP diet. This was accompanied by an increase in maximal and minimal PTH, reductions in plasma Ca2+ and calcitriol and elevations in plasma phosphate and creatinine. In conclusion, feeding a LCaHPD results in a rapid induction of N2HPT in rabbits. After 6 weeks on the LCaHPD rabbits develop parathyroid hyperplasia characterized by increases in PTH secretion, glandular weight and proliferation and by a decrease in CaRmRNA.
Bas
Sonia
S
Dept. Medicina y Cirugía Animal, Universidad de Córdoba, Campus Universitario de Rabanales, Ctra. Madrid-Cádiz km 396, 14014 Córdoba, Spain.
Bas
Alicia
A
López
Ignacio
I
Estepa
José C
JC
Rodríguez
Mariano
M
Aguilera-Tejero
Escolástico
E
D000818:Animals; D002117:Calcitriol / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003404:Creatinine / Q000097:blood; D005260:Female; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000378:metabolism / Q000662:veterinary*; D008297:Male; D009752:Nutritional Status / Q000502:physiology*; D009929:Organ Size; D010280:Parathyroid Glands / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D016226:Phosphorus, Dietary / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D011817:Rabbits / Q000378:metabolism*; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D044169:Receptors, Calcium-Sensing / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D010710:Phosphates; D016226:Phosphorus, Dietary; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D044169:Receptors, Calcium-Sensing; D003404:Creatinine; D002117:Calcitriol