The effect of parathyroid hormone on expression of matrix GLA protein in ovariectomized SD rats and primary osteoblasts / 中华内分泌代谢杂志

ABSTRACT

ObjectiveTo observe the effect of parathyroid hormone on expression of matrix GLA protein (MGP) in ovariectomized SD rats and primary osteoblast,and to study the role of MGP on the possible mechanism of postmenopausal osteoporosis.MethodsThirty-six Sprague-Dawley female rats were allocated into 3 groups,12 in eachsham operation group,ovariectomized group( OVX group),ovariectomized and parathyroid hormone treatment group.Animals in the parathyroid hormone group were injected parathyroid hormone (20 μg/kg,three times a week for 12 weeks) three weeks after ovariectomy.All rats were sacrificed after 18 weeks.Urine and serum were collected every three weeks.Lumbar vertebral bones were observed by immunohistochemistry.Bone mineral density (BMD) of lumbar vertebra of rats was determined.The content of MGP in serum and urine was determined by enzyme-linked immunosorbent assay (ELISA).Expression of undercarboxylated Matrix GLA Protein (ucMGP) was detected by immunochistochemistry.Relative quantification of MGP mRNA expression in lumbar vertebra bone was detected by Fluorescent real-time quantitative polymerause chain reaction.Results ( 1 ) 18 weeks after ovariectomy,BMD of lumbar vertebra in OVX group was lower than those in sham group and parathyroid hormone group significantly ( P＜0.05 ).(2) The content of MGP in serum and urine was dynamic variation after treatment hy parathyroid hormone,and it was significant compared with OVX group ( P＜0.05 ).( 3 ) Immunohistochemical localization of ucMGP was seen in lumbar vertebra in OVX group.(4) Relative quantification of MGP mRNA expression in lumbar vertebra in OVX group was increased significantly compared with other groups ( P＜0.01 ).( 5 ) parathyroid hormone ( 1-34 ) in 10-7mol/L,10-8mol/L,10-9 mol/L up-regulated MGP mRNA expression in primary osteoblasts about 6.78,5.31,and 2.23 times than control respectively.It was in a dose-dependent manner.ConclusionThe effect of parathyroid hormone on the expression of matrix gla protein may play an important role in mechanism of postmenopausal osteoporosis