Effect of four different anti-osteoporosis agents on the expression of matrix gla protein in primary osteoblasts of SD rat

Abstract

Objective To observe the expression of matrix gla protein(MGP) mRNA in primary osteoblasts of Sprague-Dawley (SD) rat in vitro after treatment with anti-osteoporosis agents [vitamin K2,PTH,1,25 (OH)2D3,and alendronate],and to investigate the potential role of MGP in the pathogenesis of osteoporosis.Methods Primary osteoblasts(OBs) were derived from sequential trypsin/collagenase-digested calvaria isolated from newborn SD rat (postnastal day 1-3).OBs of the second generation were identified by Van Gieson collagen staining,alkaline phosphatase(ALP) staining and calcified nodules staining.OBs of the fourth generation were selected to interfere with vitamin K2,PTH,1,25 (OH)2D3,and alendronate,then cultured for 24 h in mediums which contained various concentrations of vitamin K2 (10-7,10-6,and 10-5 mol/L),PTH (10-9,10-8,and 10-7 mol/L),1,25 (OH) 2D3(10-10,10-9,and 10-8mol/L),alendronate(10-6,10-5,and 10-4mol/L).After being cultured for 24 h,total RNA was extracted and examined by real-time quantitative RT-PCR.Results The primary cultured cells had typical morphological characters of osteoblast.van Gieson collagen staining,ALP staining,and calcified nodules staining were all positive.Vitamin K2,PTH,1,25 (OH)2D3,and alendronate could modulate the expression of MGP mRNA in osteoblasts in a dose-dependent fashion.MGP mRNA expressions were 2.56-fold,2.12-fold,and 1.57-fold with 10-5,10-6,and 10-7 mol/L of vitamin K2 treatment,respectively.The expressions were 6.78-fold,5.31-fold,and 2.23-fold with 10-7,10-8,and 10-9mol/L of PTH(1-34) treatment,8.93-fold,6.95-fold,and 3.47-fold with 10-8 10-9,and 10-10mol/L of 1,25 (OH)2D3 treatment,and 3.47-fold,2.49-fold,and 1.98-fold with 10-4,10-5,and 10-6mol/L of alendronate treatment.Conclusion Vitamin K2,PTH,1,25 (OH)2D3,and alendronate all can regulate MGP mRNA expression in calvarial osteoblasts in a dose-dependent manner.MGP seems to be a potent target of anti-osteoporosis agents,and involved in the pathogenesis of osteoporosis. Key words: Osteoporosis drugs; Matrix gla protein; Rats,Sprague-Dawley; Osteoblasts