The Effect Of Alendronate On The Expression Of Osteopontin In Calcified Aortic Tissue Of The Rat

Objective: The present experiments were carried out to study the effect of alendronate on the expression of OPN in rat calcified aortic tissue of vascular calcification model treated with warfarin and vitamin D3 , and explore possible mechanism of inhibiting artery calcification by alendronate.Methods: All 5-weeks old male SD rats were randomly divided into 3 groups: the control group(n=20), calcification group(n=20) and alendronate group (n=20). The latter two groups were subcutaneously injected with warfarin (15mg/ 100g per 12 hours for 4 days) and 1,25-dihydroxyvitamin D3 (vitaminD3 300000U/kg per day for 3 days) to induce extensive calcification of the aorta. Alendronate group was treated with daily subcutaneously injection of alendronate beginning 4 days before the first warfarin dose. The control group was given daily subcutaneous injection of normal saline. All injections were administered subcutaneously into the backs of the animals. All rats received doses of 1.5 mg vitamin K1 per 100 g of body weight for preventing bleeding on 2 days before the first warfarin dose, then mineral deposition was assessed by Von Kossa staining, RT-PCR was performed for OPN mRNA, Immunohistochemistry was performed for OPN protein expression. Calcium content was measured by using an atomic absorption spectrophotometer.Results: Von kossa staining showed no calcification can be detected in untreated control animals., there were strongly positively-stained black areas in calcification group, and less calcification in alendronate group than calcification group. OPNmRNA in calcification group was significantly reduced as compared with those in control group(0.0681±0.019 vs 0.2506±0.014,p<0.05), OPNmRNA in alendronate group was increased significantly compared with those in calcification group(0.2173±0.012 vs 0.0681±0.019, p<0.05). Immunohistochemical staining demonstrated that mean optical density of OPN was decreased in calcification group as compared with control group(0.3188±0.026 vs 0.7523±0.074, p<0.05), and significantly increased in alendronate group as compared with calcification group( 0.5751±0.022 vs 0.3188±0.026, p<0.05). Calcium content in rat aorta was significantly increased in calcification group as compared with control group(1.4131±0.021 vs 0.6197±0.094, p<0.05), and significantly decreased in alendronate group as compared with calcification group(0.8023±0.079 vs 1.4131±0.021, p<0.05).Conclusions:Alendronate could inhibit significantly the artery tunica media calcification through increasing the expression of OPN...