Effect of ferri ion and estradiol on bone mass and bone formation

Abstract

Objective To explore the effect of iron on bone formation with or without estradiol. Methods 8-week old female ICR mice 25±1 g were randomly divided into 3 groups (n=7 each): SHAM group, OVX group and F+OVX group, which were intervened by ferric ammonium citrate (FAC) with a dose of 0.10 g/kg per week. After 8 weeks, the mice of OVX group and F+OVX group were spayed (with ovariotomy). 12 weeks later, body weight, serum ferritin were measured. The expression changes of Runx2, Osterix, Bglap, OPG, ER-α, ER-β derived from mice tibiae were detected by RT-PCR. A high resolution Micro-CT was used to scan the femur. Primary osteoblasts, extracted from suckling mice's cranium, were intervened by FAC and estradiol. Harvested cells after 24 h, then operated alkaline phosphatase staining and q-PCR. Gene expressions of Runx2, osterix and Bglap were measured. Results There were no significant difference between every group in body weight The serum Fer was heightened in F+OVX group (324.82±38.60 μg/L) comparing with SHAM group (39.40±3.81 μg/L) and OVX group (41.38±5.56 μg/L). The differences were statistically significant among the three groups. BMD of OVX group (0.114±0.013 mg/mm3) was lower than that of SHAM group (0.297±0.072 mg/mm3), but higher than that of F+OVX group (0.902±0.064 mg/mm3), The differences were statistically significant among the three groups. RT-PCR results: The expressions of OPG, Runx2, osterix, Bglap and ER-β were decreased after ovariotomy, while the level of osterix and OPG dropped further with the treatment of FAC. In vitro experiment, results of ALP staining suggested that FAC decrease the level of ALP. Q-PCR showed that the expressions of Runx2, osterix were reduced by FAC, while estradiol increased Bglap expression. Conclusion Iron accumulation might have further result in inhibition of bone formation and suppression of osteogenic activity without estradiol. Key words: Estradiol; Osteoporosis; Osteoblasts