Effects of excessive aluminum on osteoclasts and expression of mRNA related with bone metabolism in C57BL/6 mice / 中华地方病学杂志

ABSTRACT

Objective To investigate the effects of excessive aluminum on osteoclastic formation and function in C57BL/6 mice.Methods Six-week-old male C57BL/6 mice (n =20) were randomized by weight and divided into control group and treatment group.The mice were assigned to distilled water and 270 mg/L aluminum ion,respectively.After the 15-week treatment period,the mice were euthanized by ether asphyxiation.Concentration of serum aluminum ion was determined by inductively coupled plasma (ICP).TRAP+ cells in vivo were observed using histomorphometry and osteoclasts microstructure using electron microscope (TEM).Osteoclasts were induced by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL) with bone marrow macrophages separated from femur and tibia.The expression of mRNA related with bone resorption was detected,including c-FBJ osteosarcoma oncogene (c-Fos),nuclear factor of activated T-cells cl (NFATc1),c-nonreceptor tyrosine kinase (c-Src),dentrocyte expressed seven transmembrane protein (DC-STAMP),d2 isoform of vacuolar (H1) ATPase v0 domain (ATP6v0d2) and matrix metalloproteinase 9 (MMP-9).Results The data showed that the treatment group [(12.04 ± 0.21)mg/L] had significantly increased serum aluminum ion compared with the control group [(11.00 ± 0.04)mg/L,F =10.286,P ＜ 0.05].TRAP+ cells examination confirmed osteoclasts in treatment group [(31.39 ± 9.80) number] were significantly higher than those in the control group [(5.46 ± 4.15) number,F =9.344,P ＜ 0.05].A large proportion of osteoclasts in treatment group lacked ruffled borders and showed vacuolation degeneration.The expression of mRNA in treatment group was lower than that of the control group.The expression of mRNA in control group and treatment group was NFATcl (3.25 ± 0.93 vs.0.29 ± 0.18,F =11.602,P ＜ 0.05),c-Fos (0.86 ± 0.16 vs.0.16 ± 0.02,F =9.405,P ＜ 0.05),c-Src (8.82 ± 1.51 vs.2.29 ± 0.36,F =9.128,P ＜ 0.05),DC-STAMP (3.70 ± 0.70 vs.1.36 ± 0.57,F =10.298,P ＜ 0.05),ATP6v0d2 (15.60 ± 4.81 vs.1.39 ± 0.95,F =8.828,P ＜ 0.05),and MMP-9 (18.64 ± 7.62 vs.2.10 ± 0.92,F =9.356,P ＜ 0.05),respectively.Conclusions Aluminum can increase the number of osteoclasts under epiphyseal plate,but inhibits osteoclasts differentiation.This phenomena may be related with decreased expression of c-Src,DC-STAMP,c-Fos,NFATcl,ATP6v0d2 and MMP-9 mRNA which regulate the function of osteoclasts.