Effects of pulsed electromagnetic fields on histomorphometry and osteocalcin in disuse osteoporosis rats

OBJECTIVE: Bone histomorphometry and the concentration of the serum osteocalcin expression were observed in disuse osteoporosis (DOP) rats in order to explore the mechanism of pulsed electromagnetic fields in treating DOP. METHODS: Female SD rats, weighing 250 ∼ 280 g, were randomly divided into 4 groups: a control group and three experimental groups. The right hindlimbs of all the rats were immobilized by tibia-tail fixation, except for those in the INT group. The ALN group rats were given an alendronate sodium (1 mg kg-1 d-1) treatment, and the rats in the PEMF group received PEMF irradiation. Bone histomorphometry and the concentration of serum osteocalcin expression were detected in 2, 4, 8, and 12 weeks. RESULTS: Four weeks after modeling, as compared with the DOP group, the %Tb-Ar and Tb-N in the ALN group were increased, and the difference was significant (P< 0.05 or P< 0.01). At 8 weeks, as compared with the DOP group, the %Tb-Ar and Tb-N in the ALN group and the PEMF group both increased, and there was a significant difference (P< 0.05 or P< 0.01). At 12 weeks, as compared with the DOP group, the BGP serum concentration of the ALN group was reduced, and there was a statistical difference (P< 0.05). CONCLUSION: Pulse electromagnetic field with drug can prevent disuse osteoporosis by changing the bone microstructure. In the long run, PEMF improves the mechanical performance of biological structures better than alendronate sodium does. PEMF may influence the process of bone remodeling by promoting the level of osteocalcin.