The influence of a pulsed magnetic field on the expression of runt-related transcription factor 2 in rats after ovary resection

Abstract

Objective To observe the influence of a pulsating electromagnetic field (PEMF) on the expression of runt-related transcription factor 2 (Runx2) in ovariectomized rats so as to explore the possibility of using PEMFs to treat osteoporosis. Methods Sixty female Sprague-Dawley rats were randomly divided into four groups of 15-a control group (Sham group), an ovary resection group (OVX group), a resection group treated with alendronate sodium (OVX+ ALN group) and a resection group exposed to a PEMF (PEMFs group). Both ovaries were resected to induce osteoporosis, except in the sham group where the adipose tissues around the ovaries were cut bilaterally without resection. After the operation, the ALN group were given 2 mg/kg of alendronate by gavage daily for 30 days, while the PEMFs group was exposed to a 3.8 mT electromagnetic field pulsing at 8 Hz for 40 min twice daily for 30 days. There was no intervention in the other two groups. The animals were sacrificed using intra-peritoneal injection of sodium pentobarbital and the density of their femurs was measured. The expression of Runx2 protein and Runx2 mRNA were detected using western blotting and quantitative PCR. Results The average bone density, Runx2 protein level and Runx2 mRNA level of the PEMFs group were all significantly higher than those of the OVX group, but there was no significant difference between the PEMFs group and ALN group averages. Conclusion PEMF exposure can upregulate the expression of Runx2 protein and Runx2 mRNA in female rats after ovary resection. This may be one of the mechanisms by which PEMFs treat osteoporosis. Key words: Osteoporosis; Pulsed electromagnetic fields; Runx2 gene