Study on Pulsed Electromagnetic Fields Regulate the mRNA Expression of V-ATPase, CAII, NFAT2 and RANK in an Ovariectomized Rat Model of Osteoporosis Mechanism Analysis

Abstract

We investigated the mRNA expression of V-ATPase CA II, NFAT2, and RANK as well as bone mineral density (BMD) in bilaterally ovariectomized (OVX) rats treated with pulsed electromagnetic fields (PEMF), to explore the mechanism by which PEMF alter bone at the molecular level in vivo. 24 Sprague–Dawley female rats were randomly divided into three different groups: SHAM, OVX, ovariectomy with PEMF stimulation (PEMF+OVX). The PEMF frequency was 3.8 mT, 8 Hz, for 40 min per day. Eight rats in each group were treated for 28 days. At the end of the intervention, the body weight and BMD were measured. The mRNA expression of V-ATPase, CA II, NFAT2 and RANK were analyzed by real-time fluorescent-nested quantitative polymerase chain reaction (RT-PCR). The V-ATPase, CAII, NFAT2 and RANK genes show strong expression in the OVX group as compared with the SHAM group (P<0.001, respectively). The mRNAs expression of V-ATPase, CAII, NFAT2 and RANK in PEMF treatment group were significantly lower than that in OVX group, respectively (p=0.001, p=0.000, p=0.013, P=0.04, respectively). The V-ATPase, CAII and RANK mRNA expression in the PEMF+OVX group were higher than SHAM group (p=0.04, p=0.001, p=0.000, respectively). However, the NFAT2 mRNA expression did not show a statistically significant difference between the SHAM and the PEMF+OVX group (P=0.08). This study indicated that exposure to PEMF restrained bone resorption in order to elevate BMD, and this outcome occurred in part through RANK-signaling by the CN/NFAT pathway to regulate bone metabolism. Alternatively, PEMF may promote the BMD through regulating the expression of NFAT2 genes. It may have certain significance in the treatment target of osteoporosis.