The Effects of Electrical Stimulation on Loss of Bone Mass in the Ovariectomized Rat

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Abstract

In osteoporosis treatment, current interventions suffer from challenges of guaranteed efficacy for patients. Electrical stimulation has been shown to improve bone mass in animal models of disuse, but there have been no studies of the effects of electrical stimulation on bone loss in a hormone deficiency model. The purpose of this study was to explore the effects of electrical stimulation on bone mass in the ovariectomized (OVX) rat model.

We developed a custom electrical stimulation device capable of delivering a constant current, 15 Hz sinusoidal signal. We used 30 female Sprague Dawley rats (12-13 weeks old). Half were OVX, and half underwent sham OVX surgery (SHAM). These rats were divided into baseline, stimulation (stim), and no-stimulation (no-stim) groups. Stimulation groups received transdermal electrical stimulation to the right knee, while the left knee served as a non-stimulated contralateral control. The no-stimulation groups had electrodes placed on the right knee, but not connected. Rats underwent the procedure for one hour per day for six weeks. Rats were sacrificed (CO2) after six weeks. Femurs and tibias were scanned by microCT. MicroCT data were analyzed for trabecular and cortical bone measures.

Femurs and tibias from OVX rats had significantly less trabecular bone than SHAM. In the distal femur of OVX-stim rats, bone volume fraction was significantly greater in the stimulated right than the non-stimulated contralateral (left). There were no differences between stim and no-stim groups for tibial trabecular measures, or cortical bone measures in either the femur or the tibia.

This study presents novel findings that electrical stimulation can partially mitigate bone loss in the OVX rat femur, a model of human post-menopausal bone loss. Further work is needed to explore why there was a differential response of the tibial and femoral bone, and to better understand how bone cells respond to electrical stimulation.

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