BONE MINERAL DENSITY OF THE RATS TIBIA AFTER MODELING OF ARTIFICIAL MENOPAUSE AND INFLUENCE OF WHOLE BODY VIBRATION
Authors: Kostyshyn N. М. 
Published: July 2021

Early deficiency of female sex hormones provokes bone loss in various parts of the skeleton, which further requires therapeutic correction. However, it is known that vibrational oscillations are anabolic for the trabecular layer of bone, which have been studied in both animal models and humans under physiological norms. It is likely that this anabolic reaction does not occur evenly throughout the skeleton, on the one hand, due to the cushioning properties of muscle tissue, ligaments, joints, and resonance, on the other.

The aim of the study is to assess the condition and mineral density of the tibia under the condition of artificial menopause and the influence of non-physiological whole body vibration (WBV) with acceleration 0,3 g.

Material and methods. The experiments were performed on 54 adult female Wistar rats. Rats were divided into three groups: control group (n=18) – SHAM surgery, experimental group I (n=18) - rats with ovariectomy, experimental group II (n=18) - rats after ovariectomy + WBV. Rats of were subjected to total vibration with acceleration of 0,3 g for 30 minutes 5 days a week for 24 weeks. At the 8th, 16th and 24th week of the experiment CT-densitometry of the tibia was performed.

Results. The greatest loss of bone tissue was observed in experimental group I at the 24th week of the experiment, which decreased by 23.5% compared with the control group. At the 8th week of the study, the rate did not change statistically, and at the 16th - decreased to 8.1%. In experimental group II, bone density did not decrease statistically at the 8th and 16th week of our study, however, at the 24th week decreased by -16% to the control group, and compared with group I, increased by +11,2 % on the 24th day. The cortical layer of the tibial bone tissue did not change statistically in the experimental groups in relation to the control group. Factors that can affect the anabolic response in the tissues of the musculoskeletal system are the parameters of vibration, in particular the frequency and level of vibration acceleration. In our experimental study, we observed a decrease in bone mineral density in rats with ovariectomy and compared with ovariectomized rats subjected to vibration. We observed a positive correlation between whole body vibration and bone mass increase, which may be due to the effect of increased mechanical stress on the skeleton. We also demonstrated the negative effect of time after ovariectomy on bone density in experimental rats. The use of vibration maintained normal bone mineral density for a long time, and until the 16th week of the experiment, but at the 24th week, rate decreased significantly compared with the control group, but was higher than in group I. Analysis of CT scans showed high values of mineral density in experimental group II (ovariectomy + WBV) compared with experimental group I.

Conclusions. The obtained results allow us to conclude that the WBV inhibits the accelerated remodeling after ovariectomy and prevents the rapid loss of bone tissue for a long time. To this end, mechanical vibrations should be used in the early menopause to maintain normal bone mineral mass. This therapy can be used alone and as an adjunct to osteoporosis medication. Therefore, early detection of osteopenia and timely appropriate treatment is important, which, in addition to antiresorptive drug treatment, should include lifestyle changes and exercise.