Introduction. Menopause is an important risk factor for osteoporosis in people of all ages. Deficiency of female sex hormones and decrease in bone mineral density can be observed in young people, such as congenital ovarian pathology or their surgical removal. It is known that exercise has a positive effect on the human health, and it is important to prevent the loss of bone mass. A number of studies indicate that the effects of mechanical stress in such individuals enhance the physiological reactions of bone adaptation. Therefore, regular exercise has a positive effect on bone tissue, slowing down the loss of mineral mass. Aim. Investigate the possibility of the influence of non-physiological mechanical stimuli on the condition and mineral density of the tibia during premature menopause. Materials and methods. Vibration was chosen as a form of non-physiological mechanical stimulation, because its beneficial effect can be easily applied to humans in the form of exercises. We evaluated the effect of mechanical stimulation, in the form of whole body vibration with a low level of vibration acceleration (frequency: 50 Hz, amplitude 1.2 mm, 0.3 g, 30 min / day for 5 days / week), on the prevention of loss of tibial mineral mass in postmenopausal osteoporosis in rats model. The experiment lasted 24 weeks. We used X-ray diffraction analysis to assess bone loss and determine the structure of nanocomposites. Determination of calcium content was performed by atomic absorption spectrophotometry. Results. In groups of ovariectomized rats, a statistically significant (p<0.05) decrease in the mineral component of the tibia was recorded at the 8th week after ovariectomy. This effect persisted during the 24-week study. It was experimentally investigated that whole body vibration prevented the early loss of mineral mass after ovariectomy at 8-16 weeks. Rats with ovariectomy, which were exposed to vibration, showed statistically significantly higher (p<0.05) values of the crystalline component compared to their control group during the same period of time. Although the vibration had a positive effect on bone tissue in rats, after ovariectomy at 8–16 weeks, at 24 weeks this effect was not statistically significant. Our data suggest that nonphysiological vertical mechanical oscillations are an effective means of preventing early post-ovariectomy bone loss in an animal model. At the 8th week of the experiment, we observed a decrease in calcium levels in the samples of the first and second experimental groups, but the results were statistically insignificant (p>0.05). At the 16th and 24th week of observations, the mass of calcium decreased in the first experimental group, which is statistically significant (p<0.05). Probably, this indicates the continuation of bone remodeling and the activity of osteoclasts and osteoblasts during the experiment and leads to a loss of mineral mass of the tibia. It should be noted that the loss of calcium under the influence of high-frequency vibration decreased significantly from the 16th week (p<0.05) and up to the 24th week of the experiment (p<0.05). Conclusions. Mechanical oscillations with low levels of vibration acceleration, slows bone remodeling in young rats after ovariectomy. This does not lead to acute bone damage in the early periods, and, subsequently, slows down the loss of mineral components. Our data suggest that nonphysiological vertical mechanical oscillations are an effective means of preventing early post-ovariectomy bone loss in an animal model. The described vibrational effects may be useful for understanding bone metabolism under different living conditions for the prevention and adjunction in the treatment of osteopenia in various pathologies, in particular postmenopause.
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