Zamors'ka T. The research of the exogenous melatonin and altered partial pressure of oxygen influence on indices of bone tissue remodeling

Dissertation is devoted to the research of peculiarities physiological bone tissue remodeling regulation under exogenous melatonin and altered partial pressure of oxygen influence. The study has shown that oral introduction of exogenous melatonin at a dose of 1 mg/kg in a period of minimum of its daily synthesis in the organism enhances the physiological remodeling processes of young rats’ bone tissue. Exogenous melatonin does not cause significant changes of reconstruction indices of adult rats’ bone tissue, possibly due to a more stable regulation of remodeling processes. The results of the second experimental series allow us to focus on the fact that dosed normobaric hypoxia activates the cellular elements of bone tissue that are responsible for remodeling processes. This influence allows to keep the balance of the functional activity of osteoblasts and osteoclasts, without breaking the physiological equilibrium of remodeling processes of bone tissue. We consider that the higher stimulating effect was achieved when using the principle of intermittent normabaric hypoxia at a ratio regime of hypoxygenation-reoxygenation 1:3. The obtained values of indices of remodeling of different ages rats’ bone tissue suggest that breathing air with a high oxygen content (40% O2) for 1 hour daily does not cause significant changes in the researched indices. This corresponds to the safe level of oxygen concentration in the gaseous medium that is prescribed in clinical medicine. Staying of young rats at higher concentrations of oxygen (90% O2) during 14 one-hour daily sessions was accompanied by probable changes in the researched indices, that indicates the substantial deregulation of processes of bone tissue formation and resorption. The obtained results may have not only theoretical values but also present some practical application in maintaining or activation of physiological regeneration of bone tissue, which tends to the development of osteopenia and osteoporosis in low physiological stress.