Currently the age-related changes in the intensity of lipid peroxidation and its controlling systems are considered to be one of the main causes of membrane damage and cell death. In addition, the basic functions of the body are regulated and coordinated by the endocrine system. In the process of aging, the functional activity of adrenal cortex, thyroid and genital glands is significantly weakened. Extreme rhythmic cold exposures activate the hypothalamic-pituitary-adrenal system, which determines the severity of adaptive responses in case of homeostasis disorders. However, despite a high therapeutic effectiveness of extreme cooling, in some cases its use in elderly people is accompanied by the occurrence of side effects. In connection with the foregoing, the purpose of the study was to assess the intensity of lipid peroxidation in brain tissue and the content of hormones in blood serum of aged rats before and after applying various rhythmic extreme cooling regimens. Material and methods. Studies were performed in white aged (26-30-month-old) outbred male rats. Animals were divided into four groups: the 1st group included intact rats; the 2nd group had aged rats after 9 sessions of rhythmic extreme cold exposures (RECE) at temperatures (–120°С; –120°С; –120°С); the 3rd group comprised aged animals with a combined use of different temperature regimens of RECE (–60°С; –120°С; –120°С); and the 4th group encompassed aged animals after 9 sessions of RECE at temperatures (–60°С; –60°С; –60°С). Extreme rhythmic cold exposures were performed in a metrologically certified cryochamber for cooling of experimental animals. Animals of all groups were removed from the experiment by decapitation after the 9th cooling procedure, as well as a week and a month after the last cooling procedure, and brain tissue and blood serum were taken for biochemical studies. Results and discussion. In the course of experimental studies, we found out that the temperature regimen of extreme rhythmic cooling (–60°С; –120°С; –120°С) at the initial stages of observation increased the intensity of lipid peroxidation in brain tissues of aged rats, while in contrast to the regimen (–120°С; –120°С; –120°С), a month after the last cooling procedure, it activated the antioxidant system. The use of extreme cooling especially under temperature conditions (–120°C; –120°C; –120°C) and (–60°C; –120°C; –120°C) led to a stable stimulation of the thyroid, adrenal and reproductive systems of aged rats, thereby significantly increasing the activity of functional systems of an aging body. Conclusion. Thus, the temperature regimen of cooling (–60°C; –120°C; –120°C) turned out to be the most optimal for aged animals, since its use was accompanied by normalization of the pro-oxidant-antioxidant balance in brain tissues, as well as a stable stimulation of the thyroid, adrenal and reproductive systems.
Keywords: lipid peroxidation, malondialdehyde, endocrine system, extreme rhythmic cold exposures, hormones
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