COMBINED EFFECT OF CORTISOL AND TESTOSTERONE ON ADAPTATIVE BEHAVIOUR STRATEGY IN OPEN FIELD

Objective. The aim of the study is to examine the combined effect of cortisol and testosterone on animal adaptation in the open field, taking into account their constitutional characteristics. Materials and Methods. The authors examined behavioural entropy of 20 adult male Wistar rats. Behavioral entropy is calculated using a special formula based on the parameter fixed during testing according to I.Yu. Zbrodin methodology. It allows us to assess the probability of certain behavior acts used by animal based on individual coping strategies. The experiment included recording defecation and urination rates, which are defined by many researchers as an external manifestation of emotional stress. Upon the experiment completion, blood was collected to assess the cortisol and testosterone levels. Blood test was carried out using the enzyme immunoassay on an Immelite DPS Cirrus Inc. analyzer. Correlation analysis was used for quantitative characteristics of agreement rates. Results. During the experiment, a constitutionally given characteristic, namely the entropy of rat behavior, was determined. The complex nature of adaptation in a stressful environment is manifested through various coping strategies used by animals. Adaptation is accompanied by tension in the endocrine system, various manifestation of vegetative reactions. Cortisol contributes to stress development, increasing the concentration of glucose in the blood, determining the strategy of body adaptation to stressful environment. Testosterone, being cortisol antagonist reduces its effectiveness, and acts as one of the components of the stress-limiting system. Conclusion. Cortisol concentration is connected with certain behaviour acts, which characterize two different coping strategies - limited use of behaviour acts (low behavioral entropy) and, on the contrary, active perception under general strategy of search activity (high behavioral entropy). The functional antagonism of cortisol and testosterone against the background of variable receptor binding makes it possible to consider the ratio of these hormones as a marker of eustress.