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Interactions between the total blood calcium level and catecholamine contents in limbic brain structures during the formation and extinction of a conditioned passive avoidance reflex were studied in rats with hypoparathyroidism. Impairments of calcium support for the processes of conditioned reflex activity were seen after removal of the parathyroid glands. Animals with hypoparathyroidism not only showed changes in basal dopamine and noradrenaline levels in limbic structures, but also impairments of catecholamine dynamics during the acquisition and forced extinction of a conditioned passive avoidance reflex. These results demonstrate changes in the functional dynamics of the dopaminergic and noradrenergic systems of the brain in conditions of abnormal calcium homeostasis in the body, which underlie abnormalities of conditioned reflex activity and the acquisition of the adaptive behavioral strategies.

CardiovasCular adaptations of foreign students to ClimatiC and geographiCal Conditions of stavropol regiona b s t r a c t -Purpose of research: studying adaptive opportunities of the cardiovascular system of foreign students to the climatic and geographical conditions of Stavropol region. Methods: The data sample included the Stavropol and foreign students, natives of the countries of the Southern Asia, the Western Asia and Africa in the youthful period of ontogenesis and the first period of a maturity. In total 218 students, from them the Russian students were examined: youths -73 persons, men -55 people; foreign students: youths -36 people, men -54 persons. Results: Stable and compensatory adaptive reactions are characteristic to youths and men from the Southern Asia and to men from the Western Asia. A condition of the critical tension (excessive tension) are characteristic to firstyear students and senior students from Africa. Findings: It is established that the greatest stress of adaptation mechanisms is experienced by students from Africa. K E y w o r d s -adaptation, mathematical analysis of the heart rhythm, variational pulsometry, foreign students, Stavropol region.

Aim. The article aims to evaluate the functional status of the hypothalamic-pituitary-adrenocortical and hypothalamic-pituitary-gonadal systems in females with vascular dystonia from a special medical group. Materials and methods. The study involved first-year female students divided into 3 groups: 1 (control, n = 45) – apparently healthy students; 2 (experimental, n = 27) – students from a special medical group with vascular dystonia (VVD): 1st experimental (n = 12) – students diagnosed with VVD of the hypertensive type, 2nd experimental (n = 15) – students with VVD of the hypotonic type. The functional status of the hypothalamic-pituitaryadrenocortical and hypothalamic-pituitary-gonadal systems was revealed by the concentration of cortisol (K), testosterone (T) and estradiol (E) in saliva and the E / T ratio. Results. The content of cortisol in saliva in females with VVD in both experimental groups was significantly higher (P < 0.001, P < 0.05) than in the control group. Cortisol levels are higher in females with hypertensive VVD than in females with hypotonic VVD (P < 0.05). In females with VVD of the hypotonic type, the level of estradiol is higher by 24% than in the control group, and in females with VVD of the hypertensive type, estradiol is more than twice higher. The concentration of testosterone was significantly higher in both experimental groups compared to the control group (P < 0.001), an increase in T was observed in females with VVD of the hypertensive type. The E/T ratio in students with VVD in both groups showed no significant changes compared to the control group. Significant positive differences were revealed in females with VVD of the hypertensive type compared with VVD of the hypotonic type (P < 0.01). Conclusion. The results of the study showed that changes in hormone secretion can be considered as a chain of closely connected reactions in the regulatory mechanisms of the cardiovascular system for maintaining self-regulation of the body and ensuring adaptation under stress. Therefore, the disruption of any link requires the use of reserve capacities of the body, which affects the performance of the leading adaptation systems.