Smetaniuk O. Age aspects of the structural and functional state of the large cell nuclei of the hypothalamus under stress

The thesis is devoted to the age-related aspects of the structural and functional state of the large-cell hypothalamic nuclei under stress-induced influences. The thesis establishes the morphological basis for the regularities of age-related chronorhythmic organization of the supreme center of coordination of autonomic functions – paraventricular and suprachiasmatic nuclei of hypothalamus depending on the photoperiod modifications, which is necessary for studying the central mechanisms of circadian rhythms of the brain. The reasonability of melatonin application (1.0 mg/kg of animal body weight) for 7 days under light stress was shown, which led to an increase in compensatory-adaptive transformations, restoration of circadian rhythm of diurnal dynamics with a tendency to normalization of 1A melatonin receptor density indicators and morphofunctional activity in the supraoptic nucleus of the hypothalamus of aged rats. When melatonin was applied against the background of prolonged illumination, the number of neurons positively stained for 1A melatonin receptors was 0.412±0.0025 AU at 2 a.m. and 0.324±0.0027 AU at 2 p.m. respectively and was close to that of the control group of old rats. Practical significance of the obtained results. The results of the experimental studies expand the idea of the morphological basis of the mechanisms of chrononeuroendocrine integration in the formation of circadian rhythms and, in particular, the participation in them of neuroendocrine transducers – lateral large-cell and medial small-cell subnuclei of the paraventricular nuclei and large-cell neurosecretory cells of the hypothalamic supraoptic nuclei of old rats. New fundamental data on melatonin receptor density and structural transformations of peripheral components of the system regulating diurnal rhythms and adaptation under light exposure have been obtained, which may form the basis for the development of new approaches and principles of prevention and treatment of desynchronosis associated with 24-hour light. The results are advisable to consider in the process of teaching pathological histology, cytology, physiology, hygiene and ecology. The scientific validity of using melatonin for the correction of morphofunctional and immunohistochemical disorders of the subpopulations of the paraventricular and supraoptic nuclei of the hypothalamus of old animals under light stress has been scientifically proved.