The Role of the Hippocampus in the Neuroendocrine Response to Neurobiological Stimuli in Experiment.

We compared the levels of functional activity of cells in each adrenal zone with blood levels of corticosterone, testosterone, and neuropeptide Y in control and hippocampectomized F1(C57BL/6×DBA/2) mice during modeling of metabolic, motivational, and cognitive tension. The morphofunctional state of the adrenal glands was studied using a new morphometric approach. It was found that hippocampectomy changed the testosterone response to neurobiological stimuli; similar changes were observed in the zona reticularis of the adrenal cortex producing dehydroepiandrosterone that is involved in the regulation of testosterone secretion. At the same time, hippocampectomy enhanced the response of the peptide hormone; the index of functional activity of chromaffin cells producing this hormone also increased. These findings allow us to put forward a hypothesis that the hippocampus is involved in the regulation of mutual influences of the studied hormones and that it modulates the sensitivity of testosterone and NPY to metabolic and cognitive factors.

The Cost of Adaptation to Information Loading in Mice with Various Genetic Profiles.

It was found that male BALB/c and F1(C57BL/6×DBA/2) mice are able to recognize the structure of a complex food-gathering task, when modeling the information loading similar to intellectual work in humans. There were significant differences between linear and hybrid animals in the pattern of learning process formation and prevailing psychoemotional reactions that accompany information load. Factors of information loading (uncertainty of maze environment and solution of the food-gathering task) had a specific influence on the CNS and manifested in individual non-specific features. The presented experimental conditions (changes in the metabolic and functional state) revealed pronounced intergroup differences in the reaction of the functional zones of the adrenal cortex. In hybrid mice, information loading induced a significant decrease in testosterone level and thickness of the zona reticularis producing precursor hormones. This is probably due to disruption of interactions in the adrenal-thyroid system in hybrid mice, whereas in BALB/c mice, these interactions fully protect from suppression of testosterone production, the main anabolic hormone. The individual characteristics of the response to information loading can be formed as a result of unequal involvement of the psychophysiological, psychological, and autonomic systems responsible for adaptation to environmental factors.

"Behavior" of the Hormonal Ensemble through the Prism of Cluster Analysis.

The serum hormone concentrations were studied in a group of male F1 (C57BL/6×DBA/2) mice in different states of food activity (satiety, 24-h food deprivation, and cognitive load against the background of food deprivation). The hormonal response depended on food activity: the content of leptin, triiodothyronine, and testosterone decreased in hungry animals, while during cognitive load (learning), we observed a decrease in the concentrations of ghrelin, leptin, thyroxine, and testosterone. The exceptions were neuropeptide Y (its concentration increased in hungry animals) and corticosterone (its level remained unchanged). The use of hierarchical cluster analysis allowed identifying functional organization of the relationships within the hormonal ensemble that underwent plastic changes depending on the state of the organism. It was shown that the hormonal ensemble was system-organized in the form of a "core" that determines stability of the system and the "field", within which functional interactions of the hormones are preserved.

[Psychophysiological signs of aging in mice F1 (C57BL/6×DBA/2).]

The psychophysiological effects of aging in mice of the line F1 (C57BL/6×DBA/2) at the age of 3, 7, and 14 months were investigated. It was found that the cognitive abilities, memory and spatial orientation in all animals did not depend on age, they were able to form a 4-link food-getting habit. The instability of behavior found in all mice at the stereotyped stage of in the form of periodic reproduction of false and irrational realizations was determined by the peculiarities of the basic nervous processes - increased excitability and weakness of inhibition. It was possible to establish that the consistent reduction of the excitation phase during the aging process caused the instability of the dominant state and motivational activity, negatively affecting the attention stable and, consequently, the ability to consistently reproduce the optimal variant of habit.