NEUROCHEMICAL MECHANISM OF BEHAVIORAL REACTIONS FORMATION UNDER CONDITIONS OF EMOTIONAL LOAD IN EARLY ONTOGENESIS

Abstract

Background. Emotional overload is accompanied by a neurotransmitter imbalance during ontogenesis, the specifics of which are poorly defined. The relationship between changes in neurotransmitters in the cerebral cortex and hippocampus with changes in behavioral and cognitive activity in juvenile rats requires detailed investigation.

Aim- to study of the neurotransmitter mechanism of the adaptive response formation of the juvenile rat brain under the conditions of moderate and excessive emotional overload.

Materials and methods. Acute and chronic stress were simulated in an open water space. The study of innate and acquired behavior was carried out in an elevated pluse maze, the number of enters into the dark arms, the number of stands, the duration of grooming (s) were recorded, and in the Morris water maze - the latent period of finding the rescue stand (s) was determined. Chromatographically determined the content of neurotransmitter compounds (GABA, glutamate, glycine) and serotonin in the cerebral cortex and hippocampus. Mathematical processing included calculations of arithmetic mean values (M), standard deviations (SD), and Pearson's correlation analysis.

Results. A study of the spontaneous behavior of juvenile rats with moderate overload showed a decrease in the number of enters into the dark arms by 53% and the number of stands by 79% (p<0.05), an increase in the duration of uncomfortable grooming by 33% (p<0.05) compared to the control. In the rats of the "excessive overload" group, the number of enters into the dark arms decreased by 45% and the number of racks by 74% (p<0.05) compared to the control condition. The latent period of finding the rescue stand in experimental juvenile animals of the "moderate overload" group was reduced by 55% (p<0.05), and in animals of the "excessive overload" group by 53% (p<0.05) compared to the control. Correlation analysis showed that a decrease in motor activity under conditions of moderate overload is associated with the content of glycine in the neocortex and with the number of enters into the dark arms, and there is also a connection between glutamate and glycine in the hippocampus with racks. The enhancement of grooming, which also occurred under the influence of moderate overload, was correlated with the content of serotonin in the hippocampus.

Conclusions. The formation of the acquired adaptive protective reaction under conditions of moderate overload occurred with the participation of an increase in glutamatergic and a decrease in glycinergic activity of the hippocampus. Under conditions of excessive overload, correlations between the content of neurotransmitters and the latent period of the protective reaction in the Morris maze have not been established.