The article summarizes information on the basic characteristics associated with the genetically determined level of excitability of the nervous system, as well as long-term stable changes in behavior, morphological, genetic and epigenetic modifications caused by long-term emotional and painful stress in the cells of various brain structures in rats of the НT (high threshold, low-excitable ) and LT (low threshold, high- excitable) strains, selected for threshold of excitability of the nervous system to the electric current. Over this long research period, the rats of these strains have been manifesting differences not only in tibial nerve excitability, but also in the thresholds of excitability in other parts of the nervous system, both the peripheral and CNS. The impact of the nervous system excitability on a wide spectrum of unconditioned and conditioned behavioral characteristics has been revealed. In these rat strains, alterations have been detected in various parts of hormonal regulation systems, neurotransmission, the ion channels functioning, structural and functional properties of the nerve cell membranes. Strains have manifested different stress-reactivity in tests of sleep deprivation, response to short and long-term emotional-painful stress. Prolonged post-stress behavioral manifestations persist for six months in the both HT and LT rats. Disorders of higher nervous activity have strain-specific manifestations: formation of a depressive-like behavior in the low-excitable HT strain, an increase in excitability, aggression, the disturbance of plastic processes, and an increase in stereotypic behavior in the highly excitable LT strain. These characteristics allow the usage of these strains as model objects for studies on the post-stress anxiety disorders, in particular, post-traumatic stress disorder and compulsive disorder. The long-term effects of stress are based on the morphological changes of neurons in various brain structures, differential chromatin modifications in neurons and other somatic cells associated with epigenetic DNA and histone modifications. The horizons of using the HT and LT strains for the elucidating genetic and epigenetic mechanisms of dysadaptation in response to environmental factors in terms of a personified medicine with a glance on the nervous system excitability are discussed.
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