The effect of prolonged emotional and pain stress on the expression of the bdnf gene in the brain of rats with contrast excitability of the nervous system

BACKGROUND: The neurotrophic factor BDNF performs important functions in synaptic plasticity and functional activity of neurons, involve in the stress response and the pathogenesis of post-stress disorders. The specificity of post-stress changes in the bdnf mRNA level due to genetically determined features of excitability of the nervous system has not been studied. AIM: To study the level of bdnf mRNA in the prefrontal cortex, hippocampus and amygdala of rats of two strains with contrasting excitability of the nervous system in normal condition and at different times after prolonged emotional and painful stress exposure (after 24 hours, 7, 24, 60 days). MATERIALS AND METHODS: The study was carried out on adult male rats of two strains with a different level of excitability of the nervous system (HT high threshold and LT low threshold of excitability). As a model of chronic stress, a long-term emotional and painful exposure according to Hecht was used. The bdnf mRNA level was determined using quantitative real-time PCR. Changes in the level of bdnf mRNA in the prefrontal cortex, hippocampus and amygdala of control and experimental groups of rats of two strains were studied at different time points (24 hours, 7, 24 days, 2 months) after prolonged emotional and painful stress exposure. RESULTS: It was found that in highly excitable LT rats, a decrease in the expression of the bdnf gene in the prefrontal cortex occurs 24 hours and persists up to 7 days after exposure, in the hippocampus 2 months after exposure. In rats of the low-excitable HT strain, the decrease in bdnf mRNA was not detected. CONCLUSIONS: In highly excitable LT rats, prolonged emotional and painful stress causes a decrease in the expression of the bdnf gene in the prefrontal cortex and hippocampus. In low-excitable rats of the HT strain, no significant decrease in the mRNA level of this neurotrophin was found in any of the studied brain regions. The possible association of this specificity of changes in the level of bdnf mRNA with a greater severity of post-stress anxiety-like behavior disorders in highly excitable rats compared with low-excitable ones is discussed.