RESUMO
Stress plays an important role in the pathogenesis of anxiety and depressive disorders. Neuroinflammation is considered as one of the mechanisms by which stress alters the molecular and cellular plasticity in the nervous tissue and thus entails CNS dysfunction. The contribution of genetically determined features of the nervous system to the development of post-stress neuroinflammation has not been sufficiently studied. In this study, the dynamics of post-stress changes in mRNA levels of the il-1ß and tnf genes encoding proinflammatory cytokines interleukin-1 beta (IL-1ß) and tumor necrosis factor (TNF) were evaluated in the blood and brain of two rat strains with high and low excitability thresholds of the nervous system (HT and LT, respectively). Changes in IL-1ß and TNF mRNA levels were assessed by real-time PCR 24 h, 7, 24 and 60 days after long-term long-term emotional and painful stress in the blood and three brain structures involved in the development of post-stress pathology (prefrontal cortex, hippocampus, amygdala). In highly excitable LT rats, IL-1ß mRNA level in the hippocampus and amygdala increased compared to the control 24 days after stress termination, while in low-excitable HT animals, an increase in the level of IL-1ß mRNA was only detected in the hippocampus at the same time point. TNF mRNA level did not change in any of the rat strains at any of the post-stress time points. Genetically determined excitability of the nervous system is a promising marker of individual stress vulnerability, as manifested in post-stress disorders associated with developmental and time-course features of neuroinflammation.
RESUMO
Patients with post-stress pathologies display the signs of inflammation in the peripheral blood as well as in the brain. The mechanisms of such post-stress neuroimmune changes, their contribution to the behavior, the relationship of the intensity of inflammation with genetically determined features have not been clarified. The goal of this work was to evaluate the dynamics of post-stress inflammation in the blood and hippocampus of rats which differ in level of excitability of the nervous system. Rats of two strains (high/low excitability threshold) were subjected to stress according to the K. Hecht protocol and their behavior, neutrophil:lymphocyte ratio and the number of Iba+ cells in the hippocampus were analysed 24 hours, 7 and 24 days after stress exposure. Highly excitable animals show an increase in anxiety-like behavior, in the number of neutrophils compared to lymphocytes as well as in the number of Iba1+ cells in CA1, CA3 and DG areas of the hippocampus in response to stress. Thus, hereditary high excitability of the nervous system is a possible risk factor for the development of post-stress pathologies.
Assuntos
Hipocampo , Neurônios , Estresse Psicológico , Animais , Masculino , RatosRESUMO
We performed immunohistochemical analysis of the expression of caspases 3, 9 and bcl-2 protein in rat brain at various terms after administration of LD50 of sodium thiopental. Expression of the specified apoptosis markers was found in the sensorimotor cortex and hippocampus (dentate gyrus and CA2 region).
Assuntos
Encéfalo/metabolismo , Caspase 3/metabolismo , Caspase 9/metabolismo , Coma/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Animais , Apoptose/fisiologia , Encéfalo/enzimologia , Giro Denteado/metabolismo , Hipocampo/metabolismo , Imuno-Histoquímica , Masculino , RatosRESUMO
There is a continued interest in the research of epigenetic mechanisms of genes regulation in the brain, associated with the stress-induced adaptive and pathological consequences during the formation of post-stress states, in particular post-traumatic stress disorder (PTSD). Brief overview of epigenetic modifications was presented, while the process of DNA methylation was discussed comprehensively. Key stress-induced epigenetic changes in the human and animal brain in response to stress were summarized. Epigenetic modifications in certain genes (genes of stress responses, hormones and neurotransmitters genes, NGF gene) while post-stress states and PTSD formation were discussed in detail.
Assuntos
Montagem e Desmontagem da Cromatina , Metilação de DNA , Transtornos de Estresse Pós-Traumáticos/genética , Animais , Humanos , Transtornos de Estresse Pós-Traumáticos/metabolismoRESUMO
The effects of long-term mental and pain stress on H3Ser10 histone phosphorylation in neurons of the the sensorimotor corex and midbrain reticular formation were studied 24 h, 2 weeks, and 2 months after exposure of rats differing by the nervous system excitability. Rats with high excitability threshold exhibited higher basal level of H3Ser10 histone phosphorylation in the midbrain reticular formation neurons than rats with low excitability threshold. The sensorimotor cortical neurons of the two strains did not differ by this parameter. Stress led to a significant increase in the counts of immunopositive neuronal nuclei in rats with low excitability threshold: the parameter increased significantly in the sensorimotor cortex 24 h after exposure and normalized in 2 weeks after neurotization. In the midbrain reticular formation of this rat strain stress stimulated H3Ser10 histone phosphorylation after 24 h and after 2 weeks; the parameter normalized after neurotization in 2 months. Hence, genetically determined level of the nervous system excitability was essential for the basal level of neuron phosphorylation and for the time course of this process after long-term exposure to mental and pain stress, depending on the brain structure. A probable relationship between H3Ser10 histone phosphorylation process and liability to obsessive compulsive mental disorders in humans was discussed.
Assuntos
Núcleo Celular/metabolismo , Histonas/metabolismo , Formação Reticular Mesencefálica/metabolismo , Neurônios/metabolismo , Dor/metabolismo , Córtex Sensório-Motor/metabolismo , Estresse Psicológico/metabolismo , Animais , Imuno-Histoquímica , Fosforilação , Ratos , Limiar Sensorial , Fatores de TempoRESUMO
Process of methylation of histone H3 for lysine 4 (H3K4) was studied in hippocampal pyramidal neurons of rats--intact and submitted to emotional-painful stress with active and inactivated channels of NMDA-receptors with taking into account the interhemisphere lateralization and in connection with the genetically determined level of excitability of the animals' nervous system. There were revealed interstrain differences in the basal level of the H3K4 methylation whose direction depends on structural-functional peculiarities of hippocampal fields and lateralization. Under action of stress the direction of the observed changes in the degree of the H3K4 methylation depended on the functional state of channels of NMDA-receptors. On the background of active receptors the proportion of immunopositive cells predominantly increased. In the CA1 field those changes were not connected to excitability and lateralization, whereas in the CA3 field it had a complex character and depended on those two factors. At inactivation of channels of NMDA-receptors the portion of immunopositive nuclei as a result of the stress action, on the contrary, predominantly decreased; interstrain specificity of these changes was connected to lateralization, while its direction in different hippocampal fields was different. Action of the short-time emotional-painful stress did not lead to a change of shape of interhemisphere asymmetry at active state of receptors, whereas at inactivation of receptors it changes depending on the structural-functional organization of hippocampus and on excitability of the nervous system.
Assuntos
Potenciais de Ação , Região CA1 Hipocampal/metabolismo , Histonas/metabolismo , Processamento de Proteína Pós-Traducional , Células Piramidais/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Estresse Psicológico/metabolismo , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia , Lateralidade Funcional , Metilação , Células Piramidais/fisiologia , Ratos , Ratos Wistar , Limiar SensorialRESUMO
Long-term effects of chronic emotional and pain stress on histone H3 phosphorylation by serine 10 in hippocampal CA3 neurons were examined 24 h, 2 weeks, and 2 months after termination of the stress procedure in 2 rat strains differing by excitability of the nervous system. The low excitable rats with high threshold (HT) of excitability were characterized by a high baseline level of histone H3 phosphorylation in comparison with the high excitable rats with low threshold (LT) of excitability. The long-term emotional and pain stress significantly changed the number of positive immune cells in highly excitable rats: this parameter increased in 24 h and 2 weeks after the stress, but returned to the control level in 2 months. In contrast, stress did not affect histone H3 phosphorylation in low excitable rats. Thus, long-term (up to 2 weeks) changes in histone H3 phosphorylation were reveled in rat hippocampal CA3 neurons, which depended on genetically determined functional status of the nervous system.
Assuntos
Hipocampo/metabolismo , Histonas/metabolismo , Sistema Nervoso/metabolismo , Dor/fisiopatologia , Estresse Psicológico/fisiopatologia , Animais , Masculino , Fosforilação , RatosRESUMO
We studied the effects of prenatal emotional painful stress on numerical density of neurons and characteristics of heterochromatin in developing and mature hippocampus of rats with different excitability of the nervous systems. It was shown that prenatal stress reduces the numerical density of neurons in hippocampal CA3 field in 24-day-old and adult (3 months) low excitable animals and chromocenter area in cells of developing hippocampus in embryos of both strains. The difference in chromocenter areas in offspring of stressed females was retained on postnatal day 24.
Assuntos
Região CA3 Hipocampal/citologia , Heterocromatina/química , Neurônios/citologia , Fatores Etários , Animais , Região CA3 Hipocampal/fisiologia , Contagem de Células , Embrião de Mamíferos , Feminino , Masculino , Neurônios/fisiologia , Dor/psicologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Ratos , Tempo de Reação , Especificidade da Espécie , Estresse Psicológico/fisiopatologia , TempoRESUMO
Priority data on specific effect of long-term mental and pain stress on the dynamics of H4 histone acetylation in the pyramidal neuron nuclei of the hippocampal CA3 field in rats selected by the nervous system excitability were obtained using a comparative genetic method. The congruency of long-term post-stress modification of H4 histone acetylation in neurons of rats with high threshold excitability and behavioral changes intrinsic of these rats suggest that increased acetylation of H4 histone together with changes in heterochromatin conformation play a triggering role in long-term modifications of genome expression underlying the pathogenesis of posttraumatic stress disorders and other psychogenias.
Assuntos
Hipocampo/citologia , Histonas/metabolismo , Neurônios/metabolismo , Dor/metabolismo , Estresse Psicológico/metabolismo , Acetilação , Animais , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
In rats with low excitability threshold of the nervous system demonstrating significant and persistent behavioral disorders under stress conditions, the content of methylcytosine-binding protein MeCP2 in neuronal nuclei of hippocampal field CA3 decreased over 2 weeks after long-term emotional and pain stress. It was hypothesized that protein MeCP2 triggers epigenetic changes in DNA that underlie "stress memory".
Assuntos
Núcleo Celular/metabolismo , Hipocampo/citologia , Proteína 2 de Ligação a Metil-CpG/metabolismo , Neurônios/metabolismo , Dor/metabolismo , Transtornos de Estresse Pós-Traumáticos/metabolismo , Estresse Psicológico/metabolismo , Animais , Masculino , Ratos , Ratos WistarRESUMO
New data were obtained on modification of heterochromatin parameters in the nuclei of medulla oblongata neurons in Wistar rats after stimulation of the vagus nerve: decrease in the area of heterochromatin regions and redistribution of chromocenters within the neuronal nuclear system. It was concluded that realization of the viscero-visceral reflex is associated with rearrangement of chromatin in neurons involved in transmission of the corresponding information.
Assuntos
Heterocromatina/ultraestrutura , Bulbo/fisiologia , Nervo Vago/fisiologia , Animais , Estimulação Elétrica , Masculino , Bulbo/ultraestrutura , Neurônios/ultraestrutura , Ratos , Ratos Wistar , Reflexo/fisiologia , Núcleo Solitário/fisiologia , Núcleo Solitário/ultraestruturaRESUMO
The structural (number and area of chromocenters) and optical (relative optical density of chromocenters) characteristics of condensed chromatin in hippocampal CA3 neurons in rats differing by excitability of the nervous system (intact and exposed to short-term emotional painful stress) depended on the time of the day and genotypical characteristics of the experimental animals. The detected changes were independent, which attests to specificity of mechanisms determining these features and/or can be attributed to structural and functional heterogeneity of condensed chromatin (heterochromatin, euchromatin, etc.).
Assuntos
Cromatina/metabolismo , Hipocampo/citologia , Interfase , Neurônios/fisiologia , Estresse Psicológico , Animais , Ritmo Circadiano/genética , Masculino , Ratos , Ratos EndogâmicosRESUMO
This report describes the results of a comparative genetic analysis of the proliferation activity, level of chromosomal aberrations, and the state of interphase chromatin in nerve cells from the developing brains of rat embryos from lines with nervous systems of different excitation thresholds. A relationship between the basal level of nervous system excitability and these cytogenetic characteristics was found. Higher values were seen in embryos of the high-threshold line VP1, as compared with the low-threshold line NP1. The role of the cytogenetic characteristics of the embryo brain in the processes of CNS development and function are discussed in relation to the genetically determined level of nervous system excitability.