Avaliação de parâmetros neuroquímicos e comportamentais em fases iniciais e tardias em ratos sobreviventes à sepse

Tese de Doutorado apresentada ao Programa de Pós-Graduação em Ciências da Saúde da Universidade do Extremo Sul Catarinense – UNESC, para obtenção do título de Doutora em Ciências da Saúde.O objetivo deste estudo foi avaliar parâmetros neuroquímicos e comportamentais em fases iniciais e tardias em ratos submetidos ao modelo animal de sepse induzido por ligação e perfuração cecal. No experimento I, ratos Wistar machos (60 dias, 250-300g) foram divididos entre os grupos Sham (controle), Sepse 30 dias e Sepse 60 dias, com n=12. Após, foram retirados o córtex pré-frontal, hipocampo, estriado e córtex para análises dos níveis de substâncias reativas ao ácido tiobarbitúrico (TBARS); conteúdo de grupos carbonila; atividade dos complexos I, II, II-III e IV da cadeia respiratória mitocondrial e da enzima creatina quinase (CK). O fluido cerebrospinal foi coletado para quantificação das citocinas TNF-, IL-1 e IL-6, com n=5. No experimento II, os animais foram divididos entre os grupos Sham, Sepse e Sepse+Butirato de sódio (SB) (24 horas e 10 dias), com n=12. Por meio de cirurgia estereotáxica, SB ou fluido cerebroespinal artificial foram injetados no ventrículo lateral cerebral dos animais. Em 24 horas e 10 dias após, foram retirados o córtex pré-frontal, hipocampo, estriado e córtex, para análise da atividade de histonas desacetilases (HDAC). O teste de esquiva inibitória foi realizado 10 dias após a indução de sepse. No experimento III, os animais foram divididos entre os grupos sham e sepse 24 horas e 10 dias, com n=5. Após, o hipocampo foi retirado para quantificação dos níveis de fosforilação das proteínas ERK1/2, JNK1/2 e p38MAPK por Western blotting. Os resultados do Experimento I mostraram um aumento nos níveis de IL-6 no grupo sepse (30 dias); aumento nos níveis de TNF- no grupo sepse (60 dias); um aumento nos níveis de TBARS em córtex pré-frontal e uma diminuição destes níveis em hipocampo, estriado e córtex no grupo sepse (30 dias); uma diminuição do conteúdo de grupos carbonila em córtex pré-frontal e um aumento em estriado no grupo sepse (30 dias); uma diminuição nos níveis de TBARS em hipocampo no grupo sepse (60 dias); aumento do conteúdo de grupos carbonila em estriado no grupo sepse (60 dias). Também houve um aumento na atividade do complexo IV em hipocampo no grupo sepse (30 dias); uma diminuição na atividade do complexo I em córtex pré-frontal, hipocampo e estriado no grupo sepse (60 dias) e nenhuma diferença estatística na atividade da CK entre as estruturas cerebrais analisadas. Todos os dados foram analisados comparando o grupo sepse (30 e 60 dias) com o grupo sham. Já os resultados do Experimento II mostraram uma diminuição no tempo de latência nos animais do grupo sepse (10 dias) no teste de esquiva inibitória e a administração de SB reverteu o dano cognitivo observado nestes animais. Também foi observado um aumento na atividade de HDACs em hipocampo e córtex no grupo sepse (24 horas) e em córtex pré-frontal e hipocampo no grupo sepse (10 dias). Além disso, a administração de SB inibiu a atividade de HDACs em córtex pré-frontal e hipocampo dos animais do grupo sepse (10 dias). Todos os dados foram analisados comparando o grupo sepse (24 horas e 10 dias) com o grupo sham. Por fim, os resultados do Experimento III mostraram que não houve diferença significativa entre os grupos sham e sepse nos níveis de fosforilação das proteínas ERK1/2, JNK1/2 e p38MAPK em 24 horas e 10 dias após a sepse. Tomados em seu conjunto, os dados deste estudo podem contribuir para a compreensão do dano cognitivo observado em ratos sobreviventes à sepse, proporcionando novos conhecimentos que possam ter relevância clínica.The present study aimed to evaluate neurochemical and behavioral parameters in early and late phases in male Wistar rats (60 days old, 250-300g) subjected to an animal model of sepsis induced by cecal ligation and perforation. This work was divided in 3 steps: in the Experiment I, the animals were divided into groups Sham (control), Sepsis 30 days or Sepsis 60 days, with n=12. After, were dissected the prefrontal cortex, hippocampus, striatum and cortex in order to evaluate thiobarbituric acid reactive substances (TBARS) levels; carbonyl groups; activities of complexes I, II, II-III and IV of the mitochondrial respiratory chain and creatine kinase (CK). The cerebrospinal fluid was collected for quantification of TNF-, IL-1 and IL-6 cytokines, with n=5. In the Experiment II, the animals were divided into groups Sham, Sepsis and Sepsis+Sodium butyrate (SB), for (24 hours and 10 days), with n=12. SB or artificial cerebrospinal fluid were injected in the lateral ventricle in the brain of animals. After 24 hours or 10 days were dissected prefrontal cortex, hippocampus, striatum and cortex for histone deacetylase (HDAC) activity analysis. The inhibitory avoidance test was performed after 10 days of sepsis induction. In Experiment III, the animals were subjected to sham or sepsis 24 hours and 10 days, with n=5. After, the hippocampus was dissected for quantification of the phosphorylation levels of proteins ERK1/2, JNK1/2 and p38MAPK by Western blotting. The results of Experiment I showed increased levels of IL-6 in the sepsis group (30 days); increased levels of TNF- in the sepsis group (60 days); increased levels of TBARS in the prefrontal cortex and decreased in the hippocampus, striatum and cortex in the sepsis group (30 days); decreased carbonyl groups in the prefrontal cortex and the striatum and increased in the sepsis group (30 days); decreased levels of TBARS in the hippocampus in the sepsis group (60 days); increased carbonyl groups in the striatum in sepsis group (60 days); increased complex IV activity in the hippocampus in the sepsis group (30 days); decreased complex I activity in the prefrontal cortex, hippocampus and striatum in the sepsis group (60 days) and no statistical difference of CK activity in all analyzed brain structures. All data were analyzed by comparing the sepsis group (30 and 60 days) with the sham group. The results of Experiment II showed a decrease in latency in the animals of sepsis group (10 days) in the inhibitory avoidance test and the administration of SB reversed the cognitive damage observed in these animals. There was also an increase in HDACs activity in hippocampus and cortex in the sepsis group (24 hours) and prefrontal cortex and hippocampus in sepsis group (10 days). Moreover, the administration of SB inhibited HDAC activity in the prefrontal cortex and hippocampus of animals from sepsis group (10 days). All data were analyzed by comparing the sepsis group (24 hours and 10 days) with the sham group. The results of Experiment III showed no statistical difference between the sham and sepsis groups on the levels of phosphorylation of proteins ERK1/2, JNK1/2 and p38MAPK in 24 hours and 10 days after sepsis induction. Taken together, the results of the present study may contribute for comprehending the cognitive damage observed in sepsis survivor rats, providing new insights that might have clinical relevance

Effects of omega-3 supplementation on interleukin and neurotrophin levels in an animal model of schizophrenia

New studies suggest that polyunsaturated fatty acids, such as omega-3, may reduce the symptoms of schizophrenia. The present study evaluated the preventive effect of omega-3 on interleukines (IL) and neurotrophin brain-derived neurotrophic factor (BDNF) levels in the brains of young rats subjected to a model of schizophrenia. Treatment was performed over 21 days, starting on the 30th day of rat’s life. After 14 days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25 mg/kg) was started and maintained until the last day of the experiment. BDNF levels in the rat’s prefrontal cortex were decreased at 1 h and 24 h after the last administration of ketamine, whereas the group administered with ketamine and omega-3 showed a decrease in BDNF levels only after 24 h. In contrast, both interventions induced similar responses in levels of IL-1β and IL6. These findings suggest that the similarity of IL-1β and IL6 levels in our experimental groups is due to the mechanism of action of ketamine on the immune system. More studies have to be carried out to explain this pathology. In conclusion, according to previous studies and considering the current study, we could suggest a prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia

Effects of omega-3 supplementation on interleukin and neurotrophin levels in an animal model of schizophrenia

New studies suggest that polyunsaturated fatty acids, such as omega-3, may reduce the symptoms of schizophrenia. The present study evaluated the preventive effect of omega-3 on interleukines (IL) and neurotrophin brain-derived neurotrophic factor (BDNF) levels in the brains of young rats subjected to a model of schizophrenia. Treatment was performed over 21 days, starting on the 30th day of rat’s life. After 14 days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25 mg/kg) was started and maintained until the last day of the experiment. BDNF levels in the rat’s prefrontal cortex were decreased at 1 h and 24 h after the last administration of ketamine, whereas the group administered with ketamine and omega-3 showed a decrease in BDNF levels only after 24 h. In contrast, both interventions induced similar responses in levels of IL-1β and IL6. These findings suggest that the similarity of IL-1β and IL6 levels in our experimental groups is due to the mechanism of action of ketamine on the immune system. More studies have to be carried out to explain this pathology. In conclusion, according to previous studies and considering the current study, we could suggest a prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia

Resumos concluídos - Neurociências

Resumos concluídos -  Neurociência