Objective: Several studies support the hypothesis that metabolism impairment is involved in the pathophysiology of depression and that some antidepressants act by modulating brain energy metabolism. Thus, we evaluated the activity of Krebs cycle enzymes, the mitochondrial respiratory chain, and creatine kinase in the brain of rats subjected to prolonged administration of fluvoxamine. Methods: Wistar rats received daily administration of fluvoxamine in saline (10, 30, and 60 mg/kg) for 14 days. Twelve hours after the last administration, rats were killed by decapitation and the prefrontal cortex, cerebral cortex, hippocampus, striatum, and cerebellum were rapidly isolated. Results: The activities of citrate synthase, malate dehydrogenase, and complexes I, II-III, and IV were decreased after prolonged administration of fluvoxamine in rats. However, the activities of complex II, succinate dehydrogenase, and creatine kinase were increased. Conclusions: Alterations in activity of energy metabolism enzymes were observed in most brain areas analyzed. Thus, we suggest that the decrease in citrate synthase, malate dehydrogenase, and complexes I, II-III, and IV can be related to adverse effects of pharmacotherapy, but long-term molecular adaptations cannot be ruled out. In addition, we demonstrated that these changes varied according to brain structure or biochemical analysis and were not dose-dependent.
OBJECTIVE: Clinical findings suggest that ketamine may be used for the treatment of major depression. The present study aimed to compare behavioral effects and brain Creatine kinase activity in specific brain regions after administration of ketamine and imipramine in rats. METHOD: Rats were acutely given ketamine or imipramine and antidepressant-like activity was assessed by the forced swimming test; Creatine kinase activity was measured in different regions of the brain. RESULTS: The results showed that ketamine (10 and 15mg/kg) and imipramine (20 and 30mg/kg) reduced immobility time when compared to saline group. We also observed that ketamine (10 and 15mg/kg) and imipramine (20 and 30mg/kg) increased Creatine kinase activity in striatum and cerebral cortex. Ketamine at the highest dose (15mg/kg) and imipramine (20 and 30mg/kg) increased Creatine kinase activity in cerebellum and prefrontal cortex. On the other hand, hippocampus was not affected. CONCLUSION: Considering that metabolism impairment is probably involved in the pathophysiology of depressive disorders, the modulation of energy metabolism (like increase in Creatine kinase activity) by antidepressants could be an important mechanism of action of these drugs.
OBJETIVO: Vários achados clínicos sugerem que a cetamina apresenta efeito antidepressivo. O presente estudo tem como objetivo comparar efeitos comportamentais e a atividade da creatina quinase em regiões específicas do encéfalo após a administração de cetamina e imipramina em ratos. MÉTODO: Ratos Wistar receberam uma administração aguda de cetamina ou imipramina e a atividade antidepressiva foi avaliada pelo teste de nado forçado; a atividade da creatina quinase foi medida em diferentes regiões encefálicas. RESULTADOS: Os resultados mostraram que a cetamina (10 e 15mg/kg) e a imipramina (20 e 30mg/kg) diminuíram o tempo de imobilidade quando comparados ao grupo salina. Também foi observado que a cetamina (10 e 15mg/kg) e a imipramina (20 e 30mg/kg) aumentaram a atividade da creatina quinase no estriado e córtex cerebral. A dose mais alta de cetamina (15mg/kg) e a imipramina (20 e 30mg/kg) aumentaram a atividade da creatina quinase no cerebelo e córtex pré-frontal. Por outro lado, o hipocampo não foi alterado. CONCLUSÃO: Considerando que a diminuição no metabolismo provavelmente está envolvida na fisiopatologia da depressão, a modulação do metabolismo energético (como um aumento na atividade da creatina quinase) por antidepressivos pode ser um importante mecanismo de ação destes fármacos.