Fluvoxamine alters the activity of energy metabolism enzymes in the brain

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. .

Fluvoxamine alters the activity of energy metabolism enzymes in the brain.

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.

Effects of tamoxifen on tricarboxylic acid cycle enzymes in the brain of rats submitted to an animal model of mania induced by amphetamine.

The neurobiological basis of bipolar disorder (BD) remains unknown; nevertheless, mitochondrial dysfunction has been identified in this disorder. Inactivation of any step in the tricarboxylic acid (TCA) cycle can impair mitochondrial ATP production. There is recent evidence indicating that PKC is an important therapeutic target for bipolar disorder. Therefore, we evaluated the effects of tamoxifen (TMX--a PKC inhibitor) on the activities of enzymes in the TCA cycle of rat brains subjected to an animal model of mania induced by amphetamine. In the reversal treatment, Wistar rats were first treated with d-AMPH or saliratsne (Sal) for 14 days. Thereafter, between days 8 and 14, the rats were administered TMX or Sal. The citrate synthase, succinate dehydrogenase, and malate dehydrogenase were evaluated in the frontal cortex, hippocampus, and striatum. The d-AMPH administration inhibited TCA cycle enzymes activity in all analyzed structures, and TMX reversed d-AMPH-induced dysfunction. In addition, we observed a negative correlation between d-AMPH-induced hyperactivity and the activity of these enzymes in the rat's brain. These findings suggested that TCA cycle enzymes inhibition can be an important link for the mitochondrial dysfunction seen in BD, and TMX exert protective effects against the d-AMPH-induced TCA cycle enzymes dysfunction.

Sodium butyrate reverses the inhibition of Krebs cycle enzymes induced by amphetamine in the rat brain.

There is increasing interest in the possibility that mitochondrial impairment may play an important role in bipolar disorder (BD). The Krebs cycle is the central point of oxidative metabolism, providing carbon for biosynthesis and reducing agents for generation of ATP. Recently, studies have suggested that histone deacetylase (HDAC) inhibitors may have antimanic effects. The present study aims to investigate the effects of sodium butyrate (SB), a HDAC inhibitor, on Krebs cycle enzymes activity in the brain of rats subjected to an animal model of mania induced by D-amphetamine (D-AMPH). Wistar rats were first given D-AMPH or saline (Sal) for 14 days, and then, between days 8 and 14, rats were treated with SB or Sal. The citrate synthase (CS), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH) were evaluated in the prefrontal cortex, hippocampus, and striatum of rats. The D-AMPH administration inhibited Krebs cycle enzymes activity in all analyzed brain structures and SB reversed D-AMPH-induced dysfunction analyzed in all brain regions. These findings suggest that Krebs cycle enzymes' inhibition can be an important link for the mitochondrial dysfunction seen in BD and SB exerts protective effects against the D-AMPH-induced Krebs cycle enzymes' dysfunction.

Methylphenidate treatment leads to abnormalities on krebs cycle enzymes in the brain of young and adult rats.

Studies have shown a relationship between energy metabolism and methylphenidate (MPH); however, there are no studies evaluating the effects of MPH in Krebs cycle. So, we investigated if MPH treatment could alter the activity of citrate synthase (CS), malate dehydrogenase (MD), and isocitrate dehydrogenase (ID) in the brain of young and adult Wistar rats. Our results showed that MPH (2 and 10 mg/kg) reduced CS in the striatum and prefrontal cortex (PF), with MPH at all doses in the cerebellum and hippocampus after chronic treatment in young rats. In adult rats the CS was reduced in the cerebellum after acute treatment with MPH at all doses, and after chronic treatment in the PF and cerebellum with MPH (10 mg/kg), and in the hippocampus with MPH (2 and 10 mg/kg). The ID decreased in the hippocampus and striatum with MPH (2 and 10 mg/kg), and in the cortex (10 mg/kg) after acute treatment in young rats. In adult rats acute treatment with MPH (2 and 10 mg/kg) reduced ID in the cerebellum, and with MPH (10 mg/kg) in the cortex; chronic treatment with MPH (10 mg/kg) decreased ID in the PF; with MPH (2 and 10 mg/kg) in the cerebellum, and with MPH at all doses in the hippocampus. The MD did not alter. In conclusion, our results suggest that MPH can alter enzymes of Krebs cycle in brain areas involved with circuits related with attention deficit hyperactivity disorder; however, such effects depend on age of animal and treatment regime.