In vitro effect of antipsychotics on brain energy metabolism parameters in the brain of rats.

OBJECTIVE: Typical and atypical antipsychotic drugs have been shown to have different clinical, biochemical and behavioural profiles. It is well described that impairment of metabolism, especially in the mitochondria, leads to oxidative stress and neuronal death and has been implicated in the pathogenesis of a number of diseases in the brain. In this context, we investigated the in vitro effect of antipsychotic drugs on energy metabolism parameters in the brain of rats. METHODS: Clozapine (0.1, 0.5 and 1.0 mg/ml), olanzapine (0.1, 0.5 and 1.0 mg/ml) and aripiprazole (0.05, 0.15 and 0.3 mg/ml) were suspended in buffer and added to the reaction medium containing rat tissue homogenates and the respiratory chain complexes, succinate dehydrogenase and creatine kinase (CK) activities were evaluated. RESULTS: Our results showed that olanzapine and aripriprazole increased the activities of respiratory chain complexes. On the other hand, complex IV activity was inhibited by clozapine, olanzapine and aripriprazole. CK activity was increased by clozapine at 0.5 and 1.0 mg/ml in prefrontal cortex, cerebellum, striatum, hippocampus and posterior cortex of rats. Moreover, olanzapine and aripiprazole did not affect CK activity. CONCLUSION: In this context, if the hypothesis that metabolism impairment is involved in the pathophysiology of neuropsychiatric disorders is correct and these results also occur in vivo, we suggest that olanzapine may reverse a possible diminution of metabolism.

Activity of mitochondrial respiratory chain is increased by chronic administration of antidepressants.

OBJECTIVE: Depressive disorders, including major depression, are serious and disabling for affected patients. Although the neurobiological understanding of major depressive disorder focuses mainly on the monoamine hypothesis, the exact pathophysiology of depression is not fully understood. METHODS: Animals received daily intra-peritoneal injections of paroxetine (10 mg/kg), nortriptyline (15 mg/kg) or venlafaxine (10 mg/kg) in 1.0 ml/kg volume for 15 days. Twelve hours after the last injection, the rats were killed by decapitation, where the brain was removed and homogenised. The activities of mitochondrial respiratory chain complexes in different brain structures were measured. RESULTS: We first verified that chronic administration of paroxetine increased complex I activity in prefrontal cortex, hippocampus, striatum and cerebral cortex. In addition, complex II activity was increased by the same drug in hippocampus, striatum and cerebral cortex and complex IV activity in prefrontal cortex. Furthermore, chronic administration of nortriptyline increased complex II activity in hippocampus and striatum and complex IV activity in prefrontal cortex, striatum and cerebral cortex. Finally, chronic administration of venlafaxine increased complex II activity in hippocampus, striatum and cerebral cortex and complex IV activity in prefrontal cortex. CONCLUSION: On the basis of the present findings, it is tempting to speculate that an increase in brain energy metabolism by the antidepressant paroxetine, nortriptyline and venlafaxine could play a role in the mechanism of action of these drugs. These data corroborate with other studies suggesting that some antidepressants modulate brain energy metabolism.