Increased mRNA levels of the mitochondrial complex I 75-kDa subunit

Recently, the dopamine D₃-receptor mRNA on blood lymphocytes and platelet mitochondrial complex I were suggested as biological markers of schizophrenia in adults. We investigated the mRNA level of the dopamine D₃-receptor and complex I subunits in whole blood cells of early-onset schizophrenic patients compared to healthy controls using quantitative real-time PCR. We found an increased mRNA expression of the complex I 75-kDa subunit (referred to beta-actin in schizophrenic patients (0.57 ± 0.24 versus 0.23 ± 0.18 in controls, P < 0.01)), but were unable to analyse the dopamine D₃-mRNA expression. This increase appears to be inherent to schizophrenia, because it was found in neuroleptic-naive patients and it was not affected by neuroleptic treatment. Our preliminary findings suggest the mitochondrial complex I as a potential peripheral marker of schizophrenia and its involvement in the pathophysiology of this illness.