Comparative Proteomics Analysis Of Rat With Antipsychotic Medications

Schizophrenia (MIM 181500), the most severe of psychiatric disorders, affects 1% of the world population with broadly equal prevalence throughout diverse cultures and geographic areas. Although a great deal of work has been done in this area, the molecular mechanism triggering schizophrenia has, so far, remained elusive. The etiology of schizophrenia appears to be multifaceted, with genetic, nutritional, environmental, and developmental factors all implicated. Because of the etiology and pathogenesis of schizophrenia are not clear, therefore clinical treatment of schizophrenia is mainly directed against symptoms rather than causes, there is not cure the disease itself, which makes the basis of schizophrenia research as a priority. In recent years, the rise of genomics, transcriptomics, proteomics and metabolomics for the study of schizophrenia has played a great role in promoting.Antipsychotic drugs remain the current standard of care for mental disorders including schizophrenia. Chlorpromazine (CPZ) was the first of the first-generation of antipsychotic drugs (the so-called"typical antipsychotics"). It operates on central dopaminergic pathways, and, although effective it has serious side effects. A number of new antipsychotic drugs (the so-called"atypical antipsychotics") have been introduced since 1990. Clozapine (CLZ) is the first atypical antipsychotic drug, so designated because it has more antipsychotic effects without the adverse mobility effects of the first-generation drugs. Subsequent antipsychotic drugs have followed, such as Quetiapine (QTP), Risperidone and Olanzapine, etc. The atypical antipsychotic drugs usually act on both dopamine (DA) receptors and 5-hydroxytryptamine (5-HT) receptors.An increasing number of experiments have found anomalies in mitochondria and synaptosome of the psychotics'brains, which suggests that mitochondrial dysfunction and abnormities in synaptosome might play some important roles in the pathophysiology of schizophrenia. Proteomics is a powerful tool for identifying protein expression alterations in disease tissue and has been successfully employed to study a variety of disorders, including schizophrenia. In this study, we used comparative proteomics to analyze expression changes of all mitochondrial proteins from the cerebral cortex and hippocampus, and synaptosomal proteins from the cerebral cortex of Sprague-Dawley (SD) rats, in response to antipsychotic medications. The rats were divided into four groups three of which were treated 34-day with CPZ, CLZ and QTP, respectively, and one control group.Differential mitochondrial protein expressions were assessed using two-dimensional electrophoresis-mass spectrometry (2DE-MS) for three groups with CPZ, CLZ, QTP and a control group. A total of 26 protein spots (14 proteins) showed significant changes in quantity. The differential proteins subjected to 2DE were assessed for levels of mRNA using quantitative real time PCR (Q-RT-PCR); and, we also made partial use of western blotting for assessing differential expression. Further pathways analyses of the 14 differentially expressed proteins were carried out using the DAVID online Gene Functional Classification Tool. The pathway analysis indicated that 6 proteins, Ndufa10, Ndufv2, Ndufs3, Atp5b, Atp6v1b2, and Atp6v1a1 were ETC members participating in OXPHOS. Complex I is the rate-limiting step of the ETC, and if the efficiency of ETC is affected, then OXPHOS efficiency will be affected. Antipsychotic drugs not only inhibited the Complex I, also by inhibiting the subunits of ATP synthase (Complex V) Atp5b, Atp6v1b2 and Atp6v1a1, to achieve inhibition ATP synthesis. Defects in mitochondrial function and inability to maintain cellular ATP levels have been suggested as a possible cause for the slow neurodegeneration and aberrations associated with neuronal diseases.Similarity, a comparative proteomics approach was applied using 2DE-MS to identify the effects of antipsychotic drugs, CPZ, CLZ and QTP on the synaptosomal protein of SD rats'cerebral cortex. 17 protein spots were showed univariate statistically significant change in quantity and 12 of them were successfully identified using MS. In our study, we failed to verify the positive results of proteomics analysis using Q-RT-PCR. Similarly, we also failed to verify Ppp1cc differentially expressed in three treatment groups on the total protein of cerebral cortex using western blotting. And then, the multivariate statistical test, partial least squares-discriminant analysis (PLS-DA) was performed to build the PLS-DA model for screening out variable important plot (VIP). The final models can successfully distinguish each drug treatment group and the control; more importantly, the differentially expressed proteins obtained using univariate statistical tests were ideally verified by VIP of PLS-DA models. In order to further study the relationship among the significant proteins by univariate and multivariate statistical test. Pearson's correlation analysis was performed using 2DE data between each treatment group and the control. We obtained a meaningful result. The results of Pearson's correlation analysis were similar between each antipsychotic drug treatment group and the control. Antipsychotic drugs interrupted the existing concurrencies among the proteins (CPZ vs. control), or created some new concurrencies among them (QTP vs. control), or existed both two phenomena (CLZ vs. control). Pearson's correlation analysis revealed that these proteins are possible antipsychotic drugs or disease-related proteins. The interrelationships among the identified proteins were analyzed using pathway analysis. Eventually, we found the mitochondrial function of the energy production,'Glycolysis/Gluconeogenesis'and G protein-coupled signal trans-membrane transduction in synaptosome of cerebral cortex, were involved in response to antipsychotic medications. Synaptosome contains lots of mitochondria, enabling production of ATP supporting the activities of cell communications, signal transduction, etc. Any factor adversely affecting the ability of mitochondria to carry out ATP production is likely to have detrimental consequences for brain development and function. These energy metabolism pathways have been changed in the process of antipsychotic medication, might be owing to the effects of antipsychotic drugs themselves or organisms' response to antipsychotic medications. G protein-coupled receptors (GPCRs) can be activated by the outside signals to activate inside signal transduction pathways. GPCRs play an important role in G protein-dependent signaling pathways and their dysfunction would lead to the emergence of many disorders.In addition, we found many differentially expressed proteins of mitochondria and synaptosome in our experiment which have been shown to associate with schizophrenia or antipsychotic drugs. The results of our study may help to explain variations in SD rats as well as in human response to antipsychotic drugs. In addition, our results may help to improve our understanding of the impact of antipsychotic drugs on mitochondrial and synaptosomal functions, and to provide further understanding of the curative effects and the side effects of the antipsychotic drugs.