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Original Article |

Mitochondrial Complex I Activity and Oxidative Damage to Mitochondrial Proteins in the Prefrontal Cortex of Patients With Bipolar Disorder FREE

Ana C. Andreazza, PharmD, PhD; Li Shao, PhD; Jun-Feng Wang, PhD; L. Trevor Young, MD, PhD
[+] Author Affiliations

Author Affiliations: Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada.


Arch Gen Psychiatry. 2010;67(4):360-368. doi:10.1001/archgenpsychiatry.2010.22.
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Context  Accumulating evidence suggests that mitochondrial dysfunction and oxidative stress contribute to the pathogenesis of bipolar disorder and schizophrenia. It remains unclear whether mitochondrial dysfunction, specifically complex I impairment, is associated with increased oxidative damage and, if so, whether this relationship is specific to bipolar disorder.

Objective  To evaluate whether decreased levels of the electron transport chain complex I subunit NDUFS7 are associated with complex I activity and increased oxidative damage to mitochondrial proteins in the prefrontal cortex of patients with bipolar disorder, schizophrenia, or major depressive disorder.

Design  Postmortem prefrontal cortex from patients and controls were assessed using immunoblotting, spectrophotometric, competitive enzyme immunoassay to identify group differences in expression and activity of complex I, and in oxidative damage in mitochondria.

Setting  University of British Columbia, Vancouver, Canada.

Patients  Forty-five patients with a psychiatric disorder (15 each with bipolar disorder, schizophrenia, and major depressive disorder) and 15 nonpsychiatric control subjects were studied.

Main Outcome Measures  Oxidative damage to proteins and mitochondrial complex I activity.

Results  Levels of NDUFS7 and complex I activity were decreased significantly in patients with bipolar disorder but were unchanged in those with depression and schizophrenia compared with controls. Protein oxidation, as measured by protein carbonylation, was increased significantly in the bipolar group but not in the depressed or schizophrenic groups compared with controls. We observed increased levels of 3-nitrotyrosine in the bipolar disorder and schizophrenia groups.

Conclusions  Impairment of complex I may be associated with increased protein oxidation and nitration in the prefrontal cortex of patients with bipolar disorder. Therefore, complex I activity and mitochondrial dysfunction may be potential therapeutic targets for bipolar disorder.

Figures in this Article

Bipolar disorder (BD) is a chronic psychiatric illness characterized by recurrent episodes of mania, hypomania, mixed states, and depression. It has been increasingly recognized that individuals with BD are at higher risk for chronic general medical conditions, such as obesity, diabetes mellitus, and cardiovascular disease,1,2 which are directly associated with the increased morbidity and mortality observed in BD. Despite decades of extensive investigation, the etiology and pathogenesis of this disorder remain unclear. Several postmortem studies36 have reported reduced neuronal and glial density in discrete regions of the prefrontal cortex of patients with BD. In addition, Davis et al7 found reductions in cortical gray matter and cerebral white matter volumes in male patients with familial BD type I. Mitochondrial dysfunction,8,9 and the consequent oxidative damage to lipids, proteins, and DNA,9 might be one of the possible mechanisms contributing to neuronal or glial impairment in BD.

Mitochondria are intracellular organelles that have a crucial role in adenosine triphosphate (ATP) production through oxidative phosphorylation, a process performed by the electron transport chain (ETC) complexes I through V.10 Mitochondria also serve as calcium buffers, regulators of apoptosis, and generators of reactive oxygen species (ROS).10,11 Mitochondrial ATP production occurs through the flow of electrons that are passed along ETC complexes in the inner mitochondrial membrane. Energy lost by protons reentering the mitochondrial matrix through ATP synthase is used to produce ATP.12 During transfer along the ETC, single electrons sometimes escape and result in a single-electron reduction of molecular oxygen to form a superoxide anion (O2), especially in complex I (also known as nicotinamide adenine dinucleotide [NADH]–ubiquinone oxidoreductase).13 Mitochondrial O2 reacts with superoxide dismutase, which converts the O2 into hydrogen peroxide (H2O2), which can, in the presence of ferrous iron (Fe3+) via the Fenton reaction (H2O2 + Fe2+ → Fe3+ + OH + OH), result in the production of highly reactive hydroxyl radicals (OH). Another relevant event is the reaction of O2 with nitric oxide (NO) to form peroxynitrite (ONOO). When mitochondrial and cytoplasm enzymatic and nonenzymatic antioxidant systems are overwhelmed by elevated levels of ROS and reactive nitrogen species, oxidative damage can occur to DNA, lipids (cell and organelle membranes), and proteins (receptors, transcription factors, and enzymes).14 Oxidative damage to proteins may be caused by reactions of amino acid residues with (1) ROS, especially OH, catalyzed by Fe2+ and cupric (Cu2+), which introduce carbonyl groups in lysine, proline, arginine, and threonine residues15,16; or (2) ONOO, which nitrates sulfhydryl and hydroxyl residues in cysteine, methionine, phenylalanine, and tyrosine; these modifications could inactivate the membrane signaling pathways and key enzymes.17,18 3-Nitrotyrosine is produced by the nitration of tyrosine residues in protein and serves as a marker for in vivo oxidative damage induced by ONOO.18 Oxidative modifications can also affect the function of specific proteins, such as enzymatic activity, DNA binding activities of transcription factors,15 and susceptibility to proteolytic degradation.16

Several lines of evidence suggest that mitochondrial dysfunction has a role in the pathogenesis of BD because these individuals have been noted, for example, to have altered cerebral energy metabolism19,20 and an increased ratio of mitochondrial DNA deletion.21 Recent DNA microarray analyses in postmortem prefrontal cortex22,23 and hippocampus24 revealed that the expression of many messenger RNAs (mRNAs) coding for ETC complexes I to V subunits was decreased in patients with BD. In addition, evidence from at least some genotyping studies25,26 suggest that polymorphisms of the complex I subunit NDUFV2 may be associated with BD. Several studies2730 have also suggested altered activity and expression of mitochondrial ETC components in postmortem brain samples from patients with schizophrenia. Furthermore, mitochondrial ATP production measured in a muscle biopsy specimen was reported to be decreased in patients with major depressive disorder (MDD).31 Complex I is one of the main sites in which electrons are released and react with oxygen, resulting in ROS production, thus causing oxidative stress. Indeed, recent studies have demonstrated alterations in a diverse set of oxidative stress parameters in patients with BD. For example, studies conducted with peripheral blood cells have demonstrated that BD is associated with alterations in antioxidant enzymes,3234 increased lipid peroxidation,33,34 increased levels of nitric oxide,3537 and increased DNA fragmentation.38,39 Moreover, we40 reported increased levels of lipid peroxidation in the cingulate cortex of patients with BD.

Sun et al,22 using high-density complementary DNA spot microarrays, reported downregulation of 8 mitochondrial ETC-related genes: NDUFS7 and NDUFS8 (complex I), UQCRC2 (complex III), COX5A and COX6C (complex IV), and ATP5C1, ATP5J, and ATP5G3 (complex V). Using real-time quantitative polymerase chain reaction, we further verified that mRNA levels of NDUFS7 were decreased. Because NDUFS7 levels were decreased and may contribute to decreased complex I activity,41 in the present study we examined NDUFS7 protein levels and complex I activity as an indication of mitochondrial complex I impairment. Complex I is a major source of ROS production, which can cause oxidative damage to proteins. We, therefore, also analyzed protein oxidation (carbonyl content) and tyrosine nitration (3-nitrotyrosine levels) as markers of oxidative damage to mitochondrial proteins to improve understanding of the pathogenesis of BD.

POSTMORTEM BRAIN SAMPLES

Prefrontal cortex tissue samples were from Brodmann area 10 (1.0-g blocks). Participants were divided into 4 groups: BD, MDD, schizophrenia, and nonpsychiatric control subjects (n = 15 per group) matched for age, sex, and postmortem interval (PMI) (Table). Diagnoses were retrospectively established by 2 senior psychiatrists using DSM-IV criteria. Detailed clinical information, diagnostic procedures, and demographic information on these individuals have been previously published.42 The investigators were blinded to the group identity, diagnosis, and demographic variables of the participants during all experiments and measurements. Samples were randomly coded numerically, and the code was lifted only during data analyses, after all of the experiments were completed.

Table Graphic Jump LocationTable. Demographic and Clinical Data for Postmortem Brain Tissue in Patients and Controls
MITOCHONDRIAL EXTRACTION

Mitochondria-enriched extracts were prepared as described by Smith,43 with minor modifications. Briefly, prefrontal cortex tissues were homogenized in buffer 1 (0.25M sucrose, 2mM EDTA, and 10mM Tris hydrochloride; pH 7.2) at a ratio of 20 μL/mg of tissue. Homogenized samples were centrifuged (at 5600g for 3 minutes). The supernatant was kept on ice, and the pellet was resuspended in buffer 1, homogenized, and recentrifuged (at 5600g for 3 minutes). The combined supernatants were centrifuged (at 37 500g for 20 minutes). Mitochondria-enriched pellets were dissolved in buffer 2 (2M aminocaproic acid, 150mM Bis-Tris hydrochloride, and 500mM EDTA; pH 7.0) at a ratio of 4 μL/mg of tissue. These homogenates were centrifuged (at 12 000g for 15 minutes). The supernatants were collected and used for complex I enzymatic assay and immunoblotting analysis. Protein concentrations in the supernatants were determined using the Bradford assay. To verify that this method is reliable with frozen samples, we compared the protein concentrations and the complex I activity in fresh and frozen rat brain. The cerebral cortex was removed (n = 4) and submersed in ice-cold calcium (Ca2+)- and magnesium (Mg2+)-free Hanks balanced saline solution. Mean (SD) protein concentrations in fresh (2.15 [0.30] μg/μL) and frozen (1.91 [0.21] μg/μL) mitochondrial fractions were not significantly different (t = 1.99; P = .13). No significant difference was found in mean (SD) complex I activity comparing fresh (2.37 [0.22] μmol/min) and frozen (2.15 [0.21] μmol/min) rat brain samples (t = 1.82; P = .16).

NDUFS7 LEVELS

Protein levels of NDUFS7 were measured by means of immunoblotting. Thirty micrograms of mitochondrial extract was loaded on 12% acrylamide sodium dodecyl sulfate–polyacrylamide gel electrophoresis gel and were subsequently transferred onto polyvinylidene difluoride membranes. Membranes were blocked with 0.05% polysorbate 20 in 0.01M phosphate-buffered solution containing 5% nonfat milk (PBS-T) for 2 hours at room temperature. The blots were independently probed using either mouse anti–human NDUFS7 antibody (Novus Biologicals, Littleton, Colorado), 1:1000, or antiporin antibody (Abcam Inc, Cambridge, Massachusetts), 1:3000, as mitochondria-loading control in PBS-T at 4°C overnight with gentle shaking. Membranes were washed with PBS-T 4 times (10 minutes each time) and then were incubated with rabbit anti–mouse horseradish peroxidase conjunct secondary antibody (Abcam Inc), 1:3000, in PBS-T for 2 hours at room temperature. Finally, membranes were washed with PBS-T 4 times (10 minutes each time) before applying electrochemiluminescence reagents (GE Co, Piscataway, New Jersey). Protein bands were analyzed densitometrically and were normalized to the porin signal using a molecular imaging system (VersaDoc; Bio-Rad Laboratories, Hercules, California).

COMPLEX I ACTIVITY

Complex I activity was performed as described by Estornell et al.44 Briefly, mitochondria-enriched pellets were diluted to 10 to 15 μg/mL in the assay buffer (50mM potassium chloride, 10mM Tris hydrochloride, 1mM EDTA, and 2mM potassium cyanide; pH 7.4). The NADH, 75μM, was added. The reaction was started by the addition of 50μM coenzyme Q1 and was read at 340 nm against the blank containing all the components except the coenzyme Q1 for 5 minutes. The rate after inhibition was determined with the same reagents plus the inhibitor rotenone for 5 minutes. Complex I activity was calculated by subtracting the rate after the addition of rotenone (10μM) from the overall rate.

PROTEIN OXIDATION

Protein oxidation was assessed by measuring the levels of carbonyl groups using the OxyBlot Protein Oxidation Detection Kit (catalog No. S7150; Chemicon, Kankakee, Illinois). The carbonyl groups in the protein side chains are derivatized from 2,4-dinitrophenylhydrazone by reaction with 2,4-dinitrophenylhydrazine. The 2,4-dinitrophenylhydrazone–derivatized protein samples were separated by means of polyacrylamide gel electrophoresis and Western blotting following the OxyBlot kit instructions. Protein bands were analyzed densitometrically and were normalized against the intensity of porin using VersaDoc.

TYROSINE NITRATION–INDUCED DAMAGE

Tyrosine nitration–induced damage was assessed by measuring 3-nitrotyrosine levels using the OxiSelect Nitrotyrosine ELISA [enzyme-linked immunosorbent assay] Kit (catalog No. STA-305; Cell Biolabs Inc, San Diego, California). The unknown protein nitrotyrosine sample or nitrated bovine serum albumin standards were first added to a nitrated bovine serum albumin–preabsorbed enzyme immunoassay plate. After a brief incubation, the anti–nitrotyrosine antibody was added, followed by the horseradish peroxidase–conjugated secondary antibody. The protein nitrotyrosine content in the unknown samples was determined by comparison with a standard curve prepared using predetermined nitrated bovine serum albumin standards.

STATISTICAL METHODS

Statistical analyses were performed using a computer software program (SPSS for Windows version 16.0; SPSS Inc, Chicago, Illinois) software. Normal distribution of data was determined using the Kolmogorov-Smirnov test. For further analysis, parametric tests were used because most of the data (90%) had a normal distribution. Data were analyzed by means of 2-way analysis of variance, followed by the least significant difference post hoc test. Age, sex, PMI, and brain pH were added as covariates, and persistence of the significant difference in main effect between diagnostic groups was assessed by means of analysis of covariance. Correlations were analyzed using the Pearson correlation test. Data are given as mean (SD).

DEMOGRAPHIC VARIABLES

Demographic and clinical characteristics of patients and controls are given in the Table. Controls (n = 15) were matched with patients with BD (n = 15), MDD (n = 15), and schizophrenia (n = 15) for age and sex; therefore, as expected, no significant differences were noted among groups on these measures. The PMI (F = 1.857, P = .15) and pH (F = 0.611, P = .61) were not significantly different among groups. The PMI was not correlated with NDUFS7 expression (r2 = 0.021, P = .10), complex I activity (r2 = 0.016, P = .11), carbonyl levels (r2 = 0.001, P = .22), or 3-nitrotyrosine levels (r2 = 0.005, P = .33). The pH did not correlate with complex I activity (r2 = 0.023, P = .72), carbonyl levels (r2 = 0.008, P = .29), or 3-nitrotyrosine levels (r2 = 0.022, P = .11) but correlated positively with NDUFS7 levels (r2 = 0.105, P = .01) (Figure 1). To assess whether patients who committed suicide had more mitochondrial dysfunction or protein damage, we divided the patients into 2 subgroups: death by suicide (n = 20) and death by other causes (n = 25). No significant difference between these groups was observed in complex I activity, NDUFS7 expression, protein carbonylation, or 3-nitrotyrosine levels.

Place holder to copy figure label and caption
Figure 1.

Relation between complex I activity (A), NDUFS7 expression (B), protein oxidation (C), and tyrosine nitration–induced damage (D) and pH. Results were assessed using the Pearson correlation test. AU indicates arbitrary units.

Graphic Jump Location
MITOCHONDRIAL COMPLEX I DYSFUNCTION AND PROTEIN DAMAGE

We found that NDUFS7 levels were significantly different comparing the 4 groups. The group difference in NDUFS7 levels (F3,56 = 5.691, P = .002) was due to a significant decrease in NDUFS7 levels in the BD group (62.38%, P = .003) compared with controls (Figure 2A). Expression of NDUFS7 was not different in patients with MDD (P = .16) or in those with schizophrenia (P = .41) compared with controls. To control for potential confounding variables, age, sex, PMI, and brain pH were added as covariates and were assessed by means of analysis of covariance. The differences between the groups remained significant even after these variables were added to the analysis (F3 = 4.798, P = .01). Adding pH to the analysis had a significant effect (F3 = 6.271, P = .02) but did not alter the significant decrease in NDUFS7 levels.

Place holder to copy figure label and caption
Figure 2.

Levels of NDUFS7 (A) and complex I activity (B) in postmortem prefrontal cortex of control (CTL), bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SCZ) subjects. Complex I, also known as nicotinamide adenine dinucleotide [NADH]–ubiquinone oxidoreductase, is a multisubunit integral membrane complex of the mitochondrial electron transport chain that catalyzes electron transfer from NADH to ubiquinone. The activity of complex I was measured by following the oxidation of NADH at 340 nm. The immunocontent of NDUFS7 was analyzed by means of Western blotting. Differences among groups were analyzed using 1-way analysis of variance, followed by the least significant difference test comparing the patient groups with the control group. Horizontal lines indicate means; error bars, SE. AU indicates arbitrary units. *P < .001; †P < .005.

Graphic Jump Location

Complex I activity was markedly decreased (53.12%) in patients with BD (F3,56 = 12.85, P < .001) and was decreased to a lesser extent in those with MDD (17.98%, P = .003) in relation to controls. There were no significant differences in complex I activity in patients with schizophrenia compared with controls (P = .47) (Figure 2B). Controlling for potential confounding variables (age, sex, PMI, and brain pH) by means of analysis of covariance did not alter the main effect (F3 = 13.56, P < .001).

To assess oxidative and nitrosative damage to mitochondrial proteins, we analyzed protein carbonylation and 3-nitrotyrosine levels in the postmortem samples. There were significant differences between groups in carbonylation levels (F3,56 = 3.01, P = .04) (Figure 3A) and nitration levels (F3,56 = 4.56, P = .007) (Figure 3B). Patients with BD had increased carbonyl content (P = .01) and 3-nitrotyrosine levels (P = .001) compared with controls. 3-Nitrotyrosine levels were also significantly increased in patients with schizophrenia compared with the control group (P = .03). Patients with MDD did not differ from the control and other patient groups on either of these protein oxidation markers. Analysis of covariance did not demonstrate any effect from the potential confounding factors.

Place holder to copy figure label and caption
Figure 3.

Mitochondrial protein carbonyl immunocontent (A) and 3-nitrotyrosine levels (B) in postmortem prefrontal cortex of control (CTL), bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SCZ) subjects. Mitochondrial protein carbonyl levels were analyzed by means of Western blotting. 3-Nitrotyrosine levels were analyzed by means of competitive enzyme-linked immunosorbent assay. Horizontal lines represent means; error bars, SE (n = 14 CTL; n = 15 BD; n = 15 MDD; and n = 14 SCZ). Differences among groups were analyzed using 1-way analysis of variance, followed by the least significant difference test comparing the patient groups with the control group. AU indicates arbitrary units. *P < .01; †P < .05.

Graphic Jump Location

Next, we analyzed the relationship between complex I activity and NDUFS7 levels, protein oxidation, and tyrosine nitration. As expected, complex I activity was positively correlated with NDUFS7 levels (n = 60; r2 = 0.185, P = .001). The present results show that complex I activity was correlated negatively with carbonyl levels (n = 57; r2 = 0.299, P = .02) and 3-nitrotyrosine levels (n = 57; r2 = 0.113, P = .01) (Figure 4).

Place holder to copy figure label and caption
Figure 4.

Correlations among complex I activity and NDUFS7 levels (A), protein oxidation (carbonyl levels) (B), and tyrosine nitration–induced damage (3-nitrotyrosine) (C). Results were assessed using the Pearson correlation test. AU indicates arbitrary units.

Graphic Jump Location
EFFECT OF MEDICATION

Antipsychotic drugs have been reported to be potential inhibitors of complex I activity.27 To assess the potential effect of antipsychotics on the present results, we divided the patients into 2 subgroups: patients with schizophrenia or BD treated with antipsychotics (conventional and second-generation drugs) at the time of death (n = 20 [12 with schizophrenia and 8 with BD]) (Table) and those who were not (n = 10 [3 with schizophrenia and 7 with BD]). Because none of the patients in the other 2 groups were treated with this class of drugs at the time of death, they were excluded from the analysis. No significant difference was observed between the 2 subgroups in complex I activity, NDUFS7 levels, protein carbonyl content, or 3-nitrotyrosine levels. There was a nonsignificant trend for decreased mean (SD) complex I activity in patients treated with antipsychotics (0.81 [0.34] μmol/min) compared with those who had not been treated with antipsychotics (1.08 [0.30] μmol/min) (t = −0.456, P = .08). Next, to assess the possible effects of antidepressant medications on the results, we divided the patients into 2 subgroups: those treated with antidepressant drugs (n = 23 [10 with MDD, 5 with schizophrenia , and 8 with BD]) and those not treated with antidepressant drugs (n = 22 [5 with MDD, 10 with schizophrenia, and 7 with BD]). No significant differences were observed between the groups for any of these measures. Finally, recent studies,45 including ours, have suggested that lithium carbonate has potential antioxidant capacity. We divided the patients into groups treated with lithium (n = 14 [2 with MDD, 2 with schizophrenia, and 10 with BD]) and those who had not received lithium (n = 31 [13 with MDD, 13 with schizophrenia, and 5 with BD]). No significant differences were observed between these 2 subgroups in complex I activity, NDUFS7 expression, protein carbonyl content, or 3-nitrotyrosine levels.

We report that NDUFS7 levels and complex I activity are decreased and levels of mitochondrial protein oxidation and tyrosine nitration are increased in postmortem prefrontal cortex of patients with BD compared with age- and sex-matched nonpsychiatric controls. There were no differences in NDUFS7 levels in patients with either MDD or schizophrenia, but a small decrease in complex I activity was found in the MDD group compared with controls. Increased 3-nitrotyrosine levels were also found in patients with schizophrenia compared with the control group. We found a negative correlation between complex I activity and protein carbonylation or 3-nitrotyrosine levels. These results, together with evidence from other neurologic diseases,41 provide evidence that decreased NDUFS7 levels contribute to complex I impairment, in this case, in BD. Decreased complex I activity is widely reported to increase superoxide production,10,11,13,14 and this free radical, in turn, induces oxidative15 and nitrosative46 damage to proteins. Nevertheless, multiple factors regulate complex I activity, including alterations in other complex I subunits, increased neurotoxin levels, glutathione depletion, decreased ATP production, and increased ONOO levels.14,41 The present study identifies NDUFS7 as a factor that potentially contributes to complex I impairment. There is growing evidence that mitochondrial impairment, particularly in mitochondrial complex I, contributes to the pathogenesis of BD.2224,45

Microarray data have suggested that decreased expression of many mRNAs coding for complexes I through V subunits are associated with BD.2224 More specifically, Iwamoto et al47 demonstrated decreased mRNA levels of the complex I subunit NDUFS1, complex III subunit UQCRC2, and complex IV subunit COX15 in the prefrontal cortex of patients with BD. Sun et al22 showed that 8 genes coding for subunits of ETC complexes I, III, IV, and V were downregulated in postmortem prefrontal cortex of patients with BD: NDUFS7 and NDUFS8 (complex I), UQCRC2 (complex III), COX5A and COX6C (complex IV), and ATP5C1, ATP5J, and ATP5G3 (complex V). To confirm these data, Sun et al22 evaluated mRNA levels of NDUFS7, UQCRC2, COX6C, and ATP5G3 using real-time quantitative polymerase chain reaction and found decreased mRNA levels of NDUFS7 and COX6C. Mitochondrial dysfunction has also been reported in schizophrenia. Using transcriptomic, proteomic, and metabolomic analysis, Prabakaran et al30 showed that half of the altered protein expression in patients with schizophrenia was related to mitochondrial dysfunction and oxidative stress and that these were mirrored by transcriptional and metabolite perturbations. NDUFS1 was shown to be decreased in white and gray matter of the prefrontal cortex from patients with schizophrenia.28 In addition, decreased activity of complex IV was found in the caudate nucleus48 and frontal and temporal cortices,29 and succinate dehydrogenase (complex II) activity was increased in the putamen and nucleus accumbens of patients with schizophrenia.49 Complex I activity was also found to be reduced in the temporal cortex but not in the frontal cortex27 or caudate nucleus in patients with schizophrenia.49 More recently, Karry et al27 observed reduced expression of 2 catalytic subunits of mitochondrial complex I, 24 kDa (NDUFV2) and 51 kDa (NDUFV1), in the prefrontal cortex of patients with schizophrenia compared with controls. The present results did not find differences in NDUFS7 levels and complex I activity in the schizophrenia group. The differences in the results may be explained, in part, by the fact that Karry et al27 evaluated the RNA expression levels of subunits different than those analyzed herein and used brain tissue from Brodmann area 46/9, whereas the present samples were from Brodmann area 10.

The findings highlighted herein illustrate that downregulation of several complex I subunits occurs in BD, which may be associated with the susceptibility of BD to damage through oxidative stress. Human complex I is composed of 45 to 46 different subunits and is divided into 3 functional modules. First, the dehydrogenase module is responsible for the oxidation of NADH via flavin mononucleotide onto a chain of iron-sulfur clusters. Second, the hydrogenase module guides the released electrons to electron acceptors. Third, the transporter module is responsible for translocation of protons across the membrane.50 In BD, decreased expression of NDUFV225,26 and NDUFS147 in the dehydrogenase module and decreased expression of NDUFS722 and NDUFS822 in the hydrogenase module have been reported. These results suggest that patients with BD may have a reduced ability to oxidize NADH and to transfer electrons to ubiquinone. In that respect, electrons may persist for sufficient time to react with molecular oxygen and, thus, produce O2.51,52 In addition, Benes et al53 found that superoxide dismutase, catalase, several isoforms of glutathione peroxidase and glutathione S-transferase, and other genes associated with antioxidant reactions were downregulated in the hippocampus of patients with BD but not schizophrenia. Together, the organization of complex I, the downregulation of complex I subunits, and the decreased levels of the antioxidant system strongly support the susceptibility of mitochondrial proteins to oxidative damage in BD.1218

In this study, patients with BD demonstrated increased levels of carbonylated proteins, which were shown to be negatively correlated with complex I activity. One possible mechanism through which impaired complex I activity could be associated with increased protein carbonylation in BD is the overproduction of OH, by reaction of O2 with superoxide dismutase.15,16 OH reacts with lysine, proline, arginine, and threonine residues of proteins by creating carbonyl groups.15 Carbonylation can alter protein function or can lead to deleterious intermolecular aggregates that preclude their degradation by the proteasomal system.15,16 Konradi et al24 demonstrated decreased expression of genes involved in the proteasome degradation process in prefrontal cortex from patients with BD, suggesting that in addition to potential mechanisms leading to increased protein carbonylation, the normal process of degradation may also be impaired, leading to further accumulation. Indeed, accumulation of carbonylated proteins has been implicated in the etiology or progression of several chronic central nervous system disorders, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and multiple sclerosis.54,55 Therefore, future studies using redox proteomic techniques will be critical to identify whether specific mitochondrial proteins are targets of protein oxidation and, if so, to define the relationship between oxidative protein modification (ie, carbonylation) and cellular function in BD.

These results also demonstrate increased levels of 3-nitrotyrosine in the prefrontal cortex of patients with BD and those with schizophrenia compared with nonpsychiatric controls. 3-Nitrotyrosine is a posttranslational modification in protein tyrosine residue nitrated by ONOO (peroxynitrite).18,46 In the brain, NO is produced by microglia and astrocytes and is subsequently transported to neurons, where it may react with superoxide to yield ONOO.18 Neuronal nitric oxide synthase 1, the enzyme that generates NO, was found to be upregulated in the hippocampus of patients with BD,56 in addition to increased serum levels of NO in patients with the same disorder.3537 Our group57 previously reported increased serum levels of 3-nitrotyrosine in patients with BD early (0-3 years) and late (10-20 years) in the course of the illness. In addition, Murray et al46 showed that ONOO reactions with mitochondrial membranes from bovine heart occur predominantly in complex I subunits, resulting in significant inhibition of complex I activity, suggesting a functional relation between complex I activity and nitration. This is further supported by the report of Naoi et al18 of increased 3-nitrotyrosine levels in the mitochondrial complex I subunits but not in other mitochondrial proteins of SH-SY5Y cells incubated with ONOO. These findings, along with those of the present study, may suggest that mitochondrial complex I proteins are susceptible to the nitration process and that this modification contributes importantly to the mitochondrial dysfunction observed in BD.

These results must be interpreted in light of the limitations of the samples and methods. First, some of these reported changes could be related to lower brain pH, which is commonly associated with antemortem agonal states, postmortem delay, and storage of tissue.58 We suggest that such changes in pH may, indeed, be related to the diagnosis and treatment of BD, as suggested by Kato et al59 and Hamakawa et al.60 We did not find differences in pH or PMI between groups (Table). However, pH correlated positively with NDUFS7 levels but not with complex I activity, 3-nitrotyrosine levels, and carbonyl levels. The covariates pH, PMI, age, and sex did not contribute significantly to the main findings, as demonstrated by the subsequent data analysis. Second, drug treatment is another important consideration; however, we did not find significant effects of treatment with lithium, antidepressants, or antipsychotics on any of these measures. Third, considering that we studied postmortem brain, the results also might be limited by a small sample and analysis of a single region, the prefrontal cortex. Results of a recent study40 also indicate oxidative stress in the anterior cingulate cortex of patients with BD. The authors acknowledge the efforts of many groups to collect postmortem brain samples from larger groups of patients with better control over these important variables as a future strategy to control for these limitations. Therefore, additional brain regions require further investigation to understand the specificity of oxidative stress in psychiatric diseases.

In conclusion, these results provide evidence of the involvement of mitochondrial complex I dysfunction and consequent oxidative damage to proteins in BD but not in schizophrenia. Accumulation of oxidative damage to mitochondrial proteins is thought to lead to neuronal cell death by apoptosis or as a consequence of aggregation of oxidized protein that may result in neurodegeneration.61 Complex I deficiency may sensitize neurons to mitochondria-dependent apoptosis in response to the proapoptotic protein Bax, which releases the soluble pool of cytochrome c in the mitochondrial intermembrane space, activating the programmed cell death by caspase 3 and 9.61,62 In addition, Benes et al53 showed that several apoptotic genes, including FAS, BAK, APAF-1, NFkB65, TRAF1, BID, c-Myc, c-jun, and MDM2, are upregulated in the hippocampus of individuals with BD but not in patients with schizophrenia, suggesting an important role of the apoptotic process in BD. Future studies are needed to identify which specific mitochondrial proteins are targets of carbonylation and nitration in patients with BD and possibly to identify new targets of neuroprotective strategies and to help elucidate a better understanding of the pathogenesis of BD.

Correspondence: L. Trevor Young, MD, PhD, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC V6T 2A1, Canada (trevor.young@ubc.ca).

Submitted for Publication: June 3, 2009; final revision received August 6, 2009; accepted August 20, 2009.

Financial Disclosure: Dr Andreazza has been supported by CNPq (Brazil) and CAPES (Brazil). Dr Wang has received research grants from the Canadian Institutes of Health Research and the National Alliance for Research on Schizophrenia and Depression. Dr Young has received research grants from the Canadian Institutes of Health Research and from the Stanley Foundation and is an occasional speaker for Eli Lilly and AstraZeneca.

Funding/Support: This study is supported by grants from the Canadian Institutes of Health Research (Drs Wang and Young), by the Stanley Medical Research Institute (Dr Young), and by a Young Investigator award from the National Alliance for Research on Schizophrenia and Depression (Dr Wang). Specimens were donated by the Stanley Medical Research Institute Brain Collection courtesy of Michael B. Knable, DO; E. Fuller Torrey, MD; Maree J. Webster, PhD; and Robert H. Yolken, MD.

Previous Presentations: This study was presented in part at the 64th Annual Convention of the Society of Biological Psychiatry; May 14, 2009; Vancouver, British Columbia, Canada, and at the 63rd Annual Convention of the Society of Biological Psychiatry; May 1, 2008; Washington, DC.

Additional Contributions: Lakshmi Yatham, MD, and Jonathan Hebb, MD, provided important revisions to the manuscript.

Kupfer  DJ The increasing medical burden in bipolar disorder. JAMA 2005;293 (20) 2528- 2530
PubMed Link to Article
Kapczinski  FDias  VVKauer-Sant’Anna  MFrey  BNGrassi-Oliveira  RColom  FBerk  M Clinical implications of a staging model for bipolar disorders. Expert Rev Neurother 2009;9 (7) 957- 966
PubMed Link to Article
Ongür  DDrevets  WCPrice  JL Glial reduction in the subgenual prefrontal cortex in mood disorders. Proc Natl Acad Sci U S A 1998;95 (22) 13290- 13295
PubMed Link to Article
Rajkowska  GHalaris  ASelemon  LD Reductions in neuronal and glial density characterize the dorsolateral prefrontal cortex in bipolar disorder. Biol Psychiatry 2001;49 (9) 741- 752
PubMed Link to Article
Uranova  NOrlovskaya  DVikhreva  OZimina  IKolomeets  NVostrikov  VRachmanova  V Electron microscopy of oligodendroglia in severe mental illness. Brain Res Bull 2001;55 (5) 597- 610
PubMed Link to Article
Vostrikov  VMUranova  NAOrlovskaya  DD Deficit of perineuronal oligodendrocytes in the prefrontal cortex in schizophrenia and mood disorders. Schizophr Res 2007;94 (1-3) 273- 280
PubMed Link to Article
Davis  KAKwon  ACardenas  VADeicken  RF Decreased cortical gray and cerebral white matter in male patients with familial bipolar I disorder. J Affect Disord 2004;82 (3) 475- 485
PubMed
Papa  LRockwell  P Persistent mitochondrial dysfunction and oxidative stress hinder neuronal cell recovery from reversible proteasome inhibition. Apoptosis 2008;13 (4) 588- 599
PubMed Link to Article
Takuma  KBaba  AMatsuda  T Astrocyte apoptosis: implications for neuroprotection. Prog Neurobiol 2004;72 (2) 111- 127
PubMed Link to Article
Jeong  SYSeol  DW The role of mitochondria in apoptosis. BMB Rep 2008;41 (1) 11- 22
PubMed Link to Article
Kuwana  TNewmeyer  DD Bcl-2-family proteins and the role of mitochondria in apoptosis. Curr Opin Cell Biol 2003;15 (6) 691- 699
PubMed Link to Article
Reeve  AKKrishnan  KJTurnbull  DM Age related mitochondrial degenerative disorders in humans. Biotechnol J 2008;3 (6) 750- 756
PubMed Link to Article
Green  DRKroemer  G The pathophysiology of mitochondrial cell death. Science 2004;305 (5684) 626- 629
PubMed Link to Article
Lenaz  G The mitochondrial production of reactive oxygen species: mechanisms and implications in human pathology. IUBMB Life 2001;52 (3-5) 159- 164
PubMed Link to Article
Beal  MF Oxidatively modified proteins in aging and disease. Free Radic Biol Med 2002;32 (9) 797- 803
PubMed Link to Article
Rivett  AJ Regulation of intracellular protein turnover: covalent modification as a mechanism of marking proteins for degradation. Curr Top Cell Regul 1986;28291- 337
PubMed
Berlett  BSLevine  RLStadtman  ER Carbon dioxide stimulates peroxynitrite-mediated nitration of tyrosine residues and inhibits oxidation of methionine residues of glutamine synthetase: both modifications mimic effects of adenylylation. Proc Natl Acad Sci U S A 1998;95 (6) 2784- 2789
PubMed Link to Article
Naoi  MMaruyama  WShamoto-Nagai  MYi  HAkao  YTanaka  M Oxidative stress in mitochondria: decision to survival and death of neurons in neurodegenerative disorders. Mol Neurobiol 2005;31 (1-3) 81- 93
PubMed Link to Article
Kato  TTakahashi  SShioiri  TInubushi  T Alterations in brain phosphorous metabolism in bipolar disorder detected by in vivo 31P and 7Li magnetic resonance spectroscopy. J Affect Disord 1993;27 (1) 53- 59
PubMed Link to Article
Frey  BNStanley  JANery  FGMonkul  ESNicoletti  MAChen  HHHatch  JPCaetano  SCOrtiz  OKapczinski  FSoares  JC Abnormal cellular energy and phospholipid metabolism in the left dorsolateral prefrontal cortex of medication-free individuals with bipolar disorder: an in vivo 1H MRS study. Bipolar Disord 2007;9(suppl 1)119- 127
PubMed Link to Article
Kato  TStine  OC McMahon  FJCrowe  RR Increased levels of a mitochondrial DNA deletion in the brain of patients with bipolar disorder. Biol Psychiatry 1997;42 (10) 871- 875
PubMed Link to Article
Sun  XWang  JFTseng  MYoung  LT Downregulation in components of mitochondrial electron transport chain in postmortem frontal cortex from subjects with bipolar disorder. J Psychiatry Neurosci 2006;31 (3) 189- 196
PubMed
Iwamoto  KBundo  MKato  T Altered expression of mitochondria-related genes in postmortem brains of patients with bipolar disorder or schizophrenia, as revealed by large-scale DNA microarray analysis. Hum Mol Genet 2005;14 (2) 241- 253
PubMed Link to Article
Konradi  CEaton  MMacDonald  MLWalsh  JBenes  FMHeckers  S Molecular evidence for mitochondrial dysfunction in bipolar disorder. Arch Gen Psychiatry 2004;61 (3) 300- 308
PubMed Link to Article
Washizuka  SIwamoto  KKakiuchi  CBundo  MKato  T Expression of mitochondrial complex I subunit gene NDUFV2 in the lymphoblastoid cells derived from patients with bipolar disorder and schizophrenia. Neurosci Res 2009;63 (3) 199- 204
PubMed Link to Article
Xu  CLi  PPKennedy  JLGreen  MHughes  BCooke  RGParikh  SVWarsh  JJ Further support for association of the mitochondrial complex I subunit gene NDUFV2 with bipolar disorder. Bipolar Disord 2008;10 (1) 105- 110
PubMed Link to Article
Karry  RKlein  EBen Shachar  D Mitochondrial complex I subunits expression is altered in schizophrenia: a postmortem study. Biol Psychiatry 2004;55 (7) 676- 684
PubMed Link to Article
Ben-Shachar  DZuk  RGazawi  HReshef  ASheinkman  AKlein  E Increased mitochondrial complex I activity in platelets of schizophrenic patients. Int J Neuropsychopharmacol 1999;2 (4) 245- 253
PubMed Link to Article
Maurer  IZierz  SMoller  H Evidence for a mitochondrial oxidative phosphorylation defect in brains from patients with schizophrenia. Schizophr Res 2001;48 (1) 125- 136
PubMed Link to Article
Prabakaran  SSwatton  JERyan  MMHuffaker  SJHuang  JTGriffin  JLWayland  MFreeman  TDudbridge  FLilley  KSKarp  NAHester  STkachev  DMimmack  MLYolken  RHWebster  MJTorrey  EFBahn  S Mitochondrial dysfunction in schizophrenia: evidence for compromised brain metabolism and oxidative stress. Mol Psychiatry 2004;9 (7) 684- 697, 643
PubMed Link to Article
Gardner  AJohansson  AWibom  RNennesmo  Ivon Döbeln  UHagenfeldt  LHällström  T Alterations of mitochondrial function and correlations with personality traits in selected major depressive disorder patients. J Affect Disord 2003;76 (1-3) 55- 68
PubMed Link to Article
Kuloglu  MUstundag  BAtmaca  MCanatan  HTezcan  AECinkilinc  N Lipid peroxidation and antioxidant enzyme levels in patients with schizophrenia and bipolar disorder. Cell Biochem Funct 2002;20 (2) 171- 175
PubMed Link to Article
Andreazza  ACCassini  CRosa  ARLeite  MCde Almeida  LMNardin  PCunha  ABCeresér  KMSantin  AGottfried  CSalvador  MKapczinski  FGonçalves  CA Serum S100B and antioxidant enzymes in bipolar patients. J Psychiatr Res 2007;41 (6) 523- 529
PubMed Link to Article
Machado-Vieira  RAndreazza  ACViale  CIZanatto  VCereser  V  Jrda Silva Vargas  RKapczinski  FPortela  LVSouza  DOSalvador  MGentil  V Oxidative stress parameters in unmedicated and treated bipolar subjects during initial manic episode: a possible role for lithium antioxidant effects. Neurosci Lett 2007;421 (1) 33- 36
PubMed Link to Article
Savaş  HAHerken  HYürekli  MUz  ETutkun  HZoroğlu  SSOzen  MECengiz  BAkyol  O Possible role of nitric oxide and adrenomedullin in bipolar affective disorder. Neuropsychobiology 2002;45 (2) 57- 61
PubMed Link to Article
Savas  HAGergerlioglu  HSArmutcu  FHerken  HYilmaz  HRKocoglu  ESelek  STutkun  HZoroglu  SSAkyol  O Elevated serum nitric oxide and superoxide dismutase in euthymic bipolar patients: impact of past episodes. World J Biol Psychiatry 2006;7 (1) 51- 55
PubMed Link to Article
Selek  SSavas  HAGergerlioglu  HSBulbul  FUz  EYumru  M The course of nitric oxide and superoxide dismutase during treatment of bipolar depressive episode. J Affect Disord 2008;107 (1-3) 89- 94
PubMed Link to Article
Andreazza  ACFrey  BNErdtmann  BSalvador  MRombaldi  FSantin  AGonçalves  CAKapczinski  F DNA damage in bipolar disorder. Psychiatry Res 2007;153 (1) 27- 32
PubMed Link to Article
Buttner  NBhattacharyya  SWalsh  JBenes  FM DNA fragmentation is increased in non-GABAergic neurons in bipolar disorder but not in schizophrenia. Schizophr Res 2007;93 (1-3) 33- 41
PubMed Link to Article
Wang  JFShao  LSun  XYoung  LT Increased oxidative stress in anterior cingulate cortex of subjects with bipolar disorder and schizophrenia. Bipolar Disord 2009;11 (5) 523- 529
PubMed Link to Article
Lebon  SMinai  LChretien  DCorcos  JSerre  VKadhom  NSteffann  JPauchard  JYMunnich  ABonnefont  JPRötig  A A novel mutation of the NDUFS7 gene leads to activation of a cryptic exon and impaired assembly of mitochondrial complex I in a patient with Leigh syndrome. Mol Genet Metab 2007;92 (1-2) 104- 108
PubMed Link to Article
Torrey  EFWebster  MKnable  MJohnston  NYolken  RH The Stanley Foundation brain collection and neuropathology consortium. Schizophr Res 2000;44 (2) 151- 155
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Smith  AL Preparation, properties, and conditions for assay of mitochondria: slaughterhouse material, small-scale. Methods Enzymol 1967;1081- 86
Estornell  EFato  RPallotti  FLenaz  G Assay conditions for the mitochondrial NADH: coenzyme Q oxidoreductase. FEBS Lett 1993;332 (1-2) 127- 131
PubMed Link to Article
Wang  JF Defects of mitochondrial electron transport chain in bipolar disorder: implications for mood-stabilizing treatment. Can J Psychiatry 2007;52 (12) 753- 762
PubMed
Murray  JTaylor  SWZhang  BGhosh  SSCapaldi  RA Oxidative damage to mitochondrial complex I due to peroxynitrite: identification of reactive tyrosines by mass spectrometry. J Biol Chem 2003;278 (39) 37223- 37230
PubMed Link to Article
Iwamoto  KKakiuchi  CBundo  MIkeda  KKato  T Molecular characterization of bipolar disorder by comparing gene expression profiles of postmortem brains of major mental disorders. Mol Psychiatry 2004;9 (4) 406- 416
PubMed Link to Article
Cavelier  LJazin  EEEriksson  IPrince  JBåve  UOreland  LGyllensten  U Decreased cytochrome-c oxidase activity and lack of age-related accumulation of mitochondrial DNA deletions in the brains of schizophrenics. Genomics 1995;29 (1) 217- 224
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Prince  JABlennow  KGottfries  CGKarlsson  IOreland  L Mitochondrial function is differentially altered in the basal ganglia of chronic schizophrenics. Neuropsychopharmacology 1999;21 (3) 372- 379
PubMed Link to Article
Brandt  UKerscher  SDröse  SZwicker  KZickermann  V Proton pumping by NADH:ubiquinone oxidoreductase: a redox driven conformational change mechanism? FEBS Lett 2003;545 (1) 9- 17
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Benes  FMMatzilevich  DBurke  REWalsh  J The expression of proapoptosis genes is increased in bipolar disorder, but not in schizophrenia. Mol Psychiatry 2006;11 (3) 241- 251
PubMed Link to Article
Castegna  AAksenov  MAksenova  MThongboonkerd  VKlein  JBPierce  WMBooze  RMarkesbery  WRButterfield  DA Proteomic identification of oxidatively modified proteins in Alzheimer's disease brain, part I: creatine kinase BB, glutamine synthase, and ubiquitin carboxy-terminal hydrolase L-1. Free Radic Biol Med 2002;33 (4) 562- 571
PubMed Link to Article
Castegna  AAksenov  MThongboonkerd  VKlein  JBPierce  WMBooze  RMarkesbery  WRButterfield  DA Proteomic identification of oxidatively modified proteins in Alzheimer's disease brain, part II: dihydropyrimidinase-related protein 2, α-enolase and heat shock cognate 71. J Neurochem 2002;82 (6) 1524- 1532
PubMed Link to Article
Oliveira  RMGuimarães  FSDeakin  JF Expression of neuronal nitric oxide synthase in the hippocampal formation in affective disorders. Braz J Med Biol Res 2008;41 (4) 333- 341
PubMed Link to Article
Andreazza  ACKapczinski  FKauer-Sant’Anna  MWalz  JCBond  DJGonçalves  CAYoung  LTYatham  LN 3-Nitrotyrosine and glutathione antioxidant system in patients in the early and late stages of bipolar disorder. J Psychiatry Neurosci 2009;34 (4) 263- 271
PubMed
Vawter  MPTomita  HMeng  FBolstad  BLi  JEvans  SChoudary  PAtz  MShao  LNeal  CWalsh  DMBurmeister  MSpeed  TMyers  RJones  EGWatson  SJAkil  HBunney  WE Mitochondrial-related gene expression changes are sensitive to agonal-pH state: implications for brain disorders. Mol Psychiatry 2006;11 (7) 615, 663- 679
PubMed
Kato  TMurashita  JKamiya  AShioiri  TKato  NInubushi  T Decreased brain intracellular pH measured by 31P-MRS in bipolar disorder: a confirmation in drug-free patients and correlation with white matter hyperintensity. Eur Arch Psychiatry Clin Neurosci 1998;248 (6) 301- 306
PubMed Link to Article
Hamakawa  HMurashita  JYamada  NInubushi  TKato  NKato  T Reduced intracellular pH in the basal ganglia and whole brain measured by 31P-MRS in bipolar disorder. Psychiatry Clin Neurosci 2004;58 (1) 82- 88
PubMed Link to Article
Pierri  JNVolk  CLAuh  SSampson  ALewis  DA Decreased somal size of deep layer 3 pyramidal neurons in the prefrontal cortex of subjects with schizophrenia. Arch Gen Psychiatry 2001;58 (5) 466- 473
PubMed Link to Article
Ricci  CPastukh  VLeonard  JTurrens  JWilson  GSchaffer  DSchaffer  SW Mitochondrial DNA damage triggers mitochondrial-superoxide generation and apoptosis. Am J Physiol Cell Physiol 2008;294 (2) C413- C422
PubMed Link to Article

Figures

Place holder to copy figure label and caption
Figure 1.

Relation between complex I activity (A), NDUFS7 expression (B), protein oxidation (C), and tyrosine nitration–induced damage (D) and pH. Results were assessed using the Pearson correlation test. AU indicates arbitrary units.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.

Levels of NDUFS7 (A) and complex I activity (B) in postmortem prefrontal cortex of control (CTL), bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SCZ) subjects. Complex I, also known as nicotinamide adenine dinucleotide [NADH]–ubiquinone oxidoreductase, is a multisubunit integral membrane complex of the mitochondrial electron transport chain that catalyzes electron transfer from NADH to ubiquinone. The activity of complex I was measured by following the oxidation of NADH at 340 nm. The immunocontent of NDUFS7 was analyzed by means of Western blotting. Differences among groups were analyzed using 1-way analysis of variance, followed by the least significant difference test comparing the patient groups with the control group. Horizontal lines indicate means; error bars, SE. AU indicates arbitrary units. *P < .001; †P < .005.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 3.

Mitochondrial protein carbonyl immunocontent (A) and 3-nitrotyrosine levels (B) in postmortem prefrontal cortex of control (CTL), bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SCZ) subjects. Mitochondrial protein carbonyl levels were analyzed by means of Western blotting. 3-Nitrotyrosine levels were analyzed by means of competitive enzyme-linked immunosorbent assay. Horizontal lines represent means; error bars, SE (n = 14 CTL; n = 15 BD; n = 15 MDD; and n = 14 SCZ). Differences among groups were analyzed using 1-way analysis of variance, followed by the least significant difference test comparing the patient groups with the control group. AU indicates arbitrary units. *P < .01; †P < .05.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 4.

Correlations among complex I activity and NDUFS7 levels (A), protein oxidation (carbonyl levels) (B), and tyrosine nitration–induced damage (3-nitrotyrosine) (C). Results were assessed using the Pearson correlation test. AU indicates arbitrary units.

Graphic Jump Location

Tables

Table Graphic Jump LocationTable. Demographic and Clinical Data for Postmortem Brain Tissue in Patients and Controls

References

Kupfer  DJ The increasing medical burden in bipolar disorder. JAMA 2005;293 (20) 2528- 2530
PubMed Link to Article
Kapczinski  FDias  VVKauer-Sant’Anna  MFrey  BNGrassi-Oliveira  RColom  FBerk  M Clinical implications of a staging model for bipolar disorders. Expert Rev Neurother 2009;9 (7) 957- 966
PubMed Link to Article
Ongür  DDrevets  WCPrice  JL Glial reduction in the subgenual prefrontal cortex in mood disorders. Proc Natl Acad Sci U S A 1998;95 (22) 13290- 13295
PubMed Link to Article
Rajkowska  GHalaris  ASelemon  LD Reductions in neuronal and glial density characterize the dorsolateral prefrontal cortex in bipolar disorder. Biol Psychiatry 2001;49 (9) 741- 752
PubMed Link to Article
Uranova  NOrlovskaya  DVikhreva  OZimina  IKolomeets  NVostrikov  VRachmanova  V Electron microscopy of oligodendroglia in severe mental illness. Brain Res Bull 2001;55 (5) 597- 610
PubMed Link to Article
Vostrikov  VMUranova  NAOrlovskaya  DD Deficit of perineuronal oligodendrocytes in the prefrontal cortex in schizophrenia and mood disorders. Schizophr Res 2007;94 (1-3) 273- 280
PubMed Link to Article
Davis  KAKwon  ACardenas  VADeicken  RF Decreased cortical gray and cerebral white matter in male patients with familial bipolar I disorder. J Affect Disord 2004;82 (3) 475- 485
PubMed
Papa  LRockwell  P Persistent mitochondrial dysfunction and oxidative stress hinder neuronal cell recovery from reversible proteasome inhibition. Apoptosis 2008;13 (4) 588- 599
PubMed Link to Article
Takuma  KBaba  AMatsuda  T Astrocyte apoptosis: implications for neuroprotection. Prog Neurobiol 2004;72 (2) 111- 127
PubMed Link to Article
Jeong  SYSeol  DW The role of mitochondria in apoptosis. BMB Rep 2008;41 (1) 11- 22
PubMed Link to Article
Kuwana  TNewmeyer  DD Bcl-2-family proteins and the role of mitochondria in apoptosis. Curr Opin Cell Biol 2003;15 (6) 691- 699
PubMed Link to Article
Reeve  AKKrishnan  KJTurnbull  DM Age related mitochondrial degenerative disorders in humans. Biotechnol J 2008;3 (6) 750- 756
PubMed Link to Article
Green  DRKroemer  G The pathophysiology of mitochondrial cell death. Science 2004;305 (5684) 626- 629
PubMed Link to Article
Lenaz  G The mitochondrial production of reactive oxygen species: mechanisms and implications in human pathology. IUBMB Life 2001;52 (3-5) 159- 164
PubMed Link to Article
Beal  MF Oxidatively modified proteins in aging and disease. Free Radic Biol Med 2002;32 (9) 797- 803
PubMed Link to Article
Rivett  AJ Regulation of intracellular protein turnover: covalent modification as a mechanism of marking proteins for degradation. Curr Top Cell Regul 1986;28291- 337
PubMed
Berlett  BSLevine  RLStadtman  ER Carbon dioxide stimulates peroxynitrite-mediated nitration of tyrosine residues and inhibits oxidation of methionine residues of glutamine synthetase: both modifications mimic effects of adenylylation. Proc Natl Acad Sci U S A 1998;95 (6) 2784- 2789
PubMed Link to Article
Naoi  MMaruyama  WShamoto-Nagai  MYi  HAkao  YTanaka  M Oxidative stress in mitochondria: decision to survival and death of neurons in neurodegenerative disorders. Mol Neurobiol 2005;31 (1-3) 81- 93
PubMed Link to Article
Kato  TTakahashi  SShioiri  TInubushi  T Alterations in brain phosphorous metabolism in bipolar disorder detected by in vivo 31P and 7Li magnetic resonance spectroscopy. J Affect Disord 1993;27 (1) 53- 59
PubMed Link to Article
Frey  BNStanley  JANery  FGMonkul  ESNicoletti  MAChen  HHHatch  JPCaetano  SCOrtiz  OKapczinski  FSoares  JC Abnormal cellular energy and phospholipid metabolism in the left dorsolateral prefrontal cortex of medication-free individuals with bipolar disorder: an in vivo 1H MRS study. Bipolar Disord 2007;9(suppl 1)119- 127
PubMed Link to Article
Kato  TStine  OC McMahon  FJCrowe  RR Increased levels of a mitochondrial DNA deletion in the brain of patients with bipolar disorder. Biol Psychiatry 1997;42 (10) 871- 875
PubMed Link to Article
Sun  XWang  JFTseng  MYoung  LT Downregulation in components of mitochondrial electron transport chain in postmortem frontal cortex from subjects with bipolar disorder. J Psychiatry Neurosci 2006;31 (3) 189- 196
PubMed
Iwamoto  KBundo  MKato  T Altered expression of mitochondria-related genes in postmortem brains of patients with bipolar disorder or schizophrenia, as revealed by large-scale DNA microarray analysis. Hum Mol Genet 2005;14 (2) 241- 253
PubMed Link to Article
Konradi  CEaton  MMacDonald  MLWalsh  JBenes  FMHeckers  S Molecular evidence for mitochondrial dysfunction in bipolar disorder. Arch Gen Psychiatry 2004;61 (3) 300- 308
PubMed Link to Article
Washizuka  SIwamoto  KKakiuchi  CBundo  MKato  T Expression of mitochondrial complex I subunit gene NDUFV2 in the lymphoblastoid cells derived from patients with bipolar disorder and schizophrenia. Neurosci Res 2009;63 (3) 199- 204
PubMed Link to Article
Xu  CLi  PPKennedy  JLGreen  MHughes  BCooke  RGParikh  SVWarsh  JJ Further support for association of the mitochondrial complex I subunit gene NDUFV2 with bipolar disorder. Bipolar Disord 2008;10 (1) 105- 110
PubMed Link to Article
Karry  RKlein  EBen Shachar  D Mitochondrial complex I subunits expression is altered in schizophrenia: a postmortem study. Biol Psychiatry 2004;55 (7) 676- 684
PubMed Link to Article
Ben-Shachar  DZuk  RGazawi  HReshef  ASheinkman  AKlein  E Increased mitochondrial complex I activity in platelets of schizophrenic patients. Int J Neuropsychopharmacol 1999;2 (4) 245- 253
PubMed Link to Article
Maurer  IZierz  SMoller  H Evidence for a mitochondrial oxidative phosphorylation defect in brains from patients with schizophrenia. Schizophr Res 2001;48 (1) 125- 136
PubMed Link to Article
Prabakaran  SSwatton  JERyan  MMHuffaker  SJHuang  JTGriffin  JLWayland  MFreeman  TDudbridge  FLilley  KSKarp  NAHester  STkachev  DMimmack  MLYolken  RHWebster  MJTorrey  EFBahn  S Mitochondrial dysfunction in schizophrenia: evidence for compromised brain metabolism and oxidative stress. Mol Psychiatry 2004;9 (7) 684- 697, 643
PubMed Link to Article
Gardner  AJohansson  AWibom  RNennesmo  Ivon Döbeln  UHagenfeldt  LHällström  T Alterations of mitochondrial function and correlations with personality traits in selected major depressive disorder patients. J Affect Disord 2003;76 (1-3) 55- 68
PubMed Link to Article
Kuloglu  MUstundag  BAtmaca  MCanatan  HTezcan  AECinkilinc  N Lipid peroxidation and antioxidant enzyme levels in patients with schizophrenia and bipolar disorder. Cell Biochem Funct 2002;20 (2) 171- 175
PubMed Link to Article
Andreazza  ACCassini  CRosa  ARLeite  MCde Almeida  LMNardin  PCunha  ABCeresér  KMSantin  AGottfried  CSalvador  MKapczinski  FGonçalves  CA Serum S100B and antioxidant enzymes in bipolar patients. J Psychiatr Res 2007;41 (6) 523- 529
PubMed Link to Article
Machado-Vieira  RAndreazza  ACViale  CIZanatto  VCereser  V  Jrda Silva Vargas  RKapczinski  FPortela  LVSouza  DOSalvador  MGentil  V Oxidative stress parameters in unmedicated and treated bipolar subjects during initial manic episode: a possible role for lithium antioxidant effects. Neurosci Lett 2007;421 (1) 33- 36
PubMed Link to Article
Savaş  HAHerken  HYürekli  MUz  ETutkun  HZoroğlu  SSOzen  MECengiz  BAkyol  O Possible role of nitric oxide and adrenomedullin in bipolar affective disorder. Neuropsychobiology 2002;45 (2) 57- 61
PubMed Link to Article
Savas  HAGergerlioglu  HSArmutcu  FHerken  HYilmaz  HRKocoglu  ESelek  STutkun  HZoroglu  SSAkyol  O Elevated serum nitric oxide and superoxide dismutase in euthymic bipolar patients: impact of past episodes. World J Biol Psychiatry 2006;7 (1) 51- 55
PubMed Link to Article
Selek  SSavas  HAGergerlioglu  HSBulbul  FUz  EYumru  M The course of nitric oxide and superoxide dismutase during treatment of bipolar depressive episode. J Affect Disord 2008;107 (1-3) 89- 94
PubMed Link to Article
Andreazza  ACFrey  BNErdtmann  BSalvador  MRombaldi  FSantin  AGonçalves  CAKapczinski  F DNA damage in bipolar disorder. Psychiatry Res 2007;153 (1) 27- 32
PubMed Link to Article
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