Mitochondrially mediated plasticity in the pathophysiology and treatment of bipolar disorder

The emerging neuroimmune hypothesis of bipolar disorder: An updated overview of neuroimmune and microglial findings

Bipolar disorder (BD) is a severe and multifactorial disease, with onset usually in young adulthood, which follows a progressive course throughout life. Replicated epidemiological studies have suggested inflammatory mechanisms and neuroimmune risk factors as primary contributors to the onset and development of BD. While not all patients display overt markers of inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease and seems to be mood phase dependent, likely explaining the heterogeneity of findings observed in this population. As the brain's immune cells, microglia orchestrate the brain's immune response and play a critical role in maintaining the brain's health across the lifespan. Microglia are also highly sensitive to environmental changes and respond to physiological and pathological events by adapting their functions, structure, and molecular expression. Recently, it has been highlighted that instead of a single population of cells, microglia comprise a heterogeneous community with specialized states adjusted according to the local molecular cues and intercellular interactions. Early evidence has highlighted the contribution of microglia to BD neuropathology, notably for severe outcomes, such as suicidality. However, the roles and diversity of microglial states in this disease are still largely undermined. This review brings an updated overview of current literature on the contribution of neuroimmune risk factors for the onset and progression of BD, the most prominent neuroimmune abnormalities (including biomarker, neuroimaging, ex vivo studies) and the most recent findings of microglial involvement in BD neuropathology. Combining these different shreds of evidence, we aim to propose a unifying hypothesis for BD pathophysiology centered on neuroimmune abnormalities and microglia. Also, we highlight the urgent need to apply novel multi-system biology approaches to characterize the diversity of microglial states and functions involved in this enigmatic disorder, which can open bright perspectives for novel biomarkers and therapeutic discoveries.

Sleep, mood disorders, and the ketogenic diet: potential therapeutic targets for bipolar disorder and schizophrenia

Bipolar disorder and schizophrenia are serious psychiatric conditions that cause a significant reduction in quality of life and shortened life expectancy. Treatments including medications and psychosocial support exist, but many people with these disorders still struggle to participate in society and some are resistant to current therapies. Although the exact pathophysiology of bipolar disorder and schizophrenia remains unclear, increasing evidence supports the role of oxidative stress and redox dysregulation as underlying mechanisms. Oxidative stress is an imbalance between the production of reactive oxygen species generated by metabolic processes and antioxidant systems that can cause damage to lipids, proteins, and DNA. Sleep is a critical regulator of metabolic homeostasis and oxidative stress. Disruption of sleep and circadian rhythms contribute to the onset and progression of bipolar disorder and schizophrenia and these disorders often coexist with sleep disorders. Furthermore, sleep deprivation has been associated with increased oxidative stress and worsening mood symptoms. Dysfunctional brain metabolism can be improved by fatty acid derived ketones as the brain readily uses both ketones and glucose as fuel. Ketones have been helpful in many neurological disorders including epilepsy and Alzheimer's disease. Recent clinical trials using the ketogenic diet suggest positive improvement in symptoms for bipolar disorder and schizophrenia as well. The improvement in psychiatric symptoms from the ketogenic diet is thought to be linked, in part, to restoration of mitochondrial function. These findings encourage further randomized controlled clinical trials, as well as biochemical and mechanistic investigation into the role of metabolism and sleep in psychiatric disorders. This narrative review seeks to clarify the intricate relationship between brain metabolism, sleep, and psychiatric disorders. The review will delve into the initial promising effects of the ketogenic diet on mood stability, examining evidence from both human and animal models of bipolar disorder and schizophrenia. The article concludes with a summary of the current state of affairs and encouragement for future research focused on the role of metabolism and sleep in mood disorders.

Targeting mitophagy for depression amelioration: a novel therapeutic strategy

Major depressive disorder is a global psychiatric condition characterized by persistent low mood and anhedonia, which seriously jeopardizes the physical and mental well-being of affected individuals. While various hypotheses have been proposed to explicate the etiology of depression, the precise pathogenesis and effective treatment of this disorder remain elusive. Mitochondria, as the primary organelles responsible for cellular energy production, possess the ability to meet the essential energy demands of the brain. Research indicated that the accumulation of damaged mitochondria is associated with the onset of depression. Mitophagy, a type of cellular autophagy, specifically targets and removes excess or damaged mitochondria. Emerging evidence demonstrated that mitophagy dysfunction was involved in the progression of depression, and several pharmacological interventions that stimulating mitophagy exerted excellent antidepressant actions. We provided an overview of updated advancements on the regulatory mechanism of mitophagy and the mitophagy abnormality in depressed patients and animals, as well as in cell models of depression. Meanwhile, various therapeutic strategies to restore mitophagy for depression alleviation were also discussed in this review.

Mitochondria dysfunction and bipolar disorder: From pathology to therapy

Bipolar disorder (BD) is one of the major psychiatric diseases in which the impairment of mitochondrial functions has been closely connected or associated with the disease pathologies. Different lines of evidence of the close connection between mitochondria dysfunction and BD were discussed with a particular focus on (1) dysregulation of energy metabolism, (2) effect of genetic variants, (3) oxidative stress, cell death and apoptosis, (4) dysregulated calcium homeostasis and electrophysiology, and (5) current as well as potential treatments targeting at restoring mitochondrial functions. Currently, pharmacological interventions generally provide limited efficacy in preventing relapses or recovery from mania or depression episodes. Thus, understanding mitochondrial pathology in BD will lead to novel agents targeting mitochondrial dysfunction and formulating new effective therapy for BD.

Comparative evaluation of natural neuroprotectives and their combinations on chronic immobilization stress-induced depression in experimental mice

The present study evaluates the potential of neuroprotective phytochemicals-rutin (R), resveratrol (Res), 17β-estradiol (17β-E2), and their different combinations against chronic immobilization stress (CIS)-induced depression-like behaviour in male albino mice. Here, the mice were exposed to stress via immobilization of their four limbs under a restrainer for 6 h daily until 7 days of the induction after 30 min of respective drug treatment in different mice groups. The result found the protective effect of these phytoconstituents and their combinations against CIS-induced depression due to their ability to suppress oxidative stress, restore mitochondria, HPA-axis modulation, neurotransmitter level, stress hormones, and inflammatory markers. Also, the combination drug regimens of these phytoconstituents showed synergistic results in managing the physiological and biochemical features of depression. Thus, these neuroprotective could be utilized well in combination to manage depression-like symptoms during episodic stress. Furthermore, such results could be well justified when administered in polyherbal formulation with these neuroprotective as major components. In addition, an advanced study can be designed at the molecular and epigenetics level using a formulation based on these neuroprotective.

Cellular and molecular mechanisms underlying autism spectrum disorders and associated comorbidities: A pathophysiological review

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders that develop in early life due to interaction between several genetic and environmental factors and lead to alterations in brain function and structure. During the last decades, several mechanisms have been placed to explain the pathogenesis of autism. Unfortunately, these are reported in several studies and reviews which make it difficult to follow by the reader. In addition, some recent molecular mechanisms related to ASD have been unrevealed. This paper revises and highlights the major common molecular mechanisms responsible for the clinical symptoms seen in people with ASD, including the roles of common genetic factors and disorders, neuroinflammation, GABAergic signaling, and alterations in Ca⁺² signaling. Besides, it covers the major molecular mechanisms and signaling pathways involved in initiating the epileptic seizure, including the alterations in the GABAergic and glutamate signaling, vitamin and mineral deficiency, disorders of metabolism, and autoimmunity. Finally, this review also discusses sleep disorder patterns and the molecular mechanisms underlying them.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress–Induced Damage in Patients with Bipolar Disorder

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Maternal Swimming Exercise During Pregnancy Improves Memory Through Enhancing Neurogenesis and Suppressing Apoptosis via Wnt/β-Catenin Pathway in Autistic Mice

Purpose

Wnt pathway is closely related to neurodevelopmental process associated with cognitive function. After administration of valproic acid to the pregnant mice, the effect of swimming exercise of pregnant mice on the memory, neuronal production, and apoptosis of pups was studied in relation with Wnt/β-catenin signaling pathway.

Methods

On day 12 of pregnancy, mice were injected subcutaneously with 400-mg/kg valproic acid. The pregnant mice in the control with swimming exercise group and in the valproic acid injection with swimming exercise group were allowed for swimming for 30 minutes one time per a day, repeated 5 days per a week, during 3 weeks. Step-through avoidance task and Morris water maze task for memory function, immunohistochemistry for 5-bromo-2’-deoxyuridine (BrdU)-positive cells and western blot for brain-derived neurotrophic factor (BDNF), Wnt, β-catenin, Bcl-2 related X protein (Bax), B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 were carried out.

Results

Maternal swimming exercise during pregnancy improved memory function, increased BDNF expression, and neuronal proliferation in the valproic acid injected pups. Maternal swimming exercise during pregnancy suppressed Wnt expression and phosphorylation of β-catenin in the valproic acid injected pups. Maternal swimming exercise inhibited Bax and cleaved caspase-3 expression and increased Bcl-2 expression in the valproic acid injected pups.

Conclusions

Maternal swimming exercise during pregnancy improved memory function by increasing cell proliferation and inhibiting apoptosis through Wnt/β-catenin signaling cascade activation in the valproic acid injected pups. Maternal swimming exercise during pregnancy may have a protective effect on factors that induce autism in the fetus.

The Role of Mitonuclear Incompatibility in Bipolar Disorder Susceptibility and Resilience Against Environmental Stressors

It has been postulated that mitochondrial dysfunction has a significant role in the underlying pathophysiology of bipolar disorder (BD). Mitochondrial functioning plays an important role in regulating synaptic transmission, brain function, and cognition. Neuronal activity is energy dependent and neurons are particularly sensitive to changes in bioenergetic fluctuations, suggesting that mitochondria regulate fundamental aspects of brain function. Vigorous evidence supports the role of mitochondrial dysfunction in the etiology of BD, including dysregulated oxidative phosphorylation, general decrease of energy, altered brain bioenergetics, co-morbidity with mitochondrial disorders, and association with genetic variants in mitochondrial DNA (mtDNA) or nuclear-encoded mitochondrial genes. Despite these advances, the underlying etiology of mitochondrial dysfunction in BD is unclear. A plausible evolutionary explanation is that mitochondrial-nuclear (mitonuclear) incompatibility leads to a desynchronization of machinery required for efficient electron transport and cellular energy production. Approximately 1,200 genes, encoded from both nuclear and mitochondrial genomes, are essential for mitochondrial function. Studies suggest that mitochondrial and nuclear genomes co-evolve, and the coordinated expression of these interacting gene products are essential for optimal organism function. Incompatibilities between mtDNA and nuclear-encoded mitochondrial genes results in inefficiency in electron flow down the respiratory chain, differential oxidative phosphorylation efficiency, increased release of free radicals, altered intracellular Ca²⁺ signaling, and reduction of catalytic sites and ATP production. This review explores the role of mitonuclear incompatibility in BD susceptibility and resilience against environmental stressors.

The Role of Mitochondria in Mood Disorders: From Physiology to Pathophysiology and to Treatment

Mitochondria are cellular organelles involved in several biological processes, especially in energy production. Several studies have found a relationship between mitochondrial dysfunction and mood disorders, such as major depressive disorder and bipolar disorder. Impairments in energy production are found in these disorders together with higher levels of oxidative stress. Recently, many agents capable of enhancing antioxidant defenses or mitochondrial functioning have been studied for the treatment of mood disorders as adjuvant therapy to current pharmacological treatments. A better knowledge of mitochondrial physiology and pathophysiology might allow the identification of new therapeutic targets and the development and study of novel effective therapies to treat these specific mitochondrial impairments. This could be especially beneficial for treatment-resistant patients. In this article, we provide a focused narrative review of the currently available evidence supporting the involvement of mitochondrial dysfunction in mood disorders, the effects of current therapies on mitochondrial functions, and novel targeted therapies acting on mitochondrial pathways that might be useful for the treatment of mood disorders.

Cellular calcium in bipolar disorder: systematic review and meta-analysis

Calcium signalling has long been implicated in bipolar disorder, especially by reports of altered intracellular calcium ion concentrations ([Ca²⁺]). However, the evidence has not been appraised critically. We carried out a systematic review and meta-analysis of studies of cellular calcium indices in bipolar disorder. 2281 records were identified and 117 screened, of which 32 were eligible and 21 were suitable for meta-analyses. The latter each involved up to 642 patients and 404 control subjects. We found that basal free intracellular [Ca²⁺] is increased in bipolar disorder, both in platelets and in lymphocytes. The effect size is 0.55, with an estimated elevation of 29%. It is observed in medication-free patients. It is present in mania and bipolar depression, but data are equivocal for euthymia. Cells from bipolar disorder individuals also show an enhanced [Ca²⁺] response to stimulation with 5-HT or thrombin, by an estimated 25%, with an effect size of 0.63. In studies which included other diagnoses, intracellular basal [Ca²⁺] was higher in bipolar disorder than in unipolar depression, but not significantly different from schizophrenia. Functional parameters of cellular Ca²⁺ (e.g. calcium transients), and neuronal [Ca²⁺], have been much less investigated, and no firm conclusions can be drawn. In summary, there is a robust, medium effect size elevation of basal and stimulated free intracellular [Ca²⁺] in bipolar disorder. The results suggest altered calcium functioning in the disorder, and encourage further investigations into the underlying mechanisms, and the implications for pathophysiology and therapeutics.

Mitochondrial Dysfunction in Blood Platelets of Patients with Manic Episode of Bipolar Disorder

OBJECTIVES

The bipolar affective disorder (BAD) pathophysiology is multifactorial and has not been fully clarified.

METHOD

We measured selected mitochondrial parameters in peripheral blood components. The analyses were performed for patients suffering from a manic episode during remission and were compared to those performed for healthy controls. BAD was clinically evaluated using well-established diagnostic scales and questionnaires. Mitochondrial respiration was examined in intact and permeabilized blood platelets using high-resolution respirometry. The citrate synthase (CS) and electron transport system (ETS) complex (complex I, II, and IV) activities were examined in platelets.

RESULTS

The CS, complex II and complex IV activities were decreased in the BAD patients, complex I activity was increased, and the ratio of complex I to CS was significantly increased. In the intact platelets, respiration after complex I inhibition and residual oxygen consumption were decreased in the BAD patients compared to the healthy controls. In the permeabilized platelets, a decreased ETS capacity was found in the BAD patients. No significant differences were found between BAD patients in mania and remission.

CONCLUSION

Increased complex I activity can be a compensatory mechanism for decreased CS and complex II and IV activities. We conclude that complex I and its abnormal activity contribute to defects in cellular energy metabolism during a manic episode and that the deficiency in the complex's functioning, but not the availability of oxidative phosphorylation substrates, seems to be responsible for the decreased ETS capacity in BAD patients. The observed parameters can be further evaluated as 'trait' markers of BAD.

Important Role of Mitochondria and the Effect of Mood Stabilizers on Mitochondrial Function

Mitochondria primarily serve as source of cellular energy through the Krebs cycle and β-oxidation to generate substrates for oxidative phosphorylation. Redox reactions are used to transfer electrons through a gradient to their final acceptor, oxygen, and to pump hydrogen protons into the intermembrane space. Then, ATP synthase uses the electrochemical gradient to generate adenosine triphosphate (ATP). During these processes, reactive oxygen species (ROS) are generated. ROS are highly reactive molecules with important physiological functions in cellular signaling. Mitochondria play a crucial role in intracellular calcium homeostasis and serve as transient calcium stores. High levels of both, ROS and free cytosolic calcium, can damage mitochondrial and cellular structures and trigger apoptosis. Impaired mitochondrial function has been described in many psychiatric diseases, including mood disorders, in terms of lowered mitochondrial membrane potential, suppressed ATP formation, imbalanced Ca2+ levels and increased ROS levels. In vitro models have indicated that mood stabilizers affect mitochondrial respiratory chain complexes, ROS production, ATP formation, Ca2+ buffering and the antioxidant system. Most studies support the hypothesis that mitochondrial dysfunction is a primary feature of mood disorders. The precise mechanism of action of mood stabilizers remains unknown, but new mitochondrial targets have been proposed for use as mood stabilizers and mitochondrial biomarkers in the evaluation of therapy effectiveness.

Effects of psychosocial and physical stress on lactate and anxiety levels

Both intense physical activity and potent psychosocial stressors increase blood lactate. Raising lactate levels by infusing the chemical can have an anxiogenic effect. Here, we compare the relationship between changes in lactate and anxiety levels resulting from two standardized stressors. We investigated the effects of the Multiple Wingate All-Out Performance Test (WG), a strong physical stressor, and the Trier Social Stress Test (TSST), a well-documented psychosocial stressor, in 32 healthy young men using a crossover design. Before and after each stressor, venous blood was analyzed for lactate levels and the State-Trait-Anxiety Inventory (STAI) was given. Both stressors raised both lactate and anxiety significantly above their baseline levels. While the rise in lactate was much higher for the WG than for the TSST, the rises in anxiety were nearly equal. Individual fitness did not influence the results for lactate or anxiety. No significant relation between lactate and anxiety changes were found. Thus, our results as well as the literature suggest that lactate is an important variable for understanding the impact of sport participation.

Physical exercise ameliorates psychiatric disorders and cognitive dysfunctions by hippocampal mitochondrial function and neuroplasticity in post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a stress-related condition that can be triggered by witnessing or experiencing a life-threatening event, such as a war, natural disaster, terrorist attack, major accident, or assault. PTSD is caused by dysfunction of the hippocampus and causes problems associated with brain functioning, such as anxiety, depression, and cognitive impairment. Exercise is known to have a positive effect on brain function, especially in the hippocampus. In this study, we investigated the effect of aerobic exercise on mitochondrial function and neuroplasticity in the hippocampus as well as behavioral changes in animal models of PTSD. Exposure to severe stress resulted in mitochondrial dysfunction in the hippocampus, including impaired Ca²⁺ homeostasis, an increase in reactive oxygen species such as H₂O₂, a decrease in the O₂ respiration rate, and overexpression of membrane permeability transition pore-related proteins, including voltage-dependent anion channel, adenine nucleotide translocase, and cyclophilin-D. Exposure to extreme stress also decreased neuroplasticity by increasing apoptosis and decreasing the brain-derived neurotrophic factor level and neurogenesis, resulting in increased anxiety, depression, and cognitive impairment. The impairments in mitochondrial function and neuroplasticity in the hippocampus, as well as anxiety, depression, and cognitive impairment, were all improved by exercise. Exercise-induced improvement of the brain-derived neurotrophic factor level in particular might alter mitochondrial function, neuroplasticity, and the rate of apoptosis in the hippocampus. Therefore, exercise might be an important non-pharmacological intervention for the prevention and treatment of the pathobiology of PTSD.

Brain cytochrome-c-oxidase as a marker of mitochondrial function: A pilot study in major depression using NIRS

BACKGROUND

Brain mitochondrial dysfunction is implicated in the pathophysiology of mood disorders. Brain cytochrome-c-oxidase (COX) activity is associated with the mitochondrial function. Near-infrared spectroscopy (NIRS) noninvasively measures oxidized COX (oxCOX) and tissue oxygenation index (TOI) reflecting cerebral blood flow and oxygenation.

METHODS

oxCOX and TOI were assessed in prefrontal cortex (Fp1/2, Brodmann area 10) in patients in a major depressive episode (N = 13) with major depressive disorder (MDD; N = 7) and bipolar disorder (BD; N = 6) compared with the controls (N = 10). One patient with MDD and all the patients with BD were taking medications. Computational modeling estimated oxCOX and TOI related indices of mitochondrial function and cerebral blood flow, respectively.

RESULTS

oxCOX was lower in patients than controls (p = .014) correlating inversely with depression severity (r = -.72; p = .006), driven primarily by lower oxCOX in BD compared with the controls. Computationally modeled mitochondrial parameters of the electron transport chain, such as the nicotinamide adenine dinucleotide ratio (NAD⁺ /NADH; p = .001) and the proton leak rate across the inner mitochondrial membrane (k_lk2 ; p = .008), were also lower in patients and correlated inversely with depression severity. No such effects were found for TOI.

CONCLUSIONS

In this pilot study, oxCOX and related mitochondrial parameters assessed by NIRS indicate an abnormal cerebral metabolic state in mood disorders proportional to depression severity, potentially providing a biomarker of antidepressant effect. Because the effect was driven by the medicated BD group, findings need to be evaluated in a larger, medication-free population.

Association between completed suicide and bipolar disorder: A systematic review of the literature

BACKGROUND

Completed suicide is a major cause of death in bipolar disorder (BD) patients.

OBJECTIVE

The aim of this paper is to provide an overall review of the existing literature of completed suicide in BD patients, including clinical and genetic data DATA SOURCES: We performed a systematic review of English and non-English articles published on MEDLINE/PubMed, PsycInfo and Cochrane database (1970-2017). Additional studies were identified by contacting clinical experts, searching bibliographies, major textbooks and website of World Health Organization. Initially we did a broad search for the association of bipolar disorder and suicide and we were narrowing the search in terms included "bipolar disorder" and "completed suicide".

STUDY SELECTION

Inclusion criteria were articles about completed suicide in patients with BD. Articles exclusively focusing on suicide attempts and suicidal behaviour have been excluded. We used PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) consensus for drafting this systematic review.

RESULTS

The initial search generated 2806 articles and a total of 61 meeting our inclusion criteria. We reviewed epidemiological data, genetic factors, risk factors and treatment of completed suicide in BD. Suicide rates in BD vary between studies but our analyses show that they are approximately 20-30-fold greater than in general population. The highest risk of successful suicide was observed in BD-II subjects. The heritability of completed suicide is about 40% and some genes related to major neurotransmitter systems have been associated with suicide. Lithium is the only treatment that has shown anti-suicide potential.

LIMITATIONS

The most important limitation of the present review is the limited existing literature on completed suicide in BD.

CONCLUSIONS

BD patients are at high risk for suicide. It is possible to identify some factors related to completed suicide, such as early onset, family history of suicide among first-degree relatives, previous attempted suicides, comorbidities and treatment. However it is necessary to promote research on this serious health problem.

Coenzyme Q10 and neuropsychiatric and neurological disorders: relevance for schizophrenia

Objective: Mitochondrial dysfunction has been implicated in the pathophysiology of schizophrenia and other neuropsychiatric disorders. Though the exact mechanisms and clinical implications for this dysfunction are not fully determined, there is a hypothesis that deficiency in coenzyme Q10 (CoQ10) may contribute to mitochondrial impairments and be reflected in cognitive, affective, and energy disturbances in the disorders. CoQ10 is a critical component of the mitochondrial respiratory chain and an essential free radical scavenger, necessary for mitochondrial function. Here, we review the results of CoQ10 supplementation interventions for adults with various neurological and neuropsychiatric disorders and consider the therapeutic potential of CoQ10 supplementation for schizophrenia in light of these studies. Methods: A literature review of randomised controlled trials and open-label studies investigating the effect of CoQ10 as a single intervention in adults with neurological and neuropsychiatric disorders was conducted. Results: CoQ10 supplementation has some positive effects on fatigue, cognitive impairment and affective difficulties in several neurological and neuropsychiatric conditions with associated mitochondrial dysfunction. Discussion: CoQ10 may be of therapeutic value to schizophrenia given evidence of mitochondrial dysfunction in the disorder.

Mitochondrial DNA copy number is associated with psychosis severity and anti-psychotic treatment

Mitochondrial pathology has been implicated in the pathogenesis of psychotic disorders. A few studies have proposed reduced leukocyte mitochondrial DNA (mtDNA) copy number in schizophrenia and bipolar disorder type I, compared to healthy controls. However, it is unknown if mtDNA copy number alteration is driven by psychosis, comorbidity or treatment. Whole blood mtDNA copy number was determined in 594 psychosis patients and corrected for platelet to leukocyte count ratio (mtDNAcn_res). The dependence of mtDNAcn_res on clinical profile, metabolic comorbidity and antipsychotic drug exposure was assessed. mtDNAcn_res was reduced with age (β = −0.210, p < 0.001), use of clozapine (β = −0.110,p = 0.012) and risperidone (β = −0.109,p = 0.014), dependent on prescribed dosage (p = 0.006 and p = 0.026, respectively), and the proportion of life on treatment (p = 0.006). Clozapine (p = 0.0005) and risperidone (p = 0.0126) had a reducing effect on the mtDNA copy number also in stem cell-derived human neurons in vitro at therapeutic plasma levels. For patients not on these drugs, psychosis severity had an effect (β = −0.129, p = 0.017), similar to age (β = −0.159, p = 0.003) and LDL (β = −0.119, p = 0.029) on whole blood mtDNAcn_res. Further research is required to determine if mtDNAcn_res reflects any psychosis-intrinsic mitochondrial changes.

Unraveling the biology of bipolar disorder using induced pluripotent stem-derived neurons

OBJECTIVES

Bipolar disorder has been studied from numerous angles, from pathological studies to large-scale genomic studies, overall making moderate gains toward an understanding of the disorder. With the advancement of induced pluripotent stem (iPS) cell technology, in vitro models based on patient samples are now available that inherently incorporate the complex genetic variants that largely are the basis for this disorder. A number of groups are starting to apply iPS technology to the study of bipolar disorder.

METHODS

We selectively reviewed the literature related to understanding bipolar disorder based on using neurons derived from iPS cells.

RESULTS

So far, most work has used the prototypical iPS cells. However, others have been able to transdifferentiate fibroblasts directly to neurons. Others still have utilized olfactory epithelium tissue as a source of neural-like cells that do not need reprogramming. In general, iPS and related cells can be used for studies of disease pathology, drug discovery, or stem cell therapy.

CONCLUSIONS

Published studies have primarily focused on understanding bipolar disorder pathology, but initial work is also being done to use iPS technology for drug discovery. In terms of disease pathology, some evidence is pointing toward a differentiation defect with more ventral cell types being prominent. Additionally, there is evidence for a calcium signaling defect, a finding that builds on the genome-wide association study results. Continued work with iPS cells will certainly help us understand bipolar disorder and provide a way forward for improved treatments.

The Role of Nutrients in Protecting Mitochondrial Function and Neurotransmitter Signaling: Implications for the Treatment of Depression, PTSD, and Suicidal Behaviors

Numerous studies have linked severe stress to the development of major depressive disorder (MDD) and suicidal behaviors. Furthermore, recent preclinical studies from our laboratory and others have demonstrated that in rodents, chronic stress and the stress hormone cortisol cause oxidative damage to mitochondrial function and membrane lipids in the brain. Mitochondria play a key role in synaptic neurotransmitter signaling by providing adenosine triphosphate (ATP), mediating lipid and protein synthesis, buffering intracellular calcium, and regulating apoptotic and resilience pathways. Membrane lipids are similarly essential to central nervous system (CNS) function because cholesterol, polyunsaturated fatty acids, and sphingolipids form a lipid raft region, a special lipid region on the membrane that mediates neurotransmitter signaling through G-protein-coupled receptors and ion channels. Low serum cholesterol levels, low antioxidant capacity, and abnormal early morning cortisol levels are biomarkers consistently associated with both depression and suicidal behaviors. In this review, we summarize the manner in which nutrients can protect against oxidative damage to mitochondria and lipids in the neuronal circuits associated with cognitive and affective behaviors. These nutrients include ω3 fatty acids, antioxidants (vitamin C and zinc), members of the vitamin B family (Vitamin B12 and folic acid), and magnesium. Accumulating data have shown that these nutrients can enhance neurocognitive function, and may have therapeutic benefits for depression and suicidal behaviors. A growing body of studies suggests the intriguing possibility that regular consumption of these nutrients may help prevent the onset of mood disorders and suicidal behaviors in vulnerable individuals, or significantly augment the therapeutic effect of available antidepressants. These findings have important implications for the health of both military and civilian populations.

Biological hypotheses and biomarkers of bipolar disorder

The most common mood disorders are major depressive disorders and bipolar disorders (BD). The pathophysiology of BD is complex, multifactorial, and not fully understood. Creation of new hypotheses in the field gives impetus for studies and for finding new biomarkers for BD. Conversely, new biomarkers facilitate not only diagnosis of a disorder and monitoring of biological effects of treatment, but also formulation of new hypotheses about the causes and pathophysiology of the BD. BD is characterized by multiple associations between disturbed brain development, neuroplasticity, and chronobiology, caused by: genetic and environmental factors; defects in apoptotic, immune-inflammatory, neurotransmitter, neurotrophin, and calcium-signaling pathways; oxidative and nitrosative stress; cellular bioenergetics; and membrane or vesicular transport. Current biological hypotheses of BD are summarized, including related pathophysiological processes and key biomarkers, which have been associated with changes in genetics, systems of neurotransmitter and neurotrophic factors, neuroinflammation, autoimmunity, cytokines, stress axis activity, chronobiology, oxidative stress, and mitochondrial dysfunctions. Here we also discuss the therapeutic hypotheses and mechanisms of the switch between depressive and manic state.

Increased Brain Lactate During Depressive Episodes and Reversal Effects by Lithium Monotherapy in Drug-Naive Bipolar Disorder: A 3-T 1H-MRS Study

OBJECTIVE

Mitochondrial dysfunction and energy metabolism impairment are key components in the pathophysiology of bipolar disorder (BD) and may involve a shift from aerobic to anaerobic metabolism. Measurement of brain lactate in vivo using proton magnetic resonance spectroscopy (H-MRS) represents an important tool to evaluate mitochondrial and metabolic dysfunction during mood episodes, as well as to monitor treatment response. To date, very few studies have quantified brain lactate in BD. In addition, no study has longitudinally evaluated lactate using H-MRS during depressive episodes or its association with mood stabilizer therapy. This study aimed to evaluate cingulate cortex (CC) lactate using 3-T H-MRS during acute depressive episodes in BD and the possible effects induced by lithium monotherapy.

METHODS

Twenty medication-free outpatients with short length of BD (80% drug-naive) in a current major depressive episode were matched with control subjects. Patients were treated for 6 weeks with lithium monotherapy at therapeutic doses in an open-label trial (blood level, 0.48 ± 0.19 mmol/L). Cingulate cortex lactate was measured before (week 0) and after lithium therapy (week 6) using H-MRS. Antidepressant efficacy was assessed with the 21-item Hamilton Depression Rating Scale as the primary outcome.

RESULTS

Subjects with BD depression showed a significantly higher CC lactate in comparison to control subjects. Furthermore, a significant decrease in CC lactate was observed after 6 weeks of lithium treatment compared with baseline (P = 0.002). CC Lactate levels was associated with family history of mood disorders and plasma lithium levels.

CONCLUSIONS

This is the first report of increased CC lactate in patients with bipolar depression and lower levels after lithium monotherapy for 6 weeks. These findings indicate a shift to anaerobic metabolism and a role for lactate as a state marker during mood episodes. Energy and redox dysfunction may represent key targets for lithium's therapeutic actions.

Psychiatric disorders biochemical pathways unraveled by human brain proteomics

Approximately 25 % of the world population is affected by a mental disorder at some point in their life. Yet, only in the mid-twentieth century a biological cause has been proposed for these diseases. Since then, several studies have been conducted toward a better comprehension of those disorders, and although a strong genetic influence was revealed, the role of these genes in disease mechanism is still unclear. This led most recent studies to focus on the molecular basis of mental disorders. One line of investigation that has risen in the post-genomic era is proteomics, due to its power of revealing proteins and biochemical pathways associated with biological systems. Therefore, this review compiled and analyzed data of differentially expressed proteins, which were found in postmortem brain studies of the three most prevalent psychiatric diseases: schizophrenia, bipolar disorder and major depressive disorders. Overviewing both the proteomic methods used in postmortem brain studies, the most consistent metabolic pathways found altered in these diseases. We have unraveled those disorders share about 21 % of proteins affected, and though most are related to energy metabolism pathways deregulation, the main differences found are 14-3-3-mediated signaling in schizophrenia, mitochondrial dysfunction in bipolar disorder and oxidative phosphorylation in depression.

Mitochondrial Dysfunction in Depression

Abstract: Background

Depression is the most debilitating neuropsychiatric disorder with significant impact on socio-occupational and well being of individual. The exact pathophysiology of depression is still enigmatic though various theories have been put forwarded. There are evidences showing that mitochondrial dysfunction in various brain regions is associated with depression. Recent findings have sparked renewed appreciation for the role of mitochondria in many intracellular processes coupled to synaptic plasticity and cellular resilience. New insights in depression pathophysiology are revolving around the impairment of neuroplasticity. Mitochondria have potential role in ATP production, intracellular Ca²⁺ signalling to establish membrane stability, reactive oxygen species (ROS) balance and to execute the complex processes of neurotransmission and plasticity. So understanding the various concepts of mitochondrial dysfunction in pathogenesis of depression indubitably helps to generate novel and more targeted therapeutic approaches for depression treatment.

Objective

The review was aimed to give a comprehensive insight on role of mitochondrial dysfunction in depression.

Result

Targeting mitochondrial dysfunction and enhancing the mitochondrial functions might act as potential target for the treatment of depression.

Conclusion

Literature cited in this review highly supports the role of mitochondrial dysfunction in depression. As impairment in the mitochondrial functions lead to the generation of various insults that exaggerate the pathogenesis of depression. So, it is useful to study mitochondrial dysfunction in relation to mood disorders, synaptic plasticity, neurogenesis and enhancing the functions of mitochondria might show promiscuous effects in the treatment of depressed patients.

Beyond the therapeutic shackles of the monoamines: New mechanisms in bipolar disorder biology

Multiple novel biological mechanisms putatively involved in the etiology of bipolar disorders are being explored. These include oxidative stress, altered glutamatergic neurotransmission, mitochondrial dysfunction, inflammation, cell signaling, apoptosis and impaired neurogenesis. Important clinical translational potential exists for such mechanisms to help underpin development of novel therapeutics - much needed given limitations of current therapies. These new mechanisms also help improve our understanding of how current therapeutics might exert their effects. Lithium, for example, appears to have antioxidant, immunomodulatory, signaling, anti-apoptotic and neuroprotective properties. Similar properties have been attributed to other mood stabilizers such as valproate, lamotrigine, and quetiapine. Perhaps of greatest translational value has been the recognition of such mechanisms leading to the emergence of novel therapeutics for bipolar disorders. These include the antioxidant N-acetylcysteine, the anti-inflammatory celecoxib, and ketamine - with effects on the glutamatergic system and microglial inhibition. We review these novel mechanisms and emerging therapeutics, and comment on next steps in this space.

Cerebrospinal fluid metabolomics identifies a key role of isocitrate dehydrogenase in bipolar disorder: evidence in support of mitochondrial dysfunction hypothesis

Although evidence for mitochondrial dysfunction in the pathogenesis of bipolar disorder (BD) has been reported, the precise biological basis remains unknown, hampering the search for novel biomarkers. In this study, we performed metabolomics of cerebrospinal fluid (CSF) from male BD patients (n=54) and age-matched male healthy controls (n=40). Subsequently, post-mortem brain analyses, genetic analyses, metabolomics of CSF samples from rats treated with lithium or valproic acid were also performed. After multivariate logistic regression, isocitric acid (isocitrate) levels were significantly higher in the CSF from BD patients than healthy controls. Furthermore, gene expression of two subtypes (IDH3A and IDH3B) of isocitrate dehydrogenase (IDH) in the dorsolateral prefrontal cortex from BD patients was significantly lower than that of controls, although the expression of other genes including, aconitase (ACO1, ACO2), IDH1, IDH2 and IDH3G, were not altered. Moreover, protein expression of IDH3A in the cerebellum from BD patients was higher than that of controls. Genetic analyses showed that IDH genes (IDH1, IDH2, IDH3A, IDH3B) and ACO genes (ACO1, ACO2) were not associated with BD. Chronic (4 weeks) treatment with lithium or valproic acid in rats did not alter CSF levels of isocitrate, and mRNA levels of Idh3a, Idh3b, Aco1 and Aco2 genes in the rat brain. These findings suggest that abnormality in the metabolism of isocitrate by IDH3A in the mitochondria plays a key role in the pathogenesis of BD, supporting the mitochondrial dysfunction hypothesis of BD. Therefore, IDH3 in the citric acid cycle could potentially be a novel therapeutic target for BD.

Low-Level Laser Irradiation Improves Depression-Like Behaviors in Mice

Major depressive disorder (MDD) is one of the leading forms of psychiatric disorders, characterized by aversion to mobility, neurotransmitter deficiency, and energy metabolic decline. Low-level laser therapy (LLLT) has been investigated in a variety of neurodegenerative disorders associated with mitochondrial dysfunction and functional impairments. The goal of this study was to examine the effect of LLLT on depression-like behaviors and to explore the potential mechanism by detecting mitochondrial function following LLLT. Depression models in space restriction mice and Abelson helper integration site-1 (Ahi1) knockout (KO) mice were employed in this work. Our results revealed that LLLT effectively improved depression-like behaviors, in the two depression mice models, by decreasing immobility duration in behavioral despair tests. In addition, ATP biosynthesis and the level of mitochondrial complex IV expression and activity were significantly elevated in prefrontal cortex (PFC) following LLLT. Intriguingly, LLLT has no effects on ATP content and mitochondrial complex I-IV levels in other tested brain regions, hippocampus and hypothalamus. As a whole, these findings shed light on a novel strategy of transcranial LLLT on depression improvement by ameliorating neurotransmitter abnormalities and promoting mitochondrial function in PFC. The present work provides concrete groundwork for further investigation of LLLT for depression treatment.

Mitochondrial dysfunction in bipolar disorder: Evidence, pathophysiology and translational implications

Bipolar disorder (BD) is a chronic psychiatric illness characterized by severe and biphasic changes in mood. Several pathophysiological mechanisms have been hypothesized to underpin the neurobiology of BD, including the presence of mitochondrial dysfunction. A confluence of evidence points to an underlying dysfunction of mitochondria, including decreases in mitochondrial respiration, high-energy phosphates and pH; changes in mitochondrial morphology; increases in mitochondrial DNA polymorphisms; and downregulation of nuclear mRNA molecules and proteins involved in mitochondrial respiration. Mitochondria play a pivotal role in neuronal cell survival or death as regulators of both energy metabolism and cell survival and death pathways. Thus, in this review, we discuss the genetic and physiological components of mitochondria and the evidence for mitochondrial abnormalities in BD. The final part of this review discusses mitochondria as a potential target of therapeutic interventions in BD.

Nucleus accumbens deep-brain stimulation efficacy in ACTH-pretreated rats: alterations in mitochondrial function relate to antidepressant-like effects

Mitochondrial dysfunction has a critical role in the pathophysiology of mood disorders and treatment response. To investigate this, we established an animal model exhibiting a state of antidepressant treatment resistance in male Wistar rats using 21 days of adrenocorticotropic hormone (ACTH) administration (100 μg per day). First, the effect of ACTH treatment on the efficacy of imipramine (10 mg kg(-1)) was investigated alongside its effect on the prefrontal cortex (PFC) mitochondrial function. Second, we examined the mood-regulatory actions of chronic (7 day) high-frequency nucleus accumbens (NAc) deep-brain stimulation (DBS; 130 Hz, 100 μA, 90 μS) and concomitant PFC mitochondrial function. Antidepressant-like responses were assessed in the open field test (OFT) and forced swim test (FST) for both conditions. ACTH pretreatment prevented imipramine-mediated improvement in mobility during the FST (P<0.05). NAc DBS effectively improved FST mobility in ACTH-treated animals (P<0.05). No improvement in mobility was observed for sham control animals (P>0.05). Analyses of PFC mitochondrial function revealed that ACTH-treated animals had decreased capacity for adenosine triphosphate production compared with controls. In contrast, ACTH animals following NAc DBS demonstrated greater mitochondrial function relative to controls. Interestingly, a proportion (30%) of the ACTH-treated animals exhibited heightened locomotor activity in the OFT and exaggerated escape behaviors during the FST, together with general hyperactivity in their home-cage settings. More importantly, the induction of this mania-like phenotype was accompanied by overcompensative increased mitochondrial respiration. Manifestation of a DBS-induced mania-like phenotype in imipramine-resistant animals highlights the potential use of this model in elucidating mechanisms of mood dysregulation.

Neuropathological Mechanisms of Seizures in Autism Spectrum Disorder

This manuscript reviews biological abnormalities shared by autism spectrum disorder (ASD) and epilepsy. Two neuropathological findings are shared by ASD and epilepsy: abnormalities in minicolumn architecture and γ-aminobutyric acid (GABA) neurotransmission. The peripheral neuropil, which is the region that contains the inhibition circuits of the minicolumns, has been found to be decreased in the post-mortem ASD brain. ASD and epilepsy are associated with inhibitory GABA neurotransmission abnormalities including reduced GABA_A and GABA_B subunit expression. These abnormalities can elevate the excitation-to-inhibition balance, resulting in hyperexcitablity of the cortex and, in turn, increase the risk of seizures. Medical abnormalities associated with both epilepsy and ASD are discussed. These include specific genetic syndromes, specific metabolic disorders including disorders of energy metabolism and GABA and glutamate neurotransmission, mineral and vitamin deficiencies, heavy metal exposures and immune dysfunction. Many of these medical abnormalities can result in an elevation of the excitatory-to-inhibitory balance. Fragile X is linked to dysfunction of the mGluR5 receptor and Fragile X, Angelman and Rett syndromes are linked to a reduction in GABA_A receptor expression. Defects in energy metabolism can reduce GABA interneuron function. Both pyridoxine dependent seizures and succinic semialdehyde dehydrogenase deficiency cause GABA deficiencies while urea cycle defects and phenylketonuria cause abnormalities in glutamate neurotransmission. Mineral deficiencies can cause glutamate and GABA neurotransmission abnormalities and heavy metals can cause mitochondrial dysfunction which disrupts GABA metabolism. Thus, both ASD and epilepsy are associated with similar abnormalities that may alter the excitatory-to-inhibitory balance of the cortex. These parallels may explain the high prevalence of epilepsy in ASD and the elevated prevalence of ASD features in individuals with epilepsy.

Mitochondrial biogenesis is required for axonal growth

During early development, neurons undergo complex morphological rearrangements to assemble into neuronal circuits and propagate signals. Rapid growth requires a large quantity of building materials, efficient intracellular transport and also a considerable amount of energy. To produce this energy, the neuron should first generate new mitochondria because the pre-existing mitochondria are unlikely to provide a sufficient acceleration in ATP production. Here, we demonstrate that mitochondrial biogenesis and ATP production are required for axonal growth and neuronal development in cultured rat cortical neurons. We also demonstrate that growth signals activating the CaMKKβ, LKB1-STRAD or TAK1 pathways also co-activate the AMPK-PGC-1α-NRF1 axis leading to the generation of new mitochondria to ensure energy for upcoming growth. In conclusion, our results suggest that neurons are capable of signalling for upcoming energy requirements. Earlier activation of mitochondrial biogenesis through these pathways will accelerate the generation of new mitochondria, thereby ensuring energy-producing capability for when other factors for axonal growth are synthesized.

Anti-inflammatory, antiapoptotic, and antioxidant activity of fluoxetine

Fluoxetine is a selective serotonin uptake inhibitor that has been widely used to determine the neurotransmission of serotonin in the central nervous system. This substance has emerged as the drug of choice for the treatment of depression due to is safer profile, fewer side effects, and greater tolerability. Studies have found the following important functions of fluoxetine related to the central nervous system: neuroprotection; anti-inflammatory properties similar to standard drugs for the treatment of inflammatory conditions; antioxidant properties, contributing to its therapeutic action and an important intracellular mechanism underlying the protective pharmacological effects seen in clinical practice in the treatment of different stress-related adverse health conditions; and antiapoptotic properties, with greater neuron survival and a reduction in apoptosis mediators as well as oxidative substances, such as superoxide dismutase and hydrogen peroxide. The aim of this study was to perform a review of the literature on the important role of fluoxetine in anti-inflammatory, cell survival, and neuron trophicity mechanisms (antiapoptotic properties) as well as its role regarding enzymes of the antioxidant defense system.

Blood metabolomics analysis identifies abnormalities in the citric acid cycle, urea cycle, and amino acid metabolism in bipolar disorder

Background

Bipolar disorder (BD) is a severe and debilitating psychiatric disorder. However, the precise biological basis remains unknown, hampering the search for novel biomarkers. We performed a metabolomics analysis to discover novel peripheral biomarkers for BD.

Methods

We quantified serum levels of 116 metabolites in mood-stabilized male BD patients (n = 54) and age-matched male healthy controls (n = 39).

Results

After multivariate logistic regression, serum levels of pyruvate, N-acetylglutamic acid, α-ketoglutarate, and arginine were significantly higher in BD patients than in healthy controls. Conversely, serum levels of β-alanine, and serine were significantly lower in BD patients than in healthy controls. Chronic (4-weeks) administration of lithium or valproic acid to adult male rats did not alter serum levels of pyruvate, N-acetylglutamic acid, β-alanine, serine, or arginine, but lithium administration significantly increased serum levels of α-ketoglutarate.

Conclusions

The metabolomics analysis demonstrated altered serum levels of pyruvate, N-acetylglutamic acid, β-alanine, serine, and arginine in BD patients.

General significance

The present findings suggest that abnormalities in the citric acid cycle, urea cycle, and amino acid metabolism play a role in the pathogenesis of BD.

•

Metabolomics analysis of serum sample from bipolar disorder (BD) was performed.

•

Pyruvate, N-acetylglutamic acid, α-ketoglutarate, and arginine were higher in BD.

•

β-alanine, and serine were lower in BD patients.

•

Abnormalities in citric acid cycle, urea cycle, and amino acid metabolism in BD.

Pharmacological targeting of redox regulation systems as new therapeutic approach for psychiatric disorders: A literature overview

Redox dysregulation occurs following a disequilibrium between reactive oxygen species (ROS) producing and degrading systems, i.e. mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and nitric oxide synthase (NOS) on one hand and the principal antioxidant system, the glutathione, on the other hand. Increasing recent evidence points towards a pathogenetic role of an altered redox state in the development of several mental disorders, such as anxiety, bipolar disorders, depression, psychosis, autism and post-traumaticstress disorders (PTSD). In this regard, pharmacological targeting of the redox state regulating systems in the brain has been proposed as an innovative and promising therapeutic approach for the treatment of these mental diseases. This review will summarize current knowledge obtained from both pre-clinical and clinical studies in order to descant "lights and shadows" of targeting pharmacologically both the producing and degrading reactive oxygen species (ROS) systems in psychiatric disorders.

Antimanic Treatment With Tamoxifen Affects Brain Chemistry: A Double-Blind, Placebo-Controlled Proton Magnetic Resonance Spectroscopy Study

BACKGROUND

The antimanic efficacy of a protein kinase C (PKC) inhibitor, tamoxifen, has been tested in several clinical trials, all reporting positive results. However, mechanisms underlying the observed clinical effects requires further confirmation through studies of biological markers.

METHODS

We investigated the effect of tamoxifen versus placebo on brain metabolites via a proton (¹H) magnetic resonance spectroscopy (MRS) study. Forty-eight adult bipolar I manic patients (mean Young Mania Rating Scale (YMRS) score of 37.8±5.8) were scanned at baseline and following 3 weeks of double-blind treatment. We hypothesized that manic symptom alleviation would improve the levels of markers associated with brain energy metabolism (creatine plus phosphocreatine [total creatine; tCr]) and neuronal viability (N-acetylaspartate [NAA]).

RESULTS

The YMRS scores decreased from 38.6±4.5 to 20.0±11.1 in the tamoxifen group and increased from 37.0±6.8 to 43.1±7.8 in the placebo group (p<0.001). ¹H MRS measurements revealed a 5.5±13.8% increase in the dorsomedial prefrontal cortex (DMPFC) tCr levels in the tamoxifen group and a 5.3±13.1% decrease in tCr in the placebo group (p=0.027). A significant correlation between the YMRS score change and tCr percent change was observed in the whole group (Spearman ρ=0.341, p=0.029). Both tCr and NAA levels in the responder group were increased by 9.4±15.2% and 6.1±11.7%, whereas levels in the non-responder group were decreased by 2.1±13.2% and 6.5±10.5%, respectively (p<0.05).

CONCLUSIONS

Tamoxifen effectively treated mania while it also increased brain tCr levels, consistent with involvement of both excessive PKC activation and impaired brain energy metabolism in the development of bipolar mania.

CLINICAL TRIAL REGISTRATION

Registry name: ClinicalTrials.gov URL: https://clinicaltrials.gov/ct2/show/NCT00411203?term=NCT00411203&rank=1 Registration number: NCT00411203.

Microendophenotypes of psychiatric disorders: phenotypes of psychiatric disorders at the level of molecular dynamics, synapses, neurons, and neural circuits

Psychiatric disorders are caused not only by genetic factors but also by complicated factors such as environmental ones. Moreover, environmental factors are rarely quantitated as biological and biochemical indicators, making it extremely difficult to understand the pathological conditions of psychiatric disorders as well as their underlying pathogenic mechanisms. Additionally, we have actually no other option but to perform biological studies on postmortem human brains that display features of psychiatric disorders, thereby resulting in a lack of experimental materials to characterize the basic biology of these disorders. From these backgrounds, animal, tissue, or cell models that can be used in basic research are indispensable to understand biologically the pathogenic mechanisms of psychiatric disorders. In this review, we discuss the importance of microendophenotypes of psychiatric disorders, i.e., phenotypes at the level of molecular dynamics, neurons, synapses, and neural circuits, as targets of basic research on these disorders.

Anterior cingulate Glutamate-Glutamine cycle metabolites are altered in euthymic bipolar I disorder

Bipolar disorder (BD) has been consistently associated with abnormalities in the Glutamate/GABA-Glutamine cycle. Magnetic resonance spectroscopy (MRS) studies have reported increased brain Glutamate (Glu) and Glx (Glu+Glutamine) in subjects with BD. However, data on separate measures of GABA and Glutamine (Gln) in BD are sparse due to overlapping resonant signals. The development of new sequence methods in the quantification of these metabolites has allowed a better understanding of the Glu/GABA-Gln cycle but data on this field of research remains sparse in BD. Eighty-eight subjects (50 euthymic BD and 38 HC) underwent 3T proton magnetic resonance spectroscopy (1H MRS) in the anterior cingulate cortex (ACC; 2×2×4.5cm(3)) using a two-dimensional JPRESS sequence. GABA, Glutamine (Gln) and Glutamate (Glu) were quantified with the ProFit program. Using image segmentation and known creatine (Cre) concentrations for white and grey matter, metabolite concentrations were calculated for the excited MRS voxel. GABA levels did not differ between groups. Gln level was higher in euthymic BD patients than in healthy controls. The Glu level and Glu/Gln ratio were lower in BD patients than in controls. The use of anticonvulsants was associated with Gln increase but did not affect Glu or Glu/Gln. Neither lithium nor antipsychotic use influenced metabolite levels. The ACC MRS findings indicate that the glutamatergic function in euthymic medicated BD patients is altered relative to controls. Whether this feature is a metabolic signature of euthymic BD subjects should be the focus of future studies.

Abnormal high-energy phosphate molecule metabolism during regional brain activation in patients with bipolar disorder

Converging evidence suggests bioenergetic abnormalities in bipolar disorder (BD). In the brain, phosphocreatine (PCr) acts a reservoir of high-energy phosphate (HEP) bonds, and creatine kinases (CK) catalyze the transfer of HEP from adenosine triphosphate (ATP) to PCr and from PCr back to ATP, at times of increased need. This study examined the activity of this mechanism in BD by measuring the levels of HEP molecules during a stimulus paradigm that increased local energy demand. Twenty-three patients diagnosed with BD-I and 22 healthy controls (HC) were included. Levels of phosphorus metabolites were measured at baseline and during visual stimulation in the occipital lobe using (31)P magnetic resonance spectroscopy at 4T. Changes in metabolite levels showed different patterns between the groups. During stimulation, HC had significant reductions in PCr but not in ATP, as expected. In contrast, BD patients had significant reductions in ATP but not in PCr. In addition, PCr/ATP ratio was lower at baseline in patients, and there was a higher change in this measure during stimulation. This pattern suggests a disease-related failure to replenish ATP from PCr through CK enzyme catalysis during tissue activation. Further studies measuring the CK flux in BD are required to confirm and extend this finding.

Levetiracetam, Calcium Antagonism, and Bipolar Disorder

Hyperactive intracellular calcium ion (Ca) signaling in peripheral cells has been a reliable finding in bipolar disorder. Some established mood stabilizing medications, such as lithium and carbamazepine, have been found to normalize elevated intracellular Ca concentrations ([Ca]i) in platelets and lymphocytes from bipolar disorder patients, and some medications the primary effect of which is to attenuate increased [Ca]i have been reported to have mood stabilizing properties.Hyperactive intracellular Ca signaling has also been implicated in epilepsy, and some anticonvulsants have calcium antagonist properties. This study demonstrated that levetiracetam, an anticonvulsant that has been shown to block N and P/Q-type calcium channels in animal studies does not alter elevated [Ca]i in blood platelets of patients with bipolar disorder. Review of published clinical trials revealed no controlled evidence of efficacy as a mood stabilizer.This study underscores the possibility that pharmacologic actions of a medication in animals and normal subjects may not necessarily predict its pharmacologic or clinical effects in actual patients. Effects of treatments on pathophysiology that is demonstrated in clinical subtypes may be more likely to predict effectiveness in those subtypes than choosing medications based on structural similarities to established treatments.

Lithium and Valproate Levels Do Not Correlate with Ketamine's Antidepressant Efficacy in Treatment-Resistant Bipolar Depression

Ketamine and lithium both inhibit glycogen synthase kinase 3. In addition, lithium and ketamine have synergistic antidepressant-like effects at individually subeffective doses in rodents. We hypothesized that ketamine's antidepressant effects would be improved by therapeutic doses of lithium versus valproate and that serum lithium levels would positively correlate with ketamine's antidepressant efficacy. Thirty-six patients with treatment-resistant bipolar depression maintained on therapeutic-dose lithium (n = 23, 0.79 ± 0.15 mEq/L) or valproate (n = 13, 79.6 ± 12.4 mg/mL) received 0.5 mg/kg ketamine infusion in a randomized, double-blind, placebo-controlled, crossover trial. The primary depression outcome measure-the Montgomery-Åsberg Depression Rating Scale (MADRS)-was assessed before infusion and at numerous postinfusion time points. Both lithium (F 1,118 = 152.08, p < 0.001, and d = 2.27) and valproate (F 1,128 = 20.12, p < 0.001, and d = 0.79) significantly improved depressive symptoms, but no statistically significant difference was observed between mood stabilizer groups (F 1,28 = 2.51, p = 0.12, and d = 0.60). Serum lithium and valproate levels did not correlate with ketamine's antidepressant efficacy. Although the study was potentially underpowered, our results suggest that lithium may not potentiate ketamine's antidepressant efficacy in treatment-resistant bipolar depression.

Mechanisms of chemotherapy-induced behavioral toxicities

While chemotherapeutic agents have yielded relative success in the treatment of cancer, patients are often plagued with unwanted and even debilitating side-effects from the treatment which can lead to dose reduction or even cessation of treatment. Common side effects (symptoms) of chemotherapy include (i) cognitive deficiencies such as problems with attention, memory and executive functioning; (ii) fatigue and motivational deficit; and (iii) neuropathy. These symptoms often develop during treatment but can remain even after cessation of chemotherapy, severely impacting long-term quality of life. Little is known about the underlying mechanisms responsible for the development of these behavioral toxicities, however, neuroinflammation is widely considered to be one of the major mechanisms responsible for chemotherapy-induced symptoms. Here, we critically assess what is known in regards to the role of neuroinflammation in chemotherapy-induced symptoms. We also argue that, based on the available evidence, neuroinflammation is unlikely the only mechanism involved in the pathogenesis of chemotherapy-induced behavioral toxicities. We evaluate two other putative candidate mechanisms. To this end we discuss the mediating role of damage-associated molecular patterns (DAMPs) activated in response to chemotherapy-induced cellular damage. We also review the literature with respect to possible alternative mechanisms such as a chemotherapy-induced change in the bioenergetic status of the tissue involving changes in mitochondrial function in relation to chemotherapy-induced behavioral toxicities. Understanding the mechanisms that underlie the emergence of fatigue, neuropathy, and cognitive difficulties is vital to better treatment and long-term survival of cancer patients.

Effects of Mood Stabilizers on Brain Energy Metabolism in Mice Submitted to an Animal Model of Mania Induced by Paradoxical Sleep Deprivation

There is a body of evidence suggesting that mitochondrial dysfunction is involved in bipolar disorder (BD) pathogenesis. Studies suggest that abnormalities in circadian cycles are involved in the pathophysiology of affective disorders; paradoxical sleep deprivation (PSD) induces hyperlocomotion in mice. Thus, the present study aims to investigate the effects of lithium (Li) and valproate (VPA) in an animal model of mania induced by PSD for 96 h. PSD increased exploratory activity, and mood stabilizers prevented PSD-induced behavioral effects. PSD also induced a significant decrease in the activity of complex II-III in hippocampus and striatum; complex IV activity was decreased in prefrontal cortex, cerebellum, hippocampus, striatum and cerebral cortex. Additionally, VPA administration was able to prevent PSD-induced inhibition of complex II-III and IV activities in prefrontal cortex, cerebellum, hippocampus, striatum and cerebral cortex, whereas Li administration prevented PSD-induced inhibition only in prefrontal cortex and hippocampus. Regarding the enzymes of Krebs cycle, only citrate synthase activity was increased by PSD in prefrontal cortex. We also found a similar effect in creatine kinase, an important enzyme that acts in the buffering of ATP levels in brain; its activity was increased in prefrontal cortex, hippocampus and cerebral cortex. These results are consistent with the connection of mitochondrial dysfunction and hyperactivity in BD and suggest that the present model fulfills adequate face, construct and predictive validity as an animal model of mania.

Glial pathology in bipolar disorder: potential therapeutic implications

Bipolar disorder (BD) is a chronic and severe mental disorder with recurrent episodes of mania and depression. In addition to neuronal alterations, accumulating evidences have revealed the importance of glial system in pathophysiology and phenotype of the illness. Postmortem studies have repeatedly demonstrated the alterations in glial cells and its functions in patients with BD. The activated microglia and inflammatory cytokines are proposed to be the potential biomarkers that may help to predict disease exacerbation in BD. On the other hand, anti-BD drugs have been shown to produce profound effects on glial activity, which not only contributes to the therapeutic efficacy, but may also provide a potential target for the drug development of BD. We will focus on the recent development of glial abnormalities and potential therapeutic benefits targeted to glial modulation in BD.