The Na,K-ATPase Hypothesis for Bipolar Disorder: Implications of Normal Development

The Potential Role of the Ketogenic Diet in Serious Mental Illness: Current Evidence, Safety, and Practical Advice

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that mimics the physiological state of fasting. The potential therapeutic effects in many chronic conditions have led to the gaining popularity of the KD. The KD has been demonstrated to alleviate inflammation and oxidative stress, modulate the gut microbiota community, and improve metabolic health markers. The modification of these factors has been a potential therapeutic target in serious mental illness (SMI): bipolar disorder, major depressive disorder, and schizophrenia. The number of clinical trials assessing the effect of the KD on SMI is still limited. Preliminary research, predominantly case studies, suggests potential therapeutic effects, including weight gain reduction, improved carbohydrate and lipid metabolism, decrease in disease-related symptoms, increased energy and quality of life, and, in some cases, changes in pharmacotherapy (reduction in number or dosage of medication). However, these findings necessitate further investigation through larger-scale clinical trials. Initiation of the KD should occur in a hospital setting and with strict care of a physician and dietitian due to potential side effects of the diet and the possibility of exacerbating adverse effects of pharmacotherapy. An increasing number of ongoing studies examining the KD's effect on mental disorders highlights its potential role in the adjunctive treatment of SMI.

Ketogenic-Mimicking Diet as a Therapeutic Modality for Bipolar Disorder: Biomechanistic Rationale and Protocol for a Pilot Clinical Trial

There is growing interest in the investigation of ketogenic diets as a potential therapy for bipolar disorder. The overlapping pharmacotherapies utilized for both bipolar disorder and seizures suggest that a mechanistic overlap may exist between these conditions, with fasting and the ketogenic diet representing the most time-proven therapies for seizure control. Recently, preliminary evidence has begun to emerge supporting a potential role for ketogenic diets in treating bipolar disorder. Notably, some patients may struggle to initiate a strict diet in the midst of a mood episode or significant life stressors. The key question addressed by this pilot clinical trial protocol is if benefits can be achieved with a less restrictive diet, as this would allow such an intervention to be accessible for more patients. Recent development of so-called ketone esters, that once ingested is converted to natural ketone bodies, combined with low glycemic index dietary changes has the potential to mimic two foundational components of therapeutic ketosis: high levels of ketones and minimal spiking of glucose/insulin. This pilot clinical trial protocol thus aims to investigate the effect of a 'ketogenic-mimicking diet' (combining supplementation of ketone esters with a low glycemic index dietary intervention) on neural network stability, mood, and biomarker outcomes in the setting of bipolar disorder. Positive findings obtained via this pilot clinical trial protocol may support future target engagement studies of ketogenic-mimicking diets or related ketogenic interventions. A lack of positive findings, in contrast, may justify a focus on more strict dietary interventions for future research.

Gene module regulation in dilated cardiomyopathy and the role of Na/K-ATPase

Dilated cardiomyopathy (DCM) is a major cause of cardiac death and heart transplantation. It has been known that black people have a higher incidence of heart failure and related diseases compared to white people. To identify the relationship between gene expression and cardiac function in DCM patients, we performed pathway analysis and weighted gene co-expression network analysis (WGCNA) using RNA-sequencing data (GSE141910) from the NCBI Gene Expression Omnibus (GEO) database and identified several gene modules that were significantly associated with the left ventricle ejection fraction (LVEF) and DCM phenotype. Genes included in these modules are enriched in three major categories of signaling pathways: fibrosis-related, small molecule transporting-related, and immune response-related. Through consensus analysis, we found that gene modules associated with LVEF in African Americans are almost identical as in Caucasians, suggesting that the two groups may have more common rather than disparate genetic regulations in the etiology of DCM. In addition to the identified modules, we found that the gene expression level of Na/K-ATPase, an important membrane ion transporter, has a strong correlation with the LVEF. These clinical results are consistent with our previous findings and suggest the clinical significance of Na/K-ATPase regulation in DCM.

Pharmacologic Treatment and Management of Bipolar Disorder in Adolescents

INTRODUCTION

The importance of the appropriate therapeutic interventions in children and adolescents with bipolar disorder (BD) cannot be overstated since treatment choices and their consequences may have effects into adulthood.

AREAS COVERED

Randomized clinical trials (RCTs) investigating treatment of mania, bipolar depression, and maintenance in adolescents with BD are reviewed. When RCTs are not available or are inadequate, naturalistic data or open studies are also reviewed.

EXPERT OPINION

Efficacy and safety of pharmaceutical agents in adolescents with BD appear to mirror adults with BD. Lithium/mood stabilizers are preferred first line agents over antipsychotic medications, but the latter are second line agents particularly in bipolar depression. When lithium is used, serum levels approaching 1.0 mEq/L are reasonable since younger people appear to require/tolerate higher levels. Among the antipsychotics, quetiapine appeared to be minimally better than risperidone while risperidone was associated with greater adverse events. Antipsychotics with antidepressant activity in adults, also appear to have antidepressant effects in youths. Use of antidepressants in bipolar depression is generally not recommended although it may be reasonable in specific clinical situations. The similarities between adolescent and adult outcomes suggest that it is reasonable to utilize adult data to aid with clinical decision making in adolescents with BD, especially when pediatric-specific data are unavailable.

Extra-synaptic modulation of GABAA and efficacy in bipolar disorder

BACKGROUND

Bipolar disorder type I is a severe psychiatric condition that leads to significant morbidity and mortality and whose treatment remains suboptimal. Its pathophysiology involves disturbance in the control of ionic fluxes so that when patients are either manic or depressed, the resting membrane potential of neurons is more depolarized than normal. Available mood stabilizers have a shared mechanism of normalizing ion flux by compensating for ionic abnormalities, and normalizing membrane potential.

HYPOTHESIS

Agents that significantly potentiate extrasynaptic GABA_A receptors are expected to be particularly effective in hyperpolarizing resting membrane potential in bipolar patients, thereby normalizing their membrane potential.

DISCUSSION

New neuroactive steroid-like agents are being tested in humans for depression and insomnia. These agents include brexanolone, ganaxolone, and gaboxadol. Brexanolone has been approved for the treatment of postpartum depression, ganaxolone is being studied for treatment-resistant depression, and gaboxadol development for the treatment of insomnia has been abandoned due to narrow therapeutic index. In addition to the current studies, these agents are expected to have particular efficacy in acute and prophylactic management of bipolar I disorder by hyperpolarizing the resting potential of neurons and antagonizing one of the most reproducible demonstrated biologic abnormalities of this illness.

Lithium Preparations in Psychiatry, Addiction Medicine and Neurology. Part II. Biochemical Mechanisms of Its Action

Lithium is the first and the lightest in the series of alkali metals, to which, in addition to lithium, two very biologically important elements – sodium and potassium, as well as trace elements rubidium and cesium, belong. Despite its formal affiliation to the group of alkali metals, lithium, like many other chemical elements of the «atypical» second period of the periodic table (for example, boron), is more similar in its chemical properties not to its counterparts in the group, but to its «diagonal brother» – magnesium. As we will show in this article, the diagonal chemical similarity between lithium and magnesium is of great importance for understanding the mechanisms of its intracellular biochemical action. At the same time, the intragroup chemical similarity of lithium with sodium and potassium is more important for understanding the mechanisms of its absorption, its distribution in the body and its excretion. Despite the 70 years that have passed since John Cade’s discovery of the antimanic effect of lithium, the mechanisms of its therapeutic action are still not completely understood. In the end, it turns out that the mechanism of the therapeutic action of lithium is extremely complex, multicomponent, unique and not imitable. Certain aspects of the mechanism of its action may be compatible with the mechanisms of action of other mood stabilizers, or with the mechanisms of action of so-called «lithium-mimetics», such as ebselen. However, no other drug to date failed to fully reproduce the biochemical effect of lithium on the body.

A continuum of T 2 * components: Flexible fast fraction mapping in sodium MRI

PURPOSE

Parameter mapping in sodium MRI data is challenging due to inherently low SNR and spatial resolution, prompting the need to employ robust models and estimation techniques. This work aims to develop a continuum model of sodium T 2 * -decay to overcome the limitations of the commonly employed bi-exponential models. Estimates of mean T 2 * -decay and fast component fraction in tissue are emergent from the inferred continuum model.

METHODS

A closed-form continuum model was derived assuming a gamma distribution of T 2 * components. Sodium MRI was performed on four healthy human subjects and a phantom consisting of closely packed vials filled with an aqueous solution of varying sodium and agarose concentrations. The continuum model was applied to the phantom and in vivo human multi-echo 7T data. Parameter maps by voxelwise model-fitting were obtained.

RESULTS

The continuum model demonstrated comparable estimation performance to the bi-exponential model. The parameter maps provided improved contrast between tissue structures. The fast component fraction, an indicator of the heterogeneity of localised sodium motion regimes in tissue, was zero in CSF and high in WM structures.

CONCLUSIONS

The continuum distribution model provides high quality, high contrast parameter maps, and informative voxelwise estimates of the relative weighting between fast and slow decay components.

Characterization of a Long Non-Coding RNA, the Antisense RNA of Na/K-ATPase α1 in Human Kidney Cells

Non-coding RNAs are important regulators of protein-coding genes. The current study characterized an antisense long non-coding RNA, ATP1A1-AS1, which is located on the opposite strand of the Na/K-ATPase α1 gene. Our results show that four splice variants are expressed in human adult kidney cells (HK2 cells) and embryonic kidney cells (HEK293 cells). These variants can be detected in both cytosol and nuclear fractions. We also found that the inhibition of DNA methylation has a differential effect on the expression of ATP1A1-AS1 and its sense gene. To investigate the physiological role of this antisense gene, we overexpressed the ATP1A1-AS1 transcripts, and examined their effect on Na/K-ATPase expression and related signaling function in human kidney cells. The results showed that overexpression of the ATP1A1-AS1-203 transcript in HK2 cells reduced the Na/K-ATPase α1 (ATP1A1) gene expression by approximately 20% (p < 0.05), while reducing the Na/K-ATPase α1 protein synthesis by approximately 22% (p < 0.05). Importantly, overexpression of the antisense RNA transcript attenuated ouabain-induced Src activation in HK2 cells. It also inhibited the cell proliferation and potentiated ouabain-induced cell death. These results demonstrate that the ATP1A1-AS1 gene is a moderate negative regulator of Na/K-ATPase α1, and can modulate Na/K-ATPase-related signaling pathways in human kidney cells.

Effects of mood stabilizers on oxidative stress-induced cell death signaling pathways in the brains of rats subjected to the ouabain-induced animal model of mania: Mood stabilizers exert protective effects against ouabain-induced activation of the cell death pathway

The present study aimed to investigate the effects of mood stabilizers, specifically lithium (Li) and valproate (VPA), on mitochondrial superoxide, lipid peroxidation, and proteins involved in cell death signaling pathways in the brains of rats subjected to the ouabain-induced animal model of mania. Wistar rats received Li, VPA, or saline twice a day for 13 days. On the 7th day of treatment, the animals received a single intracerebroventricular injection of ouabain or aCSF. After the ICV injection, the treatment with mood stabilizers continued for 6 additional days. The locomotor activity of rats was measured using the open-field test. In addition, we analyzed oxidative stress parameters, specifically levels of phosphorylated p53 (pp53), BAX and Bcl-2 in the brain of rats by immunoblot. Li and VPA reversed ouabain-related hyperactivity. Ouabain decreased Bcl-2 levels and increased the oxidative stress parameters BAX and pp53 in the brains of rats. Li and VPA improved these ouabain-induced cellular dysfunctions; however, the effects of the mood stabilizers were dependent on the protein and brain region analyzed. These findings suggest that the Na(+)/K(+)-ATPase can be an important link between oxidative damage and the consequent reduction of neuronal and glial density, which are both observed in BD, and that Li and VPA exert protective effects against ouabain-induced activation of the apoptosis pathway.

Possible involvement of membrane lipids peroxidation and oxidation of catalytically essential thiols of the cerebral transmembrane sodium pump as component mechanisms of iron-mediated oxidative stress-linked dysfunction of the pump's activity

The precise molecular events defining the complex role of oxidative stress in the inactivation of the cerebral sodium pump in radical-induced neurodegenerative diseases is yet to be fully clarified and thus still open. Herein we investigated the modulation of the activity of the cerebral transmembrane electrogenic enzyme in Fe²⁺-mediated in vitro oxidative stress model. The results show that Fe²⁺ inhibited the transmembrane enzyme in a concentration dependent manner and this effect was accompanied by a biphasic generation of aldehydic product of lipid peroxidation. While dithiothreitol prevented both Fe²⁺ inhibitory effect on the pump and lipid peroxidation, vitamin E prevented only lipid peroxidation but not inhibition of the pump. Besides, malondialdehyde (MDA) inhibited the pump by a mechanism not related to oxidation of its critical thiols. Apparently, the low activity of the pump in degenerative diseases mediated by Fe²⁺ may involve complex multi-component mechanisms which may partly involve an initial oxidation of the critical thiols of the enzyme directly mediated by Fe²⁺ and during severe progression of such diseases; aldehydic products of lipid peroxidation such as MDA may further exacerbate this inhibitory effect by a mechanism that is likely not related to the oxidation of the catalytically essential thiols of the ouabain-sensitive cerebral electrogenic pump.

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Fe²⁺ evoked lipid peroxidation (LPO) and inhibition of sodium pump (SP) in rat brain.

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However, dithiothreitol prevented both Fe²⁺-mediated LPO and inhibition of SP.

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Conversely, vitamin E prevented only Fe²⁺-mediated LPO but not inhibition of SP.

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Thus Fe²⁺ mediated inactivation of SP likely by oxidizing the essential thiol on SP.

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However, malondialdehyde inhibited SP by a mechanism not related to thiol oxidation.

Effects of ouabain on cytokine/chemokine levels in an animal model of mania

Bipolar disorder (BD) is a chronic and severe psychiatric disorder and despite its importance, little is known about the precise pathophysiology of this disorder. Several studies have reported that inflammation plays a role in the pathogenesis of BD and that cytokines are altered in these patients. Intracerebroventricular (ICV) injection of ouabain (a potent Na(+)/K(+)-ATPase inhibitor) in rats resulted in manic-like effects and it has been widely used as an animal model of bipolar mania. In this study, we assessed the cytokine levels (IL-1β, IL-6, IL-10, TNF-α, CINC-1) in the brain structures (hippocampus, striatum, frontal cortex, amygdala), serum and cerebrospinal fluid (CSF) of rats submitted to an animal model of mania induced by ouabain. Our findings demonstrated that ouabain induced hyperlocomotion in rats. However, the only cytokine that showed alteration was IL-6, which was decreased in the striatum after ouabain administration. In conclusion, despite the ouabain administration in rats be a valid model to study the physiopathology of bipolar mania, it seems that this model was not able to mimic the changes in cytokines observed in bipolar patients.

Inorganic mercury interacts with thiols at the nucleotide and cationic binding sites of the ouabain-sensitive cerebral electrogenic sodium pump

The molecular events leading to neuronal dysfunction often associated with mercury toxicity can be complex and is yet to be fully elucidated. Hence, the present study sought to evaluate the interaction of inorganic mercury (Hg(2+)) with the ouabain-sensitive electrogenic pump in partially purified mammalian brain membrane preparations. The results show that Hg(2+) significantly inhibited the transmembrane enzyme in a concentration dependent manner. In addition, Hg(2+) exerts its inhibitory effect on the activity of the enzyme by interacting with groups at the adenosine triphosphate (ATP), Na(+) and K(+) binding sites. However, preincubation of the enzyme with exogenous monothiols, cysteine, prevented the inhibition of Hg(2+) on the pump's activity suggesting that Hg(2+) may be interacting with the thiols at the nucleotide (ATP) and cationic (Na(+) and K(+)) binding sites. In fact, our data show that Hg(2+) oxidizes sulphydryl groups in cysteine in a time dependent fashion in vitro. Finally, we speculate that the small molecular volume of Hg(2+) in comparison with the substrates (ATP, Na(+) and K(+)) of sodium pump, its possibly high reactivity and strong affinity for thiols may account for its high toxicity towards the membrane bound ouabain-sensitive electrogenic pump.

Evaluation of citrate synthase activity in brain of rats submitted to an animal model of mania induced by ouabain

Bipolar disorder (BD) is a psychiatric disorder characterized by alternating episodes of mania and depression. The intracerebroventricular (i.c.v) administration of ouabain (a Na(+)/K(+)-ATPase inhibitor) in rats has been used as an animal model of mania, because present face, construct and predictive validities. Several studies strongly suggest that mitochondrial dysfunction play a central role in the pathophysiology of BD. Citrate synthase (CS) is an enzyme localized in the mitochondrial matrix and represents one of the most important steps of Krebs cycle. The aim of this study was to investigate CS activity in brain of rats after the administration of ouabain. Adult male Wistar rats received a single i.c.v. administration of ouabain (10(-2) and 10(-3) M) or vehicle (control group). Locomotor activity was measured using the open field task. CS activity was measured in the brain of rats immediately (1 h) and 7 days after ouabain administration. Our results showed that spontaneous locomotion was increased 1 h after ouabain administration, and that the hyperlocomotion persists 7 days after the administration. Moreover, CS activity was inhibited immediately after the administration of ouabain in the prefrontal cortex at the doses of 10(-3) and 10(-2) M. This inhibition remains by 7 days after the administration of ouabain. On the other hand, it was not observed any difference in CS activity in the hippocampus and striatum. Considering that inhibition of CS activity may reflect a mitochondrial dysfunction, it is tempting to speculate that the reduction of brain energy metabolism might be related to the pathophysiology of BD.

Lithium prevents ouabain-induced behavioral changes. Toward an animal model for manic depression

Both mania and bipolar depression have been associated with decrements in the activity of the sodium and potassium-activated adenosine triphosphatase (Na,K-ATPase) membrane pump. Although the role of this observation in the pathophysiology of bipolar illness is unclear, it has been proposed that this defect could be central to the pathogenesis of the illness. In an effort to test this hypothesis, the authors examined the efficacy of lithium pretreatment in attenuating behavioral changes secondary to acute administration of a single intracerebroventricular (i.c.v.) dose of the Na,K-ATPase-inhibiting compound, ouabain, in the Sprague-Dawley rat. Ouabain (10(-3)M) significantly decreased motor activity in automated activity monitors. Lithium pretreatment for 7 d totally prevented this effect. These preliminary data suggest that i.c.v. ouabain administration in the rat may prove to be a viable animal model for bipolar illness.

Leukocyte transmembrane potential in bipolar illness

Abnormalities in ion regulation and distribution are commonly reported in bipolar disorder. In an effort to determine if these alter cellular physiological function, we determined the transmembrane potential (TMP) in mononuclear leukocytes from normal individuals and patients with bipolar illness either during normal phase or manic and hypomanic episodes. TMP was analyzed by flow cytometry using dihexyloxacarbocyanine iodide (DIOC6(3)), a cationic potential sensitive fluorescent dye. A normal range was established from measurements on leukocytes from 5 control individuals. TMP of manic and hypomanic patients was significantly hyperpolarized (P = 0.0036). The TMP of euthymic bipolar individuals was not different from normal controls. Pathologic moods in bipolar illness may be associated with altered cellular membrane physiology.

Lymphoblastoid transmembrane potential in bipolar patients, their siblings, and unrelated healthy comparison subjects

Bipolar illness appears to be characterized by alterations in ionic homeostasis that are related to mood state. This is reflected by reports of altered intracellular sodium and calcium concentrations, altered sodium pump (Na+,K+-adenosine triphosphatase), and calcium pump (Ca2+-adenosine triphosphatase) activity. Recent ex vivo studies with fresh lymphocytes and in vitro studies with cultured lymphoblasts suggest that there may be an enduring trait-related abnormality in Na+,K+-adenosine triphosphatase as well. We have previously found that the lymphocyte transmembrane potential (TMP) varies with mood state. To examine the question of trait-related changes in TMP, we studied TMP of immortalized lymphoblasts from 14 patients with bipolar illness, nine unaffected siblings, and eight normal subjects. TMP was the same in all three groups. These preliminary data suggest that TMP is a state-- rather than a trait-related marker.

An animal model for mania: preliminary results

1. In human bipolar patients mania and bipolar depression are both characterized by decreased membrane Na,K-AtPase activity. Additionally, digoxin neurotoxicity in patients frequently presents with symptoms of mania or depression. 2. These findings suggest that central nervous system Na,K-ATPase inhibition may play a pathophysiologic role in bipolar illness. 3. The authors tested this hypothesis by administering intracerebroventricular (i.c.v.) ouabain to rats at sublethal doses. The authors then measured behavioral activity as total square crossings in an open field. 4. Motoric activity was significantly increased by i.c.v. administration of 5 microliters of ouabain at 10(-3) M. This preliminary study suggests that i.c.v. ouabain administration may provide a useful animal model of mania that is based on observed biochemical changes in humans.

Possible role of endogenous ouabain-like compounds in the pathophysiology of bipolar illness

A large number of studies have documented a mood-state-related decrease in blood cell sodium, potassium-activated adenosine triphosphatase (Na, K-ATPase) activity in acutely ill bipolar patients. While it has been proposed that this enzymatic change may be central to the pathophysiology of bipolar illness, its genesis has remained obscure. Recent advances in the isolation and characterization of endogenously produced ouabain- or digoxin-like compounds suggest a possible mechanism by which these mood-state-related changes can come about. We herein propose that the hypothalamic-pituitary-adrenal dysregulation frequently documented in major mood disorders may underlie a pathological increase in the production of endogenous ouabain-like compounds which excessively suppresses Na, K-ATPase activity and results in pathological mood and energy alteration.