Molecular basis of lithium action: integration of lithium-responsive signaling and gene expression networks

Lithium normalizes ASD-related neuronal, synaptic, and behavioral phenotypes in DYRK1A-knockin mice

Dyrk1A deficiency is linked to various neurodevelopmental disorders, including developmental delays, intellectual disability (ID) and autism spectrum disorders (ASD). Haploinsufficiency of Dyrk1a in mice reportedly leads to ASD-related phenotypes. However, the key pathological mechanisms remain unclear and human DYRK1A mutations remain uncharacterized in mice. Here, we generated and studied Dyrk1a-knockin mice carrying a human ASD patient mutation (Ile48LysfsX2; Dyrk1a-I48K mice). These mice display severe microcephaly, social and cognitive deficits, dendritic shrinkage, excitatory synaptic deficits, and altered phospho-proteomic patterns enriched for multiple signaling pathways and synaptic proteins. Early chronic lithium treatment of newborn mutant mice rescues the brain volume, behavior, dendritic, synaptic, and signaling/synapse phospho-proteomic phenotypes at juvenile and adult stages. These results suggest that signaling/synaptic alterations contribute to the phenotypic alterations seen in Dyrk1a-I48K mice, and that early correction of these alterations by lithium treatment has long-lasting effects in preventing juvenile and adult-stage phenotypes.

MARK2 variants cause autism spectrum disorder via the downregulation of WNT/β-catenin signaling pathway

Microtubule affinity-regulating kinase 2 (MARK2) contributes to establishing neuronal polarity and developing dendritic spines. Although large-scale sequencing studies have associated MARK2 variants with autism spectrum disorder (ASD), the clinical features and variant spectrum in affected individuals with MARK2 variants, early developmental phenotypes in mutant human neurons, and the pathogenic mechanism underlying effects on neuronal development have remained unclear. Here, we report 31 individuals with MARK2 variants and presenting with ASD, other neurodevelopmental disorders, and distinctive facial features. Loss-of-function (LoF) variants predominate (81%) in affected individuals, while computational analysis and in vitro expression assay of missense variants supported the effect of MARK2 loss. Using proband-derived and CRISPR-engineered isogenic induced pluripotent stem cells (iPSCs), we show that MARK2 loss leads to early neuronal developmental and functional deficits, including anomalous polarity and dis-organization in neural rosettes, as well as imbalanced proliferation and differentiation in neural progenitor cells (NPCs). Mark2+/- mice showed abnormal cortical formation and partition and ASD-like behavior. Through the use of RNA sequencing (RNA-seq) and lithium treatment, we link MARK2 loss to downregulation of the WNT/β-catenin signaling pathway and identify lithium as a potential drug for treating MARK2-associated ASD.

Intracellular effects of lithium in aging neurons

Lithium therapy received approval during the 1970s, and it has been used for its antidepressant, antimanic, and anti-suicidal effects for acute and long-term prophylaxis and treatment of bipolar disorder (BPD). These properties have been well established; however, the molecular and cellular mechanisms remain controversial. In the past few years, many studies demonstrated that at the cellular level, lithium acts as a regulator of neurogenesis, aging, and Ca2+ homeostasis. At the molecular level, lithium modulates aging by inhibiting glycogen synthase kinase-3β (GSK-3β), and the phosphatidylinositol (PI) cycle; latter, lithium specifically inhibits inositol production, acting as a non-competitive inhibitor of inositol monophosphatase (IMPase). Mitochondria and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) have been related to lithium activity, and its regulation is mediated by GSK-3β degradation and inhibition. Lithium also impacts Ca2+ homeostasis in the mitochondria modulating the function of the lithium-permeable mitochondrial Na+-Ca2+exchanger (NCLX), affecting Ca2+ efflux from the mitochondrial matrix to the endoplasmic reticulum (ER). A close relationship between the protease Omi, GSK-3β, and PGC-1α has also been established. The purpose of this review is to summarize some of the intracellular mechanisms related to lithium activity and how, through them, neuronal aging could be controlled.

Primary cilia suppress the fibrotic activity of atrial fibroblasts from patients with atrial fibrillation in vitro

Atrial fibrosis serves as an arrhythmogenic substrate in atrial fibrillation (AF) and contributes to AF persistence. Treating atrial fibrosis is challenging because atrial fibroblast activity is multifactorial. We hypothesized that the primary cilium regulates the profibrotic response of AF atrial fibroblasts, and explored therapeutic potentials of targeting primary cilia to treat fibrosis in AF. We included 25 patients without AF (non-AF) and 26 persistent AF patients (AF). Immunohistochemistry using a subset of the patients (non-AF: n = 10, AF: n = 10) showed less ciliated fibroblasts in AF versus non-AF. Acetylated α-tubulin protein levels were decreased in AF, while the gene expressions of AURKA and NEDD9 were highly increased in AF patients' left atrium. Loss of primary cilia in human atrial fibroblasts through IFT88 knockdown enhanced expression of ECM genes, including FN1 and COL1A1. Remarkably, restoration or elongation of primary cilia by an AURKA selective inhibitor or lithium chloride, respectively, prevented the increased expression of ECM genes induced by different profibrotic cytokines in atrial fibroblasts of AF patients. Our data reveal a novel mechanism underlying fibrotic substrate formation via primary cilia loss in AF atrial fibroblasts and suggest a therapeutic potential for abrogating atrial fibrosis by restoring primary cilia.

Li-Mg-Si bioceramics provide a dynamic immuno-modulatory and repair-supportive microenvironment for peripheral nerve regeneration

Biomaterials can modulate the local immune and repair-supportive microenvironments to promote peripheral nerve regeneration. Inorganic bioceramics have been widely used for regulating tissue regeneration and local immune response. However, little is known on whether inorganic bioceramics can have potential for enhancing peripheral nerve regeneration and what are the mechanisms underlying their actions. Here, the inorganic lithium-magnesium-silicon (Li-Mg-Si, LMS) bioceramics containing scaffolds are fabricated and characterized. The LMS-containing scaffolds had no cytotoxicity against rat Schwann cells (SCs), but promoted their migration and differentiation towards a remyelination state by up-regulating the expression of neurotrophic factors in a β-catenin-dependent manner. Furthermore, using single cell-sequencing, we showed that LMS-containing scaffolds promoted macrophage polarization towards the pro-regenerative M2-like cells, which subsequently facilitated the migration and differentiation of SCs. Moreover, implantation with the LMS-containing nerve guidance conduits (NGCs) increased the frequency of M2-like macrophage infiltration and enhanced nerve regeneration and motor functional recovery in a rat model of sciatic nerve injury. Collectively, these findings indicated that the inorganic LMS bioceramics offered a potential strategy for enhancing peripheral nerve regeneration by modulating the immune microenvironment and promoting SCs remyelination.

Transcriptomics and miRNomics data integration in lymphoblastoid cells highlights the key role of immune-related functions in lithium treatment response in Bipolar disorder

BACKGROUND

Bipolar Disorder (BD) is a complex mental disease characterized by recurrent episodes of mania and depression. Lithium (Li) represents the mainstay of BD pharmacotherapy, despite the narrow therapeutic index and the high variability in treatment response. However, although several studies have been conducted, the molecular mechanisms underlying Li therapeutic effects remain unclear.

METHODS

In order to identify molecular signatures and biological pathways associated with Li treatment response, we conducted transcriptome and miRNome microarray analyses on lymphoblastoid cell lines (LCLs) from 20 patients diagnosed with BD classified as Li responders (n = 11) or non-responders (n = 9).

RESULTS

We found 335 mRNAs and 77 microRNAs (miRNAs) significantly modulated in BD responders versus non-responders. Interestingly, pathway and network analyses on these differentially expressed molecules suggested a modulatory effect of Li on several immune-related functions. Indeed, among the functional molecular nodes, we found NF-κB and TNF. Moreover, networks related to these molecules resulted overall inhibited in BD responder patients, suggesting anti-inflammatory properties of Li. From the integrative analysis between transcriptomics and miRNomics data carried out using miRComb R package on the same samples from patients diagnosed with BD, we found 97 significantly and negatively correlated mRNA-miRNA pairs, mainly involved in inflammatory/immune response.

CONCLUSIONS

Our results highlight that Li exerts modulatory effects on immune-related functions and that epigenetic mechanisms, especially miRNAs, can influence the modulation of different genes and pathways involved in Li response. Moreover, our data suggest the potentiality to integrate data coming from different high-throughput approaches as a tool to prioritize genes and pathways.

LiCl treatment leads to long-term restoration of spine maturation and synaptogenesis in adult Tbr1 mutants

Background

Tbr1 encodes a T-box transcription factor and is considered a high confidence autism spectrum disorder (ASD) gene. Tbr1 is expressed in the postmitotic excitatory neurons of the deep neocortical layers 5 and 6. Postnatally and neonatally, Tbr1 conditional mutants (CKOs) have immature dendritic spines and reduced synaptic density. However, an understanding of Tbr1’s function in the adult mouse brain remains elusive.

Methods

We used conditional mutagenesis to interrogate Tbr1’s function in cortical layers 5 and 6 of the adult mouse cortex.

Results

Adult Tbr1 CKO mutants have dendritic spine and synaptic deficits as well as reduced frequency of mEPSCs and mIPSCs. LiCl, a WNT signaling agonist, robustly rescues the dendritic spine maturation, synaptic defects, and excitatory and inhibitory synaptic transmission deficits.

Conclusions

LiCl treatment could be used as a therapeutic approach for some cases of ASD with deficits in synaptic transmission.

Lithium and Erectile Dysfunction: An Overview

Lithium has been a mainstay of therapy for patients with bipolar disorders for several decades. However, it may exert a variety of adverse effects that can affect patients' compliance. Sexual and erectile dysfunction has been reported in several studies by patients who take lithium as monotherapy or combined with other psychotherapeutic agents. The exact mechanisms underlying such side effects of lithium are not completely understood. It seems that both central and peripheral mechanisms are involved in the lithium-related sexual dysfunction. Here, we had an overview of the epidemiology of lithium-related sexual and erectile dysfunction in previous clinical studies as well as possible pathologic pathways that could be involved in this adverse effect of lithium based on the previous preclinical studies. Understanding such mechanisms could potentially open a new avenue for therapies that can overcome lithium-related sexual dysfunction and improve patients' adherence to the medication intake.

Trinuclear Calcium Site in the C2 Domain of PKCα/γ Is Prone to Lithium Attack

Lithium (Li⁺) is the first-line therapy for bipolar disorder and a candidate drug for various diseases such as amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Despite being the captivating subject of many studies, the mechanism of lithium's therapeutic action remains unclear. To date, it has been shown that Li⁺ competes with Mg²⁺ and Na⁺ to normalize the activity of inositol and neurotransmitter-related signaling proteins, respectively. Furthermore, Li⁺ may co-bind with Mg²⁺-loaded adenosine or guanosine triphosphate to alter the complex's susceptibility to hydrolysis and mediate cellular signaling. Bipolar disorder patients exhibit abnormally high cytosolic Ca²⁺ levels and protein kinase C (PKC) hyperactivity that can be downregulated by long-term Li⁺ treatment. However, the possibility that monovalent Li⁺ could displace the bulkier divalent Ca²⁺ and inhibit PKC activity has not been considered. Here, using density functional theory calculations combined with continuum dielectric methods, we show that Li⁺ may displace the native dication from the positively charged trinuclear site in the C2 domain of cytosolic PKCα/γ. This would affect the membrane-docking ability of cytosolic PKCα/γ and reduce the abnormally high membrane-associated active PKCα/γ levels, thus downregulating the PKC hyperactivity found in bipolar patients.

Chronic lithium treatment alters the excitatory/ inhibitory balance of synaptic networks and reduces mGluR5-PKC signalling in mouse cortical neurons

Background

Bipolar disorder is characterized by cyclical alternation between mania and depression, often comorbid with psychosis and suicide. Compared with other medications, the mood stabilizer lithium is the most effective treatment for the prevention of manic and depressive episodes. However, the pathophysiology of bipolar disorder and lithium’s mode of action are yet to be fully understood. Evidence suggests a change in the balance of excitatory and inhibitory activity, favouring excitation in bipolar disorder. In the present study, we sought to establish a holistic understanding of the neuronal consequences of lithium exposure in mouse cortical neurons, and to identify underlying mechanisms of action.

Methods

We used a range of technical approaches to determine the effects of acute and chronic lithium treatment on mature mouse cortical neurons. We combined RNA screening and biochemical and electrophysiological approaches with confocal immunofluorescence and live-cell calcium imaging.

Results

We found that only chronic lithium treatment significantly reduced intracellular calcium flux, specifically by activating metabotropic glutamatergic receptor 5. This was associated with altered phosphorylation of protein kinase C and glycogen synthase kinase 3, reduced neuronal excitability and several alterations to synapse function. Consequently, lithium treatment shifts the excitatory–inhibitory balance toward inhibition.

Limitations

The mechanisms we identified should be validated in future by similar experiments in whole animals and human neurons.

Conclusion

Together, the results revealed how lithium dampens neuronal excitability and the activity of the glutamatergic network, both of which are predicted to be overactive in the manic phase of bipolar disorder. Our working model of lithium action enables the development of targeted strategies to restore the balance of overactive networks, mimicking the therapeutic benefits of lithium but with reduced toxicity.

Enhancing WNT Signaling Restores Cortical Neuronal Spine Maturation and Synaptogenesis in Tbr1 Mutants

Tbr1 is a high-confidence autism spectrum disorder (ASD) gene encoding a transcription factor with distinct pre- and postnatal functions. Postnatally, Tbr1 conditional knockout (CKO) mutants and constitutive heterozygotes have immature dendritic spines and reduced synaptic density. Tbr1 regulates expression of several genes that underlie synaptic defects, including a kinesin (Kif1a) and a WNT-signaling ligand (Wnt7b). Furthermore, Tbr1 mutant corticothalamic neurons have reduced thalamic axonal arborization. LiCl and a GSK3β inhibitor, two WNT-signaling agonists, robustly rescue the dendritic spines and the synaptic and axonal defects, suggesting that this could have relevance for therapeutic approaches in some forms of ASD.

Fazel Darbandi et al. demonstrate that TBR1 directly regulates transcriptional circuits in cortical layers 5 and 6, which promote dendritic spine and synaptic density. Enhancing WNT signaling rescues dendritic spine maturation and synaptogenesis defects in Tbr1 mutants. These results provide insights into mechanisms that underlie ASD pathophysiology.

Microdose Lithium Protects against Pancreatic Islet Destruction and Renal Impairment in Streptozotocin-Elicited Diabetes

Psychiatric use of lithium has been associated with hypoglycemic effects, but its effect on type 1 diabetes mellitus (T1D) is unknown. In streptozotocin (STZ) induced murine models of T1D, microdose lithium therapy improved hyperglycemia, attenuated body weight loss and prevented early signs of diabetic kidney injury. This beneficial effect was associated with preservation of pancreatic islet histology and β-cell production of insulin as well as mitigated oxidative damage of islets. Mechanistically, lithium in islets cells induced inhibitory phosphorylation of glycogen synthase kinase 3β (GSK3β), the major molecular target of lithium that has been recently implicated in non-canonical regulation of Nrf2 activity. In turn, Nrf2 antioxidant response was potentiated in islets, marked by nuclear translocation of Nrf2 and augmented expression of its target antioxidant enzyme heme oxygenase 1 (HO-1). Conversely, cotreatment with trigonelline, a selective blockade of Nrf2, offset the lithium enhanced Nrf2 antioxidant response in islets, blunted the protective effect of lithium on pancreatic islets and β-cells, and abolished the hypoglycemic activity of lithium in STZ-injured mice. Collectively, our findings suggest that microdose lithium confers a protective effect on islet β-cells via targeting the GSK3β-regulated Nrf2 antioxidant response and thereby ameliorates T1D and its related kidney impairment.

Lithium-associated hyperparathyroidism

Lithium is a mood stabiliser widely used in the treatment and prophylaxis of mania, bipolar disorders and recurrent depression. Treatment with lithium can give rise to various endocrine and metabolic abnormalities, including thyroid dysfunction, nephrogenic diabetes insipidus and hypercalcaemia. Lithium may induce hypercalcaemia through both acute and chronic effects. The initial acute effects are potentially reversible and occur as a result of lithium's action on the calcium-sensing receptor pathway and glycogen synthase kinase 3, giving rise to a biochemical picture similar to that seen in familial hypocalciuric hypercalcaemia. In the long term, chronic lithium therapy leads to permanent changes within the parathyroid glands by either unmasking hyperparathyroidism in patients with a subclinical parathyroid adenoma or possibly by initiating multiglandular hyperparathyroidism. The latter biochemical picture is identical to that of primary hyperparathyroidism. Lithium-associated hyperparathyroidism, especially in patients on chronic lithium therapy, is associated with increased morbidity. Hence, regular monitoring of calcium levels in patients on lithium therapy is of paramount importance as early recognition of lithium-associated hyperparathyroidism can improve outcomes. This review focuses on the definition, pathophysiology, presentation, investigations and management of lithium-associated hyperparathyroidism.

Decreased motor impulsivity following chronic lithium treatment in male rats is associated with reduced levels of pro-inflammatory cytokines in the orbitofrontal cortex

Lithium's efficacy in reducing both symptom severity in bipolar disorder (BD) and suicide risk across clinical populations may reflect its ability to reduce impulsivity. Changes in immune markers are associated with BD and suicidality yet their exact role in symptom expression remains unknown. Evidence also suggests that lithium may decrease levels of pro-inflammatory cytokines in the periphery and central nervous system, and that such changes are related to its therapeutic efficacy. However, issues of cause and effect are hard to infer from clinical data alone. Here, we investigated the effects of chronic dietary lithium treatment on rats' performance of the 5-Choice Serial Reaction Time Task (5CSRTT), a well-validated operant behavioural task measuring aspects of impulsivity, attention and motivation. Male Long-Evans rats received a diet supplemented with 0.3% LiCl (n = 13), or the equivalent control diet (n = 16), during behavioural testing. Blood and brain tissue samples were assayed for a wide range of cytokines once any changes in impulsivity became significant. After 12 weeks, chronic lithium treatment reduced levels of motor impulsivity, as indexed by premature responses in the 5CSRTT; measures of sustained attention and motivation were unaffected. Plasma levels of IL-1β, IL-10 and RANTES (CCL-5) were reduced in lithium-treated rats at this time point. IL-1β, IL-6 and RANTES were also reduced selectively within the orbitofrontal cortex of lithium-treated rats, whereas cytokine levels in the medial prefrontal cortex and nucleus accumbens were comparable with control subjects. These results are consistent with the hypothesis that lithium may improve impulse control deficits in clinical populations by minimising the effects of pro-inflammatory signalling on neuronal activity, particularly within the orbitofrontal cortex.

Lithium Chloride Sensitivity in Yeast and Regulation of Translation

For decades, lithium chloride (LiCl) has been used as a treatment option for those living with bipolar disorder (BD). As a result, many studies have been conducted to examine its mode of action, toxicity, and downstream cellular responses. We know that LiCl is able to affect cell signaling and signaling transduction pathways through protein kinase C and glycogen synthase kinase-3, which are considered to be important in regulating gene expression at the translational level. However, additional downstream effects require further investigation, especially in translation pathway. In yeast, LiCl treatment affects the expression, and thus the activity, of PGM2, a phosphoglucomutase involved in sugar metabolism. Inhibition of PGM2 leads to the accumulation of intermediate metabolites of galactose metabolism causing cell toxicity. However, it is not fully understood how LiCl affects gene expression in this matter. In this study, we identified three genes, NAM7, PUS2, and RPL27B, which increase yeast LiCl sensitivity when deleted. We further demonstrate that NAM7, PUS2, and RPL27B influence translation and exert their activity through the 5′-Untranslated region (5′-UTR) of PGM2 mRNA in yeast.

The Effect of Lithium on Inflammation-Associated Genes in Lipopolysaccharide-Activated Raw 264.7 Macrophages

Lithium remains the preferred Food and Drug Administration- (FDA-) approved psychiatric drug for treatment of bipolar disorders since its medical establishment more than half a century ago. Recent studies revealed a promising role for lithium in the regulation of inflammation, oxidative stress, and neurodegeneration albeit unclear about its exact mode of action. Thus, the intention of this study is to delineate the regulatory mechanisms of lithium on oxidative stress in lipopolysaccharide- (LPS-) activated macrophages by evaluating its effects on nuclear factor-κB (NF-κB) activity and mRNA expression of multiple oxidative stress-related NF-κB genes. Raw 264.7 macrophages were treated with up to 10 mM lithium, and no change in cell proliferation, viability, growth, and cell adhesion was observed in real time. Pretreatment with low doses of lithium was shown to reduce nitric oxide (NO) production in LPS-activated macrophages. A reduced internal H₂DCFDA fluorescence intensity, indicative of reduced reactive oxygen species (ROS) production, was observed in LPS-activated Raw 264.7 macrophages treated with lithium. Lithium has been shown to lower the production of the chemokine RANTES; furthermore, this inhibitory action of lithium has been suggested to be independent of glycogen synthase kinase-3 β (GSK3β) activity. It is shown here that lithium modulates the expression of several inflammatory genes including IκB-α, TRAF3, Tollip, and NF-κB1/p50 which are regulators of the NF-κB pathway. Moreover, lithium inhibits NF-κB activity by lowering nuclear translocation of NF-κB in LPS-activated macrophages. This is the first study to associate Tollip, Traf-3, and IκB-α mRNA expression with lithium effect on NF-κB activity in LPS-activated Raw 264.7 macrophages. Although these effects were obtained using extratherapeutic concentrations of lithium, results of this study provide useful information towards understanding the mode of action of lithium. This study associates lithium with reduced oxidative stress in LPS-activated Raw 264.7 macrophages and further suggests candidate molecular targets for the regulation of oxidative stress-related diseases using lithium beyond bipolar disorders.

Sensitivity of yeast to lithium chloride connects the activity of YTA6 and YPR096C to translation of structured mRNAs

Lithium Chloride (LiCl) toxicity, mode of action and cellular responses have been the subject of active investigations over the past decades. In yeast, LiCl treatment is reported to reduce the activity and alters the expression of PGM2, a gene that encodes a phosphoglucomutase involved in sugar metabolism. Reduced activity of phosphoglucomutase in the presence of galactose causes an accumulation of intermediate metabolites of galactose metabolism leading to a number of phenotypes including growth defect. In the current study, we identify two understudied yeast genes, YTA6 and YPR096C that when deleted, cell sensitivity to LiCl is increased when galactose is used as a carbon source. The 5’-UTR of PGM2 mRNA is structured. Using this region, we show that YTA6 and YPR096C influence the translation of PGM2 mRNA.

Integrative analysis of lithium treatment associated effects on brain structure and peripheral gene expression reveals novel molecular insights into mechanism of action

Lithium is a highly effective medication for bipolar disorder, but its mechanism of action remains unknown. In this study, brain MRI scans and blood samples for gene expression (total of 110 scans and 109 blood samples) were collected from 21 bipolar subjects before and after 2 and 8 weeks of lithium monotherapy and at the same time-points from untreated 16 healthy controls. We used linear mixed-effects models to identify brain structural features and genes with expression changed after lithium treatment, with correction for multiple testing, and correlated their concurrent changes to identify molecular pathways associated with lithium effects. There are significant increases in gray matter fraction, global cortical thickness, and the frontal and parietal cortices after 8 weeks of lithium treatment (corrected p < 0.05). Volume increases were also seen for putamen, hippocampus, thalamic nuclei, and thalamic substructures. Several genes showed significant expression changes, and 14 gene pathways were identified for the present integration analysis. Of these, nine pathways had significant correlations with structural changes (FDR < 0.05). Three neurotrophy-related pathways (GDNF family of ligands, NFAT immune-response, and p53-signaling pathway) correlated with structural changes in multiple regions. Mediation analysis showed that the sphingomyelin metabolism pathway is associated with HAM-D change (p < 0.01), and this effect is mediated via the volume of mediodorsal thalamus (p < 0.03). In summary, the integration of lithium effects on brain structural and peripheral gene expression changes revealed effects on several neurotrophic molecular pathways, which provides further insights into the mechanism of lithium action.

Lithium and glutamine synthetase: Protective effects following stress

Even though lithium is widely used as treatment for mood disorders, the exact mechanisms of lithium in the brain remain unknown. A potential mechanism affects the downstream target of the Wnt/β-catenin signaling pathway, specifically glutamine synthetase (GS). Here, we investigate the effect of lithium on GS-promoter activity in the brain. Over seven days, B6C3H-Glultm^(T2A-LacZ) mice that carry LacZ as a reporter gene fused to the GS-promotor received either daily intraperitoneal injections of lithium carbonate (25 mg/kg) or NaCl, or no treatment. Following histochemical staining of β-galactosidase relative GS-promotor activity was measured by analyzing the intensity of the staining. Furthermore cell counts were conducted. GS-promotor activity was significantly decreased in female compared to male mice. Treatment group differences were only found in male hippocampi, with increased activity after NaCl treatment compared to both the lithium treatment and no treatment. Lithium treatment increased the overall number of cells in the CA1 region in males. Daily injections of NaCl might have been sufficient to induce stress-related GS-promotor activity changes in male mice; however, lithium was able to reverse the effect. Taken together, the current study indicates that lithium acts to prevent stress, rather affecting general GS-promoter activity.

Acute anxiety disorder, major depressive disorder, bipolar disorder and schizophrenia are related to different patterns of nigrostriatal and mesolimbic dopamine dysfunction

Dopamine (DA) receptor and transporter dysfunctions play a major role in the pathophysiology of neuropsychiatric diseases including anxiety disorder (AD), major depressive disorder (MDD), bipolar disorder (BD) in the manic (BDman) or depressive (BDdep) state and schizophrenia (SZ). We performed a PUBMED search, which provided a total of 239 in vivo imaging studies with either positron emission tomography (PET) or single-proton emission computed tomography (SPECT). In these studies, DA transporter binding, D1 receptor (R) binding, D2R binding, DA synthesis and/or DA release in patients with the primary diagnosis of acute AD (n=310), MDD (n=754), BDman (n=15), BDdep (n=49) or SZ (n=1532) were compared to healthy individuals. A retrospective analysis revealed that AD, MDD, BDman, BDdep and SZ differed as to affected brain region(s), affected synaptic constituent(s) and extent as well as direction of dysfunction in terms of either sensitization or desensitization of transporter and/or receptor binding sites. In contrast to AD and SZ, in MDD, BDman and BDdep, neostriatal DA function was normal, whereas MDD, BDman, and BDdep were characterized by the increased availability of prefrontal and frontal DA. In contrast to AD, MDD, BDman and BDdep, DA function in SZ was impaired throughout the nigrostriatal and mesolimbocortical system with an increased availability of DA in the striatothalamocortical and a decreased availability in the mesolimbocortical pathway.

Lithium monotherapy associated longitudinal effects on resting state brain networks in clinical treatment of bipolar disorder

OBJECTIVES

Lithium is one of the most effective and specific treatments for bipolar disorder (BP), but the neural mechanisms by which lithium impacts symptoms remain unclear. Past research has been limited by a reliance on cross-sectional designs, which does not allow for identification of within-person changes due to lithium and has not examined communication between brain regions (ie, networks). In the present study, we prospectively investigated the lithium monotherapy associated effects in vivo on the brain connectome in medication-free BP patients. In particular, we examined the within-person impact of lithium treatment on connectome indices previously linked to mania and depression in bipolar disorder.

METHODS

Thirty-nine medication-free subjects - 26 BP (13 (hypo)manic and 13 depressed) and 13 closely matched healthy controls (HC) - were included. fMRI data were obtained at 3 timepoints: baseline, after 2 weeks, and after 8 weeks (total of 117 scans: 78 BP and 39 HC scans). BP subjects were clinically treated with lithium for 8 weeks while HC were scanned at the same time points but not treated. Graph theory metrics and repeated measures GLM were used to analyze lithium treatment associated effects.

RESULTS

Consistent with hypotheses, lithium treatment was associated with a normalizing effect on mania-related connectome indices. Furthermore, shifts in both mania- and depression-related connectome indices were proportional to symptom change. Finally, lithium treatment-associated impact on amygdala function differed depending on baseline mood.

CONCLUSIONS

Present findings provide deeper insight into the therapeutic neural mechanisms associated with lithium treatment.

Association of a Noncoding RNA Postmortem With Suicide by Violent Means and In Vivo With Aggressive Phenotypes

BACKGROUND

Previous findings suggest that differences in brain expression of a human-specific long intergenic noncoding RNA (LINC01268; GRCh37/hg19: LOC285758) may be linked to suicide by violent methods. We sought to replicate and extend these findings in a new sample and translate the results to the behavioral level in living healthy subjects.

METHODS

We examined RNA sequencing data in human brains to confirm the prior postmortem association of the long intergenic noncoding RNA specifically with suicide by violent means. In addition, we used a genetic variant associated with LINC01268 expression to detect association in healthy subjects with trait aggression and with in vivo prefrontal physiology related to behavioral control. Finally, we performed weighted gene coexpression network analysis and gene ontology analysis to identify biological processes associated with a LINC01268 coexpression network.

RESULTS

In the replication sample, prefrontal expression of LINC01268 was again higher in suicides by violent means (n = 65) than in both nonsuicides (n = 78; p = 1.29 × 10^-6) and suicides by nonviolent means (n = 46; p = 1.4 × 10^-6). In the living cohort, carriers of the minor allele of a single nucleotide polymorphism associated with increased LINC01268 expression in brain scored higher on a lifetime aggression questionnaire and show diminished engagement of prefrontal cortex (Brodmann area 10) when viewing angry faces during functional magnetic resonance imaging. Weighted gene coexpression network analysis highlighted the immune response.

CONCLUSIONS

These results suggest that LINC01268 influences emotional regulation, aggressive behavior, and suicide by violent means; the underlying biological dynamics may include modulation of genes potentially engaged in the immune response.

Timing of onset of lithium relapse prevention in bipolar disorder: evidence from randomised trials

Lithium is widely prescribed, but the timing of key effects remains uncertain. The timing of onset of its relapse prevention effects is clarified by placebo-controlled randomised trials (3 studies, n = 1120). Lithium reduced relapse into any mood episode over the first 2 weeks of treatment (hazard ratio 0.40, 95% CI 0.16-0.97). Fewer manic relapses were evident within the first 4 weeks, however, early effects on depressive relapse were not demonstrated. There is an early onset of lithium relapse prevention effects in bipolar disorder, particularly against manic relapse. Full effects against depressive relapse may develop over a longer period.Declaration of interestM.J.T. reports personal fees from Sunovion, Otsuka, Lundbeck, outside the submitted work.

Drosophila CaV2 channels harboring human migraine mutations cause synapse hyperexcitability that can be suppressed by inhibition of a Ca2+ store release pathway

Gain-of-function mutations in the human CaV2.1 gene CACNA1A cause familial hemiplegic migraine type 1 (FHM1). To characterize cellular problems potentially triggered by CaV2.1 gains of function, we engineered mutations encoding FHM1 amino-acid substitutions S218L (SL) and R192Q (RQ) into transgenes of Drosophila melanogaster CaV2/cacophony. We expressed the transgenes pan-neuronally. Phenotypes were mild for RQ-expressing animals. By contrast, single mutant SL- and complex allele RQ,SL-expressing animals showed overt phenotypes, including sharply decreased viability. By electrophysiology, SL- and RQ,SL-expressing neuromuscular junctions (NMJs) exhibited enhanced evoked discharges, supernumerary discharges, and an increase in the amplitudes and frequencies of spontaneous events. Some spontaneous events were gigantic (10-40 mV), multi-quantal events. Gigantic spontaneous events were eliminated by application of TTX-or by lowered or chelated Ca2+-suggesting that gigantic events were elicited by spontaneous nerve firing. A follow-up genetic approach revealed that some neuronal hyperexcitability phenotypes were reversed after knockdown or mutation of Drosophila homologs of phospholipase Cβ (PLCβ), IP3 receptor, or ryanodine receptor (RyR)-all factors known to mediate Ca2+ release from intracellular stores. Pharmacological inhibitors of intracellular Ca2+ store release produced similar effects. Interestingly, however, the decreased viability phenotype was not reversed by genetic impairment of intracellular Ca2+ release factors. On a cellular level, our data suggest inhibition of signaling that triggers intracellular Ca2+ release could counteract hyperexcitability induced by gains of CaV2.1 function.

The observed alteration in BCL2 expression following lithium treatment is influenced by the choice of normalization method

Upregulation of B-cell CLL/lymphoma (BCL)2 expression following lithium treatment is seemingly well established and has been related to the neuroprotective property of the drug. However, while demonstrated by some (but not all) studies based on low-throughput techniques (e.g. qPCR) this effect is not reflected in high-throughput studies, such as microarrays and RNAseq. This manuscript presents a systematic review of currently available reports of lithium's effect on BCL2 expression. To our surprise, we found that the majority of the literature does not support the effect of lithium on BCL2 transcript or protein levels. Moreover, among the positive reports, several used therapeutically irrelevant lithium doses while others lack statistical power. We also noticed that numerous low-throughput studies normalized the signal using genes/proteins affected by lithium, imposing possible bias. Using wet bench experiments and reanalysis of publicly available microarray data, here we show that the reference gene chosen for normalization critically impacts the outcome of qPCR analyses of lithium's effect on BCL2 expression. Our findings suggest that experimental results might be severely affected by the choice of normalizing genes, and emphasize the need to re-evaluate stability of these genes in the context of the specific experimental conditions.

DIXDC1 contributes to psychiatric susceptibility by regulating dendritic spine and glutamatergic synapse density via GSK3 and Wnt/β-catenin signaling

Mice lacking DIX domain containing-1 (DIXDC1), an intracellular Wnt/β-catenin signal pathway protein, have abnormal measures of anxiety, depression and social behavior. Pyramidal neurons in these animals' brains have reduced dendritic spines and glutamatergic synapses. Treatment with lithium or a glycogen synthase kinase-3 (GSK3) inhibitor corrects behavioral and neurodevelopmental phenotypes in these animals. Analysis of DIXDC1 in over 9000 cases of autism, bipolar disorder and schizophrenia reveals higher rates of rare inherited sequence-disrupting single-nucleotide variants (SNVs) in these individuals compared with psychiatrically unaffected controls. Many of these SNVs alter Wnt/β-catenin signaling activity of the neurally predominant DIXDC1 isoform; a subset that hyperactivate this pathway cause dominant neurodevelopmental effects. We propose that rare missense SNVs in DIXDC1 contribute to psychiatric pathogenesis by reducing spine and glutamatergic synapse density downstream of GSK3 in the Wnt/β-catenin pathway.

GSK3β inhibitor promotes myelination and mitigates muscle atrophy after peripheral nerve injury

Delay of axon regeneration after peripheral nerve injury usually leads to progressive muscle atrophy and poor functional recovery. The Wnt/β-catenin signaling pathway is considered to be one of the main molecular mechanisms that lead to skeletal muscle atrophy in the elderly. We hold the hypothesis that the innervation of target muscle can be promoted by accelerating axon regeneration and decelerating muscle cell degeneration so as to improve functional recovery of skeletal muscle following peripheral nerve injury. This process may be associated with the Wnt/β-catenin signaling pathway. Our study designed in vitro cell models to simulate myelin regeneration and muscle atrophy. We investigated the effects of SB216763, a glycogen synthase kinase 3 beta inhibitor, on the two major murine cell lines RSC96 and C2C12 derived from Schwann cells and muscle satellite cells. The results showed that SB216763 stimulated the Schwann cell migration and myotube contraction. Quantitative polymerase chain reaction results demonstrated that myelin related genes, myelin associated glycoprotein and cyclin-D1, muscle related gene myogenin and endplate-associated gene nicotinic acetylcholine receptors levels were stimulated by SB216763. Immunocytochemical staining revealed that the expressions of β-catenin in the RSC96 and C2C12 cytosolic and nuclear compartments were increased in the SB216763-treated cells. These findings confirm that the glycogen synthase kinase 3 beta inhibitor, SB216763, promoted the myelination and myotube differentiation through the Wnt/β-catenin signaling pathway and contributed to nerve remyelination and reduced denervated muscle atrophy after peripheral nerve injury.

Lithium reverses mechanical allodynia through a mu opioid-dependent mechanism

Background

Lithium is widely used to treat bipolar disorders and displays mood stabilizing properties. In addition, lithium relieves painful cluster headaches and has a strong analgesic effect in neuropathic pain rat models.

Objectives

To investigate the analgesic effect of lithium on the cuff model of neuropathic pain.

Methods

We used behavioral and pharmacological approaches to study the analgesic effect of a single injection of lithium in wild-type and mu opioid receptor (MOR) null cuffed neuropathic mice. Mass spectrometry and enzyme-linked immunosorbent assay allowed to measure the levels of endogenous MOR agonist beta-endorphin as well as monoamines in brain and plasma samples 4 h after lithium administration.

Results

A single injection of lithium chloride (100 mg/kg, ip) alleviated mechanical allodynia for 24 h, and this effect was absent in MOR null neuropathic mice. Biochemical analyses highlight a significant increase in beta-endorphin levels by 30% in the brain of lithium-treated mice compared to controls. No variation of beta-endorphin was detected in the blood.

Conclusions

Together, our results provide evidence that lithium induces a long-lasting analgesia in neuropathic mice presumably through elevated brain levels of beta-endorphin and the activation of MORs.

Different patterns of dopaminergic and serotonergic dysfunction in manic, depressive and euthymic phases of bipolar disorder

A variety of alterations in brain neurotransmitter systems has been proposed as the cause of bipolar disorder (BD). We conducted a PUBMED search, which provided a total of 45 in vivo investigations with PET and SPECT, in which binding to serotonin transporter (SERT), 5-HT1A receptor (R), 5-HT2AR, dopamine transporter (DAT), vesicular monoamine transporter (VMAT2), D1R, D2R, muscarinic M2R and nicotinic ß2-nAChR as well as dopamine synthesis and/or dopamine release were assessed in BD patients in the manic (6 studies, 39 patients, 77 controls), depressive (15 studies, 248 patients, 488 controls) or eu- thymic condition (18 studies, 265 patients, 293 controls) and in mixed collectives of BD patients (6 studies, 55 patients, 80 controls). The retrospective analysis revealed a complex pattern of dysregulations within and between neurotransmitter systems, which is causally linked to the acute and euthymic states of BD. While increased mesencephalic, limbic and parietotemporoccipital serotonin and increased frontal dopamine underlie mania, the depressive state is characterized by decreased frontal and limbic serotonin, increased frontal and limbic acetylcholine and increased frontal dopamine. Also in euthymia, no normalization of receptor and transporter densities was observed. Alterations of regulation states of bindings sites, however, act together to achieve a normalization of mesencephalic, limbic and cortical serotonin.

Phosphorylation promotes activation-induced cytidine deaminase activity at the Myc oncogene

The molecular mechanisms that regulate AID mutator activity at off-target genes are not well characterized. Mu et al. show AID phosphorylation dynamically controls activity at Myc and other sites. Pharmacological induction of AID phosphorylation leads to increased mutations, double strand breakss and translocations.

Activation-induced cytidine deaminase (AID) is a mutator enzyme that targets immunoglobulin (Ig) genes to initiate antibody somatic hypermutation (SHM) and class switch recombination (CSR). Off-target AID association also occurs, which causes oncogenic mutations and chromosome rearrangements. However, AID occupancy does not directly correlate with DNA damage, suggesting that factors beyond AID association contribute to mutation targeting. CSR and SHM are regulated by phosphorylation on AID serine38 (pS38), but the role of pS38 in off-target activity has not been evaluated. We determined that lithium, a clinically used therapeutic, induced high AID pS38 levels. Using lithium and an AID-S38 phospho mutant, we compared the role of pS38 in AID activity at the Ig switch region and off-target Myc gene. We found that deficient pS38 abated AID chromatin association and CSR but not mutation at Myc. Enhanced pS38 elevated Myc translocation and mutation frequency but not CSR or Ig switch region mutation. Thus, AID activity can be differentially targeted by phosphorylation to induce oncogenic lesions.

The complexities of lithium

This is a editorial focus written to highlight the findings by Yang et al in the article “The Soluble (Pro)Renin Receptor Does Not Influence Lithium‐Induced Diabetes Insipidus but Does Provoke Beiging of White Adipose Tissue in Mice.”

Serum phosphatidylinositol as a biomarker for bipolar disorder liability

OBJECTIVES

Individuals with bipolar disorder (BPD) exhibit alterations in their phospholipid levels. It is unclear whether these alterations are a secondary consequence of illness state, or if phospholipids and illness risk overlap genetically. If the latter were true, then phospholipids might provide key insights into the pathophysiology of the illness. Therefore, we rank-ordered phospholipid classes by their genetic overlap with BPD risk in order to establish which class might be most informative in terms of increasing our understanding of illness pathophysiology.

METHODS

Analyses were conducted in a sample of 558 individuals, unselected for BPD, from 38 extended pedigrees (average family size=14.79, range=2-82). We calculated a coefficient of relatedness for all family members of nine individuals with BPD in the sample (N=185); this coefficient was set to be zero in unrelated individuals (N=373). Then, under an endophenotype ranking value (ERV) approach, this scalar index was tested against 13 serum-based phospholipid concentrations in order to rank-order lipid classes by their respective overlap with BPD risk.

RESULTS

The phosphatidylinositol class was significantly heritable (h² =0.26, P=6.71 × 10^-05 ). It was the top-ranked class, and was significantly associated with BPD risk after correction for multiple testing (β=-1.18, P=2.10 × 10^-03 , ERV=0.49).

CONCLUSIONS

We identified a peripheral biomarker, serum-based phosphatidylinositol, which exhibits a significant association with BPD risk. Therefore, given that phosphatidylinositol and BPD risk share partially common etiology, it seems that this lipid class warrants further investigation, not only in terms of treatment, but also as a promising diagnostic and risk marker.

Lithium Accumulates in Neurogenic Brain Regions as Revealed by High Resolution Ion Imaging

Lithium (Li) is a potent mood stabilizer and displays neuroprotective and neurogenic properties. Despite extensive investigations, the mechanisms of action have not been fully elucidated, especially in the juvenile, developing brain. Here we characterized lithium distribution in the juvenile mouse brain during 28 days of continuous treatment that result in clinically relevant serum concentrations. By using Time-of-Flight Secondary Ion Mass Spectrometry- (ToF-SIMS) based imaging we were able to delineate temporospatial lithium profile throughout the brain and concurrent distribution of endogenous lipids with high chemical specificity and spatial resolution. We found that Li accumulated in neurogenic regions and investigated the effects on hippocampal neurogenesis. Lithium increased proliferation, as judged by Ki67-immunoreactivity, but did not alter the number of doublecortin-positive neuroblasts at the end of the treatment period. Moreover, ToF-SIMS revealed a steady depletion of sphingomyelin in white matter regions during 28d Li-treatment, particularly in the olfactory bulb. In contrast, cortical levels of cholesterol and choline increased over time in Li-treated mice. This is the first study describing ToF-SIMS imaging for probing the brain-wide accumulation of supplemented Li in situ. The findings demonstrate that this technique is a powerful approach for investigating the distribution and effects of neuroprotective agents in the brain.

Neurodevelopmental Perspectives on Wnt Signaling in Psychiatry

Mounting evidence indicates that Wnt signaling is relevant to pathophysiology of diverse mental illnesses including schizophrenia, bipolar disorder, and autism spectrum disorder. In the 35 years since Wnt ligands were first described, animal studies have richly explored how downstream Wnt signaling pathways affect an array of neurodevelopmental processes and how their disruption can lead to both neurological and behavioral phenotypes. Recently, human induced pluripotent stem cell (hiPSC) models have begun to contribute to this literature while pushing it in increasingly translational directions. Simultaneously, large-scale human genomic studies are providing evidence that sequence variation in Wnt signal pathway genes contributes to pathogenesis in several psychiatric disorders. This article reviews neurodevelopmental and postneurodevelopmental functions of Wnt signaling, highlighting mechanisms, whereby its disruption might contribute to psychiatric illness, and then reviews the most reliable recent genetic evidence supporting that mutations in Wnt pathway genes contribute to psychiatric illness. We are proponents of the notion that studies in animal and hiPSC models informed by the human genetic data combined with the deep knowledge base and tool kits generated over the last several decades of basic neurodevelopmental research will yield near-term tangible advances in neuropsychiatry.

From direct to indirect lithium targets: a comprehensive review of omics data

Metal ions are critical to a wide range of biological processes.

Lithium-Responsive Seizure-Like Hyperexcitability Is Caused by a Mutation in the Drosophila Voltage-Gated Sodium Channel Gene paralytic

Shudderer (Shu) is an X-linked dominant mutation in Drosophila melanogaster identified more than 40 years ago. A previous study showed that Shu caused spontaneous tremors and defects in reactive climbing behavior, and that these phenotypes were significantly suppressed when mutants were fed food containing lithium, a mood stabilizer used in the treatment of bipolar disorder (Williamson, 1982). This unique observation suggested that the Shu mutation affects genes involved in lithium-responsive neurobiological processes. In the present study, we identified Shu as a novel mutant allele of the voltage-gated sodium (Na_v) channel gene paralytic (para). Given that hypomorphic para alleles and RNA interference-mediated para knockdown reduced the severity of Shu phenotypes, Shu was classified as a para hypermorphic allele. We also demonstrated that lithium could improve the behavioral abnormalities displayed by other Na_v mutants, including a fly model of the human generalized epilepsy with febrile seizures plus. Our electrophysiological analysis of Shu showed that lithium treatment did not acutely suppress Na_v channel activity, indicating that the rescue effect of lithium resulted from chronic physiological adjustments to this drug. Microarray analysis revealed that lithium significantly alters the expression of various genes in Shu, including those involved in innate immune responses, amino acid metabolism, and oxidation-reduction processes, raising the interesting possibility that lithium-induced modulation of these biological pathways may contribute to such adjustments. Overall, our findings demonstrate that Na_v channel mutants in Drosophila are valuable genetic tools for elucidating the effects of lithium on the nervous system in the context of neurophysiology and behavior.

Neuronal NOS Induces Neuronal Differentiation Through a PKCα-Dependent GSK3β Inactivation Pathway in Hippocampal Neural Progenitor Cells

We investigated the role of neuronal nitric oxide synthase (nNOS) in the neuronal differentiation of neural progenitor cells (NPCs) from hippocampi of E16.5 rat embryos. The production of nitric oxide (NO) and nNOS expression increased markedly during neuronal differentiation as did the expression of neurotrophin-3 (NT3), neurotrophin-4/5 (NT 4/5), and synapsin I. nNOS siRNA or the nNOS inhibitor, 7-nitroindazole (7-NI), decreased expression of the neurotrophins and synapsin I, and suppressed neurite outgrowth. These results suggest that nNOS plays a critical role in neuronal differentiation of hippocampal NPCs. nNOS-mediated neuronal differentiation is controlled by calcineurin since cyclosporin A (CsA), a calcineurin inhibitor, decreased nNOS activation and NO production, and inhibited neurite outgrowth. We found that inactivation of glycogen synthase kinase-3 beta (GSK3β) resulting from activation of protein kinase C alpha (PKCα) is involved in the nNOS-mediated neuronal differentiation. Moreover, lithium chloride (LiCl), a GSK3β inhibitor, increased neuronal differentiation by inhibiting the proliferation of NPCs. Taken together, these results suggest that neuronal differentiation is dependent on calcineurin-mediated activation of nNOS; this induces PKCα-dependent inactivation of GSK3β, which leads to inhibition of the proliferation of hippocampal NPCs.

Lithium-responsive genes and gene networks in bipolar disorder patient-derived lymphoblastoid cell lines

Lithium (Li) is the mainstay mood stabilizer for the treatment of bipolar disorder (BD), although its mode of action is not yet fully understood nor is it effective in every patient. We sought to elucidate the mechanism of action of Li and to identify surrogate outcome markers that can be used to better understand its therapeutic effects in BD patients classified as good (responders) and poor responders (nonresponders) to Li treatment. To accomplish these goals, RNA-sequencing gene expression profiles of lymphoblastoid cell lines (LCLs) were compared between BD Li responders and nonresponders with healthy controls before and after treatment. Several Li-responsive gene coexpression networks were discovered indicating widespread effects of Li on diverse cellular signaling systems including apoptosis and defense response pathways, protein processing and response to endoplasmic reticulum stress. Individual gene markers were also identified, differing in response to Li between BD responders and nonresponders, involved in processes of cell cycle and nucleotide excision repair that may explain part of the heterogeneity in clinical response to treatment. Results further indicated a Li gene expression signature similar to that observed with clonidine treatment, an α2-adrenoceptor agonist. These findings provide a detailed mechanism of Li in LCLs and highlight putative surrogate outcome markers that may permit for advanced treatment decisions to be made and for facilitating recovery in BD patients.

Early postnatal exposure to lithium in vitro induces changes in AMPAR mEPSCs and vesicular recycling at hippocampal glutamatergic synapses

Lithium is an effective mood stabilizer but its use is associated with many side effects. Electrophysiological recordings of miniature excitatory postsynaptic currents (mEPSCs) mediated by glutamate receptor AMPA-subtype (AMPARs) in hippocampal pyramidal neurons revealed that CLi (therapeutic concentration of 1 mM lithium, from days in vitro 4-10) decreased the mean amplitude and mean rectification index (RI) of AMPAR mEPSCs. Lowered mean RI indicate that contribution of Ca2+ -permeable AMPARs in synaptic events is higher in CLi neurons (supported by experiments sensitive to Ca2+ -permeable AMPAR modulation). Co-inhibiting PKA, GSK-3 beta and glutamate reuptake was necessary to bring about changes in AMPAR mEPSCs similar to that seen in CLi neurons. FM1-43 experiments revealed that recycling pool size was affected in CLi cultures. Results from minimum loading, chlorpromazine treatment and hyperosmotic treatment experiments indicate that endocytosis in CLi is affected while not much difference is seen in modes of exocytosis. CLi cultures did not show the high KCl associated presynaptic potentiation observed in control cultures. This study, by calling attention to long-term lithium-exposure-induced synaptic changes, might have implications in understanding the side effects such as CNS complications occurring in perinatally exposed babies and cognitive dulling seen in patients on lithium treatment.

Unidirectional Flux Balance of Monovalent Ions in Cells with Na/Na and Li/Na Exchange: Experimental and Computational Studies on Lymphoid U937 Cells

Monovalent ion traffic across the cell membrane occurs via various pathways. Evaluation of individual fluxes in whole cell is hampered by their strong interdependence. This difficulty can be overcome by computational analysis of the whole cell flux balance. However, the previous computational studies disregarded ion movement of the self-exchange type. We have taken this exchange into account. The developed software allows determination of unidirectional fluxes of all monovalent ions via the major pathways both under the balanced state and during transient processes. We show how the problem of finding the rate coefficients can be solved by measurement of monovalent ion concentrations and some of the fluxes. Interdependence of fluxes due to the mandatory conditions of electroneutrality and osmotic balance and due to specific effects can be discriminated, enabling one to identify specific changes in ion transfer machinery under varied conditions. To test the effectiveness of the developed approach we made use of the fact that Li/Na exchange is known to be an analogue of the coupled Na/Na exchange. Thus, we compared the predicted and experimental data obtained on U937 cells under varied Li+ concentrations and following inhibition of the sodium pump with ouabain. We found that the coupled Na/Na exchange in U937 cells comprises a significant portion of the entire Na+ turnover. The data showed that the loading of the sodium pump by Li/Na exchange involved in the secondary active Li+ transport at 1-10 mM external Li+ is small. This result may be extrapolated to similar Li+ and Na+ flux relationships in erythrocytes and other cells in patients treated with Li+ in therapeutic doses. The developed computational approach is applicable for studying various cells and can be useful in education for demonstrating the effects of individual transporters and channels on ion gradients, cell water content and membrane potential.

Lithium for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary anti-psychotic drug treatment. In these cases, various add-on medications are used, among them lithium.

OBJECTIVES

To assess whether:1. Lithium alone is an effective treatment for schizophrenia, schizophrenia-like psychoses and schizoaffective psychoses; and2. Lithium augmentation of antipsychotic medication is an effective treatment for the same illnesses.

SEARCH METHODS

In July 2012, we searched the Cochrane Schizophrenia Group's Study-Based Register of Trials which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO, and registries of clinical trials. This search was updated on January 20, 2015. For the first version of the review, we also contacted pharmaceutical companies and authors of relevant studies to identify further trials and obtain original participant data.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of lithium compared with antipsychotics or placebo (or no intervention), whether as sole treatment or as an adjunct to antipsychotic medication, in the treatment of schizophrenia or schizophrenia-like psychoses or both.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data, we calculated random-effects meta-analyses, risk ratios (RRs), and 95% confidence intervals (CI) on an intention-to-treat basis. For continuous data, we calculated mean differences (MD) and 95% confidence intervals. We used Grading of Recommendations Assessment, Development and Evaluation (GRADE) to create 'Summary of findings' tables and assessed risk of bias for included studies.

MAIN RESULTS

The update search in 2012 detected two further studies that met our inclusion criteria. We did not find any further studies that met our inclusion criteria in the 2015 search. This review now includes 22 studies, with a total of 763 participants (median mean age: 35 years, range: 26 to 72 years). Most studies were small, of short duration, and incompletely reported. As we detected a high risk of bias in many studies, the overall methodological quality of the included sample was rather low.Three small studies comparing lithium with placebo as the sole treatment showed no difference in any of the outcomes we analysed.In eight studies comparing lithium with antipsychotic drugs as the sole treatment, more participants in the lithium group left the studies early (eight RCTs; n = 270, RR 1.77, 95% CI 1.01 to 3.11, low quality evidence).Thirteen studies examined whether the augmentation of antipsychotic drugs with lithium salts is more effective than antipsychotic drugs alone. More participants who received lithium augmentation had a clinically significant response (10 RCTs; n = 396, RR 1.81, 95% CI 1.10 to 2.97, low quality evidence). However, this effect became non-significant when we excluded participants with schizoaffective disorders in a sensitivity analysis (seven RCTs; n = 272, RR 1.64, 95% CI 0.95 to 2.81), when we excluded non-double-blind studies (seven RCTs; n = 224, RR 1.82, 95% CI 0.84 to 3.96), or when we excluded studies with high attrition (nine RCTs; n = 355, RR 1.67, CI 0.93 to 3.00). The overall acceptability of treatment (measured by the number of participants leaving the studies early) was not significantly different between groups (11 RCTs; n = 320, RR 1.89, CI 0.93 to 3.84, very low quality evidence). Few studies reported on side effects. There were no significant differences, but the database is too limited to make any judgement in this regard. For example, there were no data on thyroid dysfunction and kidney problems - two major and well-known side effects of lithium.

AUTHORS' CONCLUSIONS

The evidence base for the use of lithium in schizophrenia is limited to 22 studies of overall low methodological quality. There is no randomised trial-based evidence that lithium on its own is an effective treatment for people with schizophrenia. There is some GRADE low quality evidence that augmentation of antipsychotics with lithium is effective, but the effects are not significant when more prone-to-bias open RCTs are excluded. Nevertheless, further large and well-designed trials are justified. These should concentrate on two target groups: (1) people with no affective symptoms, so that trialists can determine whether lithium has an effect on the core symptoms of schizophrenia, and (2) people with schizoaffective disorders for whom lithium is widely used in clinical practice, although there is no evidence to support this use.

X MARCKS the spot: myristoylated alanine-rich C kinase substrate in neuronal function and disease

Intracellular protein-protein interactions are dynamic events requiring tightly regulated spatial and temporal checkpoints. But how are these spatial and temporal cues integrated to produce highly specific molecular response patterns? A helpful analogy to this process is that of a cellular map, one based on the fleeting localization and activity of various coordinating proteins that direct a wide array of interactions between key molecules. One such protein, myristoylated alanine-rich C-kinase substrate (MARCKS) has recently emerged as an important component of this cellular map, governing a wide variety of protein interactions in every cell type within the brain. In addition to its well-documented interactions with the actin cytoskeleton, MARCKS has been found to interact with a number of other proteins involved in processes ranging from intracellular signaling to process outgrowth. Here, we will explore these diverse interactions and their role in an array of brain-specific functions that have important implications for many neurological conditions.

Lithium in the treatment of bipolar disorder: pharmacology and pharmacogenetics

After decades of research, the mechanism of action of lithium in preventing recurrences of bipolar disorder remains only partially understood. Lithium research is complicated by the absence of suitable animal models of bipolar disorder and by having to rely on in vitro studies of peripheral tissues. A number of distinct hypotheses emerged over the years, but none has been conclusively supported or rejected. The common theme emerging from pharmacological and genetic studies is that lithium affects multiple steps in cellular signaling, usually enhancing basal and inhibiting stimulated activities. Some of the key nodes of these regulatory networks include GSK3 (glycogen synthase kinase 3), CREB (cAMP response element-binding protein) and Na(+)-K(+) ATPase. Genetic and pharmacogenetic studies are starting to generate promising findings, but remain limited by small sample sizes. As full responders to lithium seem to represent a unique clinical population, there is inherent value and need for studies of lithium responders. Such studies will be an opportunity to uncover specific effects of lithium in those individuals who clearly benefit from the treatment.

Molecular effects of lithium are partially mimicked by inositol-monophosphatase (IMPA)1 knockout mice in a brain region-dependent manner

We have previously shown that homozygote knockout (KO) of inositol-monophosphatase1 (IMPA1) results in lithium (Li)-like behavior. We now aimed to find out whether Li-treated mice and IMPA1 KO mice exhibit neurochemical similarity at the gene- and protein-expression level. Hippocampal and frontal cortex B-cell lymphoma (Bcl-2), Bcl-2-associated X protein (BAX), P53, Perodoxin2 (PRDX2), myristoylated alanine-rich C kinase substrate (MARCKS) and neuropeptide Y (NPY) mRNA levels, and hippocampal, frontal cortex and hypothalamic cytokine levels, all previously reported to be affected by lithium treatment, were measured in three groups of mice: wildtype (WT) on regular-food (RF), WT on Li-supplemented food (Li-treated) and IMPA1-KOs. Hippocampal and frontal cortex Bcl-2 and MARCKS were the only genes commonly affected (downregulated) by Li and IMPA1 KO; Bcl-2 - by 28% and 19%, respectively; MARCKS - by about 20% in both regions. The effect of Li and of IMPA1 KO on cytokine levels differed among the three brain areas studied. Only in the hippocampus both interventions exerted similar effects. Frontal cortex cytokine levels were unaffected neither by Li nor by IMPA1 KO. Similar changes in Bcl-2 and MARCKS but not in PRDX2 and NPY following both Li-treatment and IMPA1 KO suggest a mechanism different than inositol-monophosphatase1 inhibition for Li׳s effect on the latter genes. The cytokine levels results suggest that the mechanism mediating Li׳s effect on the inflammatory system differs among brain regions. Only in the hippocampus the results favor the involvement of the phosphatidylinositol (PI) cycle.

Protein kinase C inhibition rescues manic-like behaviors and hippocampal cell proliferation deficits in the sleep deprivation model of mania

BACKGROUND

Recent studies revealed that bipolar disorder may be associated with deficits of neuroplasticity. Additionally, accumulating evidence has implicated alterations of the intracellular signaling molecule protein kinase C (PKC) in mania.

METHODS

Using sleep deprivation (SD) as an animal model of mania, this study aimed to examine the possible relationship between PKC and neuroplasticity in mania. Rats were subjected to SD for 72 h and tested behaviorally. In parallel, SD-induced changes in hippocampal cell proliferation were evaluated with bromodeoxyuridine (BrdU) labeling. We then examined the effects of the mood stabilizer lithium, the antipsychotic agent aripiprazole, and the PKC inhibitors chelerythrine and tamoxifen on both behavioral and cell proliferation impairments induced by SD. The antidepressant fluoxetine was used as a negative control.

RESULTS

We found that SD triggered the manic-like behaviors such as hyperlocomotion and increased sleep latency, and reduced hippocampal cell proliferation. These alterations were counteracted by an acute administration of lithium and aripiprazole but not of fluoxetine, and only a single administration of aripiprazole increased cell proliferation on its own. Importantly, SD rats exhibited increased levels of phosphorylated synaptosomal-associated protein 25 (SNAP-25) in the hippocampus and prefrontal cortex, suggesting PKC overactivity. Moreover, PKC inhibitors attenuated manic-like behaviors and rescued cell proliferation deficits induced by SD.

CONCLUSIONS

Our findings confirm the relevance of SD as a model of mania, and provide evidence that antimanic agents are also able to prevent SD-induced decrease of hippocampal cell proliferation. Furthermore, they emphasize the therapeutic potential of PKC inhibitors, as revealed by their antimanic-like and pro-proliferative properties.

Histone deacetylase inhibitors reverse manic-like behaviors and protect the rat brain from energetic metabolic alterations induced by ouabain

Studies have revealed alterations in mitochondrial complexes in the brains of bipolar patients. However, few studies have examined changes in the enzymes of the tricarboxylic acid cycle. Several preclinical studies have suggested that histone deacetylase inhibitors may have antimanic effects. The present study aims to investigate the effects of lithium, valproate and sodium butyrate, a histone deacetylase inhibitor, on the activity of tricarboxylic acid cycle enzymes in the brains of rats subjected to an animal model of mania induced by ouabain. Wistar rats received a single intracerebroventricular injection of ouabain or cerebrospinal fluid. Starting on the day following the intracerebroventricular injection, the rats were treated for 7days with intraperitoneal injections of saline, lithium, valproate or sodium butyrate. Risk-taking behavior, locomotor and exploratory activities were measured using the open-field test. Citrate synthase, succinate dehydrogenase, and malate dehydrogenase were examined in the frontal cortex and hippocampus. All treatments reversed ouabain-related risk-taking behavior and hyperactivity in the open-field test. Ouabain inhibited tricarboxylic acid cycle enzymes in the brain, and valproate and sodium butyrate but not lithium reversed this ouabain-induced dysfunction. Thus, protecting the tricarboxylic acid cycle may contribute to the therapeutic effects of histone deacetylase inhibitors.

Effects of lithium and valproic acid on BDNF protein and gene expression in an in vitro human neuron-like model of degeneration

One of the common effects of lithium (Li) and valproic acid (VPA) is their ability to protect against excitotoxic insults. Neurodegenerative and neuropsychiatric diseases may be also associated with altered trophic support of brain-derived neurotrophic factor (BDNF), the most widely distributed neurotrophin in the central nervous system. However, despite these evidences, the effect of Li-VPA combination on BDNF after excitoxic insult has been inadequately investigated. We address this issue by exposing a human neuroblastoma cell line (SH-SY5Y) to neurotoxic concentration of L-glutamate and exploring whether the neuroprotective action of Li-VPA on these cells is associated with changes in BDNF protein and mRNA levels. The results showed that pre-incubation of Li-VPA abolished the toxic effect of glutamate on SH-SY5Y cell survival and this neuroprotective effect was associated with increased synthesis and mRNA expression of BDNF after 24 and 48 h of incubation. In conclusion, this study demonstrates that the neuroprotective effects of Li-VPA against glutamate-induced neurotoxicity in SH-SY5Y neuroblastoma cells is associated with increased synthesis and mRNA expression of BDNF. These data further support the idea that these two drugs can be used for prevention and/or treatment of glutamate-related neurodegenerative disorders.