In search of the Holy Grail for the treatment of neurodegenerative disorders: has a simple cation been overlooked?

The autism-associated loss of δ-catenin functions disrupts social behavior

δ-catenin is expressed in excitatory synapses and functions as an anchor for the glutamatergic AMPA receptor (AMPAR) GluA2 subunit in the postsynaptic density. The glycine 34 to serine (G34S) mutation in the δ-catenin gene has been found in autism spectrum disorder (ASD) patients and results in loss of δ-catenin functions at excitatory synapses, which is presumed to underlie ASD pathogenesis in humans. However, how the G34S mutation causes loss of δ-catenin functions to induce ASD remains unclear. Here, using neuroblastoma cells, we identify that the G34S mutation increases glycogen synthase kinase 3β (GSK3β)-dependent δ-catenin degradation to reduce δ-catenin levels, which likely contributes to the loss of δ-catenin functions. Synaptic δ-catenin and GluA2 levels in the cortex are significantly decreased in mice harboring the δ-catenin G34S mutation. The G34S mutation increases glutamatergic activity in cortical excitatory neurons while it is decreased in inhibitory interneurons, indicating changes in cellular excitation and inhibition. δ-catenin G34S mutant mice also exhibit social dysfunction, a common feature of ASD. Most importantly, pharmacological inhibition of GSK3β activity reverses the G34S-induced loss of δ-catenin function effects in cells and mice. Finally, using δ-catenin knockout mice, we confirm that δ-catenin is required for GSK3β inhibition-induced restoration of normal social behavior in δ-catenin G34S mutant animals. Taken together, we reveal that the loss of δ-catenin functions arising from the ASD-associated G34S mutation induces social dysfunction via alterations in glutamatergic activity and that GSK3β inhibition can reverse δ-catenin G34S-induced synaptic and behavioral deficits.

Course of intellectual functioning in schizophrenia and bipolar disorder: a 10-year follow-up study

BACKGROUND

Intellectual functioning (IQ) is lower in schizophrenia patients compared to healthy controls, with bipolar patients intermediate between the two. Declines in IQ mark the onset of schizophrenia, while stability is generally found post-onset. There are to date few studies on long-term IQ development in bipolar disorder. This study presents 10-year follow-up data on IQ, including premorbid IQ estimates, to track the developmental course from pre-onset levels to long-term outcomes in both patient groups compared to healthy controls.

METHODS

We included 139 participants with schizophrenia, 76 with bipolar disorder and 125 healthy controls. Mixed model analyses were used to estimate developmental slopes for IQ scores from estimated premorbid level (NART IQ) through baseline (WASI IQ) measured within 12 months post-onset, to 10-year follow-up (WASI IQ), with pairwise group comparisons. The best fit was found using a model with a breakpoint at baseline assessment.

RESULTS

Only the schizophrenia group had significant declines from estimated premorbid to baseline IQ levels compared to controls. When comparing patient groups, schizophrenia patients had steeper declines than the bipolar group. Increases in IQ were found in all groups over the follow-up period.

CONCLUSIONS

Trajectories of IQ from premorbid level to 10-year follow-up indicated declines from estimated premorbid level to illness onset in both patient groups, followed by increases during the follow-up period. Schizophrenia patients had a steeper decline than bipolar patients. During follow-up, increases indicate developmental improvement for both patient groups, but with a maintained lag compared to healthy controls due to lower premorbid levels.

The autism-associated loss of δ-catenin functions disrupts social behaviors

δ-catenin is expressed in excitatory synapses and functions as an anchor for the glutamatergic AMPA receptor (AMPAR) GluA2 subunit in the postsynaptic density. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism spectrum disorder (ASD) patients and induces loss of δ-catenin functions at excitatory synapses, which is presumed to underlie ASD pathogenesis in humans. However, how the G34S mutation causes loss of δ-catenin functions to induce ASD remains unclear. Here, using neuroblastoma cells, we discover that the G34S mutation generates an additional phosphorylation site for glycogen synthase kinase 3β (GSK3β). This promotes δ-catenin degradation and causes the reduction of δ-catenin levels, which likely contributes to the loss of δ-catenin functions. Synaptic δ-catenin and GluA2 levels in the cortex are significantly decreased in mice harboring the δ-catenin G34S mutation. The G34S mutation increases glutamatergic activity in cortical excitatory neurons while it is decreased in inhibitory interneurons, indicating changes in cellular excitation and inhibition. δ-catenin G34S mutant mice also exhibit social dysfunction, a common feature of ASD. Most importantly, inhibition of GSK3β activity reverses the G34S-induced loss of δ-catenin function effects in cells and mice. Finally, using δ-catenin knockout mice, we confirm that δ-catenin is required for GSK3β inhibition-induced restoration of normal social behaviors in δ-catenin G34S mutant animals. Taken together, we reveal that the loss of δ-catenin functions arising from the ASD-associated G34S mutation induces social dysfunction via alterations in glutamatergic activity and that GSK3β inhibition can reverse δ-catenin G34S-induced synaptic and behavioral deficits.

Significance Statement

δ-catenin is important for the localization and function of glutamatergic AMPA receptors at synapses in many brain regions. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism patients and results in the loss of δ-catenin functions. δ-catenin expression is also closely linked to other autism-risk genes involved in synaptic structure and function, further implying that it is important for the autism pathophysiology. Importantly, social dysfunction is a key characteristic of autism. Nonetheless, the links between δ-catenin functions and social behaviors are largely unknown. The significance of the current research is thus predicated on filling this gap by discovering the molecular, cellular, and synaptic underpinnings of the role of δ-catenin in social behaviors.

Pharmacological Management of Anxiety Disorders in the Elderly

Anxiety disorders are common in the elderly. Additionally, anxiety symptoms often accompany co-morbid psychiatric, medical, as well as neurodegenerative diseases in the older population. Anxiety in the elderly, often accompanied by depression, can lead to worsening physical, cognitive and functional impairments in this vulnerable population. Antidepressants are considered first line treatment. Both SSRIs and SNRIs are efficacious and well-tolerated in the elderly. Some SSRIs are strong inhibitors of the cytochrome P450 hepatic pathway whereas others have less potential for drug interaction. Those antidepressants with more favorable pharmacokinetic profiles should be considered first-line in the treatment of anxiety. Mirtazapine and vortioxetine are also considered safe treatment options. Buspirone may have benefit, but lacks studies in elderly populations. Although tricyclic/tetracyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) may be effective in the elderly, their side effect and safety profiles are suboptimal and thus are not recommended in late-life. Benzodiazepines and beta blockers should generally be avoided when treating anxiety in the elderly. There is not enough evidence to support the use of antipsychotics or mood stabilizers given their risk of problems in both the long and short term. In addition, antipsychotics have a black box warning for increased mortality in elderly patients with dementia.

Lithium increases synaptic GluA2 in hippocampal neurons by elevating the δ-catenin protein

Lithium (Li⁺) is a drug widely employed for treating bipolar disorder, however the mechanism of action is not known. Here we study the effects of Li⁺ in cultured hippocampal neurons on a synaptic complex consisting of δ-catenin, a protein associated with cadherins whose mutation is linked to autism, and GRIP, an AMPA receptor (AMPAR) scaffolding protein, and the AMPAR subunit, GluA2. We show that Li⁺ elevates the level of δ-catenin in cultured neurons. δ-catenin binds to the ABP and GRIP proteins, which are synaptic scaffolds for GluA2. We show that Li⁺ increases the levels of GRIP and GluA2, consistent with Li⁺-induced elevation of δ-catenin. Using GluA2 mutants, we show that the increase in surface level of GluA2 requires GluA2 interaction with GRIP. The amplitude but not the frequency of mEPSCs was also increased by Li⁺ in cultured hippocampal neurons, confirming a functional effect and consistent with AMPAR stabilization at synapses. Furthermore, animals fed with Li⁺ show elevated synaptic levels of δ-catenin, GRIP, and GluA2 in the hippocampus, also consistent with the findings in cultured neurons. This work supports a model in which Li⁺ stabilizes δ-catenin, thus elevating a complex consisting of δ-catenin, GRIP and AMPARs in synapses of hippocampal neurons. Thus, the work suggests a mechanism by which Li⁺ can alter brain synaptic function that may be relevant to its pharmacologic action in treatment of neurological disease.

Natural and synthetic bioactive inhibitors of glycogen synthase kinase

Glycogen synthase kinase-3 is a multi-functional serine-threonine kinase and is involved in diverse physiological processes, including metabolism, cell cycle, and gene expression by regulating a wide variety of known substrates like glycogen synthase, tau-protein and β-catenin. Aberrant GSK-3 has been involved in diabetes, inflammation, cancer, Alzheimer's and bipolar disorder. In this review, we present an overview of the involvement of GSK-3 in various signalling pathways, resulting in a number of adverse pathologies due to its dysregulation. In addition, a detailed description of the small molecule inhibitors of GSK-3 with different mode of action discovered or specifically developed for GSK-3 has been presented. Furthermore, some clues for the future optimization of these promising molecules to develop specific drugs inhibiting GSK-3, for the treatment of associated disease conditions have also been discussed.

A new look at an old drug: neuroprotective effects and therapeutic potentials of lithium salts

Increasing evidence highlights bipolar disorder as being associated with impaired neurogenesis, cellular plasticity, and resiliency, as well as with cell atrophy or loss in specific brain regions. This has led most recent research to focus on the possible neuroprotective effects of medications, and particularly interesting findings have emerged for lithium. A growing body of evidence from preclinical in vitro and in vivo studies has in fact documented its neuroprotective effects from different insults acting on cellular signaling pathways, both preventing apoptosis and increasing neurotrophins and cell-survival molecules. Furthermore, positive effects of lithium on neurogenesis, brain remodeling, angiogenesis, mesenchymal stem cells functioning, and inflammation have been revealed, with a key role played through the inhibition of the glycogen synthase kinase-3, a serine/threonine kinase implicated in the pathogenesis of many neuropsychiatric disorders. These recent evidences suggest the potential utility of lithium in the treatment of neurodegenerative diseases, neurodevelopmental disorders, and hypoxic-ischemic/traumatic brain injury, with positive results at even lower lithium doses than those traditionally considered to be antimanic. The aim of this review is to briefly summarize the potential benefits of lithium salts on neuroprotection and neuroregeneration, emphasizing preclinical and clinical evidence suggesting new therapeutic potentials of this drug beyond its mood stabilizing properties.

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.

F-dynamics: automated quantification of dendrite filopodia dynamics in living neurons

BACKGROUND

Dendritic filopodia are highly motile and flexible protrusions that explore the surroundings in search for an appropriate presynaptic partner. Dendritic filopodia morphologically and functionally transform into postsynaptic dendritic spines, once the appropriate partner has been chosen. Therefore, proper formation of synapses depends on the dynamics of dendritic filopodia and spines. Thus, a rigorous assessment of dendrite filopodia behavior could be informative in providing a link between filopodia dynamics and synaptic development.

NEW METHOD

In this paper, a tool for automated tracking of filopodia dynamics, the Filopodia-dynamics program (F-dynamics), will be described, tested and applied. The aim of this study is to validate the accuracy and reliability of F-dynamics and to test the program in live neurons.

RESULTS

We demonstrate that filopodia dynamics can be reliably and accurately quantified using the F-dynamics program. In the present study, this program was used to successfully show that lithium treatment increases filopodia motility.

COMPARISON WITH EXCITING METHODS

F-dynamics is the first analysis program that is able to determine dendritic filopodia dynamics automatically across both the longitudinal and lateral dimensions.

CONCLUSION

Our data suggests that this analysis method can be used to differentiate between different experimental conditions and illustrates the potential of the program to measure pharmaceutical or genetic effects on filopodia dynamics.

Longitudinal course of cognitive deficits in bipolar disorder: a meta-analytic study

OBJECTIVE

Persistent cognitive deficits in bipolar disorder represent a major impediment to functional adjustment, but their static or progressive nature remains to be ascertained. The aim of this study was to synthesize findings from longitudinal research in order to examine the trajectory of cognitive impairment in bipolar disorder.

METHOD

A literature search was conducted through online databases covering the period between January 1990 and February 2014. Two approaches were undertaken. First, the results of longitudinal studies including neuropsychological assessment of stable bipolar patients at baseline and after a follow-up period of at least one year were meta-analyzed so as to obtain overall test-retest effect sizes for neurocognitive domains. Second, meta-analysis was restricted to longitudinal studies of bipolar patients including a control group. Patients' and controls' overall test-retest effect sizes were compared.

RESULTS

Bipolar patients' performance on 14 cognitive measures remained stable after a mean follow-up period of 4.62 years. When meta-analysis was restricted to controlled studies, no patient-control differences were found regarding longitudinal cognitive outcomes.

LIMITATIONS

Test-retest differences for medication variables and mood state could not be controlled. Sufficient data were not available to investigate a wider array of neuropsychological domains. Furthermore, most primary studies included relatively short test-restest intervals.

CONCLUSION

To date, the available evidence from longitudinal studies is not in accordance with the hypothesis of a progressive nature of cognitive deficits in BD. The implications of this finding for further research are discussed.

Wnt and lithium: a common destiny in the therapy of nervous system pathologies?

Wnt signaling is required for neurogenesis, the fate of neural progenitors, the formation of neuronal circuits during development, neuron positioning and polarization, axon and dendrite development and finally for synaptogenesis. This signaling pathway is also implicated in the generation and differentiation of glial cells. In this review, we describe the mechanisms of action of Wnt signaling pathways and their implication in the development and correct functioning of the nervous system. We also illustrate how a dysregulated Wnt pathway could lead to psychiatric, neurodegenerative and demyelinating pathologies. Lithium, used for the treatment of bipolar disease, inhibits GSK3β, a central enzyme of the Wnt/β-catenin pathway. Thus, lithium could, to some extent, mimic Wnt pathway. We highlight the possible dialogue between lithium therapy and modulation of Wnt pathway in the treatment of the diseases of the nervous system.

Cognitive function in adulthood and elderly euthymic bipolar patients: a comparison to test models of cognitive evolution

OBJECTIVE

Neurocognitive dysfunction is considered as the main predictor of overall outcome of BD. The issue of whether neurocognitive dysfunction in BD is progressive-or not-has become critical in the effort to define staging models for these disorders. Data about cognitive dysfunction evolution are scarce and contradictory. While some studies showed a progressive pattern others have found a stable form of evolution.

METHODS

Twenty four patients with BD aged 60 years or older (E-BD), 24 patients with BD aged 40 years or younger (Y-BD) and 20 healthy controls matched by the E-BD group were evaluated with traditional clinical instruments and an extensive neuropsychological battery was completed. We used ANOVA and Chi-squared for comparisons. Raw score of neurocognitive tasks was transformed to standardized Z-score from the normative data of each test to avoid the effect of age. In order to decrease the risk of type I errors, one-way multivariate analysis of variance was conducted.

RESULTS

Despite having an illness duration that was 4 times longer, E-BD did not differ in terms of key cognitive domains compared to Y-BD. These data do not support the hypothesis of a progression of cognitive dysfunction due to illness chronicity.

A quantitative review of neurocognition in euthymic late-life bipolar disorder

OBJECTIVES

A sizeable body of work has consistently documented that a number of euthymic mixed-age bipolar disorder subjects exhibit prominent impairments in a variety of cognitive domains. By contrast, knowledge about neuropsychological functioning in elderly patients is scant, despite being necessary for the adequate treatment of this population and the understanding of illness evolution. The aim of this study was to combine findings from the available literature in order to examine the pattern and extent of cognitive deficits in euthymic late-life bipolar disorder subjects.

METHODS

A literature search was conducted through the online databases PubMed, ScienceDirect, EBSCO, and Wiley-Blackwell, covering the period between January 1990 and April 2012. Effect sizes reflecting patient-control differences for 10 cognitive variables were extracted from selected investigations and combined by means of meta-analytical procedures.

RESULTS

No significant patient-control differences were found for global cognitive status as assessed with the Mini-Mental State Examination and the Clock Drawing Test. Significant overall effect sizes (Hedges' g) of between 0.61 and 0.88 were noted for sustained attention, digit span (forwards and backwards), delayed recall, serial learning, cognitive flexibility, and verbal fluency (phonemic and categorical).

CONCLUSIONS

The extent of cognitive dysfunction in euthymic late-life bipolar disorder subjects may be, on average, similar to that reported for remitted young adult patients. Larger effect sizes of impairment may be associated with late illness onset. Implications and future directions for research are proposed.

Endogenous GSK-3/shaggy regulates bidirectional axonal transport of the amyloid precursor protein

Neurons rely on microtubule (MT) motor proteins such as kinesin-1 and dynein to transport essential cargos between the cell body and axon terminus. Defective axonal transport causes abnormal axonal cargo accumulations and is connected to neurodegenerative diseases, including Alzheimer's disease (AD). Glycogen synthase kinase 3 (GSK-3) has been proposed to be a central player in AD and to regulate axonal transport by the MT motor protein kinesin-1. Using genetic, biochemical and biophysical approaches in Drosophila melanogaster, we find that endogenous GSK-3 is a required negative regulator of both kinesin-1-mediated and dynein-mediated axonal transport of the amyloid precursor protein (APP), a key contributor to AD pathology. GSK-3 also regulates transport of an unrelated cargo, embryonic lipid droplets. By measuring the forces motors generate in vivo, we find that GSK-3 regulates transport by altering the activity of kinesin-1 motors but not their binding to the cargo. These findings reveal a new relationship between GSK-3 and APP, and demonstrate that endogenous GSK-3 is an essential in vivo regulator of bidirectional APP transport in axons and lipid droplets in embryos. Furthermore, they point to a new regulatory mechanism in which GSK-3 controls the number of active motors that are moving a cargo.

Impaired inter-hemispheric integration in bipolar disorder revealed with brain network analyses

BACKGROUND

This represents the first graph theory-based brain network analysis study in bipolar disorder, a chronic and disabling psychiatric disorder characterized by severe mood swings. Many imaging studies have investigated white matter in bipolar disorder, with results suggesting abnormal white matter structural integrity, particularly in the fronto-limbic and callosal systems. However, many inconsistencies remain in the literature, and no study to date has conducted brain network analyses with a graph-theoretic approach.

METHODS

We acquired 64-direction diffusion-weighted magnetic resonance imaging on 25 euthymic bipolar I disorder subjects and 24 gender- and age-equivalent healthy subjects. White matter integrity measures including fractional anisotropy and mean diffusivity were compared in the whole brain. Additionally, structural connectivity matrices based on whole-brain deterministic tractography were constructed, followed by the computation of both global and local brain network measures. We also designed novel metrics to further probe inter-hemispheric integration.

RESULTS

Network analyses revealed that the bipolar brain networks exhibited significantly longer characteristic path length, lower clustering coefficient, and lower global efficiency relative to those of control subjects. Further analyses revealed impaired inter-hemispheric but relatively preserved intra-hemispheric integration. These findings were supported by whole-brain white matter analyses that revealed significantly lower integrity in the corpus callosum in bipolar subjects. There were also abnormalities in nodal network measures in structures within the limbic system, especially the left hippocampus, the left lateral orbitofrontal cortex, and the bilateral isthmus cingulate.

CONCLUSIONS

These results suggest abnormalities in structural network organization in bipolar disorder, particularly in inter-hemispheric integration and within the limbic system.

A high throughput and sensitive method correlates neuronal disorder genotypes to Drosophila larvae crawling phenotypes

Drosophila melanogaster is widely used as a model system for development and disease. Due to the homology between Drosophila and human genes, as well as the tractable genetics of the fly, its use as a model for neurologic disorders, in particular, has been rising. Locomotive impairment is a commonly used diagnostic for screening and characterization of these models, yet a fast, sensitive and model-free method to compare behavior is lacking. Here, we present a high throughput method to quantify the crawling behavior of larvae. We use the mean squared displacement as well as the direction autocorrelation of the crawling larvae as descriptors of their motion. By tracking larvae from wild-type strains and models of the Fragile X mental retardation as well as Alzheimer disease, we show these mutants exhibit impaired crawling. We further show that the magnitude of impairment correlates with the severity of the mutation, demonstrating the sensitivity and the dynamic range of the method. Finally, we study larvae with altered expression of the shaggy gene, a homolog of Glycogen Synthase Kinase-3 (GSK-3), which has been implicated in Alzheimer disease. Surprisingly, we find that both increased and decreased expression of dGSK-3 lead to similar larval crawling impairment. These findings have implications for the use of GSK-3 inhibitors recently proposed for Alzheimer treatment.

Acquired lithium resistance revisited: discontinuation-induced refractoriness versus tolerance

BACKGROUND

While some patients fail to respond to lithium from the outset, others are initially responsive and then develop treatment resistance. These acquired forms of lithium resistance have received relatively little clinical attention.

METHODS

We review the literature on the two different forms of acquired treatment resistance lithium that occur following an initial good response to lithium-discontinuation-induced refractoriness and tolerance- and discuss the possible neurobiological mechanisms involved.

RESULTS

Multiple investigators have reported cases of discontinuation-induced refractoriness, where following a good long-term response, patients discontinue lithium, suffer a major recurrence, and then do not again respond as well or at all to lithium once it is reinstituted at previously effective doses. The development of tolerance has similarly been multiply documented where lithium doses are consistently maintained, but after an extended period of excellent responsiveness, affective episodes of increasing severity, frequency, or duration begin to break through. These two forms of acquired treatment resistance appear to have different underlying neurobiological mechanisms and require differential treatment strategies.

LIMITATIONS

Recognition of acquired forms of lithium resistance depends on careful case descriptions and longitudinal monitoring of patients who are usually treated naturalistically and not in controlled clinical trials.

CONCLUSION

To the extent that these forms of acquired lithium resistance can be better recognized and their development slowed, prevented, or ameliorated, it could yield substantial clinical and public health benefits in avoiding the morbidity and mortality that can accompany lithium non-responsive bipolar disorder.

Hypothesis review: are clathrin-mediated endocytosis and clathrin-dependent membrane and protein trafficking core pathophysiological processes in schizophrenia and bipolar disorder?

Clathrin-mediated endocytosis (CME) is the best-characterized mechanism governing cellular membrane and protein trafficking. In this hypothesis review, we integrate recent evidence implicating CME and related cellular trafficking mechanisms in the pathophysiology of psychotic disorders such as schizophrenia and bipolar disorder. The evidence includes proteomic and genomic findings implicating proteins and genes of the clathrin interactome. Additionally, several important candidate genes for schizophrenia, such as dysbindin, are involved in processes closely linked to CME and membrane trafficking. We discuss that key aspects of psychosis neuropathology such as synaptic dysfunction, white matter changes and aberrant neurodevelopment are all influenced by clathrin-dependent processes, and that other cellular trafficking mechanisms previously linked to psychoses interact with the clathrin interactome in important ways. Furthermore, many antipsychotic drugs have been shown to affect clathrin-interacting proteins. We propose that the targeted pharmacological manipulation of the clathrin interactome may offer fruitful opportunities for novel treatments of schizophrenia.

Analysis of target genes regulated by chronic electroconvulsive therapy reveals role for Fzd6 in depression

BACKGROUND

Chronic electroconvulsive seizure (chr-ECS), one of the most efficacious treatments for depressed patients, increases the levels of transcription factor cyclic adenosine monophosphate response element binding protein (CREB) in rodent models and mediates the effects of chronic antidepressant treatment. The objective of this study was to determine the changes in CREB occupancy at gene promoters and subsequent gene expression changes induced by chr-ECS.

METHODS

We use chromatin immunoprecipitation followed by microarray analysis to identify CREB binding promoters that are influenced by chr-ECS (n = 6/group). Selected genes are confirmed by secondary validation techniques, and the functional significance of one target was tested in behavioral models (n = 8/group) by viral mediated inhibition of gene expression.

RESULTS

The results demonstrate that chr-ECS enhances CREB binding and activity at a select population of genes in the hippocampus, effects that could contribute to the efficacy of chr-ECS. Viral vector-mediated inhibition of one of the CREB-target genes regulated by chr-ECS, Fzd6, produced anxiety and depressive-like effects in behavioral models of depression.

CONCLUSIONS

The results identify multiple gene targets differentially regulated by CREB binding in the hippocampus after chr-ECS and demonstrate the role of Fzd6, a Wnt receptor in behavioral models of depression.

Beneficial effects of mood stabilizers lithium, valproate and lamotrigine in experimental stroke models

The mood stabilizers lithium, valproate and lamotrigine are traditionally used to treat bipolar disorder. However, accumulating evidence suggests that these drugs have broad neuroprotective properties and may therefore be promising therapeutic agents for the treatment of neurodegenerative diseases, including stroke. Lithium, valproate and lamotrigine exert protective effects in diverse experimental stroke models by acting on their respective primary targets, ie, glycogen synthase kinase-3, histone deacetylases and voltage-gated sodium channels, respectively. This article reviews the most recent findings regarding the underlying mechanisms of these phenomena, which will pave the way for clinical investigations that use mood stabilizers to treat stroke. We also propose several future research avenues that may extend our understanding of the benefits of lithium, valproate and lamotrigine in improving stroke outcomes.

Lithium ameliorates neurodegeneration, suppresses neuroinflammation, and improves behavioral performance in a mouse model of traumatic brain injury

Although traumatic brain injury (TBI) is recognized as one of the leading causes of death from trauma to the central nervous system (CNS), no known treatment effectively mitigates its effects. Lithium, a primary drug for the treatment of bipolar disorder, has been known to have neuroprotective effects in various neurodegenerative conditions such as stroke. Until this study, however, it has not been investigated as a post-insult treatment for TBI. To evaluate whether lithium could have beneficial effects following TBI, lithium at a dose of 1.5 mEq/kg was administered after injury. Assessed at 3 days and 3 weeks post-injury using hematoxylin and eosin staining, lithium treatment was found to reduce lesion volume. Lithium at doses of 2.0 and 3.0 mEq/kg also significantly reduced lesion volume at 3 days after injury, and the therapeutic window was at least 3 h post-injury. TBI-induced neuronal death, microglial activation, and cyclooxygenase-2 induction were all attenuated by lithium at 3 days after injury. In addition, lithium treatment reduced TBI-induced matrix metalloproteinase-9 expression and preserved the integrity of the blood-brain barrier. As for behavioral outcomes, lithium treatment reduced anxiety-like behavior in an open-field test, and improved short- and long-term motor coordination in rotarod and beam-walk tests. Lithium robustly increased serine phosphorylation of glycogen synthase kinase-3β (GSK-3β), suggesting that the underlying mechanisms responsible for lithium's protective effects are triggered by increasing phosphorylation of this kinase and thereby inhibiting its activity. Our results support the notion that lithium has heretofore unrecognized capacity to mitigate the neurodegenerative effects and improve functional outcomes in TBI.

GSK-3 Inhibitors: Preclinical and Clinical Focus on CNS

Inhibiting glycogen synthase kinase-3 (GSK-3) activity via pharmacological intervention has become an important strategy for treating neurodegenerative and psychiatric disorders. The known GSK-3 inhibitors are of diverse chemotypes and mechanisms of action and include compounds isolated from natural sources, cations, synthetic small-molecule ATP-competitive inhibitors, non-ATP-competitive inhibitors, and substrate-competitive inhibitors. Here we describe the variety of GSK-3 inhibitors with a specific emphasis on their biological activities in neurons and neurological disorders. We further highlight our current progress in the development of non-ATP-competitive inhibitors of GSK-3. The available data raise the hope that one or more of these drug design approaches will prove successful at stabilizing or even reversing the aberrant neuropathology and cognitive deficits of certain central nervous system disorders.

Protocol for a double-blind randomised placebo-controlled trial of lithium carbonate in patients with amyotrophic lateral sclerosis (LiCALS) [Eudract number: 2008-006891-31]

Background

Amyotrophic lateral sclerosis is a rapidly progressive neurodegenerative disorder characterised by loss of motor neurons leading to severe weakness and death from respiratory failure within 3-5 years. Riluzole prolongs survival in ALS. A published report has suggested a dramatic effect of lithium carbonate on survival. 44 patients were studied, with 16 randomly selected to take LiCO₃ and riluzole and 28 allocated to take riluzole alone. In the group treated with lithium, no patients had died (i.e., 100% survival) at the end of the study (15 months from entry), compared to 71% surviving in the riluzole-only group. Although the trial can be criticised on several grounds, there is a substantial rationale from other laboratory studies that lithium is worth investigating therapeutically in amyotrophic lateral sclerosis.

Methods/Design

LiCALS is a multi-centre double-blind randomised parallel group controlled trial of the efficacy, safety, and tolerability of lithium carbonate (LiCO₃) at doses to achieve stable 'therapeutic' plasma levels (0.4-0.8 mmol/L), plus standard treatment, versus matched placebo plus standard treatment, in patients with amyotrophic lateral sclerosis. The study will be based in the UK, in partnership with the MND Association and DeNDRoN (the Dementias and Neurodegnerative Diseases Clinical Research Network). 220 patients will be recruited. All patients will be on the standard treatment for ALS of riluzole 100 mg daily. The primary outcome measure will be death from any cause at 18 months defined from the date of randomisation. Secondary outcome measures will be changes in three functional rating scales, the ALS Functional Rating Scale-Revised, The EuroQOL (EQ-5D), and the Hospital Anxiety and Depression Scale.

Eligible patients will have El Escorial Possible, Laboratory-supported Probable, Probable or Definite amyotrophic lateral sclerosis with disease duration between 6 months and 36 months (inclusive), vital capacity ≥ 60% of predicted within 1 month prior to randomisation and age at least18 years.

Discussion

Patient recruitment began in June 2009 and the last patient is expected to complete the trial protocol in November 2011.

Trial registration

Current controlled trials ISRCTN83178718

Disease-modifying properties of long-term lithium treatment for amnestic mild cognitive impairment: randomised controlled trial

BACKGROUND

Two recent clinical studies support the feasibility of trials to evaluate the disease-modifying properties of lithium in Alzheimer's disease, although no benefits were obtained from short-term treatment.

AIMS

To evaluate the effect of long-term lithium treatment on cognitive and biological outcomes in people with amnestic mild cognitive impairment (aMCI).

METHOD

Forty-five participants with aMCI were randomised to receive lithium (0.25-0.5 mmol/l) (n = 24) or placebo (n = 21) in a 12-month, double-blind trial. Primary outcome measures were the modification of cognitive and functional test scores, and concentrations of cerebrospinal fluid (CSF) biomarkers (amyloid-beta peptide (Aβ(42)), total tau (T-tau), phosphorylated-tau) (P-tau).

TRIAL REGISTRATION

NCT01055392.

RESULTS

Lithium treatment was associated with a significant decrease in CSF concentrations of P-tau (P = 0.03) and better perform-ance on the cognitive subscale of the Alzheimer's Disease Assessment Scale and in attention tasks. Overall tolerability of lithium was good and the adherence rate was 91%.

CONCLUSIONS

The present data support the notion that lithium has disease-modifying properties with potential clinical implications in the prevention of Alzheimer's disease.

Higher BDNF serum levels predict slower cognitive decline in Alzheimer's disease patients

The neurotrophin brain-derived neurotrophic factor (BDNF) plays a critical role in neuronal survival, synaptic plasticity, and memory. Several recent studies have demonstrated altered BDNF serum levels in Alzheimer's disease (AD) patients. However, the association of BDNF serum levels with the rate of cognitive decline in AD patients is still unclear. We demonstrate that BDNF serum levels are significantly decreased in AD patients with fast cognitive decline [decrease of Mini-Mental State Examination (MMSE) score >4/yr; n=12] compared to AD patients with slow cognitive decline (decrease of MMSE score ≤4/yr, n=28) and show a significant correlation with the rate of cognitive decline during 1 yr follow-up. These results suggest that higher BDNF serum levels are associated with a slower rate of cognitive decline in AD patients. Further longitudinal studies are necessary to elucidate the kinetics and the potential role of serum BDNF as a surrogate marker of disease progression in AD patients.

Molecular actions and therapeutic potential of lithium in preclinical and clinical studies of CNS disorders

Lithium has been used clinically to treat bipolar disorder for over half a century, and remains a fundamental pharmacological therapy for patients with this illness. Although lithium's therapeutic mechanisms are not fully understood, substantial in vitro and in vivo evidence suggests that it has neuroprotective/neurotrophic properties against various insults, and considerable clinical potential for the treatment of several neurodegenerative conditions. Evidence from pharmacological and gene manipulation studies support the notion that glycogen synthase kinase-3 inhibition and induction of brain-derived neurotrophic factor-mediated signaling are lithium's main mechanisms of action, leading to enhanced cell survival pathways and alteration of a wide variety of downstream effectors. By inhibiting N-methyl-D-aspartate receptor-mediated calcium influx, lithium also contributes to calcium homeostasis and suppresses calcium-dependent activation of pro-apoptotic signaling pathways. In addition, lithium decreases inositol 1,4,5-trisphosphate by inhibiting phosphoinositol phosphatases, a process recently identified as a novel mechanism for inducing autophagy. Through these mechanisms, therapeutic doses of lithium have been demonstrated to defend neuronal cells against diverse forms of death insults and to improve behavioral as well as cognitive deficits in various animal models of neurodegenerative diseases, including stroke, amyotrophic lateral sclerosis, fragile X syndrome, as well as Huntington's, Alzheimer's, and Parkinson's diseases, among others. Several clinical trials are also underway to assess the therapeutic effects of lithium for treating these disorders. This article reviews the most recent findings regarding the potential targets involved in lithium's neuroprotective effects, and the implication of these findings for the treatment of a variety of diseases.

The mood stabilizers valproic acid and lithium enhance mesenchymal stem cell migration via distinct mechanisms

Mesenchymal stem cells (MSCs) show high potential for the therapy of several human diseases; however, the effectiveness of MSC transplantation has been hampered by the relatively poor migratory capacity of these cells toward disease target sites. This study investigated whether treatment of MSCs with two mood stabilizers-valproic acid (VPA) and lithium-would enhance cell migration and, if so, to explore the mechanisms underlying their effects. Short-term (3 h) exposure of MSCs to a relatively high concentration (2.5 mM) of VPA markedly increased the transcript and protein levels of CXC chemokine receptor 4 (CXCR4). VPA-induced CXCR4 expression required inhibition of histone deacetylases (HDACs), including the HDAC1 isoform, and involved histone hyperacetylation at the promoter region of the CXCR4 gene. Notably, VPA treatment enhanced stromal cell-derived factor-1α (SDF-1α)-mediated MSC migration, which was completely blocked by AMD3100, a CXCR4 antagonist. Treatment of MSCs with lithium (2.5 mM for 1 day) selectively elevated the transcript and protein levels of matrix metalloproteinase-9 (MMP-9) and its enzymatic activity; these effects were mimicked by inhibition or gene silencing of glycogen synthase kinase-3β (GSK-3β). Lithium treatment also potentiated SDF-1α-dependent MSC migration across the extracellular matrix, which was suppressed by two MMP-9 inhibitors, doxycycline and GM6001. Combining VPA and lithium treatment further increased MSC migration. Overall, VPA and lithium stimulated MSC migration through distinct targets and mediators: HDAC-CXCR4 and GSK-3β-MMP-9, respectively.

Wnt2 expression and signaling is increased by different classes of antidepressant treatments

BACKGROUND

Despite recent interest in glycogen synthase kinase-3beta (GSK-3beta) as a target for the treatment of mood disorders, there has been very little work related to these illnesses on the upstream signaling molecules that regulate this kinase as well as downstream targets.

METHODS

With a focused microarray approach we examined the influence of different classes of antidepressants on Wnt signaling that controls GSK-3beta activity as well as the transcription factors that contribute to the actions of GSK-3beta.

RESULTS

The results demonstrate that Wnt2 is a common target of different classes of antidepressants and also show differential regulation of Wnt-GSK-3beta signaling genes. Increased expression and function of Wnt2 was confirmed by secondary measures. Moreover, with a viral vector approach we demonstrate that increased expression of Wnt2 in the hippocampus is sufficient to produce antidepressant-like behavioral actions in well-established models of depression and treatment response.

CONCLUSIONS

These findings demonstrate that Wnt2 expression and signaling is a common target of antidepressants and that increased Wnt2 is sufficient to produce antidepressant effects.

Lithium-induced gray matter volume increase as a neural correlate of treatment response in bipolar disorder: a longitudinal brain imaging study

Preclinical studies suggest that lithium may exert neurotrophic effects that counteract pathological processes in the brain of patients with bipolar disorder (BD). To describe and compare the course and magnitude of gray matter volume changes in patients with BD who are treated with lithium or valproic acid (VPA) compared to healthy comparison subjects, and to assess clinical relationships to gray matter volume changes induced by lithium in patients with BD, we conducted longitudinal brain imaging and clinical evaluations of treatment response in 22 mood-stabilizing and antipsychotic medications-naive patients with BD who were randomly assigned to either lithium or VPA treatment after baseline assessment. Fourteen healthy comparison subjects did not take any psychotropic medications during follow-up. Longitudinal data analyses of 93 serial magnetic resonance images revealed lithium-induced increases in gray matter volume, which peaked at week 10-12 and were maintained through 16 weeks of treatment. This increase was associated with positive clinical response. In contrast, VPA-treated patients with BD or healthy comparison subjects did not show gray matter volume changes over time. Results suggest that lithium induces sustained increases in cerebral gray matter volume in patients with BD and that these changes are related to the therapeutic efficacy of lithium.

Potential mechanisms involved in the prevention of neurodegenerative diseases by lithium

Lithium is a monovalent cation that was introduced in 1949 by John Cade for the treatment of bipolar disorder. Clinical reports and subsequent studies confirmed this application and the beneficial effects of this compound. However, over the last 15 years, various authors have also demonstrated the neuroprotective effects of lithium against several neurotoxic paradigms. Thus, experimental studies in neuronal cell cultures and animal models of Alzheimer disease and others pathologies have provided strong evidence for the potential benefits of lithium. The main mechanism underlying its neuroprotective effects is thought to be inhibition of glycogen synthase kinase-3 (GSK-3), although other biochemical pathways in the brain could also be affected. In this review, the main mechanisms of lithium action are summarized, including the modulation of glutamate receptors, effects on arachidonic acid metabolism, its role with respect to AKT, and other potential mechanisms. In addition, its effects on neuroprotective proteins such as Bcl-2 and p53 are also discussed. Although the cellular and molecular biological effects of lithium may constitute an effective therapeutic strategy for Alzheimer disease, further clinical and experimental studies with this drug and specific GSK-3 inhibitors are necessary to confirm the use of lithium in therapeutic approaches to neurodegenerative diseases.

Neuronal damage and protection in the pathophysiology and treatment of psychiatric illness: stress and depression

The discovery that stress and depression, as well as other psychiatric illnesses, are characterized by structural alterations, and that these changes result from atrophy and loss of neurons and glia in specific limbic regions and circuits, has contributed to a fundamental change in our understanding of these illnesses. These structural changes are accompanied by dysregulation of neuroprotective and neurotrophic signaling mechanisms that are required for the maturation, growth, and survival of neurons and glia. Conversely, behavioral and therapeutic interventions can reverse these structural alterations by stimulating neuroprotective and neurotrophic pathways and by blocking the damaging, excitotoxic, and inflammatory effects of stress. Lifetime exposure to cellular and environmental stressors and interactions with genetic factors contribute to individual susceptibility or resilience. This exciting area of research holds promise and potential for further elucidating the pathophysiology of psychiatric illness and for development of novel therapeutic interventions.

The neurotrophic and neuroprotective effects of psychotropic agents

Accumulating evidence suggests that psychotropic agents such as mood stabilizers, antidepressants, and antipsychotics realize their neurotrophic/neuroprotective effects by activating the mitogen activated protein kinaselextracellular signal-related kinase, PI3-kinase, and winglesslglycogen synthase kinase (GSK) 3 signaling pathways. These agents also upregulate the expression of trophic/protective molecules such as brain-derived neurotrophic factor, nerve growth factor, B-cell lymphoma 2, serine-threonine kinase, and Bcl-2 associated athanogene 1, and inactivate proapoptotic molecules such as GSK-3, They also promote neurogenesis and are protective in models of neurodegenerative diseases and ischemia. Most if not all, of this evidence was collected from animal studies that used clinically relevant treatment regimens. Furthermore, human imaging studies have found that these agents increase the volume and density of brain tissue, as well as levels of N-acetyl aspartate and glutamate in selected brain regions. Taken together, these data suggest that the neurotrophic/neuroprotective effects of these agents have broad therapeutic potential in the treatment, not only of mood disorders and schizophrenia, but also neurodegenerative diseases and ischemia.

Neurobiological trait abnormalities in bipolar disorder

Dissecting trait neurobiological abnormalities in bipolar disorder (BD) from those characterizing episodes of mood disturbance will help elucidate the aetiopathogenesis of the illness. This selective review highlights the immunological, neuroendocrinological, molecular biological and neuroimaging abnormalities characteristic of BD, with a focus on those likely to reflect trait abnormalities by virtue of their presence in euthymic patients or in unaffected relatives of patients at high genetic liability for illness. Trait neurobiological abnormalities of BD include heightened pro-inflammatory function and hypothalamic-pituitary-adrenal axis dysfunction. Dysfunction in the intracellular signal transduction pathway is indicated by elevated protein kinase A activity and altered intracellular calcium signalling. Consistent neuroimaging abnormalities include the presence of ventricular enlargement and white matter abnormalities in patients with BD, which may represent intermediate phenotypes of illness. In addition, spectroscopy studies indicate reduced prefrontal cerebral N-acetylaspartate and phosphomonoester concentrations. Functional neuroimaging studies of euthymic patients implicate inherently impaired neural networks subserving emotional regulation, including anterior limbic, ventral and dorsal prefrontal regions. Despite heterogeneous samples and conflicting findings pervading the literature, there is accumulating evidence for the existence of neurobiological trait abnormalities in BD at various scales of investigation. The aetiopathogenesis of BD will be better elucidated by future clinical research studies, which investigate larger and more homogenous samples and employ a longitudinal design to dissect neurobiological abnormalities that are underlying traits of the illness from those related to episodes of mood exacerbation or pharmacological treatment.

No benefit from chronic lithium dosing in a sibling-matched, gender balanced, investigator-blinded trial using a standard mouse model of familial ALS

Background

In any animal model of human disease a positive control therapy that demonstrates efficacy in both the animal model and the human disease can validate the application of that animal model to the discovery of new therapeutics. Such a therapy has recently been reported by Fornai et al. using chronic lithium carbonate treatment and showing therapeutic efficacy in both the high-copy SOD1G93A mouse model of familial amyotrophic lateral sclerosis (ALS), and in human ALS patients.

Methodology/Principal Findings

Seeking to verify this positive control therapy, we tested chronic lithium dosing in a sibling-matched, gender balanced, investigator-blinded trial using the high-copy (average 23 copies) SOD1G93A mouse (n = 27–28/group). Lithium-treated mice received single daily 36.9 mg/kg i.p. injections from 50 days of age through death. This dose delivered 1 mEq/kg (6.94 mg/kg/day lithium ions). Neurological disease severity score and body weight were determined daily during the dosing period. Age at onset of definitive disease and survival duration were recorded. Summary measures from individual body weight changes and neurological score progression, age at disease onset, and age at death were compared using Kaplan-Meier and Cox proportional hazards analysis. Our study did not show lithium efficacy by any measure.

Conclusions/Significance

Rigorous survival study design that includes sibling matching, gender balancing, investigator blinding, and transgene copy number verification for each experimental subject minimized the likelihood of attaining a false positive therapeutic effect in this standard animal model of familial ALS. Results from this study do not support taking lithium carbonate into human clinical trials for ALS.

Bipolar disorder: from genes to behavior pathways

Bipolar disorder (BPD) is a devastating illness that is characterized by recurrent episodes of mania and depression. In addition to these cyclic episodes, individuals with BPD exhibit changes in psychovegetative function, cognitive performance, and general health and well being. In this article we draw from neuroimaging findings in humans, postmortem data, and human genetic and pharmacological studies as well as data from animal models of behavior to discuss the neurobiology of BPD. We conclude with a synthesis of where the field stands and with suggestions and strategies for future areas of study to further increase our conceptual understanding of this complex illness.

Bipolar disorder: from genes to behavior pathways

Bipolar disorder (BPD) is a devastating illness that is characterized by recurrent episodes of mania and depression. In addition to these cyclic episodes, individuals with BPD exhibit changes in psychovegetative function, cognitive performance, and general health and well being. In this article we draw from neuroimaging findings in humans, postmortem data, and human genetic and pharmacological studies as well as data from animal models of behavior to discuss the neurobiology of BPD. We conclude with a synthesis of where the field stands and with suggestions and strategies for future areas of study to further increase our conceptual understanding of this complex illness.

Lithium increases synapse formation between hippocampal neurons by depleting phosphoinositides

The mood-stabilizing effects of lithium are well documented, although its mechanism of action remains unknown. Increases in gray matter volume detected in patients with bipolar disorder who were treated with lithium suggest that changes in the number of synapses might underlie its therapeutic effects. We investigated the effects of lithium on the number of synaptic connections between hippocampal neurons in culture. Confocal imaging of neurons expressing postsynaptic density protein 95 fused to green fluorescent protein (PSD95-GFP) enabled visualization of synaptic sites. PSD95-GFP fluorescent puncta represented functional synapses, and lithium (4 h, 5 mM) increased their number by 150 +/- 12%. The increase was time- and concentration-dependent (EC(50) = 1.0 +/- 0.6 mM). Lithium induced a parallel increase in the presynaptic marker synaptophysin-GFP. Valproic acid, another mood stabilizer, also increased the number of fluorescent puncta at a clinically relevant concentration. Inhibition of postsynaptic glutamate receptors or presynaptic inhibition of neurotransmitter release significantly reduced lithium-induced synapse formation, indicating that glutamatergic synaptic transmission was required. Pretreatment with exogenous myo-inositol inhibited synapse formation, demonstrating that depletion of inositol was necessary to increase synaptic connections. In contrast, inhibition of glycogen synthase kinase 3beta did not mimic lithium-induced synapse formation. Pharmacological and lipid reconstitution experiments showed that new synapses formed as a result of depletion of phosphatidylinositol-4-phosphate rather than a build-up of polyphosphoinositides or changes in the activity of phospholipase C, protein kinase C, or phosphatidylinositol-3-kinase. Increased synaptic connections may underlie the mood-stabilizing effects of lithium in patients with bipolar disorder and could contribute to the convulsions produced by excessive doses of this drug.

Lithium and cognitive enhancement: leave it or take it?

RATIONALE

Lithium is established as an effective treatment of acute mania, bipolar and unipolar depression and as prophylaxis against bipolar disorder. Accumulating evidence is also delineating a neuroprotective and neurotrophic role for lithium. However, its primary effects on cognitive functioning remain ambiguous.

OBJECTIVES

The aim of this paper is to review and combine the relevant translational studies, focusing on the putative cognitive enhancement properties of lithium, specifically on learning, memory, and attention.

DISCUSSION

These properties are also discussed in reference to research demonstrating a protective action of lithium against cognitive deficits induced by various challenges to the nervous system, such as stress, trauma, neurodegenerative disorders, and psychiatric disorders.

CONCLUSIONS

It is suggested on the basis of the evidence that the cognitive effects of lithium are best expressed and should, therefore, be sought under conditions of functional or biological challenge to the nervous system.

Neuronal damage and protection in the pathophysiology and treatment of psychiatric illness: stress and depression

The discovery that stress and depression, as well as other psychiatric illnesses, are characterized by structural alterations, and that these changes result from atrophy and loss of neurons and glia in specific limbic regions and circuits, has contributed to a fundamental change in our understanding of these illnesses. These structural changes are accompanied by dysregulation of neuroprotective and neurotrophic signaling mechanisms that are required for the maturation, growth, and survival of neurons and glia. Conversely, behavioral and therapeutic interventions can reverse these structural alterations by stimulating neuroprotective and neurotrophic pathways and by blocking the damaging, excitotoxic, and inflammatory effects of stress. Lifetime exposure to cellular and environmental stressors and interactions with genetic factors contribute to individual susceptibility or resilience. This exciting area of research holds promise and potential for further elucidating the pathophysiology of psychiatric illness and for development of novel therapeutic interventions.

A feasibility and tolerability study of lithium in Alzheimer's disease

OBJECTIVE

To assess the safety and feasibility of prescribing long term lithium to elderly people with mild to moderate Alzheimer's disease (AD).

METHODS

An open label treatment group with low dose lithium for up to 1 year with the Lithium Side Effects Rating Scale as the primary outcome measure. A comparison group matched for cognition and age not receiving lithium therapy.

RESULTS

Twenty-two people with AD initiated lithium. Fourteen participants discontinued therapy after a mean of 16 weeks of treatment compared to the 39 weeks for those continuing to take treatment at the end of the study. Three patients discontinued treatment due to possible side effects that abated on ceasing therapy. The reports of side effects on the primary outcome scale did not differ between those discontinuing therapy and those remaining in the study. Two patients died whilst receiving lithium--in neither case was the treatment felt to be related to cause of death. There was no difference in deaths, drop outs or change in MMSE between those receiving lithium and the comparison group.

CONCLUSIONS

Lithium treatment in elderly people with AD has relatively few side effects and those that were apparently due to treatment were mild and reversible. Nonetheless discontinuation rates are high. The use of lithium as a potential disease modification therapy in AD should be explored further but is not without problems.

A molecular study of pathways involved in the inhibition of cell proliferation in neuroblastoma B65 cells by the GSK-3 inhibitors lithium and SB-415286

Pharmacological GSK-3 inhibitors are potential drugs for the treatment of neurodegenerative diseases, cancer and diabetes. We examined the antiproliferative effects of two GSK-3 inhibitors, lithium and SB-415286, on B65 neuroblastoma cell line. Treatment of B65 cells with either drug administered separately caused a decrease in cell proliferation that was associated with G₂/M cell cycle arrest. Cell-cycle proteins such as cyclins D, E, A, cdk4 and cdk2 were up-regulated. Since lithium and SB-415286-induced G₂/M arrest we studied changes in the expression of proteins involved in this phase, specifically cyclin B, cdc2 and the phosphorylated form of this protein (tyr15-cdc2). Both drugs increased the expression of tyr15-cdc2, thus inhibiting mitosis. On the other hand, SB-415286 increased the expression of SIRT2, involved in the regulation of proliferation. Moreover, cell-cycle arrest mediated by SB-415286 was accompanied by apoptosis that was not prevented by 100 μM of zVAD-fmk (benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone), a pan-caspase inhibitor. Likewise, GSK-3 inhibitors did not affect the mitochondrial release of apoptosis inducing factor (AIF). We conclude that inhibitors of GSK-3 induced cell-cycle arrest, mediated by the phosphorylation of cdc2 and, in the case of SB-415286, SIRT2 expression, which induced apoptosis in a caspase-independent manner.

Synergistic neuroprotective effects of lithium and valproic acid or other histone deacetylase inhibitors in neurons: roles of glycogen synthase kinase-3 inhibition

Lithium and valproic acid (VPA) are two primary drugs used to treat bipolar mood disorder and have frequently been used in combination to treat bipolar patients resistant to monotherapy with either drug. Lithium, a glycogen synthase kinase-3 (GSK-3) inhibitor, and VPA, a histone deacetylase (HDAC) inhibitor, have neuroprotective effects. The present study was undertaken to demonstrate synergistic neuroprotective effects when both drugs were coadministered. Pretreatment of aging cerebellar granule cells with lithium or VPA alone provided little or no neuroprotection against glutamate-induced cell death. However, copresence of both drugs resulted in complete blockade of glutamate excitotoxicity. Combined treatment with lithium and VPA potentiated serine phosphorylation of GSK-3 alpha and beta isoforms and inhibition of GSK-3 enzyme activity. Transfection with GSK-3alpha small interfering RNA (siRNA) and/or GSK-3beta siRNA mimicked the ability of lithium to induce synergistic protection with VPA. HDAC1 siRNA or other HDAC inhibitors (phenylbutyrate, sodium butyrate or trichostatin A) also caused synergistic neuroprotection together with lithium. Moreover, combination of lithium and HDAC inhibitors potentiated beta-catenin-dependent, Lef/Tcf-mediated transcriptional activity. An additive increase in GSK-3 serine phosphorylation was also observed in mice chronically treated with lithium and VPA. Together, for the first time, our results demonstrate synergistic neuroprotective effects of lithium and HDAC inhibitors and suggest that GSK-3 inhibition is a likely molecular target for the synergistic neuroprotection. Our results may have implications for the combined use of lithium and VPA in treating bipolar disorder. Additionally, combined use of both drugs may be warranted for clinical trials to treat glutamate-related neurodegenerative diseases.

Lithium blocks ethanol-induced modulation of protein kinases in the developing brain

Lithium has been shown to be neuroprotective against various insults including ethanol exposure. We previously reported that ethanol-induced apoptotic neurodegeneration in the postnatal day 7 (P7) mice is associated with decreases in phosphorylation levels of Akt, glycogen synthase kinase-3beta (GSK-3beta), and AMP-activated protein kinase (AMPK), and alteration in lipid profiles in the brain. Here, P7 mice were injected with ethanol and lithium, and the effects of lithium on ethanol-induced alterations in phosphorylation levels of protein kinases and lipid profiles in the brain were examined. Immunoblot and immunohistochemical analyses showed that lithium significantly blocked ethanol-induced caspase-3 activation and reduction in phosphorylation levels of Akt, GSK-3beta, and AMPK. Further, lithium inhibited accumulation of cholesterol ester (ChE) and N-acylphosphatidylethanolamine (NAPE) triggered by ethanol in the brain. These results suggest that Akt, GSK-3beta, and AMPK are involved in ethanol-induced neurodegeneration and the neuroprotective effects of lithium by modulating both apoptotic and survival pathways.