Lithium reduces Gsk3b mRNA levels: implications for Alzheimer Disease

Molecular mechanisms and therapeutic potential of lithium in Alzheimer's disease: repurposing an old class of drugs

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and memory loss. Despite advances in understanding the pathophysiological mechanisms of AD, effective treatments remain scarce. Lithium salts, recognized as mood stabilizers in bipolar disorder, have been extensively studied for their neuroprotective effects. Several studies indicate that lithium may be a disease-modifying agent in the treatment of AD. Lithium's neuroprotective properties in AD by acting on multiple neuropathological targets, such as reducing amyloid deposition and tau phosphorylation, enhancing autophagy, neurogenesis, and synaptic plasticity, regulating cholinergic and glucose metabolism, inhibiting neuroinflammation, oxidative stress, and apoptosis, while preserving mitochondrial function. Clinical trials have demonstrated that lithium therapy can improve cognitive function in patients with AD. In particular, meta-analyses have shown that lithium may be a more effective and safer treatment than the recently FDA-approved aducanumab for improving cognitive function in patients with AD. The affordability and therapeutic efficacy of lithium have prompted a reassessment of its use. However, the use of lithium may lead to potential side effects and safety issues, which may limit its clinical application. Currently, several new lithium formulations are undergoing clinical trials to improve safety and efficacy. This review focuses on lithium's mechanism of action in treating AD, highlighting the latest advances in preclinical studies and clinical trials. It also explores the side effects of lithium therapy and coping strategies, offering a potential therapeutic strategy for patients with AD.

The multifaceted role of Wnt canonical signalling in neurogenesis, neuroinflammation, and hyperexcitability in mesial temporal lobe epilepsy

Epilepsy is a neurological disorder characterised by unprovoked, repetitive seizures caused by abnormal neuronal firing. The Wnt/β-Catenin signalling pathway is involved in seizure-induced neurogenesis, aberrant neurogenesis, neuroinflammation, and hyperexcitability associated with epileptic disorder. Wnt/β-Catenin signalling is crucial for early brain development processes including neuronal patterning, synapse formation, and N-methyl-d-aspartate receptor (NMDAR) regulation. Disruption of molecular networks such as Wnt/β-catenin signalling in epilepsy could offer encouraging anti-epileptogenic targets. So, with a better understanding of the canonical Wnt/-Catenin pathway, we highlight in this review the important elements of Wnt/-Catenin signalling specifically in Mesial Temporal Lobe Epilepsy (MTLE) for potential therapeutic targets.

Could protein phosphatase 2A and glycogen synthase kinase-3 beta be targeted by natural compounds to ameliorate Alzheimer's pathologies?

Alzheimer's disease (AD) is a progressive neurological disorder that impairs memory and cognitive abilities, primarily in the elderly. The burden of AD extends beyond patients, impacting families and caregivers due to the patients' reliance on assistance for daily tasks. The main features of the pathogenesis of AD are beta-amyloid plaques and neurofibrillary tangles (NFTs), that strongly correlate with oxidative stress and inflammation. NFTs result from misfolded and hyperphosphorylated tau proteins. Various studies have focused on tau phosphorylation, indicating protein phosphatase 2A (PP2A) as the primary tau phosphatase and glycogen synthase kinase-3 beta (GSK-3β) as the leading tau kinase. Experimental evidence suggests that inhibition of PP2A and increased GSK-3β activity contribute to neuroinflammation, oxidative stress, and cognitive impairment. Hence, targeting PP2A and GSK-3β with pharmacological approaches shows promise in treating AD. The use of natural compounds in the drug development for AD have been extensively studied for their antioxidant, anti-inflammatory, anti-cholinesterase, and neuroprotective properties, demonstrating therapeutic advantages in neurological diseases. Alongside the development of PP2A activator and GSK-3β inhibitor drugs, natural compounds are likely to have neuroprotective effects by increasing PP2A activity and decreasing GSK-3β levels. Therefore, based on the preclinical and clinical studies, the potential of PP2A and GSK-3β as therapeutic targets of natural compounds are highlighted in this review.

Mitochondria dysfunction and bipolar disorder: From pathology to therapy

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

Lithium engages autophagy for neuroprotection and neuroplasticity: translational evidence for therapy

Here an overview is provided on therapeutic/neuroprotective effects of Lithium (Li⁺) in neurodegenerative and psychiatric disorders focusing on the conspicuous action of Li⁺ through autophagy. The effects on the autophagy machinery remain the key molecular mechanisms to explain the protective effects of Li⁺ for neurodegenerative diseases, offering potential therapeutic strategies for the treatment of neuropsychiatric disorders and emphasizes a crossroad linking autophagy, neurodegenerative disorders, and mood stabilization. Sensitization by psychostimulants points to several mechanisms involved in psychopathology, most also crucial in neurodegenerative disorders. Evidence shows the involvement of autophagy and metabotropic Glutamate receptors-5 (mGluR5) in neurodegeneration due to methamphetamine neurotoxicity as well as in neuroprotection, both in vitro and in vivo models. More recently, Li⁺ was shown to modulate autophagy through its action on mGluR5, thus pointing to an additional way of autophagy engagement by Li⁺ and to a substantial role of mGluR5 in neuroprotection related to neural e neuropsychiatry diseases. We propose Li⁺ engagement of autophagy through the canonical mechanisms of autophagy machinery and through the intermediary of mGluR5.

Cinnamaldehyde Regulates Insulin and Caspase-3 Signaling Pathways in the Sporadic Alzheimer's Disease Model: Involvement of Hippocampal Function via IRS-1, Akt, and GSK-3β Phosphorylation

Insulin signaling disruption and caspase-3 cleavage play a pathologic role in Alzheimer's disease (AD). Evidence suggested that cinnamaldehyde (Cin), the major component of cinnamon, has the ability to act as a neuroprotective agent. However, little evidence is available to demonstrate its effectiveness in regulating the insulin and caspase-3 signaling pathways and underlying molecular mechanisms. Therefore, the present study was conducted to correlate the molecular mechanisms of these signaling pathways and Cin treatment on animal behavioral performance in an intracerebroventricular (ICV)-streptozotocin (STZ, 3 mg/kg) model. The sporadic AD rat model was treated with Cin (10 and 100 mg/kg; intraperitoneal, i.p) daily for 2 weeks. Novel object recognition (NOR), Morris water maze (MWM), and elevated plus maze (EPM) tests were performed to assess recognition/spatial memory and anxiety-like behavior, respectively. Hippocampal Aβ aggregation was assessed using Congo red staining. The activity of hippocampal caspase-3 and IRS-1/Akt/GSK-3β signaling pathways were analyzed using the Western blot technique. The results revealed that Cin (100 mg/kg, effective dose) improved recognition/spatial memory deficits and anxiety-like behavior. In addition, Cin negated the effects of STZ on Aβ aggregation and caspase-3 cleavage in the hippocampus. Furthermore, the Western blot method showed that hippocampal IRS-1/AKT/GSK-3β phosphorylation was altered in ICV-STZ animal model, while Cin modulated this signaling pathway through decreasing Phospho.IRS-1_Ser307/Total.IRS-1 ratio and also increasing Phospho.Akt_Ser473/Total.Akt and Phospho.GSK-3β_Ser9/Total.GSK-3β ratios. These findings suggest that Cin is involved in the regulation of hippocampal IRS-1/AKT/GSK-3β and caspase-3 pathways in a sporadic AD model, and modulation of these signaling pathways also influences the animal behavioral performance.

Experimental data on lithium salts: From neuroprotection to multi-organ complications

Lithium-salts stand on the first line of therapy for the management of specific psychiatric conditions, mainly bipolar mood disorder. It is also known to protect the brain against neurodegenerative processes such as Alzheimer's disease. Despite the mentioned merits, recent studies have revealed that high dose or prolonged lithium intake deteriorate the function of multiple key organs including heart, ovaries, thyroid gland and kidneys. Mechanistically, both positive and negative effects of lithium are mediated through methylation of β-catenin nuclear-binding proteins which is potentiated by lithium-induced inhibition of GSK-3 or inositol monophosphatase. The current study briefly reviews the recent experimental data on lithium therapy considering both positive (i.e., neuroprotective) and negative aspects. In this regard, the question is that whether doses of lithium administered in experimental research are comparable with the therapeutic doses, as currently prescribed in clinical practice. It should be noted that the experimental data on animal studies, as widely reviewed here, could not be directly generalized to clinic. This is mainly because lithium doses applied in animal models are usually higher than therapeutic doses, however, there are evidence indicating that even animal to human translated doses of lithium, cause serious complications and this has been reported by meta-analyses on human studies. Therefore, we suggest the clinicians to use lithium-salts with precaution particularly in pregnancy and precisely adjust lithium concentration considering the patient's general health status to avoid lithium toxicity. Indeed, alternative approaches are recommended when the subject is pregnant, prolonged therapy is required or specific organ dysfunction is diagnosed.

Evaluating the neuroprotective activities of vinpocetine, punicalagin, niacin and vitamin E against behavioural and motor disabilities of manganese-induced Parkinson's disease in Sprague Dawley rats

The current study investigated the neuroprotective activity of some drugs and nutriceuticals with antioxidant and anti-inflammatory potential on the pathogenesis of Parkinson's disease (PD). Rats were categorized into seven groups: Rats received tween80 daily for 5 weeks as a control group, MnCl₂ (10 mg/kg, i.p) either alone (group II) or in combination with vinpocetine (VIN) (20 mg/kg) (group III), punicalagin (PUN) (30 mg/kg) (group IV), niacin (85 mg/kg) (group V), vitamin E (Vit E) (100 mg/kg) (group VI) or their combination (group VII). Motor activities was examined using open-field and catalepsy. Striatal monamines, acetylcholinesterase, excitatory/inhibitory neurotransmitters, redox status, pro-oxidant content, brain inflammatory, apoptotic and antioxidant biomarkers levels were assessed. Besides, histopathological investigations of different brain regions were determined. Groups (IV -GVII) showed improved motor functions of PD rats. Applied drugs significantly increased the brain levels of monoamines with the strongest effect to PUN. Meanwhile, they significantly decreased levels of acetylcholinesterase with a strongest effect to PUN. Moreover, they exhibited significant neuronal protection and anti-inflammatory abilities through significant reduction of the brain levels of COX2, TNF-α and Il-1β with a strongest effect to the PUN. Interestingly; groups (IV - GVII) showed restored glutamate/GABA balance and exhibited a pronounced decrease in caspase-3 content and GSK-3β protein expression levels. In addition, they significantly increased Bcl2 mRNA expression levels with a strongest effect for PUN. All these findings were further confirmed by the histopathological examinations. As a conclusion, we propose VIN and PUN to mitigate the progression of PD via their antioxidant, anti-inflammatory, anti-apoptotic, neurotrophic and neurogenic activities.

Role of Wnt signaling in synaptic plasticity and memory

Ever since their discoveries, the Wnt pathways have been consistently associated with key features of cellular development, including metabolism, structure and cell fate. The three known pathways (the canonical Wnt/β-catenin and the two non-canonical Wnt/Ca⁺⁺ and Wnt/JNK/PCP pathways) participate in complex networks of interaction with a wide range of regulators of cell function, such as GSK-3β, AKT, PKC and mTOR, among others. These proteins are known to be involved in the formation and maintenance of memory. Currently, studies with Wnt and memory have shown that the canonical and non-canonical pathways play key roles in different processes associated with memory. So, in this review we briefly summarize the different roles that Wnt signaling can play in neurons and in memory, as well as in Alzheimer's disease, focusing towards animal studies. We start with the molecular characterization of the family and its receptors, as well as the most commonly used drugs for pharmacological manipulations. Next, we describe its role in synaptic plasticity and memory, and how the regulations of these pathways affect crucial features of neuronal function. Furthermore, we succinctly present the current knowledge on how the Wnt pathways are implicated in Alzheimer's disease, and how studies are seeing them as a potential candidate for effective treatments. Lastly, we point toward challenges of Wnt research, and how knowledge on these pathways can lead towards a better understanding of neurobiological and pathological processes.

Lithium modulates multiple tau kinases with distinct effects in cortical and hippocampal neurons according to concentration ranges

The hyperphosphorylation of tau is a central mechanism in the pathogenesis of Alzheimer's disease (AD). Lithium is a potent inhibitor of glycogen synthase kinase-3beta (GSK3β), the most important tau kinase in neurons, and may also affect tau phosphorylation by modifying the expression and/or activity of other kinases, such as protein kinase A (PKA), Akt (PKB), and calcium calmodulin kinase-II (CaMKII). The aim of the present study is to determine the effect of chronic lithium treatment on the protein expression of tau and its major kinases in cortical and hippocampal neurons, at distinct working concentrations. Primary cultures of cortical and hippocampal neurons were treated with sub-therapeutic (0.02 mM and 0.2 mM) and therapeutic (2 mM) concentrations of lithium for 7 days. Protein expression of tau and tau-kinases was determined by immunoblotting. An indirect estimate of GSK3β activity was determined by the GSK3β ratio (rGSKβ). Statistically significant increments in the protein expression of tau and CaMKII were observed both in cortical and hippocampal neurons treated with subtherapeutic doses of lithium. GSK3β activity was increased in cortical, but decreased in hippocampal neurons. Distinct patterns of changes in the expression of the remaining tau tau-kinases were observed: in cortical neurons, lithium treatment was associated with consistent decrements in Akt and PKA, whereas hippocampal neurons displayed increased protein expression of Akt and decreased PKA. Our results suggest that chronic lithium treatment may yield distinct biological effects depending on the concentration range, with regional specificity. We further suggest that hippocampal neurons may be more sensitive to the effect of lithium, presenting with changes in the expression of tau-related proteins at subtherapeutic doses, which may not be mirrored by the effects observed in cortical neurons.

Macroautophagy and Mitophagy in Neurodegenerative Disorders: Focus on Therapeutic Interventions

Macroautophagy, a quality control mechanism, is an evolutionarily conserved pathway of lysosomal degradation of protein aggregates, pathogens, and damaged organelles. As part of its vital homeostatic role, macroautophagy deregulation is associated with various human disorders, including neurodegenerative diseases. There are several lines of evidence that associate protein misfolding and mitochondrial dysfunction in the etiology of Alzheimer’s, Parkinson’s, and Huntington’s diseases. Macroautophagy has been implicated in the degradation of different protein aggregates such as Aβ, tau, alpha-synuclein (α-syn), and mutant huntingtin (mHtt) and in the clearance of dysfunctional mitochondria. Taking these into consideration, targeting autophagy might represent an effective therapeutic strategy to eliminate protein aggregates and to improve mitochondrial function in these disorders. The present review describes our current understanding on the role of macroautophagy in neurodegenerative disorders and focuses on possible strategies for its therapeutic modulation.

Phenolic Profiling and Therapeutic Potential of Certain Isolated Compounds from Parkia roxburghii against AChE Activity as well as GABAA α5, GSK-3β, and p38α MAP-Kinase Genes

Parkia roxburghii belongs to the family Mimosaceae; it has been used since ancient times as a cure for different health complications; such as inflammatory and gynecological diseases and hemiplegia. In this investigation, a reversed-phase-high-performance liquid chromatography (RP-HPLC) profile was carried out for P. roxburghii; also, the isolated bioactive compounds including quercetin, catechin, and biochaninA were individually and/or in combination investigated for their inhibitory effects on scopolamine-induced memory impairments in mice, implying that they have the ability to reduce the neurodegenerative effects of scopolamine and thus could be employed as a more effective therapeutic agent in the treatment of Alzheimer's disease (AD) in humans. The possible interactions of Parkia flavonoids with acetylcholinesterase (AChE), γ-aminobutyric acid A receptor, alpha5 (GABA_A α5), glycogen synthase kinase-3 (GSK-3), p38 mitogen-activated protein kinase (p38MAP-kinase), signal-regulated kinase (ERK), and protein-serine/threonine kinase (Akt) were then determined using molecular docking.

Translational evidence for lithium-induced brain plasticity and neuroprotection in the treatment of neuropsychiatric disorders

Increasing evidence indicates lithium (Li+) efficacy in neuropsychiatry, pointing to overlapping mechanisms that occur within distinct neuronal populations. In fact, the same pathway depending on which circuitry operates may fall in the psychiatric and/or neurological domains. Li+ restores both neurotransmission and brain structure unveiling that psychiatric and neurological disorders share common dysfunctional molecular and morphological mechanisms, which may involve distinct brain circuitries. Here an overview is provided concerning the therapeutic/neuroprotective effects of Li+ in different neuropsychiatric disorders to highlight common molecular mechanisms through which Li+ produces its mood-stabilizing effects and to what extent these overlap with plasticity in distinct brain circuitries. Li+ mood-stabilizing effects are evident in typical bipolar disorder (BD) characterized by a cyclic course of mania or hypomania followed by depressive episodes, while its efficacy is weaker in the opposite pattern. We focus here on neural adaptations that may underlie psychostimulant-induced psychotic development and to dissect, through the sensitization process, which features are shared in BD and other psychiatric disorders, including schizophrenia. The multiple functions of Li+ highlighted here prove its exceptional pharmacology, which may help to elucidate its mechanisms of action. These may serve as a guide toward a multi-drug strategy. We propose that the onset of sensitization in a specific BD subtype may predict the therapeutic efficacy of Li+. This model may help to infer in BD which molecular mechanisms are relevant to the therapeutic efficacy of Li+.

Lithium: A therapeutic option in Alzheimer's disease and its prodromal stages?

Experimental data reveal that lithium is capable of attenuating Alzheimer's disease pathology and stimulating adult hippocampal neurogenesis. Clinical studies show procognitive effects in lithium-treated patients with amnestic MCI and Alzheimer's disease. These procognitive effects are associated with changes of CSF biomarkers of Alzheimer's disease. After 3 months of lithium treatment with low lithium levels, a slowing of cognitive decline is observed in patients with Alzheimer's disease. In patients with amnestic MCI with low-dose lithium treatment a trend of a reduced Alzheimer's disease conversion rate and longer cognitive stability was reported. Thus, lithium might be a therapeutic option in the treatment of Alzheimer's disease and its prodromal stages. But its therapeutic efficacy needs further evaluation. Further studies should include head-to-head comparisons with approved dementia treatment options. Due to lithium's therapeutic toxicity a thorough preselection of patients and a closely therapeutic monitoring is necessary. This manuscript is based on a literature review.

Autophagy-targeted therapy to modulate age-related diseases: Success, pitfalls, and new directions

Autophagy is a critical metabolic process that supports homeostasis at a basal level and is dynamically regulated in response to various physiological and pathological processes. Autophagy has some etiologic implications that support certain pathological processes due to alterations in the lysosomal-degradative pathway. Some of the conditions related to autophagy play key roles in highly relevant human diseases, e.g., cardiovascular diseases (15.5%), malignant and other neoplasms (9.4%), and neurodegenerative conditions (3.7%). Despite advances in the discovery of new strategies to treat these age-related diseases, autophagy has emerged as a therapeutic option after preclinical and clinical studies. Here, we discuss the pitfalls and success in regulating autophagy initiation and its lysosome-dependent pathway to restore its homeostatic role and mediate therapeutic effects for cancer, neurodegenerative, and cardiac diseases. The main challenge for the development of autophagy regulators for clinical application is the lack of specificity of the repurposed drugs, due to the low pharmacological uniqueness of their target, including those that target the PI3K/AKT/mTOR and AMPK pathway. Then, future efforts must be conducted to deal with this scenery, including the disclosure of key components in the autophagy machinery that may intervene in its therapeutic regulation. Among all efforts, those focusing on the development of novel allosteric inhibitors against autophagy inducers, as well as those targeting autolysosomal function, and their integration into therapeutic regimens should remain a priority for the field.

Is There Justification to Treat Neurodegenerative Disorders by Repurposing Drugs? The Case of Alzheimer's Disease, Lithium, and Autophagy

Lithium is the prototype mood-stabilizer used for acute and long-term treatment of bipolar disorder. Cumulated translational research of lithium indicated the drug's neuroprotective characteristics and, thereby, has raised the option of repurposing it as a drug for neurodegenerative diseases. Lithium's neuroprotective properties rely on its modulation of homeostatic mechanisms such as inflammation, mitochondrial function, oxidative stress, autophagy, and apoptosis. This myriad of intracellular responses are, possibly, consequences of the drug's inhibition of the enzymes inositol-monophosphatase (IMPase) and glycogen-synthase-kinase (GSK)-3. Here we review lithium's neurobiological properties as evidenced by its neurotrophic and neuroprotective properties, as well as translational studies in cells in culture, in animal models of Alzheimer's disease (AD) and in patients, discussing the rationale for the drug's use in the treatment of AD.

Neuronal-Glial Interaction in a Triple-Transgenic Mouse Model of Alzheimer's Disease: Gene Ontology and Lithium Pathways

Neuronal-glial interactions are critical for brain homeostasis, and disruption of this process may lead to excessive glial activation and inadequate pro-inflammatory responses. Abnormalities in neuronal-glial interactions have been reported in the pathophysiology of Alzheimer’s disease (AD), where lithium has been shown to exert neuroprotective effects, including the up-regulation of cytoprotective proteins. In the present study, we characterize by Gene Ontology (GO) the signaling pathways related to neuronal-glial interactions in response to lithium in a triple-transgenic mouse model of AD (3×-TgAD). Mice were treated for 8 months with lithium carbonate (Li) supplemented to chow, using two dose ranges to yield subtherapeutic working concentrations (Li1, 1.0 g/kg; and Li2, 2.0 g/kg of chow), or with standard chow (Li0). The hippocampi were removed and analyzed by proteomics. A neuronal-glial interaction network was created by a systematic literature search, and the selected genes were submitted to STRING, a functional network to analyze protein interactions. Proteomics data and neuronal-glial interactomes were compared by GO using ClueGo (Cytoscape plugin) with p ≤ 0.05. The proportional effects of neuron-glia interactions were determined on three GO domains: (i) biological process; (ii) cellular component; and (iii) molecular function. The gene ontology of this enriched network of genes was further stratified according to lithium treatments, with statistically significant effects observed in the Li2 group (as compared to controls) for the GO domains biological process and cellular component. In the former, there was an even distribution of the interactions occurring at the following functions: “positive regulation of protein localization to membrane,” “regulation of protein localization to cell periphery,” “oligodendrocyte differentiation,” and “regulation of protein localization to plasma membrane.” In cellular component, interactions were also balanced for “myelin sheath” and “rough endoplasmic reticulum.” We conclude that neuronal-glial interactions are implicated in the neuroprotective response mediated by lithium in the hippocampus of AD-transgenic mice. The effect of lithium on homeostatic pathways mediated by the interaction between neurons and glial cells are implicated in membrane permeability, protein synthesis and DNA repair, which may be relevant for the survival of nerve cells amidst AD pathology.

Blood biomarkers for memory: toward early detection of risk for Alzheimer disease, pharmacogenomics, and repurposed drugs

Short-term memory dysfunction is a key early feature of Alzheimer's disease (AD). Psychiatric patients may be at higher risk for memory dysfunction and subsequent AD due to the negative effects of stress and depression on the brain. We carried out longitudinal within-subject studies in male and female psychiatric patients to discover blood gene expression biomarkers that track short term memory as measured by the retention measure in the Hopkins Verbal Learning Test. These biomarkers were subsequently prioritized with a convergent functional genomics approach using previous evidence in the field implicating them in AD. The top candidate biomarkers were then tested in an independent cohort for ability to predict state short-term memory, and trait future positive neuropsychological testing for cognitive impairment. The best overall evidence was for a series of new, as well as some previously known genes, which are now newly shown to have functional evidence in humans as blood biomarkers: RAB7A, NPC2, TGFB1, GAP43, ARSB, PER1, GUSB, and MAPT. Additional top blood biomarkers include GSK3B, PTGS2, APOE, BACE1, PSEN1, and TREM2, well known genes implicated in AD by previous brain and genetic studies, in humans and animal models, which serve as reassuring de facto positive controls for our whole-genome gene expression discovery approach. Biological pathway analyses implicate LXR/RXR activation, neuroinflammation, atherosclerosis signaling, and amyloid processing. Co-directionality of expression data provide new mechanistic insights that are consistent with a compensatory/scarring scenario for brain pathological changes. A majority of top biomarkers also have evidence for involvement in other psychiatric disorders, particularly stress, providing a molecular basis for clinical co-morbidity and for stress as an early precipitant/risk factor. Some of them are modulated by existing drugs, such as antidepressants, lithium and omega-3 fatty acids. Other drug and nutraceutical leads were identified through bioinformatic drug repurposing analyses (such as pioglitazone, levonorgestrel, salsolidine, ginkgolide A, and icariin). Our work contributes to the overall pathophysiological understanding of memory disorders and AD. It also opens new avenues for precision medicine- diagnostics (assement of risk) as well as early treatment (pharmacogenomically informed, personalized, and preventive).

Lithium Pharmacology and a Potential Role of Lithium on Methamphetamine Abuse and Dependence

BACKGROUND

The effectiveness of lithium salts in neuropsychiatric disorders such as bipolar disorder, Alzheimer's disease, and treatment-resistant depression has been documented in an extensive scientific literature. Lithium inhibits inositol monophosphatase, inositol polyphosphate 1- phosphatase, and glycogen synthase kinase-3 and decreases expression level of tryptophan hydroxylase 2, conceivably underlying the mood stabilizing effects of lithium, as well as procognitive and neuroprotective effects. However, the exact molecular mechanisms of action of lithium on mood stabilizing and pro-cognitive effects in humans are still largely unknown.

OBJECTIVE

On the basis of the known aspects of lithium pharmacology, this review will discuss the possible mechanisms underlying the therapeutic effects of lithium on positive symptoms of methamphetamine abuse and dependence.

CONCLUSION

It is possible that lithium treatment reduces the amount of newly synthesized phosphatidylinositol, potentially preventing or reversing neuroadaptations contributing to behavioral sensitization induced by methamphetamine. In addition, it is suggested that exposure to repeated doses of methamphetamine induces hyperactivation of glycogen synthase kinase-3β in the nucleus accumbens and in dorsal hippocampus, resulting in a long-term alterations in synaptic plasticity underlying behavioral sensitization as well as other behavioral deficits in memory-related behavior. Therefore it is clear that glycogen synthase kinase-3β inhibitors can be considered as a potential candidate for the treatment of methamphetamine abuse and dependence.

GSK3β inhibition suppresses the hepatic lipid accumulation in Schizothorax prenanti

Glycogen synthase kinase-3β (GSK3β) is a serine/threonine kinase involved in the regulation of embryonic development, glycogen metabolism, protein synthesis, mitosis, and apoptosis. To understand the role of GSK3β in hepatic lipid accumulation of Schizothorax prenanti, we used lithium chloride (LiCl), a GSK3β inhibitor, to inhibit the expression and activity of GSK3β. LiCl increased levels of phosphorylation of GSK3β (Ser9) and decreased the protein level of GSK3β. Plasma TG, TC, and LDL-C levels were greatly decreased after LiCl treatment. Additionally, GSK3β inhibition significantly reduced the levels of hepatic triglyceride (TG) and decreased the expression of lipogenesis-related genes in liver. Interestingly, LiCl decreased levels of phosphorylation of STAT3 (Tyr705), and then inhibited the activity of STAT3. These results indicate that in vivo LiCl treatment, which inhibited GSK3β activity, effectively decreased hepatic lipid accumulation through STAT3 in Schizothorax prenanti.

Curcumin Downregulates GSK3 and Cdk5 in Scopolamine-Induced Alzheimer's Disease Rats Abrogating Aβ40/42 and Tau Hyperphosphorylation

Alzheimer's disease (AD) is the most common form of dementia. Extracellular amyloid-β (Aβ) aggregation and tau hyperphosphorylation are the key drivers of AD. Glycogen synthase kinase 3 (GSK3) and cyclin dependent kinase 5 (Cdk5) have been known as leading applicants arbitrating abnormal tau hyperphosphorylation. Thus, we evaluated the efficacy and underlying mechanism of action of curcumin in scopolamine-induced AD rats in our study. We found that curcumin-treated AD rats markedly reduced the levels of Aβ₄₀ and Aβ₄₂ in the brain and in the plasma in comparison to untreated AD rats. Moreover, the levels of phosphorylated tau at Ser396 (PHF13), Ser202/Thr205 (AT8), and Aβ_40/42 (MOAB2) were decreased significantly in AD rats treated with curcumin. Phospho-GSK3β (Tyr216), the active form of GSK3β, and total GSK3β were significantly decreased in AD rats treated with curcumin. Furthermore, Cdk5 and its activators p35 and p25 were significantly decreased in curcumin-treated AD rats. The reduced levels of Cdk5, p35, p25, and GSK3β in curcumin-treated AD rats may result decreased Aβ aggregation and tau hyperphosphorylation, thus ameliorating AD. Impaired spatial memory and locomotor activity in AD rats were partially reversed by curcumin. Therefore, curcumin, as a natural compound present in turmeric, may be a more effective therapeutic agent in the treatment of AD in humans.

Lithium-induced gene expression alterations in two peripheral cell models of bipolar disorder

Objectives: The aim of our study was to investigate molecular mechanisms of lithium action by studying the gene expression profile of peripheral cell models generated from bipolar patients (BD) and healthy controls (HC). Methods: EBV-immortalised lymphoblastoid cells (LCLs) and fibroblast cells from BD and HC were incubated with either lithium chloride or plain medium for 3 weeks. We first conducted a microarray gene expression study. The most promising differentially regulated genes in terms of lithium-associated or disorder-associated pathways were then replicated by quantitative real-time PCR (qRT-PCR). Results: The pooled microarray analysis showed 459 genes to be differentially regulated in BD compared to HC and 58 due to lithium treatment in LCLs, and 295 genes to be differentially regulated in BD compared to HC and five due to lithium treatment in fibroblasts. After correction for multiple comparison, EPHB1 disorder × treatment interactions remained significant in LCLs validated by qRT-PCR. In the control group, lithium influenced the expression of ANP32E, PLEKHA2, KCNK1, PRKCH, ST3GAL6 and AIF1. In bipolar and control fibroblast cells lithium treatment decreased FGF9 expression. Conclusions: The differentially regulated genes in our study add evidence for the relevance of inflammation, neuronal/glial development, phosphatidylinositol second-messenger pathway and ion channels in the mode of action of lithium.

Modulating Protein Phosphatase 2A Rescues Disease Phenotype in Neurodegenerative Tauopathies

Alzheimer's disease (AD) is the leading cause of dementia worldwide accounting for around 70% of all cases. There is currently no treatment for AD beyond symptom management and attempts at developing disease-modifying therapies have yielded very little. These strategies have traditionally targeted the peptide Aβ, which is thought to drive pathology. However, the lack of clinical translation of these Aβ-centric strategies underscores the need for diverse treatment strategies targeting other aspects of the disease. Metal dyshomeostasis is a common feature of several neurodegenerative diseases such as AD, Parkinson's disease, and frontotemporal dementia, and manipulation of metal homeostasis has been explored as a potential therapeutic avenue for these diseases. The copper ionophore glyoxalbis-[N4-methylthiosemicarbazonato]Cu(II) (Cu^II(gtsm)) has previously been shown to improve the cognitive deficits seen in an AD animal model; however, the molecular mechanism remained unclear. Here we report that the treatment of two animal tauopathy models (APP/PS1 and rTg4510) with Cu^II(gtsm) recovers the cognitive deficits seen in both neurodegenerative models. In both models, markers of tau pathology were significantly reduced with Cu^II(gtsm) treatment, and in the APP/PS1 model, the levels of Aβ remained unchanged. Analysis of tau kinases (GSK3β and CDK5) revealed no drug induced changes; however, both models exhibited a significant increase in the levels of the structural subunit of the tau phosphatase, PP2A. These findings suggest that targeting the tau phosphatase PP2A has therapeutic potential for preventing memory impairments and reducing the tau pathology seen in AD and other tauopathies.

Release of lithium from 3D printed polycaprolactone scaffolds regulates macrophage and osteoclast response

The immunomodulatory effects of lithium have been reported across a range of models and contexts. Lithium appears to have a positive effect on osteogenesis in vivo, while in vitro outcomes throughout the literature are varied. Tissue engineering approaches have rarely targeted local lithium delivery within a regenerative setting. We hypothesized that part of the positive effects of lithium in vivo may be due to an immunomodulatory effect manifesting in a local environment. To achieve a sustained lithium release from scaffold constructs, we blended lithium carbonate, a soluble salt of lithium, with the biomaterial polymer polycaprolactone (PCL). We printed constructs of PCL alone, and with 5% (5Li) and 10% (10Li) lithium carbonate. Mechanical testing revealed that mechanical properties were largely retained with lithium carbonate incorporation, and we measured a consistent release of the ion over a 7 day period. The efficacy of our construct system was then assessed using a primary mouse macrophage culture, and a differentiated osteoclast culture. We found that the lithium released from constructs had a great effect on macrophage polarization, resulting in pronounced upregulation of immunomodulatory (M2) genes, and a decrease in pro-inflammatory (M1) genes. This was reflected in cytokine expression, and illustrated through immunofluorescent staining. Osteoclast activity was greatly suppressed by the lithium incorporation, with a marked effect on gene expression and actin ring formation. Our work demonstrated an effective system for local lithium delivery, confirmed the pronounced effects that lithium has on macrophage and osteoclast response, and sets the stage for further innovations in ion release for targeted tissue engineering.

[Neurotrophic effects of lithium stimulate the reduction of ischemic and neurodegenerative brain damage]

For over 60 years, high doses of lithium (hundreds of milligrams of elemental lithium) have being used to treat bipolar disorder. However, only during the past 20 years the relevant basic and clinical studies have shown that neuroprotective and neurotrophic effects of lithium are possible in much smaller doses ( hundreds of micrograms of elemental lithium). These data indicate a significant potential for the clinical applications of lithium-based drugs in modern neurology for the purposes of prevention and treatment of neurodegenerative and ischemic pathologies. Pharmacological and molecular biology studies indicated that the inhibition of glycogen synthase kinase-syntentase-3 (GSK-3) and induction of brain-derived neurotrophic factors are the main mechanisms of neurotropic actions of lithium. Also, by inhibiting the NMDA receptors, lithium regulates the calcium homeostasis and inhibits the activation of calcium-dependent apotosis. These and other molecular mechanisms of lithium action protect neurons from ischemia and neurodegeneration thus contributing to a significant reduction of neurological deficit in various models of stroke and neurodegenerative diseases.

Lithium-associated transcriptional regulation of CRMP1 in patient-derived olfactory neurons and symptom changes in bipolar disorder

There is growing evidence that lithium used in the treatment of bipolar disorder (BD) affects molecular targets that are involved in neuronal growth, survival, and maturation, but it remains unclear if neuronal alterations in any of these molecules predict specific symptom changes in BD patients undergoing lithium monotherapy. The goals of this study were to (a) determine which molecular changes in the olfactory neurons of symptomatic patients receiving lithium are associated with antimanic or antidepressant response, and (b) uncover novel intraneuronal regulatory mechanisms of lithium therapy. Twenty-two treatment-naïve non-smoking patients, with symptomatic BD underwent nasal biopsies for collection of olfactory tissues, prior to their treatment and following a 6-week course of lithium monotherapy. Sixteen healthy controls were also biopsied. Combining laser capture microdissection with real-time polymerase chain reaction, we investigated baseline and treatment-associated transcriptional changes in candidate molecular targets of lithium action in the olfactory neuroepithelium. Baseline mRNA levels of glycogen synthase kinase 3 beta (GSK3β) and collapsin response mediator protein 1 (CRMP1) genes were significantly associated with BD status and with severity of mood symptoms. Among BD subjects, treatment-associated downregulation of CRMP1 expression was most predictive of decreases in both manic and depressive symptoms. This study provides a novel insight into the relevance of CRMP1, a key molecule in semaphorin-3A signaling during neurodevelopment, in the molecular mechanism of action of lithium, and in the pathophysiology of BD. It supports the use of human-derived olfactory neuronal tissues in the evaluation of treatment response of psychiatric disorders.

Towards a Unified Understanding of Lithium Action in Basic Biology and its Significance for Applied Biology

Lithium has literally been everywhere forever, since it is one of the three elements created in the Big Bang. Lithium concentration in rocks, soil, and fresh water is highly variable from place to place, and has varied widely in specific regions over evolutionary and geologic time. The biological effects of lithium are many and varied. Based on experiments in which animals are deprived of lithium, lithium is an essential nutrient. At the other extreme, at lithium ingestion sufficient to raise blood concentration significantly over 1 mM/, lithium is acutely toxic. There is no consensus regarding optimum levels of lithium intake for populations or individuals-with the single exception that lithium is a generally accepted first-line therapy for bipolar disorder, and specific dosage guidelines for sufferers of that condition are generally agreed on. Epidemiological evidence correlating various markers of social dysfunction and disease vs. lithium level in drinking water suggest benefits of moderately elevated lithium compared to average levels of lithium intake. In contrast to other biologically significant ions, lithium is unusual in not having its concentration in fluids of multicellular animals closely regulated. For hydrogen ions, sodium ions, potassium ions, calcium ions, chloride ions, and magnesium ions, blood and extracellular fluid concentrations are closely and necessarily regulated by systems of highly selective channels, and primary and secondary active transporters. Lithium, while having strong biological activity, is tolerated over body fluid concentrations ranging over many orders of magnitude. The lack of biological regulation of lithium appears due to lack of lithium-specific binding sites and selectivity filters. Rather lithium exerts its myriad physiological and biochemical effects by competing for macromolecular sites that are relatively specific for other cations, most especially for sodium and magnesium. This review will consider what is known about the nature of this competition and suggest using and extending this knowledge towards the goal of a unified understanding of lithium in biology and the application of that understanding in medicine and nutrition.

Xanthine-Catechin Mixture Enhances Lithium-Induced Anti-Inflammatory Response in Activated Macrophages In Vitro

Lithium (Li) is a chemical element used for treating and preventing bipolar disorder (BD) and exerts positive effects such as anti-inflammatory effects as well as undesirable side effects. These effects of Li can be influenced by interaction with some nutritional elements. Therefore, we investigated the potential effects of xanthine (caffeine and theobromine) and catechin molecules present in some food beverages broadly consumed worldwide, such as coffee and tea, on Li-induced anti-inflammatory effects. In the present study, we concomitantly exposed RAW 264.7 macrophages to Li, isolated xanthine and catechin molecules, and a xanthine-catechin mixture (XC mixture). We evaluated the effects of these treatments on cell proliferation, cell cycle progression, oxidative and antioxidant marker expression, cytokine levels, gene expression, and GSK-3β enzyme expression. Treatment with the XC mixture potentialized Li-induced anti-inflammatory effects by intensification of the following: GSK-3β inhibitory action, lowering effect on proinflammatory cytokines (IL-1β, IL-6, and TNFα), and increase in the levels of IL-10 that is an anti-inflammatory cytokine. Despite the controversial nature of caffeine consumption by BD patients, these results suggested that consumption of caffeine, in low concentrations, mixed with other bioactive molecules along with Li may be safe.

Proteomic Analysis of Mitochondria-Enriched Fraction Isolated from the Frontal Cortex and Hippocampus of Apolipoprotein E Knockout Mice Treated with Alda-1, an Activator of Mitochondrial Aldehyde Dehydrogenase (ALDH2)

The role of different genotypes of apolipoprotein E (apoE) in the etiology of Alzheimer’s disease is widely recognized. It has been shown that altered functioning of apoE may promote 4-hydroxynonenal modification of mitochondrial proteins, which may result in mitochondrial dysfunction, aggravation of oxidative stress, and neurodegeneration. Mitochondrial aldehyde dehydrogenase (ALDH2) is an enzyme considered to perform protective function in mitochondria by the detoxification of the end products of lipid peroxidation, such as 4-hydroxynonenal and other reactive aldehydes. The goal of our study was to apply a differential proteomics approach in concert with molecular and morphological techniques to elucidate the changes in the frontal cortex and hippocampus of apolipoprotein E knockout (apoE^−/−) mice upon treatment with Alda-1—a small molecular weight activator of ALDH2. Despite the lack of significant morphological changes in the brain of apoE^−/− mice as compared to age-matched wild type animals, the proteomic and molecular approach revealed many changes in the expression of genes and proteins, indicating the impairment of energy metabolism, neuroplasticity, and neurogenesis in brains of apoE^−/− mice. Importantly, prolonged treatment of apoE^−/− mice with Alda-1 led to the beneficial changes in the expression of genes and proteins related to neuroplasticity and mitochondrial function. The pattern of alterations implies mitoprotective action of Alda-1, however, the accurate functional consequences of the revealed changes require further research.

The gender-specific association of rs334558 in GSK3β with major depressive disorder

Major depressive disorder (MDD) is one of the most prevalent psychiatric illnesses with a heritability ranging from 40% to 50%. The single nucleotide polymorphism (SNP) rs334558 on the glycogen synthase kinase-3β (GSK3β) gene has been identified as a genetic risk loci associated with schizophrenia and bipolar disorder. However, results from replication studies examining the association between rs334558 and MDD remain inconsistent.In the present study, first, we conducted a meta-analysis of the association between rs334558 and MDD by combining 5 available case-control samples totaling 2311 cases and 2535 controls. Second, genotyping data from patients with MDD at our institution, after further stratification by gender, were analyzed to determine the association between rs334558 and MDD.All studies retrieved and included in the meta-analysis were from Korea and China. The meta-analysis suggested that the functional polymorphism rs334558 within the GSK3β promoter region was associated with MDD risk (P < 0.05). The associations were observed both in the allelic and genetic models. Analysis of the genotyping data extracted from our hospital database revealed that rs334558 exhibited exclusive association with MDD in female patients (P=0.015).Our findings suggest that GSK3β rs334558 polymorphisms might be a potential risk for MDD, and females with GSK3β rs334558 polymorphisms might have higher penetrance of MDD. If validated in larger scale samples and in different ethnic populations, these findings might be of value as diagnostic references for MDD.

Lithium activates brain phospholipase A2 and improves memory in rats: implications for Alzheimer's disease

Phospholipase A2 (Pla2) is required for memory retrieval, and its inhibition in the hippocampus has been reported to impair memory acquisition in rats. Moreover, cognitive decline and memory deficits showed to be reduced in animal models after lithium treatment, prompting us to evaluate possible links between Pla2, lithium and memory. Here, we evaluated the possible modulation of Pla2 activity by a long-term treatment of rats with low doses of lithium and its impact in memory. Wistar rats were trained for the inhibitory avoidance task, treated with lithium for 100 days and tested for perdurability of long-term memory. Hippocampal samples were used for quantifying the expression of 19 brain-expressed Pla2 genes and for evaluating the enzymatic activity of Pla2 using group-specific radio-enzymatic assays. Our data pointed to a significant perdurability of long-term memory, which correlated with increased transcriptional and enzymatic activities of certain members of the Pla2 family (iPla2 and sPla2) after the chronic lithium treatment. Our data suggest new possible targets of lithium, add more information on its pharmacological activity and reinforce the possible use of low doses of lithium for the treatment of neurodegenerative conditions such as the Alzheimer's disease.

Mood disorders in the elderly: prevalence, functional impact, and management challenges

Despite the lower prevalence of severe mood disorders in the elderly as compared to younger adults, late-life depression and bipolar disorder (BD) are more strongly associated with negative outcomes related to the presence of medical comorbidities, cognitive deficits, and increased suicide risk and overall mortality. The mechanisms that contribute to these associations are probably multifactorial, involving pathological factors related directly and indirectly to the disease itself, ranging from biological to psychosocial factors. Most of the accumulated knowledge on the nature of these associations derives from naturalistic and observational studies, and controlled data are still scarce. Nonetheless, there has clearly been a recent growth of the scientific interest on late-life BD and geriatric depression. In the present study, we review the most relevant studies on prevalence, clinical presentation, and cognitive/functional impact of mood disorders in elderly. Several clinical-epidemiological studies were dedicated to the study of the prevalence of mood disorders in old age in distinct settings; however, fewer studies investigated the underlying neurobiological findings and treatment specificities in late-life depression and BD. In the present study, we further discuss the implications of these findings on the management of mood disorders in older adults.

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.

GSK3β Interactions with Amyloid Genes: An Autopsy Verification and Extension

Glyocogen synthase kinase 3 (GSK3) plays an important role in the pathophysiology of Alzheimer's disease (AD) through the phosphorylation of tau. Recent work has suggested that GSK3β also plays a role in the amyloid pathway of AD through genetic interactions with APP and APBB2 on in vivo measures of amyloid. This project extends the previously identified genotype interactions to an autopsy measure of amyloid, while also testing the same interactions leveraging gene expression data quantified in the prefrontal cortex. 797 participants (251 cognitively normal, 196 mild cognitive impairment, and 350 Alzheimer's disease) were drawn from the Religious Orders Study and Rush Memory and Aging Project. A mean score of amyloid load was calculated across eight brain regions, gene expression levels from frozen sections of the dorsolateral prefrontal cortex were quantified using RNA amplification, and expression signals were generated using Beadstudio. Three SNPs previously identified in genetic interactions were genotyped using the Illumina 1M genotyping chip. Covariates included age, sex, education, and diagnosis. We were able to evaluate 2 of the 3 previously identified interactions, of which the interaction between GSK3β (rs334543) and APBB2 (rs2585590) was found in this autopsy sample (p = 0.04). We observed a comparable interaction between GSK3β and APBB2 when comparing the highest tertile of gene expression to the lowest tertile, t(1) = -2.03, p = 0.043. These results provide additional evidence of a genetic interaction between GSK3β and APBB2 and further suggest that GSK3β is involved in the pathophysiology of both of the primary neuropathologies of Alzheimer's disease.

The Role of Wnt/β-Catenin Signaling Pathway in Disrupted Hippocampal Neurogenesis of Temporal Lobe Epilepsy: A Potential Therapeutic Target?

Temporal lobe epilepsy is one of the most common clinical neurological disorders. One of the major pathological findings in temporal lobe epilepsy is hippocampal sclerosis, characterized by massive neuronal loss and severe gliosis. The epileptogenesis process of temporal lobe epilepsy usually starts with initial precipitating insults, followed by neurodegeneration, abnormal hippocampus circuitry reorganization, and the formation of hypersynchronicity. Experimental and clinical evidence strongly suggests that dysfunctional neurogenesis is involved in the epileptogenesis. Recent data demonstrate that neurogenesis is induced by acute seizures or precipitating insults, whereas the capacity of neuronal recruitment and proliferation substantially decreases in the chronic phase of epilepsy. Participation of the Wnt/β-catenin signaling pathway in neurogenesis reveals its importance in epileptogenesis; its dysfunction contributes to the structural and functional abnormality of temporal lobe epilepsy, while rescuing this pathway exerts neuroprotective effects. Here, we summarize data supporting the involvement of Wnt/β-catenin signaling in the epileptogenesis of temporal lobe epilepsy. We also propose that the Wnt/β-catenin signaling pathway may serve as a promising therapeutic target for temporal lobe epilepsy treatment.

Lithium increases platelet serine-9 phosphorylated GSK-3β levels in drug-free bipolar disorder during depressive episodes

BACKGROUND

Glycogen synthase kinase-3 β (GSK3β) is an intracellular enzyme directly implicated in several neural processes relevant to bipolar disorder (BD) pathophysiology. GSK3β is also an important target for lithium and antidepressants. When phosphorylated at serine-9, GSK3β becomes inactive. Few studies evaluated serine-9 phosphorylated GSK3β (phospho-GSK3β) levels in BD subjects in vivo and no study has assessed it specifically in bipolar depression. Also, the effect of lithium monotherapy on GSK3β has never been studied in humans.

METHODS

In 27 patients with bipolar depression, total GSK3β and phospho-GSK3β were assessed in platelets by enzyme immunometric assay. Subjects were evaluated before and after 6 weeks of lithium treatment at therapeutic levels. Healthy subjects (n = 22) were used as a control group.

RESULTS

No differences in phospho-GSK3β or total GSK3β were observed when comparing drug-free BD subjects in depression and healthy controls. Baseline HAM-D scores were not correlated with phospho-GSK3β and total GSK3β levels. From baseline to endpoint, lithium treatment inactivated GSK3β by significantly increasing phospho-GSK3β levels (p = 0.010). Clinical improvement (baseline HAM-D - endpoint HAM-D) negatively correlated with the increase in phospho-GSK3β (p = 0.03).

CONCLUSION

The present results show that lithium inactivates platelet GSK3β in BD during mood episodes. No direct association with pathophysiology of BD was observed. Further studies are needed to clarify the role of GSK3β as a key biomarker in BD and its association with treatment response as well as the relevance of GSK3β in other neuropsychiatric disorders and as a new therapeutic target per se.

Toll-like receptor 4-mediated signaling participates in apoptosis of hippocampal neurons

The phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signaling pathway is considered important for cell survival and has been shown to mediate various anti-apoptotic biological effects. This study explored the role of the Toll-like receptor 4 (TLR4)-mediated PI3K/AKT-glycogen syn-thase kinase 3β (GSK-3β) signaling pathways in lipopolysaccharide-induced apoptosis in a primary culture of hippocampal neurons. Results demonstrated that the apoptotic ratio of hippocampal neurons stimulated by lipopolysaccharide was significantly higher compared with the control group. Both the expression of P-AKT^Ser473 and P-GSK-3β^Ser9 in hippocampal neurons stimulated by lipopo-polysaccharide decreased compared with the control, while the level of active Caspase-3 and the ratio of Bax/Bcl-2 were significantly increased. The level of active Caspase-3 and the ratio of Bax/Bcl-2 in hippocampal neurons treated with TLR4 antibody or the GSK-3β inhibitor, LiCl, creased before intervention with lipopolysaccharide, but increased after treatment with the AKT hibitor, LY294002. These findings suggest that the TLR4-PI3K/AKT-GSK3β signaling pathway may be involved in lipopolysaccharide-induced apoptosis of hippocampal neurons.

Neuroprotective effects of lithium: implications for the treatment of Alzheimer's disease and related neurodegenerative disorders

Lithium is a well-established therapeutic option for the acute and long-term management of bipolar disorder and major depression. More recently, based on findings from translational research, lithium has also been regarded as a neuroprotective agent and a candidate drug for disease-modification in certain neurodegenerative disorders, namely, Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and, more recently, Parkinson's disease (PD). The putative neuroprotective effects of lithium rely on the fact that it modulates several homeostatic mechanisms involved in neurotrophic response, autophagy, oxidative stress, inflammation, and mitochondrial function. Such a wide range of intracellular responses may be secondary to two key effects, that is, the inhibition of glycogen synthase kinase-3 beta (GSK-3β) and inositol monophosphatase (IMP) by lithium. In the present review, we revisit the neurobiological properties of lithium in light of the available evidence of its neurotrophic and neuroprotective properties, and discuss the rationale for its use in the treatment and prevention of neurodegenerative diseases.

Lithium chloride alleviates neurodegeneration partly by inhibiting activity of GSK3β in a SCA3 Drosophila model

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by the expansion of a CAG trinucelotide repeat that encodes an abnormal polyglutamine (PolyQ) tract in the disease protein, ataxin-3. The formation of neuronal intranuclear inclusions in the specific brain regions is one of the pathological hallmarks of SCA3. Acceleration of the degradation of the mutant protein aggregates is proven to produce beneficial effects in SCA3 and other PolyQ diseases. Lithium is known to be neuroprotective in various models of neurodegenerative disease and can reduce the mutant protein aggregates by inducing autophagy. In this study, we explored the therapeutic potential of lithium in a SCA3 Drosophila model. We showed that chronic treatment with lithium chloride at specific doses notably prevented eye depigmentation, alleviated locomotor disability, and extended the median life spans of SCA3 transgenic Drosophila. By means of genetic approaches, we showed that co-expressing the mutant S9E, which mimicked the phosphorylated S9 state of Shaggy as done by lithium, also partly decreased toxicity of gmr-SCA3tr-Q78. Taken together, our findings suggest that lithium is a promising therapeutic agent for the treatment of SCA3 and other PolyQ diseases.

Dysfunctional Wnt/β-catenin signaling contributes to blood-brain barrier breakdown in Alzheimer's disease

Increased Aβ clearance from brain is essential for restoring the pathological manifestation of Alzheimer's disease (AD) and attenuating the cognitive disorder. The blood-brain barrier (BBB) plays a critical role in maintaining homeostasis of the brain, and transporters e.g. P-glycoprotein (P-gp) are essential for Aβ clearance from the brain. In addition, the Wnt/β-catenin signaling pathway contributes to BBB formation, induction and maturation, and induces BBB function. Dysfunctional Wnt/β-catenin signaling in the BBB reveals the importance of this pathway, since this contributes to the neurodegeneration characteristic of AD. Based on the above evidence, we propose that targeting the canonical Wnt signaling pathway could be promising therapeutic approach for treatment of AD.

Alzheimer's disease, enzyme targets and drug discovery struggles: from natural products to drug prototypes

Alzheimer's disease (AD) is an incapacitating neurodegenerative disease that slowly destroys brain cells. This disease progressively compromises both memory and cognition, culminating in a state of full dependence and dementia. Currently, AD is the main cause of dementia in the elderly and its prevalence in the developed world is increasing rapidly. Classic drugs, such as acetylcholinesterase inhibitors (AChEIs), fail to decline disease progression and display several side effects that reduce patient's adhesion to pharmacotherapy. The past decade has witnessed an increasing focus on the search for novel AChEIs and new putative enzymatic targets for AD, like β- and γ-secretases, sirtuins, caspase proteins and glycogen synthase kinase-3 (GSK-3). In addition, new mechanistic rationales for drug discovery in AD that include autophagy and synaptogenesis have been discovered. Herein, we describe the state-of-the-art of the development of recent enzymatic inhibitors and enhancers with therapeutic potential on the treatment of AD.

Role of lithium augmentation in the management of major depressive disorder

The high rate of non-responders to initial treatment with antidepressants requires subsequent treatment strategies such as augmentation of antidepressants. Clinical guidelines recommend lithium augmentation as a first-line treatment strategy for non-responding depressed patients. The objectives of this review were to discuss the current place of lithium augmentation in the management of treatment-resistant depression and to review novel findings concerning lithium's mechanisms of action. We conducted a comprehensive and critical review of randomized, placebo-controlled trials, controlled and naturalistic comparator studies, and continuation-phase and discontinuation studies of lithium augmentation in major depression. The outcomes of interest were efficacy, factors allowing outcome prediction and results from preclinical studies investigating molecular mechanisms of lithium action. Substantial efficacy of lithium augmentation in the acute treatment of major depression has been demonstrated in more than 30 open-label studies and 10 placebo-controlled trials. In a meta-analysis addressing the efficacy of lithium in 10 randomized, controlled trials, it had a significant positive effect versus placebo, with an odds ratio of 3.11 corresponding to a number-needed-to-treat (NNT) of 5 and a mean response rate of 41.2% (versus 14.4% in the placebo group). The main limitations of these studies were the relatively small numbers of study participants and the fact that most studies included augmentation of tricyclic antidepressants, which are not in widespread use anymore. Evidence from continuation-phase studies is sparse but suggests that lithium augmentation should be maintained in the lithium-antidepressant combination for at least 1 year to prevent early relapses. Concerning outcome prediction, single studies have reported associations of better outcome rates with more severe depressive symptomatology, significant weight loss, psychomotor retardation, a history of more than three major depressive episodes and a family history of major depression. Additionally, one study suggested a predictive role of the -50T/C single nucleotide polymorphism of the glycogen synthase kinase 3 beta (GSK3B) gene in the probability of response to lithium augmentation. With regard to novel mechanisms of action, GABAergic, neurotrophic and genetic effects might explain the effects of lithium augmentation. In conclusion, augmentation of antidepressants with lithium remains a first-line, evidence-based management option for patients with major depression who have not responded adequately to antidepressants. While the mechanisms of action are currently widely studied, further clinical research on the role of lithium potentiation of the current generation of antidepressants is warranted to reinforce its role as a gold-standard treatment for patients who respond inadequately to antidepressants.

GSK-3/CREB pathway involved in the gx-50's effect on Alzheimer's disease

Aggregation of amyloid-beta (Aβ) fragments is one of the major pathological hallmarks of Alzheimer's disease (AD). Our previous study has demonstrated that a novel compound named N-[2-(3, 4-dimethoxyphenyl) ethyl]-3-phenyl-acrylamide (gx-50) can decrease the accumulation of Aβ oligomers in the cerebral cortex and improve the cognitive abilities in transgenic demented mice. To further study the mechanism of the neuroprotective effect of gx-50 against AD, we employed microarray to investigate the gene expression profile of the primary cultured neurons treated with gx-50 or/and Aβ. Microarray disclosed 351 genes associated with AD in the gx-50 plus Aβ treated group, out of the 22,523 probes. 217 of the 351 genes were significantly up-regulated, 134 of them were down-regulated. The 351 genes were mainly involved in neurotransmission, signal transduction, nervous system development, protein phosphorylation, transcription and apoptosis. By the Onto-pathway analysis, a network involved two molecules - GSK-3, CREB and another two closely linked proteins - AKT, BDNF was discovered. The GSK/CREB pathway was further studied at the gene and protein level both in vivo and in vitro. Western blot and immunohistochemistry analysis showed that the gx-50 elevated the AKT phosphorylation and inhibited its downstream protein - GSK-3's activity, then restored the CREB's transcriptional activity, and finally enhanced the expression of the CREB target gene - BDNF. In addition, the real-time PCR results displayed the same tendency. In conclusion, studies in this research indicated that the gx-50 may improve the cognitive ability of AD via the GSK-3/CREB pathway.

Lithium: the pharmacodynamic actions of the amazing ion

Lithium has been used for the treatment of mood disorders for over 60 years, yet the exact mechanisms by which it exerts its therapeutic effects remain unclear. Two enzymatic chains or pathways emerge as targets for lithium: inositol monophosphatase within the phosphatidylinositol signalling pathway and the protein kinase glycogen synthase kinase 3. Lithium inhibits these enzymes through displacing the normal cofactor magnesium, a vital regulator of numerous signalling pathways. Here we provide an overview of evidence, supporting a role for the inhibition of glycogen synthase kinase 3 and inositol monophosphatase in the pharmacodynamic actions of lithium. We also explore how inhibition of these enzymes by lithium can lead to downstream effects of clinical relevance, both for mood disorders and neurodegenerative diseases. Establishing a better understanding of lithium's mechanisms of action may allow the development of more effective and more tolerable pharmacological agents for the treatment of a range of mental illnesses, and provide clearer insight into the pathophysiology of such disorders.