Glycogen synthase kinase-3: a putative molecular target for lithium mimetic drugs

Involvement of PI3K/Akt/GSK-3β and mTOR in the antidepressant-like effect of atorvastatin in mice

Atorvastatin is a cholesterol-lowering statin that has been shown to exert several pleiotropic effects in the nervous system as a neuroprotective and antidepressant-like agent. Antidepressant-like effect of atorvastatin in mice is mediated by glutamatergic and serotoninergic receptors, although the precise intracellular signaling pathways involved are unknown. PI3K/Akt/GSK-3β/mTOR signaling pathway has been associated to neurobiology of depression and seems to be modulated by some pharmacological antidepressant strategies. The present study investigated the participation of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of an acute atorvastatin treatment in mice. Atorvastatin sub-effective (0.01 mg/kg) or effective (0.1 mg/kg) doses in the tail suspension test (TST) was administered orally alone or in combination with PI3K, GSK-3β or mTOR inhibitors. The administration of PI3K inhibitor, LY294002 (10 nmol/site, i.c.v) completely prevented the antidepressant-like effect of atorvastatin (0.1 mg/kg, p.o.). The participation of GSK-3β in the antidepressant-like effect of atorvastatin was demonstrated by co-administration of a sub-effective dose of atorvastatin (0.01 mg/kg, p.o.) with AR-A014418 (0.01 μg/site, i.c.v., a selective GSK-3β inhibitor) or with lithium chloride (10 mg/kg, p.o., a non-selective GSK-3β inhibitor). The mTOR inhibitor, rapamycin (0.2 nmol/site, i.c.v.) was also able to prevent atorvastatin (0.1 mg/kg, p.o.) antidepressant-like effect. These behavioral findings were supported by neurochemical observations, as atorvastatin treatment increased the immunocontent of the phosphorylated isoforms of Akt, GSK-3β and mTOR in the hippocampus of mice. Taken together, our results suggest an involvement of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of atorvastatin in mice.

Amyloid beta modulators and neuroprotection in Alzheimer's disease: a critical appraisal

Multiple cellular changes have been identified as being involved in Alzheimer's disease (AD) pathogenesis, including mitochondrial damage, synaptic loss, amyloid beta (Aβ) production and/or accumulation, inflammatory responses, and phosphorylated tau formation and/or accumulation. Studies have established that Aβ-induced synaptic dysfunction is dependent on abnormal amyloid precursor protein (APP) processing caused by β- and γ-secretases, resulting in the generation of Aβ. The Aβ formed as a result of abnormal APP processing induces phosphorylated tau and activates glycogen synthase kinase-3β (GSK3β) and cyclin-dependent kinase-5 (CDK5). Here, we review the latest research on the development of Aβ modulators for neuroprotection in AD. We also review the use of molecular inhibitors as therapeutic targets in AD.

Prevalence of Circadian Rhythm Sleep-Wake Disorders and Associated Factors in Euthymic Patients with Bipolar Disorder

Recent studies have suggested that there are certain pathophysiological relationships between bipolar disorder (BD) and circadian rhythm dysfunction. However, apparently no studies have clarified the prevalence of circadian rhythm sleep-wake disorders (CRSWD) in patients with BD. This study was set out to investigate the prevalence of CRSWD and associated factors in patients with BD. One hundred four euthymic BD outpatients participated in this study. The subjects were asked to answer questionnaires including demographic variables, clinical course of BD, and family history of psychiatric disorders and suicide. Severity of BD was assessed by the Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. CRSWD was diagnosed by clinical interview, together with sleep logs, according to the International Classification of Sleep Disorders, third edition (ICSD-3). Thirty-five subjects (32.4%) met the criteria for CRSWD. The age at the time of investigation and that at the onset of BD were both lower in the CRSWD group than in the non-CRSWD group. The rates of family history of psychiatric disorders and suicide in the CRSWD group were higher than those in the non-CRSWD group. Multiple logistic regression analysis revealed that the presence of CRSWD was significantly associated with younger onset age of BD and family history of suicide. The prevalence of CRSWD could be quite high in BD patients. Younger onset age of BD and family history of suicide were associated with presence of CRSWD in BD patients.

Molecular Signatures of Psychosocial Stress and Cognition Are Modulated by Chronic Lithium Treatment

Chronic psychosocial stress is an important environmental risk factor of psychiatric diseases such as schizophrenia. Social defeat in rodents has been shown to be associated with maladaptive cellular and behavioral consequences including cognitive impairments. Although gene expression changes upon psychosocial stress have been described, a comprehensive transcriptome profiling study at the global level in precisely defined hippocampal subregions which are associated with learning has been lacking. In this study, we exposed adult C57Bl/6N mice for 3 weeks to "resident-intruder" paradigm and combined laser capture microdissection with microarray analyses to identify transcriptomic signatures of chronic psychosocial stress in dentate gyrus and CA3 subregion of the dorsal hippocampus. At the individual transcript level, we detected subregion specific stress responses whereas gene set enrichment analyses (GSEA) identified several common pathways upregulated upon chronic psychosocial stress related to proteasomal function and energy supply. Behavioral profiling revealed stress-associated impairments most prominent in fear memory formation which was prevented by chronic lithium treatment. Thus, we again microdissected the CA3 region and performed global transcriptome analysis to search for molecular signatures altered by lithium treatment in stressed animals. By combining GSEA with unsupervised clustering, we detected pathways that are regulated by stress and lithium in the CA3 region of the hippocampus including proteasomal components, oxidative phosphorylation, and anti-oxidative mechanisms. Our study thus provides insight into hidden molecular phenotypes of chronic psychosocial stress and lithium treatment and proves a beneficial role for lithium treatment as an agent attenuating negative effects of psychosocial stress on cognition.

Multiple Drug Treatments That Increase cAMP Signaling Restore Long-Term Memory and Aberrant Signaling in Fragile X Syndrome Models

Fragile X is the most common monogenic disorder associated with intellectual disability (ID) and autism spectrum disorders (ASD). Additionally, many patients are afflicted with executive dysfunction, ADHD, seizure disorder and sleep disturbances. Fragile X is caused by loss of FMRP expression, which is encoded by the FMR1 gene. Both the fly and mouse models of fragile X are also based on having no functional protein expression of their respective FMR1 homologs. The fly model displays well defined cognitive impairments and structural brain defects and the mouse model, although having subtle behavioral defects, has robust electrophysiological phenotypes and provides a tool to do extensive biochemical analysis of select brain regions. Decreased cAMP signaling has been observed in samples from the fly and mouse models of fragile X as well as in samples derived from human patients. Indeed, we have previously demonstrated that strategies that increase cAMP signaling can rescue short term memory in the fly model and restore DHPG induced mGluR mediated long term depression (LTD) in the hippocampus to proper levels in the mouse model (McBride et al., 2005; Choi et al., 2011, 2015). Here, we demonstrate that the same three strategies used previously with the potential to be used clinically, lithium treatment, PDE-4 inhibitor treatment or mGluR antagonist treatment can rescue long term memory in the fly model and alter the cAMP signaling pathway in the hippocampus of the mouse model.

A differential impact of lithium on endothelium-dependent but not on endothelium-independent vessel relaxation

Lithium is drug for bipolar disorders with a narrow therapeutic window. Lithium was recently reported to prevent stroke and protect vascular endothelium but tends to accumulate particularly in the brain and kidney. Here, adverse effects are common; however mechanisms are still vaguely understood. If lithium could also negatively influence the endothelium is unclear. We hypothesize that at higher lithium levels, the effects on endothelium reverses--that lithium also impairs endothelial-dependent relaxation of blood vessels. Vessel grafts from de-nerved murine aortas and porcine middle cerebral arteries were preconditioned using media supplemented with lithium chloride or acetate (0.4-100 mmol/L). Native or following phenylephrine-induced vasoconstriction, the relaxation capacity of preconditioned vessels was assessed by isometric myography, using acetylcholine to test the endothelium-dependent or sodium nitroprusside to test the endothelium-independent vasorelaxation, respectively. At the 0.4 mmol/L lithium concentration, acetylcholine-induced endothelium-dependent vessel relaxation was slightly increased, however, diminished in a concentration-dependent manner in vessel grafts preconditioned with lithium at higher therapeutic and supratherapeutic concentrations (0.8-100 mmol/L). In contrast, endothelium-independent vasorelaxation remained unaltered in preconditioned vessel grafts at any lithium concentration tested. Lithium elicits opposing effects on endothelial functions representing a differential impact on the endothelium within the narrow therapeutic window. Lithium accumulation or overdose reduces endothelium-dependent but not endothelium-independent vasorelaxation. The differentially modified endothelium-dependent vascular response represents an additional mechanism contributing to therapeutic or adverse effects of lithium.

Inhibition of Glycogen Synthase Kinase-3: An Emerging Target in the Treatment of Traumatic Brain Injury

Although traumatic brain injury (TBI) has been a major public health concern for decades, the pathophysiological mechanism of TBI is not clearly understood, and an effective medical treatment of TBI is not available at present. Of particular concern is sustained TBI, which has a strong tendency to take a deteriorating neurodegenerative course into chronic traumatic encephalopathy (CTE) and dementia, including Alzheimer's disease. Tauopathy and beta amyloid (Aβ) plaques are known to be the key pathological markers of TBI, which contribute to the progressive deterioration associated with TBI such as CTE and Alzheimer's disease. The multiple lines of evidence strongly suggest that the inhibition of glycogen synthase kinase-3 (GSK-3) is a potential target in the treatment of TBI. GSK-3 constitutively inhibits neuroprotective processes and promotes apoptosis. After TBI, GSK-3 is inhibited through the receptor tyrosine kinase (RTK) and canonical Wnt signaling pathways as an innate neuroprotective mechanism against TBI. GSK-3 inhibition via GSK-3 inhibitors and drugs activating RTK or Wnt signaling is likely to reinforce the innate neuroprotective mechanism. GSK-3 inhibition studies using rodent TBI models demonstrate that GSK-3 inhibition produces diverse neuroprotective actions such as reducing the size of the traumatic injury, tauopathy, Aβ accumulation, and neuronal death, by releasing and activating neuroprotective substrates from GSK-3 inhibition. These effects are correlated with reduced TBI-induced behavioral and cognitive symptoms. Here, we review studies on the therapeutic effects of GSK-3 inhibition in TBI rodent models, and critically discuss the issues that these studies address.

Animal models of bipolar mania: The past, present and future

Bipolar disorder (BD) is the sixth leading cause of disability in the world according to the World Health Organization and affects nearly six million (∼2.5% of the population) adults in the United State alone each year. BD is primarily characterized by mood cycling of depressive (e.g., helplessness, reduced energy and activity, and anhedonia) and manic (e.g., increased energy and hyperactivity, reduced need for sleep, impulsivity, reduced anxiety and depression), episodes. The following review describes several animal models of bipolar mania with a focus on more recent findings using genetically modified mice, including several with the potential of investigating the mechanisms underlying 'mood' cycling (or behavioral switching in rodents). We discuss whether each of these models satisfy criteria of validity (i.e., face, predictive, and construct), while highlighting their strengths and limitations. Animal models are helping to address critical questions related to pathophysiology of bipolar mania, in an effort to more clearly define necessary targets of first-line medications, lithium and valproic acid, and to discover novel mechanisms with the hope of developing more effective therapeutics. Future studies will leverage new technologies and strategies for integrating animal and human data to reveal important insights into the etiology, pathophysiology, and treatment of BD.

FKBP51 inhibits GSK3β and augments the effects of distinct psychotropic medications

Psychotropic medications target glycogen synthase kinase 3β (GSK3β), but the functional integration with other factors relevant for drug efficacy is poorly understood. We discovered that the suggested psychiatric risk factor FK506 binding protein 51 (FKBP51) increases phosphorylation of GSK3β at serine 9 (pGSK3β(S9)). FKBP51 associates with GSK3β mainly through its FK1 domain; furthermore, it also changes GSK3β's heterocomplex assembly by associating with the phosphatase PP2A and the kinase cyclin-dependent kinase 5. FKBP51 acts through GSK3β on the downstream targets Tau, β-catenin and T-cell factor/lymphoid enhancing factor (TCF/LEF). Lithium and the antidepressant (AD) paroxetine (PAR) functionally synergize with FKBP51, as revealed by reporter gene and protein association analyses. Deletion of FKBP51 blunted the PAR- or lithium-induced increase in pGSK3β(S9) in cells and mice and attenuated the behavioral effects of lithium treatment. Clinical improvement in depressive patients was predicted by baseline GSK3β pathway activity and by pGSK3β(S9) reactivity to ex vivo treatment of peripheral blood mononuclear lymphocytes with lithium or PAR. In sum, FKBP51-directed GSK3β activity contributes to the action of psychotropic medications. Components of the FKBP51-GSK3β pathway may be useful as biomarkers predicting AD response and as targets for the development of novel ADs.

Role of the Wnt/β-catenin signaling pathway in the response of chondrocytes to mechanical loading

In order to better understand the mechanisms by which chondrocytes respond to mechanical stimulation, ATDC5 mouse embryonic carcinoma cells were induced to differentiate into chondrocytes and then exposed to mechanical loading. To specifically elucidate the role of this pathway, the localization and expression of proteins involved in the Wnt/β-catenin signaling pathway were observed. Chondrogenic-differentiated ATDC5 cells were exposed to a 12% cycle tension load for 1, 2, 4, or 8 h. At each time point, immunofluorescence staining, western blot analysis, and qPCR were used to track the localization of β-catenin and glycogen synthase kinase-3β (GSK-3β) expression. In addition, the mRNA expression of Wnt3a, disheveled homolog 1 (Dvl-1), GSK-3β, and collagen type II were also detected. Activation of the Wnt/β-catenin signaling pathway was investigated in cells treated with Dickkopf-related protein 1 (DKK-1). β-catenin and GSK-3β protein expression increased initially and then decreased over the mechanical loading period, and the corresponding mRNA levels followed a similar trend. After application of the inhibitor DKK-1, Wnt/β‑catenin signaling was suppressed, and the mRNA expression of collagen II was also reduced. Thus, stimulation of chondrocytes with mechanical strain loading is associated with the translocation of active β-catenin from the cytoplasm to the nucleus.

Decreased serum zinc concentration during depressive episode in patients with bipolar disorder

OBJECTIVES

Zinc may be involved in the pathophysiology and treatment of depressive disorder. However, data on this issue in bipolar disorder (BD) are limited. The aim of the study was to assess zinc concentrations in the blood serum of patients at various phases and stages of bipolar disorder.

METHODS

The study included 129 patients with a diagnosis of bipolar disorder type I (n=69) or type II (n=60). Fifty-eight were in a depressive episode, 23 in a manic episode and 48 in remission. Fifty healthy volunteers made a control group. Zinc concentration was measured using flame atomic absorption spectrometry.

RESULTS

Serum zinc level in patients diagnosed with BD type I in the depressive phase was significantly reduced as compared with mania, remission and healthy subjects. In the BD type II, serum zinc level in hypomania, depression or remission phase was not significantly different from the control group. In the whole group, lower level of zinc in depression compared to remission and control subjects was found during late stage of the illness but not in the early stage. Zinc concentration was not dependent on the severity of manic or depressive symptoms and subtype of depression but correlated positively with the number of manic/hypomanic relapses in the past year.

LIMITATIONS

Lack of prospective model, heterogeneity of pharmacological treatment, small number of subgroups presenting specified clinical features.

CONCLUSIONS

Decreased serum zinc concentration occurs in depression in BD type I and probably in depression in the late stage of BD.

Obesity and Its Potential Effects on Antidepressant Treatment Outcomes in Patients with Depressive Disorders: A Literature Review

Accumulating evidence regarding clinical, neurobiological, genetic, and environmental factors suggests a bidirectional link between obesity and depressive disorders. Although a few studies have investigated the link between obesity/excess body weight and the response to antidepressants in depressive disorders, the effect of weight on treatment response remains poorly understood. In this review, we summarized recent data regarding the relationship between the response to antidepressants and obesity/excess body weight in clinical studies of patients with depressive disorders. Although several studies indicated an association between obesity/excess body weight and poor antidepressant responses, it is difficult to draw definitive conclusions due to the variability of subject composition and methodological differences among studies. Especially, differences in sex, age and menopausal status, depressive symptom subtypes, and antidepressants administered may have caused inconsistencies in the results among studies. The relationship between obesity/excess body weight and antidepressant responses should be investigated further in high-powered studies addressing the differential effects on subject characteristics and treatment. Moreover, future research should focus on the roles of mediating factors, such as inflammatory markers and neurocognitive performance, which may alter the antidepressant treatment outcome in patients with comorbid obesity and depressive disorder.

Norepinephrine versus dopamine and their interaction in modulating synaptic function in the prefrontal cortex

Among the neuromodulators that regulate prefrontal cortical circuit function, the catecholamine transmitters norepinephrine (NE) and dopamine (DA) stand out as powerful players in working memory and attention. Perturbation of either NE or DA signaling is implicated in the pathogenesis of several neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), schizophrenia, and drug addiction. Although the precise mechanisms employed by NE and DA to cooperatively control prefrontal functions are not fully understood, emerging research indicates that both transmitters regulate electrical and biochemical aspects of neuronal function by modulating convergent ionic and synaptic signaling in the prefrontal cortex (PFC). This review summarizes previous studies that investigated the effects of both NE and DA on excitatory and inhibitory transmissions in the prefrontal cortical circuitry. Specifically, we focus on the functional interaction between NE and DA in prefrontal cortical local circuitry, synaptic integration, signaling pathways, and receptor properties. Although it is clear that both NE and DA innervate the PFC extensively and modulate synaptic function by activating distinctly different receptor subtypes and signaling pathways, it remains unclear how these two systems coordinate their actions to optimize PFC function for appropriate behavior. Throughout this review, we provide perspectives and highlight several critical topics for future studies. This article is part of a Special Issue entitled SI: Noradrenergic System.

Investigations on GSK-3β/NF-kB signaling in stress and stress adaptive behavior in electric foot shock subjected mice

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice.

Renal microcysts and lithium

OBJECTIVE

To review the relationship between lithium-related renal dysfunction and microcysts.

METHOD

Electronic databases (PubMed and Google Scholar) were queried.

RESULTS

From a total of 12,425 publications, 76 were reviewed.

DISCUSSION

Glomerular renal dysfunction occurs after an average of 20 years of continuous lithium treatment, and the severity is related to the total lithium load as measured by dose and duration. Recently, several reports have highlighted the relationship between renal microcyst formation and significant reductions in glomerular filtration rate. Radiologically visible lithium-related microcysts are usually 1-2 mm and occasionally 3 mm. Smaller cysts, which are impossible to resolve, are probably more common than the visible cysts, based on observations of renal needle biopsies. Increases in the number of microcysts and the space they occupy within kidney volume appear to be related to both the duration of lithium treatment and the reduction in kidney function. The proposed mechanism of microcyst formation is related to the antiapoptotic effect of lithium. Specifically, by preventing renal tubular epithelial cells from undergoing apoptosis as part of the process of normal renal maintenance, lithium may be allowing the inappropriate growth of the surface area of tubules to form invaginations and ultimately cysts. It is proposed that the physical space occupied by these cysts in the limited volume within the renal capsule compromises the function of otherwise healthy renal tissue. Monitoring of kidneys utilizing radiographic imaging may be more sensitive than monitoring laboratory values. Additional research is required to optimize this new monitoring tool.

Cardioprotection of ginsenoside Rb1 against ischemia/reperfusion injury is associated with mitochondrial permeability transition pore opening inhibition

OBJECTIVE

To investigate the role of ginsenoside Rb1 (Gs-Rb1) in cardioprotection against ischemia/reperfusion (I/R) or hypoxia/reoxygenation (H/R) injury and to explore whether the cardioprotective action is mediated via attenuating the formation of mitochondrial permeability transition pore (mPTP).

METHODS

A Langendorff-perfused model of rat heart was employed. I/R injury was induced by breaking off perfusion for 40 min then reperfusion for 60 min. Gs-Rb1 (100 μmol/L) were administrated for 10 min before I/R. Infarct size was estimated by the 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Lactate dehydrogenase (LDH) and creatine kinase (CK) released from effluents were measured. Transmission electron microscopy was performed to assess morphological difference between cardiac mitochondrial isolated from I/R rats and Gs-Rb1 pretreated rats. Western blot analysis was used to determine phosphorylation of protein kinase B/Akt, and its downstream target glycogen synthase kinase 3β (GSK-3β). Incubation isolated cardiac mitochondria with Gs-Rb1, Ca2+-induced opening of the mPTP was assessed by the reduction of absorbance at 520 nm (A520). Neonatal rat cardiomyocytes were subjected to hypoxia 9 h followed by reoxygenation 4 h to induce H/R injury. After pretreated with different concentration of Gs-Rb1 (6.25, 25, 100 μmol/L ), cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) method. The membrane potential was estimated by Rh123 fluorescence. mPTP opening was measured using the probe calcein-AM.

RESULTS

Gs-Rb1 100 μmol/L significantly reduced the infarct size of hearts (26.39%±11.67% vs. I/R group 56.68%±5.88%, P<0.01). Compared with the I/R group, Gs-Rb1 pretreatment decreased LDH and CK levels in the coronary effluent (P<0.05 or P<0.01) as well as attenuated destructive ultrastructure induced by I/R. The protective effect of Gs-Rb1 involved in phosphorylating protein kinase B/PKB (Akt) and GSK-3β. In mitochondria isolated from rat hearts, significant inhibition of Ca2+-induced swelling was observed in samples that were pretreated with Gs-Rb1 (6.25, 25, 100, 400 μmol/L) for 10 min. When cardiomyocytes were isolated from neonatal rat and subjected to H/R, cell viability was increased with treatment of Gs-Rb1 (6.25, 25, 100 μmol/L ). Gs-Rb1 inhibited mPTP opening and restored subsequent loss of mitochondrial membrane potential.

CONCLUSION

Gs-Rb1 presents cardioprotective effect against I/R or H/R injury which involves in activating Akt, phosphorylating GSK-3β and inhibiting mPTP opening.

Functional Implications of the CLOCK 3111T/C Single-Nucleotide Polymorphism

Circadian rhythm disruptions are prominently associated with bipolar disorder (BD). Circadian rhythms are regulated by the molecular clock, a family of proteins that function together in a transcriptional-translational feedback loop. The CLOCK protein is a key transcription factor of this feedback loop, and previous studies have found that manipulations of the Clock gene are sufficient to produce manic-like behavior in mice (1). The CLOCK 3111T/C single-nucleotide polymorphism (SNP; rs1801260) is a genetic variation of the human CLOCK gene that is significantly associated with increased frequency of manic episodes in BD patients (2). The 3111T/C SNP is located in the 3'-untranslated region of the CLOCK gene. In this study, we sought to examine the functional implications of the human CLOCK 3111T/C SNP by transfecting a mammalian cell line (mouse embryonic fibroblasts isolated from Clock(-/-) knockout mice) with pcDNA plasmids containing the human CLOCK gene with either the T or C SNP at position 3111. We then measured circadian gene expression over a 24-h time period. We found that the CLOCK3111C SNP resulted in higher mRNA levels than the CLOCK 3111T SNP. Furthermore, we found that Per2, a transcriptional target of CLOCK, was also more highly expressed with CLOCK 3111C expression, indicating that the 3'-UTR SNP affects the expression, function, and stability of CLOCK mRNA.

Diabetes-associated depression: the serotonergic system as a novel multifunctional target

Diabetes associated depression is a largely understudied field which nonetheless carries a significant disease burden. The very low therapeutic efficacy of the existing conventional drugs with poor outcome may be, in part, due to uncertainty of the mechanism involved that clearly explains the existing comorbidity. The main purpose of this review was to address the sophisticated mechanisms of this comorbidity with a view of developing potential novel targets with higher efficacy and specificity. Data were collected from database searches including PubMed, references from relevant English language research/review articles and other official publications. Articles from 1990 to 2013 were included, and a broad search term criteria were followed for data mining so that relevant information was not missed out. Some of the search terms used included; diabetes-induced depression, diabetes and serotonin, hypothalamic-pituitary-adrenal (HPA) axis and diabetes and glucocorticoids in diabetes. Neuropathologically, depletion of brain monoaminergic activity specifically the serotonin (5-hydroxytryptamine [5-HT]) system, due to chronically persisting diabetic state may lead to the mood and behavioral complications that further add on worsening the quality life years. The 5-HT system through multifunctional tasks regulates neurogenesis and plasticity and by complex receptor mechanism controls the emotional and behavioral activity. Persisting hyperglycemia leads to impaired neurogenesis, decreased synaptic plasticity, undesired neuro-anatomical alterations, neurochemical deficits, and reduced neurotransmitter activity. The neurotrophic factors and secondary messenger functions affected at molecular and genetic levels indicate the impact of diabetes-mediated dysregulation on neuronal circuits. HPA activity, glycogen synthase kinase 3, and insulin signaling controls were also found to be hampered, interlinked to 5-HT system following diabetic progression.

Increased iPLA2 activity and levels of phosphorylated GSK3B in platelets are associated with donepezil treatment in Alzheimer's disease patients

Reduced phospholipase A2 (PLA2) activity and increased phosphorylation of glycogen synthase kinase 3B (GSK3B) participate in the production of beta-amyloid plaques and of neurofibrillary tangles, which are two neuropathological hallmarks of Alzheimer's disease (AD). Experimental evidences suggest a neuroprotective effect of the cholinesterase inhibitor donepezil in the treatment the disease. The aims of the present study were to evaluate in AD patients the effects of treatment with donepezil on PLA2 activity and GSK3B level. Thirty patients with AD were treated during 6 months with 10 mg daily of donepezil. Radio-enzymatic assays were used to measure PLA2 activity and Elisa assays for GSK3B level, both in platelets. Before treatment and after 3 and 6 months on donepezil, AD patients underwent a cognitive assessment and platelet samples were collected. Values were compared to a healthy control group of 42 sex- and age-matched elderly individuals. Before treatment, iPLA2 activity was lower in patients with AD as compared to controls (p < 0.001). At baseline, no differences were found in GSK3B level between both groups. After 3 and 6 months of treatment, we found a significant increase in iPLA2 activity (p = 0.015 and p < 0.001, respectively). iPLA2 increment was related to the cognitive improvement during treatment (p = 0.037). After 6 months, we found an increase in phosphorylated GSK3B (p = 0.02). The present findings suggest two possible mechanisms by which donepezil delays the progression of AD. The increment of iPLA2 activity may reduce the production of beta-amyloid plaques, whereas the phosphorylation of GSK3B inactivates the enzyme, reducing thus the phosphorylation of tau protein.

Antimanic-like activity of candesartan in mice: Possible involvement of antioxidant, anti-inflammatory and neurotrophic mechanisms

Activation of the brain angiotensin II type 1 receptor (AT1R) triggers pro-oxidant and pro-inflammatory mechanisms which are involved in the neurobiology of bipolar disorder (BD). Candesartan (CDS) is an AT1 receptor antagonist with potential neuroprotective properties. Herein we investigated CDS effects against oxidative, neurotrophic inflammatory and cognitive effects of amphetamine (AMPH)-induced mania. In the reversal protocol adult mice were given AMPH 2 mg/kg i.p. or saline and between days 8 and 14 received CDS 0.1, 0.3 or 1 mg/kg orally, lithium (Li) 47.5 mg/kg i.p., or saline. In the prevention treatment, mice were pretreated with CDS, Li or saline prior to AMPH. Locomotor activity and working memory performance were assessed. Glutathione (GSH), thiobarbituric acid-reactive substance (TBARS) and TNF-α levels were evaluated in the hippocampus (HC) and cerebellar vermis (CV). Brain-derived neurotrophic factor (BDNF) and glycogen synthase kinase 3-beta (GSK-3beta) levels were measured in the HC. CDS and Li prevented and reversed the AMPH-induced increases in locomotor activity. Only CDS prevented and reversed AMPH-induced working memory deficits. CDS prevented AMPH-induced alterations in GSH (HC and CV), TBARS (HC and CV), TNF-α (HC and CV) and BDNF (HC) levels. Li prevented alterations in BDNF and phospho-Ser9-GSK3beta. CDS reversed AMPH-induced alterations in GSH (HC and CV), TBARS (HC), TNF-α (CV) and BDNF levels. Li reversed AMPH-induced alterations in TNF-α (HC and CV) and BDNF (HC) levels. CDS is effective in reversing and preventing AMPH-induced behavioral and biochemical alterations, providing a rationale for the design of clinical trials investigating CDS׳s possible therapeutic effects.

Potential application of lithium in Parkinson's and other neurodegenerative diseases

Lithium, the long-standing hallmark treatment for bipolar disorder, has recently been identified as a potential neuroprotective agent in neurodegeneration. Here we focus on introducing numerous in vitro and in vivo studies that have shown lithium treatment to be efficacious in reducing oxidative stress and inflammation, increasing autophagy, inhibiting apoptosis, and decreasing the accumulation of α-synulcein, with an emphasis on Parkinson's disease. A number of biological pathways have been shown to be involved in causing these neuroprotective effects. The inhibition of GSK-3β has been the mechanism most studied; however, other modes of action include the regulation of apoptotic proteins and glutamate excitotoxicity as well as down-regulation of calpain. This review provides a framework of the neuroprotective effects of lithium in neurodegenerative diseases and the putative mechanisms by which lithium provides the protection. Lithium-only treatment may not be a suitable therapeutic option for neurodegenerative diseases due to inconsistent efficacy and potential side-effects, however, the use of low dose lithium in combination with other potential or existing therapeutic compounds may be a promising approach to reduce symptoms and disease progression in neurodegenerative diseases.

Pivotal role of glycogen synthase kinase-3: A therapeutic target for Alzheimer's disease

Neurodegenerative diseases are among the most challenging diseases with poorly known mechanism of cause and paucity of complete cure. Out of all the neurodegenerative diseases, Alzheimer's disease is the most devastating and loosening of thinking and judging ability disease that occurs in the old age people. Many hypotheses came forth in order to explain its causes. In this review, we have enlightened Glycogen Synthase Kinase-3 which has been considered as a concrete cause for Alzheimer's disease. Plaques and Tangles (abnormal structures) are the basic suspects in damaging and killing of nerve cells wherein Glycogen Synthase Kinase-3 has a key role in the formation of these fatal accumulations. Various Glycogen Synthase Kinase-3 inhibitors have been reported to reduce the amount of amyloid-beta as well as the tau hyperphosphorylation in both neuronal and nonneuronal cells. Additionally, Glycogen Synthase Kinase-3 inhibitors have been reported to enhance the adult hippocampal neurogenesis in vivo as well as in vitro. Keeping the chemotype of the reported Glycogen Synthase Kinase-3 inhibitors in consideration, they may be grouped into natural inhibitors, inorganic metal ions, organo-synthetic, and peptide like inhibitors. On the basis of their mode of binding to the constituent enzyme, they may also be grouped as ATP, nonATP, and allosteric binding sites competitive inhibitors. ATP competitive inhibitors were known earlier inhibitors but they lack efficient selectivity. This led to find the new ways for the enzyme inhibition.

The genetics of early-onset bipolar disorder: A systematic review

BACKGROUND

Early-onset bipolar disorder has been associated with a significantly worse prognosis than late-onset BD and has been hypothesized to be a genetically homogenous subset of BD. A sizeable number of studies have investigated early-onset BD through linkage-analyses, candidate-gene association studies, genome-wide association studies (GWAS), and analyses of copy number variants (CNVs), but this literature has not yet been reviewed.

METHODS

A systematic review was conducted using the PubMed database on articles published online before January 15, 2015 and after 1990. Separate searches were made for linkage studies, candidate gene-association studies, GWAS, and studies on CNVs.

RESULTS

Seventy-three studies were included in our review. There is a lack of robust positive findings on the genetics of early-onset BD in any major molecular genetics method.

LIMITATIONS

Early-onset populations were quite small in some studies. Variance in study methods hindered efforts to interpret results or conduct meta-analysis.

CONCLUSIONS

The field is still at an early phase for research on early-onset BD. The largely null findings mirror the results of most genetics research on BD. Although most studies were underpowered, the null findings could mean that early-onset BD may not be as genetically homogenous as has been hypothesized or even that early-onset BD does not differ genetically from adult-onset BD. Nevertheless, clinically the probabilistic developmental risk trajectories associated with early-onset that may not be primarily genetically determined continued to warrant scrutiny. Future research should dramatically expand sample sizes, use atheoretical research methods like GWAS, and standardize methods.

Chronobiology of bipolar disorder: therapeutic implication

Multiple lines of evidence suggest that psychopathological symptoms of bipolar disorder arise in part from a malfunction of the circadian system, linking the disease with an abnormal internal timing. Alterations in circadian rhythms and sleep are core elements in the disorders, characterizing both mania and depression and having recently been shown during euthymia. Several human genetic studies have implicated specific genes that make up the genesis of circadian rhythms in the manifestation of mood disorders with polymorphisms in molecular clock genes not only showing an association with the disorder but having also been linked to its phenotypic particularities. Many medications used to treat the disorder, such as antidepressant and mood stabilizers, affect the circadian clock. Finally, circadian rhythms and sleep researches have been the starting point of the developing of chronobiological therapies. These interventions are safe, rapid and effective and they should be considered first-line strategies for bipolar depression.

Subtle Impact of Akt1 and Akt3 on Exploratory Behavior in Gene Targeted Mice

Abstract. The present study explored the impact of Akt1 and Akt3 on behavior. Akt1 (akt1-/-) and Akt3 (akt3-/-) knockout mice were compared to wild type (wt) mice. The akt1-/- mice, akt3-/- mice, and wt mice were similar in most parameters of the open-field test. However, the distance traveled in the center area was slightly but significantly less in akt3-/- mice than in wt mice. In the light/dark transition test akt1-/- mice had significantly lower values than wt mice and akt3-/- mice for distance traveled, number of rearings, rearing time in the light area, as well as time spent and distance traveled in the entrance area. They were significantly different from akt3-/- mice in the distance traveled, visits, number of rearings, rearing time in the light area, as well as time spent, distance traveled, number of rearings, and rearing time in the entrance area. In the O-maze the time spent, and the visits to open arms, as well as the number of protected and unprotected headdips were significantly less in akt1-/- mice than in wt mice, whereas the time spent in closed arms was significantly more in akt1-/- mice than in wt mice. Protected and unprotected headdips were significantly less in akt3-/- mice than in wt mice. In closed area, akt3-/- mice traveled a significantly larger distance at larger average speed than akt1-/- mice. No differences were observed between akt1-/- mice, akt3-/- mice and wt-type mice in the time of floating during the forced swimming test. In conclusion, akt1-/- mice and less so akt3-/ mice display subtle changes in behavior.

Phosphoinositide-Dependent Protein Kinase 1 (PDK1)

Abstract. Phosphatidylinositol-3-kinase (PI3K) signaling influences susceptibility to virus infections, anoxia, obstetric complications, and cancer; which are changed in patients with schizophrenia and their first degree relatives. Therefore PI3K signaling might have impact on the pathophysiology of schizophrenia. PI3K signaling crucially involves phosphoinositide-dependent protein kinase (PDK1). Increased anxiety behavior is observed in PDK1 hypomorphic mice. Here we show enhanced prevalence of schizophrenia in carriers of the PDK1 CC genotype in human beings. Moreover, decreased parietal P300 amplitude, which is a well-studied schizophrenic endophenotype, was observed in PDK1 CC carriers. Glutamate and glutamine concentrations are increased in the frontal lobe of PDK1 dysmorphic mice and human CC individuals. Our results demonstrate that the PDK1 CC genotype is associated with increased risk to develop schizophrenia, a typical endophenotype profile observed in the disease and modified neurotransmitter concentrations in brain regions associated with the disease.

Learning from the past and looking to the future: Emerging perspectives for improving the treatment of psychiatric disorders

Modern neuropsychopharmacology commenced in the 1950s with the serendipitous discovery of first-generation antipsychotics and antidepressants which were therapeutically effective yet had marked adverse effects. Today, a broader palette of safer and better-tolerated agents is available for helping people that suffer from schizophrenia, depression and other psychiatric disorders, while complementary approaches like psychotherapy also have important roles to play in their treatment, both alone and in association with medication. Nonetheless, despite considerable efforts, current management is still only partially effective, and highly-prevalent psychiatric disorders of the brain continue to represent a huge personal and socio-economic burden. The lack of success in discovering more effective pharmacotherapy has contributed, together with many other factors, to a relative disengagement by pharmaceutical firms from neuropsychiatry. Nonetheless, interest remains high, and partnerships are proliferating with academic centres which are increasingly integrating drug discovery and translational research into their traditional activities. This is, then, a time of transition and an opportune moment to thoroughly survey the field. Accordingly, the present paper, first, chronicles the discovery and development of psychotropic agents, focusing in particular on their mechanisms of action and therapeutic utility, and how problems faced were eventually overcome. Second, it discusses the lessons learned from past successes and failures, and how they are being applied to promote future progress. Third, it comprehensively surveys emerging strategies that are (1), improving our understanding of the diagnosis and classification of psychiatric disorders; (2), deepening knowledge of their underlying risk factors and pathophysiological substrates; (3), refining cellular and animal models for discovery and validation of novel therapeutic agents; (4), improving the design and outcome of clinical trials; (5), moving towards reliable biomarkers of patient subpopulations and medication efficacy and (6), promoting collaborative approaches to innovation by uniting key partners from the regulators, industry and academia to patients. Notwithstanding the challenges ahead, the many changes and ideas articulated herein provide new hope and something of a framework for progress towards the improved prevention and relief of psychiatric and other CNS disorders, an urgent mission for our Century.

Lithium and GSK-3β promoter gene variants influence cortical gray matter volumes in bipolar disorder

RATIONALE

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase-3β (GSK-3β). The less active GSK-3β promoter gene variants have been associated with less detrimental clinical features of BD. GSK-3β gene variants and lithium can influence brain gray and white matter structure in psychiatric conditions, so we studied their combined effect in BD.

OBJECTIVES

The aim of this study is to investigate the effects of ongoing long-term lithium treatment and GSK-3β promoter rs334558 polymorphism on regional gray matter (GM) volumes of patients with BD.

MATERIALS AND METHODS

GM volumes were estimated with 3.0 Tesla MRI in 150 patients affected by a major depressive episode in course of BD. Duration of lifetime lithium treatment was retrospectively assessed. Analyses were performed by searching for significant effects of lithium and rs334558 in the whole brain.

RESULTS

The less active GSK-3β rs334558*G gene promoter variant and the long-term administration of lithium were synergistically associated with increased GM volumes in the right frontal lobe, in a large cluster encompassing the boundaries of subgenual and orbitofrontal cortex (including Brodmann areas 25, 11, and 47). Effects of lithium on GM revealed in rs334558*G carriers only, consistent with previously reported clinical effects in these genotype groups, and were proportional to the duration of treatment.

CONCLUSIONS

Lithium and rs334558 influenced GM volumes in areas critical for the generation and control of affect, which have been widely implicated in the process of BD pathophysiology. In the light of the protective effects of lithium on white matter integrity, our results suggest that the clinical effects of lithium associate with a neurotrophic effect on the whole brain, probably mediated by GSK-3β inhibition.

The elements of life and medicines

Which elements are essential for human life? Here we make an element-by-element journey through the periodic table and attempt to assess whether elements are essential or not, and if they are, whether there is a relevant code for them in the human genome. There are many difficulties such as the human biochemistry of several so-called essential elements is not well understood, and it is not clear how we should classify elements that are involved in the destruction of invading microorganisms, or elements which are essential for microorganisms with which we live in symbiosis. In general, genes do not code for the elements themselves, but for specific chemical species, i.e. for the element, its oxidation state, type and number of coordinated ligands, and the coordination geometry. Today, the biological periodic table is in a position somewhat similar to Mendeleev's chemical periodic table of 1869: there are gaps and we need to do more research to fill them. The periodic table also offers potential for novel therapeutic and diagnostic agents, based on not only essential elements, but also non-essential elements, and on radionuclides. Although the potential for inorganic chemistry in medicine was realized more than 2000 years ago, this area of research is still in its infancy. Future advances in the design of inorganic drugs require more knowledge of their mechanism of action, including target sites and metabolism. Temporal speciation of elements in their biological environments at the atomic level is a major challenge, for which new methods are urgently needed.

Zinc: indications in brain disorders

Zinc is the authoritative metal which is present in our body, and reactive zinc metal is crucial for neuronal signaling and is largely distributed within presynaptic vesicles. Zinc also plays an important role in synaptic function. At cellular level, zinc is a modulator of synaptic activity and neuronal plasticity in both development and adulthood. Different importers and transporters are involved in zinc homeostasis. ZnT-3 is a main transporter involved in zinc homeostasis in the brain. It has been found that alterations in brain zinc status have been implicated in a wide range of neurological disorders including impaired brain development and many neurodegenerative disorders such as Alzheimer's disease, and mood disorders including depression, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and prion disease. Furthermore, zinc has also been implicated in neuronal damage associated with traumatic brain injury, stroke, and seizure. Understanding the mechanisms that control brain zinc homeostasis is thus critical to the development of preventive and treatment strategies for these and other neurological disorders.

N-butylidenephthalide attenuates Alzheimer's disease-like cytopathy in Down syndrome induced pluripotent stem cell-derived neurons

Down syndrome (DS) patients with early-onset dementia share similar neurodegenerative features with Alzheimer's disease (AD). To recapitulate the AD cell model, DS induced pluripotent stem cells (DS-iPSCs), reprogrammed from mesenchymal stem cells in amniotic fluid, were directed toward a neuronal lineage. Neuroepithelial precursor cells with high purity and forebrain characteristics were robustly generated on day 10 (D10) of differentiation. Accumulated amyloid deposits, Tau protein hyperphosphorylation and Tau intracellular redistribution emerged rapidly in DS neurons within 45 days but not in normal embryonic stem cell-derived neurons. N-butylidenephthalide (Bdph), a major phthalide ingredient of Angelica sinensis, was emulsified by pluronic F127 to reduce its cellular toxicity and promote canonical Wnt signaling. Interestingly, we found that F127-Bdph showed significant therapeutic effects in reducing secreted Aβ40 deposits, the total Tau level and the hyperphosphorylated status of Tau in DS neurons. Taken together, DS-iPSC derived neural cells can serve as an ideal cellular model of DS and AD and have potential for high-throughput screening of candidate drugs. We also suggest that Bdph may benefit DS or AD treatment by scavenging Aβ aggregates and neurofibrillary tangles.

Haplotype analysis of GSK-3β gene polymorphisms in bipolar disorder lithium responders and nonresponders

The GSK-3β gene, GSK3B, codes for an enzyme that is a target for the action of mood stabilizers, lithium and possibly valproic acid.

In this study, the relationship between haplotypes consisting of single nucleotide polymorphisms (SNPs) of GSK3B −50T/C and −1727A/T and the effect of lithium was studied among Japanese bipolar disorder lithium nonresponders and responders.

The distributions of the GSK3B haplotypes (−50T/C and −1727A/T) showed a trend for significant difference between the lithium nonresponders and responders (global P=0.07074). Haplotype 1 (T-A) was associated with a higher lithium response (haplotype-specific P=0.03477), whereas haplotype 2 (C-A) was associated with a lower lithium response (haplotype-specific P=0.03443).

The pairwise D′ and r² values between the 2 SNPs in this study were 1.0 and 0.097, respectively. The 2 SNPs showed weak linkage disequilibrium with each other.

The promise of ketamine for treatment-resistant depression: current evidence and future directions

Major depressive disorder (MDD) is one of the most disabling diseases worldwide and is becoming a significant public health threat. Current treatments for MDD primarily consist of monoamine-targeting agents and have limited efficacy. However, the glutamate neurotransmitter system has recently come into focus as a promising alternative for novel antidepressant treatments. We review the current data on the glutamate NMDA receptor antagonist ketamine, which has been shown in clinical trials to act as a rapid antidepressant in MDD. We also examine ketamine efficacy on dimensions of psychopathology, including anhedonia, cognition, and suicidality, consistent with the NIMH Research Domain Criteria initiative. Other aspects of ketamine reviewed in this paper include safety and efficacy, different administration methods, and the risks of misuse of ketamine outside of medical settings. Finally, we conclude with a discussion of glutamatergic agents other than ketamine currently being tested as novel antidepressants.

Aripiprazole: from pharmacological profile to clinical use

Clinical experience with aripiprazole has confirmed the effectiveness and the safety of this novel antipsychotic drug in patients with schizophrenia as well as for the treatment of mania in type I bipolar disorder. However the generalization of the results from clinical trials requires further effort in order to address some issues and to overcome incorrect and partial interpretation of the clinical evidence. This article provides some straightforward guidance that may help clinical psychiatrists to translate the mechanism of action of aripiprazole into clinical setting, thus improving the appropriate use of the drug through rational application of its pharmacological profile. Examples of paradigmatic clinical situations are presented and discussed, suggesting possible intervention strategies, which may contribute to achieving the most appropriate use of the pharmacological properties of aripiprazole in real life settings.

Sustained behavioral effects of lithium exposure during early development in zebrafish: involvement of the Wnt-β-catenin signaling pathway

Lithium has been the paradigmatic treatment for bipolar disorder since 1950s, offering prophylactic and acute efficacy against maniac and depressive episodes. Its use during early pregnancy and the perinatal period remains controversial due to reports of negative consequences on the newborn including teratogenic and neurobehavioral effects generally referred as Floppy baby syndrome. The mechanisms underlying lithium therapeutic action are still elusive but exacerbation of Wnt signaling pathway due to GSK-3 inhibition is believed to represent its main effect. In this study we evaluated the impact of lithium exposure during zebrafish embryonic and early development including behavioral and molecular characterization of Wnt-β-catenin pathway components. Wild-type zebrafish embryos were individually treated for 72 hpf with LiCl at 0.05, 0.5 and 5mM. No significant teratogenic and embryotoxic effects were observed. At the end of treatment period western blot analysis of selected Wnt-β-catenin system components showed increased β-catenin and decreased N-cadherin protein levels, without significant changes in Wnt3a, supporting GSK-3 inhibition as lithium's main target. At 10 dpf 0.5 and 5mM lithium-treated larvae showed a dose-dependent decrease in locomotion among other exploratory parameters, resembling lithium-induced Floppy baby syndrome neurobehavioral symptoms in humans. At this later period previously altered proteins returned to control levels in treated groups, suggesting that the neurobehavioral effects are a lasting consequence of lithium exposure during early development. RT-qPCR analysis of β-catenin and N-cadherin gene expression showed no effects of lithium at 3 or 10 dpf, suggesting that protein fluctuations were likely due to post-transcriptional events. Other Wnt target genes were evaluated and only discrete alterations were observed. These results suggest that zebrafish may be a valuable model for investigation of early effects of lithium that may be mediated by effects on the Wnt signaling pathway.

The activation of the Akt/PKB signalling pathway in the brains of clozapine-exposed rats is linked to hyperinsulinemia and not a direct drug effect

The second generation antipsychotic drug clozapine is a much more effective therapy for schizophrenia than first generation compounds, but the reasons for this are poorly understood. We have previously shown that one distinguishing feature of clozapine is its ability to raise glucagon levels in animal models and thus causes prolonged hyperinsulinemia without inducing hypoglycaemia. Previous studies have provided evidence that defects in Akt/PKB and GSK3 signalling can contribute to development of psychiatric diseases. Clozapine is known to activate Akt/PKB in the brain, and some studies have indicated that this is due to a direct effect of the drug on the neurons. However, we provide strong evidence that elevated insulin levels induced by clozapine are in fact the real cause of the drug's effects on Akt/PKB and GSK3 in the brain. This suggests that the elevated levels of insulin induced by clozapine may contribute to this drug's therapeutic efficacy.

A combined study of GSK3β polymorphisms and brain network topological metrics in major depressive disorder

GSK3β genotypes may interact with major depressive disorder (MDD) and may have a role in determining regional gray matter volume differences from healthy comparison subjects. However, any associations of GSK3β genotypes with MDD related to abnormal functional brain activity have yet to be elucidated. In the present study, resting state functional brain networks were constructed by thresholding partial correlation matrices of 90 regions. Differences in the network features of GSK3β-rs6438552 genotypes were tested, and a 2×2 analysis of variance was performed to identify the main effects of genotypes, disease status, and their interactions in MDD. Compared with CC carriers, T+ carriers with MDD showed increased nodal centralities in many brain regions-mainly the limbic system, thalamus and parts of the parietal, temporal, occipital, and frontal regions. Decreased nodal centralities predominantly occurred in the sensorimotor area and parts of the frontal, occipital, and temporal lobes. Significant interactions between genotypes and disease status were found in the left thalamus, left superior occipital gyrus, and left inferior parietal lobe. Only altered nodal centrality in the left angular gyrus was negatively correlated with scores on the Hamilton Depression Rating Scale. Our results suggest the GSK3β genotypic effect of rs6438552 and its interaction with disease status may contribute to the altered topological organization of resting state functional brain networks in MDD patients.

Standard and trace-dose lithium: a systematic review of dementia prevention and other behavioral benefits

OBJECTIVE

Dementia is a major public health issue, with notably high rates in persons with mood illnesses. Lithium has been shown to have considerable neuroprotective effects, even in trace or low doses. The aim of this review is to summarize the current understanding of lithium benefits in trace or low doses in dementia prevention and for other behavioral or medical benefits.

METHODS

A systematic review identified 24 clinical, epidemiological, and biological reports that met inclusion criteria of assessing lithium in standard or low doses for dementia or other behavioral or medical benefits.

RESULTS

Five out of seven epidemiological studies found an association between standard-dose lithium and low dementia rates. Nine out of 11 epidemiological studies, usually of drinking water sources, found an association between trace-dose lithium and low suicide/homicide/mortality and crime rates. All four small randomized clinical trials of lithium for Alzheimer's dementia have found at least some clinical or biological benefits versus placebo. Only one small randomized clinical trial (RCT) of trace lithium has been conducted, assessing mood symptoms in former substance abusers, and found benefit with lithium versus placebo.

CONCLUSIONS

Lithium, in both standard and trace doses, appears to have biological benefits for dementia, suicide, and other behavioral outcomes. Further RCT research of trace lithium in dementia is warranted.

Reduced striatal dopamine DA D2 receptor function in dominant-negative GSK-3 transgenic mice

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase with constitutive activity involved in cellular architecture, gene expression, cell proliferation, fate decision and apoptosis, among others. GSK-3 expression is particularly high in brain where it may be involved in neurological and psychiatric disorders such as Alzheimer׳s disease, bipolar disorder and major depression. A link with schizophrenia is suggested by the antipsychotic drug-induced GSK-3 regulation and by the involvement of the Akt/GSK-3 pathway in dopaminergic neurotransmission. Taking advantage of the previous development of dominant negative GSK-3 transgenic mice (Tg) showing a selective reduction of GSK-3 activity in forebrain neurons but not in dopaminergic neurons, we explored the relationship between GSK-3 and dopaminergic neurotransmission in vivo. In microdialysis experiments, local quinpirole (DA D2-R agonist) in dorsal striatum reduced dopamine (DA) release significantly less in Tg mice than in wild-type (WT) mice. However, local SKF-81297 (selective DA D1-R agonist) in dorsal striatum reduced DA release equally in both control and Tg mice indicating a comparable function of DA D1-R in the direct striato-nigral pathway. Likewise, systemic quinpirole administration - acting preferentially on presynaptic DA D2- autoreceptors to modulate DA release-reduced striatal DA release similarly in both control and Tg mice. Quinpirole reduced locomotor activity and induced c-fos expression in globus pallidus (both striatal DA D2-R-mediated effects) significantly more in WT than in Tg mice. Taking together, the present results show that dominant negative GSK-3 transgenic mice show reduced DA D2-R-mediated function in striatum and further support a link between dopaminergic neurotransmission and GSK-3 activity.

The relationships between clinical characteristics, alcohol and psychotropic exposure, and circadian gene expression in human postmortem samples of affective disorder and control subjects

Circadian abnormalities may be related to mood disorders. Circadian gene expression was measured in postmortem brain tissue from individuals with affective disorders and controls. Relationships between circadian gene expression, clinical characteristics, and alcohol and psychotropic medication use were noted. Further study is warranted to characterize these relationships.

Response to lithium in bipolar disorder: clinical and genetic findings

The use of lithium is a cornerstone for preventing recurrences in bipolar disorder (BD). The response of patients with bipolar disorder to lithium has different levels of magnitude. About one-third of lithium-treated patients are excellent lithium responders (ELR), showing total prevention of the episodes. A number of clinical characteristics were delineated in patients with favorable response to lithium as regards to clinical course, family history of mood disorders, and psychiatric comorbidity. We have also demonstrated that temperamental features of hypomania (a hyperthymic temperament) and a lack of cognitive disorganization predict the best results of lithium prophylaxis. A degree of prevention against manic and depressive episodes has been regarded as an endophenotype for pharmacogenetic studies. The majority of data have been gathered from so-called "candidate" gene studies. The candidates were selected on the basis of neurobiology of bipolar disorder and mechanisms of lithium action including, among others, neurotransmission, intracellular signaling, neuroprotection or circadian rhythms. We demonstrated that response to lithium has been connected with the genotype of BDNF gene and serum BDNF levels and have shown that ELR have normal cognitive functions and serum BDNF levels, even after long-term duration of the illness. A number of genome-wide association studies (GWAS) of BD have been also performed in recent years, some of which also focused on lithium response. The Consortium on Lithium Genetics (ConLiGen) has established the large sample for performing the genome-wide association study (GWAS) of lithium response in BD, and the first results have already been published.

Pharmacological and toxicological effects of lithium in zebrafish

Lithium is the paradigmatic treatment for bipolar disorder and has been widely used as a mood stabilizer due to its ability to reduce manic and depressive episodes, efficiency in long-term mood stabilization, and effectiveness in reducing suicide risks. Despite many decades of clinical use, the molecular targets of lithium are not completely understood. However, they are credited at least partially to glycogen synthase kinase 3 (GSK3) inhibition, mimicking and exacerbating Wnt signaling pathway activation. There has been a great effort to characterize lithium cellular and system actions, aiming to improve treatment effectiveness and reduce side effects. There is also a growing concern about lithium's impact as an environmental contaminant and its effects on development. In this scenario, zebrafish is a helpful model organism to gather more information on lithium's effects in different systems and developmental stages. The rapid external development, initial transparency, capacity to easily absorb substances, and little space required for maintenance and experimentation, among other advantages, make zebrafish a suitable model. In addition, zebrafish has been established as an effective model organism in behavioral and neuropharmacological studies, reacting to a wide range of psychoactive drugs, including lithium. So far only a limited number of studies evaluated the toxicological impact of lithium on zebrafish development and demonstrated morphological, physiological, and behavioral effects that may be informative regarding human findings. Further studies dedicated to characterize and evaluate the underlying mechanisms of the toxic effects and the potential impact of exposure on developing and adult individuals are necessary to establish safe clinical management guidelines for women with bipolar disorder of childbearing age and safety disposal guidelines for pharmaceutical neuroactive compounds.

The emerging role of dopamine-glutamate interaction and of the postsynaptic density in bipolar disorder pathophysiology: Implications for treatment

Aberrant synaptic plasticity, originating from abnormalities in dopamine and/or glutamate transduction pathways, may contribute to the complex clinical manifestations of bipolar disorder (BD). Dopamine and glutamate systems cross-talk at multiple levels, such as at the postsynaptic density (PSD). The PSD is a structural and functional protein mesh implicated in dopamine and glutamate-mediated synaptic plasticity. Proteins at PSD have been demonstrated to be involved in mood disorders pathophysiology and to be modulated by antipsychotics and mood stabilizers. On the other side, post-receptor effectors such as protein kinase B (Akt), glycogen synthase kinase-3 (GSK-3) and the extracellular signal-regulated kinase (Erk), which are implicated in both molecular abnormalities and treatment of BD, may interact with PSD proteins, and participate in the interplay of the dopamine-glutamate signalling pathway. In this review, we describe emerging evidence on the molecular cross-talk between dopamine and glutamate signalling in BD pathophysiology and pharmacological treatment, mainly focusing on dysfunctions in PSD molecules. We also aim to discuss future therapeutic strategies that could selectively target the PSD-mediated signalling cascade at the crossroads of dopamine-glutamate neurotransmission.

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.

The relationship between affective state and the rhythmicity of activity in bipolar disorder

OBJECTIVE

The aim of this study was to test the relationships between mood state and rhythm disturbances as measured via actigraphy in bipolar disorder by assessing the correlations between manic and depressive symptoms as measured via Young Mania Rating Scale (YMRS) and 30-item Inventory for Depressive Symptomatology, Clinician-Rated (IDS-C-30) scores and the actigraphic measurements of rhythm, the 24-hour autocorrelation coefficient and circadian quotient.

METHOD

The research was conducted at the University of Texas Southwestern Medical Center at Dallas from February 2, 2009, to March 30, 2010. 42 patients with a DSM-IV-TR diagnosis of bipolar I disorder were included in the study. YMRS and the IDS-C-30 were used to determine symptom severity. Subjects wore the actigraph continuously for 7 days. The 24-hour autocorrelation coefficient was used as an indicator of overall rhythmicity. The circadian quotient was used to characterize the strength of a circadian rhythm.

RESULTS

A greater severity of manic symptoms correlated with a lower degree of rhythmicity and less robust rhythms of locomotor activity as indicated by lower 24-hour autocorrelation (r = -0.3406, P = .03) and circadian quotient (r = -0.5485, P = .0002) variables, respectively. No relationship was noted between the degree of depression and 24-hour autocorrelation scores (r = -0.1190, P = .45) or circadian quotient (r = 0.0083, P = .96). Correlation was noted between the 24-hour autocorrelation and circadian quotient scores (r = 0.6347, P < .0001).

CONCLUSIONS

These results support the notion that circadian rhythm disturbances are associated with bipolar disorder and that these disturbances may be associated with clinical signatures of the disorder. Further assessment of rhythm disturbances in bipolar disorder is warranted.

Molecular actions and clinical pharmacogenetics of lithium therapy

Mood disorders, including bipolar disorder and depression, are relatively common human diseases for which pharmacological treatment options are often not optimal. Among existing pharmacological agents and mood stabilizers used for the treatment of mood disorders, lithium has a unique clinical profile. Lithium has efficacy in the treatment of bipolar disorder generally, and in particular mania, while also being useful in the adjunct treatment of refractory depression. In addition to antimanic and adjunct antidepressant efficacy, lithium is also proven effective in the reduction of suicide and suicidal behaviors. However, only a subset of patients manifests beneficial responses to lithium therapy and the underlying genetic factors of response are not exactly known. Here we discuss preclinical research suggesting mechanisms likely to underlie lithium's therapeutic actions including direct targets inositol monophosphatase and glycogen synthase kinase-3 (GSK-3) among others, as well as indirect actions including modulation of neurotrophic and neurotransmitter systems and circadian function. We follow with a discussion of current knowledge related to the pharmacogenetic underpinnings of effective lithium therapy in patients within this context. Progress in elucidation of genetic factors that may be involved in human response to lithium pharmacology has been slow, and there is still limited conclusive evidence for the role of a particular genetic factor. However, the development of new approaches such as genome-wide association studies (GWAS), and increased use of genetic testing and improved identification of mood disorder patients sub-groups will lead to improved elucidation of relevant genetic factors in the future.

Plasma and Brain Pharmacokinetics of Previously Unexplored Lithium Salts

Despite its narrow therapeutic window, lithium is still regarded as the gold standard comparator and benchmark treatment for mania. Recent attempts to find new drugs with similar therapeutic activities have yielded new chemical entities. However, these potential new drugs have yet to match the many bioactivities attributable to lithium's efficacy for the treatment of neuropsychiatric diseases. Consequently, an intense effort for re-engineering lithium therapeutics using crystal engineering is currently underway. We sought to improve the likelihood of success of these endeavors by evaluating the pharmacokinetics of previously unexplored lithium salts with organic anions (lithium salicylate and lithium lactate). We report that these lithium salts exhibit profoundly different pharmacokinetics compared to the more common FDA approved salt, lithium carbonate, in rats. Remarkably, lithium salicylate produced elevated plasma and brain levels of lithium beyond 48 hours post-dose without the sharp peak that contributes to the toxicity problems of current lithium therapeutics. These findings could be important for the development of the next generation of lithium therapeutics.