A role for Akt and glycogen synthase kinase-3 as integrators of dopamine and serotonin neurotransmission in mental health

The use of optical coherence tomography in the evaluation of patients with bipolar disorder

Bipolar disorder (BD) is a mental disorder characterised by episodes of extremal mood changes. In recent years, some researchers found neurodegeneration in patients with BD using Magnetic Resonance Imaging. Evaluation of the optic nerve and the retinal layers using optical coherence tomography (OCT) has proved to be a useful, non-invasive tool for diagnosis and monitoring of neurodegenerative diseases. Accordingly, a decrease in the retinal nerve fibre layer and the ganglion cell complex measured by OCT was found in patients with BD in different studies, suggesting that BD is a neurodegenerative process in addition to a psychiatric disorder. Therefore, the neuro-ophthalmological evaluation of these patients could be used as a marker for diagnosis of this disease. This work analyses literature on retinal degeneration in bipolar disorder patients, and evaluates the ability of OCT devices in the detection of neuronal degeneration affecting the different retinal layers in these patients, and its possible role in the diagnosis and monitoring of the disease.

Amino acids profiles of children who stutter compared to their fluent sibling

Purpose: This study scrutinises the abundances of 9 neurological-related amino acids of the scalp hair of 35 (5 females, 30 males) children who stutter and 30 normally fluent children (age and sex matched).Methods: Samples of hair from children who stutter aged (5-9 years) were collected from Speech Clinic at King Abdullah Hospital. The control subjects were selected from the same families of children who stutter to exclude the effect of nutritional, environmental, and biological factors. Amino Acid Analyser was used to measure the concentrations of amino acids in acid hydrolysed hair samples.Results: results indicated that the concentrations of threonine, tyrosine, and isoleucine (p = 0.001, 0.001, 0.02 respectively) are lower in hair samples of people who stutter compared with samples of normal fluent speakers.Conclusion: The findings of this study could introduce a new treatment protocol including the supplementation of reduced nutritional elements.KEY POINTSConcentrations of amino acids (threonine, isoleucine, and tyrosine) in the hair samples of people who stutter were significantly lower than the concentrations in the hair samples of control group.Concentrations of amino acids (histidine and glutamate) in hair samples of people who stutter were lower than control group with low significant values.The concentrations of amino acids (phenylalanine, serine, glycine, aspartate, glutamate) were not significantly different between hair samples of stuttering group and control group.The findings of the current study will be helpful in designing a new treatment method based on the supplementation of deficient amino acids.

NRG1, PIP4K2A, and HTR2C as Potential Candidate Biomarker Genes for Several Clinical Subphenotypes of Depression and Bipolar Disorder

GSK3B, BDNF, NGF, NRG1, HTR2C, and PIP4K2A play important roles in molecular mechanisms of psychiatric disorders. GSK3B occupies a central position in these molecular mechanisms and is also modulated by psychotropic drugs. BDNF regulates a number of key aspects in neurodevelopment and synaptic plasticity. NGF exerts a trophic action and is implicated in cerebral alterations associated with psychiatric disorders. NRG1 is active in neural development, synaptic plasticity, and neurotransmission. HTR2C is another important psychopharmacological target. PIP4K2A catalyzes the phosphorylation of PI5P to form PIP2, the latter being implicated in various aspects of neuronal signal transduction. In the present study, the six genes were sequenced in a cohort of 19 patients with bipolar affective disorder, 41 patients with recurrent depressive disorder, and 55 patients with depressive episode. The study revealed a number of genetic variants associated with antidepressant treatment response, time to recurrence of episodes, and depression severity. Namely, alleles of rs35641374 and rs10508649 (NRG1 and PIP4K2A) may be prognostic biomarkers of time to recurrence of depressive and manic/mixed episodes among patients with bipolar affective disorder. Alleles of NC_000008.11:g.32614509_32614510del, rs61731109, and rs10508649 (also NRG1 and PIP4K2A) seem to be predictive biomarkers of response to pharmacological antidepressant treatment on the 28th day assessed by the HDRS-17 or CGI-I scale. In particular, the allele G of rs10508649 (PIP4K2A) may increase resistance to antidepressant treatment and be at the same time protective against recurrent manic/mixed episodes. These results support previous data indicating a biological link between resistance to antidepressant treatment and mania. Bioinformatic functional annotation of associated variants revealed possible impact for transcriptional regulation of PIP4K2A. In addition, the allele A of rs2248440 (HTR2C) may be a prognostic biomarker of depression severity. This allele decreases expression of the neighboring immune system gene IL13RA2 in the putamen according to the GTEx portal. The variant rs2248440 is near rs6318 (previously associated with depression and effects of psychotropic drugs) that is an eQTL for the same gene and tissue. Finally, the study points to several protein interactions relevant in the pathogenesis of mood disorders. Functional studies using cellular or animal models are warranted to support these results.

The increased density of the habenular neurons, high impulsivity, aggression and resistant fear memory in Disc1-Q31L genetic mouse model of depression

Mood disorders affect nearly 300 million humans worldwide, and it is a leading cause of death from suicide. In the last decade, the habenula has gained increased attention due to its major role to modulate emotional behavior and related psychopathologies, including depression and bipolar disorder, through the modulation of monoamines' neurotransmission. However, it is still unclear which genetic factors may directly affect the function of the habenula and hence, could contribute to the psychopathological mechanisms of mood disorders. Disrupted-In-Schizophrenia-1 (DISC1) gene is among robust gene-candidates predisposing to major depression, bipolar disorder and schizophrenia in humans. DISC1-Q31L, a well-established genetic mouse model of depression, offers a unique opportunity for translational studies. The current study aimed to probe morphological features of the habenula in the DISC1-Q31L mouse line and detect novel behavioral endophenotypes, including the increased emotionality in mutant females, high aggression in mutant males and deficient extinction of fear memory in DISC1 mutant mice of both sexes. The histological analysis found the increased neural density in the lateral and medial habenula in DISC1-Q31L mice regardless of sex, hence, excluding direct association between the habenular neurons and emotionality in mutant females. Altogether, our findings demonstrated, for the first time, the direct impact of the DISC1 gene on the habenular neurons and affective behavior in the DISC1-Q31L genetic mouse line. These new findings suggest that the combination of the DISC1 genetic analysis together with habenular neuroimaging may improve diagnostics of mood disorder in clinical studies.

Antagonists of the serotonin receptor 5A target human breast tumor initiating cells

Background

Breast tumor initiating cells (BTIC) are stem-like cells that initiate and sustain tumor growth, and drive disease recurrence. Identifying therapies targeting BTIC has been hindered due primarily to their scarcity in tumors. We previously reported that BTIC frequency ranges between 15% and 50% in multiple mammary tumors of 3 different transgenic mouse models of breast cancer and that this frequency is maintained in tumor cell populations cultured in serum-free, chemically defined media as non-adherent tumorspheres. The latter enabled high-throughput screening of small molecules for their capacity to affect BTIC survival. Antagonists of several serotonin receptors (5-HTRs) were among the hit compounds. The most potent compound we identified, SB-699551, selectively binds to 5-HT5A, a Gα_i/o protein coupled receptor (GPCR).

Methods

We evaluated the activity of structurally unrelated selective 5-HT5A antagonists using multiple orthogonal assays of BTIC frequency. Thereafter we used a phosphoproteomic approach to uncover the mechanism of action of SB-699551. To validate the molecular target of the antagonists, we used the CRISPR-Cas9 gene editing technology to conditionally knockout HTR5A in a breast tumor cell line.

Results

We found that selective antagonists of 5-HT5A reduced the frequency of tumorsphere initiating cells residing in breast tumor cell lines and those of patient-derived xenografts (PDXs) that we established. The most potent compound among those tested, SB-699551, reduced the frequency of BTIC in ex vivo assays and acted in concert with chemotherapy to shrink human breast tumor xenografts in vivo. Our phosphoproteomic experiments established that exposure of breast tumor cells to SB-699551 elicited signaling changes in the canonical Gα_i/o-coupled pathway and the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) axis. Moreover, conditional mutation of the HTR5A gene resulted in the loss of tumorsphere initiating cells and BTIC thus mimicking the effect of SB-699551.

Conclusions

Our data provide genetic, pharmacological and phosphoproteomic evidence consistent with the on-target activity of SB-699551. The use of such agents in combination with cytotoxic chemotherapy provides a novel therapeutic approach to treat breast cancer.

Lowered levels of nicotinic acetylcholine receptors and elevated apoptosis in the hippocampus of brains from patients with type 2 diabetes mellitus and db/db mice

Cognitive impairment caused by diabetes has been gradually recognized. Generally, nicotinic acetylcholine receptors (nAChRs) play an important role in the pathogenesis in dementia disorders including Alzheimer's disease (AD). However, the expression of nAChRs in the brains of type 2 diabetes mellitus (T2DM) is unexplored. This study explored the alterations of nAChRs in the postmortem brains of patients with T2DM and brains of db/db mice. Morris water maze test was used to appraise the ability of spatial learning and memory; Western blotting and RT-qPCR were performed to determine the expressions of target protein and mRNA, respectively; TUNEL was used to detect the apoptosis of neurons. We found that the protein levels of nAChR α7 and α4 subunits were significantly decreased and the apoptosis rates in neurons elevated in the hippocampus of T2DM patients and db/db mice as comparison to controls. Furthermore, the db/db mice exhibited the impaired cognition, the elevated level of pro-apoptotic protein and the reduced level of anti-apoptotic and synaptic proteins. This study shows the lowered level of nAChR α7 and α4 subunits and the elevated apoptosis in the hippocampus of T2DM patients and db/db mice, which might help explain the impaired cognition in T2DM.

Orphan G Protein Coupled Receptors in Affective Disorders

G protein coupled receptors (GPCRs) are the main mediators of signal transduction in the central nervous system. Therefore, it is not surprising that many GPCRs have long been investigated for their role in the development of anxiety and mood disorders, as well as in the mechanism of action of antidepressant therapies. Importantly, the endogenous ligands for a large group of GPCRs have not yet been identified and are therefore known as orphan GPCRs (oGPCRs). Nonetheless, growing evidence from animal studies, together with genome wide association studies (GWAS) and post-mortem transcriptomic analysis in patients, pointed at many oGPCRs as potential pharmacological targets. Among these discoveries, we summarize in this review how emotional behaviors are modulated by the following oGPCRs: ADGRB2 (BAI2), ADGRG1 (GPR56), GPR3, GPR26, GPR37, GPR50, GPR52, GPR61, GPR62, GPR88, GPR135, GPR158, and GPRC5B.

The DISC1 R264Q variant increases affinity for the dopamine D2 receptor and increases GSK3 activity

The Disrupted in schizophrenia 1 (DISC1) gene encodes a scaffolding protein that is involved in many neural functions such as neurogenesis, neural differentiation, embryonic neuron migration and neurotransmitter signalling. DISC1 was originally implicated in schizophrenia in a single family with a drastic mutation, a chromosomal translocation severing the mid-point of the gene (aa 598). Some common DISC1 variants have also been associated with schizophrenia in the general population, but those located far from the chromosomal translocation breakpoint likely have a different functional impact. We previously reported that DISC1 forms a protein complex with dopamine D2 receptor (D2R), the main target for antipsychotic medications. The D2R-DISC1 complex is elevated in brain tissue from schizophrenia patients and facilitates glycogen synthase kinase (GSK)-3 signaling. The DISC1 R264Q variant is located within the region that binds the D2R, and we found that this polymorphism increases the affinity of DISC1 for the D2R and promotes GSK3 activity. Our results suggest a possible mechanism by which this common polymorphism could affect aspects of brain function that are relevant to psychosis and schizophrenia. This provides additional insight into molecular mechanisms underlying schizophrenia that could be exploited in the development of novel pharmacological treatments.

GPR56/ADGRG1 is associated with response to antidepressant treatment

It remains unclear why many patients with depression do not respond to antidepressant treatment. In three cohorts of individuals with depression and treated with serotonin-norepinephrine reuptake inhibitor (N = 424) we show that responders, but not non-responders, display an increase of GPR56 mRNA in the blood. In a small group of subjects we also show that GPR56 is downregulated in the PFC of individuals with depression that died by suicide. In mice, we show that chronic stress-induced Gpr56 downregulation in the blood and prefrontal cortex (PFC), which is accompanied by depression-like behavior, and can be reversed by antidepressant treatment. Gpr56 knockdown in mouse PFC is associated with depressive-like behaviors, executive dysfunction and poor response to antidepressant treatment. GPR56 peptide agonists have antidepressant-like effects and upregulated AKT/GSK3/EIF4 pathways. Our findings uncover a potential role of GPR56 in antidepressant response.

Lithium effects on serine-threonine kinases activity: High throughput kinomic profiling of lymphoblastoid cell lines from excellent-responders and non-responders bipolar patients

Objectives: Lithium is the leading mood stabiliser for maintenance treatment in bipolar disorder (BD). However, response to lithium is heterogeneous with more than 60% of patients experiencing partial or no response. In vitro and in vivo molecular studies have reported the implication of kinases in the pathophysiology of BD.Methods: Since kinases are putative targets for lithium therapeutic action, we conducted the first pilot study using kinase array technology to evaluate the global serine/threonine kinases (STK) profiles in cell lines from BD I subtype patients classified as lithium excellent-responders (ER) and non-responder (NR) to lithium treatment.Results: We found significant differences in the basal STK profiles between ER and NR to lithium. We also tested lithium influence on the global STK profile and found no significant difference between ER vs NR cell lines.Conclusions: The results obtained in this exploratory study suggest that multiplex kinase activity profiling could provide a complementary approach in the study of biomarkers of therapeutic response in BD.

Ribosomal Protein S6 Hypofunction in Postmortem Human Brain Links mTORC1-Dependent Signaling and Schizophrenia

The mechanistic target of rapamycin (also known as mammalian target of rapamycin) (mTOR)-dependent signaling pathway plays an important role in protein synthesis, cell growth, and proliferation, and has been linked to the development of the central nervous system. Recent studies suggest that mTOR signaling pathway dysfunction could be involved in the etiopathogenesis of schizophrenia. The main goal of this study was to evaluate the status of mTOR signaling pathway in postmortem prefrontal cortex (PFC) samples of subjects with schizophrenia. For this purpose, we quantified the protein expression and phosphorylation status of the mTOR downstream effector ribosomal protein S6 as well as other pathway interactors such as Akt and GSK3β. Furthermore, we quantified the status of these proteins in the brain cortex of rats chronically treated with the antipsychotics haloperidol, clozapine, or risperidone. We found a striking decrease in the expression of total S6 and in its active phosphorylated form phospho-S6 (Ser235/236) in the brain of subjects with schizophrenia compared to matched controls. The chronic treatment with the antipsychotics haloperidol and clozapine affected both the expression of GSK3β and the activation of Akt [phospho-Akt (Ser473)] in rat brain cortex, while no changes were observed in S6 and phospho-S6 (Ser235/236) protein expression with any antipsychotic treatment. These findings provide further evidence for the involvement of the mTOR-dependent signaling pathway in schizophrenia and suggest that a hypofunctional S6 may have a role in the etiopathogenesis of this disorder.

GSK3β: A Master Player in Depressive Disorder Pathogenesis and Treatment Responsiveness

Glycogen synthase kinase 3β (GSK3β), originally described as a negative regulator of glycogen synthesis, is a molecular hub linking numerous signaling pathways in a cell. Specific GSK3β inhibitors have anti-depressant effects and reduce depressive-like behavior in animal models of depression. Therefore, GSK3β is suggested to be engaged in the pathogenesis of major depressive disorder, and to be a target and/or modifier of anti-depressants’ action. In this review, we discuss abnormalities in the activity of GSK3β and its upstream regulators in different brain regions during depressive episodes. Additionally, putative role(s) of GSK3β in the pathogenesis of depression and the influence of anti-depressants on GSK3β activity are discussed.

Neurodevelopmental concepts of schizophrenia in the genome-wide association era: AKT/mTOR signaling as a pathological mediator of genetic and environmental programming during development

Normative brain development is contingent on the complex interplay between genes and environment. Schizophrenia (SCZ) is considered a highly polygenic, neurodevelopmental disorder associated with impaired neural circuit development, neurocognitive function and variations in neurotransmitter signaling systems, including dopamine. Significant evidence, accumulated over the last 30 years indicates a role for the in utero environment in SCZ pathophysiology. Emerging data suggests that changes in placental programming and function may mediate the link between genetic risk, early life complications (ELC) and adverse neurodevelopmental outcomes, with risk highlighted in key developmental drivers that converge on AKT/mTOR signaling. In this article we overview select risk genes identified through recent genome-wide association studies of SCZ including AKT3, miR-137, DRD2, and AKT1 itself. We propose that through convergence on AKT/mTOR signaling, these genes are critical factors directing both placentation and neurodevelopment, influencing risk for SCZ through dysregulation of placental function, metabolism and early brain development. We discuss association of risk genes in the context of their known roles in neurodevelopment, placental expression and their possible mechanistic links to SCZ in the broad context of the 'developmental origins of adult disease' construct. Understanding how common genetic variation impacts early fetal programming may advance our knowledge of disease etiology and identify early critical developmental windows for prevention and intervention.

Overlap in the neural circuitry and molecular mechanisms underlying ketamine abuse and its use as an antidepressant

Ketamine, a dissociative anesthetic and psychedelic compound, has revolutionized the field of psychopharmacology by showing robust, and rapid-acting antidepressant activity in patients suffering from major depressive disorder (MDD), suicidal tendencies, and treatment-resistant depression (TRD). Ketamine's efficacy, however, is transient, and patients must return to the clinic for repeated treatment as they experience relapse. This is cause for concern because ketamine is known for its abuse liability, and repeated exposure to drugs of abuse often leads to drug abuse/dependence. Though the mechanism(s) underlying its antidepressant activity is an area of current intense research, both clinical and preclinical evidence shows that ketamine's effects are mediated, at least in part, by molecular adaptations resulting in long-lasting synaptic changes in mesolimbic brain regions known to regulate natural and drug reward. This review outlines our limited knowledge of ketamine's neurobiological and biochemical underpinnings mediating its antidepressant effects and correlates them to its abuse potential. Depression and addiction share overlapping neural circuitry and molecular mechanisms, and though speculative, repeated use of ketamine for the treatment of depression could lead to the development of substance use disorder/addiction, and thus should be tempered with caution. There is much that remains to be known about the long-term effects of ketamine, and our lack of understanding of neurobiological mechanisms underlying its antidepressant effects is a clear limiting factor that needs to be addressed systematically before using repeated ketamine in the treatment of depressed patients.

Lithium and coronaviral infections. A scoping review

The current rapid spread of the novel coronavirus (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) calls for a rapid response from the research community. Lithium is widely used to treat bipolar disorder, but has been shown to exhibit antiviral activity. This brief review took a systematic approach to identify six in vitro studies reporting on the influence of lithium on coronaviral infections. We propose mechanistic investigation of the influence of lithium - alone and with chloroquine - on the SARS-CoV-2 infection.

Lithium and coronaviral infections. A scoping review

The current rapid spread of the novel coronavirus (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) calls for a rapid response from the research community. Lithium is widely used to treat bipolar disorder, but has been shown to exhibit antiviral activity. This brief review took a systematic approach to identify six in vitro studies reporting on the influence of lithium on coronaviral infections. We propose mechanistic investigation of the influence of lithium – alone and with chloroquine – on the SARS-CoV-2 infection.

AKT1 and genetic vulnerability to bipolar disorder

AKT1 encodes a serine/threonine kinase that has as one of its best-known substrates glycogen synthase kinase-3 (GSK3), a primary target for lithium. AKT1 has been previously been implicated as a vulnerability gene for bipolar disorder (BD). We aimed to associate genetic variants in the AKT1 gene with subgroups of BD. BD patients from a Swedish cohort (N = 831) were phenotyped in regards to their psychotic episodes according to mood-congruence in depression and manias, and compared to controls (N = 1,496). All participants were genotyped for SNPs in AKT1 previously implicated to have a role: rs3730358, rs1130214 and rs3803300. None of the effects reported in earlier studies were statistically significant, including the association between rs3803300 and BD without any psychotic symptoms, rs3803300 and mood-congruent psychosis, rs3803300 and the combined groups, as well as the association between the haplotypes formed by rs3730358 and rs1130214 and risk for BD. In a Bayesian analysis, all Bayes' Factors using default priors supported the null hypothesis in the replication set by a factor of between 5 and 1300 times. Analysis of genome wide association data did not reveal any association between BD and the AKT1 region. We conclude AKT1 is less likely to be a vulnerability gene in BD.

Lithium for schizophrenia: supporting evidence from a 12-year, nationwide health insurance database and from Akt1-deficient mouse and cellular models

Accumulating evidence suggests AKT1 and DRD2-AKT-GSK3 signaling involvement in schizophrenia. AKT1 activity is also required for lithium, a GSK3 inhibitor, to modulate mood-related behaviors. Notably, GSK3 inhibitor significantly alleviates behavioral deficits in Akt1^−/− female mice, whereas typical/atypical antipsychotics have no effect. In agreement with adjunctive therapy with lithium in treating schizophrenia, our data mining indicated that the average utilization rates of lithium in the Taiwan National Health Insurance Research Database from 2002 to 2013 are 10.9% and 6.63% in inpatients and outpatients with schizophrenia, respectively. Given that lithium is commonly used in clinical practice, it is of great interest to evaluate the effect of lithium on alleviating Akt1-related deficits. Taking advantage of Akt1^+/− mice to mimic genetic deficiency in patients, behavioral impairments were replicated in female Akt1^+/− mice but were alleviated by subchronic lithium treatment for 13 days. Lithium also effectively alleviated the observed reduction in phosphorylated GSK3α/β expression in the brains of Akt1^+/− mice. Furthermore, inhibition of Akt expression using an Akt1/2 inhibitor significantly reduced neurite length in P19 cells and primary hippocampal cell cultures, which was also ameliorated by lithium. Collectively, our findings implied the therapeutic potential of lithium and the importance of the AKT1-GSK3 signaling pathway.

Ribosomal Protein S6 Hypofunction in Postmortem Human Brain Links mTORC1-Dependent Signaling and Schizophrenia

The mechanistic target of rapamycin (also known as mammalian target of rapamycin) (mTOR)-dependent signaling pathway plays an important role in protein synthesis, cell growth, and proliferation, and has been linked to the development of the central nervous system. Recent studies suggest that mTOR signaling pathway dysfunction could be involved in the etiopathogenesis of schizophrenia. The main goal of this study was to evaluate the status of mTOR signaling pathway in postmortem prefrontal cortex (PFC) samples of subjects with schizophrenia. For this purpose, we quantified the protein expression and phosphorylation status of the mTOR downstream effector ribosomal protein S6 as well as other pathway interactors such as Akt and GSK3β. Furthermore, we quantified the status of these proteins in the brain cortex of rats chronically treated with the antipsychotics haloperidol, clozapine, or risperidone. We found a striking decrease in the expression of total S6 and in its active phosphorylated form phospho-S6 (Ser235/236) in the brain of subjects with schizophrenia compared to matched controls. The chronic treatment with the antipsychotics haloperidol and clozapine affected both the expression of GSK3β and the activation of Akt [phospho-Akt (Ser473)] in rat brain cortex, while no changes were observed in S6 and phospho-S6 (Ser235/236) protein expression with any antipsychotic treatment. These findings provide further evidence for the involvement of the mTOR-dependent signaling pathway in schizophrenia and suggest that a hypofunctional S6 may have a role in the etiopathogenesis of this disorder.

NOX2-Dependent Reactive Oxygen Species Regulate Formyl-Peptide Receptor 1-Mediated TrkA Transactivation in SH-SY5Y Cells

Several enzymes are capable of producing reactive oxygen species (ROS), but only NADPH oxidases (NOX) generate ROS as their primary and sole function. In the central nervous system, NOX2 is the major source of ROS, which play important roles in signalling and functions. NOX2 activation requires p47^phox phosphorylation and membrane translocation of cytosolic subunits. We demonstrate that SH-SY5Y cells express p47^phox and that the stimulation of Formyl-Peptide Receptor 1 (FPR1) by N-fMLP induces p47^phox phosphorylation and NOX-dependent superoxide generation. FPR1 is a member of the G protein-coupled receptor (GPCR) family and is able to transphosphorylate several tyrosine kinase receptors (RTKs). This mechanism requires ROS as signalling intermediates and is necessary to share information within the cell. We show that N-fMLP stimulation induces the phosphorylation of cytosolic Y490, Y751, and Y785 residues of the neurotrophin receptor TrkA. These phosphotyrosines provide docking sites for signalling molecules which, in turn, activate Ras/MAPK, PI3K/Akt, and PLC-γ1/PKC intracellular cascades. N-fMLP-induced ROS generation plays a critical role in FPR1-mediated TrkA transactivation. In fact, the blockade of NOX2 functions prevents Y490, Y751, and Y785 phosphorylation, as well as the triggering of downstream signalling cascades. Moreover, we observed that FPR1 stimulation by N-fMLP also improves proliferation, cellular migration, and neurite outgrowth of SH-SY5Y cells.

Molecular Mechanisms Linking ALS/FTD and Psychiatric Disorders, the Potential Effects of Lithium

Altered proteostasis, endoplasmic reticulum (ER) stress, abnormal unfolded protein response (UPR), mitochondrial dysfunction and autophagy impairment are interconnected events, which contribute to the pathogenesis of amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). In recent years, the mood stabilizer lithium was shown to potentially modify ALS/FTD beyond mood disorder-related pathology. The effects of lithium are significant in ALS patients carrying genetic variations in the UNC13 presynaptic protein, which occur in ALS/FTD and psychiatric disorders as well. In the brain, lithium modulates a number of biochemical pathways involved in synaptic plasticity, proteostasis, and neuronal survival. By targeting UPR-related events, namely ER stress, excitotoxicity and autophagy dysfunction, lithium produces plastic effects. These are likely to relate to neuroprotection, which was postulated for mood and motor neuron disorders. In the present manuscript, we try to identify and discuss potential mechanisms through which lithium copes concomitantly with ER stress, UPR and autophagy dysfunctions related to UNC13 synaptic alterations and aberrant RNA and protein processing. This may serve as a paradigm to provide novel insights into the neurobiology of ALS/FTD featuring early psychiatric disturbances.

Putative Mechanisms of Action and Clinical Use of Lithium in Children and Adolescents: A Critical Review

Background:

Lithium is a first-line treatment for bipolar disorder in adults, but its mechanism of action is still far from clear. Furthermore, evidences of its use in pediatric populations are sparse, not only for bipolar disorders, but also for other possible indications.

Objectives:

To provide a synthesis of published data on the possible mechanisms of action of lithium, as well as on its use in pediatric samples, including pharmacokinetics, efficacy, and safety data.

Methods:

Clinical trials in pediatric samples with at least one standardized measure of efficacy/effectiveness were included in this review. We considered: i) randomized and open label trials, ii) combination studies iii) augmentation studies iv) case series including at least 5 patients.

Results:

Different and non-alternative mechanisms of action can explain the clinical efficacy of lithium. Clinical studies in pediatric samples suggest that lithium is effective in managing manic symptoms/episodes of bipolar disorder, both in the acute phase and as maintenance strategy. Efficacy on depressive symptoms/phases of bipolar disorder is much less clear, while studies do not support its use in unipolar depression and severe mood dysregulation. Conversely, it may be effective on aggression in the context of conduct disorder. Other possible indications, with limited published evidence, are the acute attacks in Kleine-Levin syndrome, behavioral symptoms of X-fragile syndrome, and the management of clozapine- or chemotherapy- induced neutropenia. Generally, lithium resulted relatively safe.

Conclusions:

Lithium seems an effective and well-tolerated medication in pediatric bipolar disorder and aggression, while further evidences are needed for other clinical indications.

The cholinergic system in the pathophysiology and treatment of Alzheimer's disease

Cholinergic synapses are ubiquitous in the human central nervous system. Their high density in the thalamus, striatum, limbic system, and neocortex suggest that cholinergic transmission is likely to be critically important for memory, learning, attention and other higher brain functions. Several lines of research suggest additional roles for cholinergic systems in overall brain homeostasis and plasticity. As such, the brain's cholinergic system occupies a central role in ongoing research related to normal cognition and age-related cognitive decline, including dementias such as Alzheimer's disease. The cholinergic hypothesis of Alzheimer's disease centres on the progressive loss of limbic and neocortical cholinergic innervation. Neurofibrillary degeneration in the basal forebrain is believed to be the primary cause for the dysfunction and death of forebrain cholinergic neurons, giving rise to a widespread presynaptic cholinergic denervation. Cholinesterase inhibitors increase the availability of acetylcholine at synapses in the brain and are one of the few drug therapies that have been proven clinically useful in the treatment of Alzheimer's disease dementia, thus validating the cholinergic system as an important therapeutic target in the disease. This review includes an overview of the role of the cholinergic system in cognition and an updated understanding of how cholinergic deficits in Alzheimer's disease interact with other aspects of disease pathophysiology, including plaques composed of amyloid-β proteins. This review also documents the benefits of cholinergic therapies at various stages of Alzheimer's disease and during long-term follow-up as visualized in novel imaging studies. The weight of the evidence supports the continued value of cholinergic drugs as a standard, cornerstone pharmacological approach in Alzheimer's disease, particularly as we look ahead to future combination therapies that address symptoms as well as disease progression.

Classic Prescription, Kai-Xin-San, Ameliorates Alzheimer's Disease as an Effective Multitarget Treatment: From Neurotransmitter to Protein Signaling Pathway

Alzheimer's disease (AD) is a widespread neurodegenerative disease caused by complicated disease-causing factors. Unsatisfactorily, curative effects of approved anti-AD drugs were not good enough due to their actions on single-target, which led to desperate requirements for more effective drug therapies involved in multiple pathomechanisms of AD. The anti-AD effect with multiple action targets of Kai-Xin-San (KXS), a classic prescription initially recorded in Bei Ji Qian Jin Yao Fang and applied in the treatment of dementia for thousands of years, was deciphered with modern biological methods in our study. Aβ_25-35 and D-gal-induced AD rats and Aβ_25-35-induced PC12 cells were applied to establish AD models. KXS could significantly improve cognition impairment by decreasing neurotransmitter loss and enhancing the expression of PI3K/Akt. For the first time, KXS was confirmed to improve the expression of PI3K/Akt by neurotransmitter 5-HT. Thereinto, PI3K/Akt could further inhibit Tau hyperphosphorylation as well as the apoptosis induced by oxidative stress and neuroinflammation. Moreover, all above-mentioned effects were verified and blocked by PI3K inhibitor, LY294002, in Aβ_25-35-induced PC12 cells, suggesting the precise regulative role of KXS in the PI3K/Akt pathway. The utilization and mechanism elaboration of KXS have been proposed and dissected in the combination of animal, molecular, and protein strategies. Our results demonstrated that KXS could ameliorate AD by regulating neurotransmitter and PI3K/Akt signal pathway as an effective multitarget treatment so that the potential value of this classic prescription could be explored from a novel perspective.

sVCAM-1, sICAM-1, TNF-α and IL-6 levels in bipolar disorder type I: Acute, longitudinal and therapeutic implications

OBJECTIVES

To explore the serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular cell adhesion molecule-1 (sICAM-1), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in patients with bipolar disorder (BD), with regard to acute episode characteristics, course of the disorder and treatment.

METHODS

The study group consisted of 83 patients diagnosed with BD type I. The control group consisted of 73 healthy individuals, matched with the study group according to age, gender and body mass index. The serum levels of sVCAM-1, sICAM-1, TNF-α and IL-6 were measured by ELISA.

RESULTS

Compared with healthy controls, significantly elevated levels of IL-6 and sICAM-1 and significantly lower levels of TNF-α and sVCAM-1 were identified in acute and remission phases of BD. The acute serum levels of sVCAM-1 were associated with the type and severity of acute mood symptoms as well as with course of illness characteristics. TNF-α was associated with duration of untreated disorder and type of treatment.

CONCLUSIONS

BD is related to both acute and long-term alterations of immune mediators, including adhesion molecules. The potential immunomodulatory role of pharmacotherapeutic treatment is also to be considered in BD.

Drug discovery for psychiatric disorders using high-content single-cell screening of signaling network responses ex vivo

There is a paucity of efficacious new compounds to treat neuropsychiatric disorders. We present a novel approach to neuropsychiatric drug discovery based on high-content characterization of druggable signaling network responses at the single-cell level in patient-derived lymphocytes ex vivo. Primary T lymphocytes showed functional responses encompassing neuropsychiatric medications and central nervous system ligands at established (e.g., GSK-3β) and emerging (e.g., CrkL) drug targets. Clinical application of the platform to schizophrenia patients over the course of antipsychotic treatment revealed therapeutic targets within the phospholipase Cγ1-calcium signaling pathway. Compound library screening against the target phenotype identified subsets of L-type calcium channel blockers and corticosteroids as novel therapeutically relevant drug classes with corresponding activity in neuronal cells. The screening results were validated by predicting in vivo efficacy in an independent schizophrenia cohort. The approach has the potential to discern new drug targets and accelerate drug discovery and personalized medicine for neuropsychiatric conditions.

Regulation of the Neuroligin-1 Gene by Clock Transcription Factors

NEUROLIGIN-1 (NLGN1) is a postsynaptic adhesion molecule involved in the regulation of glutamatergic transmission. It has been associated with several features of sleep and psychiatric disorders. Our previous work suggested that transcription of the Nlgn1 gene could be regulated by the transcription factors CLOCK and BMAL1 because they bind to the Nlgn1 gene promoter in vivo. However, whether CLOCK/BMAL1 can directly activate Nlgn1 transcription is not yet known. We thus aimed to verify whether CLOCK/BMAL1, as well as their homologs NPAS2 and BMAL2, can activate transcription via the Nlgn1 promoter by using luciferase assays in COS-7 cells. We also investigated how Nlgn1 expression was affected in Clock mutant mice. Our results show transcriptional activation in vitro mediated by CLOCK/BMAL1 and by combinations with their homologs NPAS2 and BMAL2. Moreover, CLOCK/BMAL1 activation via the Nlgn1 gene fragment was repressed by GSK3β. In vivo, Nlgn1 mRNA expression was significantly modified in the forebrain of Clock mutant mice in a transcript variant-dependent manner. However, no significant change in NLGN1 protein level was observed in Clock mutant mice. These findings will increase knowledge about the transcriptional regulation of Nlgn1 and the relationship between circadian rhythms, mental health, and sleep.

Rho-kinase inhibition has antidepressant-like efficacy and expedites dendritic spine pruning in adolescent mice

Adolescence represents a critical period of neurodevelopment, defined by structural and synaptic pruning within the prefrontal cortex. While characteristic of typical development, this structural instability may open a window of vulnerability to developing neuropsychiatric disorders, including depression. Thus, therapeutic interventions that support or expedite neural remodeling in adolescence may be advantageous. Here, we inhibited the neuronally-expressed cytoskeletal regulatory factor Rho-kinase (ROCK), focusing primarily on the clinically-viable ROCK inhibitor fasudil. ROCK inhibition had rapid antidepressant-like effects in adolescent mice, and its efficacy was comparable to ketamine and fluoxetine. It also modified levels of the antidepressant-related signaling factors, tropomyosin/tyrosine receptor kinase B and Akt, as well as the postsynaptic marker PSD-95, in the ventromedial prefrontal cortex (vmPFC). Meanwhile, adolescent-typical dendritic spine pruning on excitatory pyramidal neurons in the vmPFC was expedited. Further, vmPFC-specific shRNA-mediated reduction of ROCK2, the dominant ROCK isoform in the brain, had antidepressant-like consequences. We cautiously suggest that ROCK inhibitors may have therapeutic potential for adolescent-onset depression.

Primary Cilia-An Underexplored Topic in Major Mental Illness

Though much progress has been made in recent years towards understanding the function and physiology of primary cilia, they remain a somewhat elusive organelle. Some studies have explored the role of primary cilia in the developing nervous system, and their dysfunction has been linked with several neurosensory deficits. Yet, very little has been written on their potential role in psychiatric disorders. This article provides an overview of some of the functions of primary cilia in signalling pathways, and demonstrates that they are a worthy candidate in psychiatric research. The links between primary cilia and major mental illness have been demonstrated to exist at several levels, spanning genetics, signalling pathways, and pharmacology as well as cell division and migration. The primary focus of this review is on the sensory role of the primary cilium and the neurodevelopmental hypothesis of psychiatric disease. As such, the primary cilium is demonstrated to be a key link between the cellular environment and cell behaviour, and hence of key importance in the considerations of the nature and nurture debate in psychiatric research.

Roles of PI3K/AKT/GSK3 Pathway Involved in Psychiatric Illnesses

Psychiatric illnesses may be qualified to the cellular impairments of the function for survival or death in neurons, which may consequently appear as abnormalities in the neuroplasticity. The molecular mechanism has not been well understood, however, it seems that PI3K, AKT, GSK3, and their downstream molecules have crucial roles in the pathogenesis. Through transducing cell surviving signal, the PI3K/AKT/GSK3 pathway may organize an intracellular central network for the action of the synaptic neuroplasticity. In addition, the pathways may also regulate cell proliferation, cell migration, and apoptosis. Several lines of evidence have supported a role for this signaling network underlying the development and treatment for psychiatric illnesses. Indeed, the discovery of molecular biochemical phenotypes would represent a breakthrough in the research for effective treatment. In this review, we summarize advances on the involvement of the PI3K/AKT/GSK3 pathways in cell signaling of neuronal cells. This study may provide novel insights on the mechanism of mental disorder involved in psychiatric illnesses and would open future opportunity for contributions suggesting new targets for diagnostic and/or therapeutic procedures.

Structural variation during dog domestication: insights from gray wolf and dhole genomes

Several processes like phenotypic evolution, disease susceptibility and environmental adaptations, which fashion the domestication of animals, are largely attributable to structural variations (SVs) in the genome. Here, we present high-quality draft genomes of the gray wolf (Canis lupus) and dhole (Cuon alpinus) with scaffold N50 of 6.04 Mb and 3.96 Mb, respectively. Sequence alignment comprising genomes of three canid species reveals SVs specific to the dog, particularly 16 315 insertions, 2565 deletions, 443 repeats, 16 inversions and 15 translocations. Functional annotation of the dog SVs associated with genes indicates their enrichments in energy metabolisms, neurological processes and immune systems. Interestingly, we identify and verify at population level an insertion fully covering a copy of the AKR1B1 (Aldo-Keto Reductase Family 1 Member B) transcript. Transcriptome analysis reveals a high level of expression of the new AKR1B1 copy in the small intestine and liver, implying an increase in de novo fatty acid synthesis and antioxidant ability in dog compared to gray wolf, likely in response to dietary shifts during the agricultural revolution. For the first time, we report a comprehensive analysis of the evolutionary dynamics of SVs during the domestication step of dogs. Our findings demonstrate that retroposition can birth new genes to facilitate domestication, and affirm the importance of large-scale genomic variants in domestication studies.

Unravelling the GSK3β-related genotypic interaction network influencing hippocampal volume in recurrent major depressive disorder

OBJECTIVE

Glycogen synthase kinase 3β (GSK3β) has been implicated in mood disorders. We previously reported associations between a GSK3β polymorphism and hippocampal volume in major depressive disorder (MDD). We then reported similar associations for a subset of GSK3β-regulated genes. We now investigate an algorithm-derived comprehensive list of genes encoding proteins that directly interact with GSK3β to identify a genotypic network influencing hippocampal volume in MDD.

PARTICIPANTS AND METHODS

We used discovery (N=141) and replication (N=77) recurrent MDD samples. Our gene list was generated from the NetworKIN database. Hippocampal measures were derived using an optimized Freesurfer protocol. We identified interacting single nucleotide polymorphisms using the machine learning algorithm Random Forest and verified interactions using likelihood ratio tests between nested linear regression models.

RESULTS

The discovery sample showed multiple two-single nucleotide polymorphism interactions with hippocampal volume. The replication sample showed a replicable interaction (likelihood ratio test: P=0.0088, replication sample; P=0.017, discovery sample; Stouffer's combined P=0.0007) between genes associated previously with endoplasmic reticulum stress, calcium regulation and histone modifications.

CONCLUSION

Our results provide genetic evidence supporting associations between hippocampal volume and MDD, which may reflect underlying cellular stress responses. Our study provides evidence of biological mechanisms that should be further explored in the search for disease-modifying therapeutic targets for depression.

Targeting GSK3 signaling as a potential therapy of neurodegenerative diseases and aging

INTRODUCTION

Glycogen synthase kinase 3 (GSK3) is at the center of cellular signaling and controls various aspects of brain functions, including development of the nervous system, neuronal plasticity and onset of neurodegenerative disorders. Areas covered: In this review, recent efforts in elucidating the roles of GSK3 in neuronal plasticity and development of brain pathologies; Alzheimer's and Parkinson's disease, schizophrenia, and age-related neurodegeneration are described. The effect of microglia and astrocytes on development of the pathological states is also discussed. Expert opinion: GSK3β and its signaling pathway partners hold great promise as therapeutic target(s) for a multitude of neurological disorders. Activity of the kinase is often elevated in brain disorders. However, due to the wide range of GSK3 cellular targets, global inhibition of the kinase leads to severe side-effects and GSK3 inhibitors rarely reach Phase-2 clinical trials. Thus, a selective modulation of a specific cellular pool of GSK3 or specific down- or upstream partners of the kinase might provide more efficient anti-neurodegenerative therapies.

Subchronic administration of creatine produces antidepressant-like effect by modulating hippocampal signaling pathway mediated by FNDC5/BDNF/Akt in mice

Creatine has been shown to play a significant role in the pathophysiology and treatment of major depressive disorder (MDD) in preclinical and clinical studies. However, the biological mechanisms underlying its antidepressant effect is still not fully elucidated. This study investigated the effect of creatine (p.o.) administered for 21 days in the behavior of mice submitted to tail suspension test (TST), a predictive test of antidepressant activity. Creatine reduced the immobility time in the TST (1-10 mg/kg), without affecting locomotor activity, a finding consistent with an antidepressant profile. Creatine administration increased the ubiquitous creatine kinase (uCK) and creatine kinase brain isoform (CK-B) mRNA in the hippocampus of mice. Taking into account that PGC-1α induces FNDC5/irisin expression mediating BDNF-dependent neuroplasticity, the effect of creatine administration (1 mg/kg, p. o.) on the hippocampal PGC-1α, FNDC5 and BDNF gene expression was investigated. Creatine treatment increased PGC-1α, FNDC5 and BDNF mRNA in the hippocampus as well as BDNF immunocontent. The involvement of BDNF downstream intracellular signaling pathway mediated by Akt, proapoptotic proteins BAX and BAD and antiapoptotic proteins Bcl2 and Bcl-xL was also investigated following creatine treatment. Creatine increased Akt phosphorylation (Ser 473), and Bcl2 mRNA and protein levels, and Bcl-xL mRNA, whereas BAD mRNA was decreased following creatine administration in the hippocampus. Altogether these results indicate that creatine antidepressant-like effect may be dependent on Akt activation and increased expression of the neuroprotective proteins in the hippocampus of mice. The obtained data reinforce the antidepressant property of creatine and highlight the role of these molecular targets in the pathophysiology of MDD.

PET imaging of dopamine-D2 receptor internalization in schizophrenia

Recent genetic, molecular and post-mortem studies suggest impaired dopamine (DA)-D2 receptor (D2R) trafficking in patients with schizophrenia (SZ). Imaging and preclinical studies have shown agonist-induced D2R internalization can be imaged with positron emission tomography (PET) using D2R radiotracers combined with psychostimulant challenge. This is feasible if radiotracer binding is measured when postchallenge DA levels have returned to baseline, following the initial competition phase between DA and radiotracer for binding to D2R. Here we used 'late-phase' imaging after challenge to test the hypothesis that impaired D2R internalization in SZ leads to blunted late-phase displacement, or a faster return to baseline, in patients compared with healthy controls (HCs). We imaged 10 patients with SZ and 9 HCs with PET and [¹¹C]raclopride at baseline and two times (3-5 and 6-10 h) following 0.5 mg kg^-1 dextroamphetamine. We measured binding potential relative to non-displaceable compartment (BP_ND) and derived percent reduction from baseline (ΔBP_ND) for each postamphetamine scan. To test the hypothesis that time course of return of striatal BP_ND to baseline differed between SZ and HCs, we implemented a linear model with ΔBP_ND as dependent variable, time after amphetamine as repeated measure and time after amphetamine and diagnostic group as fixed effects. Neither diagnostic group nor interaction of diagnostic group-by-time after amphetamine significantly affected striatal ΔBP_ND (F=1.38, P=0.26; F=0.51, P=0.61). These results show similar pattern of return of BP_ND to baseline as a function of time in patients with SZ and HC, suggesting that striatal D2R internalization as measured by our imaging paradigm is normal in patients with SZ.

Increased platelet glycogen sysnthase kinase 3beta in first-episode psychosis

Past studies have linked intracellular pathways related to psychotic disorders to the GSK3B enzyme. This study aimed to investigate GSK3B protein expression and phosphorylation in drug-naïve first-episode psychosis patients (n=43) at baseline and following symptom remission, and in healthy controls (n=77). At baseline GSK3B total level was higher in patients (p<0.001). In schizophrenia spectrum patients (n=25) GSK3B total and phosphorylated levels were higher than in controls and patients with other non-affective psychotic disorders (n=18) (p<0.001; p=0.027; p=0.05 respectively). No enzyme changes were found after clinical remission. The implication of this finding for the biology of psychoses warrants further studies to clarify whether increased GSK3B may be useful as a biomarker for psychosis in general, and schizophrenia in particular.

Environmental Enrichment and Social Isolation Mediate Neuroplasticity of Medium Spiny Neurons through the GSK3 Pathway

Resilience and vulnerability to neuropsychiatric disorders are linked to molecular changes underlying excitability that are still poorly understood. Here, we identify glycogen-synthase kinase 3β (GSK3β) and voltage-gated Na+ channel Nav1.6 as regulators of neuroplasticity induced by environmentally enriched (EC) or isolated (IC) conditions-models for resilience and vulnerability. Transcriptomic studies in the nucleus accumbens from EC and IC rats predicted low levels of GSK3β and SCN8A mRNA as a protective phenotype associated with reduced excitability in medium spiny neurons (MSNs). In vivo genetic manipulations demonstrate that GSK3β and Nav1.6 are molecular determinants of MSN excitability and that silencing of GSK3β prevents maladaptive plasticity of IC MSNs. In vitro studies reveal direct interaction of GSK3β with Nav1.6 and phosphorylation at Nav1.6T1936 by GSK3β. A GSK3β-Nav1.6T1936 competing peptide reduces MSNs excitability in IC, but not EC rats. These results identify GSK3β regulation of Nav1.6 as a biosignature of MSNs maladaptive plasticity.

Association of Protein Kinase B (AKT) DNA Hypermethylation with Maintenance Atypical Antipsychotic Treatment in Patients with Bipolar Disorder

STUDY OBJECTIVE

Atypical antipsychotics cause insulin resistance that leads to an increased risk of diabetes mellitus and cardiovascular disease. Skeletal muscle is the primary tissue for uptake of glucose, and its dysfunction is considered one of the primary defects in the development of insulin resistance. Protein kinase B (AKT) plays an important role in overall skeletal muscle health and glucose uptake into the muscle. The objective of this study was to measure AKT isoform-specific gene methylation differences in the skeletal muscle of patients with bipolar disorder treated with atypical antipsychotic or mood stabilizer maintenance therapy.

DESIGN

Cross-sectional observational study.

SETTING

Clinical research services center at an academic center.

PATIENTS

Thirty patients with a confirmed diagnosis of bipolar disorder who were treated with either an atypical antipsychotic (16 patients) or mood stabilizer (14 patients) at a consistent dose for at least 3 months.

INTERVENTIONS

A fasting skeletal muscle biopsy was performed in the vastus lateralis in each patient. Patients also underwent fasting blood sample collection and a standard 75-g oral glucose tolerance test.

MEASUREMENTS AND MAIN RESULTS

Skeletal muscle DNA methylation near the promoter region for three genes, AKT1, AKT2, and AKT3, was measured by methylation-sensitive high-resolution melting. Gene methylation was analyzed based on atypical antipsychotic versus mood stabilizer maintenance therapy. Associations between gene methylation, insulin resistance, and glucose tolerance were also analyzed. In patients treated with atypical antipsychotics, AKT1 and AKT2 methylation was increased compared with patients treated with mood stabilizers (p=0.03 and p=0.02, respectively). In addition, for patients receiving atypical antipsychotics, a positive trend for AKT2 hypermethylation with increasing insulin resistance was observed, whereas for patients receiving mood stabilizers, a trend for decreased AKT2 methylation with increasing insulin resistance was observed.

CONCLUSION

Overall, our findings suggest that the AKT gene is differentially methylated in the skeletal muscle of patients taking atypical antipsychotics or mood stabilizer maintenance therapy. These results may direct future approaches to reduce the harmful adverse effects of atypical antipsychotic treatment.

Antidepressant-Like Effects of Vaccinium bracteatum in Chronic Restraint Stress Mice: Functional Actions and Mechanism Explorations

The fruit of Vaccinium bracteatum Thunb. (VBF) is commonly known as the oriental blueberry in Korea. The aim of this study was to evaluate the antidepressant-like effects of water VBF extract (VBFW) in a mouse model of chronic restraint stress (CRS) and to identify the underlying mechanisms of its action. The behavioral effects of VBFW were assessed in the forced swim test (FST) and open field test (OFT). The levels of serum corticosterone (CORT), brain monoamines, in addition to the extracellular signal-regulated kinases (ERKs)/protein kinase B (Akt) signaling pathway were evaluated. VBFW treatment significantly reduced the immobility time and increased swimming time in FST without altering the locomotor activity in unstressed mice. Furthermore, CRS mice treated with VBFW exhibited a significantly decreased immobility time in FST and serum CORT, increased locomotor activity in OFT, and enhanced brain monoamine neurotransmitters. Similarly, VBFW significantly upregulated the ERKs/Akt signaling pathway in the hippocampus and PFC. In addition, VBFW may reverse CORT-induced cell death by enhancing cyclic AMP-responsive element-binding protein expression through the up-regulation of ERKs/Akt signaling pathways. In addition, VBFW showed the strong antagonistic effect of the 5-HT[Formula: see text] receptor by inhibiting 5-HT-induced intracellular Ca[Formula: see text] and ERK1/2 phosphorylation. Our study provides evidence that antidepressant-like effects of VBFW might be mediated by the regulation of monoaminergic systems and glucocorticoids, which is possibly associated with neuroprotective effects and antagonism of 5-HT[Formula: see text] receptor.

Behavioral and biochemical sensitivity to low doses of ketamine: Influence of estrous cycle in C57BL/6 mice

RATIONALE

Low-dose ketamine is a rapid-acting antidepressant, to which female rodents are more sensitive as compared to males. However, the mechanism mediating this sex difference in ketamine sensitivity remains elusive.

OBJECTIVES

We sought to determine whether male and female mice differ in their behavioral sensitivity to low doses of ketamine, and uncover how ovarian hormones influence females' ketamine sensitivity. We also aimed to uncover some of the molecular mechanism(s) in mood-related brain regions that mediate sex differences in ketamine antidepressant effects.

METHODS

Male and female mice (freely-cycling, diestrus 1 [D1], proestrus [Pro], or D1 treated with an estrogen receptor (ER) α, ERβ, or progesterone receptor (PR) agonist) received ketamine (0, 1.5, or 3 mg/kg, intraperitoneally) and were tested in the forced swim test (FST) 30 min later. Ketamine's influence over synaptic plasticity markers in the prefrontal cortex (PFC) and hippocampus (HPC) of males, D1, and Pro females was quantified by Western blot 1 h post-treatment.

RESULTS

Males, freely cycling females, D1 and Pro females exhibited antidepressant-like responses to 3 mg/kg ketamine. Pro females were the only group where ketamine exhibited an antidepressant effect at 1.5 mg/kg. D1 females treated with an agonist for ERα or ERβ exhibited an antidepressant-like response to 1.5 mg/kg ketamine. Ketamine (3 mg/kg) increased synaptic plasticity-related proteins in the PFC and HPC of males, D1, and Pro females. Yet, Pro females exhibited an increase in p-Akt and p-CaMKIIα in response to 1.5 and 3 mg/kg ketamine.

CONCLUSION

Our results indicate that females' enhanced sensitivity to ketamine during Pro is likely mediated through estradiol acting on ERα and ERβ, leading to greater activation of synaptic plasticity-related kinases within the PFC and HPC.

Synthesis of benzimidazole-linked-1,3,4-oxadiazole carboxamides as GSK-3β inhibitors with in vivo antidepressant activity

Recent findings of potential implications of glycogen synthase kinase-3β (GSK-3β) dysfunction in psychiatric disorders like depression, have increased focus for development of GSK-3β inhibitors with possible anti-depressant activity. Keeping this in view, we synthesized a series of benzimidazole-linked-1,3,4-oxadiazole carboxamides and evaluated them for in vitro GSK-3β inhibition. Active compounds were investigated for in vivo antidepressant activity in Wistar rats. Docking studies of active compounds have also been performed. Among nineteen compounds synthesized, compounds 7a, 7r, 7j, and 7d exhibited significant potency against GSK-3β in sub-micromolar range with IC₅₀ values of 0.13 μM, 0.14 μM, 0.20 μM, 0.22 μM respectively and significantly reduced immobility time (antidepressant-like activity) in rats compared to control group. Docking study showed key interactions of these compounds with GSK-3β. These compounds may thus serve as valuable candidates for subsequent development of effective drugs against depression and related disorders.

Cotinine: A Therapy for Memory Extinction in Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a mental disorder that may develop after exposure to exceptionally threatening or unescapable horrifying events. Actual therapies fail to alleviate the emotional suffering and cognitive impairment associated with this disorder, mostly because they are ineffective in treating the failure to extinguish trauma memories in a great percentage of those affected. In this review, current behavioral, cellular, and molecular evidence supporting the use of cotinine for treating PTSD are reviewed. The role of the positive modulation by cotinine of the nicotinic acetylcholine receptors (nAChRs) and their downstream effectors, the protection of astroglia, and the inhibition of microglia in the PTSD brain are also discussed.

Ursolic acid affords antidepressant-like effects in mice through the activation of PKA, PKC, CAMK-II and MEK1/2

BACKGROUND

Ursolic acid has been shown to display antidepressant-like effects in mice through the modulation of monoaminergic systems. In this study, we sought to investigate the involvement of signaling pathways on the antidepressant-like effects of ursolic acid.

METHODS

Mice were treated orally with ursolic acid (0.1mg/kg) and, 45min later they received the followings inhibitors by intracerebroventricular route: H-89 (PKA inhibitor, 1μg/mouse), KN-62 (CAMK-II inhibitor, 1μg/mouse), chelerythrine (PKC inhibitor, 1μg/mouse), U0126 (MEK1/2 inhibitor, 5μg/mouse), PD98059 (MEK1/2 inhibitor, 5μg/mouse), wortmannin (PI3K irreversible inhibitor, 0.1μg/mouse) or LY294002 (PI3K inhibitor, 10 nmol/mouse). Immobility time of mice was registered in the tail suspension test (TST).

RESULTS

The anti-immobility effect of ursolic acid in the TST was abolished by the treatment of mice with H-89, KN-62, chelerythrine, U0126 or PD98059, but not with wortmannin or LY294002.

CONCLUSIONS

These results suggest that activation of PKA, PKC, CAMK-II, MEK1/2 may underlie the antidepressant-like effects of ursolic acid.

Correlation of DRD2 mRNA expression levels with deficit syndrome severity in chronic schizophrenia patients receiving clozapine treatment

Schizophrenia is a complex, severe, chronic psychiatric disorder, and the associated deficit syndrome is widely regarded as an important clinical aspect of schizophrenia. This study analyzed the relationship of deficit syndrome severity with the mRNA levels of members of signaling pathways that associate with the pathophysiology of schizophrenia, including the dopamine D2 receptor (DRD2), protein kinase B (AKT1), and phosphoinositide-3 kinase (PI3KCB), in peripheral blood leukocytes (PBLs) of 20 healthy controls and 19 chronic schizophrenia patients with long-term clozapine treatment. The DRD2 expression levels in chronic schizophrenia group were statistically higher than those in controls (t=2.168, p=0.037). Moreover, in chronic schizophrenia group, correlations were observed between the expression levels of DRD2 and PI3KCB (r=0.771, p<0.001), DRD2 and AKT1 (r=0.592, p=0.008), and PI3KCB and AKT1 (r=0.562, p=0.012) and between the DRD2 mRNA levels and the Proxy for the Deficit Syndrome score (r=0.511, p=0.025). In control group, the correlation between PI3KCB expression levels and DRD2 expression levels was only observed (r=0.782, p<0.001). In conclusion, a correlation was observed between increased deficit syndrome severity and elevated expression levels of DRD2 in PBLs of chronic schizophrenia patients receiving long-term clozapine treatment.

Lysine Deacetylation by HDAC6 Regulates the Kinase Activity of AKT in Human Neural Progenitor Cells

The AKT family of serine-threonine kinases functions downstream of phosphatidylinositol 3-kinase (PI3K) to transmit signals by direct phosphorylation of a number of targets, including the mammalian target of rapamycin (mTOR), glycogen synthase kinase 3β (GSK3β), and β-catenin. AKT binds to phosphatidylinositol (3,4,5)-triphosphate (PIP₃) generated by PI3K activation, which results in its membrane localization and subsequent activation through phosphorylation by phosphoinositide-dependent protein kinase 1 (PDK1). Together, the PI3K-AKT signaling pathway plays pivotal roles in many cellular systems, including in the central nervous system where it governs both neurodevelopment and neuroplasticity. Recently, lysine residues (Lys¹⁴ and Lys²⁰) on AKT, located within its pleckstrin homology (PH) domain that binds to membrane-bound PIP₃, have been found to be acetylated under certain cellular contexts in various cancer cell lines. These acetylation modifications are removed by the enzymatic action of the class III lysine deacetylases, SIRT1 and SIRT2, of the sirtuin family. The extent to which reversible acetylation regulates AKT function in other cell types remains poorly understood. We report here that AKT kinase activity is modulated by a class IIb lysine deacetylase, histone deacetylase 6 (HDAC6), in human neural progenitor cells (NPCs). We find that HDAC6 and AKT physically interact with each other in the neuronal cells, and in the presence of selective HDAC6 inhibition, AKT is acetylated at Lys¹⁶³ and Lys³⁷⁷ located in the kinase domain, two novel sites distinct from the acetylation sites in the PH-domain modulated by the sirtuins. Measurement of the functional effect of HDAC6 inhibition on AKT revealed decreased binding to PIP₃, a correlated decrease in AKT kinase activity, decreased phosphorylation of Ser⁵⁵² on β-catenin, and modulation of neuronal differentiation trajectories. Taken together, our studies implicate the deacetylase activity of HDAC6 as a novel regulator of AKT signaling and point to novel mechanisms for regulating AKT activity with small-molecule inhibitors of HDAC6 currently under clinical development.

Targeted Interneuron Depletion in the Dorsal Striatum Produces Autism-like Behavioral Abnormalities in Male but Not Female Mice

BACKGROUND

Interneuronal pathology is implicated in many neuropsychiatric disorders, including autism spectrum disorder (ASD) and Tourette syndrome (TS). Interneurons of the striatum, including the parvalbumin-expressing fast-spiking interneurons (FSIs) and the large cholinergic interneurons (CINs), are affected in patients with TS and in preclinical models of both ASD and TS.

METHODS

To test the causal importance of these neuronal abnormalities, we recapitulated them in vivo in developmentally normal mice using a combination transgenic-viral strategy for targeted toxin-mediated ablation.

RESULTS

We found that conjoint ~50% depletion of FSIs and CINs in the dorsal striatum of male mice produces spontaneous stereotypy and marked deficits in social interaction. Strikingly, these behavioral effects are not seen in female mice; because ASD and TS have a marked male predominance, this observation reinforces the potential relevance of the finding to human disease. Neither of these effects is seen when only one or the other interneuronal population is depleted; ablation of both is required. Depletion of FSIs, but not of CINs, also produces anxiety-like behavior, as has been described previously. Behavioral pathology in male mice after conjoint FSI and CIN depletion is accompanied by increases in activity-dependent signaling in the dorsal striatum; these alterations were not observed after disruption of only one interneuron type or in doubly depleted female mice.

CONCLUSIONS

These data indicate that disruption of CIN and FSI interneurons in the dorsal striatum is sufficient to produce network and behavioral changes of potential relevance to ASD, in a sexually dimorphic manner.