Hippocampal and prefrontal cortical NMDA receptors mediate the interactive effects of olanzapine and lithium in memory retention in rats: the involvement of CAMKII-CREB signaling pathways

RATIONALE

Treatment of bipolar disorder (BPD) with lithium and olanzapine concurrent administration is a major medicine issue with the elusive neurobiological mechanisms underlying the cognitive function.

OBJECTIVE

To clarify the precise mechanisms involved, the possible role of the hippocampus (HPC) and prefrontal cortical (PFC) NMDA receptors and CAMKII-CREB signaling pathway in the interactive effects of lithium and olanzapine in memory consolidation was evaluated. The dorsal hippocampal CA1 regions of adult male Wistar rats were bilaterally cannulated and a step-through inhibitory avoidance apparatus was used to assess memory consolidation. The changes in p-CAMKII/CAMKII and p-CREB/CREB ratio in the HPC and the PFC were measured by Western blot analysis.

RESULTS

Post-training administration of lithium (20, 30, and 40 mg/kg, i.p.) dose-dependently decreased memory consolidation whereas post-training administration olanzapine (2 and 5 mg/kg, i.p.) increased memory consolidation. Post-training administration of certain doses of olanzapine (1, 2, and 5 mg/kg, i.p.) dose-dependently improved lithium-induced memory impairment. Post-training administration of ineffective doses of the NMDA (10-5 and 10-4 μg/rat, intra-CA1) plus an ineffective dose of olanzapine (1 mg/kg, i.p.) dose-dependently improved the lithium-induced memory impairment. Post-training microinjection of ineffective doses of the NMDA (10-5 and 10-4 μg/rat, intra-CA1) dose-dependently potentiated the memory improvement induced by olanzapine (1 mg/kg, i.p.) on lithium-induced memory impairment which was associated with the enhancement of the levels of p-CAMKII and p-CREB in the HPC and the PFC. Post-training microinjection of ineffective doses of the noncompetitive NMDA receptor antagonist, MK-801 (0.0625 and 0.0125 μg/rat, intra-CA1), dose-dependently decreased the memory improvement induced by olanzapine (5 mg/kg, i.p.) on lithium-induced memory impairment which was related to the reduced levels of HPC and PFC CAMKII-CREB.

CONCLUSION

The results strongly revealed that there is a functional interaction among lithium and olanzapine through the HPC and the PFC NMDA receptor mechanism in memory consolidation which is mediated with the CAMKII-CREB signaling pathway.

Case Studies in Neuroscience: Lack of inhibitory synaptic plasticity in the substantia nigra pars reticulata of a patient with lithium-induced tremor

Tremor is a well-known side effect from many psychiatric medications, including lithium and dopamine antagonists. In patients whose psychiatric symptoms are stabilized and only respond to certain medications, deep brain stimulation may offer relief of the consequent motor complications. We report the case of an elderly male with disabling tremor related to lithium therapy for bipolar affective disorder, who was subsequently treated with deep brain stimulation. In this patient, we obtained recordings from the substantia nigra pars reticulata and performed a high-frequency stimulation protocol that robustly elicits long-term potentiation (LTP)-like changes in patients with Parkinson's disease. We hypothesized that in this patient, who did not have Parkinson's disease, the levels of inhibitory plasticity would be much greater. However, we found an unanticipated lack of plasticity in the patient with lithium-induced tremor, compared with two de novo control patients with Parkinson's disease. This patient was successfully treated with deep brain stimulation in the vicinity of the ventral oral posterior nucleus, an area of the thalamus that receives inputs from the basal ganglia. We postulate that the lithium-induced blockade of LTP may bring about motor complications such as tremor while simultaneously contributing to the therapeutic mechanism for treating the symptoms of psychiatric disorders such as bipolar affective disorder.NEW & NOTEWORTHY Use of a dual-microelectrode technique enabled us to compare long-term potentiation (LTP)-like changes in a patient with lithium-induced tremor to that of patients with Parkinson's disease. This study corroborated the findings in rodent brain slices that chronic lithium treatment may block LTP. Whereas a deficit in LTP may underlie the therapeutic mechanism for treating psychiatric disorders such as bipolar affective disorder, it may simultaneously contribute to consequent appearance of tremor.

cAMP Response Element-Binding Protein (CREB): A Possible Signaling Molecule Link in the Pathophysiology of Schizophrenia

Dopamine is a brain neurotransmitter involved in the pathology of schizophrenia. The dopamine hypothesis states that, in schizophrenia, dopaminergic signal transduction is hyperactive. The cAMP-response element binding protein (CREB) is an intracellular protein that regulates the expression of genes that are important in dopaminergic neurons. Dopamine affects the phosphorylation of CREB via G protein-coupled receptors. Neurotrophins, such as brain derived growth factor (BDNF), are critical regulators during neurodevelopment and synaptic plasticity. The CREB is one of the major regulators of neurotrophin responses since phosphorylated CREB binds to a specific sequence in the promoter of BDNF and regulates its transcription. Moreover, susceptibility genes associated with schizophrenia also target and stimulate the activity of CREB. Abnormalities of CREB expression is observed in the brain of individuals suffering from schizophrenia, and two variants (-933T to C and -413G to A) were found only in schizophrenic patients. The CREB was also involved in the therapy of animal models of schizophrenia. Collectively, these findings suggest a link between CREB and the pathophysiology of schizophrenia. This review provides an overview of CREB structure, expression, and biological functions in the brain and its interaction with dopamine signaling, neurotrophins, and susceptibility genes for schizophrenia. Animal models in which CREB function is modulated, by either overexpression of the protein or knocked down through gene deletion/mutation, implicating CREB in schizophrenia and antipsychotic drugs efficacy are also discussed. Targeting research and drug development on CREB could potentially accelerate the development of novel medications against schizophrenia.

Lithium, Stress, and Resilience in Bipolar Disorder: Deciphering this key homeostatic synaptic plasticity regulator

BACKGROUND

Lithium is the lightest metal and the only mood stabilizer that has been used for over half a century for the treatment of bipolar disorder (BD). As a small ion, lithium is omnipresent, and consequently, its molecular mechanisms and targets are widespread. Currently, lithium is a crucial pharmacotherapy for the treatment of acute mood episodes, prophylactic therapy, and suicide prevention in BD. Besides, lithium blood level is the most widely used biomarker in clinical psychiatry. The concept of stress in BD characterizes short- and long-term deleterious effects at multiple levels (from genes to behaviors) and the ability to establish homeostatic regulatory mechanisms to either prevent or reverse these effects. Within this concept, lithium has consistently shown anti-stress effects, by normalizing components across several levels associated with BD-induced impairments in cellular resilience and plasticity.

METHODS

A literature search for biomarkers associated with lithium effects at multiple targets, with a particular focus on those related to clinical outcomes was performed. An extensive search of the published literature using PubMed, Medline and Google Scholar was performed. Example search terms included lithium, plasticity, stress, efficacy, and neuroimaging. Articles determined by the author to focus on lithium's impact on neural plasticity markers (central and periphery) and clinical outcomes were examined in greater depth. Relevant papers were evaluated, selected and included in this review.

RESULTS

Lithium induces neurotrophic and neuroprotective effects in a wide range of preclinical and translational models. Lithium's neurotrophic effects are related to the enhancement of cellular proliferation, differentiation, growth, and regeneration, whereas its neuroprotective effects limit the progression of neuronal atrophy or cell death following the onset of BD. Lithium's neurotrophic and neuroprotective effects seem most pronounced in the presence of pathology, which again supports its pivotal role as an active homeostatic regulator.

LIMITATIONS

Few studies associated with clinical outcomes. Due to space limitations, the author was unable to detail all findings, in special those originated from preclinical studies.

CONCLUSIONS

These results support a potential role for biomarkers involved in neuroprotection and activation of plasticity pathways in lithium's clinical response. Evidence supporting this model comes from results evaluating macroscopic and microscopic brain structure as well neurochemical findings in vivo from cellular to sub-synaptic (molecules and intracellular signaling) compartments using central and peripheral biomarkers. Challenges to precisely decipher lithium's biological mechanisms involved in its therapeutic profile include the complex nature of the illness and clinical subtypes, family history and comorbid conditions. In the context of personalized medicine, it is necessary to validate predictive biomarkers of response to lithium by designing longitudinal clinical studies during mood episodes and associated clinical dimensions in BD.

Repeated olanzapine treatment mitigates PTSD like symptoms in rats with changes in cell signaling factors

Post Traumatic Stress Disorder is an anxiety disorder with prolonged distortion of rational behavior. In this study, we report the preclinical potential of olanzapine (OLZ) in the treatment of PTSD. Since the atypical antipsychotics have modulating effects on cell protective and destructive factors, we tested the effects of OLZ in PTSD regarding these cell modulating factors. Rats, when subjected to stress-restress (SRS) model of PTSD, showed a derangement in cell protective factors like the decline in BDNF, ERK, and CREB. While the adversarial factors like caspase-3 were enhanced. Four weeks treatment with OLZ at doses of 1 and 10 mg/kg significantly mitigated the SRS-induced derangement related to PTSD. OLZ at doses of 1 and 10 mg/kg enhanced BDNF, ERK and CREB levels which were reduced by SRS in PTSD animals. Further, at the fore mentioned doses it also inhibited the elevation of caspase-3 a downstream apoptotic factor. Besides, OLZ also showed mitigation in behavioral alterations related to anxiety and memory brought about by PTSD. These effects of OLZ were comparable to that of paroxetine a clinically approved drug for PTSD in terms of biochemical and behavioral assessments indicating its anti-PTSD potential.

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

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

Bipolar Disorder and Cognitive Dysfunction: A Complex Link

The aim of this article was to describe the current evidence regarding phenomenon of cognitive functioning and dementia in bipolar disorder (BD). Cochrane Library and PubMed searches were conducted for relevant articles, chapters, and books published before 2016. Search terms used included "bipolar disorder," "cognitive dysfunction," and "dementia." At the end of the selection process, 159 studies were included in our qualitative synthesis. As result, cognitive impairments in BD have been previously considered as infrequent and limited to the affective episodes. Nowadays, there is evidence of stable and lasting cognitive dysfunctions in all phases of BD, including remission phase, particularly in the following domains: attention, memory, and executive functions. The cause of cognitive impairment in BD raises the question if it subtends a neurodevelopmental or a neurodegenerative process. Impaired cognitive functioning associated with BD may contribute significantly to functional disability, in addition to the distorted affective component usually emphasized.

Anti-inflammatory, antiapoptotic, and antioxidant activity of fluoxetine

Fluoxetine is a selective serotonin uptake inhibitor that has been widely used to determine the neurotransmission of serotonin in the central nervous system. This substance has emerged as the drug of choice for the treatment of depression due to is safer profile, fewer side effects, and greater tolerability. Studies have found the following important functions of fluoxetine related to the central nervous system: neuroprotection; anti-inflammatory properties similar to standard drugs for the treatment of inflammatory conditions; antioxidant properties, contributing to its therapeutic action and an important intracellular mechanism underlying the protective pharmacological effects seen in clinical practice in the treatment of different stress-related adverse health conditions; and antiapoptotic properties, with greater neuron survival and a reduction in apoptosis mediators as well as oxidative substances, such as superoxide dismutase and hydrogen peroxide. The aim of this study was to perform a review of the literature on the important role of fluoxetine in anti-inflammatory, cell survival, and neuron trophicity mechanisms (antiapoptotic properties) as well as its role regarding enzymes of the antioxidant defense system.

Correlation between Peripheral Levels of Brain-Derived Neurotrophic Factor and Hippocampal Volume in Children and Adolescents with Bipolar Disorder

Pediatric bipolar disorder (PBD) is a serious mental disorder that affects the development and emotional growth of affected patients. The brain derived neurotrophic factor (BDNF) is recognized as one of the possible markers of the framework and its evolution. Abnormalities in BDNF signaling in the hippocampus could explain the cognitive decline seen in patients with TB. Our aim with this study was to evaluate possible changes in hippocampal volume in children and adolescents with BD and associate them to serum BDNF. Subjects included 30 patients aged seven to seventeen years from the ProCAB (Program for Children and Adolescents with Bipolar Disorder). We observed mean right and left hippocampal volumes of 41910.55 and 41747.96 mm(3), respectively. No statistically significant correlations between peripheral BDNF levels and hippocampal volumes were found. We believe that the lack of correlation observed in this study is due to the short time of evolution of BD in children and adolescents. Besides studies with larger sample sizes to confirm the present findings and longitudinal assessments, addressing brain development versus a control group and including drug-naive patients in different mood states may help clarify the role of BDNF in the brain changes consequent upon BD.

Bcl-2 associated with severity of manic symptoms in bipolar patients in a manic phase

B cell lymphoma protein-2 (Bcl-2) may contribute to the pathophysiology of bipolar disorder, and may be involved in the therapeutic action of anti-manic drugs. The aim of this study was to investigate serum levels of Bcl-2 in bipolar patients in a manic phase, and evaluate the Bcl-2 changes after treatment. We consecutively enrolled 23 bipolar inpatients in a manic phase and 40 healthy subjects; 20 bipolar patients were followed up with treatment. Serum Bcl-2 levels were measured with assay kits. All 20 patients were evaluated by examining the correlation between Bcl-2 levels and Young Mania Rating Scale (YMRS) scores, using Spearman׳s correlation coefficients. The serum Bcl-2 levels in bipolar patients in a manic phase were higher than in healthy subjects, but without a significant difference. The YMRS scores were significantly negatively associated with serum Bcl-2 levels (p=0.042). Bcl-2 levels of the 20 bipolar patients were measured at the end of treatment. Using the Wilcoxon Signed Rank test, we found no significant difference in the Bcl-2 levels of bipolar patients after treatment. Our results suggest that Bcl-2 levels might be an indicator of severity of manic symptoms in bipolar patients in a manic phase.

Genetics of psychotropic medication induced side effects in two independent samples of bipolar patients

The treatment of bipolar disorder (BD) usually requires combination therapies, with the critical issue of the emergence of adverse drug reactions (ADRs) and the possibility of low treatment adherence. Genetic polymorphisms are hypothesized to modulate the pharmacodynamics of psychotropic drugs, representing potential biological markers of ADRs. This study investigated genes involved in the regulation of neuroplasticity (BDNF, ST8SIA2), second messenger cascades (GSK3B, MAPK1, and CREB1), circadian rhythms (RORA), transcription (SP4, ZNF804A), and monoaminergic system (HTR2A and COMT) in the risk of neurological, psychic, autonomic, and other ADRs. Two independent samples of BD patients naturalistically treated were included (COPE-BD n = 147; STEP-BD n = 659). In the COPE-BD 34 SNPs were genotyped, while in the STEP-BD polymorphisms in the selected genes were extracted from the genome-wide dataset. Each ADRs group was categorized as absent-mild or moderate-severe and logistic regression with appropriate covariates was applied to identify possible risk genotypes/alleles. 58.5 and 93.5 % of patients were treated with mood stabilizers, 44.2 and 50.7 % were treated with antipsychotics, and 69.4 and 46.1 % were treated with antidepressants in the COPE-BD and STEP-BD, respectively. Our findings suggested that ST8SIA2 may be associated with psychic ADRs, as shown in the COPE-BD (rs4777989 p = 0.0017) and STEP-BD (rs56027313, rs13379489 and rs10852173). A cluster of RORA SNPs around rs2083074 showed an effect on psychic ADRs in the STEP-BD. Trends supporting the association between HTR2A and autonomic ADRs were found in both samples. Confirmations are needed particularly for ST8SIA2 and RORA since the few available data regarding their role in relation to psychotropic ADRs.

Role of lithium augmentation in the management of major depressive disorder

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

Vascular endothelial growth factor and brain-derived neurotrophic factor in quetiapine treated first-episode psychosis

Objective. It has been suggested that atypical antipsychotics confer their effects via brain-derived neurotrophic factor (BDNF). We investigated the effect of quetiapine on serum levels of BDNF and vascular endothelial growth factor (VEGF) in drug-naive first-episode psychosis subjects. Methods. Fifteen patients drawn from a larger study received quetiapine treatment for twelve weeks. Baseline levels of serum BDNF and VEGF were compared to age- and sex-matched healthy controls and to levels following treatment. Linear regression analyses were performed to determine the relationship of BDNF and VEGF levels with outcome measures at baseline and week 12. Results. The mean serum BDNF level was significantly higher at week 12 compared to baseline and correlated with reductions in Brief Psychiatric Rating Scale (BPRS) and general psychopathology scores. Changes in serum VEGF levels also correlated significantly with a reduction in BPRS scores, a significant improvement in PANNS positive symptoms scores, and displayed a positive relationship with changes in BDNF levels. Conclusions. Our findings suggest that BDNF and VEGF are potential biomarkers for gauging improvement of psychotic symptoms. This suggests a novel neurotrophic-based mechanism of the drug effects of quetiapine on psychosis. This is the first report of VEGF perturbation in psychosis.

Alteration of cyclic-AMP response element binding protein in the postmortem brain of subjects with bipolar disorder and schizophrenia

BACKGROUND

Abnormalities of cyclic-AMP (cAMP) response element binding protein (CREB) function has been suggested in bipolar (BP) illness and schizophrenia (SZ), based on both indirect and direct evidence. To further elucidate the role of CREB in these disorders, we studied CREB expression and function in two brain areas implicated in these disorders, i.e., dorsolateral prefrontal cortex (DLPFC) and cingulate gyrus (CG).

METHODS

We determined CREB protein expression using Western blot technique, CRE-DNA binding using gel shift assay, and mRNA expression using real-time RT-polymerase chain reaction (qPCR) in DLPFC and CG of the postmortem brain of BP (n=19), SZ (n=20), and normal control (NC, n=20) subjects.

RESULTS

We observed that CREB protein and mRNA expression and CRE-DNA binding activity were significantly decreased in the nuclear fraction of DLPFC and CG obtained from BP subjects compared with NC subjects. However, the protein and mRNA expression and CRE-DNA binding in SZ subjects was significantly decreased in CG, but not in DLPFC, compared with NC.

CONCLUSION

These studies thus indicate region-specific abnormalities of CREB expression and function in both BP and SZ. They suggest that abnormalities of CREB in CG may be associated with both BP and SZ, but its abnormality in DLPFC is specific to BP illness.

Lithium's role in neural plasticity and its implications for mood disorders

OBJECTIVE

Lithium (Li) is often an effective treatment for mood disorders, especially bipolar disorder (BPD), and can mitigate the effects of stress on the brain by modulating several pathways to facilitate neural plasticity. This review seeks to summarize what is known about the molecular mechanisms underlying Li's actions in the brain in response to stress, particularly how Li is able to facilitate plasticity through regulation of the glutamate system and cytoskeletal components.

METHOD

The authors conducted an extensive search of the published literature using several search terms, including Li, plasticity, and stress. Relevant articles were retrieved, and their bibliographies consulted to expand the number of articles reviewed. The most relevant articles from both the clinical and preclinical literature were examined in detail.

RESULTS

Chronic stress results in morphological and functional remodeling in specific brain regions where structural differences have been associated with mood disorders, such as BPD. Li has been shown to block stress-induced changes and facilitate neural plasticity. The onset of mood disorders may reflect an inability of the brain to properly respond after stress, where changes in certain regions may become 'locked in' when plasticity is lost. Li can enhance plasticity through several molecular mechanisms, which have been characterized in animal models. Further, the expanding number of clinical imaging studies has provided evidence that these mechanisms may be at work in the human brain.

CONCLUSION

This work supports the hypothesis that Li is able to improve clinical symptoms by facilitating neural plasticity and thereby helps to 'unlock' the brain from its maladaptive state in patients with mood disorders.

Four weeks lithium treatment alters neuronal dendrites in the rat hippocampus

A large body of evidence from molecular, cellular and human studies suggests that lithium may enhance synaptic plasticity, which may be associated with its therapeutic efficacy. However, only a small number of studies have directly assessed this. To determine whether lithium treatment alters structural synaptic plasticity, this study examined the effect of 4 wk lithium treatment on the amount and distribution of dendrites in the dentate gyrus (DG) and hippocampal area CA1 of young adult rats. Following 4 wk lithium or control chow feeding, animals were decapitated, the hippocampi were prepared and stained using a rapid Golgi staining technique and the amount and distribution of the dendritic branching was evaluated using Sholl analyses (method of concentric circles). In the DG, lithium treatment increased the amount and distribution of dendritic branches in the proximal half of dendritic trees of the granule cells and reduced branching in the distal half. In area CA1, the same treatment also increased the number of dendritic branches in the proximal half of apical dendritic trees of CA1 pyramidal cells and reduced branching in the distal half of apical dendritic trees but had no effect on basilar dendritic trees. The lithium treatment altered the total density of dendritic trees in neither the DG nor area CA1. These findings suggest that, in the DG and apical CA1, chronic lithium treatment rearranges neuronal morphology to increase dendritic branching and distribution to where major afferent input is received.

Evaluation of the role of MAPK1 and CREB1 polymorphisms on treatment resistance, response and remission in mood disorder patients

Treatment resistant depression (TRD) is a significant clinical and public health problem. Among others, neuroplasticity and inflammatory pathways seem to play a crucial role in the pathomechanisms of antidepressant efficacy. The primary aim of this study was to investigate whether a set of single nucleotide polymorphisms (SNPs) within two genes implicated in neuroplasticity and inflammatory processes (the mitogen activated protein kinase 1, MAPK1 (rs3810608, rs6928, rs13515 and rs8136867), and the cyclic AMP responsive element binding protein 1, CREB1 (rs889895, rs6740584, rs2551922 and rs2254137)) was associated with antidepressant treatment resistance (according to two different definitions), in 285 Major Depressive Disorder (MDD) patients. As secondary aims, we investigated the genetic modulation of the same SNPs on response, remission and other clinical features both in MDD patients and in a larger sample including 82 Bipolar Disorder (BD) patients as well. All patients were screened in the context of a European multicenter project. No association between both the investigated genes and treatment resistance and response was found in MDD patients. However, considering remission, higher rates of CREB1 rs889895 GG genotype were reported in MDD patients. Moreover, MAPK1 rs8136867 AG genotype was found to be associated with remission in the whole sample (MDD and BD). Present results suggest that some genetic polymorphisms in both CREB1 and MAPK1 could be associated with treatment remission. Although further research is needed to draw more definitive conclusions, such results are intriguing since suggest a potential role of two genes implicated in neuroplasticity and inflammatory processes in symptom remission after antidepressant treatment.

Effects of antipsychotic drugs on the expression of synaptic proteins and dendritic outgrowth in hippocampal neuronal cultures

Recent evidence has suggested that atypical antipsychotic drugs regulate synaptic plasticity. We investigated whether some atypical antipsychotic drugs (olanzapine, aripiprazole, quetiapine, and ziprasidone) altered the expression of synapse-associated proteins in rat hippocampal neuronal cultures under toxic conditions induced by B27 deprivation. A typical antipsychotic, haloperidol, was used for comparison. We measured changes in the expression of various synaptic proteins including postsynaptic density protein-95 (PSD-95), brain-derived neurotrophic factor (BDNF), and synaptophysin (SYP). Then we examined whether these drugs affected the dendritic morphology of hippocampal neurons. We found that olanzapine, aripiprazole, and quetiapine, but not haloperidol, significantly hindered the B27 deprivation-induced decrease in the levels of these synaptic proteins. Ziprasidone did not affect PSD-95 or BDNF levels, but significantly increased the levels of SYP under B27 deprivation conditions. Moreover, olanzapine and aripiprazole individually significantly increased the levels of PSD-95 and BDNF, respectively, even under normal conditions, whereas haloperidol decreased the levels of PSD-95. These drugs increased the total outgrowth of hippocampal dendrites via PI3K signaling, whereas haloperidol had no effect in this regard. Together, these results suggest that the up-regulation of synaptic proteins and dendritic outgrowth may represent key effects of some atypical antipsychotic drugs but that haloperidol may be associated with distinct actions.

Bcl-2 rs956572 polymorphism is associated with increased anterior cingulate cortical glutamate in euthymic bipolar I disorder

B-cell lymphoma 2 (Bcl-2) is an important regulator of cellular plasticity and resilience. In bipolar disorder (BD), studies have shown a key role for a Bcl-2 gene single-nucleotide polymorphism (SNP) rs956572 in the regulation of intracellular calcium (Ca(2+)) dynamics, Bcl-2 expression/levels, and vulnerability to cellular apoptosis. At the same time, Bcl-2 decreases glutamate (Glu) toxicity in neural cells. Abnormalities in Glu function have been implicated in BD. In magnetic resonance spectroscopy (MRS) studies, anterior cingulated cortex (ACC) Glu levels have been reported to be increased in bipolar depression and mania, but no study specifically evaluated ACC Glu levels in BD-euthymia. Here, we compared ACC Glu levels in BD-euthymia compared with healthy subjects using (1)H-MRS and also evaluated the selective role of the rs956572 Bcl-2 SNP in modulating ACC Glu and Glx (sum of Glu and glutamine) in euthymic-BD. Forty euthymic subjects with BD type I and forty healthy controls aged 18-40 were evaluated. All participants were genotyped for Bcl-2 rs956572 and underwent a 3-Tesla brain magnetic resonance imaging examination including the acquisition of an in vivo PRESS single voxel (2 cm(3)) (1)H-MRS sequence to obtain metabolite levels from the ACC. Euthymic-BD subjects had higher Glu/Cre (creatine) and Glx/Cre compared with healthy controls. The Bcl-2 SNP AA genotype was associated with elevated ACC Glu/Cre and Glx/Cre ratio in the BD group but not in controls. The present study reports for the first time an increase in ACC Glu/Cre and Glx/Cre ratios in BD-euthymia. Also, Bcl-2 AA genotype, previously associated with lower Bcl-2 expression and increase intracellular Ca(2+), showed to be associated with increased ACC Glu and Glx levels in euthymic-BD subjects. The present findings reinforce a key role for glutamatergic system dysfunction in the pathophysiology of BD, potentially involving modulatory effects by Bcl-2 in the ACC.

Pharmacological approaches in bipolar disorders and the impact on cognition: a critical overview

OBJECTIVE

Historically, pharmacological treatments for bipolar disorders (BD) have been associated with neurocognitive side-effects. We reviewed studies which assessed the impact of several psychopharmacological drugs on the neurocognitive function of BD patients.

METHOD

The PubMed database was searched for studies published between January 1980 and February 2011, using the following terms: bipolar, bipolar disorder, mania, manic episode, or bipolar depression, cross-referenced with cognitive, neurocognitive, or neuropsychological, cross-referenced with treatment.

RESULTS

Despite methodological flaws in the older studies and insufficient research concerning the newer agents, some consistent findings emerged from the review; lithium appears to have definite, yet subtle, negative effects on psychomotor speed and verbal memory. Among the newer anticonvulsants, lamotrigine appears to have a better cognitive profile than carbamazepine, valproate, topiramate, and zonisamide. More long-term studies are needed to better understand the impact of atypical antipsychotics on BD patients' neurocognitive functioning, both in monotherapy and in association with other drugs. Other agents, like antidepressants and cognitive enhancers, have not been adequately studied in BD so far.

CONCLUSION

Pharmacotherapies for BD should be chosen to minimize neurocognitive side-effects, which may already be compromised by the disease process itself. Neurocognitive evaluation should be considered in BD patients to better evaluate treatment impact on neurocognition. A comprehensive neuropsychological evaluation also addressing potential variables and key aspects such as more severe cognitive deficits, comorbidities, differential diagnosis, and evaluation of multiple cognitive domains in longitudinal follow-up studies are warranted.

The administration of olanzapine and fluoxetine has synergistic effects on intracellular survival pathways in the rat brain

Recently, several studies have emerged suggesting a role of the intracellular survival pathways in the treatment of mood disorders. In addition, the beneficial effects of using a combination of antipsychotics and antidepressants have been shown. With this in mind, we evaluated the effects of the acute administration of fluoxetine (FLX), olanzapine (OLZ) and the combination of fluoxetine/olanzapine on the brain-derived-neurotrophic factor (BDNF), cAMP response element-binding (CREB), Protein Kinase B (PKB, Akt), B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated death promoter (BAD) in the rat brain. Adult Wistar rats received an acute injection of OLZ (3 or 6 mg/kg) and/or FLX (12.5 or 25 mg/kg), and were evaluated for Akt, BDNF, CREB, Bcl-2 and BAD protein levels in the prefrontal cortex, hippocampus and striatum. Our results showed that treatment with FLX and OLZ alone or in combination increased the Akt, CREB, BDNF, Bcl-2 and BAD levels in the prefrontal cortex, hippocampus and striatum. However, the combination of FLX and OLZ at high doses was associated with a greater increase in the levels of Akt in the prefrontal cortex, and did not have an effect on the levels of BAD in any of the brain areas that we evaluated. Finally, these findings further support the hypothesis that treatment with FLX and OLZ alone or in combination exert neuroprotective effects, and that intracellular survival pathways could be involved in the therapeutic effects of combining antipsychotic and antidepressant drugs in mood disorders.

Effects of 4-weeks of treatment with lithium and olanzapine on long-term potentiation in hippocampal area CA1

Neuroplastic theories propose that lithium has robust neuroprotective and neurotrophic actions leading to the up-regulation of synaptic plasticity, and this action may be associated with the efficacy of lithium in the treatment of bipolar disorder. Olanzapine, an atypical antipsychotic drug, is efficacious in the treatment of bipolar disorder. It has been suggested that olanzapine may also up-regulate synaptic plasticity by its neuroprotective and neurotrophic actions, and this action may be related to antipsychotic and anti-manic effects of the drug. However, few studies have directly examined whether these drugs alter synaptic plasticity. In the present study, to examine the effects of lithium and olanzapine on synaptic plasticity, we examined the effects of chronic treatment with lithium and olanzapine on long-term potentiation (LTP) and input and output (I/O) responses of field excitatory postsynaptic potentials (fEPSP) of CA1 pyramidal cells in hippocampal slices prepared from rats administered the drugs for 4 weeks. Our results show that 4 weeks of lithium treatment magnified LTP of CA1 pyramidal cells. However, the same treatment with olanzapine did not magnify LTP of CA1 pyramidal cells. Four weeks of treatment with lithium did not alter I/O responses of CA1 pyramidal cells. However, the same treatment with olanzapine increased I/O responses of CA1 pyramidal cells. The results suggest that lithium up-regulates synaptic plasticity in the hippocampus, and olanzapine increases synaptic transmission without apparent changes in LTP in the hippocampus.

Bipolarity and inadequate response to antidepressant drugs: clinical and psychopharmacological perspective

OBJECTIVES

The reason why depression may respond poorly to treatment with antidepressant drugs may be connected with the features of bipolarity. Evidence to this effect has accumulated in recent studies of various kinds of depression in mood disorders. Additional evidence for such a connection may be the efficacy of mood-stabilizing drugs in the augmentation of antidepressants in treatment-resistant depression.

METHODS

This review is based on clinical and psychopharmacological research performed over the past five years. The clinical investigation was based on the response to antidepressants of bipolar depression or to symptoms of hypomania, assessed mainly by the Mood Disorder Questionnaire (MDQ) and the Hypomania Checklist-32 (HCL-32). The psychopharmacological research tested the efficacy of augmentation of antidepressants in treatment-resistant depression by mood-stabilizing drugs of the 1st and 2nd generations.

RESULTS

A number of studies have pointed to an association between bipolar depression, or symptoms of hypomania and an inadequate response to antidepressants. Such a connection was also found in the Polish TRES-DEP study which included 1051 depressed patients. Pharmacological studies have demonstrated the efficacy of first generation mood-stabilizing drugs (lithium, carbamazepine) and second generation drugs (quetiapine, olanzapine, risperidone, ziprasidone, lamotrigine) for augmentation of antidepressants in treatment-resistant depression. Some evidence has been presented that mixed depressive episodes may also belong to this category.

CONCLUSIONS

The results of these clinical and psychopharmacological studies appear to confirm an association between bipolarity and a poor response of depression to treatment with antidepressant drugs.

Antipsychotics in the treatment of bipolar disorder

Atypical antipsychotics have an important role in the acute and maintenance treatment of bipolar disorder. While robust evidence supports the efficacy of these agents in the treatment of mania and in the prevention of manic relapse, few atypical antipsychotics have shown efficacy in the treatment or prevention of depressive episodes. These agents pose a lower risk of extrapyramidal side effects compared to typical neuroleptics, but carry a significant liability for weight gain and other metabolic side effects such as hyperglycemia and hyperlipidemia. More comparative effectiveness studies are needed to assess the optimal treatment regimens, including the relative benefits and risks of antipsychotics versus mood stabilizers. The exploration of the molecular mechanisms of antipsychotics has helped to shed further light on the underlying neurobiology of bipolar disorder, since these compounds target systems thought to be key to the pathophysiology of bipolar disorder. In addition to modulating monoaminergic neurotransmission, atypical antipsychotics appear to share properties with mood-stabilizing agents known to alter intracellular signal transduction leading to changes in neuronal activity and gene expression. Atypical antipsychotic drugs have been shown to exhibit neuroprotective properties that are mediated by upregulation of trophic and cellular resilience factors. Building on our understanding of existing therapeutics, especially as it relates to underlying disease pathology, newer "plasticity enhancing" strategies hold promise for future treatments of bipolar disorder.

Bcl-2 interaction with the inositol 1,4,5-trisphosphate receptor: role in Ca(2+) signaling and disease

The Bcl-2 protein, best known for its ability to inhibit apoptosis, interacts with the inositol 1,4,5-trisphosphate receptor (IP(3)R) Ca(2+) channel to regulate IP(3)-mediated Ca(2+) release from the endoplasmic reticulum. This review summarizes the current state of knowledge regarding the interaction of Bcl-2, and also its homologue Bcl-xl, with the IP(3)R and how these interactions regulate Ca(2+) signaling. The dual role of these interactions in promoting prosurvival Ca(2+) signals, while at the same time inhibiting proapoptotic Ca(2+) signals, is discussed. Moreover, this review will elucidate the recently recognized importance of the Bcl-2-IP(3)R interaction in human disease.

The Bcl-2 gene polymorphism rs956572AA increases inositol 1,4,5-trisphosphate receptor-mediated endoplasmic reticulum calcium release in subjects with bipolar disorder

BACKGROUND

Bipolar disorder (BPD) is characterized by altered intracellular calcium (Ca(2+)) homeostasis. Underlying mechanisms involve dysfunctions in endoplasmic reticulum (ER) and mitochondrial Ca(2+) handling, potentially mediated by B-cell lymphoma 2 (Bcl-2), a key protein that regulates Ca(2+) signaling by interacting directly with these organelles, and which has been implicated in the pathophysiology of BPD. Here, we examined the effects of the Bcl-2 gene single nucleotide polymorphism (SNP) rs956572 on intracellular Ca(2+) dynamics in patients with BPD.

METHODS

Live cell fluorescence imaging and electron probe microanalysis were used to measure intracellular and intra-organelle free and total calcium in lymphoblasts from 18 subjects with BPD carrying the AA, AG, or GG variants of the rs956572 SNP. Analyses were carried out under basal conditions and in the presence of agents that affect Ca(2+) dynamics.

RESULTS

Compared with GG homozygotes, variant AA-which expresses significantly reduced Bcl-2 messenger RNA and protein-exhibited elevated basal cytosolic Ca(2+) and larger increases in inositol 1,4,5-trisphosphate receptor-mediated cytosolic Ca(2+) elevations, the latter in parallel with enhanced depletion of the ER Ca(2+) pool. The aberrant behavior of AA cells was reversed by chronic lithium treatment and mimicked in variant GG by a Bcl-2 inhibitor. In contrast, no differences between SNP variants were found in ER or mitochondrial total Ca(2+) content or in basal store-operated Ca(2+) entry.

CONCLUSIONS

These results demonstrate that, in patients with BPD, abnormal Bcl-2 gene expression in the AA variant contributes to dysfunctional Ca(2+) homeostasis through a specific ER inositol 1,4,5-trisphosphate receptor-dependent mechanism.

A genetic network model of cellular responses to lithium treatment and cocaine abuse in bipolar disorder

Background

Lithium is an effective treatment for Bipolar Disorder (BD) and significantly reduces suicide risk, though the molecular basis of lithium's effectiveness is not well understood. We seek to improve our understanding of this effectiveness by posing hypotheses based on new experimental data as well as published data, testing these hypotheses in silico, and posing new hypotheses for validation in future studies. We initially hypothesized a gene-by-environment interaction where lithium, acting as an environmental influence, impacts signal transduction pathways leading to differential expression of genes important in the etiology of BD mania.

Results

Using microarray and rt-QPCR assays, we identified candidate genes that are differentially expressed with lithium treatment. We used a systems biology approach to identify interactions among these candidate genes and develop a network of genes that interact with the differentially expressed candidates. Notably, we also identified cocaine as having a potential influence on the network, consistent with the observed high rate of comorbidity for BD and cocaine abuse. The resulting network represents a novel hypothesis on how multiple genetic influences on bipolar disorder are impacted by both lithium treatment and cocaine use. Testing this network for association with BD and related phenotypes, we find that it is significantly over-represented for genes that participate in signal transduction, consistent with our hypothesized-gene-by environment interaction. In addition, it models related pharmacogenomic, psychiatric, and chemical dependence phenotypes.

Conclusions

We offer a network model of gene-by-environment interaction associated with lithium's effectiveness in treating BD mania, as well as the observed high rate of comorbidity of BD and cocaine abuse. We identified drug targets within this network that represent immediate candidates for therapeutic drug testing. Posing novel hypotheses for validation in future work, we prioritized SNPs near genes in the network based on functional annotation. We also developed a "concept signature" for the genes in the network and identified additional candidate genes that may influence the system because they are significantly associated with the signature.

Effects of olanzapine on brain-derived neurotrophic factor gene promoter activity in SH-SY5Y neuroblastoma cells

PURPOSE

Atypical antipsychotics have neuroprotective effects, which may be one of the mechanisms for their success in the treatment of schizophrenia. Growing evidence suggest that brain-derived neurotrophic factor (BDNF) is abnormally regulated in patients with schizophrenia, and its expression can be up-regulated by atypical antipsychotics. Atypical antipsychotic drugs may positively regulate transcription of the BDNF gene, but the molecular mechanism of atypical antipsychotic drug action on BDNF gene activity has not been investigated. The aim of the present study was to explore the possible involvement of some intracellular signaling pathways in olanzapine action on BDNF promoter activity.

METHODS

We examined the effects of olanzapine on BDNF gene promoter activity in SH-SY5Y cells transfected with a rat BDNF promoter fragment (-108 to +340) linked to the luciferase reporter gene. The changes in glycogen synthase kinase-3beta (GSK-3beta) and cAMP response element (CRE) binding protein (CREB) phosphorylation were measured by Western blot analysis.

RESULTS

Olanzapine treatment (10-100 microM) increased basal BDNF gene promoter activity in a dose-dependent manner and increased protein levels at high dose, and inhibitors of protein kinase A (PKA), H-89 (10 microM), phosphatidylinositol 3-kinase (PI3K), wortmannin (0.01 microM), PKC (protein kinase C), GF109203 (10 microM), calcium/calmodulin kinase II (CaMKII), and KN-93 (20 microM) partially attenuated the stimulatory effect of olanzapine on BDNF promoter activity. In line with these results, a Western blot study showed that olanzapine (100 microM) increased phosphorylated levels of GSK-3beta and CREB, which are notable downstream effectors of the PKA, PI3K, PKC, and CaMKII signaling pathways.

CONCLUSIONS

These results demonstrate that the up-regulation of olanzapine on BDNF gene transcription is linked with enhancement of CREB-mediated transcription via PKA, PI3K, PKC, and CaMKII signaling pathways, and olanzapine may exert neuroprotective effects through these signaling pathways in neuronal cells.

The neuropeptide VGF is reduced in human bipolar postmortem brain and contributes to some of the behavioral and molecular effects of lithium

Recent studies demonstrate that the neuropeptide VGF (nonacronymic) is regulated in the hippocampus by antidepressant therapies and animal models of depression and that acute VGF treatment has antidepressant-like activity in animal paradigms. However, the role of VGF in human psychiatric disorders is unknown. We now demonstrate using in situ hybridization that VGF is downregulated in bipolar disorder in the CA region of the hippocampus and Brodmann's area 9 of the prefrontal cortex. The mechanism of VGF in relation to LiCl was explored. Both LiCl intraperitoneally and VGF intracerebroventricularly reduced latency to drink in novelty-induced hypophagia, and LiCl was not effective in VGF(+/-) mice, suggesting that VGF may contribute to the effects of LiCl in this behavioral procedure that responds to chronic antidepressant treatment. VGF by intrahippocampal injection also had novel activity in an amphetamine-induced hyperlocomotion assay, thus mimicking the actions of LiCl injected intraperitoneally in a system that phenocopies manic-like behavior. Moreover, VGF(+/-) mice exhibited increased locomotion after amphetamine treatment and did not respond to LiCl, suggesting that VGF is required for the effects of LiCl in curbing the response to amphetamine. Finally, VGF delivered intracerebroventricularly in vivo activated the same signaling pathways as LiCl and is necessary for the induction of mitogen-activated protein kinase and Akt by LiCl, thus lending insight into the molecular mechanisms underlying the actions of VGF. The dysregulation of VGF in bipolar disorder as well as the behavioral effects of the neuropeptide similar to LiCl suggests that VGF may underlie the pathophysiology of bipolar disorder.

Increase in brain-derived neurotrophic factor in first episode psychotic patients after treatment with atypical antipsychotics

Some preclinical and postmortem studies suggest that the effects of atypical antipsychotics could be mediated by brain-derived neurotrophic factor (BDNF). Olanzapine is an atypical antipsychotic with shown efficacy in psychosis treatment. The aim of this study was to compare plasma BDNF levels at baseline and after 1 year of olanzapine treatment in 18 drug-naive patients who experienced a first psychotic episode with those of 18 healthy control participants matched by age, sex, and socioeconomic level. Plasma BDNF levels were measured in patients at the index episode and at 1, 6, and 12 months of follow-up using an enzyme-linked immunosorbent assay. Symptoms and functioning of patients and controls were assessed with the Positive and Negative Symptom Scale and Global Assessment of Function Scale. BDNF levels of patients at onset were significantly lower than controls but increased toward control values during olanzapine treatment. There was a significant positive correlation between BDNF levels and functioning (Global Assessment of Function Scale). BDNF levels were also negatively correlated with positive symptoms, but not with negative symptoms or general psychopathology. Results suggest that olanzapine can offset the low BDNF levels at the onset of first psychotic episodes, and improving psychotic symptoms. The increase in BDNF levels may be its mechanism of action in improving positive symptoms.

An inverse relationship between cortisol and BDNF levels in schizophrenia: data from human postmortem and animal studies

Stress and stress-induced glucocorticoids have been implicated in many neuropsychiatric disorders including schizophrenia. In addition, the neurotrophin, brain derived neurotrophic factor (BDNF) has been shown to play an important role in stress-mediated changes in neuroplasticity, however, the exact relationship between glucocorticoid and BDNF levels in schizophrenia is unclear. Here, we measured the levels of cortisol (a major glucocorticoid hormone in humans) and BDNF in prefrontal cortex and CSF samples of postmortem schizophrenia subjects. We also assessed the levels of cortisol and BDNF in the frontal cortex and plasma from an animal model (the offspring of prenatally stressed rats), which demonstrates several behavioral and neuroendocrine abnormalities similar to schizophrenia. A significant increase in cortisol levels was found in prefrontal cortex and CSF samples from subjects with schizophrenia. The BDNF levels were significantly lower in prefrontal cortex and CSF samples of subjects with schizophrenia (compared to age-matched controls). Data from animal studies indicated that prenatally stressed offspring have significantly higher plasma and prefrontal cortex cortisol, whereas BDNF levels were significantly lower when compared to control, non-stressed offspring. Moreover, olanzapine treatment for 45 days starting at postnatal day 60 significantly attenuated prenatal stress-induced increase in cortisol levels in prefrontal cortex, but no change in BDNF levels was observed after olanzapine treatment. A significant negative correlation between BDNF and cortisol was observed in both human and animal studies. The above data from human and animal studies suggest that a negative association between stress hormone, cortisol and neuroprotective molecule, BDNF plays an important role in the pathophysiology of schizophrenia.

Altered expression of apoptotic factors and synaptic markers in postmortem brain from bipolar disorder patients

Bipolar disorder (BD) is a progressive psychiatric disorder characterized by recurrent changes of mood and is associated with cognitive decline. There is evidence of excitotoxicity, neuroinflammation, upregulated arachidonic acid (AA) cascade signaling and brain atrophy in BD patients. These observations suggest that BD pathology may be associated with apoptosis as well as with disturbed synaptic function. To test this hypothesis, we measured mRNA and protein levels of the pro-apoptotic (Bax, BAD, caspase-9 and caspase-3) and anti-apoptotic factors (BDNF and Bcl-2) and of pre- and post-synaptic markers (synaptophysin and drebrin), in postmortem prefrontal cortex (Brodmann area 9) from 10 BD patients and 10 age-matched controls. Consistent with the hypothesis, BD brains showed significant increases in protein and mRNA levels of the pro-apoptotic factors and significant decreases of levels of the anti-apoptotic factors and the synaptic markers, synaptophysin and drebrin. These differences may contribute to brain atrophy and progressive cognitive changes in BD.