Enhancing neuronal plasticity and cellular resilience to develop novel, improved therapeutics for difficult-to-treat depression

Dextromethorphan/quinidine pharmacotherapy in patients with treatment resistant depression: A proof of concept clinical trial

BACKGROUND

At least one-third of patients with major depressive disorder (MDD) have treatment-resistant depression (TRD), defined as lack of response to two or more adequate antidepressant trials. For these patients, novel antidepressant treatments are urgently needed.

METHODS

The current study is a phase IIa open label clinical trial examining the efficacy and tolerability of a combination of dextromethorphan (DM) and the CYP2D6 enzyme inhibitor quinidine (Q) in patients with TRD. Dextromethorphan acts as an antagonist at the glutamate N-methyl-d-aspartate (NMDA) receptor, in addition to other pharmacodynamics properties that include activity at sigma-1 receptors. Twenty patients with unipolar TRD who completed informed consent and met all eligibility criteria we enrolled in an open-label study of DM/Q up to 45/10mg by mouth administered every 12h over the course of a 10-week period, and constitute the intention to treat (ITT) sample. Six patients discontinued prior to study completion.

RESULTS

There was no treatment-emergent suicidal ideation, psychotomimetic or dissociative symptoms. Montgomery-Asberg Depression Rating Scale (MADRS) score was reduced from baseline to the 10-week primary outcome (mean change: -13.0±11.5, t₁₉=5.0, p<0.001), as was QIDS-SR score (mean change: -5.9±6.6, t₁₉=4.0, p<0.001). The response and remission rates in the ITT sample were 45% and 35%, respectively.

LIMITATIONS

Open-label, proof-of-concept design.

CONCLUSIONS

Herein we report acceptable tolerability and preliminary efficacy of DM/Q up to 45/10mg administered every 12h in patients with TRD. Future larger placebo controlled randomized trials in this population are warranted.

Classics in Chemical Neuroscience: Ketamine

Ketamine, a molecule of many faces, has contributed immeasurably to numerous realms of clinical practice and scientific inquiry. From anesthesia and analgesia to depression and schizophrenia, it continues to shed light on the molecular underpinnings of pain, consciousness, and the pathophysiology of neuropsychiatric disorders. In particular, research on ketamine's mechanism of action is providing new hope in the search for therapies for treatment-resistant depression and affords insights into disorders of glutamatergic dysfunction. In this Review, we will cover aspects of ketamine's synthesis, manufacturing, metabolism, pharmacology, approved and off-label indications, and adverse effects. We will also discuss the captivating history of this molecule, its influence on neuropsychiatry, and its potential to advance the fields of chemical neuroscience and neuropharmacology.

Lifestyle Modulators of Neuroplasticity: How Physical Activity, Mental Engagement, and Diet Promote Cognitive Health during Aging

The number of the elderly across the globe will approximate 2.1 billion by 2050. Juxtaposed against this burgeoning segment of the population is evidence that nonpathological aging is associated with an increased risk for cognitive decline in a variety of domains, changes that can cause mild disability even before the onset of dementia. Given that pharmacological treatments that mitigate dementia are still outstanding, alternative therapeutic options are being investigated increasingly. The results from translational studies have shown that modifiable lifestyle factors-including physical activity, cognitive engagement, and diet-are a key strategy for maintaining brain health during aging. Indeed, a multiplicity of studies has demonstrated relationships between lifestyle factors, brain structure and function, and cognitive function in aging adults. For example, physical activity and diet modulate common neuroplasticity substrates (neurotrophic signaling, neurogenesis, inflammation, stress response, and antioxidant defense) in the brain whereas cognitive engagement enhances brain and cognitive reserve. The aims of this review are to evaluate the relationship between modifiable lifestyle factors, neuroplasticity, and optimal brain health during aging; to identify putative mechanisms that contribute positive brain aging; and to highlight future directions for scientists and clinicians. Undoubtedly, the translation of cutting-edge knowledge derived from the field of cognitive neuroscience will advance our understanding and enhance clinical treatment interventions as we endeavor to promote brain health during aging.

GABAergic neurons in nucleus accumbens are correlated to resilience and vulnerability to chronic stress for major depression

BACKGROUND

Major depression, persistent low mood, is one of common psychiatric diseases. Chronic stressful life is believed to be a major risk factor that leads to dysfunctions of the limbic system. However, a large number of the individuals with experiencing chronic stress do not suffer from major depression, called as resilience. Endogenous mechanisms underlying neuronal invulnerability to chronic stress versus major depression are largely unknown. As GABAergic neurons are vulnerable to chronic stress and their impairments is associated with major depression, we have examined whether the invulnerability of GABAergic neurons in the limbic system is involved in resilience.

RESULTS

GABAergic neurons in the nucleus accumbens from depression-like mice induced by chronic unpredictable mild stress appear the decreases in their GABA release, spiking capability and excitatory input reception, compared with those in resilience mice. The levels of decarboxylase and vesicular GABA transporters decrease in depression-like mice, but not resilience.

MATERIALS AND METHODS

Mice were treated by chronic unpredictable mild stress for three weeks. Depression-like behaviors or resilience was confirmed by seeing whether their behaviors change significantly in sucrose preference, Y-maze and forced swimming tests. Mice from controls as well as depression and resilience in response to chronic unpredictable mild stress were studied in terms of GABAergic neuron activity in the nucleus accumbens by cell electrophysiology and protein chemistry.

CONCLUSIONS

The impairment of GABAergic neurons in the nucleus accumbens is associated with major depression. The invulnerability of GABAergic neurons to chronic stress may be one of cellular mechanisms for the resilience to chronic stress.

Physical Activity Modulates Common Neuroplasticity Substrates in Major Depressive and Bipolar Disorder

Mood disorders (MDs) are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility, a need remains to better understand the interrelated mechanisms that contribute to neuroplasticity deficits in MDs and the means by which various therapeutics mitigate them. Of those therapeutics being investigated, physical activity (PA) has shown clear and consistent promise. Accordingly, the aims of this review are to (1) explicate key modulators, processes, and interactions that impinge upon multiple susceptibility points to effectuate neuroplasticity deficits in MDs; (2) explore the putative mechanisms by which PA mitigates these features; (3) review protocols used to induce the positive effects of PA in MDs; and (4) highlight implications for clinicians and researchers.

Effects of ketamine administration on mTOR and reticulum stress signaling pathways in the brain after the infusion of rapamycin into prefrontal cortex

Recent studies show that activation of the mTOR signaling pathway is required for the rapid antidepressant actions of glutamate N-methyl-D-aspartate (NMDA) receptor antagonists. A relationship between mTOR kinase and the endoplasmic reticulum (ER) stress pathway, also known as the unfolded protein response (UPR) has been shown. We evaluate the effects of ketamine administration on the mTOR signaling pathway and proteins of UPR in the prefrontal cortex (PFC), hippocampus, amygdala and nucleus accumbens, after the inhibiton of mTOR signaling in the PFC. Male adult Wistar rats received pharmacological mTOR inhibitor, rapamycin (0.2 nmol), or vehicle into the PFC and then a single dose of ketamine (15 mg/kg, i.p.). The immunocontent of mTOR, eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), eukaryotic elongation factor 2 kinase (eEF2K) homologous protein (CHOP), PKR-like ER kinase (PERK) and inositol-requiring enzyme 1 (IRE1) - alpha were determined in the brain. The mTOR levels were reduced in the rapamycin group treated with saline and ketamine in the PFC; p4EBP1 levels were reduced in the rapamycin group treated with ketamine in the PFC and nucleus accumbens; the levels of peEF2K were increased in the PFC in the vehicle group treated with ketamine and reduced in the rapamycin group treated with ketamine. The PERK and IRE1-alpha levels were decreased in the PFC in the rapamycin group treated with ketamine. Our results suggest that mTOR signaling inhibition by rapamycin could be involved, at least in part, with the mechanism of action of ketamine; and the ketamine antidepressant on ER stress pathway could be also mediated by mTOR signaling pathway in certain brain structures.

Targeting glutamate signalling in depression: progress and prospects

Major depressive disorder (MDD) is severely disabling, and current treatments have limited efficacy. The glutamate N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine was recently repurposed as a rapidly acting antidepressant, catalysing the vigorous investigation of glutamate-signalling modulators as novel therapeutic agents for depressive disorders. In this Review, we discuss the progress made in the development of such modulators for the treatment of depression, and examine recent preclinical and translational studies that have investigated the mechanisms of action of glutamate-targeting antidepressants. Fundamental questions remain regarding the future prospects of this line of drug development, including questions concerning safety and tolerability, efficacy, dose-response relationships and therapeutic mechanisms.

White matter atrophy and myelinated fiber disruption in a rat model of depression

Brain imaging and postmortem studies have indicated that white matter abnormalities may contribute to the pathology and pathogenesis of depression. However, until now, no study has quantitatively investigated white matter changes in depression in rats. The current study used the chronic unpredictable stress (CUS) model of depression. Body weight and sucrose preference test (SPT) scores were assessed weekly. Upon successfully establishing the CUS animal model, all animals were tested using the SPT and the open field test (OFT). Then, transmission electron microscopy and unbiased stereological methods were used to investigate white matter changes in the rats. Compared with the control group, the body weight and sucrose preference of the CUS rats were significantly decreased (p < .001, p < .001, respectively). In the OFT, the total time spent and the total distance traveled in the inner area by the CUS rats were significantly lower than those of the control group (p = .002, p = .001, respectively). The stereological results revealed that white matter volume, the total volume, and the total length and mean diameter of myelinated fibers in the white matter of the CUS rats were significantly decreased compared to the control rats (p = .042, p = .038, p = .035, p = .019, respectively). The results of this study suggested that white matter atrophy and disruption of myelinated fibers in the white matter may contribute to the pathophysiology underlying depression, which might provide new targets for the development of novel therapeutic interventions for depression.

Towards the Molecular Foundations of Glutamatergic-targeted Antidepressants

BACKGROUND

Depression affects over 120 million individuals of all ages and is the leading cause of disability worldwide. The lack of objective diagnostic criteria, together with the heterogeneity of the depressive disorder itself, makes it challenging to develop effective therapies. The accumulation of preclinical data over the past 20 years derived from a multitude of models using many divergent approaches, has fueled the resurgence of interest in targeting glutamatergic neurotransmission for the treatment of major depression.

OBJECTIVE

The emergence of mechanistic studies are advancing our understanding of the molecular underpinnings of depression. While clearly far from complete and conclusive, they offer the potential to lead to the rational design of more specific therapeutic strategies and the development of safer and more effective rapid acting, long lasting antidepressants.

METHODS

The development of comprehensive omics-based approaches to the dysregulation of synaptic transmission and plasticity that underlies the core pathophysiology of MDD are reviewed to illustrate the fundamental elements.

RESULTS

This review frames the rationale for the conceptualization of depression as a "pathway disease". As such, it culminates in the call for the development of novel state-of-the-art "-omics approaches" and neurosystems biological techniques necessary to advance our understanding of spatiotemporal interactions associated with targeting glutamatergic-triggered signaling in the CNS.

CONCLUSION

These technologies will enable the development of novel psychiatric medications specifically targeted to impact specific, critical intracellular networks in a more focused manner and have the potential to offer new dimensions in the area of translational neuropsychiatry.

Low Potential of Basimglurant to Be Involved in Drug-Drug Interactions: Influence of Non-Michaelis-Menten P450 Kinetics on Fraction Metabolized

Basimglurant, a novel mGlu5-negative allosteric modulator under development for the treatment of major depressive disorder, is cleared via cytochrome P450 (P450)-mediated oxidative metabolism. Initial enzyme phenotyping studies indicated that CYP3A4/5 dominates basimglurant metabolism and highlights a risk for drug-drug interactions when it is comedicated with strong CYP3A4/5 inhibitors or inactivators; however, a clinical drug-drug interaction (DDI) study using the potent and selective CYP3A4/5 inhibitor ketoconazole resulted in an area under the curve (AUC) AUCi/AUC ratio of only 1.24. A further study using the CYP3A4 inducer carbamazepine resulted in an AUCi/AUC ratio of 0.69. More detailed in vitro enzyme phenotyping and kinetics studies showed that, at the low concentrations attained clinically, basimglurant metabolic clearance is catalyzed mainly by CYP1A2. The relative contributions of the enzymes were estimated as 70:30 CYP1A2:CYP3A4/5. Using this information, a clinical study using the CYP1A2 inhibitor fluvoxamine was performed, resulting in an AUCi/AUC ratio of 1.60, confirming the role of CYP1A2 and indicating a balanced DDI risk profile. Basimglurant metabolism kinetics show enzyme dependency: CYP1A2-mediated metabolism follows Michaelis-Menten kinetics, whereas CYP3A4 and CYP3A5 follow sigmoidal kinetics [with similar constant (KM) and S50 values]. The interplay of the different enzyme kinetics leads to changing fractional enzyme contributions to metabolism with substrate concentration, even though none of the metabolic enzymes is saturated. This example demonstrates the relevance of non-Michaelis-Menten P450 enzyme kinetics and highlights the need for a thorough understanding of metabolism enzymology to make accurate predictions for human metabolism in vivo.

Influence of BclI C/G (rs41423247) on hippocampal shape and white matter integrity of the parahippocampal cingulum in major depressive disorder

We investigated the interactive effects of BclI C/G (rs41423247) allelic variants and the diagnosis of major depressive disorder (MDD) on hippocampal shape and integrity of the left parahippocampal subdivision of the cingulum. Fifty-two patients with MDD and 52 healthy controls (HCs) underwent T1-weighted structural magnetic resonance imaging and BclI C/G (rs41423247) genotyping. We analyzed hippocampal shape using the FIRST module of FSL and analyzed white matter (WM) integrity using diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS). Significant alterations in left hippocampal shape and decreased fractional anisotropy (FA) values of the left parahippocampal cingulum were observed in MDD patients, compared to HCs. In addition, MDD patients of the BclI minor (G-) allele carrier group showed significant alterations in left hippocampal shape and decreased FA values of the left parahippocampal cingulum compared to BclI minor (G-) allele carrier HCs. No significant differences between diagnostic subgroups of the C/C homozygotes were observed. Our study provides evidence for alterations in hippocampal shape and decreased integrity of the WM region associated with the hippocampus in MDD, and for the possible influence of BclI C/G polymorphism (rs41423247) on hippocampal shape and integrity of the parahippocampal subdivision of the cingulum in depression.

Multi-target therapeutics for neuropsychiatric and neurodegenerative disorders

Historically, neuropsychiatric and neurodegenerative disease treatments focused on the 'magic bullet' concept; however multi-targeted strategies are increasingly attractive gauging from the escalating research in this area. Because these diseases are typically co-morbid, multi-targeted drugs capable of interacting with multiple targets will expand treatment to the co-morbid disease condition. Despite their theoretical efficacy, there are significant impediments to clinical success (e.g., difficulty titrating individual aspects of the drug and inconclusive pathophysiological mechanisms). The new and revised diagnostic frameworks along with studies detailing the endophenotypic characteristics of the diseases promise to provide the foundation for the circumvention of these impediments. This review serves to evaluate the various marketed and nonmarketed multi-targeted drugs with particular emphasis on their design strategy.

Discovery of serum protein biomarkers in drug-free patients with major depressive disorder

OBJECTIVE

Major depressive disorder (MDD) is a systemic and multifactorial disorder involving complex interactions between genetic predisposition and disturbances of various molecular pathways. Its underlying molecular pathophysiology remains unclear, and no valid and objective diagnostic tools for the condition are available.

METHODS

We performed large-scale proteomic profiling to identify novel peripheral biomarkers implicated in the pathophysiology of MDD in 25 drug-free female MDD patients and 25 healthy controls. First, quantitative serum proteome profiles were obtained and analyzed by liquid chromatography-tandem mass spectrometry using serum samples from 10 MDD patients and 10 healthy controls. Next, candidate biomarker sets, including differentially expressed proteins from the profiling experiment and those identified in the literature, were verified using multiple-reaction monitoring in 25 patients and 25 healthy controls. The final panel of potential biomarkers was selected using multiparametric statistical analysis.

RESULTS

We identified a serum biomarker panel consisting of six proteins: apolipoprotein D, apolipoprotein B, vitamin D-binding protein, ceruloplasmin, hornerin, and profilin 1, which could be used to distinguish MDD patients from controls with 68% diagnostic accuracy. Our results suggest that modulation of the immune and inflammatory systems and lipid metabolism are involved in the pathophysiology of MDD.

CONCLUSIONS

Our findings of functional proteomic changes in the peripheral blood of patients with MDD further clarify the molecular biological pathway underlying depression. Further studies using larger, independent cohorts are needed to verify the role of these candidate biomarkers for the diagnosis of MDD.

Duality of Antidepressants and Neuroprotectants

The co-morbidity of neuropsychiatric disorders, particularly major depressive disorder (MDD) with neurodegenerative diseases, in particular Parkinson's disease (PD) is now well recognized. Indeed, it is suggested that depressive disorders, especially in late life, may be an indication of latent neurodegeneration. Thus, it is not unreasonable to expect that deterrents of MDD may also deter the onset and/or progression of the neurodegenerative diseases including PD. In this review, examples of neuroprotective efficacy of established as well as prospective antidepressants are provided. Conversely, mood-regulating effects of some neuroprotective drugs are also presented. Thus, in addition to currently used antidepressants, ketamine, nicotine, curcumin, and resveratrol are discussed for their dual efficacy. In addition, potential neurobiological substrates for their actions are presented. It is concluded that pharmacological developments of mood-regulating or neuroprotective drugs can have cross benefit in co-morbid conditions of neuropsychiatric and neurodegenerative disorders and that inflammatory and neurotrophic factors play important roles in both conditions.

Organ-to-Cell-Scale Health Assessment Using Geographical Information System Approaches with Multibeam Scanning Electron Microscopy

This study combines novel multibeam electron microscopy with a geographical information system approach to create a first, seamless, navigable anatomic map of the human hip and its cellular inhabitants. Using spatial information acquired by localizing relevant map landmarks (e.g. cells, blood vessels), network modeling will enable disease epidemiology studies in populations of cells inhabiting tissues and organs.

Reproductive Steroid Regulation of Mood and Behavior

In this article, we examine evidence supporting the role of reproductive steroids in the regulation of mood and behavior in women and the nature of that role. In the first half of the article, we review evidence for the following: (i) the reproductive system is designed to regulate behavior; (ii) from the subcellular to cellular to circuit to behavior, reproductive steroids are powerful neuroregulators; (iii) affective disorders are disorders of behavioral state; and (iv) reproductive steroids affect virtually every system implicated in the pathophysiology of depression. In the second half of the article, we discuss the diagnosis of the three reproductive endocrine-related mood disorders (premenstrual dysphoric disorder, postpartum depression, and perimenopausal depression) and present evidence supporting the relevance of reproductive steroids to these conditions. Existing evidence suggests that changes in reproductive steroid levels during specific reproductive states (i.e., the premenstrual phase of the menstrual cycle, pregnancy, parturition, and the menopause transition) trigger affective dysregulation in susceptible women, thus suggesting the etiopathogenic relevance of these hormonal changes in reproductive mood disorders. Understanding the source of individual susceptibility is critical to both preventing the onset of illness and developing novel, individualized treatments for reproductive-related affective dysregulation. © 2016 American Physiological Society. Compr Physiol 6:1135-1160, 2016e.

Serum cortisol and BDNF in patients with major depression-effect of yoga

Depression is associated with low serum Brain Derived Neurotrophic Factor (BDNF) and elevated levels of serum cortisol. Yoga practices have been associated with antidepressant effects, increase in serum BDNF, and reduction in serum cortisol. This study examined the association between serum BDNF and cortisol levels in drug-naïve patients with depression treated with antidepressants, yoga therapy, and both. Fifty-four drug-naïve consenting adult outpatients with Major Depression (32 males) received antidepressants only (n = 16), yoga therapy only (n = 19), or yoga with antidepressants (n = 19). Serum BDNF andcortisol levels were obtained before and after 3 months using a sandwich ELISA method. One-way ANOVA, Chi-square test, and Pearson's correlation tests were used for analysis. The groups were comparable at baseline on most parameters. Significant improvement in depression scores and serum BDNF levels, and reduction in serum cortisol in the yoga groups, have been described in previous reports. A significant negative correlation was observed between change in BDNF (pre-post) and cortisol (pre-post) levels in the yoga-only group (r = -0.59, p = 0.008). In conclusion, yoga may facilitate neuroplasticity through stress reduction in depressed patients. Further studies are needed to confirm the findings and delineate the pathways for these effects.

A double-tracer technique to characterize absorption, distribution, metabolism and excretion (ADME) of [14C]-basimglurant and absolute bioavailability after oral administration and concomitant intravenous microdose administration of [13C6]-labeled basimglurant in humans

1. The emerging technique of employing intravenous microdose administration of an isotope tracer concomitantly with an [¹⁴C]-labeled oral dose was used to characterize the disposition and absolute bioavailability of a novel metabotropic glutamate 5 (mGlu5) receptor antagonist under clinical development for major depressive disorder (MDD). 2. Six healthy volunteers received a single 1 mg [¹²C/¹⁴C]-basimglurant (2.22 MBq) oral dose and a concomitant i.v. tracer dose of 100 μg of [¹³C₆]-basimglurant. Concentrations of [¹²C]-basimglurant and the stable isotope [¹³C₆]-basimglurant were determined in plasma by a specific LC/MS-MS method. Total [¹⁴C] radioactivity was determined in whole blood, plasma, urine and feces by liquid scintillation counting. Metabolic profiling was conducted in plasma, urine, blood cell pellet and feces samples. 3. The mean absolute bioavailability after oral administration (F) of basimglurant was ∼67% (range 45.7-77.7%). The major route of [¹⁴C]-radioactivity excretion, primarily in form of metabolites, was in urine (mean recovery 73.4%), with the remainder excreted in feces (mean recovery 26.5%). The median t_max for [¹²C]-basimglurant after the oral administration was 0.71 h (range 0.58-1.00) and the mean terminal half-life was 77.2 ± 38.5 h. Terminal half-life for the [¹⁴C]-basimglurant was 178 h indicating presence of metabolites with a longer terminal half-life. Five metabolites were identified with M1-Glucuronide as major and the others in trace amounts. There was minimal binding of drug to RBCs. IV pharmacokinetics was characterized with a mean ± SD CL of 11.8 ± 7.4 mL/h and a Vss of 677 ± 229 L. 4. The double-tracer technique used in this study allowed to simultaneously characterize the absolute bioavailability and disposition characteristics of the new oral molecular entity in a single study.

Role of PTEN-Akt-CREB Signaling Pathway in Nervous System impairment of Rats with Chronic Arsenite Exposure

The nervous system is a target of arsenic toxicity. Phosphatase and tensin homologue deleted on chromosome 10/protein kinase B/cAMP-response element binding protein (PTEN/Akt/CREB) signaling pathway has been reported to be involved in maintaining normal function of the nervous system, modulating growth and proliferation of neurocyte, regulating neuron synaptic plasticity, and long-term memory. And many studies have demonstrated that expressions of PTEN, Akt, and CREB protein were influenced by arsenic, but it is not clear whether this signaling pathway is involved in the nervous system impairment of rats induced by chronic arsenite exposure, and we have addressed this in this study. Eighty male Sprague-Dawley (SD) rats were randomly divided into eight groups (n = 10 each), four groups exposed to NaAsO2 (0, 5, 10, and 50 mg/L NaAsO2 in drinking water) for 3 months, the other four groups exposed to NaAsO2 (0, 5, 10, 50 mg/L NaAsO2 in drinking water) for 6 months. Hematoxylin and eosin (HE) staining showed that chronic arsenite exposure induced varying degrees of damage in cerebral neurons. And arsenite exposure increased arsenic amount in serum and brain samples in a dose- and time-dependent manner. Moreover, the protein levels of PTEN and Akt in brain tissue were not significantly changed compared with the control group, but p-Akt, CREB, and p-CREB were all significantly downregulated in arsenite-exposed groups with a dose-dependent pattern. These results suggested that chronic arsenite exposure negatively regulated the PTEN-Akt-CREB signaling pathway, and dysfunction of the signaling pathway might be one of the mechanisms of nervous system impairment induced by chronic arsenite exposure.

Riluzole combination therapy for moderate-to-severe major depressive disorder: A randomized, double-blind, placebo-controlled trial

Recent evidences suggest that glutamatergic dysregulation implicated in neural plasticity and cellular resilience may contribute to the pathophysiology of Major Depressive Disorder (MDD). Riluzole, which exerts its effect by targeting glutamate neurotransmission, has shown antidepressant effect in recent preclinical, observational and open label studies. This study aimed to assess the efficacy and tolerability of riluzole in patients with MDD. Sixty-four inpatients with diagnosis of moderate to severe major depressive disorder participated in a parallel, randomized, controlled trial, and sixty patients underwent 6 weeks treatment with either riluzole (50 mg/bid) plus citalopram (40 mg/day) or placebo plus citalopram (40 mg/day). All participants were inpatients for the whole duration of the study. Patients were assessed using Hamilton depression rating scale (HDRS) at baseline and weeks 2, 4 and 6. The primary outcome measure was to assess the efficacy of riluzole compared to placebo in improving the depressive symptoms. General linear model repeated measures demonstrated significant effect for time × treatment interaction on HDRS [F (1.86, 107.82) = 8.63, p < 0.001]. Significantly greater improvement was observed in HDRS scores in the riluzole group compared to the placebo group from baseline HDRS score at weeks 2, 4 and 6 (p < 0.001, p = 0.001, p = 0.002, respectively). Significantly greater response with greater speed to treatment was observed in the riluzole group than the placebo group. No serious adverse event occurred. This study showed a favorable safety and efficacy profile in patients with major depressive disorder. Larger controlled studies with longer treatment periods are needed to investigate long term safety, efficacy and optimal dosing.

Treadmill exercise alleviates chronic mild stress-induced depression in rats

Depression is a major cause of disability and one of the most common public health problems. In the present study, antidepressive effect of treadmill exercise on chronic mild stress (CMS)-induced depression in rats was investigated. For this, sucrose intake test, immunohistochemistry for 5-bromo-2'-deoxyuridine, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining, and Western blot analysis for brain-derived neurotrophic factor, cyclic adenosine monophosphate response element binding protein, and endothelial nitric oxide synthase were conducted. Following adaptation to the animal vivarium and two baseline fluid intake tests, the animals were divided into four groups: the control group, the CMS-induced depression group, the CMS-induced depression and exercise group, and the CMS-induced depression and fluoxetine-treated group. The animals in the CMS groups were exposed to the CMS conditions for 8 weeks and those in the control group were exposed to the control conditions for 8 weeks. After 4 weeks of CMS, the rats in the CMS-induced depression and exercise group were made to run on a motorized treadmill for 30 min once a day for 4 weeks. In the present results, treadmill exercise alleviated CMS-induced depressive symptoms. Treadmill exercise restored sucrose consumption, increased cell proliferation, and decreased apoptotic cell death. The present results suggest the possibility that exercise may improve symptoms of depression.

Altered ERK1/2 Signaling in the Brain of Learned Helpless Rats: Relevance in Vulnerability to Developing Stress-Induced Depression

Extracellular signal-regulated kinase 1/2- (ERK1/2-) mediated cellular signaling plays a major role in synaptic and structural plasticity. Although ERK1/2 signaling has been shown to be involved in stress and depression, whether vulnerability to develop depression is associated with abnormalities in ERK1/2 signaling is not clearly known. The present study examined ERK1/2 signaling in frontal cortex and hippocampus of rats that showed vulnerability (learned helplessness, (LH)) or resiliency (non-learned helplessness, (non-LH)) to developing stress-induced depression. In frontal cortex and hippocampus of LH rats, we found that mRNA and protein expressions of ERK1 and ERK2 were significantly reduced, which was associated with their reduced activation and phosphorylation in cytosolic and nuclear fractions, where ERK1 and ERK2 target their substrates. In addition, ERK1/2-mediated catalytic activities and phosphorylation of downstream substrates RSK1 (cytosolic and nuclear) and MSK1 (nuclear) were also lower in the frontal cortex and hippocampus of LH rats without any change in their mRNA or protein expression. None of these changes were evident in non-LH rats. Our study indicates that ERK1/2 signaling is differentially regulated in LH and non-LH rats and suggests that abnormalities in ERK1/2 signaling may be crucial in the vulnerability to developing depression.

Meta-analysis of short- and mid-term efficacy of ketamine in unipolar and bipolar depression

Among treatments currently assessed in major depression, ketamine, has been proposed of great interest, especially because of its very rapid action. However, the time-course of the antidepressive action of ketamine remained unclear. In the present meta-analysis, we provided a clear and objective view regarding the putative antidepressive effect of ketamine and its time-course. We searched the MEDLINE and PsycINFO databases through December 2013, without limits on year of publication, using the key words ketamine and synonyms for mood disorder or episode. Six randomized, double-blind and placebo-controlled trials of ketamine in major depression (n=103 patients) were thus identified. Authors were contacted and they all provided original data necessary for this meta-analysis. Standardized mean differences (SMD) were calculated between the depression scores in ketamine and placebo groups at days 1, 2, 3-4, 7 and 14. Ketamine showed an overall antidepressive efficacy from day 1 to day 7. However, the maintenance of its efficacy over time failed to reach significance in bipolar depression after day 3-4. Significant SMDs were not explained by demographic or clinical characteristics of included samples. The present meta-analysis provides a high level of evidence that ketamine has a rapid antidepressive action during one week, especially in unipolar disorder.

Pathophysiology of major depressive disorder: mechanisms involved in etiology are not associated with clinical progression

Meta-analyses support the involvement of different pathophysiological mechanisms (inflammation, hypothalamic-pituitary (HPA)-axis, neurotrophic growth and vitamin D) in major depressive disorder (MDD). However, it remains unknown whether dysregulations in these mechanisms are more pronounced when MDD progresses toward multiple episodes and/or chronicity. We hypothesized that four central pathophysiological mechanisms of MDD are not only involved in etiology, but also associated with clinical disease progression. Therefore, we expected to find increasingly more dysregulation across consecutive stages of MDD progression. The sample from the Netherlands Study of Depression and Anxiety (18-65 years) consisted of 230 controls and 2333 participants assigned to a clinical staging model categorizing MDD in eight stages (0, 1A, 1B, 2, 3A, 3B, 3C and 4), from familial risk at MDD (stage 0) to chronic MDD (stage 4). Analyses of covariance examined whether pathophysiological mechanism markers (interleukin (IL)-6, C-reactive protein (CRP), cortisol, brain-derived neurotrophic factor and vitamin D) showed a linear trend across controls, those at risk for MDD (stages 0, 1A and 1B), and those with full-threshold MDD (stages 2, 3A, 3B, 3C and 4). Subsequently, pathophysiological differences across separate stages within those at risk and with full-threshold MDD were examined. A linear increase of inflammatory markers (CRP P=0.026; IL-6 P=0.090), cortisol (P=0.025) and decrease of vitamin D (P<0.001) was found across the entire sample (for example, from controls to those at risk and those with full-threshold MDD). Significant trends of dysregulations across stages were present in analyses focusing on at-risk individuals (IL-6 P=0.050; cortisol P=0.008; vitamin D P<0.001); however, no linear trends were found in dysregulations for any of the mechanisms across more progressive stages of full-threshold MDD. Our results support that the examined pathophysiological mechanisms are involved in MDD's etiology. These same mechanisms, however, are less important in clinical progression from first to later MDD episodes and toward chronicity.

Knockdown of PFTK1 Inhibits the Migration of Glioma Cells

The prognosis of glioma patients is generally poor, so it is urgent to find out the underlying molecular mechanisms. PFTK1 is a member of cyclin-dependent kinases (Cdks) family and has been reported to contribute to tumor migration and invasion. In this study, we aimed to explore the expression and function in human glioma. Western blot and immunohistochemistry were used to evaluate the expression of PFTK1. PFTK1 expression was higher in glioma tissues compared with normal brain tissues, and its level was associated with the WHO grade in Western blot analysis. The suppression of PFTK1 expression by RNA interference was shown to inhibit the migration of glioma cells. Knockdown of PFTK1 increases E-cadherin expression and decreases vimentin expression. These data show that PFTK1 may participate in the pathogenic process of glioma, suggesting that PFTK1 can become a potential therapeutic strategy for gastric cancer.

Modes and nodes explain the mechanism of action of vortioxetine, a multimodal agent (MMA): modifying serotonin's downstream effects on glutamate and GABA (gamma amino butyric acid) release

Vortioxetine is an antidepressant with multiple pharmacologic modes of action at targets where serotonin neurons connect with other neurons. These actions modify the release of both glutamate and GABA (gamma amino butyric acid) within various brain circuits.

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

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

Sigma receptors [σRs]: biology in normal and diseased states

This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ₁R) and sigma receptor two (σ₂R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ₁Rs are intracellular receptors acting as chaperone proteins that modulate Ca²⁺ signaling through the IP₃ receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ₁R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K⁺ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ₁R modulation of Ca²⁺ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ₁Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them.

Pathogenesis of depression: Insights from human and rodent studies

Major depressive disorder (MDD) will affect one out of every five people in their lifetime and is the leading cause of disability worldwide. Nevertheless, mechanisms associated with the pathogenesis of MDD have yet to be completely understood and current treatments remain ineffective in a large subset of patients. In this review, we summarize the most recent discoveries and insights for which parallel findings have been obtained in human depressed subjects and rodent models of mood disorders in order to examine the potential etiology of depression. These mechanisms range from synaptic plasticity mechanisms to epigenetics and the immune system where there is strong evidence to support a functional role in the development of specific depression symptomology. Ultimately we conclude by discussing how novel therapeutic strategies targeting central and peripheral processes might ultimately aid in the development of effective new treatments for MDD and related stress disorders.

Antidepressants but not antipsychotics have antiepileptogenic effects with limited effects on comorbid depressive-like behaviour in the WAG/Rij rat model of absence epilepsy

BACKGROUND AND PURPOSE

Two of the most relevant unmet needs in epilepsy are represented by the development of disease-modifying drugs able to affect epileptogenesis and/or the study of related neuropsychiatric comorbidities. No systematic study has investigated the effects of chronic treatment with antipsychotics or antidepressants on epileptogenesis. However, such drugs are known to influence seizure threshold.

EXPERIMENTAL APPROACH

We evaluated the effects of an early long-term treatment (ELTT; 17 weeks), started before seizure onset (P45), with fluoxetine (selective 5-HT-reuptake inhibitor), duloxetine (dual-acting 5-HT-noradrenaline reuptake inhibitor), haloperidol (typical antipsychotic drug), risperidone and quetiapine (atypical antipsychotic drugs) on the development of absence seizures and comorbid depressive-like behaviour in the WAG/Rij rat model. Furthermore, we studied the effects of these drugs on established absence seizures in adult (6-month-old) rats after a chronic 7 weeks treatment.

KEY RESULTS

ELTT with all antipsychotics did not affect the development of seizures, whereas, both ELTT haloperidol (1 mg · kg(-1) day(-1)) and risperidone (0.5 mg · kg(-1) day(-1)) increased immobility time in the forced swimming test and increased absence seizures only in adult rats (7 weeks treatment). In contrast, both fluoxetine (30 mg · kg(-1) day(-1)) and duloxetine (10-30 mg · kg(-1) day(-1)) exhibited clear antiepileptogenic effects. Duloxetine decreased and fluoxetine increased absence seizures in adult rats. Duloxetine did not affect immobility time; fluoxetine 30 mg · kg(-1) day(-1) reduced immobility time while at 10 mg · kg(-1) day(-1) an increase was observed.

CONCLUSIONS AND IMPLICATIONS

In this animal model, antipsychotics had no antiepileptogenic effects and might worsen depressive-like comorbidity, while antidepressants have potential antiepileptogenic effects even though they have limited effects on comorbid depressive-like behaviour.

Inflammation and neuronal plasticity: a link between childhood trauma and depression pathogenesis

During the past two decades, there has been increasing interest in understanding and characterizing the role of inflammation in major depressive disorder (MDD). Indeed, several are the evidences linking alterations in the inflammatory system to Major Depression, including the presence of elevated levels of pro-inflammatory cytokines, together with other mediators of inflammation. However, it is still not clear whether inflammation represents a cause or whether other factors related to depression result in these immunological effects. Regardless, exposure to early life stressful events, which represent a vulnerability factor for the development of psychiatric disorders, act through the modulation of inflammatory responses, but also of neuroplastic mechanisms over the entire life span. Indeed, early life stressful events can cause, possibly through epigenetic changes that persist over time, up to adulthood. Such alterations may concur to increase the vulnerability to develop psychopathologies. In this review we will discuss the role of inflammation and neuronal plasticity as relevant processes underlying depression development. Moreover, we will discuss the role of epigenetics in inducing alterations in inflammation-immune systems as well as dysfunction in neuronal plasticity, thus contributing to the long-lasting negative effects of stressful life events early in life and the consequent enhanced risk for depression. Finally we will provide an overview on the potential role of inflammatory system to aid diagnosis, predict treatment response, enhance treatment matching, and prevent the onset or relapse of Major Depression.

Loss of Glial Cells of the Hippocampus in a Rat Model of Post-traumatic Stress Disorder

Single prolonged stress (SPS) rats is a rodent model of post traumatic stress disorder (PTSD). Abnormal hippocampal morphology and function were found in the PTSD patients. Our previous study has shown that SPS induce loss of hippocampal neurons. But the effects of SPS on glial cells in the hippocampus have not been evaluated. In the present study, wistar male rats were examined at 1, 4, 7, or 14 days after SPS. The morris water maze were performed to examine hippocampal-dependent cognition. The neurometabolite and morphological change in the hippocampal neurons and glial cells were investigated using in vivo proton magnetic resonance spectroscopy and transmission electron microscopy. Immunofluorescence histochemistry and western blotting for Glial fibrillary acidic protein (GFAP) was used to evaluate change of astrocytes. SPS rats showed increased escape latency. The significant reductions in N-acetylaspartate, creatine, and choline-containing compounds in the hippocampus of SPS rats were found. Moreover, abnormal morphological characteristics in glial cells of the SPS group were observed. The number of GFAP-positive cells, intensity of GFAP-ir and GFAP-protein within the hippocampus increased after SPS at 1 day, and then decreased. The findings suggested that SPS induced loss/impairment of glial cell in the hippocampus; also loss of glial cells may due to the astrocytes reduction within the hippocampus of SPS rats.

Alterations of BDNF and trkB mRNA expression in the 6-hydroxydopamine-induced model of preclinical stages of Parkinson's disease: an influence of chronic pramipexole in rats

Our recent study has indicated that a moderate lesion of the mesostriatal and mesolimbic pathways in rats, modelling preclinical stages of Parkinson’s disease, induces a depressive-like behaviour which is reversed by chronic treatment with pramipexole. The purpose of the present study was to examine the role of brain derived neurotrophic factor (BDNF) signalling in the aforementioned model of depression. Therefore, we investigated the influence of 6-hydoxydopamine (6-OHDA) administration into the ventral region of the caudate-putamen on mRNA levels of BDNF and tropomyosin-related kinase B (trkB) receptor. The BDNF and trkB mRNA levels were determined in the nigrostriatal and limbic structures by in situ hybridization 2 weeks after the operation. Pramipexole (1 mg/kg sc twice a day) and imipramine (10 mg/kg ip once a day) were injected for 2 weeks. The lesion lowered the BDNF and trkB mRNA levels in the hippocampus [CA1, CA3 and dentate gyrus (DG)] and amygdala (basolateral/lateral) as well as the BDNF mRNA content in the habenula (medial/lateral). The lesion did not influence BDNF and trkB expression in the caudate-putamen, substantia nigra, nucleus accumbens (shell and core) and ventral tegmental area (VTA). Chronic imipramine reversed the lesion-induced decreases in BDNF mRNA in the DG. Chronic pramipexole increased BDNF mRNA, but decreased trkB mRNA in the VTA in lesioned rats. Furthermore, it reduced BDNF and trkB mRNA expression in the shell and core of the nucleus accumbens, BDNF mRNA in the amygdala and trkB mRNA in the caudate-putamen in these animals. The present study indicates that both the 6-OHDA-induced dopaminergic lesion and chronic pramipexole influence BDNF signalling in limbic structures, which may be related to their pro-depressive and antidepressant activity in rats, respectively.

7-Chlorokynurenic acid (7-CTKA) produces rapid antidepressant-like effects: through regulating hippocampal microRNA expressions involved in TrkB-ERK/Akt signaling pathways in mice exposed to chronic unpredictable mild stress

RATIONALE

7-Chlorokynurenic acid (7-CTKA), a NMDA receptor antagonist, has been reported as a potential rapid antidepressant with poor understanding about the molecular mechanism of its therapeutic action. MicroRNAs (miRNAs) are emerging as critical regulators of central nervous system plasticity and may play an important role in depression.

OBJECTIVE

The objective of this study was to investigate the molecular mechanism of antidepressant action of 7-CTKA in chronic unpredictable mild stress (CUMS) animal model.

METHODS

K252a (tropomyosin-related kinase receptor B (TrkB) antagonist), U0126 (extracellular signal-regulated kinase (ERK) phosphorylation inhibitor), LY294002 (serine-threonine kinase (Akt) phosphorylation inhibitor), or vehicle was given intracerebroventricularly to mice in each group 30 min before 7-CTKA or vehicle intraperitoneal injection. Behavioral changes were observed by sucrose preference test and miRNA microarray was performed to examine hippocampal miRNAs levels in mice. Quantitative RT-PCR was conducted to further confirm results in microarray study.

RESULTS

7-CTKA not only reversed the decrease in sucrose preference and multiple hippocampal miRNAs changes induced by CUMS but also mediated 15 common miRNAs via TrkB-ERK/Akt pathways. Among them, the expression levels of four miRNAs (miR-34a-5p, miR-200a-3p, miR-144-3p, miR-1894-5p) were validated by quantitative real-time PCR (qRT-PCR). The findings from qRT-PCR study support results from microarray analysis except for the non-significance of miR-1894-5p expression.

CONCLUSIONS

This demonstrated that the 15 miRNA targets shared by TrkB-ERK/Akt pathways might participate in rapid-acting molecular mechanism of antidepressant 7-CTKA.

Brain Structural Effects of Antidepressant Treatment in Major Depression

Depressive disorder is a very frequent and heterogeneous syndrome. Structural imaging techniques offer a useful tool in the comprehension of neurobiological alterations that concern depressive disorder. Altered brain structures in depressive disorder have been particularly located in the prefrontal cortex (medial prefrontal cortex and orbitofrontal cortex, OFC) and medial temporal cortex areas (hippocampus). These brain areas belong to a structural and functional network related to cognitive and emotional processes putatively implicated in depressive symptoms. These volumetric alterations may also represent biological predictors of response to pharmacological treatment. In this context, major findings of magnetic resonance (MR) imaging, in relation to treatment response in depressive disorder, will here be presented and discussed.

Is Dysregulation of the HPA-Axis a Core Pathophysiology Mediating Co-Morbid Depression in Neurodegenerative Diseases?

There is increasing evidence of prodromal manifestation of neuropsychiatric symptoms in a variety of neurodegenerative diseases such as Parkinson's disease (PD) and Huntington's disease (HD). These affective symptoms may be observed many years before the core diagnostic symptoms of the neurological condition. It is becoming more apparent that depression is a significant modifying factor of the trajectory of disease progression and even treatment outcomes. It is therefore crucial that we understand the potential pathophysiologies related to the primary condition, which could contribute to the development of depression. The hypothalamic-pituitary-adrenal (HPA)-axis is a key neuroendocrine signaling system involved in physiological homeostasis and stress response. Disturbances of this system lead to severe hormonal imbalances, and the majority of such patients also present with behavioral deficits and/or mood disorders. Dysregulation of the HPA-axis is also strongly implicated in the pathology of major depressive disorder. Consistent with this, antidepressant drugs, such as the selective serotonin reuptake inhibitors have been shown to alter HPA-axis activity. In this review, we will summarize the current state of knowledge regarding HPA-axis pathology in Alzheimer's, PD and HD, differentiating between prodromal and later stages of disease progression when evidence is available. Both clinical and preclinical evidence will be examined, but we highlight animal model studies as being particularly useful for uncovering novel mechanisms of pathology related to co-morbid mood disorders. Finally, we purpose utilizing the preclinical evidence to better inform prospective, intervention studies.

Etiological classification of depression based on the enzymes of tryptophan metabolism

BACKGROUND

Viewed in terms of input and output, the mechanisms of depression are still akin to a black box. However, there must be main pivots for diverse types of depression. From recent therapeutic observations, both the serotonin (5-HT) and kynurenine pathways of tryptophan metabolism may be of particular importance to improved understanding of depression. Here, I propose an etiological classification of depression, based on key peripheral and central enzymes of tryptophan metabolism.

DISCUSSION

Endogenous depression is caused by a larger genetic component than reactive depression. Besides enterochromaffin and mast cells, tryptophan hydroxylase 1 (TPH1), primarily expressed in the gastrointestinal tract, is also found in 5-hydroxytryptophan-producing cells (5-HTP cells) in normal intestinal enterocytes, which are thought to essentially shunt 5-HT production in 5-HT-producing cells. Genetic studies have reported an association between TPH1 and depression, or the responsiveness of depression to antidepressive medication. Therefore, it is possible that hypofunctional 5-HTP cells (reflecting TPH1 dysfunction) in the periphery lead to deficient brain 5-HT levels. Additionally,it has been reported that higher TPH2 expression in depressed suicides may reflect a homeostatic response to deficient 5-HT levels. Subsequently, endogenous depression may be caused by TPH1 dysfunction combined with compensatory TPH2 activation. Reactive depression results from life stresses and involves the hypothalamic-pituitary-adrenal axis, with resulting cortisol production inducing tryptophan 2,3-dioxygenase (TDO) activation. In secondary depression, caused by inflammation, infection, or oxidative stress, indoleamine 2,3-dioxygenase (IDO) is activated. In both reactive and secondary depression, the balance between 3-hydroxykynurenine (3-HK) and kynurenic acid may shift towards 3-HK production via kynurenine-3-monooxygenase (KMO) activation. By shifting the equilibrium position of key enzymes of tryptophan metabolism, the classical classification of depression can be reorganized, as below. Peripheral classification of depression by key enzymes: TPH1 dysfunction, TDO activation, IDO activation. Central classification: TPH2 activation, KMO activation.

SUMMARY

Etiological classification of depression expressed by peripheral (TPH1, TDO, IDO) and central (TPH2, KMO)enzymes of tryptophan metabolism may enable depression to be viewed as a clear box, with the inner components available for inspection and treatment.

Does alexithymia expose to mental disorder symptoms in late adolescence? A 4-year follow-up study

OBJECTIVE

To investigate the possible causal link between alexithymia and the emergence of anxiety and depression symptoms, as well as alcohol consumption in a sample of late adolescents.

METHOD

The nonclinical sample comprised late adolescents (n = 315), including both females (n = 256) and males (n = 59). The follow-up period was 4 years, and at baseline, the mean age of the subjects was 19 years (range 17-21 years). Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20), depression symptoms with the short form of the Beck Depression Inventory (RBDI), anxiety with the State-Trait Anxiety Inventory (STAI) and alcohol consumption with the Alcohol Use Disorders Identification Test (AUDIT). The three TAS-20 subscales were assessed separately. Linear and cumulative logistic regression analyses were used for the evaluation of associations, and the analyses were adjusted with the corresponding baseline scores.

RESULTS

The TAS-20 total and subscale scores did not predict the RBDI or AUDIT scores at follow-up. However, the TAS-20 subscale "difficulty identifying feelings" was significantly associated with both STAI-State (P = .007) and STAI-Trait (P = .004) scores at follow-up.

CONCLUSIONS

Alexithymic features may be individual predictors of later anxiety symptoms. The significant differences between the various dimensions of alexithymia should be considered in future studies.

Effects of lithium and valproic acid on BDNF protein and gene expression in an in vitro human neuron-like model of degeneration

One of the common effects of lithium (Li) and valproic acid (VPA) is their ability to protect against excitotoxic insults. Neurodegenerative and neuropsychiatric diseases may be also associated with altered trophic support of brain-derived neurotrophic factor (BDNF), the most widely distributed neurotrophin in the central nervous system. However, despite these evidences, the effect of Li-VPA combination on BDNF after excitoxic insult has been inadequately investigated. We address this issue by exposing a human neuroblastoma cell line (SH-SY5Y) to neurotoxic concentration of L-glutamate and exploring whether the neuroprotective action of Li-VPA on these cells is associated with changes in BDNF protein and mRNA levels. The results showed that pre-incubation of Li-VPA abolished the toxic effect of glutamate on SH-SY5Y cell survival and this neuroprotective effect was associated with increased synthesis and mRNA expression of BDNF after 24 and 48 h of incubation. In conclusion, this study demonstrates that the neuroprotective effects of Li-VPA against glutamate-induced neurotoxicity in SH-SY5Y neuroblastoma cells is associated with increased synthesis and mRNA expression of BDNF. These data further support the idea that these two drugs can be used for prevention and/or treatment of glutamate-related neurodegenerative disorders.

Bmi-1 regulates the migration and invasion of glioma cells through p16

Bmi-1 is involved in the development of several human cancers; however, its significance in glioma progression remains largely unknown. We report that downregulation of Bmi-1 clearly reduces glioma cell migration and invasion. Downregulation of Bmi-1 promotes the expression of the tumor suppressor p16, which is important in glioma cell motility. Reduction in glioma cell invasion due to downregulation of Bmi-1 could be rescued by p16 downregulation. These results show that Bmi-1 contributes to the motility of glioma cells by regulating the expression of p16.

Inflammation: a mechanism of depression?

In recent decades, major depression has become more prevalent and research has shown that immune activation and cytokine production may be involved. This review is mainly focused on the contribution of inflammation to depression. We first briefly introduce the inflammatory biomarkers of depression, then discuss the sources of cytokines in the brain, and finally describe the neuroimmunological mechanisms underlying the association between inflammation and depression.

Antidepressant-like effect of Ilex paraguariensis in rats

In this study, we investigated the possible antidepressant-like effect of I. paraguariensis in rats. Rats were treated for four weeks with an aqueous extract of I. paraguariensis in drinking water, following the traditional preparation of this beverage. After the period of treatment, behavioral (elevated plus-maze, open field test, and forced swimming test) and biochemical parameters (lipid peroxidation assay, thiol content, vitamin C levels, and monoamine oxidase activity) were evaluated. Animals were also analyzed on forced swimming test after 24 hours of I. paraguariensis intake. An additional group was injected with selegiline 24 hours and 30 minutes before forced swimming test as positive control. HPLC analysis revealed the profile of I. paraguariensis extract. I. paraguariensis reduced the immobility time on forced swimming test without significant changes in locomotor activity in the open field test. Any anxiolytic/anxiogenic effect of I. paraguariensis was observed in rats through the elevated plus-maze test. The antidepressant-like effect of I. paraguariensis was not accompanied by inhibitory effect on monoamine oxidase activity. There were no significant alterations on lipid peroxidation, thiol content, and vitamin C levels among the groups. In conclusion, aqueous extract of I. paraguariensis decreases the time of immobility in rats suggesting an antidepressant-like effect.

Recombinant human erythropoietin for treating treatment-resistant depression: a double-blind, randomized, placebo-controlled phase 2 trial

Pharmacological treatments for depression have insufficient efficacy in 30-40% of patients and fail to reverse cognitive deficits. Erythropoietin (EPO) has neurotrophic actions and aids neurocognitive function. The aim of this exploratory study was to determine whether recombinant human EPO improves mood and memory in treatment-resistant depression. Forty treatment-resistant depressed unipolar patients with Hamilton Depression Rating Scale-17 (HDRS-17) score ≥ 17 were randomized to eight weekly EPO (Eprex; 40,000 IU) or saline infusions in a double-blind, placebo-controlled, parallel-group design. Patients were assessed at baseline and at weeks 5, 9, and 14. Primary outcome was reduction in HDRS-17 score. Global assessment of function (GAF) was reported in addition. Secondary outcome was remission rate, and tertiary outcomes were changes in Rey Auditory Verbal Learning Test (RAVLT), Beck Depression Inventory-21 (BDI-21), and World Health Organization Quality of life-BREF (WHOQOL-BREF). Exploratory outcomes were depression and cognition composite scores. HDRS-17, GAF, and remission rates showed no effects of EPO over saline at week 9 (P-value ≥ 0.09). However, EPO improved BDI (P=0.02) and WHOQOL-BREF (P=0.01), and this was maintained at follow-up week 14 (P-values ≤ 0.04). EPO enhanced verbal recall (P=0.02) and recognition (P=0.03), which was sustained at follow-up (P-values ≤ 0.04). Exploratory analysis in patients fulfilling depression severity criteria at trial start revealed ameliorated HDRS-17 in EPO (N=14) vs saline groups (N=17), which was sustained at week 14 (P-values ≤ 0.05). Exploratory analysis in the complete cohort showed that EPO reduced depression composite at weeks 9 and 14 (P-values=0.02). The findings of this exploratory study highlight EPO as an interesting compound for treatment-resistant depression, which deserves further investigation.