Effects of acute and chronic treatment elicited by lamotrigine on behavior, energy metabolism, neurotrophins and signaling cascades in rats

Signaling Pathways Concerning Mitochondrial Dysfunction: Implications in Neurodegeneration and Possible Molecular Targets

Mitochondrion is an important organelle present in our cells responsible for meeting energy requirements. All higher organisms rely on efficient mitochondrial bioenergetic machinery to sustain life. No other respiratory process can produce as much power as generated by mitochondria in the form of ATPs. This review is written in order to get an insight into the magnificent working of mitochondrion and its implications in cellular homeostasis, bioenergetics, redox, calcium signaling, and cell death. However, if this machinery gets faulty, it may lead to several disease states. Mitochondrial dysfunctioning is of growing concern today as it is seen in the pathogenesis of several diseases which includes neurodegenerative disorders, cardiovascular disorders, diabetes mellitus, skeletal muscle defects, liver diseases, and so on. To cover all these aspects is beyond the scope of this article; hence, our study is restricted to neurodegenerative disorders only. Moreover, faulty functioning of this organelle can be one of the causes of early ageing in individuals. This review emphasizes mutations in the mitochondrial DNA, defects in oxidative phosphorylation, generation of ROS, and apoptosis. Researchers have looked into new approaches that might be able to control mitochondrial failure and show a lot of promise as treatments.

Neuroprotective Properties of Antiepileptics: What are the Implications for Psychiatric Disorders?

Since the discovery of the first antiepileptic compound, increasing attention has been paid to antiepileptic drugs (AEDs), and recently, with the understanding of the molecular mechanism underlying cells death, a new interest has revolved around a potential neuroprotective effect of AEDs. While many neurobiological studies in this field have focused on the protection of neurons, growing data are reporting how exposure to AEDs can also affect glial cells and the plastic response underlying recovery; however, demonstrating the neuroprotective abilities of AEDs remains a changeling task. The present work aims to summarize and review the literature available on the neuroprotective properties of the most commonly used AEDs. Results highlighted how further studies should investigate the link between AEDs and neuroprotective properties; while many studies are available on valproate, results for other AEDs are very limited and the majority of the research has been carried out on animal models. Moreover, a better understanding of the biological basis underlying neuro-regenerative defects may pave the way for the investigation of further therapeutic targets and eventually lead to an improvement in the actual treatment strategies.

Serotonin Type 3 Receptor Is Potentially Involved in Cellular Stress Induced by Hydrogen Peroxide

Depression is a disease with several molecular mechanisms involved, such as problems in the serotonergic pathway. This disease is very complex and prevalent, and thus important to deeply study and aim to overcome high rates of relapse and therapeutic failure. In this study, two cellular lines were used (HT-22 and SH-SY5Y cells) to gain insight about the role of the serotonin type 3 (5-HT3) receptor in cellular stress induced by hydrogen peroxide and/or corticosterone. In research, these compounds are known to mimic the high levels of oxidative stress and dysfunction of the hypothalamus–hypophysis–adrenal axis by the action of glucocorticoids, usually present in depressed individuals. The receptor 5-HT3 is also known to be involved in depression, previously demonstrated in studies that highlight the role of these receptors as promising targets for antidepressant therapy. Indeed, the drugs used in this work (mirtazapine, scopolamine, and lamotrigine) interact with this serotonergic receptor. Thus, by using cell morphology, cell viability (neutral red and MTT), and HPLC assays, this work aimed to understand the role of these drugs in the stress induced by H₂O₂/corticosterone to HT-22 and SH-SY5Y cell lines. We concluded that the antagonism of the 5-HT3 receptor by these drugs may be important in the attenuation of H₂O₂-induced oxidative stress to the cells, but not in the corticosterone-induced stress.

Profiling the Skeletal Muscle Proteome in Patients on Atypical Antipsychotics and Mood Stabilizers

Atypical antipsychotics (AAP) are used in the treatment of severe mental illness. They are associated with several metabolic side effects including insulin resistance. The skeletal muscle is the primary tissue responsible for insulin-stimulated glucose uptake. Dysfunction of protein regulation within the skeletal muscle following treatment with AAPs may play a role in the associated metabolic side effects. The objective of this study was to measure protein abundance in the skeletal muscle of patients on long-term AAP or mood stabilizer treatment. Cross-sectional muscle biopsies were obtained from patients with bipolar disorder and global protein abundance was measured using stable isotope labeling by amino acid (SILAC) combined with high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Sixteen patients completed muscle biopsies and were included in the proteomic analyses. A total of 40 proteins were significantly different between the AAP group and the mood stabilizer group. In-silico pathway analysis identified significant enrichment in several pathways including glucose metabolism, cell cycle, apoptosis, and folate metabolism. Proteome abundance changes also differed based on protein biological processes and function. In summary, significant differences in proteomic profiles were identified in the skeletal muscle between patients on AAPs and mood stabilizers. Future work is needed to validate these findings in prospectively sampled populations.

Investigation of the Roles of New Antiepileptic Drugs and Serum BDNF Levels in Efficacy and Safety Monitoring and Quality of Life: A Clinical Research

Objective: We aimed to determine the therapeutic drug monitoring (TDM) features and the relation to Brain-Derived Neurotrophic Factor (BDNF) of frequently used new antiepileptic drugs (NADs) including lamotrigine (LTG), oxcarbazepine (OXC), zonisamide (ZNS) and lacosamide (LCM). Moreover, we investigated their effect on the quality of life (QoL).

Methods: Eighty epileptic patients who had been using the NADs, and thirteen healthy participants were included in this cross-sectional study. The participants were randomized into groups. The QOLIE-31 test was used for the assessment of QoL. We also prepared and applied “Safety Test”. HPLC method for TDM, and ELISA method for BDNF measurements were used consecutively.

Results: In comparison to healthy participants, epileptic participants had lower marriage rate (p=0.049), education level (p˂0.001), alcohol use (p=0.002). BDNF levels were higher in patients with focal epilepsy (p=0.013) and in those with higher education level (p=0.016). There were negative correlations between serum BDNF levels and serum ZNS levels (p=0.042) with LTG-polytherapy, serum MHD levels (a 10-monohydroxy derivative of OXC, p=0.041) with OXC-monotherapy. There was no difference in BDNF according to monotherapy-polytherapy, drug-resistant groups, regarding seizure frequency. There was a positive correlation between total health status and QoL (p˂0.001). QOLIE-31 overall score (OS) was higher in those with OXC-monotherapy (76.5±14.5). OS (p˂0.001), seizure worry (SW, p=0.004), cognition (C, p˂0.001), social function (SF, p˂0.001) were different in the main groups. Forgetfulness was the most common unwanted effect.

Conclusion: While TDM helps the clinician to use more effective and safe NADs, BDNF may assist in TDM for reaching the therapeutic target in epilepsy.

Effect of neuropsychiatric medications on mitochondrial function: For better or for worse

Individuals with mitochondrial disease often present with psychopathological comorbidity, and mitochondrial dysfunction has been proposed as the underlying pathobiology in various psychiatric disorders. Several studies have suggested that medications used to treat neuropsychiatric disorders could directly influence mitochondrial function. This review provides a comprehensive overview of the effect of these medications on mitochondrial function. We collected preclinical information on six major groups of antidepressants and other neuropsychiatric medications and found that the majority of these medications either positively influenced mitochondrial function or showed mixed effects. Only amitriptyline, escitalopram, and haloperidol were identified as having exclusively adverse effects on mitochondrial function. In the absence of formal clinical trials, and until such trials are completed, the data from preclinical studies reported and discussed here could inform medication prescribing practices for individuals with psychopathology and impaired mitochondrial function in the underlying pathology.

Role of 5-HT1A and 5-HT2C receptors of the dorsal periaqueductal gray in the anxiety- and panic-modulating effects of antidepressants in rats

Antidepressant drugs are first-line treatment for panic disorder. Facilitation of 5-HT_1A receptor-mediated neurotransmission in the dorsal periaqueductal gray (dPAG), a key panic-associated area, has been implicated in the panicolytic effect of the selective serotonin reuptake inhibitor fluoxetine. However, it is still unknown whether this mechanism accounts for the antipanic effect of other classes of antidepressants drugs (ADs) and whether the 5-HT interaction with 5-HT_2C receptors in this midbrain area (which increases anxiety) is implicated in the anxiogenic effect caused by short-term treatment with ADs. The results showed that previous injection of the 5-HT_1A receptor antagonist WAY-100635 in the dPAG blocked the panicolytic-like effect caused by chronic systemic administration of the tricyclic AD imipramine in male Wistar rats tested in the elevated T-maze. Neither chronic treatment with imipramine nor fluoxetine changed the expression of 5-HT_1A receptors in the dPAG. Treatment with these ADs also failed to significantly change ERK1/2 (extracellular-signal regulated kinase) phosphorylation level in this midbrain area. Blockade of 5-HT_2C receptors in the dPAG with the 5-HT_2C receptor antagonist SB-242084 did not change the anxiogenic effect caused by a single acute injection of fluoxetine or imipramine in the Vogel conflict test. These results reinforce the view that the facilitation of 5-HT_1A receptor-mediated neurotransmission in the dPAG is a common mechanism involved in the panicolytic effect caused by chronic administration of ADs. On the other hand, the anxiogenic effect observed after short-term treatment with these drugs does not depend on 5-HT_2C receptors located in the dPAG.

Psychotropic and neurological medication effects on mitochondrial complex I and IV in rodent models

Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported to be affected by drugs used to treat psychiatric or neurodegenerative diseases, including antidepressants, antipsychotics, anxiolytics, mood stabilizers, stimulants, antidementia, and antiparkinsonian drugs. We conducted meta-analyses examining the effects of each drug category on complex I and IV. The electronic databases Pubmed, EMBASE, CENTRAL, and Google Scholar were searched for studies published between 1970 and 2018. Of 3105 screened studies, 68 articles covering 53 drugs were included in the meta-analyses. All studies assessed complex I and IV in rodent brain at the level of enzyme activity. Results revealed that selected antidepressants increase or decrease complex I and IV, antipsychotics and stimulants decrease complex I but increase complex IV, whereas anxiolytics, mood stabilizers, antidementia, and antiparkinsonian drugs preserve or even enhance both complex I and IV. Potential contributions to the drug effects were found to be related to the drugs' neurotransmitter receptor profiles with adrenergic (α1B), dopaminergic (D1/2), glutaminergic (NMDA1,3), histaminergic (H1), muscarinic (M1,3), opioid (OP1-3), serotonergic (5-HT_2A, 5-HT_2C, 5-HT_3A) and sigma (σ1) receptors having the greatest effects. The findings are discussed in relation to pharmacological mechanisms of action that might have relevance for clinical and research applications.

Complex Combination Pharmacotherapy for Bipolar Disorder: Knowing When Less Is More or More Is Better

Combination pharmacotherapy for bipolar disorder is commonplace and often reflects the severity and complexity of the illness and the comorbid conditions frequently associated with it. Across treatment settings, about one-fifth of patients with bipolar disorder appear to receive four or more psychotropic medications. Practice patterns often outpace the evidence-based literature, insofar as few systematic studies have examined the efficacy and safety of two or more medications for any given phase of illness. Most randomized trials of combination pharmacotherapy focus on the utility of pairing a mood stabilizer with a second-generation antipsychotic for prevention of either acute mania or relapse. In real-world practice, patients with bipolar disorder often take more elaborate combinations of mood stabilizers, antipsychotics, antidepressants, anxiolytics, stimulants, and other psychotropics for indefinite periods that do not necessarily arise purposefully and logically. In this article, I identify clinical factors associated with complex combination pharmacotherapy for patients with bipolar disorder; describe approaches to ensuring that each component of a treatment regimen has a defined role; discuss the elimination of unnecessary, ineffective, or redundant drugs in a regimen; and address complementary, safe, rationale-based drug combinations that target specific domains of psychopathology for which monotherapies often provide inadequate benefit.

The possible beneficial effects of creatine for the management of depression

Depression, a highly prevalent neuropsychiatric disorder worldwide, causes a heavy burden for the society and is associated with suicide risk. The treatment of this disorder remains a challenge, since currently available antidepressants provide a slow and, often, incomplete response and cause several side effects that contribute to diminish the adhesion of patients to treatment. In this context, several nutraceuticals have been investigated regarding their possible beneficial effects for the management of this neuropsychiatric disorder. Creatine stands out as a supplement frequently used for ergogenic purpose, but it also is a neuroprotective compound with potential to treat or mitigate a broad range of central nervous systems diseases, including depression. This review presents preclinical and clinical evidence that creatine may exhibit antidepressant properties. The focus is given on the possible molecular mechanisms underlying its effects based on the results obtained with different animal models of depression. Finally, evidence obtained in animal models of depression addressing the possibility that creatine may produce rapid antidepressant effect, similar to ketamine, are also presented and discussed.

Lamotrigine as a mood stabilizer: insights from the pre-clinical evidence

INTRODUCTION

Lamotrigine (LTG) is a well-established anticonvulsant that is also approved for the prevention of mood relapses in bipolar disorder. However, the mechanisms underlying LTG mood stabilizing effects remain unclear. Areas covered: Herein, the pre-clinical evidence concerning LTG's' mode of action in depression and mania is reviewed. Bottlenecks and future perspectives for this expanding and promising field are also discussed. Pre-clinical studies have indicated that neurotransmitter systems, especially serotoninergic, noradrenergic and glutamatergic, as well as non-neurotransmitter pathways such as inflammation and oxidative processes might play a role in LTG's antidepressant effects. The mechanisms underlying LTG's anti-manic properties remain to be fully explored, but the available pre-clinical evidence points out to the role of glutamatergic neurotransmission, possibly through AMPA-receptors. Expert opinion: A major limitation of current pre-clinical investigations is that there are no experimental models that recapitulate the complexity of bipolar disorder. Significant methodological differences concerning time and dose of LTG treatment, administration route, animal strains, and behavioral paradigms also hamper the reproducibility of the findings, leading to contradictory conclusions. Moreover, the role of other mechanisms (e.g. inositol phosphate and GSK3β pathways) implicated in the mode of action of different mood-stabilizers must also be consolidated with LTG.

Pharmacological and neuroethological study of the acute and chronic effects of lamotrigine in the genetic audiogenic seizure hamster (GASH:Sal)

The present study aimed to investigate the behavioral and anticonvulsant effects of lamotrigine (LTG) on the genetic audiogenic seizure hamster (GASH:Sal), an animal model of audiogenic seizure that is in the validation process. To evaluate the efficiency of acute and chronic treatments with LTG, GASH:Sals were treated with LTG either acutely via intraperitoneal injection (5-20mg/kg) or chronically via oral administration (20-25mg/kg/day). Their behavior was assessed via neuroethological analysis, and the anticonvulsant effect of LTG was evaluated based on the appearance and the severity of seizures. The results showed that acute administration of LTG exerts an anticonvulsant effect at the lowest dose tested (5mg/kg) and that chronic oral LTG treatment exerts an anticonvulsant effect at a dose of 20-25mg/kg/day. Furthermore, LTG treatment induced a low rate of secondary adverse effects. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Brain Structural Effects of Psychopharmacological Treatment in Bipolar Disorder

Bipolar disorder is associated with subtle neuroanatomical deficits including lateral ventricular enlargement, grey matter deficits incorporating limbic system structures, and distributed white matter pathophysiology. Substantial heterogeneity has been identified by structural neuroimaging studies to date and differential psychotropic medication use is potentially a substantial contributor to this. This selective review of structural neuroimaging and diffusion tensor imaging studies considers evidence that lithium, mood stabilisers, antipsychotic medication and antidepressant medications are associated with neuroanatomical variation. Most studies are negative and suffer from methodological weaknesses in terms of directly assessing medication effects on neuroanatomy, since they commonly comprise posthoc assessments of medication associations with neuroimaging metrics in small heterogenous patient groups. However the studies which report positive findings tend to form a relatively consistent picture whereby lithium and antiepileptic mood stabiliser use is associated with increased regional grey matter volume, especially in limbic structures. These findings are further supported by the more methodologically robust studies which include large numbers of patients or repeated intra-individual scanning in longitudinal designs. Some similar findings of an apparently ameliorative effect of lithium on white matter microstructure are also emerging. There is less support for an effect of antipsychotic or antidepressant medication on brain structure in bipolar disorder, but these studies are further limited by methodological difficulties. In general the literature to date supports a normalising effect of lithium and mood stabilisers on brain structure in bipolar disorder, which is consistent with the neuroprotective characteristics of these medications identified by preclinical studies.

Lamotrigine Reduces β-Site AβPP-Cleaving Enzyme 1 Protein Levels Through Induction of Autophagy

Lamotrigine (LTG), a broad-spectrum anti-epileptic drug widely used in treatment for seizures, shows potential efficacy in Alzheimer's disease (AD) therapy. Chronic LTG treatment rescues the suppressed long-term potentiation, loss of spines and cognitive deficits in AβPP/PS1 mice, known to overexpress a chimeric mouse/human mutant amyloid-β protein precursor (AβPP) and a mutant human presenilin 1 (PS1). These changes are accompanied by reduction of amyloid-β (Aβ) plaques density and of levels of β-C-terminal fragment of AβPP (β-CTF), a fragment of AβPP cleaved by β-secretase. These results suggest LTG treatment reduces Aβ production, possibly through modulation of cleavage of AβPP by β-secretase. However, the underlying mechanisms still remain unclear. In this study, decreased protein levels, but not mRNA levels of β-site AβPP-cleaving enzyme 1 (BACE1), were observed in cultured HEK293 cells and the brains of AβPP/PS1 transgenic mice upon LTG treatment. Moreover, LTG treatment suppressed mammalian target of rapamycin (mTOR) signaling, while enhancing activation of cAMP response element binding protein (CREB), two signaling pathways essential for autophagy induction. LTG treatment increased the numbers of LC3-GFP + puncta and LC3-II levels in HEK293 cells, indicating an induction of autophagy. The downregulation of BACE1 by LTG treatment was prevented by the autophagy inhibitor 3-Methyladenine. Therefore, this study shows that LTG treatment reduces the protein levels of BACE1 through activation of autophagy, possibly via inhibition of mTOR signaling and activation of CREB.

Enriched Flavonoid Fraction from Cecropia pachystachya Trécul Leaves Exerts Antidepressant-like Behavior and Protects Brain Against Oxidative Stress in Rats Subjected to Chronic Mild Stress

The purpose of this study was to assess the effect of an enriched C-glycosyl flavonoids fraction (EFF-Cp) from Cecropia Pachystachya leaves on behavior, mitochondrial chain function, and oxidative balance in the brain of rats subjected to chronic mild stress. Male Wistar rats were divided into experimental groups (saline/no stress, saline/stress, EFF-Cp/no stress, and EFF-Cp/stress). ECM groups were submitted to stress for 40 days. On the 35th ECM day, EFF-Cp (50 mg/kg) or saline was administrated and the treatments lasted until the 42nd day. On the 41st and 42nd days, the animals were submitted to the splash test and the forced swim test. After these behavioral tests, the enzymatic activity of mitochondrial chain complexes and oxidative stress were analyzed. EFF-Cp reversed the depressive-like behavior induced by ECM. It also reversed the increase in thiobarbituric acid reactive species, myeloperoxidase activity, and nitrite/nitrate concentrations in some brain regions. The reduced activities of the antioxidants superoxide dismutase and catalase in some brain regions were also reversed by EFF-Cp. The most pronounced effect of EFF-Cp on mitochondrial complexes was an increase in complex IV activity in all studied regions. Thus, it is can be concluded that EFF-Cp exerts an antidepressant-like effect and that oxidative balance may be an important physiological process underlying these effects.

FXR1P is a GSK3β substrate regulating mood and emotion processing

Inhibition of glycogen synthase kinase 3β (GSK3β) is a shared action believed to be involved in the regulation of behavior by psychoactive drugs such as antipsychotics and mood stabilizers. However, little is known about the identity of the substrates through which GSK3β affects behavior. We identified fragile X mental retardation-related protein 1 (FXR1P), a RNA binding protein associated to genetic risk for schizophrenia, as a substrate for GSK3β. Phosphorylation of FXR1P by GSK3β is facilitated by prior phosphorylation by ERK2 and leads to its down-regulation. In contrast, behaviorally effective chronic mood stabilizer treatments in mice inhibit GSK3β and increase FXR1P levels. In line with this, overexpression of FXR1P in the mouse prefrontal cortex also leads to comparable mood-related responses. Furthermore, functional genetic polymorphisms affecting either FXR1P or GSK3β gene expression interact to regulate emotional brain responsiveness and stability in humans. These observations uncovered a GSK3β/FXR1P signaling pathway that contributes to regulating mood and emotion processing. Regulation of FXR1P by GSK3β also provides a mechanistic framework that may explain how inhibition of GSK3β can contribute to the regulation of mood by psychoactive drugs in mental illnesses such as bipolar disorder. Moreover, this pathway could potentially be implicated in other biological functions, such as inflammation and cell proliferation, in which FXR1P and GSK3 are known to play a role.

Effect of fluoxetine treatment on mitochondrial bioenergetics in central and peripheral rat tissues

Recent investigations have focused on the mitochondrion as a direct drug target in the treatment of metabolic diseases (obesity, metabolic syndrome). Relatively few studies, however, have explicitly investigated whether drug therapies aimed at changing behavior by altering central nervous system (CNS) function affect mitochondrial bioenergetics, and none has explored their effect during early neonatal development. The present study was designed to evaluate the effects of chronic treatment of newborn male rats with the selective serotonin reuptake inhibitor fluoxetine on the mitochondrial bioenergetics of the hypothalamus and skeletal muscle during the critical nursing period of development. Male Wistar rat pups received either fluoxetine (Fx group) or vehicle solution (Ct group) from the day of birth until 21 days of age. At 60 days of age, mitochondrial bioenergetics were evaluated. The Fx group showed increased oxygen consumption in several different respiratory states and reduced production of reactive oxygen species, but there was no change in mitochondrial permeability transition pore opening or oxidative stress in either the hypothalamus or skeletal muscle. We observed an increase in glutathione S-transferase activity only in the hypothalamus of the Fx group. Taken together, our results suggest that chronic exposure to fluoxetine during the nursing phase of early rat development results in a positive modulation of mitochondrial respiration in the hypothalamus and skeletal muscle that persists into adulthood. Such long-lasting alterations in mitochondrial activity in the CNS, especially in areas regulating appetite, may contribute to permanent changes in energy balance in treated animals.

Minocycline protects against oxidative damage and alters energy metabolism parameters in the brain of rats subjected to chronic mild stress

Studies have been suggested that minocycline can be a potential new agent for the treatment of depression. In addition, both oxidative stress and energy metabolism present an important role in pathophysiology of depression. So, the present study was aimed to evaluate the effects of minocycline on stress oxidative parameters and energy metabolism in the brain of adult rats submitted to the chronic mild stress protocol (CMS). After CMS Wistar, both stressed animals as controls received twice ICV injection of minocycline (160 μg) or vehicle. The oxidative stress and energy metabolism parameters were assessed in the prefrontal cortex (PF), hippocampus (HIP), amygdala (AMY) and nucleus accumbens (Nac). Our findings showed that stress induced an increase on protein carbonyl in the PF, AMY and NAc, and mynocicline injection reversed this alteration. The TBARS was increased by stress in the PF, HIP and NAc, however, minocycline reversed the alteration in the PF and HIP. The Complex I was incrased in AMY by stress, and minocycline reversed this effect, however reduced Complex I activity in the NAc; Complex II reduced in PF and AMY by stress or minocycline; the Complex II-III increased in the HIP in stress plus minocycline treatment and in the NAc with minocycline; in the PF and HIP there were a reduced in Complex IV with stress and minocycline. The creatine kinase was reduced in AMY and NAc with stress and minocycline. In conclusion, minocycline presented neuroprotector effects by reducing oxidative damage and regulating energy metabolism in specific brain areas.

White matter alterations in bipolar disorder: potential for drug discovery and development

OBJECTIVES

Brain white matter (WM) alterations have recently emerged as potentially relevant in bipolar disorder. New techniques such as diffusion tensor imaging allow precise exploration of these WM microstructural alterations in bipolar disorder. Our objective was to critically review WM alterations in bipolar disorder, using neuroimaging and neuropathological studies, in the context of neural models and the potential for drug discovery and development.

METHODS

We conducted a systematic PubMed and Google Scholar search of the WM and bipolar disorder literature up to and including January 2013.

RESULTS

Findings relating to WM alterations are consistent in neuroimaging and neuropathology studies of bipolar disorder, especially in regions involved in emotional processing such as the anterior frontal lobe, corpus callosum, cingulate cortex, and in fronto-limbic connections. Some of the structural alterations are related to genetic risk factors for bipolar disorder and may underlie the dysfunctional emotional processing described in recent neurobiological models of bipolar disorder. Medication effects in bipolar disorder, from lithium and other mood stabilizers, might impact myelinating processes, particularly by inhibition of glycogen synthase kinase-3 beta.

CONCLUSIONS

Pathways leading to WM alterations in bipolar disorder represent potential targets for the development and discovery of new drugs. Myelin damage in bipolar disorder suggests that the effects of existing pro-myelinating drugs should also be evaluated to improve our understanding and treatment of this disease.

β-Carboline harmine reverses the effects induced by stress on behaviour and citrate synthase activity in the rat prefrontal cortex

OBJECTIVES

The present study was aimed at evaluating the effects of the administration of β-carboline harmine on behaviour and citrate synthase activity in the brain of rats exposed to chronic mild stress (CMS) procedure.

METHODS

To this aim, after 40 days of exposure to CMS procedure, rats were treated with harmine (15 mg/kg/day) for 7 days, then memory, anhedonia and citrate synthase activity were assessed. Result Our findings demonstrated that stressed rats treated with saline increased the sucrose intake, and the stressed rats treated with harmine reversed this effect. Neither stress nor harmine treatment altered memory performance in rats. In addition, chronic stressful situations induced increase in citrate synthase activity in the prefrontal cortex, but not in the hippocampus and striatum. Treatment with harmine reversed the increase in citrate synthase activity in the prefrontal cortex.

CONCLUSION

These findings support the hypothesis that harmine could be involved in controlling the energy metabolism.

Mitochondrial dysfunction in epilepsy

Epilepsy is the most common neurologic disorder worldwide and is characterized by recurrent unprovoked seizures. The mitochondrial (mt) respiratory chain is the final common pathway for cellular energy production through the process of oxidative phosphorylation. As neurons are terminally differentiated cells that lack significant regenerative capacity and have a high energy demand, they are more vulnerable to mt dysfunction. Therefore, epileptic seizures have been well described in several diseases such as mt encephalomyopathy, lactic acidosis, and stroke-like episodes and myoclonic epilepsy and ragged red fibers, which are caused by gene mutations in mtDNA, among others. Mutations in nuclear DNA regulating mt function are also being described (eg, POLG gene mutation). The role of mitochondria (mt) in acquired epilepsies, which account for about 60% of all epilepsies, is equally important but less well understood. Oxidative stress is one of the possible mechanisms in the pathogenesis of epilepsy resulting from mt dysfunction gradually disrupting the intracellular Ca(2+) homeostasis, which modulates neuronal excitability and synaptic transmission, making neurons more vulnerable to additional stress, and leading to energy failure and neuronal loss in epilepsy. Antiepileptic drugs (AEDs) also affect mt function in several ways. There must be caution when treating epilepsy in patients with known mt disorders as some AEDs are toxic to the mt. This review summarizes our current knowledge of the effect of mt disorders on epilepsy, of epileptic seizures on mt, and of AEDs on mt function and the implications of all these interactions for the management of epilepsy in patients with or without mt disease.

Intracellular pathways of antipsychotic combined therapies: implication for psychiatric disorders treatment

Dysfunctions in the interplay among multiple neurotransmitter systems have been implicated in the wide range of behavioral, emotional and cognitive symptoms displayed by major psychiatric disorders, such as schizophrenia, bipolar disorder or major depression. The complex clinical presentation of these pathologies often needs the use of multiple pharmacological treatments, in particular (1) when monotherapy provides insufficient improvement of the core symptoms; (2) when there are concurrent additional symptoms requiring more than one class of medication and (3) in order to improve tolerability, by using two compounds below their individual dose thresholds to limit side effects. To date, the choice of drug combinations is based on empirical paradigm guided by clinical response. Nonetheless, several preclinical studies have demonstrated that drugs commonly used to treat psychiatric disorders may impact common intracellular target molecules (e.g. Akt/GSK-3 pathway, MAP kinases pathway, postsynaptic density proteins). These findings support the hypothesis that convergence at crucial steps of transductional pathways could be responsible for synergistic effects obtained in clinical practice by the co-administration of those apparently heterogeneous pharmacological compounds. Here we review the most recent evidence on the molecular crossroads in antipsychotic combined therapies with antidepressants, mood stabilizers, and benzodiazepines, as well as with antipsychotics. We first discuss clinical clues and efficacy of such combinations. Then we focus on the pharmacodynamics and on the intracellular pathways underpinning the synergistic, or concurrent, effects of each therapeutic add-on strategy, as well as we also critically appraise how pharmacological research may provide new insights on the putative molecular mechanisms underlying major psychiatric disorders.

Synaptic plasticity in depression: molecular, cellular and functional correlates

Synaptic plasticity confers environmental adaptability through modification of the connectivity between neurons and neuronal circuits. This is achieved through changes to synapse-associated signaling systems and supported by complementary changes to cellular morphology and metabolism within the tripartite synapse. Mounting evidence suggests region-specific changes to synaptic form and function occur as a result of chronic stress and in depression. Within subregions of the prefrontal cortex (PFC) and hippocampus structural and synapse-related findings seem consistent with a deficit in long-term potentiation (LTP) and facilitation of long-term depression (LTD), particularly at excitatory pyramidal synapses. Other brain regions are less well-studied; however the amygdala may feature a somewhat opposite synaptic pathology including reduced inhibitory tone. Changes to synaptic plasticity in stress and depression may correlate those to several signal transduction pathways (e.g. NOS-NO, cAMP-PKA, Ras-ERK, PI3K-Akt, GSK-3, mTOR and CREB) and upstream receptors (e.g. NMDAR, TrkB and p75NTR). Deficits in synaptic plasticity may further correlate disrupted brain redox and bioenergetics. Finally, at a functional level region-specific changes to synaptic plasticity in depression may relate to maladapted neurocircuitry and parallel reduced cognitive control over negative emotion.

Chronic administration of duloxetine and mirtazapine downregulates proapoptotic proteins and upregulates neurotrophin gene expression in the hippocampus and cerebral cortex of mice

Structural alterations in the limbic system, neuronal cell loss, and low levels of neurotrophins have been implicated in the pathogenesis of depression. While it is generally accepted that increasing monoamine levels in the brain can effectively alleviate depression, the precise neurobiological mechanisms involved are unclear. In the present study, we examined the effects of two antidepressants, duloxetine and mirtazapine, on the expression of apoptotic and neurotrophic proteins in the cerebral cortex and hippocampus of mice. Duloxetine (10 mg/kg) and mirtazapine (3 mg/kg) were chronically administered for 21 days, and qRT-PCR analysis was carried for the following: neurotrophins (BDNF, NGF, FGF-2, and NT-3); anti-apoptotic proteins (Bcl-2 and Bcl-xL) and pro-apoptotic proteins (Bax, Bad, and p53). Both duloxetine and mirtazapine produced antidepressant activity in the forced swimming test and induced increased cortical and hippocampal mRNA expression of BDNF. Duloxetine also increased Bcl-2, Bcl-xL, FGF-2, and NT-3 expression in the cerebral cortex, and FGF-2 expression in the hippocampus. Moreover, duloxetine reduced Bax and p53 expression in the hippocampus, and Bad expression in the cerebral cortex. Mirtazapine decreased Bcl-xL and Bax expression in the hippocampus, and Bad and p53 expression in both the hippocampus and cerebral cortex. Mirtazapine also increased the expression of neurotrophins, NGF and NT-3, in the cerebral cortex. These results suggest that duloxetine and mirtazapine could elicit their therapeutic effect by modulating the activity of apoptotic and neurotrophic pathways, thus enhancing plasticity and cell survival in depressive patients.

Treatment with tianeptine induces antidepressive-like effects and alters the neurotrophin levels, mitochondrial respiratory chain and cycle Krebs enzymes in the brain of maternally deprived adult rats

Maternally deprived rats were treated with tianeptine (15 mg/kg) once a day for 14 days during their adult phase. Their behavior was then assessed using the forced swimming and open field tests. The BDNF, NGF and energy metabolism were assessed in the rat brain. Deprived rats increased the immobility time, but tianeptine reversed this effect and increased the swimming time; the BDNF levels were decreased in the amygdala of the deprived rats treated with saline and the BDNF levels were decreased in the nucleus accumbens within all groups; the NGF was found to have decreased in the hippocampus, amygdala and nucleus accumbens of the deprived rats; citrate synthase was increased in the hippocampus of non-deprived rats treated with tianeptine and the creatine kinase was decreased in the hippocampus and amygdala of the deprived rats; the mitochondrial complex I and II-III were inhibited, and tianeptine increased the mitochondrial complex II and IV in the hippocampus of the non-deprived rats; the succinate dehydrogenase was increased in the hippocampus of non-deprived rats treated with tianeptine. So, tianeptine showed antidepressant effects conducted on maternally deprived rats, and this can be attributed to its action on the neurochemical pathways related to depression.

Imipramine reverses alterations in cytokines and BDNF levels induced by maternal deprivation in adult rats

A growing body of evidence is pointing toward an association between immune molecules, as well brain-derived neurotrophic factor (BDNF) and the depression. The present study was aimed to evaluate the behavioral and molecular effects of the antidepressant imipramine in maternally deprived adult rats. To this aim, maternally deprived and non-deprived (control group) male rats were treated with imipramine (30mg/kg) once a day for 14 days during their adult phase. Their behavior was then assessed using the forced swimming test. In addition to this, IL-10, TNF-α and IL-1β cytokines were assessed in the serum and cerebrospinal fluid (CSF). In addition, BDNF protein levels were assessed in the prefrontal cortex, hippocampus and amygdala. In deprived rats treated with saline was observed an increase on immobility time, compared with non-deprived rats treated with imipramine (p<0.05). Deprived rats treated with saline presented a decrease on BDNF levels in the amygdala (p<0.05), compared with all other groups. The IL-10 levels were decreased in the serum (p<0.05). TNF-α and IL-1β levels were increased in the serum and CSF of deprived rats treated with saline (p<0.05). Interestingly, imipramine treatment reversed the effects of maternal deprivation on BDNF and cytokines levels (p<0.05). Finally, these findings further support a relationship between immune activation, neurotrophins and the depression, and considering the action of imipramine, it is suggested that classic antidepressants could exert their effects by modulating the immune system.

Increased prevalence of mood disorders and suicidal ideation in type 2 diabetic patients

This study evaluated the association of mood disorders, suicidal ideation and the quality of life in patients with type 2 diabetes. We used a case-control study employing 996 patients suffering with type 2 diabetes (using insulin for over 1 year), and 2.145 individuals without diabetes. The groups were then used to evaluate the presence of different mood disorders and suicidal ideation, beyond quality of life. In addition to this, fasting glucose and glycosylated hemoglobin (Hb1C) were also evaluated. The data were analyzed using the Pearson chi-squared test, logistic regression, ANCOVA and Student's t-tests. We showed an association between type 2 diabetes and depressive episodes (adjusted OR = 1.8, CI 95 % 1.7-2.0, p < 0.001), recurrent depressive episodes (adjusted OR = 2.4, CI 95 % 2.2-2.6, p < 0.001), dysthymia (adjusted OR = 5.2, CI 95 % 4.9-5.5, p < 0.001), mood disorder with psychotic symptoms (adjusted OR = 2.5, CI 95 % 1.5-3.4, p < 0.001) and suicidal ideation (adjusted OR = 3.6, CI 95 % 2.5-4.8, p < 0.001, light; adjusted OR = 4.6, CI 95 % 1.5-7.7, p < 0.01, moderate and severe). The recurrent depression (OR = 1.3, CI 95 % 1.1-1.7, p < 0.05) and psychotic symptoms (OR = 4.1, CI 95 % 1.1-15.1, p < 0.05) were associated with higher levels of Hb1C. Dysthymia was associated with high blood glucose (OR = 1.6, CI 95 % 1.1-2.5, p < 0.05). Patients had lower mean scores in the following domains: physical [36.5 (13.6) × 56.0 (4.9), p < 0.001)], psychological [42.6 (8.6) × 47.9 (8.6), p < 0.001] and environmental [40.0 (8.6) × 49.3 (8.3), p < 0.001], but had higher scores in the area of social relations [50.2 (16.9) × 35.7 (27.9), p < 0.001]. The data demonstrated a worse quality of life, a high comorbidity of type 2 DM with depressive disorders and suicidal ideation. In addition, the poor control of DM is associated with the severity of mood disorders.