Potential antidepressant-like effect of piperazine derivative LQFM212 in mice: Role of monoaminergic pathway and brain-derived neurotrophic factor.

Major depression disorder (MDD) is one of the most widespread and debilitating psychiatric diseases and may be associated with other mental disorders such as anxiety. Despite advances in neurobiology studies, currently no established mechanism can explain all facets of MDD, and available drugs often show therapeutic delay for clinical effectiveness and response rates in patients are around 50 %. Previous activities of piperazine derivatives on CNS are indicators of its therapeutic potential for treating mental disorders. In this regard, we have previously shown that the piperazine derivative 2,6-di-tert-butyl-4-((4-(2-hydroxyethyl)piperazin-1-yl)methyl)phenol (LQFM212) has anxiolytic-like activity which involves serotonergic pathway, nicotinic receptors and BZD-site of GABAA receptor, without cognitive impairments. Herein, was evaluated the potential antidepressant-like effect of LQFM212 on forced swimming test (FST) after a single dose of 54 µmol/kg and after repeated treatment for 15 days in mice. Pretreatment with WAY-100635, PCPA, prazosin, SCH-23390, sulpiride or AMPT reversed the antidepressant-like effect on FST, suggesting that monoaminergic pathway contributes for effects of LQFM212. Furthermore, repeated treatment with LQFM212 increased hippocampal BDNF levels dosed by ELISA kit. In assessment of possible adverse effects, repeated treatment with LQFM212 did not alter the body weight of the animals, glutathione levels in the liver, and serum levels of AST, ALT, urea, and creatinine. Taken together, the results showed that LQFM212 has an antidepressant-like effect that involves monoaminergic pathway and increased BDNF levels. This compound represents promising candidate for prototype of psychoactive drugs for treatment of anxiety and depression disorders since these pathological conditions may exist in comorbidities.

Methyl jasmonate reverses chronic stress-induced memory dysfunctions through modulation of monoaminergic neurotransmission, antioxidant defense system, and Nrf2 expressions.

Unpredictable chronic mild stress (UCMS) has been shown to cause memory loss via increased oxidative stress and deregulation of monoaminergic and cholinergic neurotransmissions. Although the benefits of methyl jasmonate (MJ), a well-known anti-stress plant hormone against chronic stress-induced psychopathologies, have been earlier reported, its effects on antioxidant defense molecules, monoaminergic transmitters, and nuclear factor erythroid 2-related factor 2 (Nrf2) immunopositive cells have not been extensively studied. The present study was designed to examine its effect on memory functions, antioxidant biomarkers, monoaminergic transmitters, and Nrf2 immunopositive cell expression in rats exposed to UCMS. Rats received an intraperitoneal injection of MJ (10, 25, and 50 mg/kg) 30 min before exposure to UCMS daily for 28 days. Memory function was assessed on day 29 using a modified elevated plus maze and novel object recognition tests. The antioxidant biomarkers, level of monoamines (serotonin, noradrenaline, and dopamine), and Nrf2 immunopositive cell expression were determined in the rat brain tissues. The activity of cholinesterase and monoamine oxidase enzymes was also determined. MJ attenuated memory deficits and elevated the brain levels of monoamines in UCMS rats. UCMS-induced increase of brain cholinesterase and monoamine oxidase activities was inhibited by MJ. Also, MJ attenuated UCMS-induced decrease in antioxidant enzymes (CAT, GPx, GST, and SOD) and thiol contents in the brains of rats. UCMS-induced increase in NO level and Nrf2 immunopositive cell expression in the rat's brain was attenuated by MJ. Taken together, these findings suggest that increasing antioxidant defense molecules and monoaminergic/cholinergic neurotransmitters and decreasing the Nrf2 immunopositive cell expressions may contribute to the memory-promoting effects of MJ in rats exposed to UCMS.

Carnosine and L-arginine attenuate the downregulation of brain monoamines and gamma aminobutyric acid; reverse apoptosis and upregulate the expression of angiogenic factors in a model of hemic hypoxia in rats.

PURPOSE: The purpose of the present study was to investigate the preventive effect of L-arginine (ARG) and carnosine (CAR) on hypoxia-induced neurotoxicity in rats. The impact on neuro-inflammation, apoptosis, angiogenesis, and the brain levels of monoamines and GABA were investigated. METHODS: Rats were divided into the following: normal control, hypoxia model induced by sodium nitrite (75 mg/kg s.c), and hypoxic rats pre-treated with CAR (250 mg/kg), ARG (200 mg/kg), and their combination. RESULTS: Data revealed that hypoxia induced significant elevation of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and its receptor reflecting the stimulation of angiogenesis. Hypoxia also resulted in increased inflammatory mediators-including nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). In addition, hypoxia initiates cerebral apoptosis as revealed by increased caspase-3 and BAX with reduced Bcl-2. These changes were associated with reduced brain levels of GABA and monoamines including noradrenaline (NADR), dopamine (DOP), and serotonin (SER). Pre-treatment with ARG and/or CAR significantly mitigated the neural changes induced by hypoxia and attenuated the elevated levels of NF-κB, TNF-α, IL-6, caspase-3, and BAX, while ameliorated the reduced levels of Bcl-2, NADR, DOP, SER, and GABA, with the best improvement observed with the combination. Further elevation of the angiogenic markers was observed indicating their role in boosting oxygen delivery to brain. CONCLUSION: CAR, ARG, and, importantly, their combination could effectively protect against hypoxia-induced neurotoxicity, via their angiogenic, anti-inflammatory, and anti-apoptotic properties in addition to reversing the effect on GABA and monoamines.

Neurochemical impact of the 5-HT2C receptor agonist WAY-163909 on monoamine tissue content in the rat brain.

Serotonin2C receptor (5-HT2C) agonists are promising drugs for the treatment of neuropsychiatric diseases. However, their effect is not completely understood in part because they possibly affect several neurobiological networks simultaneously. We studied the effect of the 5-HT2C receptor agonist WAY-163909 (0.3 and 3 mg/kg; i.p.) on the tissue concentration of dopamine (DA), 5-HT and noradrenaline (NA) in 29 rat brain regions related to motor, cognitive, mood and vegetative networks. We found that WAY-163909, without altering the tissue concentration of NA, increased 5-HT concentrations in the medial orbitofrontal cortex and the motor cortex M2 at 3 mg/kg and decreased it in the dorsolateral orbitofrontal cortex at 0.3 mg/kg. WAY-163909 enhanced DA concentrations in the central nucleus of the amygdala at 0.3 mg/kg and reduced it in the dorsal hypothalamus at 3 mg/kg. Using correlative analysis of the tissue content of monoamines, WAY-163909 dramatically changed the profile and the pattern of the correlations within and between monoaminergic systems without drastically changing the total number of these correlations. The profile of these changes in correlations was dose-dependent as it was very different between the two doses within and among monoaminergic systems. In conclusion, the data indicated that the 5-HT2C receptor agonist WAY-163909 quantitatively alters monoamine content in very few regions but promotes multiple changes of monoaminergic connectivity in the brain.

N-acetylcysteine prevents ketamine-induced adverse effects on development, heart rate and monoaminergic neurons in zebrafish.

N-acetylcysteine, a precursor molecule of glutathione, is an antioxidant. Ketamine, a pediatric anesthetic, has been implicated in cardiotoxicity and neurotoxicity including modulation of monoaminergic systems in mammals and zebrafish. Here, we show that N-acetylcysteine prevents ketamine's adverse effects on development and monoaminergic neurons in zebrafish embryos. The effects of ketamine and N-acetylcysteine alone or in combination were measured on the heart rate, body length, brain serotonergic neurons and tyrosine hydroxylase-immunoreactive (TH-IR) neurons. In the absence of N-acetylcysteine, a concentration of ketamine that produces an internal embryo exposure level comparable to human anesthetic plasma concentrations significantly reduced heart rate and body length and those effects were prevented by N-acetylcysteine co-treatment. Ketamine also reduced the areas occupied by serotonergic neurons in the brain, whereas N-acetylcysteine co-exposure counteracted this effect. TH-IR neurons in the embryo brain and TH-IR cells in the trunk were significantly reduced with ketamine treatment, but not in the presence of N-acetylcysteine. In our continued search for compounds that can prevent ketamine toxicity, this study using specific endpoints of developmental toxicity, cardiotoxicity and neurotoxicity, demonstrates protective effects of N-acetylcysteine against ketamine's adverse effects. This is the first study that shows the protective effects of N-acetylcysteine on ketamine-induced developmental defects of monoaminergic neurons as observed in a whole organism.

Mesilato de rasagilina em combinação com levodopa para o tratamento de pacientes com doença de Parkinson com complicações motoras / Rasagiline mesylate in combination with levodopa for the treatment of patients with Parkinson's disease with motor complications

CONTEXTO: a doença de Parkinson (DP) tem distribuição universal e atinge a todos os grupos étnicos e classes socioeconômicas, com uma discreta predominância no sexo masculino. É a segunda desordem neurodegenerativa mais frequente, estando atrás apenas da doença de Alzheimer (1). A prevalência em países industrializados é estimada ao redor de 0,3% para toda a população, chegando a cerca de 1 a 4% na população acima de 65 anos. A incidência varia entre 8 a 18 casos por 100.000 pessoas-ano. No Brasil, um estudo de base populacional identificou prevalência de 3,3% para a DP entre maiores de 60 anos (2). Embora a idade seja o principal fator de risco para a doença, com claro aumento da prevalência e da incidência com o envelhecimento da população, há casos em pacientes jovens, principalmente formas monogênicas, que ocorrem em cerca de 10% do total de casos (1). É um doença crônica e progressiva, caracterizada por sintomas motores e não-motores, que provoca incapacidade funcional e aumento da mortalidade. O tratamento da DP consiste no uso de medicamentos que proporcionam estímulo dopaminérgico, principalmente a levodopa, o que possibilita um controle quase ótimo dos sintomas motores nos primeiros anos de uso. Entretanto, em aproximadamente cinco anos, cerca de metade dos pacientes apresentarão complicações motoras induzidas pelo uso crônico desta medicação, o que determina piora da qualidade de vida. As principais complicações são a flutuação da resposta motora (perda do efeito terapêutico antes do esperado e/ou de forma súbita) e discinesia (movimentos involuntários hipercinéticos). De acordo com o PCDT de 2010 para DP(3), o manejo da flutuação motora induzida por levodopa é feito com a associação de agonistas dopaminérgicos (bromocriptina ou pramipexol) e/ou inibidores da COMT (entocapona e tolcapona). Dados do DATASUS mostram que no ano de 2015 cerca de 50 mil pessoas faziam uso dessas medicações no Brasil. TECNOLOGIA: Mesilato de rasagilina (AZILECT®). INDICAÇÃO: pacientes com doença de Parkinson em uso de levodopa com complicações motoras. PERGUNTA: O uso de mesilato de rasagilina como terapia adjuvante à levodopa é eficaz e segura no tratamento de pacientes com DP com complicações motoras quando comparado ao uso de agonistas dopaminérgicos e inibidores da COMT disponíveis no SUS? EVIDÊNCIAS CIENTÍFICAS: o principal estudo apresentado pelo demandante é uma revisão sistemática com meta-análise de 44 ensaios clínicos para avaliar os tratamentos disponíveis para doença de Parkinson em uso de levodopa com complicação motora. Três estudos avaliaram a tecnologia proposta pelo demandante, um com comparador ativo (entacapona) e os outros comparados contra placebo. Como resultado, o mesilato de rasagilina 1mg uma vez ao dia foi eficaz no controle das complicações motoras de pacientes com DP em uso de levodopa. As medidas de eficácia mais importantes foram redução do tempo de off e da dose de levodopa e melhora da escala UPDRS. Em comparações indiretas, os agonistas dopaminérgicos foram melhores do que os inibidores da COMT e os inibidores da MAOB (incluindo rasagilina). Esses dois últimos foram semelhantes entre si. Em relação à segurança, os inibidores da MAOB apresentaram menos efeitos adversos em comparação com as outras duas classes, especialmente no que se refere ao surgimento da discinesia induzida por levodopa. As principais limitações deste estudo foram o (1) potencial viés de publicação, que não foi adequadamente avaliado, (2) as comparações, em sua maioria, indiretas e (3) a heterogeneidade entre os estudos. AVALIAÇÃO ECONÔMICA: utilizou-se um modelo de custo-minimização, considerando a população definida na pergunta PICO e um horizonte temporal de um ano, pela perspectiva do SUS. Os comparadores foram as alternativas atualmente disponíveis no SUS e o desfecho foi o custo anual. O uso da rasagilina representou uma redução de custo entre 57% a 78% entre os anos de 2017 a 2021, a depender do comparador escolhido. Esse resultado manteve-se favorável à nova tecnologia após análise de sensibilidade. A principal limitação é que foi um modelo de custo-minimização quando a maioria das comparações entre as drogas foi indireta. O mais adequado seria um modelo pleno de custo-efetividade. AVALIAÇÃO DE IMPACTO ORÇAMENTÁRIO: A população elegível para o estudo de impacto orçamentário considerou estimativas baseadas em dados extraídos do DATASUS do número de pacientes com DP em uso de qualquer um dos medicamentos comparadores. Os custos anuais de cada tratamento foram obtidas na análise econômica. Como resultado, considerando um período de cinco anos (2017-2021), projetou-se uma economia de R$ 184,45 milhões de recursos do SUS.(AU)

¿En qué consiste el efecto procognitivo de los antidepresivos? / What is the pro-cognitive effect of antidepressants?

La disfunción cognitiva en el trastorno depresivo mayor (TDM) abarca varios dominios incluyendo, pero no limitados, a la función ejecutiva, la memoria verbal y la atención. Por otra parte, la disfunción cognitiva es una manifestación residual frecuente en la depresión y puede persistir durante la fase de remisión de los síntomas afectivos y somáticos. Los déficits cognitivos también pueden impedir la recuperación funcional incluyendo la capacidad de recuperación laboral, social y familar. Los nuevos antidepresivos como vortioxetina parecen conseguir una importante mejoría en dominios cognitivos alterados en el TDM y superan el efecto antidepresivo a este nivel de los antidepresivos convencionales y los antidepresivos selectivos. Los objetivos generales de este artículo de opinión son evaluar críticamente los efectos de los antidepresivos disponibles, así como las nuevas dianas terapéuticas sobre la disfunción neurocognitiva en el TDM (AU)

Cognitive dysfunction in major depressive disorder (MDD) spans multiple domains, including-but not limited to-executive function, verbal memory and attention. Moreover, cognitive dysfunction is a common residual manifestation in depression and may persist during the remission phase of affective and somatic symptoms. Cognitive deficits can also prevent functional recovery, including the ability to work, and social and familar recovery. New antidepressants such as Vortioxetine seem to achieve a significant improvement in the cognitive domains that are altered in MDD, thus providing additional benefits over conventional and selective antidepressants. The general objectives of this article are to critically assess the effects of available antidepressants and to discuss new therapeutic targets on neurocognitive dysfunction in MDD (AU)

Antidepressant-like Potentials of Buchholzia Coriacea Seed Extract: Involvement of Monoaminergic and Cholinergic Systems, and Neuronal Density in the Hippocampus of Adult Mice.

Buchholzia coriacea, taken by elderly, has phytochemicals that have neuro-active metabolites, and the folkloredocumented its use in neuro-behavioral despairs. Previous study in our laboratory shows that methanol extracts of Buchholziacoriacea (MEBC) seeds possess antidepressant-like potentials in laboratory rodents. This present study was conducted toinvestigate the probable mechanism(s) of action by which MEBC potentiates its effects using laboratory rodents.Involvements of serotonergic, cholinergic and adrenergic systems were studied using Forced Swimming Test (FST) and TailSuspension Test (TST) models of behavioral despair. Antagonists which including: Prazosin, an alpha-1-adrenergic receptorblocker (62.5 µg/kg, i.p.), metergoline, a 5HT2 receptor blocker (4 mg/kg, i.p.) and atropine, a -muscarinic cholinergicreceptor blocker (1mg/kg i.p.) were administered before effective dose of MEBC (50mg/kg). Also, the hippocampi of theanimals were studied for changes in neuronal density using Nissl Staining. Our findings showed that mobility was reversedin animals pre-treated with atropine, prazosin, and metergoline significantly (P˂0.05), showing a possible involvement ofthe corresponding systems. However, there was a significant reduction in immobility time (P<0.001) during FST afterchronic administration of the MEBC. The hippocampus showed no significant changes (P<0.05) in neuronal density. Inconclusion, MEBC probably potentiates its antidepressant-like potentials via the cholinergic, adrenergic and partly byserotonergic systems.

Beyond Monoamines-Novel Targets for Treatment-Resistant Depression: A Comprehensive Review.

Major depressive disorder (MDD) is a leading cause of disability worldwide. Current first line therapies target modulation of the monoamine system. A large variety of agents are currently available that effectively alter monoamine levels; however, approximately one third of MDD patients remain treatment refractory after adequate trials of multiple monoamine based therapies. Therefore, patients with treatment-resistant depression (TRD) may require modulation of pathways outside of the classic monoamine system. The purpose of this review was thus to discuss novel targets for TRD, to describe their potential mechanisms of action, the available clinical evidence for these targets, the limitations of available evidence as well as future research directions. Several alternate pathways involved in the patho-etiology of TRD have been uncovered including the following: inflammatory pathways, the oxidative stress pathway, the hypothalamic-pituitary-adrenal (HPA) axis, the metabolic and bioenergetics system, neurotrophic pathways, the glutamate system, the opioid system and the cholinergic system. For each of these systems, several targets have been assessed in preclinical and clinical models. Preclinical models strongly implicate these pathways in the patho-etiology of MDD. Clinical trials for TRD have been conducted for several novel targets; however, most of the trials discussed are small and several are uncontrolled. Therefore, further clinical trials are required to assess the true efficacy of these targets for TRD. As well, several promising novel agents have been clinically tested in MDD populations, but have yet to be assessed specifically for TRD. Thus, their applicability to TRD remains unknown.

Diffuse noxious inhibitory controls and nerve injury: restoring an imbalance between descending monoamine inhibitions and facilitations.

Diffuse noxious inhibitory controls (DNICs) utilize descending inhibitory controls through poorly understood brain stem pathways. The human counterpart, conditioned pain modulation, is reduced in patients with neuropathy aligned with animal data showing a loss of descending inhibitory noradrenaline controls together with a gain of 5-HT3 receptor-mediated facilitations after neuropathy. We investigated the pharmacological basis of DNIC and whether it can be restored after neuropathy. Deep dorsal horn neurons were activated by von Frey filaments applied to the hind paw, and DNIC was induced by a pinch applied to the ear in isoflurane-anaesthetized animals. Spinal nerve ligation was the model of neuropathy. Diffuse noxious inhibitory control was present in control rats but abolished after neuropathy. α2 adrenoceptor mechanisms underlie DNIC because the antagonists, yohimbine and atipamezole, markedly attenuated this descending inhibition. We restored DNIC in spinal nerve ligated animals by blocking 5-HT3 descending facilitations with the antagonist ondansetron or by enhancing norepinephrine modulation through the use of reboxetine (a norepinephrine reuptake inhibitor, NRI) or tapentadol (µ-opioid receptor agonist and NRI). Additionally, ondansetron enhanced DNIC in normal animals. Diffuse noxious inhibitory controls are reduced after peripheral nerve injury illustrating the central impact of neuropathy, leading to an imbalance in descending excitations and inhibitions. Underlying noradrenergic mechanisms explain the relationship between conditioned pain modulation and the use of tapentadol and duloxetine (a serotonin, NRI) in patients. We suggest that pharmacological strategies through manipulation of the monoamine system could be used to enhance DNIC in patients by blocking descending facilitations with ondansetron or enhancing norepinephrine inhibitions, so possibly reducing chronic pain.

Tesofensine, a novel triple monoamine re-uptake inhibitor with anti-obesity effects: dopamine transporter occupancy as measured by PET.

Tesofensine (TE) is a novel triple monoamine re-uptake inhibitor inducing a potent inhibition of the re-uptake process in the synaptic cleft of the neurotransmitters dopamine, norepinephrine, and serotonin. In recent preclinical and clinical evaluations TE showed a robust anti-obesity effect, but the specific mechanism of this triple monoamine re-uptake inhibitor still needs to be further elucidated. This positron emission tomography (PET) study, using [¹¹C]ßCIT-FE, aimed to assess the degree of the dopamine transporter (DAT) occupancy, at constant TE plasma levels, following different oral, multiple doses of TE during totally 8-12 days. In addition, the relationships between DAT occupancy and TE plasma concentrations, or doses, were investigated to enable assessment of DAT occupancies in subsequent clinical trials. The results demonstrated that TE induced a dose-dependent blockade of DAT following multiple doses of 0.125-1 mg TE at anticipated steady-state conditions. The mean striatal DAT occupancy varied dose-dependently between 18% and 77%. A sigmoid E(max) model well described the relationship between striatal DAT occupancy and TE plasma concentrations or doses. It was estimated that the maximum achievable DAT occupancy was about 80% and that half of this effect was accomplished by approximately 0.25 mg TE and a plasma drug concentration of 4 ng/ml. The results indicated an important mechanism of action of TE on DAT. Further, these results suggest that the previously reported dose-dependent weight loss, in TE treated subjects, was in part mediated by an up-regulation of dopaminergic pathways due to enhanced amounts of synaptic dopamine after blockade of DAT.

Increased brain monoaminergic tone after the NMDA receptor GluN2A subunit gene knockout is responsible for resistance to the hypnotic effect of nitrous oxide.

N-methyl-d-aspartate (NMDA) receptors can be inhibited by inhalational anesthetics in vitro at clinically relevant concentrations. Here, to clarify the role of NMDA receptors in anesthetic-induced unconsciousness, we examined the hypnotic properties of isoflurane, sevoflurane and nitrous oxide in NMDA receptor GluN2A subunit knockout mice. The hypnotic properties of inhalational anesthetics were evaluated in mice in the loss of righting reflex (LORR) assay by measuring the 50% concentration for LORR (LORR ED(50)). Knockout mice displayed isoflurane and sevoflurane LORR ED(50) values similar to wild-type controls, indicating no significant contribution of these receptors to the hypnotic action of halogenated anesthetics. However, compared with wild-type controls, mutant mice displayed larger isoflurane LORR ED(50) values in the presence of nitrous oxide, indicating a resistance to this gaseous anesthetic. Knockout mice have enhanced brain monoaminergic activity which occurs secondary to NMDA receptor dysfunction, and the observed resistance to the isoflurane LORR ED(50)-sparing effect of nitrous oxide could be abolished by pretreatment with the dopamine D(2) receptor antagonist droperidol or with the serotonin 5-HT(2A) receptor antagonist ketanserin. Thus, resistance to nitrous oxide in knockout mice appears to be a secondary phenomenon of monoaminergic origin and not a direct result of impaired NMDA receptor function. Our results indicate that NMDA receptors are not critically involved in the hypnotic action of conventionally-used inhalational anesthetics. Also, they suggest that increased brain monoaminergic tone can diminish the effects of general anesthesia. Finally, they provide further evidence that changes secondary to genetic manipulation can explain the results obtained in global knockouts.

Fructus Aurantii induced antidepressant effect via its monoaminergic mechanism and prokinetic action in rat.

Depression could hardly get a satisfactory effect from the currently available antidepressants. To get a more effective treatment, antidepressant effect and monoaminergic mechanism of Fructus Aurantii (FRA) in the rat forced swimming test (FST) and open field test (OFT), and its prokinetics were examined. FST and OFT were respectively used to evaluate the antidepressant effect and locomotor activity of FRA. We observed the effects of monoamine receptor antagonists on FRA-induced antidepressant effect in rat. The effects of FRA on intestinal transit, gastric emptying and in vitro jejunum contractile activity were assessed. FRA decreased significantly the immobility time (32.6±8.5, 30.3±5.2 vs 56.4±9.4, all p<0.01) in FST, dose-dependent increased the locomotor activity (102±17.5, 120±18.5 vs 89±9.8, p<0.05 or 0.01), significantly accelerated gastric emptying (GE: 48.1±6.3, 39.5±5.7 vs 19.5±3.8, p<0.01) and intestinal transit (IT: 67.3±9.1, 64.2±6.3 vs 49.1±8.2, p<0.01) of the semi-liquid meal, compared with vehicle. And FRA (1 µM, 10 µM) significantly increased the mean amplitude (0.24±0.021 and 0.281±0.015) of contraction in jejunum of rat compared with vehicle (0.149±0.011) in vitro. FRA (10 µM) could induce a largest amplitude (0.281±0.015) of contraction in jejunum. The anti-immobility effect of FRA in FST was prevented by pre-treatment of rat with p-chlorophenylalanine methyl ester, WAY100635, ketanserin, haloperidol, SCH233390, sulpiride, yohimbine, but not prazosin. FRA could simultaneously induce prokinetics and antidepressant effect, deserves further to investigate.

Triple reuptake inhibitors for treating subtypes of major depressive disorder: the monoamine hypothesis revisited.

INTRODUCTION: Major depression is one of the most prevalent forms of mental illnesses and is among the leading causes of disability, affecting about 121 million people worldwide. Approximately 30% of patients fail to respond to present therapies. Therefore, the search for novel antidepressant drugs continues. AREAS COVERED: The most prescribed antidepressants are serotonin reuptake inhibitors and/or noradrenaline reuptake inhibitors, which only indirectly affect dopaminergic neurotransmission. As a consequence, residual symptoms remain, including impaired motivation and impaired pleasure. This article reviews the development of new broad-spectrum antidepressants, the triple reuptake inhibitors, which also increase brain dopamine levels. EXPERT OPINION: In this review, a distinction is made between the subtypes of melancholic and atypical depressions and their associated brain abnormalities and dysfunctions in neurotransmitter systems. Subsequently, we propose a hypothetical model: 'the monoamine hypothesis revisited' to predict what kind of pharmacological treatment will be effective in the different subtypes of depression. It is expected that the triple reuptake inhibitors, inhibiting the reuptake of all three monoamines, can produce a greater efficacy than traditional antidepressants especially in atypical depression. Since triple reuptake inhibitors may also dampen states of hyperglutamatergic activity and subsequent excitotoxicity, it is suggested that these new drugs have a considerable neuroprotective potential in major depression, especially in melancholic depression.

Metabolite profiling of antidepressant drug action reveals novel drug targets beyond monoamine elevation.

Currently used antidepressants elevate monoamine levels in the synaptic cleft. There is good reason to assume that this is not the only source for antidepressant therapeutic activities and that secondary downstream effects may be relevant for alleviating symptoms of depression. We attempted to elucidate affected biochemical pathways downstream of monoamine reuptake inhibition by interrogating metabolomic profiles in DBA/2Ola mice after chronic paroxetine treatment. Metabolomic changes were investigated using gas chromatography-mass spectrometry profiling and group differences were analyzed by univariate and multivariate statistics. Pathways affected by antidepressant treatment were related to energy metabolism, amino acid metabolism and hormone signaling. The identified pathways reveal further antidepressant therapeutic action and represent targets for drug development efforts. A comparison of the central nervous system with blood plasma metabolite alterations identified GABA, galactose-6-phosphate and leucine as biomarker candidates for assessment of antidepressant treatment effects in the periphery.

Antidepressant-like effect of scopoletin, a coumarin isolated from Polygala sabulosa (Polygalaceae) in mice: evidence for the involvement of monoaminergic systems.

The relationship between depression and monoaminergic systems has been hypothesized for many years. In this study, we have investigated the possible antidepressant-like effect of scopoletin, a coumarin from Polygala sabulosa in the tail suspension test and forced swimming test. Moreover, the ability of scopoletin to reverse the depression-like behavior in the forced swimming test induced by immobility stress in mice was evaluated. Scopoletin reduced the immobility time in the tail suspension test (10-100mg/kg, p.o.), but not in the forced swimming test. Fluoxetine (positive control) decreased the immobility time in the forced swimming and tail suspension tests (20mg/kg, p.o. and 10mg/kg. p.o., respectively). Immobility stress caused an increase in the immobility time in the forced swimming test (depression-like behavior), which was reversed by scopoletin (1-100mg/kg, p.o.) and fluoxetine (10mg/kg, p.o.). Scopoletin produced no psychostimulant effect in the open-field test. The pretreatment of mice with ketanserin (5mg/kg, i.p., a preferential 5-HT(2A) receptor antagonist), prazosin (1mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), haloperidol (0.2mg/kg, i.p., a dopaminergic receptor antagonist), SCH23390 (0.05 mg/kg, s.c., a dopamine D(1) receptor antagonist) or sulpiride (50mg/kg, i.p., a dopamine D(2) receptor antagonist), but not WAY100635 (0.1mg/kg, s.c., a selective 5-HT(1A) receptor antagonist) prevented the antidepressant-like effect of scopoletin (10mg/kg, p.o.) in the tail suspension test. The results indicate that its antidepressant-like effect is dependent on the serotonergic (5-HT(2A) receptors), noradrenergic (alpha(1)- and alpha(2)-adrenoceptors) and dopaminergic (dopamine D(1) and D(2) receptors) systems.

Subjective and objective effects of the novel triple reuptake inhibitor tesofensine in recreational stimulant users.

Tesofensine is a (triple) reuptake inhibitor of noradrenaline, dopamine, and serotonin that is in development for the treatment of obesity. The abuse potential of triple reuptake inhibitors is not yet known, and so this study was undertaken to evaluate the potential abuse-related effects of tesofensine in humans. It was designed as a single-dose, randomized, double-blind, crossover study involving tesofensine vs. placebo, D-amphetamine (positive control for dopaminergic/stimulant effects), bupropion, and atomoxetine (negative/unscheduled controls) in recreational stimulant users (N = 52). Subjective and objective measures were assessed for 48 h after drug administration. The study results show that the effects of D-amphetamine were significantly greater than those of placebo on all primary and secondary subjective measures. The effects of tesofensine were not significantly different from those of placebo and were lower than those of D-amphetamine 30 mg on all primary and most secondary measures. The effects of tesofensine were either lower than or not different from those of bupropion or atomoxetine. These results demonstrate that the abuse potential for tesofensine is no greater than that of bupropion or atomoxetine, and tesofensine is therefore unlikely to be recreationally abused.

[Neurochemical study of effects of the new anxiolytic drugs afobazol and ladasten on the synthesis and metabolism of monoamines and their metabolites in the brain structures of Wistar rat on the model of monoamine synthesis blockade induced by aromatic amino acid decarboxylase inhibitor NSD-1015].

Results of a neurochemical study of the effects of the new anxiolytic drugs afobazole and ladasten on the synthesis and metabolism of monoamines and their metabolites determined by HPLC on the model of monoamine synthesis blockade induced by NSD-1015 (aromatic L-amino acid decarboxylase) in the brain structures of Wistar rats are reported. A decrease in the levels of DOPAC in hypothalamus and HVA in striatum after afobazole injection may be evidence of an inhibitory action of this drug on the activity of monoamine oxidase (MAO-A), which is the main enzyme involved in dopamine biodegradation. Afobazole was also found to increase the content of serotonin (5-HT) as well as its precursor (5-OTP) and its main metabolite (5-HIAA) in hypothalamus by up to 50, 60 and 50%, respectively, which confirms a hypothesis that this anxiolytic drug can modulate the activity of tryptophan hydroxylase (5-OTP synthesis enzyme). In contrast to afobazole, ladasten demonstrated the ability to increase the level of L-DOPA (a dopamine precursor) in virtually all functional structures of the brain (except for hippocamp), which may support the hypothesis suggestion concerning a predominant action of this drug on the activity of tyrosine hydroxylase. Ladasten exhibited selectivity with respect to the dopaminergic system and affected only parameters of the dopamine metabolism, in particular, by increasing the HVA content in nucleus accumbens and decreasing it in the hypothalamus. The drug also affected the dopamine turnover parameters, producing an increase in both HVA/dopamine ratio in nucleus accumbens and DOPAC/dopamine ratio in hippocamp.

Psychostimulant-like discriminative stimulus and locomotor sensitization properties of the wake-promoting agent modafinil in rodents.

UNLABELLED: The present studies assessed the potential abuse liability and likely mechanism(s) of action of the wake-promoting agent modafinil. METHODS: Experiments assessed the locomotor sensitization (LS) and discriminative stimulus (DS) properties of modafinil in mouse and rat, respectively. Comparative data were generated with a range of psychostimulants and monoamine reuptake inhibitors. RESULTS: Repeated administration of d-amphetamine and cocaine, psychostimulants with high abuse liability, resulted in the induction and expression of LS in mice. Bupropion and caffeine, two psychostimulants not abused in humans, were not associated with LS. GBR12909 induced LS during repeated exposure, but there was no evidence of expression of LS after acute challenge following withdrawal. In contrast, repeated administration of modafinil resulted in the expression, but not induction, of LS. d-amphetamine, but not the mu-opioid agonist morphine or the nAChR agonist nicotine, fully substituted for the cocaine DS in rats. The selective dopamine transporter (DAT) inhibitor GBR12909 fully substituted, the preferential norepinephrine transporter (NET) inhibitor desipramine partially substituted, and the selective serotonin reuptake inhibitor citalopram failed to substitute for cocaine. Modafinil fully substituted for cocaine, similar to the mixed DAT/NET inhibitor bupropion. CONCLUSIONS: Two preclinical assays indicated potential abuse liability of modafinil; drug discrimination studies suggest DAT blockade by modafinil is a likely mechanism of action in vivo.

Antidepressant stimulation of CDP-diacylglycerol synthesis does not require monoamine reuptake inhibition.

BACKGROUND: Recent studies demonstrate that diverse antidepressant agents increase the cellular production of the nucleolipid CDP-diacylglycerol and its synthetic derivative, phosphatidylinositol, in depression-relevant brain regions. Pharmacological blockade of downstream phosphatidylinositide signaling disrupted the behavioral antidepressant effects in rats. However, the nucleolipid responses were resistant to inhibition by serotonin receptor antagonists, even though antidepressant-facilitated inositol phosphate accumulation was blocked. Could the neurochemical effects be additional to the known effects of the drugs on monoamine transmitter transporters? To examine this question, we tested selected agents in serotonin-depleted brain tissues, in PC12 cells devoid of serotonin transporters, and on the enzymatic activity of brain CDP-diacylglycerol synthase - the enzyme that catalyzes the physiological synthesis of CDP-diacylglycerol. RESULTS: Imipramine, paroxetine, and maprotiline concentration-dependently increased the levels of CDP-diacylglycerol and phosphatidylinositides in PC12 cells. Rat forebrain tissues depleted of serotonin by pretreatment with p-chlorophenylalanine showed responses to imipramine or maprotiline that were comparable to respective responses from saline-injected controls. With fluoxetine, nucleolipid responses in the serotonin-depleted cortex or hippocampus were significantly reduced, but not abolished. Each drug significantly increased the enzymatic activity of CDP-diacylglycerol synthase following incubations with cortical or hippocampal brain tissues. CONCLUSION: Antidepressants probably induce the activity of CDP-diacylglycerol synthase leading to increased production of CDP-diacylglycerol and facilitation of downstream phosphatidylinositol synthesis. Phosphatidylinositol-dependent signaling cascades exert diverse salutary effects in neural cells, including facilitation of BDNF signaling and neurogenesis. Hence, the present findings should strengthen the notion that modulation of brain phosphatidylinositide signaling probably contributes to the molecular mechanism of diverse antidepressant medications.