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Brain Struct Funct ; 226(8): 2603-2616, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34363521


Ketamine has rapid and robust antidepressant effects. However, unwanted psychotomimetic effects limit its widespread use. Hence, several studies examined whether GluN2B-subunit selective NMDA antagonists would exhibit a better therapeutic profile. Although preclinical work has revealed some of the mechanisms of action of ketamine at cellular and molecular levels, the impact on brain circuitry is poorly understood. Several neuroimaging studies have examined the functional changes in the brain induced by acute administration of ketamine and Ro 25-6981 (a GluN2B-subunit selective antagonist), but the changes in the microstructure of gray and white matter have received less attention. Here, the effects of ketamine and Ro 25-6981 on gray and white matter integrity in male Sprague-Dawley rats were determined using diffusion-weighted magnetic resonance imaging (DWI). In addition, DWI-based structural brain networks were estimated and connectivity metrics were computed at the regional level. Immunohistochemical analyses were also performed to determine whether changes in myelin basic protein (MBP) and neurofilament heavy-chain protein (NF200) may underlie connectivity changes. In general, ketamine and Ro 25-6981 showed some opposite structural alterations, but both compounds coincided only in increasing the fractional anisotropy in infralimbic prefrontal cortex and dorsal raphe nucleus. These changes were associated with increments of NF200 in deep layers of the infralimbic cortex (together with increased MBP) and the dorsal raphe nucleus. Our results suggest that the synthesis of NF200 and MBP may contribute to the formation of new dendritic spines and myelination, respectively. We also suggest that the increase of fractional anisotropy of the infralimbic and dorsal raphe nucleus areas could represent a biomarker of a rapid antidepressant response.

Int J Mol Sci ; 22(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34445375


Fast and sustained antidepressant effects of ketamine identified the mammalian target of rapamycin (mTOR) signaling pathway as the main modulator of its antidepressive effects. Thus, mTOR signaling has become integral for the preclinical evaluation of novel compounds to treat depression. However, causality between mTOR and depression has yet to be determined. To address this, we knocked down mTOR expression in mice using an acute intracerebral infusion of small interfering RNAs (siRNA) in the infralimbic (IL) or prelimbic (PrL) cortices of the medial prefrontal cortex (mPFC), and evaluated depressive- and anxious-like behaviors. mTOR knockdown in IL, but not PrL, cortex produced a robust depressive-like phenotype in mice, as assessed in the forced swimming test (FST) and the tail suspension test (TST). This phenotype was associated with significant reductions of mTOR mRNA and protein levels 48 h post-infusion. In parallel, decreased brain-derived neurotrophic factor (BDNF) expression was found bilaterally in both IL and PrL cortices along with a dysregulation of serotonin (5-HT) and glutamate (Glu) release in the dorsal raphe nucleus (DRN). Overall, our results demonstrate causality between mTOR expression in the IL cortex and depressive-like behaviors, but not in anxiety.

Depressão/psicologia , Córtex Pré-Frontal/metabolismo , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Depressão/genética , Depressão/metabolismo , Modelos Animais de Doenças , Núcleo Dorsal da Rafe/metabolismo , Técnicas de Silenciamento de Genes , Ácido Glutâmico/metabolismo , Elevação dos Membros Posteriores , Masculino , Camundongos , Serotonina/metabolismo , Natação
Biochem Pharmacol ; 185: 114433, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33513342


Major Depression is a severe psychiatric condition with a still poorly understood etiology. In the last years, evidence supporting the neuroinflammatory hypothesis of depression has increased. In the current clinical scenario, in which the available treatments for depression is far from optimal, there is an urgent need to develop fast-acting drugs with fewer side effects. In this regard, recent pieces of evidence suggest that cannabidiol (CBD), the major non-psychotropic component of Cannabis sativa with anti-inflammatory properties, appears as a drug with antidepressant properties. In this work, CBD 30 mg/kg was administered systemically to mice 30 min before lipopolysaccharide (LPS; 0.83 mg/kg) administration as a neuroinflammatory model, and behavioral tests for depressive-, anhedonic- and anxious-like behavior were performed. NF-ĸB, IκBα and PPARγ levels were analyzed by western blot in nuclear and cytosolic fractions of cortical samples. IL-6 and TNFα levels were determined in plasma and prefrontal cortex using ELISA and qPCR techniques, respectively. The precursor tryptophan (TRP), and its metabolites kynurenine (KYN) and serotonin (5-HT) were measured in hippocampus and cortex by HPLC. The ratios KYN/TRP and KYN/5-HT were used to estimate indoleamine 2,3-dioxygenase (IDO) activity and the balance of both metabolic pathways, respectively. CBD reduced the immobility time in the tail suspension test and increased sucrose preference in the LPS model, without affecting locomotion and central activity in the open-field test. CBD diminished cortical NF-ĸB activation, IL-6 levels in plasma and brain, and the increased KYN/TRP and KYN/5-HT ratios in hippocampus and cortex in the LPS model. Our results demonstrate that CBD produced antidepressant-like effects in the LPS neuroinflammatory model, associated to a reduction in the kynurenine pathway activation, IL-6 levels and NF-ĸB activation. As CBD stands out as a promising antidepressant drug, more research is needed to completely understand its mechanisms of action in depression linked to inflammation.

Antidepressivos/uso terapêutico , Canabidiol/uso terapêutico , Depressão/tratamento farmacológico , Depressão/metabolismo , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/toxicidade , Animais , Antidepressivos/farmacologia , Canabidiol/farmacologia , Depressão/induzido quimicamente , Elevação dos Membros Posteriores/efeitos adversos , Elevação dos Membros Posteriores/psicologia , Mediadores da Inflamação/antagonistas & inibidores , Masculino , Camundongos
Mol Neurobiol ; 57(3): 1704-1715, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31823197


We previously reported that the inactivation (cKO) or the stabilization (cST) of ß-catenin in cells expressing the astrocyte-specific glutamate aspartate transporter (GLAST) is associated with the vulnerability or resilience to exhibit anxious/depressive-like behaviors, respectively, and to changes in hippocampal proliferation. Here, we used these cKO and cST ß-catenin mice to study the serotonergic system functionality associated with their behavioral/molecular phenotype. The activity of 5-HT1A receptors was assessed by (+)-8-OH-DPAT-induced hypothermia and [35S]GTPγS binding autoradiography. The animals' response to acute stress and the levels of extracellular serotonin (5-HT) in the medial prefrontal cortex (mPFC) were also assessed. cKO mice presented higher 5-HT1A autoreceptor functionality, lower 5-HT1A heteroreceptor functionality, and a decrease in extracellular 5-HT levels in the mPFC. These neurochemical changes were accompanied with a blunted physiological response to stress-induced hyperthermia. In contrast, cST mice showed a reduced 5-HT1A autoreceptor functionality and higher extracellular 5-HT levels in the mPFC after fluoxetine administration. Moreover, cST mice subjected to chronic corticosterone administration did not show a blunted response to fluoxetine. Our findings suggest the existence of a link between ß-catenin levels and 5-HT1A receptor functionality, which may be relevant to understand the neurobiological bases underlying the vulnerability or resilience to stress-related disorders.

Ansiedade/metabolismo , Receptor 5-HT1A de Serotonina/metabolismo , Serotonina/metabolismo , beta Catenina/metabolismo , Animais , Comportamento Animal/efeitos dos fármacos , Corticosterona/metabolismo , Depressão/metabolismo , Hipocampo/metabolismo , Masculino , Camundongos , Córtex Pré-Frontal/metabolismo
Mol Neurobiol ; 56(1): 553-566, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29737454


ß-catenin (key mediator in the Wnt signaling pathway) contributes to the pathophysiology of mood disorders, associated to neurogenesis and neuroplasticity. Decreased ß-catenin protein levels have been observed in the hippocampus and prefrontal cortex of depressed subjects. Additionally, the antidepressants exert, at least in part, their neurogenic effects by increasing ß-catenin levels in the subgranular zone of the hippocampus. To further understand the role of ß-catenin in depression and anxiety, we generated two conditional transgenic mice in which ß-catenin was either inactivated or stabilized in cells expressing CreERT under the control of the astrocyte-specific glutamate transporter (GLAST) promoter inducible by tamoxifen, which presents high expression levels on the subgranular zone of the hippocampus. Here, we show that ß-catenin inactivation in GLAST-expressing cells enhanced anxious/depressive-like responses. These behavioral changes were associated with impaired hippocampal proliferation and markers of immature neurons as doublecortin. On the other hand, ß-catenin stabilization induced an anxiolytic-like effect in the novelty suppressed feeding test and tended to ameliorate depressive-related behaviors. In these mice, the control over the Wnt/ß-catenin pathway seems to be tighter as evidenced by the lack of changes in some proliferation markers. Moreover, animals with stabilized ß-catenin showed resilience to some anxious/depressive manifestations when subjected to the corticosterone model of depression. Our findings demonstrate that ß-catenin present in GLAST-expressing cells plays a critical role in the development of anxious/depressive-like behaviors and resilience, which parallels its regulatory function on hippocampal proliferation. Further studies need to be done to clarify the importance of these changes in other brain areas also implicated in the neurobiology of anxiety and depressive disorders.

Ansiedade/metabolismo , Comportamento Animal , Depressão/metabolismo , Transportador 1 de Aminoácido Excitatório/metabolismo , Hipocampo/patologia , beta Catenina/metabolismo , Animais , Ansiedade/complicações , Comportamento Animal/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Corticosterona/administração & dosagem , Corticosterona/farmacologia , Giro Denteado/patologia , Depressão/complicações , Proteína Glial Fibrilar Ácida/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Estabilidade Proteica/efeitos dos fármacos , Fatores de Transcrição SOXB1/metabolismo
Biochem Pharmacol ; 157: 97-107, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30026022


Mental disorders have a high prevalence compared with many other health conditions and are the leading cause of disability worldwide. Several studies performed in the last years support the involvement of the endocannabinoid system in the etiopathogenesis of different mental disorders. The present review will summarize the latest information on the role of the endocannabinoid system in psychiatric disorders, specifically depression, anxiety, and schizophrenia. We will focus on the findings from human brain studies regarding alterations in endocannabinoid levels, cannabinoid receptors and endocannabinoid metabolizing enzymes in patients suffering mental disorders. Studies carried out in humans have consistently demonstrated that the endocannabinoid system is fundamental for emotional homeostasis and cognitive function. Thus, deregulation of the different elements that are part of the endocannabinoid system may contribute to the pathophysiology of several mental disorders. However, the results reported are controversial. In this sense, different alterations in gene and/or protein expression of CB1 receptors have been shown depending on the technical approach used or the brain region studied. Despite the current discrepancies regarding cannabinoid receptors changes in depression and schizophrenia, present findings point to the endocannabinoid system as a pivotal neuromodulatory pathway relevant in the pathophysiology of mental disorders.

Encéfalo/metabolismo , Endocanabinoides/metabolismo , Transtornos Mentais/metabolismo , Transtornos de Ansiedade/genética , Transtornos de Ansiedade/metabolismo , Depressão/genética , Depressão/metabolismo , Emoções , Humanos , Receptores de Canabinoides/metabolismo , Esquizofrenia/genética , Esquizofrenia/metabolismo