Flavones from Erythrina falcata are modulators of fear memory

Background: Flavonoids, which have been identified in a variety of plants, have been demonstrated to elicit beneficial effects on memory. Some studies have reported that flavonoids derived from Erythrina plants can provide such beneficial effects on memory. the aim of this study was to identify the flavonoids present in the stem bark crude extract of Erythrina falcata (CE) and to perform a bioactivity-guided study on conditioned fear memory.Methods: the secondary metabolites of CE were identified by high performance liquid chromatography combined with a diode array detector, electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI/MSn) and nuclear magnetic resonance (NMR). the buthanolic fraction (BuF) was obtained by partitioning. Subfractions from BuF (BuF1 - BuF6) and fraction flavonoidic (FfA and FfB) were obtained by flash chromatography. the BuF3 and BuF4 fractions were used for the isolation of flavonoids, which was performed using HPLC-PAD. the isolated substances were quantified by HPLC-DAD and their structures were confirmed by nuclear magnetic resonance (NMR). the activities of CE and the subfractions were monitored using a one-trial, step-down inhibitory avoidance (IA) task to identify the effects of these substances on the acquisition and extinction of conditioned fear in rats.Results: Six subclasses of flavonoids were identified for the first time in CE. According to our behavioral data, CE, BuF, BuF3 and BuF4, the flavonoidic fractions, vitexin, isovitexin and 6-C-glycoside-diosmetin improved the acquisition of fear memory. Rats treated with BuF, BuF3 and BuF4 were particularly resistant to extinction. Nevertheless, rats treated with FfA and FfB, vitexin, isovitexin and 6-C-glycoside-diosmetin exhibited gradual reduction in conditioned fear response during the extinction retest session, which was measured at 48 to 480 h after conditioning.Conclusions: Our results demonstrate that vitexin, isovitexin and diosmetin-6-C-glucoside and flavonoidic fractions resulted in a significant retention of fear memory but did not prevent the extinction of fear memory. These results further substantiate that the treatment with pure flavonoids or flavanoid-rich fractions might represent potential therapeutic approaches for the treatment of neurocognitive disorders, improvement of memory acquisition and spontaneous recovery of fear.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Brazilian Agricultural Research Corporation (EMBRAPA)Universidade Federal de São Paulo, Dept Biol Sci, Behav Pharmacol & Ethnopharmacol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, Genet Bases Thyroid Tumor Lab, Div Genet, São Paulo, BrazilBrazilian Agr Res Corp EMBRAPA, Dept Forestry Colombo, Londrina, Parana, BrazilUNESP, State Univ São Paulo, Inst Chem, Nuclei Bioassay Biosynth & Ecophysiol Nat Prod Nu, Araraquara, SP, BrazilUniversidade Federal de São Paulo, Dept Biol Sci, Behav Pharmacol & Ethnopharmacol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, Genet Bases Thyroid Tumor Lab, Div Genet, São Paulo, BrazilFAPESP: 2009/15229-8Web of Scienc

Ginkgo biloba Extract (GbE) Stimulates the Hypothalamic Serotonergic System and Attenuates Obesity in Ovariectomized Rats

Menopause is associated with increased risk to develop obesity but the mechanisms involved are not fully understood. We have shown that Ginkgo biloba extract (GbE) improved diet-induced obesity. Since GbE might be effective in the treatment of obesity related to menopause, avoiding the side effects of hormone replacement therapy, we investigated the effect of GbE on hypothalamic systems controlling energy homeostasis. Wistar rats were either ovariectomized (OVX) or Sham-operated. After 2 months, either 500 mg.kg(-1) of GbE or vehicle were administered daily by gavage for 14 days. A subset of animals received an intracerebroventricular (i.c.v.) injection of serotonin (300 mu g) or vehicle and food intake was measured after 12 and 24 h. Another subset was submitted to in vivo microdialysis and 5-HT levels of the medial hypothalamus were measured by high performance liquid chromatography, before and up to 2 h after the administration of 500 mg.kg(-1) of GbE. Additional animals were used for quantification of 5-HT1A, 5-HT1B, 5-HT2C, 5-HTT, and pro-opiomelanocortin hypothalamic protein levels by Western blotting. OVX increased food intake and body weight and adiposity while GbE attenuated these alterations. i.c.v. serotonin significantly reduced food intake in Sham, Sham + GbE, and OVX + GbE groups while it failed to do so in the OVX group. In the OVX rats, GbE stimulated 5-HT microdialysate levels while it reduced hypothalamic 5-HTT protein levels. The results indicate that GbE improved the ovariectomy-induced resistance to serotonin hypophagia, at least in part through stimulation of the hypothalamic serotonergic activity. Since body weight gain is one of the most important consequences of menopause, the stimulation of the serotonergic transmission by GbE may represent a potential alternative therapy for menopause-related obesity.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Univ Fed Sao Paulo, Dept Fisiol, Disciplina Fisiol Nutr, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Ciencias Biol, Setor Morfofisiol & Patol, Diadema, BrazilUniv Fed Sao Paulo, Dept Fisiol, Disciplina Fisiol Nutr, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Ciencias Biol, Setor Morfofisiol & Patol, Diadema, BrazilCNPq: 453924/2014-0FAPESP: 2012/03172-4FAPESP: 2014/18435-6Web of Scienc

Neural plasticity: relations with behavior and experimental approaches

Behavioral adaptiveness to different situations as well as behavioral individuality result from the interrelations between environmental sitmuli and the responses of an organism.These kind of interrelationships also shape the neural circuits as well as characterize the plasticity and the neural individuality of the organism. Studies on neural plasticity may analyze changes in neural circuitry after environmental manipulations or changes in behavior after lesions in the nervous system. Issues on neural plasticity and recovery of function refer both to physiology and behavior as well as to the subjacent mechanisms related to morphology, biochemistry and genetics. They may be approached at the systemic, behavioral, cellular and molecular levels. This work intends to characterize these kinds of studies pointing to their relations with the analyis of behavior and learning.The analysis of how the environmental-organismic interrelationships affect the neural substrates of behavior is pointed as a very stimulating area for investigation.As interações entre os estímulos ambientais e as respostas de um organismo determinam as propriedades comportamentais que lhe garantem adaptação a diferentes situações e individualidade comportamental. A interação organismo-ambiente também diferencia e molda os circuitos neurais, que caracterizam a plasticidade e a individualidade neural do organismo. Os estudos sobre plasticidade neural incluem aqueles que manipulam o ambiente e analisam mudanças em circuitos neurais e outros que enfatizam recuperação comportamental após lesão do sistema nervoso. Diferentes questões relativas à fisiologia e ao comportamento, como também à morfologia, à bioquímica e à genética, são abordadas. Este trabalho procura caracterizar diferentes abordagens no estudo da plasticidade neural, indicando as suas relações com a análise do comportamento e da aprendizagem. A investigação dos efeitos que a interação organismo-ambiente produz sobre os sistemas neurais subjacentes ao comportamento é enfatizada como interessante.18719

Aprendizagem de discriminação operante em pombos (Columba livia) destelencefalados : implicações para o estudo da plasticidade neural

Orientadores: Elenice A. de Moraes Ferrari, Gerson ChadiTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: A situação de discriminação operante fornece uma linha de base comportamental adequada para a análise de efeitos de lesão neural em mamíferos e aves. O substrato neural do comportamento discriminativo inclui funções integratlvas de sIstemas telencefálicos e subtelencefálicos. O presente trabalho teve como objetivo estudar o processo de aprendizagem e a capacidade de reorganização anátomo-funcional de estruturas subtelencefalálicas em pombos destelencefalados. Foram analisados pombos submetidos a ablação de estruturas telencefálicas e ao processo de aprendizagem de discriminação operante (Grupo LA), à cirurgia simulada e à aprendizagem (Grupo SA), pombos submetidos somente à aprendizagem (Grupo NA) e pombos não lesado-não treinados (NN). A análise da aprendizagem foi realizada pelo condicionamento da resposta de bicar o disco em esquemas de reforçamento alimentar, contingências de discriminação sucessiva e de reversão da discriminação. Nas condições de discriminação e de reversão da discriminação treinamento continuou até a estabilidade do comportamento. Após o término dos procedimentos experimentais todos os pombos foram sacrificados, os cérebros perfundidos e preparados de acordo com a técnica de Klüver & Barrera. Pombos dos grupo NN e LA foram usados para análises morfométricas, Pombos lesados e não treinados (Grupo LNA), e submetidos à cirurgia simulada e não treinados (LSA) foram submetidos as análises imonohistoquímicas da proteína ácida fibrilar glial (GFAP) e do neurofilamento (NF). A avaliação morfométrica e imunohistoquímica foi realizada no núcleo Rotundo (NRt) e Teto Óptico (TeO). Os resultados da análise comportamental demonstraram que os pombos lesados aprenderam a discriminação e necessitaram de um maior número de sessões para a aquisição e para a estabilidade do comportamento (p<0,05). Entretanto, não responderam diferencialmente a Vermelho e Amarelo na condição de reversão, evidenciando ausência de aprendizagem (p<0,05). A morfometria demonstrou uma desorganização estrutural no TeO e uma alteração no número de neurônios e de vasos no NRt de pombos LA (p< 0.05). A análise imunohistoquímica mostrou que os pombos LNA tiveram uma ativação astrocitária no TeO e no Nrt (p<0,02) e um aumento no número e/ou tamanho dos processos celulares imunorreativos ao GFAP (p<0,02). Uma diminuição na imunorreatividade ao neurofilamento, que caracteriza degeneração neuronal, também foi observado nos pombos LNA em comparação com os pombos LSA. Em conjunto, os dados demonstram que os sistemas telencefálicos não são essenciais para a aprendizagem de discriminação, mas teria funções na aquisição do condicionameno da resposta de bicar e no processo de aprendizagem de reversão da discriminação. Estruturas subtelencefálicas parecem ser importantes para a organização e armazenamento da aprendizagem. As evidências de mudanças anátomo-funcionais em células neuronais e em astrócito sugerem mecanismos correlacionados com aprendizagem e plasticidade neural em sistemas subtelencefálicos, longo tempo após a lesãoAbstract: Operant discriminative behavior provides a useful baseline for analyzing the effects of lesions both for mammal and avian brains. The neural substrates of the discriminative behavior include integrative functions by telencephalic and subtelencephalic systems. The present work was conducted to analyze behavior under discrimination contingencies and morphological characteristics of visual pathway components in detelencephated pigeons. Adult pigeons divide into different groups according to lesion and learning conditions were used: pigeons submitted to telencephalic lesions and learning (LA), sham-Iesion-Iearning (SA), non-syrgery-Iearning (NA) or non-lesion-non learning (NN). Behavioral analysis was carried out through key pecking conditioning, operant discrimination and reversal discrimination learning training. After experimental procedure pigeons were perfused and their brains were used stained according to Klüver-Barrera techique. Pigeons LA and NN were submitted to morphometric analysis. Brains of nontrained lesioned pigeosn (LNA) and sham-Iesionedtrained pigeons (LSA) were submitted to immunohistochemical analysis of neurofilament (NF) and glial fibrillary acidic protein (GFAP). The morphometric and immunohistochemicalanalyses were realized in the Optic Tectum (OT) and nucleus Rotundus (Rt). LL and control group comparisons showed that lesioned birds had more sessions for key peck acquisition and steady-state behavior (p< 0.05). Rt increases were observed in perimeter, neuronal soma and vascularity (p< 0.05), contrasting with a decreased number ofneurons (p< 0.05). The OT analysis showed a major disorganization in celllayers and was associated to increased thickness of layers 1,2 e 3. The GFAP immunohistochemistry showed an astrocytic reaction in the Rt and OT (p<0,02). The NF immunohistochemistry demonstrated a decreased NF immunoreativity (IR) in the Rt in layers ofthe OT in lesioned pigeons The number ofNF immunoreactive (ir) nerve terminais was decreaesd in the analised regions. The overall data demonstrated that telencephalic systems are not essentiai for discrimination learning but have a function in the acquisition of key pecking and reversal learning. The long-term analysis of detelencephalated pigeons demonstrated a degeneration of the visual neuronal pathway and long lasting activation of astrocytes. These evidences of plastic changes of subtelencephalic systems after long-term detelencephalated suggest functional mechanisms correlated with learning and neural plasticity in pigeonsDoutoradoFisiologiaDoutor em Ciências Biológica

Effects of the a flavonoid-rich fraction on the acquisition and extinction of fear memory: Pharmacological and molecular approaches

The effects of flavonoids have been correlated with their ability to modulate the glutamatergic, serotoninergic and GABAergic neurotransmission; the major targets of these substances are N-methyl-D-aspartic acid receptor (NMDARs), serotonin type1A receptor (5-HT1ARs) and the gamma-aminobutyric acid type A receptors (GABAARs). Several studies showed that these receptors are involved in the acquisition and extinction of fear memory. This study assessed the effects of treatment prior to conditioning with a flavonoid-rich fraction from the stem bark of Erythrina falcata (FfB) on the acquisition and extinction of the conditioned suppression following pharmacological manipulations and on gene expression in the dorsal hippocampus (DH). Adult male Wistar rats were treated before conditioned fear with FfB, vehicle, an agonist or antagonist of the 5-HT1AR, GABAARs or the GluN2B-NMDAR or one of these antagonists before FfB treatment. The effects of these treatments on fear memory retrieval, extinction training and extinction retrieval were evaluated at 48, 72 and 98 h after conditioning, respectively. We found that activation of GABAARs and inactivation of GluN2B-NMDARs play important roles in the acquisition of lick response suppression. FfB reversed the effect of blocking GluN2B-NMDARs on the conditioned fear and induced the spontaneous recovery. Blocking the 5-HT1AR and the GluN2B-NMDAR before FfB treatment seemed to be associated with weakening of the spontaneous recovery. Expression of analysis of DH samples via qPCR showed that FfB treatment resulted in the overexpression of Htr1a, Grin2a, Gabra5 and Erk2 after the retention test and of Htr1a and Erk2 after the extinction retention test. Moreover, blocking the 5-HT1ARs and the GluN2B-NMDARs before FfB treatment resulted in reduced Htr1a and Grin2b expression after the retention test, but played a distinct role in Grin2a and Erk2 expression, according session evaluated. We show for the first time that the serotoninergic and glutamatergic receptors are important targets for the effect of FfB on the conditioned fear and spontaneous recovery, in which the ERK signaling pathway appears to be modulated. Further, these results provide important information regarding the role of the DH in conditioned suppression. Taken together, our data suggest that FfB represents a potential therapy for preventing or treating memor

Long-term astroglial reaction and neuronal plasticity in the subcortical visual pathways after a complete ablation of telencephalon in pigeons (Columba livia)

This paper analyzes the astroglial and neuronal responses in subtelencephalic structures, following a bilateral ablation of the telencephalon in the Columba livia pigeons. Control birds received a sham operation. Four months later the birds were sacrificed and their brains processed for glial fribillary acid protein (GFAP) and neurofilament immunohistochemistry, markers for astrocytes and neurons, respectively. Computer-assisted image analysis was employed for quantification of the immunoreactive labeling in the nucleus rotundus (N.Rt) and the optic tectum (OT) of the birds. An increased number of GFAP immunoreactive astrocytes were found in several subregions of the N.Rt (p .001), as well as in layers 1, 2cd, 3, and 6 of the OT (p .001) of the lesioned animals. Neurofilament immunoreactivity decreased massively in the entire N.Rt of the lesioned birds; however, remaining neurons with healthy aspect showing large cytoplasm and ramified branches were detected mainly in the periphery of the nucleus. In view of the recently described paracrine neurotrophic properties of the activated astrocytes, the data of the present study may suggest a long-lasting neuroglial interaction in regions of the lesioned bird brain far from injury. Such events may trigger neuronal plasticity in remaining brain structures that may lead spontaneous behavior recovery as the one promoted here even after a massive injury.1193384403CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçã

Long-Term Astroglial Reaction and Neuronal Plasticity in the Subcortical Visual Pathways After a Complete Ablation of Telencephalon in Pigeons (Columba livia)

This paper analyzes the astroglial and neuronal responses in subtelencephalic structures, following a bilateral ablation of the telencephalon in the Columba livia pigeons. Control birds received a sham operation. Four months later the birds were sacrificed and their brains processed for glial fribillary acid protein (GFAP) and neurofilament immunohistochemistry, markers for astrocytes and neurons, respectively. Computer-assisted image analysis was employed for quantification of the immunoreactive labeling in the nucleus rotundus (N.Rt) and the optic tectum (OT) of the birds. An increased number of GFAP immunoreactive astrocytes were found in several subregions of the N.Rt (p .001), as well as in layers 1, 2cd, 3, and 6 of the OT (p .001) of the lesioned animals. Neurofilament immunoreactivity decreased massively in the entire N.Rt of the lesioned birds; however, remaining neurons with healthy aspect showing large cytoplasm and ramified branches were detected mainly in the periphery of the nucleus. In view of the recently described paracrine neurotrophic properties of the activated astrocytes, the data of the present study may suggest a long-lasting neuroglial interaction in regions of the lesioned bird brain far from injury. Such events may trigger neuronal plasticity in remaining brain structures that may lead spontaneous behavior recovery as the one promoted here even after a massive injury.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Brazi

Plasticidade neural: relações com o comportamento e abordagens experimentais

As interações entre os estímulos ambientais e as respostas de um organismo determinam as propriedades comportamentais que lhe garantem adaptação a diferentes situações e individualidade comportamental. A interação organismo-ambiente também diferencia e molda os circuitos neurais, que caracterizam a plasticidade e a individualidade neural do organismo. Os estudos sobre plasticidade neural incluem aqueles que manipulam o ambiente e analisam mudanças em circuitos neurais e outros que enfatizam recuperação comportamental após lesão do sistema nervoso. Diferentes questões relativas à fisiologia e ao comportamento, como também à morfologia, à bioquímica e à genética, são abordadas. Este trabalho procura caracterizar diferentes abordagens no estudo da plasticidade neural, indicando as suas relações com a análise do comportamento e da aprendizagem. A investigação dos efeitos que a interação organismo-ambiente produz sobre os sistemas neurais subjacentes ao comportamento é enfatizada como interessante