Navegando por Palavras-chave "Inhibitory avoidance"
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- ItemAcesso aberto (Open Access)Avaliação da participação do hipocampo dorsal na plasticidade sináptica associada à expressão de pCREB nos núcleos da amígdala após a tarefa de esquiva inibitória(Universidade Federal de São Paulo (UNIFESP), 2019-07-25) Favaro, Vanessa Manchin [UNIFESP]; Oliveira, Maria Gabriela Menezes de [UNIFESP]; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4723159U8; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4447680J4; Universidade Federal de São Paulo (UNIFESP)The Inhibitory Avoidance (IA) - step-through and contextual fear conditioning (CFC) tasks are based on different types of associative learning, in which memories related to aversive events can be studied. The both tasks involve the association between stimuli, the conditioned stimulus, which can be the context where the animal is placed, and the unconditioned, as a foot shock, related to the fear conditioning. In particular, only the task of IA also involves the association between a behavior and a stimulus, this type of learning is relative to the instrumental conditioning. It is known that both tasks depend on the involvement of the amygdala, while the involvement of the hippocampus depends on the salience of contextual and spatial components present in these tasks. An earlier study from our laboratory showed that temporary dorsal hippocampal blockade not only decreased the animals' defensive behaviors in CFC but also decreased the expression of the phosphorylated cAMP response element binding protein (pCREB), a related transcription factor to synaptic plasticity and memory, in the amygdala nuclei. In this sense, the present study investigated the participation of the dorsal hippocampus in the synaptic plasticity associated with pCREB expression in the amygdala nuclei after the IA task. In Phase 1, significant differences were observed in the defensive behaviors, particularly in latency, freezing time in the white compartment and in the time in activity in animals submitted to immediate shock and the condition of habituation in the IA task. In addition, an increase in pCREB expression was observed in the lateral, basolateral and central nuclei of the amygdala after the EI-step-through task. In Phase 2, the results of the pharmacological experiments showed that the manipulation of different classes of hippocampal receptors did not affect the performance of the animals in the step-through IA task. In agreement with the pharmacological results, data obtained with the immunohistochemical technique showed that the expression of pCREB in the lateral, basolateral and central nuclei of the amygdala is independent of the participation of the hippocampus. Taken together, our results suggest that the interaction between hippocampus and amygdala in the step-through IA task is different when compared to CFC, possibly due to the instrumental component of learning.
- ItemSomente MetadadadosChronic corticosterone administration facilitates aversive memory retrieval and increases GR/NOS immunoreactivity(Elsevier B.V., 2014-07-01) Santos, Thays Brenner dos [UNIFESP]; Céspedes, Isabel Cristina [UNIFESP]; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Glucocorticoids are stress hormones that mediate the organism's reaction to stress. It has been previously proposed that the facilitation of emotional aversive conditioning induced by these hormones may involve nitric oxide-pathways. the purpose of the present study was to address this question. for that, male Wistar rats were surgically implanted with slow-release corticosterone (CORT) pellets (21 days) and tested in a step-down inhibitory avoidance task. Additional groups of animals were also submitted to the same treatment conditions and on the 21st day of treatment assayed for GR (glucocorticoid receptors)nNOS (neuronal nitric oxide synthase) immunoreactivity (GRi-nNOSi) or measurements of plasma CORT. Results showed that CORT treatment induced facilitation of step-down inhibitory avoidance. This same treatment also significantly increased CORT plasma levels and GRi in the medial, basolateral and basomedial amygdala, in the paraventricular hypothalamic nucleus (PVN), in the ventral and dorsal dentate gyrus, in the ventral CA1 region and in the dorsal CA1 and CA3 regions. Furthermore, nNOSi and GRi-nNOSi were significantly increased by CORT treatment in the medial amygdala and basolateral amygdaloid complex, in the PVN, subiculum, in the dorsal CA3 region and in the ventral CA1 and CA3 regions. These results indicate that the facilitation of aversive conditioning induced by CORT involves GR-nNOS pathways activation, what may be of relevance for a better understanding of stress-related psychiatric conditions. (C) 2014 Elsevier B.V. All rights reserved.
- ItemAcesso aberto (Open Access)Os efeitos da restrição crônica de sono sobre o desempenho de ratos na tarefa de esquiva inibitória(Universidade Federal de São Paulo (UNIFESP), 2009-05-27) Carvalho, Adriana Neves da Silva [UNIFESP]; Hipólide, Débora Cristina [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)There are numerous studies suggesting that sleep deprivation induce deleterious effects in the rat performance on memory tasks. However, there are but a few studies on the effects of experimental chronic sleep restriction on those tasks. Recently, we observed that rats submitted to a protocol of chronic sleep restriction in which the animals were sleep-deprived for 18h/day and allowed to sleep for 6h in the light phase, during 21 consecutive days, showed no deficits on memory. Here, we investigated the possibility that chronic sleep restriction would impair the performance on the inhibitory avoidance task when rats are allowed to sleep in different circadian phases. Rats were deprived of sleep using the platform method and then trained in a step-through inhibitory avoidance task. One hour after training, the animals were given a retention test. Neither 6h of sleep opportunity (light and dark phase) nor 4h sleep opportunity (light phase) induced impairment on inhibitory avoidance. However, we observed a deficit on performance on inhibitory avoidance task after 4h of sleep opportunity in the dark phase, when there is no coincidence between circadian and homeostatic pressure. Also, 3h of sleep, even in the light phase were not enough to prevent the memory impairment. These results suggest that the memory impairment of sleep deprived rats could be a result of disrupted coincidence between circadian and homeostatic drivers to sleep.
- ItemSomente MetadadadosFacilitation of 5-HT2A/2C-mediated neurotransmission in the ventromedial hypothalamic nucleus decreases anxiety in the elevated T-maze(Elsevier B.V., 2011-01-20) Silva, E. S. da [UNIFESP]; Poltronieri, Selma Conceição; Nascimento, Juliana Olivetti Guzman [UNIFESP]; Zangrossi Junior, Helio; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Ctr Univ Votuporanga UNIFEV; Universidade de São Paulo (USP)Previous evidence has shown that facilitation of GABA/benzodiazepine-mediated neurotransmission in the ventromedial hypothalamus (VMH) inhibits both escape and inhibitory avoidance responses generated in the elevated T-maze test of anxiety (ETM). These defensive behaviors have been associated with panic and generalized anxiety, respectively. Aside from GABA/benzodiazepine receptors, the VMH also contains a significant number of serotonin (5-HT) receptors, including 1A, 2A and 2C subtypes. the purpose of the present study was to investigate the effect of the activation of 5-HT1A and 5-HT2A/2C receptors in the VMH on defensive behavioral responses in rats submitted to the ETM. for that, male Wistar rats were treated intra-VMH with the 5-HT1A agonist 8-OH-DPAT, with the 5-HT2A/2C agonist DOI, with the 5-HT2C selective agonist MK-212, or with the 5-HT2A/2C antagonist ketanserin and 10 min after were submitted to the ETM. Results showed that both DOI and MK-212 significantly decreased avoidance measurements, an anxiolytic-like effect, without altering escape. 8-OH-DPAT and ketanserin were without effect, although the last drug attenuated the effects of DOI. None of the drugs altered locomotor activity in an open field. These results suggest that 5-HT2A/2C receptors of the VMH are involved in the regulation of inhibitory avoidance and might be of relevance to the physiopathology of generalized anxiety. (C) 2010 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosGABA/benzodiazepine receptors in the ventromedial hypothalamic nucleus regulate both anxiety and panic-related defensive responses in the elevated T-maze(Elsevier B.V., 2007-09-14) Bueno, Cintia Heloina; Zangrossi Junior, Helio; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)It has been shown that facilitation of GABA-mediated neurotransmission in the medial nucleus of the amygdala and the dorsal periaqueductal gray (dPAG) inhibits the escape, but not the inhibitory avoidance response generated in the elevated T-maze test of anxiety (ETM). These defensive behaviors have been associated with panic and generalized anxiety, respectively. Previous evidence indicates that the dorsomedial part of the ventromedial hypothalamus (VMHdm), which is interconnected with these two brain areas, is also part of the neurobiological substrate controlling escape behavior. in the present study, we investigated in male Wistar rats whether the intra-VMHdm injection of GABA-modulating drugs differently affect the two defensive tasks measured in the ETNI. the results showed that the microinjection of the benzodiazepine (BZD) receptor agonist midazolam (10, 20 and 40 nmol), the GABA(A) receptor agonist muscimol (2, 4 and 8 nmol) or the GABA(B) receptor agonist baclofen (2, 4 and 8 nmol) impaired inhibitory avoidance and escape performance, an anxiolytic and panicolytic-like effect, respectively. On the other hand, local administration of the BZD inverse agonist FG 7142 (20, 40 and 80 pmol) facilitated both behaviors, suggesting anxiogenic and panicogenic-like effects. These results were not due to motor alterations, since the drugs did not affect exploratory behavior in an open field. the data suggest that GABA(A)/BZD and GABAB receptors within the VMHdm are involved not only in the control of panic-related, but also of anxiety-related behaviors. (c) 2007 Elsevier Inc. All fights reserved.
- ItemAcesso aberto (Open Access)Histamina Hipocampal, Aprendizagem e Memória(Universidade Federal de São Paulo (UNIFESP), 2010) Goulart, Carolina de Souza [UNIFESP]; Medalha, Carla Christina [UNIFESP]; http://lattes.cnpq.br/1315289589167724; http://lattes.cnpq.br/7966349082379717; Universidade Federal de São Paulo (UNIFESP)A neuroplasticidade é a capacidade do SNC de alterar a sua estrutura com base nas experiências, responsável pelo mecanismo de aprendizagem. Estudos sugerem que drogas e neurotransmissores que participam dos processos de memória e aprendizagem são de fundamental importância para o entendimento do processo de recuperação após lesão de SNC. O presente estudo visa analisar as ações do sistema histaminérgico hipocampal sobre os processos de aquisição e consolidação da memória, em um teste de esquiva. Ratos Wistar machos foram implantados com cânulas nas regiões ventral e dorsal do hipocampo e treinados em um paradigma de esquiva inibitória. O animal foi individualmente colocado na plataforma, e no momento em que colocava as quatro patas no assoalho metálico, um choque foi liberado nas patas por 2s (0,4 mA; 40V). O procedimento era repetido até o rato permanecer 50s na plataforma. A latência de descida foi registrada e imediatamente após o treino os grupos de animais receberam o tratamento com histamina, salina (controle), coinfusão de histamina e antagonistas antagonistas receptores H1 (Pirilamina; 10,0 nmol/região) e H2 (Ranitidina; 20,0 nmol/região) no hipocampo dorsal ou ventral. Após 24 horas foi feito o teste no qual a evocação da memória foi testada por meio da repetição do procedimento de esquiva. A retenção da memória foi verificada através da latência, em segundos, do treino e do teste do animal da caixa de esquiva. Foi encontrado que a redução da atividade histaminérgica no hipocampo ventral, a partir da injeção intra de ranitidina foi capaz de reverter à tendência a extinção de memória aversiva propiciada pela histamina
- ItemSomente MetadadadosM1 muscarinic receptors are necessary for retrieval of remote context fear memory(Pergamon-Elsevier Science Ltd, 2017) Patricio, Rafael Rodisanski [UNIFESP]; Kramer Soares, Juliana Carlota [UNIFESP]; Menezes Oliveira, Maria Gabriela [UNIFESP]Several studies have investigated the transition of consolidation of recent memory to remote memory in aversively motivated tasks, such as contextual fear conditioning (CFC) and inhibitory avoidance (IA). However, the mechanisms that serve the retrieval of remote memories, has not yet been fully understood. Some evidences suggest that the central cholinergic system appears be involved in the modulation of these processes. Therefore, the present study aimed to investigate the effects of a pre-test administration of dicyclomine, a high-affinity M1 muscarinic receptor antagonist, on the retrieval of remote memories in fear conditioning and IA tasks. Male Wistar rats were trained, and after 1 or 28 days, the rats received dicyclomine (16 or 32 mg/lcg, intraperitoneally, i.p.) and were tested in CFC, tone fear conditioning (TFC) and IA tasks. At both time intervals, 32 mg/kg dicydomine induced impairment of CFC. In TFC task only the performance of the rats 28 days after training was impaired. The IA task was not affected in any of the studied intervals. These findings suggest a differential contribution of muscarinic receptors on recent and remote memories retrieval revealing a more generalized role in remote memory. (C) 2016 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosMultiple trial inhibitory avoidance acquisition and retrieval are resistant to chronic stress(Elsevier Science Bv, 2018) Raya, J. [UNIFESP]; Girardi, C. E. N. [UNIFESP]; Esumi, L. A. [UNIFESP]; Ferreira, L. B. T. [UNIFESP]; Hipolide, D. C. [UNIFESP]Chronic mild stress (CMS) is a widely accepted animal model relevant to depression that among other consequences, is chiefly known to induce anhedonia, often assessed as decreased preference for sucrose solution. CMS is also known to affect cognition, particularly memory tasks. In this study we have employed the multiple trial inhibitory avoidance memory task (MTIA) to assess CMS effects on memory acquisition and retrieval. MTIA consists of repeated exposures to the unconditioned stimulus until a learning criterion is reached. Wistar rats underwent CMS for 5 weeks, and sucrose consumption was assessed once a week. At the end of CMS, animals were evaluated in the MTIA task. Overall decreased sucrose solution preference was highly variable. Further analyses showed that a subset of animals expressed resilience while another subset was sensitive to stress. CMS did not affect the number of acquisition sessions before reaching criterion or retrieval latency of MTIA task in neither sensitive nor resilient groups. Although tasks that assess learning ability in animal models relevant to depression indicate cognitive deficits, the ability to learn the association between compartment crossing and the aversive electric foot shock, which is strongly dependent on emotional aspects, was intact.