Aprendizado espacial-temporal em um ambiente complexo sem restrição alimentar em ratos

Timeplace learning is the capacity of organisms to associate both space and time with a biological relevant stimulus such as food. Experiments are usually done with food restricted animals due to the belief that food system activation is necessary for timeplace learning. Another line of thought suggest that, in addition to food system activation, response cost should be increased to effectively allow timeplace discrimination. The purpose of this experiment was to test whether a complex environment, which presumably implied in a heightened response cost, would facilitate timeplace association in satiated rats using a highly palatable food as reward. Nine rats were trained in a timeplace task for 30 nonconsecutive days. A large experimental box (1x1m) divided in four compartments was used. To access each compartment the animal had to overcome a series of obstacles such as ramps, staircases and mazes. Two feeders localized in opposite compartments were rewarded with sunflower seeds in two daily sessions. One feeder offered the reward during the morning sessions while the second feeder in afternoon sessions. After the 15th day of training, the animals began to show a preference for the correct feeder during the correct time of day expressed by increased frequency of visits as well as lower latency to access the feeders. These results suggest that satiated animals are also capable of learning a timespace task as far as the experimental context is complex enough to result in a higher response cost

Efeitos da alteração dos níveis de ansiedade no desempenho de ratos em uma tarefa de discriminação apetitiva

The plus-maze discriminative avoidance paradigm has been used to study the relationship between aversive memory and anxiety. The present study aims to verify if the elevated plus-maze can provide information about appetitive memory and anxiety, through a task motivated by food reward. Animals were allowed to explore an elevated plus-maze and received reinforcement in one of the enclosed arms. In a test session performed 24h later, in the absence of reward, rats showed preference for the previously rewarded enclosed arm over the neutral enclosed arm. The administration of diazepam and pentylenetetrazole before training induced, respectively, anxiolytic and anxiogenic effects (as evaluated by open-arm exploration). Both drugs induced amnestic effects, i.e., lack of preference for the rewarded arm in the test session. The results suggest that appetitive memory can be influenced by anxiety levels as well. The plus-maze appetitive discrimination task seems to be a useful model to investigate the relationship between memory and anxiety

Déficits de memória induzidos por baixas doses de reserpina em ratos: possível relação com prejuízos no processamento emocional na Doença de Parkinson

We have recently verified that the monoamine depleting drug reserpine at doses that do not modify motor function - impairs memory in a rodent model of aversive discrimination. In this study, the effects of reserpine (0.1-0.5 mg/kg) on the performance of rats in object recognition, spatial working memory (spontaneous alternation) and emotional memory (contextual freezing conditioning) tasks were investigated. While object recognition and spontaneous alternation behavior were not affected by reserpine treatment, contextual fear conditioning was impaired. Together with previous studies, these results suggest that mild monoamine depletion would preferentially induce deficits in tasks involved with emotional contexts. Possible relationships with cognitive and emotional processing deficits in Parkinson disease are discussed

Atividade multimodal no córtex sensorial primário de ratos.

The currently accepted model of sensory processing states that different senses are processed in parallel, and that the activity of specific cortical regions define the sensorial modality perceived by the subject. In this work we used chronic multielectrode extracellular recordings to investigate to which extent neurons in the visual and tactile primary cortices (V1 and S1) of anesthetized rats would respond to sensory modalities not traditionaly associated with these cortices. Visual stimulation yielded 87% of responsive neurons in V1, while 82% of S1 neurons responded to tactile stimulation. In the same stimulation sessions, we found 23% of V1 neurons responding to tactile stimuli and 22% of S1 neurons responding to visual stimuli. Our data supports an increasing body of evidence that indicates the existence multimodal processing in primary sensory cortices. Our data challenge the unimodal sensory processing paradigm, and suggest the need of a reinterpretation of the currently accepted model of cortical hierarchy.

Sincronização dos ritmos de atividade motora e temperatura central à disponibilidade de glicose em ratos

Food is essential for the survival of all animals. Its temporal availability is an important enviromental cue for the behavioral and physiological organization throughout the 24 hours of day in different species. Rats and mice, for example, show increased locomotion in the hours before food availability when it is presented in a recurrent manner, a behavior named foodanticipatory activity. Several lines of evidence indicate that this anticipation is mediated by a circadian oscillator. In this work, based on the hypothesis that pre- or post-ingestive humoral signals are involved in the entrainment process, we tested whether the daily intake of glucose is sufficient to induce anticipatory activity in rats. The rhythms of motor activity and central temperature were recorded in animals undergoing 10 days of temporal glucose (solution at 50%) or chow restriction in light-dark (LD) and constant darkness (DD). Animals under temporal glucose restriction increase motor activity and and central temperature in the hours preceding glucose availability and such aticipation is extremely similar to that observed in animals under temporal chow restriction. Glucose ingestion is, therefore, a sufficient temporal cue to induce anticipation in rats. It is possible that the increase in plasma glucose after food ingestion constitutes one of the signals involved in the behavioral entrainment process to food availability

Alterações cognitivas em ratos infectados com Toxoplasma gondii

Toxoplasma gondii is a protozoan parasite that induces behavioral changes in rodents. The aim of this study was to evaluate the effect of infection by T. gondii during the chronic phase in working memory and impulsivity in rodents as well as the effect of antipsychotics to reverse any behavioral changes resulting from infection. Female Wistar rats (n = 40) were infected with 25 cysts of the strain ME-49 T. gondii after 4 months the animals were subjected to behavioral tests: tolerance to delay gratification, in which the animal must choose between two rewards, a smaller and more immediate, but delayed and the test of spontaneous alternation, in which the animal must use spatial cues to remember previously visited arms. Antipsychotic drugs were intraperitoneally administered during the testing of the behavioral experiments, the antipsychotic is haloperidol (1.5 mg / kg) administered 60 min before the start of the session and the antipsychotic clozapine (2.5 mg / kg) 30 min before. Animals infected with the parasite did not show operating deficits of memory, and motor impairment did not develop, however motor impairment was observed only in animals treated with haloperidol. It was found that administration of clozapine and haloperidol increased the percentage of alternation in infected and control groups in task switching espontânea.Não no distinction between control animals and infected the test of tolerance to delay gratification in relation to the percentage of choices greatest reward, during the pre-training and training, in which there is a delay of 15 s to access the great reward, however it was observed that infected animals prefer the greatest reward, when there is a delay of 30 s when compared to control group. The administration of clozapine possible that infected animals chose the greatest reward in the delay of 30 seconds during the test. These data suggest that infected mice do not exhibit deficits in working memory and that clozapine has therapeutic efficacy in improving cognitive performance of mice infected

Efeitos do tratamento com lítio na memória aversiva, comportamentos relacionados à ansiedade e depressão e na expressão de BDNF em ratos

Lithium (Li) is the first choice to treat bipolar disorder, a psychiatric illness characterized by mood oscillations between mania and depression. However, studies have demonstrated that this drug might influence mnemonic process due to its neuroprotector, antiapoptotic and neurogenic effects. The use of Li in the treatment of cognitive deficits caused by brain injury or neurodegenerative disorders have been widely studied, and this drug shows to be effective in preventing or even alleviating the memory impairment. The effects of Li on anxiety and depression are controversial and the relationship of the effects of lithium on memory, anxiety and depression remain unknown. In this context, this study aims to: evaluate the effects of acute and chronic administration of lithium carbonate in aversive memory and anxiety, simultaneously, using the plus maze discriminative avoidance task (PMDAT); test the antidepressant effect of the drug through the forced swimming test (FS) and analyze brainderived neurotrophic factor (BDNF) expression in structures related to memory and emotion. To evaluation of the acute effects, male Wistar rats were submitted to i.p. administration of lithium carbonate (50, 100 or 200 mg/kg) one hour before the training session (PMDAT) or lithium carbonate (50 or 100 mg/kg) one hour before the test session (FS). To evaluation of the chronic effects, the doses administered were 50 or 100 mg/kg or vehicle once a day for 21 days before the beginning of behavioral tasks (PMDAT and FS). Afterwards, the animals were euthanized and their brains removed and submitted to immunohistochemistry procedure to quantify BDNF. The animals that received acute treatment with 100 and 200 mg/kg of Li did not discriminated between the enclosed arms (aversive and non-aversive) in the training session of PMDAT, showing that these animal did not learned the task. This lack of discrimination was also observed in the test session, showing that the animals did not recall the aversive task. We also observed an increased exploration of the open arms of these same groups, indicating an anxiolytic effect. The same groups showed a reduction of locomotor activity, however, this effect does not seem to be related with the anxiolytic effect of the drug. Chronic treatment with Li did not promote alterations on learning or memory processes. Nevertheless, we observed a reduction of open arms exploration by animals treated with 50 mg/kg when compared to the other groups, showing an anxiogenic effect caused by this dose. This effect it is not related to locomotor alterations since there were no alterations in these parameters. Both acute and chronic treatment were ineffective in the FS. Chronic treatment with lithium was not able to modify BDNF expression in hippocampus, amygdala and pre-frontal cortex. These results suggest that acute administration of lithium promote impairments on learning in an aversive task, blocking the occurrence of memory consolidation and retrieval. The reduction of anxiety following acute treatment may have prevented the learning of the aversive task, as it has been found that optimum levels of anxiety are necessary for the occurrence of learning with emotional context. With continued, treatment the animals recover the ability to learn and recall the task. Indeed, they do not show differences in relation to control group, and the lack of alterations on BDNF expression corroborates this result. Possibly, the regimen of treatment used was not able to promote cognitive improvement. Li showed acute anxiolytic effect, however chronic administration 4 promoted the opposite effect. More studies are necessary to clarify the potential beneficial effect of Li on aversive memory

Caminhos e descaminhos da adesão ao tratamento anti-hipertensivo :um estudo com usuários do Pacha (Programa de Assistência e Cuidado da Hipertensão Arterial) do Hospital Universitário Onofre Lopes

The high blood pressure is a multifactorial chronic disease which possesses emotional and social features in the illness appearance and evolution and in the adherence to the treatment which involves a decision-making through patient so that he or she process the necessary changes on harmful living habits. Adhesion, traditionally, it is referred to the patient to answer to the doctor orientations or of other health professional, about the appearance to the appointment with a doctor, about the use of medicine or lifestyle changes and maintaining this adhesion is the main problem to be overcame. It is expected the adhesion will ever be a continual, stable and satisfactory action, disregarding the complexity of subjectivity processes which permeate the sicken. This research aimed to investigate the difficulties which the person with high blood pressure has to adhere to the treatment, from the signification processes which give sense to the actions dealing with the adhesion. The study was carried out with 48 users of assistance program to the high blood pressure patient from Hospital Universitário from Natal RN, between 40-65 age. The answers were submitted to a double analysis process: 1) answer systematization in categories and codes and admission in statistical program SPSS (Statistical Package of Social Science), for generation of descriptive statistics; 2) Sense and signification analysis which permeated the deepener statement and interpretatively. The greater difficulties found are present on low-salt and law-calorie diets, in the dealing with everyday feeling and stress, being these factors cited as direct motive to the high blood pressure, regardless of interviewee s sex. It is observed there is not adhesion, but adhering, as an experienced everyday process. This work contributes with its results, assessing the used strategies by program with the aim of increasing the adhesion rates

Frequencia de enteroparasitoses em usuários do servico público de saúde na mesorregião do oeste potiguar

Em um mundo de grande pobreza, as enteroparasitoses podem exercer um papel importante no que se refere às desigualdades sociais, pois estas mazelas se apresentam, em sua grande maioria, na população mais carente. Estas mesmas doenças causam inúmeros casos de faltas ao trabalho e a escola, gerando preocupação dos profissionais de saúde, já que estes parasitas podem agravar ou desencadear quadros de anemia e desnutrição. O trabalho procurou pesquisar a prevalência de enteroparasitas na Mesorregião do Oeste Potiguar, em uma população que utiliza o sistema público de saúde, buscando associar as variáveis, como: sexo, faixa etária, período sazonal, renda familiar e número de parasitas. Foi utilizada a técnica de Hofmann (sedimentação espontânea) e o material fecal foi analisado pelos funcionários do Laboratório Central de Mossoró e Pau dos Ferros. Foi realizado no período de 02 de março de 2010 a 28 de março de 2011 o exame coprológico em 16.246 pessoas no laboratório Central de Mossoró (Lacen) e Pau dos Ferros, RN. A análise dos exames mostrou que 69,23% dos infectados eram mulheres e 33,07% eram homens. A maior prevalência ocorreu com Endolimax nana (41,61%), seguido de Entamoeba coli (18,46%) e Giardia lamblia (18,59%) em 3.407 parasitas encontrados. Dentre os exames realizados, o Endolimax nana foi o mais prevalente entre os organismos encontrados. A diferença nos resultados entre mulheres e homens pode determinar um foco domiciliar, pelo descaso do poder público com as políticas de saneamento básico e falta de higiene da população, e pela atividade das mesmas com trabalhos domésticos

Caracterização do perfil do ciclo sono-vigília em ratos sob dessincronização forçada

The circadian behavior associated with the 24 hours light-dark (LD) cycle (T24) is due to a circadian clock , which in mammals is located in the hypothalamic suprachiasmatic nucleus (SCN). Under experimental conditions in which rats are espoused to a symmetric LD 22h cycle (T22) the two SCN regions, ventrolateral (vl) and dorsomedial (dm), can be functionally isolated, suggesting that each region regulates distinct physiological and behavioral components. The vl region regulates the locomotor activity and slow wave sleep (SWS) rhythms, while the dm region assures the body temperature and paradoxical sleep (PS) rhythms regulation. This research aimed to deepen the knowledge on the functional properties of circadian rhythmicity, specifically about the internal desynchronization process, and its consequences to locomotor activity and body temperature rhythms as well as to the sleep-wake cycle pattern in rats. We applied infrared motion sensors, implanted body temperature sensors and a telemetry system to record electrocorticogram (ECoG) and electromyogram (EMG) in two rat groups. The control group under 24h period LD cycle (T24: 12hL-12hD) to the baseline record and the experimental group under 22h period LD cycle (T22: 11hL- 11hD), in which is known to occur the uncoupling process of the circadian locomotor activity rhythm where the animals show two distinct locomotor activity rhythms: one synchronized to the external LD cycle, and another expressed in free running course, with period greater than 24h. As a result of 22h cycles, characteristic locomotor activity moment appear, that are coincidence moments (T22C) and non coincidence moments (T22NC) which were the main focus or our study. Our results show an increase in locomotor activity, especially in coincidence moments, and the inversion of locomotor activity, body temperature, and sleep-wake cycle patterns in non coincidence moments. We can also observe the increase in SWS and decrease in PS, both in coincidence and non coincidence moments. Probably the increases in locomotor activity as a way to promote the coupling between circadian oscillators generate an increased homeostatic pressure and thus increase SWS, promoting the decreasing in PS

Avaliação de uma fração polissacaridica da alga Lobophora variegata (Lamouroux) em modelo de artrite induzida em ratos por Zymosan

Fucans seaweed Lobophora variegata estructures are known for their chemical and biological properties. In this study, we analyzed, the action of fucans L. variegata and the fractions purified with acetone in Zymosan-induced arthritis. After differential fractionation with acetone, six fractions were obtained and named F0.3, F0.5, F0.8, F1, F1.5 and F2. The results showed that the fraction F1 showed high yield (51.9%) and was chosen for studies of antioxidant activity and induced arthritis. Nuclear magnetic resonance (NMR) of 13C showed signals at 103.3 and 15.78 ppm that are assigned to links β13 galactose and of the C6 methyl fucose, respectively. The infrared (IR) showed absorbance at 1238 and 850 cm-1 which are attributed to sulfate. The fraction F1 showed antioxidant activities in vitro. For analysis of inflammatory parameters chosen the polysaccharide was administered in different doses (25, 50 and 75 mg / kg ip, per body weight) and diclofenac sodium (5 mg / kg ip) and L-NAME (25 mg / kg ip) in groups of animals (n = 6). After 6 h, were analyzed for cellular influx and levels of nitrite. In experiment five days, were made analysis of swelling and serum TNF-α. Histopathological analysis were performed for confirmation of results. The fraction F1 (25, 50 and 75 mg / kg ip) reduced the cellular influx (52.1 to 96.7%) and nitric oxide levels (27.2 - 39%) compared to control group. The reduction of edema (63.4 - 100%) and serum TNF-α (p <0.001) were observed when the polysaccharide F1 administered at a dose (50 mg / kg) These results suggest that these heterofucanas of Lobophora variegata have besides the activity antioxidant and potential anti-inflammatory activity in arthritis induced by zymosan