One physical exercise session promotes recognition learning in rats with cognitive deficits related to amyloid beta neurotoxicity.

Alzheimer's disease is a progressive neurodegenerative pathological process that causes memory loss and cognitive impairment. One of the pathological characteristics of Alzheimer's disease is the amyloid-ß protein aggregation on the brain. The regular practice of physical exercise is a consolidated strategy on the prevention of cognitive deficits; however, little is known about the effects of acute exercise on memory. We hypothesize that one physical exercise session could act as a modulator of learning. Here we investigated the effects of one single session of running (aerobic) or strength (anaerobic) exercise on memory deficits related to neurotoxicity induced by amyloid-ß. Male Wistar rats were submitted to stereotaxic surgery to intrahippocampal infusion of amyloid-ß protein or saline (control). Ten days after the surgery the rats were submitted to the object recognition (OR) memory task. Immediately after the OR learning session, some rats were submitted to one treadmill running or strength exercise session. Then, the animals were submitted to memory tests 24 h, 7, and 14 days after the OR learning. We demonstrated that one physical exercise session, both aerobic as anaerobic, performed after learning improves learning and memory, promoting memory persistence in control rats and memory consolidation in rats submitted to amyloid-ß neurotoxicity model. Notably, the effects of the aerobic exercise session seem to be more prominent, since they also reflect in an improvement of object discrimination index for 7 days in control animals. We verified that the mechanisms involved in the effects of aerobic exercise include the dopaminergic system activation. The mechanisms involved in the anaerobic exercise effects seem to be others since no alterations on hippocampal dopamine or noradrenaline levels were detected.

Egg White Hydrolysate as a functional food ingredient to prevent cognitive dysfunction in rats following long-term exposure to aluminum.

Aluminum (Al), which is omnipresent in human life, is a potent neurotoxin. Here, we have tested the potential for Egg White Hydrolysate (EWH) to protect against changes in cognitive function in rats exposed to both high and low levels of Al. Indeed, EWH has been previously shown to improve the negative effects induced by chronic exposure to heavy metals. Male Wistar rats received orally: Group 1) Low aluminum level (AlCl3 at a dose of 8.3 mg/kg b.w. during 60 days) with or without EWH treatment (1 g/kg/day); Group 2) High aluminum level (AlCl3 at a dose of 100 mg/kg b.w. during 42 days) with or without EWH treatment (1 g/kg/day). After 60 or 42 days of exposure, rats exposed to Al and EWH did not show memory or cognitive dysfunction as was observed in Al-treated animals. Indeed, co-treatment with EWH prevented catalepsy, hippocampal oxidative stress, cholinergic dysfunction and increased number of activated microglia and COX-2-positive cells induced by Al exposure. Altogether, since hippocampal inflammation and oxidative damage were partially prevented by EWH, our results suggest that it could be used as a protective agent against the detrimental effects of long term exposure to Al.

Effect of green tea extract supplementation on exercise-induced delayed onset muscle soreness and muscular damage.

Previous studies addressed the antioxidant and anti-inflammatory role of compounds from green tea in different human tissues. Positive antioxidant and anti-inflammatory effects were described for brain tissues. Whether similar effects are observed in the skeletal muscle, green tea supplementation could be a strategy to reduce delayed onset muscle soreness resultant of exercise. Here we determine the effect of green tea extract supplementation on exercise-induced muscle soreness, muscle damage and oxidative stress. We performed a randomized triple blind placebo control study. Twenty non-trained men performed sessions of exercise to induce delayed onset muscle soreness in the triceps sural muscle group before and after 15 days of supplementation (500 mg/day) with green tea extract (n = 10) or a placebo (n = 10). Muscle soreness was evaluated using a visual scale. Blood samples were taken at different moments to determine serum blood markers of muscle damage, oxidative stress and antioxidant status. We found that exercise induced delayed onset muscle soreness. Supplementation reduced muscle damage but muscle soreness did not change. Plasma oxidative damage marker and antioxidant status did not show an effect of supplementation. As a conclusion, green tea extract supplementation did not reduce the sensation of delayed onset muscle soreness but reduces the marker of muscle damage after exercise. It suggests the green tea extract supplementation has positive effects on muscle recovery after strenuous exercise.

Short-term green tea supplementation prevents recognition memory deficits and ameliorates hippocampal oxidative stress induced by different stroke models in rats.

This study investigated the effect of green tea (GT) on short and long term declarative memory and oxidative damage induced by transient ischemia-reperfusion (IR) and intracerebral hemorrhage (ICH) in rats. Male Wistar rats were divided into 8 groups of 10 according the stroke type induced: Sham IR, Sham IR+GT, IR, IR+GT, Sham ICH, Sham ICH+GT, ICH, ICH+GT. Supplementation with GT was initiated 10days before stroke surgery and continuous for 6days after (GT dose 400mg/kg). Short (STM) and long term memory (LTM) we evaluated with object recognition task (OR) and hippocampus were used to evaluate parameters related to oxidative stress (ROS, lipid peroxidation and total antioxidant capacity). The rats subjected to IR and ICH showed STM and LTM deficits and GT intervention prevented it in both stroke models. IR and ICH induced increase on ROS levels in hippocampus. ICH increased the lipid peroxidation in hippocampus and the GT supplementation avoided it. IR induced decrease on total antioxidant capacity and GT prevented it. These results reveal that GT supplementation presents a neuroprotective role, attenuates redox imbalance and might have a beneficial impact on cognitive function after stroke.

Aluminum Exposure at Human Dietary Levels for 60 Days Reaches a Threshold Sufficient to Promote Memory Impairment in Rats.

Aluminum (Al) is a significant environmental contaminant. While a good deal of research has been conducted on the acute neurotoxic effects of Al, little is known about the effects of longer-term exposure at human dietary Al levels. Therefore, the purpose of this study was to investigate the effects of 60-day Al exposure at low doses for comparison with a model of exposure known to produce neurotoxicity in rats. Three-month-old male Wistar rats were divided into two major groups: (1) low aluminum levels, and (2) a high aluminum level. Group 1 rats were treated orally by drinking water for 60 days as follows: (a) control-received ultrapure drinking water; (b) aluminum at 1.5 mg/kg b.w., and (c) aluminum at 8.3 mg/kg b.w. Group 2 rats were treated through oral gavages for 42 days as follows: (a) control-received ultrapure water; (b) aluminum at 100 mg/kg b.w. We analyzed cognitive parameters, biomarkers of oxidative stress and acetylcholinesterase (AChE) activity in hippocampus and prefrontal cortex. Al treatment even at low doses promoted recognition memory impairment seen in object recognition memory testing. Moreover, Al increased hippocampal reactive oxygen species and lipid peroxidation, reduced antioxidant capacity, and decreased AChE activity. Our data demonstrate that 60-day subchronic exposure to low doses of Al from feed and added to the water, which reflect human dietary Al intake, reaches a threshold sufficient to promote memory impairment and neurotoxicity. The elevation of oxidative stress and cholinergic dysfunction highlight pathways of toxic actions for this metal.

Physical exercise prevents short and long-term deficits on aversive and recognition memory and attenuates brain oxidative damage induced by maternal deprivation.

It is known from previous research that physical exercise prevents long-term memory deficits induced by maternal deprivation in rats. But we could not assume similar effects of physical exercise on short-term memory, as short- and long-term memories are known to result from some different memory consolidation processes. Here we demonstrated that, in addition to long-term memory deficit, the short-term memory deficit resultant from maternal deprivation in object recognition and aversive memory tasks is also prevented by physical exercise. Additionally, one of the mechanisms by which the physical exercise influences the memory processes involves its effects attenuating the oxidative damage in the maternal deprived rats' hippocampus and prefrontal cortex.

Facilitation of fear extinction by novelty depends on dopamine acting on D1-subtype dopamine receptors in hippocampus.

Extinction is the learned inhibition of retrieval. Recently it was shown that a brief exposure to a novel environment enhances the extinction of contextual fear in rats, an effect explainable by a synaptic tagging-and-capture process. Here we examine whether this also happens with the extinction of another fear-motivated task, inhibitory avoidance (IA), and whether it depends on dopamine acting on D1 or D5 receptors. Rats were trained first in IA and then in extinction of this task. The retention of extinction was measured 24 h later. A 5-min exposure to a novel environment 30 min before extinction training enhanced its retention. Right after exposure to the novelty, animals were given bilateral intrahippocampal infusions of vehicle (VEH), of the protein synthesis inhibitor anisomycin, of the D1/D5 dopaminergic antagonist SCH23390, of the PKA inhibitor Rp-cAMP or of the PKC inhibitor Gö6976, and of the PKA stimulator Sp-cAMP or of the PKC stimulator PMA. The novelty increased hippocampal dopamine levels and facilitated the extinction, which was inhibited by intrahippocampal protein synthesis inhibitor anisomysin, D1/D5 dopaminerdic antagonist SCH23390, or PKA inhibitor Rp-cAMP and unaffected by PKC inhibitor Gö6976; additionally, the hippocampal infusion of PKA stimulator Sp-cAMP reverts the effect of D1/D5 dopaminergic antagonist SCH 23390, but the infusion of PKC stimulator PMA does not. The results attest to the generality of the novelty effect on fear extinction, suggest that it relies on synaptic tagging and capture, and show that it depends on hippocampal dopamine D1 but not D5 receptors.

Memory deficits and oxidative stress in cerebral ischemia-reperfusion: neuroprotective role of physical exercise and green tea supplementation.

Ischemic stroke is a major cause of morbidity and mortality all over the world. Among impairments observed in survivors there is a significant cognitive learning and memory deficit. Neuroprotective strategies are being investigated to minimize such deficits after an ischemia event. Here we investigated the neuroprotective potential of physical exercise and green tea in an animal model of ischemia-reperfusion. Eighty male rats were divided in 8 groups and submitted to either transient brain ischemia-reperfusion or a sham surgery after 8 weeks of physical exercise and/or green tea supplementation. Ischemia-reperfusion was performed by bilateral occlusion of the common carotid arteries during 30 min. Later, their memory was evaluated in an aversive and in a non-aversive task, and hippocampus and prefrontal cortex were removed for biochemical analyses of possible oxidative stress effects. Ischemia-reperfusion impaired learning and memory. Reactive oxygen species were increased in the hippocampus and prefrontal cortex. Eight weeks of physical exercise and/or green tea supplementation before the ischemia-reperfusion event showed a neuroprotective effect; both treatments in separate or together reduced the cognitive deficits and were able to maintain the functional levels of antioxidant enzymes and glutathione.

Conhecendo o sistema nervoso: ações de divulgação e popularização da neurociência junto a estudantes da Rede Pública de Educação Básica / Knowing the nervous system: actions of neuroscience divulgation and popularization with students of Public Basic Education

Este estudo tem a finalidade de relatar uma prática proposta (Semana do Cérebro de Uruguaiana) com o intuito de contribuir com a popularização e divulgação da Neurociência junto à Educação Básica. Paralelamente à Semana Internacional do Cérebro (Brain Awareness Week) foram realizadas atividades voltadas para alunos da rede pública de Educação Básica. As atividades foram organizadas em seis etapas: (1) divulgação; (2) palestra explicativa sobre o funcionamento do Sistema Nervoso Central; (3) exposição de neuroanatomia; (4) demonstração prática de ações nervosas; (5) noções de pesquisa científica em neurociências; e (6) avaliação. Ao final verificou-se a opinião dos alunos quanto às atividades realizadas durante as diferentes etapas, 98,6% manifestaram ter interesse em aprender mais sobre o sistema nervoso, 85,2% relataram que as atividades propostas serviram para despertar seu interesse por pesquisa e ciência, e, ao avaliarem as ações de uma forma geral, atribuindo uma nota de 0 a 10, a nota atribuída foi de 9,4 ± 0,99. Desse modo, pode-se afirmar que a proposta foi bem aceita pelos alunos, sendo considerada válida e atingindo o objetivo de promover a divulgação e popularização da neurociência.

This study aimed to report a practice (Brain Awareness Week of Uruguaiana) that was proposed with the aim of contribute with the popularization and dissemination of Neuroscience in the Basic Education. Alongside the Brain Awareness Week we performed activities with students from public basic education. The activities were organized in six steps: (1) disclosure; (2) lecture explaining the functioning of the Central Nervous System; (3) neuroanatomy exposition; (4) practical demonstration of nerve actions; (5) notions of scientific research neuroscience; and (6) evaluation. At the end was verified the opinion of students about the activities carried in the different steps. 98.6% of students expressed interest in learning more about the nervous system. 85.2% reported that the activities proposed in our actions served to awaken their interest on research and science, and when evaluating the actions in general, with a score from 0 to 10, the assigned score was 9.4 ± 0.99. Thus, we can claim that our proposal was well accepted by the students and is considered valid and reaching the aim of promoting the dissemination and popularization of neuroscience.

Influence of mental practice and movement observation on motor memory, cognitive function and motor performance in the elderly / Influência da prática mental e observação do movimento sobre a memória motora, função cognitiva e desempenho motor em idosos

BACKGROUND: With aging, it is important to maintain cognitive and motor functions to ensure autonomy and quality of life. During the acquisition of motor skills, it is necessary for the elderly to understand the purpose of the proposed activities. Physical and mental practice, as well as demonstrations, are strategies used to learn movements. OBJECTIVES: To investigate the influence of mental practice and the observation of movement on motor memory and to understand the relationship between cognitive function and motor performance in the execution of a sequence of digital movements in the elderly. METHOD: This was a cross-sectional study conducted with 45 young and 45 aged subjects. The instruments used were Mini-Mental State Examination (MMSE), Manual Preference Inventory and a Digital Motor Task (composed of a training of a sequence of movements, an interval and a test phase). The subjects were divided into three subgroups: control, mental practice and observation of movement. RESULTS: The elderly depend more strongly on mental practice for the acquisition of a motor memory. In comparing the performances of people in different age groups, we found that in the elderly, there was a negative correlation between the MMSE score and the execution time as well as the number of errors in the motor task. CONCLUSIONS: For the elderly, mental practice can advantage motor performance. Also, there is a significant relationship between cognitive function, learning and the execution of new motor skills. .

CONTEXTUALIZAÇÃO: Com o envelhecimento, é importante a manutenção da função motora e cognitiva para garantir autonomia e qualidade de vida. Durante a aquisição de habilidades motoras é necessário que o idoso seja capaz de compreender o objetivo das atividades propostas e, para isso, a prática física e mental, assim como a demonstração, são estratégias usadas para o indivíduo aprender os movimentos. OBJETIVOS: Verificar a influência da prática mental e da observação do movimento sobre a memória motora e a relação entre a função cognitiva e o desempenho motor na execução de uma sequência de movimentos digitais em idosos. MÉTODO: Estudo transversal, realizado com 45 jovens e 45 idosos. Foram utilizados: Miniexame do Estado Mental (MEEM); Inventário de Preferência Manual de Edinburgh e Tarefa Motora Digital (composta por fase de treino, intervalo e teste). Os sujeitos foram divididos em três subgrupos: controle, prática mental e observação do movimento. RESULTADOS: Observou-se que idosos parecem depender mais da prática mental para a aquisição de uma memória motora e, na comparação do desempenho entre as faixas etárias, houve diferença no tempo de execução; nos idosos, observou-se correlação negativa entre o escore do MEEM e o tempo de execução e o número de erros na tarefa motora. CONCLUSÕES: Para idosos, a prática mental parece favorecer o desempenho motor, assim como existe uma relação significativa entre a função cognitiva e o aprendizado e execução de novas habilidades motoras. .