Neurônio especial controla a chegada de informação do ambiente ao centro cerebral em que se formam as recordações.
Um grupo de pesquisadores do Brasil, dos Estados Unidos e da Suécia identificou a função de um tipo especial de célula cerebral que havia sido descrito quase um século atrás pelo médico espanhol Santiago Ramón y Cajal. Essas células, que recebem o nome complicado de neurônios oriens lacunosum-moleculare (OLM), estão no hipocampo, estrutura profunda do cérebro associada à aquisição da memória. Como uma ponte que une as duas margens de um rio, os neurônio OLM colocam as células da camada mais superficial do hipocampo em contato com as das áreas mais profundas. Mas nesse tempo todo o papel dessas células permanecia obscuro. Agora, em um artigo publicado na edição de 7 de outubro da revista Nature Neuroscience, o neurocientista mineiro Richardson Leão demonstrou que os neurônios OLM são uma espécie de porteiro da memória.
Quer saber mais, acesse: http://revistapesquisa.fapesp.br/2012/10/09/o-porteiro-da-memória/
Curso de Bacharelado em Educação Física do Centro Acadêmico de Vitória da Universidade Federal de Pernambuco
quarta-feira, 10 de outubro de 2012
sábado, 6 de outubro de 2012
Aumente o poder do cérebro com exercícios
Reportagem na IstoE N° Edição: 2237
Pesquisas revelam que a atividade física melhora concentração, memória, aprendizagem e estimula o nascimento de neurônios.
Não é segredo que a atividade física produz inúmeros benefícios para o corpo, mas agora a ciência reuniu provas suficientes para adicionar um novo e poderoso efeito à sua lista de ações positivas: o aprimoramento do cérebro. As mais recentes descobertas indicam que a prática regular de exercícios ajuda a pensar com mais clareza, melhora a memória e proporciona um grande ganho na aprendizagem. Novos estudos sugerem que as mudanças podem ser ainda maiores, alterando a própria estrutura do órgão ao incentivar o nascimento e o desenvolvimento de neurônios.
Essas conclusões são de uma ampla revisão de pesquisas que acaba de ser divulgada nos Estados Unidos por uma das mais renomadas cientistas no campo da neurogênese, Henriette van Praag (Ph.D), do Laboratório de Neurociências do Instituto Nacional de Saúde dos Estados Unidos. Henriette e seus colaboradores afirmam que há maior produção de neurônios e um aumento das substâncias que atuam na nutrição e desenvolvimento dessas células em animais submetidos a exercícios regulares. O trabalho foi publicado pela revista “Current Topics in Behavioral Neurosciences”. A cientista detectou ainda que o exercício aumenta a capacidade do cérebro de se adaptar e criar novas conexões, a chamada neuroplasticidade. Em estudos com ressonância magnética feitos em indivíduos foi possível também observar que quem se exercita regularmente produz uma intensa atividade no hipocampo. Essa região cerebral está relacionada à memória e à aprendizagem, e lá estão armazenadas as células-tronco que darão origem aos novos neurônios.
Exercicio de resistencia melhora a memoria!!
Resistance exercise improves hippocampus-dependent memory. Braz J Med Biol Res provisional Epub Aug 30, 2012
It has been demonstrated that resistance exercise improves cognitive functions in humans. Thus, an animal model that mimics this phenomenon can be an important tool for studying the underlying neurophysiological mechanisms. Here, we tested if an animal model for resistance exercise was able to improve the performance in a hippocampus-dependent memory task. In addition, we also evaluated the level of insulin-like growth factor 1/insulin growth factor receptor (IGF-1/IGF-1R), which plays pleiotropic roles in the nervous system. Adult male Wistar rats were divided into three groups (N = 10 for each group): control, SHAM, and resistance exercise (RES). The RES group was submitted to 8 weeks of progressive resistance exercise in a vertical ladder apparatus, while the SHAM group was left in the same apparatus without exercising. Analysis of a cross-sectional area of the flexor digitorum longus muscle indicated that this training period was sufficient to cause muscle fiber hypertrophy. In a step-through passive avoidance task (PA), the RES group presented a longer latency than the other groups on the test day. We also observed an increase of 43 and 94% for systemic and hippocampal IGF-1 concentration, respectively, in the RES group compared to the others. A positive correlation was established between PA performance and systemic IGF-1 (r = 0.46, P < 0.05). Taken together, our data indicate that resistance exercise improves the hippocampus-dependent memory task with a concomitant increase of IGF-1 level in the rat model. This model can be further explored to better understand the effects of resistance exercise on brain functions.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012007500138&lng=en&nrm=iso&tlng=en
It has been demonstrated that resistance exercise improves cognitive functions in humans. Thus, an animal model that mimics this phenomenon can be an important tool for studying the underlying neurophysiological mechanisms. Here, we tested if an animal model for resistance exercise was able to improve the performance in a hippocampus-dependent memory task. In addition, we also evaluated the level of insulin-like growth factor 1/insulin growth factor receptor (IGF-1/IGF-1R), which plays pleiotropic roles in the nervous system. Adult male Wistar rats were divided into three groups (N = 10 for each group): control, SHAM, and resistance exercise (RES). The RES group was submitted to 8 weeks of progressive resistance exercise in a vertical ladder apparatus, while the SHAM group was left in the same apparatus without exercising. Analysis of a cross-sectional area of the flexor digitorum longus muscle indicated that this training period was sufficient to cause muscle fiber hypertrophy. In a step-through passive avoidance task (PA), the RES group presented a longer latency than the other groups on the test day. We also observed an increase of 43 and 94% for systemic and hippocampal IGF-1 concentration, respectively, in the RES group compared to the others. A positive correlation was established between PA performance and systemic IGF-1 (r = 0.46, P < 0.05). Taken together, our data indicate that resistance exercise improves the hippocampus-dependent memory task with a concomitant increase of IGF-1 level in the rat model. This model can be further explored to better understand the effects of resistance exercise on brain functions.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012007500138&lng=en&nrm=iso&tlng=en
segunda-feira, 24 de setembro de 2012
quinta-feira, 20 de setembro de 2012
Protein turnover, amino acid requirements and recommendations for athletes and active populations
POORTMANS, J.R.; CARPENTIER, A.; PEREIRA-LANCHA, L.O. e LANCHA JR., A.. Protein turnover, amino acid requirements and recommendations for athletes and active populations. Braz J Med Biol Res [online]. 2012, vol.45, n.10, pp. 875-890. Epub 06-Jun-2012 ISSN 1414-431X. http://dx.doi.org/10.1590/S0100-879X2012007500096.
Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine,15N-glycine, 2H5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg-1·day-1 compared to 0.8 g·kg-1·day-1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0100-879X2012001000001&lng=pt&nrm=iso&tlng=en
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