Navegando por Palavras-chave "Interneurons"

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    Distribuição da proteína IMPACT em encéfalos de camundongos, ratos e sagüis
    (Universidade Federal de São Paulo (UNIFESP), 2009-11-26) Bittencourt, Simone [UNIFESP]; Mello, Luiz Eugenio Araujo de Moraes [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The control of protein synthesis plays a major role in several physiological conditions, homeostatic mechanisms and several phenomenon of neuronal plasticity. One of the most important mechanisms in regulation of protein synthesis is the phosphorylation of the initiation factor 2 (eIF2α). Increase in the eIF2α phosphorylation blocks general translation and enhance translation of specific genes such ATF4 (activating transcription factor 4) for example. In response to specific stress stimuli four specific kinases can phosphorylate eIF2α. The GCN2 kinase, for instance, is abundant in the brain, and is involved in feeding behavior control, learning and memory of mammalians. The IMPACT protein, preferentially expressed in the brain, acts as an inhibitor of the activation of GCN2. Therefore, a systematic analysis of the distribution of IMPACT in the brain and its possible involvement in physiological and/or pathological conditions are relevant. The following results were observed: (i) The IMPACT protein is preferentially expressed in brain nuclei involved in circadian rhythms, as well as in important nuclei involved in rhythm generation, such as the hippocampal theta rhythm; (ii) The high density and intensity of IMPACT labeling in the hypothalamus and hippocampus may reflect its involvement in homeostatic mechanisms (hypothalamic function) and memory (hippocampal function). (iii) In adult tissue, only a few neuronal groups showed divergence in IMPACT expression between rodents and primate; (iv) Within a single species there was differential expression of IMPACT in specific neuronal groups (e.g. GABAergic neurons); (v) IMPACT-positive neurons were resistant to several types of stress (weak, strong, acute or chronic), such as low temperature and status epilepticus induced by pilocarpine in a model of epilepsy; (vi) IMPACT is a constitutive protein, insensitive to perturbations in vivo; (vii) The detection of IMPACT starts at E16 embryonic stage. According to these results on the neurons expressing IMPACT and the evidence of its presence in some brain areas, we speculate on its possible relevance in neurophysiology. Thus, these data taken together suggest that IMPACT-positive neurons have important functions in the mammalian brains and may be involved in generation and control of brain rhythms and physiological homeostasis in general.