RESUMO
Sustained stress can have numerous pathologic effects. There have been several animal models for chronic stress. We tried to identify the changes of pain threshold and hippocampus in a model of chronic stress. Male Sprague-Dawley rats were kept in a cage filled with 23°C water to a height of 2.2 cm for 7 days. Nociceptive thresholds, expressed in grams, were measured with a Dynamic Plantar Aesthesiometer. Golgi staining was used to identify hippocampal changes. To demonstrate how long allodynia was lasting, behavioral test was repeated daily on another experiment. Compared to control group, chronic stress group showed bilateral mechanical hyper-responsiveness on days 5 (P = 0.047) and 7 (P = 0.032). In general, dendrite atrophic changes within hippocampus of chronic stress model were much more prominent in comparison with control. Compared to control, decreased spine number (P < 0.001) and spine length (P < 0.001) on Golgi staining were seen in the hippocampus of animals with chronic stress. Bilateral mechanical hyperresponsiveness was recovered on day 19 in animals with chronic stress. Chronic stress may bring about central sensitization and hippocampal changes in rats.
Assuntos
Hipocampo/patologia , Hiperalgesia/patologia , Animais , Comportamento Animal , Modelos Animais de Doenças , Masculino , Limiar da Dor , Ratos , Ratos Sprague-Dawley , Estresse FisiológicoRESUMO
Long-term synaptic plasticity requires addition of new proteins at the synaptic site. The local protein synthesis at subsynaptic sites confers advantageous mechanisms that would regulate the protein composition in local domains on a moment-by-moment basis. However, our information on the identities of 'dendritic' mRNAs is very limited. In this study we investigated the expression of the protein and mRNA for eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4EBP1) in cultured rat hippocampal neurons. Immunocytochemistry (ICC) showed that 4EBP1 protein is highly localized to the nucleus. In dendrites most 4EBP1 punctae were not colocalized with those of eIF4E. In situ hybridization (ISH) and Fluorescence ISH (FISH) revealed that 4EBP1 mRNA was present in dendrites. The FISH signals formed clusters along dendrites that colocalized with ICC signals for Staufen, a marker for RNA granules. The neuronal activation by KCl (60 mM, 10 min) significantly increased the density of 4EBP1 FISH signals in the nucleus after 2 hr, and both in the nucleus and dendrites after 6 hr. Our results indicate that 4EBP1 and its mRNA are present in dendrites, and the mRNA is upregulated and transported to dendritic domains in RNA granules upon neuronal activation.
Assuntos
Proteínas de Transporte/metabolismo , Dendritos/metabolismo , Hipocampo/metabolismo , Fosfoproteínas/metabolismo , RNA Mensageiro/metabolismo , Animais , Proteínas de Transporte/genética , Núcleo Celular/metabolismo , Células Cultivadas , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Peptídeos e Proteínas de Sinalização Intracelular , Fosfoproteínas/genética , Cloreto de Potássio/farmacologia , Proteínas de Ligação a RNA/metabolismo , Ratos , Ratos Sprague-Dawley , Regulação para Cima/efeitos dos fármacosRESUMO
This study examined a 55 kDa protein in the rat cerebellar postsynaptic density (PSD) fraction. The amino acid sequence of an HPLC-purified peptide derived from tryptic digestion of the protein was contained in eukaryotic translation elongation factor-1A (eEF1A, formerly known as eEF-1alpha). Immunoblot analysis showed that eEF1A is enriched in the PSD fraction and is tightly associated with the PSD 'core'. The association of eEF1A with the PSD was further evidenced by colocalization of the protein with PSD95, a PSD marker, in dissociated cerebellar cultures and immunoelectron microscopy of the adult rat cerebellum. Combined, our results indicate that eEF1A is associated with the PSD.
