A rat model of oligomeric forms of beta-amyloid (Aß) peptide: neuronal loss, synaptic alteration, astrogliosis, and calcium-binding proteins activation in vivo

• Autores: Alicia Gonzalo Ruiz, Maria Delso, Isabel Carrero Ayuso, Pilar Gonzalo Vicente, José Miguel Sanz Anquela, Manuel J. Rodríguez, Juan Arévalo Serrano
• Localización: European Journal of anatomy, ISSN-e 1136-4890, Vol. 15, Nº. 1, 2011, págs. 47-72
• Idioma: inglés
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• Resumen

  • Oligomers of Beta-amyloid (Aß) peptide are presumed to cause synaptic and cognitive dysfunction in Alzheimer’s disease (AD). However, their contribution to other pathological features of AD remains unclear. To address the latter, we applied microinjections of Aß1-42 oligomers into the retrosplenial cortex of the rat. We observed that Aß1-42 induced a greater reduction in neuronal density as compared with that seen at control (Aß42-1) injections. Oligomers of Aß1-42 peptide caused synaptic alterations, as evidenced by the decrease in the presynaptic marker synaptophysin and the increase in chromogranin A. We also detected a marked interaction between GFAP-, and Aßimmunoreactive material in a time-dependent manner. To address the possible mechanisms involved in astrocyte activation, we analyzed the interaction between the calcium-dependent protease, calpain-1, and the calcium-binding protein, S100B, and astrogliosis in response to Aß toxicity. Calpain-1 activation was studied by immunoblotting. Three immunopositive protein bands (80kDa, 76kDa, and 18kDa) were detected. Densitometry analyses revealed a significant increase in calpain-1 at 76kDa and at position 18kDa in Aß1-42-treated animals as compared with the corresponding bands in control animals. Confocal analysis showed codistribution of Aß-, and calpain 1-immunoreactivities in cortical cells, and in reactive astrocytes surrounding the injection of Aß, and both cortical and leptomeningeal blood vessels. A colocalization of GFAP and S100B proteins was observed in astrocytes that surrounded the Aß injection, and also in reactive astrocytes in close association with blood vessels. In conclusion, our results suggest that calpain-1 and S100B might play a critical role in astroglisois in response to Aß toxicity.