Densidad neuronal en la corteza visual primaria (área 17), en ratas sometidas a estrés crónico / Density in primary visual cortex (17 visual area) from rats subjected to chronic stress

El estrés puede ser definido como una amenaza a la integridad psicológica o fisiológica de un individuo. Por otro lado, se ha verificado que el estrés tiene efecto sobre la morfología y función de diversas estructuras del Sistema Nervioso Central, relacionadas con el aprendizaje, memoria y respuestas emocionales, tales como el hipocampo, amígdala y corteza prefrontal. Es por lo anterior, que el objetivo del presente trabajo fue realizar un estudio de la anatomía de la corteza visual primaria (área 17), en ratas machos (n=9), de la cepa Sprague-Dawley, de 3 meses de edad (250-350g.), sometidas a estrés crónico por inmovilización. Es así como se observó que el grupo estrés (n=3) presentó una menor densidad neuronal que el grupo control (n=3) y una significativa menor densidad neuronal (p<0,05) que el grupo post estrés (n=3) el cual presentó la más alta densidad neuronal observada. Estableciendo una relación inversa entre densidad neuronal y tamaño de los somas neuronales y sus respectivas conexiones y ramificaciones dendríticas. Lo anterior podría tener incidencia en el procesamiento de la información visual.

Stress can be understood as a threat to psychological or physiological integrity of the individual. Stress has previously shown to alter morphology and function of diverse structures of the Central Nervous System related to learning, memory and emotional response, such as hippocampus, amygdala and prefrontal cortex. In the current work we assessed the effect of chronic stress for immobilization on structure of primary visual cortex (area 17) in male adult Sprague-Dawley rats (n=9), of 3 months of age (250-350g.). Stressed rats (n=3) tended to show lower neuronal densities than control rats (n=3) and were significantly lower (p<0.05) than recovered post-stress rats (n=3), which showed the highest neuronal densities observed. Since an inverse correlation between neuronal density and size of neuronal bodies and their respective dendrite branches, these changes might impact processing of visual information.

Interactions of laminin with the amyloid ß peptide: Implications for Alzheimer's disease

Extensive neuronal cell loss is observed in Alzheimer's disease. Laminin immunoreactivity colocalizes with senile plaques, the characteristic extracellular histopathological lesions of Alzheimer brain, which consist of the amyloid ß (Aß) peptide polymerized into amyloid fibrils. These lesions have neurotoxic effects and have been proposed to be a main cause of neurodegeneration. In order to understand the pathological significance of the interaction between laminin and amyloid, we investigated the effect of laminin on amyloid structure and toxicity. We found that laminin interacts with the Aß1-40 peptide, blocking fibril formation and even inducing depolymerization of preformed fibrils. Protofilaments known to be intermediate species of Aß fibril formation were also detected as intermediate species of laminin-induced Aß fibril depolymerization. Moreover, laminin-amyloid interactions inhibited the toxic effects on rat primary hippocampal neurons. As a whole, our results indicate a putative anti-amyloidogenic role of laminin which may be of biological and therapeutic interest for controlling amyloidosis, such as those observed in cerebral angiopathy and Alzheimer's disease