Excitotoxicity can lead to increases in intracellular Na+ and Ca2+ concentrations via the glutamatergic NMDA receptors, which can lead to cell death. Detailing the time-dependent degradation of neuronal components in response to excitotoxic challenge may help elucidate the sequence in which these signaling pathways are initiated and further, associate these pathways with topographic cellular demise. Using organotypic hippocampal slice culture technique, tissue from neonatal rat pups was exposed to NMDA, APV, or co-exposed for 24, 72 or 120 hours. Fluorescent microscopy of propidium iodide (PI) was used to evaluate neuronal membrane damage, changes in the density of mature soma (NeuN) and NMDA NR2B subunits were measured using immunohistochemical procedures. After 24 hours of exposure, the CA1 showed an increased PI signal and a decrease in NeuN marker, indicating somatic injury occurs shortly after excitotoxic challenge; these effects were blocked by co-administration of APV. Also in the CA1, loss of NR2B subunits, heavily expressed in dendritic processes, declined following 72 hours of exposure. Because somatic injury precedes loss of distal NR2B subunits, it is possible that these events involve different mechanisms, findings that may be relevant in the development of therapies to target neurodegeneration resulting from excitotoxicity.

El objetivo de esta Tesis ha sido profundizar en el estudio del desarrollo del complejo claustroamigdalino en ratón. Para ello hemos estudiado: 1) cuales de sus componentes derivan del palio lateral o ventral, en base a expresión diferencial de genes reguladores Dbx1, Lhx9, Lhx2, Lmo3, Lmo4, Cadherina 8 y Emx1 durante el desarrollo embrionario; 2) el desarrollo de las interneuronas del complejo claustroamigdalino que contienen proteínas ligadoras de calcio (incluyendo el desarrollo de sus circuitos locales); 3) el origen histogenético de dichas interneuronas, mediante cultivos organotípicos y el análisis del ratón transgénico Nkx2.1-Cre/Rosa26-GFP (Kessaris y col. 2006). Nuestros datos permiten distinguir los componentes paliales laterales o ventrales del complejo, que contienen múltiples subtipos de interneuronas con orígenes en distintas subdivisiones del subpalio. Esto abre las puertas a futuras investigaciones sobre la conectividad y función de cada subtipo de interneurona, y sobre su grado de implicación en los desórdenes neuropsiquiátricos. / The objective of this Doctoral Thesis was to deepen in the study of the development of the claustroamygdaloid complex in mouse. For that, we pursued to study: 1) which components derive from either the lateral or ventral pallium based on differential expression of regulatory genes (Dbx1, Lhx9, Lhx2, Lmo3, Lmo4, Cadherina 8 y Emx1) during embryonic development; 2) the development of interneurons of the claustroamygdaloid complex that contain calcium binding proteins (including the development of its local circuits); 3) the histogenetic origin of these interneurons, by means of organotypic cultures and analysis of the transgenic mouse Nkx2.1-Cre/Rosa26-GFP (Kessaris and col. 2006). Our data allowed the distinction between lateral and ventral pallial components of the complex, which contain multiple subtypes of interneurons with origins in different subpallial subdivisions. This opens new venues for future investigations on the connectivity and function of each interneuron subtype, and on their involvement in neuropsychiatric disorders.