Selective ablation of astrocytes by intracerebral injections of alpha-aminoadipate.

The efficacy and the specificity of the putative astrotoxin, alpha-aminoadipate, were examined in this study. The integrity of astrocytes was evaluated at several time points following a single injection of alpha-aminoadipate into amygdala of adult rats using immunohistochemistry. The density and the morphological appearance of neurons and the response of microglia were also examined. The injection of alpha-aminoadipate disrupted the astrocytic network in that region. There was a profound loss of glial fibrillary acidic protein-positive and S100 beta-positive astrocytes, normally present in the region, while vimentin immunohistochemistry revealed the presence of deformed cell processes, presumably astrocytic. The presence of reactive microglia at the injection site was suggestive of an active degenerative process, while the normal neuronal density and appearance, as compared to controls, suggested that the damage was confined to astrocytes. The confirmed effectiveness and cellular specificity of alpha-aminoadipate in vivo makes it a potentially important experimental tool for attempting to decipher the functional significance of astrocytes.