[Investigation into the astrocytic immunoreactivity to GFAP and vimentin in the brainstem of Wistar rats submitted to the ethidium bromide gliotoxic model].

Ethidium bromide (EB) is known as a gliotoxic agent that causes focal astrocytic and oligodendroglial disappearance. Astrocyte immunoreactivity to glial fibrillary acidic protein (GFAP) and vimentin (VIM) was investigated after EB injection. Adult male Wistar rats were taken as histologic controls (group H) or injected into cisterna pontis with 0.1% EB (group E) or 0.9% saline solution (group C). Brainstem samples were collected from 24 hours to 31 days post-injection for GFAP and VIM immunohistochemical staining using avidin-biotin method. In group E, extensive lesions were seen in the pons and mesencephalon, with astrocyte disappearance from the central area 24 hours post-injection. Macrophagic infiltration and peripheral astrocytic reaction were noted after 3 days. Marginal astrocytes presented increased immunoreactivity to GFAP and reexpression of VIM, the last one confined to the edges of the injury site. In group C, discrete pontine lesions were observed, showing central astrocyte preservation and a peripheral GFAP staining less intense comparing to group E. No immunoreactivity to VIM was noted in such astrocytes. Astrocytes from the edges of the EB-induced lesions presented increased immunoreactivity to GFAP and reexpression of VIM.