Ethidium bromide (EB) causes local astrocytic disappearance, with glia limitans disruption and blood-brain barrier (BBB) breakdown. The aim of this study was to evaluate the BBB integrity after the injection of 0.1% EB or 0.9% saline solution into the cisterna pontis of Wistar rats submitted or not to the streptozotocin diabetogenic model. Brainstem sections were collected from 24 hours to 31 days post-injection for ultrastructural analysis and glial fibrillary acidic protein immunohistochemical staining. Some animals received colloidal carbon ink by intravenous route at the same periods. In rats injected with EB, results revealed astrocyte disappearance and leakage of carbon particles beginning at 48 hours and persisting for 7 days in non-diabetic rats and for 15 days in the diabetic ones, although, in both groups, several areas remained devoid of astrocytic processes up to 31 days. In rats injected with saline, there was no sign of astrocytic loss or carbon particles leakage.