Rat Brainstem Hemorrhage Model: Key Points to Success in Modeling

Abstract

A successful animal brainstem hemorrhage model can be used to study pathophysiology and molecular mechanisms of neurologic deterioration or recovery and therapeutic interventions after the brainstem hemorrhage. Herein, we provide a reproducible and reliable model for rat brainstem hemorrhage and summarize our key points to success in modeling. Twenty-four adult male Sprague-Dawley rats were divided into 3 groups and were injected with 30, 40, and 60 μL autologous blood into the right pontine basal tegmentum after being sedated. The initial model was evaluated with neurobehavior testing, autopsy, and histopathology. The modeling conditions were modified in Group IV rats, and 20 more rats were used to check the reproducibility and reliability of the modified model. Finally, magnetic resonance imaging (MRI) was used to confirm the brainstem hemorrhage. Only 6 rats had significant pontine hemorrhage in initial 3 groups on autopsy. Whereas after the modification, all Group IV rats had serious pontine hemorrhage, and modified conditions model had a 90% success rate. MRI confirmed a stable hematoma in the right basal tegmental pons with oval shape 24 hours after of blood injection. Histopathologically, there was significant perihematomal swelling, migration of inflammatory cells and structural changes in neuronal shape and contents. An ideal and repeatable rat brainstem hemorrhage model by injecting autologous blood stereotactically was created, and it mimics the natural onset of brainstem hemorrhage. This brainstem hemorrhage model shows promise that providing a better way for neurology researchers to investigate pathophysiologic procedure of brainstem intracranial hemorrhage and further explore the treatment.