TIME-COURSE OF BLOOD BRAIN BARRIER DISRUPTION IN A RAT MODEL OF INTRACEREBRAL HEMORRHAGE BY MRI

Acute intracerebral hemorrhage (ICH) is the deadliest and most disabling form of stroke. After the initial bleeding, tissue disruption and edema contribute to secondary injury in the perilesional area. Blood–brain barrier (BBB) disruption is a key mechanism involved in this process; however, its temporal profile remains poorly characterized in preclinical rat models of ICH. The aim of this study was to describe the time course of BBB disruption in a rat model of ICH induced by autologous blood injection. Autologous blood was injected into the striatum of adult male and female Sprague–Dawley rats. T1-weighted magnetic resonance images were acquired using a Bruker BioSpec 70/30 small-animal scanner at 2 h, 24 h, and 3, 7, and 21 days post-injury (dpi), before and after subcutaneous administration of a gadolinium[SL1] -based contrast agent. Gadolinium-enhanced images revealed hyperintensity in the lesion core and perilesional area, which progressively increased from 24 h to 7 dpi, followed by a significant decrease at 21 dpi. To confirm the peak of BBB disruption, an independent group of animals received an intravenous injection of Evans blue (EB) at 7 dpi. After intracardiac perfusion, EB fluorescence was analyzed in brain sections, showing increased tracer extravasation in the perilesional area. Together, these findings indicate that BBB disruption is a delayed and dynamic event following ICH, occurring after the development of brain edema in the autologous blood injection rat model.