Establishment of a rat model of severe spontaneous intracerebral hemorrhage

Background:Severe intracerebral hemorrhage(ICH)is the most devastating subtype of stroke resulting in high mortality and disability.At present,the development of targeted treatments to minimize the high morbidity and mortality is limited partly due to the lack of a severe ICH animal model.In this study,we aimed to establish an accurate severe ICH model in rats and examine the pathological and physiological changes associated with ICH.Methods:A rat model of severe ICH model was established by intrastriatal injection of autologous blood using different blood volumes(ICH 100μL group,ICH 130μL group,ICH 160μL group,ICH 170μL group,and ICH 180μL group).The mortality was assessed during the 28-day post-ICH period.Short-and long-term neurological deficits were evaluated using the Longa method,foot fault,falling latency,and Morris water maze tests.Brain water content,hematoma volume,hemoglobin content,and magnetic resonance imaging were assessed to determine the extent of brain injury.Immunofluorescence staining was conducted to examine microglial activation and neuronal apoptosis.Hematoxylin and eosin(H&E)staining,lung water content,and western blotting were used to assess lung injury following ICH.Results:The mortality of ICH rats increased significantly with an increase in autologous blood injection.The 28-day mortality in the 100μL,130μL,160μL,170μL,and 180μL ICH groups were 5%,20%,40%,75%,and 100%,respectively.A significantly higher 28-day mortality was observed in the ICH 160μL group compared to the ICH 100μL group.The ICH 160μL group exhibited significantly increased neurological deficits,brain edema,hematoma volume,and hemoglobin content compared to the sham group.Compared with the sham operation group,the activation of microglia and neuronal death in ICH 160μL rats increased.The use of H&E staining and western blotting demonstrated that disruption of the intra-alveolar structure,alveolar edema,and infiltration of inflammatory cells and cytokines into the lung tissue were more severe in the ICH 160μL group than the sham group.Conclusions:A severe ICH model in rats was successfully established using an injection of autologous blood at a volume of 160μL.This model may provide a valuable tool to examine the pathological mechanisms and potential therapeutic interventions of severe ICH.