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Updated: Dec 10, 2025
Early Pathological and Magnetic Resonance Detection of Cerebral Injury Using a Rat Model of Neonatal Hypoxic Ischemic Encephalopathy
Published on: October 28, 2022
Microhemorrhage in a Rat Model of Neonatal Shaking Brain Injury: Correlation between MRI and Iron Histochemistry
Daisuke Taguchi1,2, Ayuka Ehara2, Yoshiteru Seo3
1Department of Judo Therapy, Faculty of Medical Technology, Teikyo University, Utsunomiya, Tochigi 320-8551, Japan.
Abstract:
Previous studies have shown that neonatal shaking brain injury (SBI) causes transient microhemorrhages (MHs) in the gray matter of the cerebral cortex and hippocampus. Iron deposits and iron-uptake cells are observed surrounding MHs in this SBI model, suggesting local hypoxic-ischemic conditions. However, whether the shaken pups suffered systemic hypoxic-ischemic conditions has remained uncertain. Further, histopathological correlations of MHs on magnetic resonance imaging (MRI) are still unclear. The present study examined MHs after neonatal SBI using a combination of histochemical and susceptibility-weighted imaging (SWI) analyses. Systemic oxygen saturation analyses indicated no significant difference between shaken and non-shaken pups. MHs on postnatal day 4 (P4) pups showed decreased signal intensity on SWI. Iron histochemistry revealed that these hypointense areas almost completely comprised red blood cells (RBCs). MHs that appeared on P4 gradually disappeared by P7-12 on SWI. These resolved areas contained small numbers of RBCs, numerous iron-positive cells, and punctate regions with iron reaction products. Perivascular iron products were evident after P12. These changes progressed faster in the hippocampus than in cortical areas. These changes in MHs following neonatal SBI may provide new insights into microvascular pathologies and impacts on brain functions as adults.
Insights
Neonatal shaking brain injury causes transient microhemorrhages, but not systemic hypoxia. These brain bleeds resolve over time, showing evolving iron deposits and cellular changes, offering insights into microvascular pathologies.
Area of Science:
- Neuroscience
- Developmental Biology
- Pathology
Background:
- Neonatal shaking brain injury (SBI) induces transient microhemorrhages (MHs) in the brain.
- Iron deposits suggest local hypoxic-ischemic conditions, but systemic effects remain unclear.
- Histopathological basis of MHs observed on MRI needs clarification.
Purpose of the Study:
- To investigate the nature and resolution of MHs following neonatal SBI.
- To correlate MRI findings of MHs with histochemical analyses.
- To determine if SBI causes systemic hypoxic-ischemic conditions.
Main Methods:
- Utilized a neonatal shaking brain injury (SBI) model in pups.
- Employed susceptibility-weighted imaging (SWI) for MH visualization.
- Conducted iron histochemistry to analyze cellular and iron deposition changes.
- Performed systemic oxygen saturation analysis.
Main Results:
- SBI did not cause significant systemic hypoxia.
- MHs on postnatal day 4 (P4) appeared as hypointense areas on SWI, primarily composed of red blood cells (RBCs).
- MHs resolved by P7-12, with residual RBCs, iron-positive cells, and iron products; perivascular iron appeared after P12.
- Resolution dynamics differed between hippocampus and cortex.
Conclusions:
- Neonatal SBI causes localized brain microhemorrhages, not systemic hypoxia.
- The study clarifies the histopathological evolution of MHs seen on SWI.
- Findings provide insights into microvascular changes and potential long-term brain function impacts.
