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Updated: Mar 14, 2026
Early Pathological and Magnetic Resonance Detection of Cerebral Injury Using a Rat Model of Neonatal Hypoxic Ischemic Encephalopathy
Published on: October 28, 2022
Combined damage produced by multiple mild cerebral insults assessed using MRI in neonatal rats
Ursula I Tuor1, Manasi Sule1, Min Qiao1
1Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, 3280 Hospital Dr, NW, Calgary, T2N 2T8, Canada.
Purpose:
To determine whether damage to neonatal brain is exacerbated with multiple mild cerebral insults as detected with MRI and corroborated using histology.
Materials And Methods:
The combined brain injury produced by multiple procedures was compared in neonatal rats having: Sham surgery at P5, Sham surgery at P5 plus a diffuse mild transient unilateral cerebral hypoxia ischemia (HI) at P7, HI alone, and a minor photothrombotic (PT) stroke at P5 followed by HI. MRI after the ischemic insults was followed by final histology.
Results:
PT produced lesions with increased T2 and decreased apparent diffusion coefficient for water (ADC) but no significant effects of a second HI. However, near the PT lesion/parietal cortex there were patchy areas of enhanced T2 and decreased ADC in 6/9, 3/8 and 0/8 animals in the PT+HI, Sham+HI and HI groups, respectively (P<0.05). Patches corresponded histologically to increased vacuolation and cell death and were more pronounced in the PT+HI and Sham+PT groups than the HI group.
Conclusion:
The extent of damage produced by a minor neonatal stroke followed by a diffuse HI two days later results in heterogeneous enhancement of T2, ADC and histological injury near the lesion. Surgical procedures including mechanical head manipulation followed by HI also produced some enhanced heterogeneity of hypoxic-ischemic injury affirming the need for sham controls.
Insights
Multiple mild brain injuries in neonatal rats can worsen damage, especially when a minor stroke is followed by hypoxia-ischemia. This study used MRI and histology to detect and confirm brain injury.
Area of Science:
- Neonatal neurology
- Neuroimaging
- Cerebral injury models
Background:
- Neonatal brain injury is a significant concern.
- Understanding the cumulative effects of multiple insults is crucial for developing effective treatments.
- Magnetic Resonance Imaging (MRI) and histology are key tools for assessing brain damage.
Purpose of the Study:
- To investigate if multiple mild cerebral insults exacerbate neonatal brain damage.
- To detect and corroborate brain injury using MRI and histology.
- To evaluate the combined effects of photothrombotic stroke and hypoxia-ischemia.
Main Methods:
- Neonatal rats underwent procedures including sham surgery, hypoxia-ischemia (HI), photothrombotic (PT) stroke, or combinations thereof.
- MRI was used to assess brain injury after ischemic insults.
- Histology was performed to corroborate MRI findings and evaluate cellular damage.
Main Results:
- A minor PT stroke followed by HI showed increased T2 and decreased ADC near the lesion.
- Patchy areas of enhanced T2 and decreased ADC were observed in PT+HI and Sham+PT groups, indicating increased injury.
- Histology confirmed vacuolation and cell death in these areas, more pronounced with combined insults.
Conclusions:
- A minor neonatal stroke followed by hypoxia-ischemia leads to heterogeneous brain injury.
- Surgical procedures and subsequent HI can enhance injury heterogeneity.
- The use of appropriate sham controls is essential in studies involving multiple insults.
