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Updated: May 5, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
mRNA redistribution during permanent focal cerebral ischemia
Monique K Lewis1, Jill T Jamison, Joseph C Dunbar
1Department of Physiology, Wayne State University School of Medicine, 4116 Scott Hall, 540 East Canfield Ave, Detroit, MI, 48201, USA.
Abstract:
Translation arrest occurs in neurons following focal cerebral ischemia and is irreversible in penumbral neurons destined to die. Following global cerebral ischemia, mRNA is sequestered away from 40S ribosomal subunits as mRNA granules, precluding translation. Here, we investigated mRNA granule formation using fluorescence in situ histochemistry out to 8 h permanent focal cerebral ischemia using middle cerebral artery occlusion in Long Evans rats with and without diabetes. Neuronal mRNA granules colocalized with PABP, HuR, and NeuN, but not 40S or 60S ribosomal subunits, or organelle markers. The volume of brain with mRNA granule-containing neurons decreased exponentially with ischemia duration, and was zero after 8 h permanent focal cerebral ischemia or any duration of ischemia in diabetic rats. These results show that neuronal mRNA granule response has a limited range of insult intensity over which it is expressed. Identifying the limits of effective neuronal stress response to ischemia will be important for developing effective stroke therapies.
Insights
Neuronal mRNA granules form during focal cerebral ischemia but this stress response is limited, disappearing with longer ischemia or in diabetic rats, hindering stroke therapy development.
Area of Science:
- Neuroscience
- Molecular Biology
- Ischemic Stroke Research
Background:
- Translation arrest is a key neuronal response to cerebral ischemia.
- mRNA granules sequester mRNA, preventing translation during global ischemia.
- The limits of this stress response in focal ischemia are not well understood.
Purpose of the Study:
- To investigate neuronal mRNA granule formation in focal cerebral ischemia.
- To determine the duration and conditions under which mRNA granules form.
- To assess the impact of diabetes on this cellular response.
Main Methods:
- Utilized fluorescence in situ histochemistry in Long Evans rats.
- Induced permanent focal cerebral ischemia via middle cerebral artery occlusion.
- Examined mRNA granule colocalization with specific neuronal and ribosomal markers.
Main Results:
- Neuronal mRNA granules colocalized with PABP, HuR, and NeuN, but not ribosomal subunits.
- The extent of brain tissue with mRNA granules decreased exponentially with ischemia duration.
- mRNA granule formation was absent in diabetic rats and after 8 hours of ischemia.
Conclusions:
- Neuronal mRNA granule formation is a transient stress response with limited effectiveness.
- The response is highly sensitive to ischemia duration and metabolic state (diabetes).
- Understanding these limits is crucial for developing targeted stroke therapies.
