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Microembolism induces anhedonia but no detectable changes in white matter integrity in aged rats
Christina L Nemeth1, David A Gutman2, Waqas Majeed3
1Department of Psychiatry and Behavioral Science, Emory University, Atlanta, Georgia, United States of America; Department of Physiology, Emory University, Atlanta, Georgia, United States of America.
Abstract:
Microvascular disease leads to alterations of cerebral vasculature including the formation of microembolic (ME) strokes. Though ME are associated with changes in mood and the severity and progression of cognitive decline, the effect of ME strokes on cerebral microstructure and its relationship to behavioral endpoints is unknown. Here, we used adult and aged male rats to test the hypotheses that ME lesions result in subtle changes to white and gray matter integrity as detected by high-throughput diffusion tensor imaging (DTI) and that these structural disruptions correspond to behavioral deficits. Two weeks post-surgery, aged animals showed depressive-like behaviors in the sucrose consumption test in the absence of altered cerebral diffusivity as assessed by ex-vivo DTI. Furthermore, DTI indices did not correlate with the degree of behavioral disruption in aged animals or in a subset of animals with observed tissue cavitation and subtle DTI alterations. Together, data suggest that behavioral deficits are not the result of damage to brain regions or white matter tracts, rather the activity of other systems may underlie functional disruption and recovery.
Insights
Microembolic strokes may not directly damage brain microstructure, despite causing behavioral changes. Further research is needed to understand the underlying mechanisms of functional disruption and recovery in microembolic stroke.
Area of Science:
- Neuroscience
- Neurology
- Vascular Biology
Background:
- Microvascular disease can cause microembolic (ME) strokes, impacting mood and cognition.
- The precise effects of ME strokes on cerebral microstructure and their link to behavioral outcomes remain unclear.
Purpose of the Study:
- To investigate if ME lesions alter white and gray matter integrity using diffusion tensor imaging (DTI).
- To determine if structural brain changes correlate with behavioral deficits in adult and aged rats.
Main Methods:
- Adult and aged male rats underwent surgery to induce ME strokes.
- Ex-vivo DTI was used to assess cerebral microstructure integrity.
- Behavioral tests, including the sucrose consumption test, were performed.
Main Results:
- Aged rats exhibited depressive-like behaviors two weeks post-surgery.
- No significant alterations in cerebral diffusivity were detected by DTI in aged animals.
- DTI indices did not correlate with behavioral deficits or observed tissue cavitation.
Conclusions:
- Behavioral deficits following ME strokes may not stem from direct damage to brain regions or white matter tracts.
- The activity of other systems likely underlies functional disruption and recovery after ME strokes.
