A single systemic transient hypotension induces long-term changes in rats' MRI parameters and behavior: relation to...

Area of Science:

• Neuroscience
• Radiology
• Gerontology

Background:

• Systemic hypotension can affect brain function.
• Understanding the long-term consequences of transient hypotension is crucial.
• Cerebral aging may influence the brain's response to injury.

Purpose of the Study:

• To investigate short- and long-term brain changes in rats after a single 20-minute hypotension event.
• To assess the impact of hypotension on different age groups of rats (12 and 18 months old).
• To evaluate the utility of diffusion-weighted magnetic resonance imaging (DW-MRI) for longitudinal assessment.

Main Methods:

• Hemorrhagic hypotension was induced for 20 minutes in rats.
• Behavioral testing (holeboard) was performed to assess locomotor activity and memory.
• Diffusion-weighted magnetic resonance imaging (DW-MRI), T2, and T2* relaxometry were used for in vivo assessment over 6 months.

Main Results:

• Hypotension initially reduced apparent diffusion coefficient (ADC), increased T2 relaxation time, and impaired memory and activity.
• A transient pseudo-normalization was observed, but significant differences in ADC and T2 remained at 6 months.
• A negative correlation between T2 relaxation time and memory capacity was found.
• Older rats (18 months) showed more pronounced age-related changes in hippocampal ADC, T2/T2* relaxation times, and behavior.

Conclusions:

• A single, brief hypotension event can induce persistent long-term changes in the rat brain.
• Increased T2 relaxation time is associated with reduced memory capacity.
• DW-MRI is a valuable tool for longitudinal in vivo monitoring of brain changes after injury.
• Further research involving MRI perfusion and histology is needed to correlate imaging findings with structural brain changes.