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Recirculation model following MCA occlusion in rats. Cerebral blood flow, cerebrovascular permeability, and brain
Abstract:
A new model for establishing a successful and consistent arterial recirculation has been devised following middle cerebral artery (MCA) occlusion in the rat. A snare ligature was introduced at the stem of the MCA just distal to the lenticulostriate branches, and occlusion and recirculation were performed by pulling and releasing the thread. This method had an advantage over the use of a small clip which caused damage to the artery without good recirculation. Study of local cerebral blood flow using carbon-14 (14C)-iodoantipyrine, of cerebrovascular permeability using 14C-aminoisobutyric acid, and of brain-water content using the microgravimetric technique was performed upon recirculation following various periods of occlusion and compared with the results in permanent ischemia. A reactive hyperemia was noted within the previously ischemic area immediately upon recirculation following either a 30-minute or a 2-hour ischemic period. One or 2 hours later, delayed hypoperfusion developed in this region, but the circulation over the periphery of the ischemic area recovered well. Cerebrovascular permeability was not, however, altered during the time courses studied. Topographic changes in tissue specific gravity were compared between permanent and transient ischemia in the corresponding time-courses. Although there was a greater decrease in tissue specific gravity following recirculation when the ischemic period was maintained longer, edema formation was resolved by recirculation. Further study is required to determine thresholds of ischemic brain damage and edema formation at recirculation following focal cerebral ischemia.
Insights
A novel rat model for middle cerebral artery (MCA) occlusion and recirculation was developed. This method allows for consistent arterial recirculation, aiding stroke research by examining blood flow and edema formation.
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Ischemic Stroke Models
Background:
- Establishing consistent arterial recirculation after focal cerebral ischemia is crucial for stroke research.
- Previous methods using clips for middle cerebral artery (MCA) occlusion caused arterial damage and inconsistent recirculation.
- A new snare ligature technique offers improved control over occlusion and recirculation in a rat model.
Purpose of the Study:
- To develop and validate a new model for reproducible middle cerebral artery (MCA) occlusion and recirculation in rats.
- To investigate the effects of transient focal cerebral ischemia on local cerebral blood flow, cerebrovascular permeability, and brain-water content.
- To compare outcomes of transient ischemia with permanent ischemia regarding tissue-specific gravity and edema formation.
Main Methods:
- A snare ligature was used for precise middle cerebral artery (MCA) occlusion and release in rats.
- Local cerebral blood flow was measured using 14C-iodoantipyrine.
- Cerebrovascular permeability was assessed with 14C-aminoisobutyric acid, and brain-water content was determined by microgravimetry.
Main Results:
- Reactive hyperemia was observed immediately upon recirculation after 30-minute or 2-hour MCA occlusion.
- Delayed hypoperfusion occurred in the ischemic area 1-2 hours post-recirculation, while the periphery showed good recovery.
- Cerebrovascular permeability remained unchanged; however, edema formation was resolved by recirculation, though more pronounced with longer ischemia durations.
Conclusions:
- The new snare ligature model provides consistent arterial recirculation for studying focal cerebral ischemia.
- Transient MCA occlusion leads to initial hyperemia followed by delayed hypoperfusion and resolved edema.
- Further research is needed to define thresholds for ischemic brain damage and edema during recirculation after focal cerebral ischemia.