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The effect of hypothermia on transient middle cerebral artery occlusion in the rat
Abstract:
We investigated the effect of moderate whole body hypothermia (30 degrees C) on transient middle cerebral artery occlusion (MCAO) in the rat. Male Wistar rats were subjected to 2 h of ischemia by inserting a suture into the lumen of the internal carotid artery and occluding the origin of the MCA. Experimental groups were (a) MCAO induced at 37 degrees C body temperature (n = 15); (b) 30 degrees C body temperature induced prior to ischemia and maintained for 2 h of MCAO and 1 h of reperfusion (n = 12); and (c) MCAO with regional brain and body temperatures measured in normothermic (n = 3) and hypothermic MCAO rats (n = 2). Histopathological evaluation was performed 96 h after reperfusion. All normothermic MCAO animals exhibited ischemic infarct involving the ipsilateral cortex and basal ganglia with infiltration of neutrophils, macrophages, and microvascular proliferation. Hypothermic MCAO animals exhibited minor ischemic damage ranging from selective neuronal injury to small focal areas of infarct with minimal inflammatory response. Our data demonstrate that transient ischemia induced by using the intra-arterial suture method to occlude the MCA results in a reproducible brain lesion and that moderate hypothermia has a profound protective effect on the brain injury after transient MCAO.
Insights
Moderate whole body hypothermia significantly protects the brain from ischemic injury. Cooling rats to 30°C before and during middle cerebral artery occlusion reduced infarct size and inflammation.
Area of Science:
- Neuroscience
- Physiology
- Pathology
Background:
- Ischemic stroke, particularly middle cerebral artery occlusion (MCAO), causes significant brain damage.
- Inflammation and neuronal injury are key pathological features of ischemic stroke.
- Therapeutic hypothermia is being explored as a neuroprotective strategy.
Purpose of the Study:
- To investigate the neuroprotective effects of moderate whole body hypothermia (30°C) on transient middle cerebral artery occlusion (MCAO) in a rat model.
- To evaluate the impact of hypothermia on infarct size, neuronal damage, and inflammatory response following MCAO.
- To establish the efficacy of moderate hypothermia in mitigating brain injury after transient cerebral ischemia.
Main Methods:
- Male Wistar rats underwent 2 hours of transient MCAO using an intra-arterial suture method.
- Experimental groups included normothermic MCAO (37°C) and moderate hypothermic MCAO (30°C).
- Histopathological evaluation was conducted 96 hours post-reperfusion to assess infarct volume, neuronal injury, and inflammatory cell infiltration.
Main Results:
- Normothermic MCAO rats developed significant ischemic infarcts in the cortex and basal ganglia, accompanied by neutrophil and macrophage infiltration.
- Hypothermic MCAO rats exhibited markedly reduced ischemic damage, with only selective neuronal injury or small focal infarcts.
- The inflammatory response, including microvascular proliferation, was substantially diminished in hypothermic MCAO animals.
Conclusions:
- Transient MCAO induced by the intra-arterial suture method reliably reproduces brain lesions.
- Moderate whole body hypothermia demonstrates a profound protective effect against brain injury following transient MCAO.
- Therapeutic hypothermia is a promising strategy for reducing brain damage in ischemic stroke.