[Comparison of neuroprotective effects of hypothermia induced by different methods in rats with early cerebral ischemia].

OBJECTIVE: To compare the neuroprotective effects of intracarotid cold saline infusion (ICSI), ice cap and systemic cooling in rats with early cerebral ischemia. METHODS: SD rats were randomly divided into model group, ice cap group, systemic cooling group and ICSI group (n=13). Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 2 h. In the 3 hypothermic groups, the target temperature of 33-34 degrees celsius; was achieved and maintained for 20 min. In each group, the neurological scores were recorded at 48 h after the reperfusion, and the brains were removed for measuring the infarct size using 2,3,5-triphenyltetrazolium chloride staining. The brain water contents and serum levels of neuron-specific enolase (NSE), S100β and matrix metalloproteinase 9 (MMP9) were also measured. RESULTS: Compared with the model group, the ice cap, systemic cooling and ICSI groups all showed significantly reduced infarct size by 27.4% (P<0.05), 47.6% (P<0.01) and 61.6% (P<0.01), respectively. The systemic cooling and ICSI groups, but not the ice cap group, had significantly lower brain water contents than the model group (P<0.05). Among the 3 hypothermic methods, only ICSI significantly improved the neurological scores (P<0.05) and reduced serum NSE and S100β levels (P<0.05). CONCLUSION: Of the 3 hypothermic groups, ICSI has the best neuroprotective effects, and systemic cooling produces better effect than ice cap in rats with ischemic stroke.