OBJECTIVETo compare the neuroprotective effects of intracarotid cold saline infusion (ICSI), ice cap and systemic cooling in rats with early cerebral ischemia.

METHODSSD 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.

RESULTSCompared 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).

CONCLUSIONOf the 3 hypothermic groups, ICSI has the best neuroprotective effects, and systemic cooling produces better effect than ice cap in rats with ischemic stroke.