To observe the effect of hypothermia on amino acid release in ischemic side of brain in gerbils.

18 male Mongolian gerbils were all subjected to 30 min of unilateral internal carotid artery occlusion，and were randomly divided into the normothermia and hypothermia groups with each group 9 animals. Hippocampal concentrations of glutamate，glycine and gamma-amino butyric acid （GABA） of the ischemic side in both groups were monitored using in vivo microdialysis combined with high performance liquid chromatography （HPLC） method.

The concentrations of glutamate and glycine in the normothermic group after ischemia were elevated significantly but not in the hypothermic group. During the reperfusion period the GABA concentration in the normothermic group decreased quickly，whereas that in the hypothermic group sustained long at high level. And during the ischemic and reperfusion period，the excitotoxic indexes （glu conc×gly conc÷GABA conc） of the hypothermic group were strikingly lower than that of the normothermic group（P<0.01）.

The neuroprotective property of hypothermia may be due to its ability to decrease extracellular excitotoxic index.