Influence of selective brain cooling on the expression of ICAM-1 mRNA and infiltration of PMNLs and monocytes/macrophages in rats suffering from global brain ischemia/reperfusion injury

Abstract

This study sought to evaluate the effects of selective brain cooling on the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA and infiltration of polymorphonuclear leukocytes (PMNLs) and monocytes/macrophages (MPhi) during global cerebral ischemia/ reperfusion (I/R). Global ischemia of the brain was produced by four-vessel occlusion for 30 min followed by reperfusion for 240 min. Thirty-five SD rats were randomly divided into five groups: group I had no ischemia and reperfusion; groups II, III, IV, and V were subjected to ischemia for 30 min at 37 degrees C and reperfusion for 240 min at 37, 35, 32, and 28 degrees C, respectively. Cerebral tissue samples were taken for pathological examination of the infiltration of PMNLs and MPhi and to detect ICAM-1 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). The expression of ICAM-1 mRNA and infiltration of PMNLs and MPhi increased more markedly in group II than in group I (p < 0.01), suggesting that hypothermia evidently inhibited ICAM-1 mRNA expression and PMNL and MPhi infiltration in the damaged cerebral tissue. In addition, significant differences were also found between group III and group II (p < 0.05) and among groups IV, V, and II (p < 0.01). These results suggest that I/R injury induces ICAM-1 mRNA expression and PMNL and MPhi infiltration in SD rats and that selective brain cooling, and especially moderate hypothermia (28-32 degrees C), may provide better cerebral protection by markedly inhibiting the expression of ICAM-1 mRNA while decreasing the infiltration of PMNLs and MPhi in the brain.