Early microglial reaction following mild forebrain ischemia induced by common carotid artery occlusion in rats

Early microglial reaction following mild ischemic injury caused by bilatera l common carotid artery occlusion has been investigated in rats. The ischem ic insults lasted for 10, 15 and 20 min without recirculation, and with sev eral reperfusion intervals from 1 h to 3 days. The resting and activated mi croglial cells were visualized with immunohistochemistry using monoclonal a ntibodies raised against the CR3 complement receptor, the MHC class I and c lass II antigens, the macrophage common antigen and with Bandeiiraea simpli cifolia lectin-histochemistry. The neuroprotective effect of hypothermia on the early microglial activation was also studied. Ten minutes bilateral co mmon carotid artery occlusion in hypothermic rats without reperfusion cause d a mild microglial reaction in the hippocampus. Strong reaction was seen f ollowing 20 min insult without reperfusion. Ischemia followed by recirculat ion caused milder reaction than without reperfusion. Our results suggest th at the microglial cells are very sensitive indicators of a mild, transient ischemic insult that does not result in neuronal cell death. (C) 2000 Elsev ier Science B.V. All rights reserved.