Delayed neuronal death of the pyramidal neurons in the CA1 subfield of the hippocampus was observed in stroke-prone spontaneously hypertensive rats, SHRSP, when the bilateral common carotid arteries were occluded for 10 min. To elucidate the mechanism of the neuronal death produced only by the occlusion of the carotid arteries, the vulnerability of SHRSP to ischemic insult, we have been studying the substances expressed by glial cells and the permeability of blood-brain barriers. In this review we described in detail about the expression of monocyte chemoattractant protein-1 (MCP-1) after 2 vessel-occlusion to clarify the involvement of the infiltration of blood monocytes in the mechanism of the neuronal death. MCP-1 mRNA was clearly expressed in the molecular layer of the dentate gyrus at 1 day after the ischemia-reperfusion and in the entire CA1 subfield at 2 days after 2 vessel-occlusion. Most of the cells expressing MCP-1 were astrocytes. The concentration of MCP-1 protein dramatically increased in the hippocampus at 2 days after 2 vessel-occlusion. Taken together with the findings of our previous study showing an increased permeability of the blood-brain barrier in the hippocampus from 12 h after ischemia-reperfusion, the astrocytes expressing MCP-1 might therefore induce the migration of monocytes into the brain parenchyma. As a result, such astrocytes expressing MCP-1 may therefore be related to the pathological events of delayed neuronal death in the pyramidal neurons.