SENSORIMOTOR IMPAIRMENTS IN RATS WITH CEREBRAL INFARCTION, INDUCED BYUNILATERAL OCCLUSION OF THE LEFT MIDDLE CEREBRAL-ARTERY - STRAIN DIFFERENCES AND EFFECTS OF THE OCCLUSION SITE

Enormous differences exist between rat strains with respect to the inf arct volume induced by unilateral middle cerebral artery (MCA) occlusi on. We performed three experiments to address the following questions. Firstly, whether the pattern of MCA-occlusion (MCA-O) induced sensori motor impairments in rats are strain dependent; secondly, whether prox imal (i.e., close to its origin) and distal occlusions (above the lent iculostriate branch) of the MCA affect infarct volume and the behavior al impairments to a different extent; and thirdly, whether there is a relationship between the infarct volume and behavioral deficits. We fo und that the pattern of sensorimotor malfunctions induced by proximal unilateral MCA-O were highly strain dependent. Of the eight strains te sted, Winkelmann-Wistar rats, Spontaneously Hypertensive Stroke-Prone rats, and Wistar-Kyoto rats were most severely affected. By contrast, Brown-Norway rats showed only mild behavioral deficits after the MCA-O . The second experiment confirmed that proximal occlusions induced sli ghtly more behavioral malfunctions than distal occlusions did. Histolo gical evaluation of the brain damage caused by proximal and distal MCA -O, confirmed that distal MCA-O damaged nearly exclusively cortical ar eas, and spared the caudate/putamen. An exploratory analysis of the re lationship between infarct volume and behavioral deficits did not indi cate that the severity of sensorimotor malfunctions can be predicted f rom the size of the infarct.