Morphological characteristics of lectin labeled microglial cells in the ischemic rat spinal cord

Injury to the spinal cord leads to cellular changes not only in the affected neurons but also in adjacent resident microglial cells. This study examines the microglial response to transient spinal cord ischemia induced by 8, 10 and 12 min of aorta cross-clamping linked with blood volume reduction. The microglial cells visualized by Griffonia simplicifolia B(4)-isolectin (GSA I-B(4)HRP) were studied in vibratome sections from the lumbosacral spinal cord segments (L(3)-S(2)). A distinct type of morphological transformation of microglia characterized by both, increased lectin-binding and altered cell shape, was observed in all spinal cords subjected to transient ischemia. Our results show, that the activation of resident microglia, represented by their morphological transformation occurs in a graded fashion in response to different degrees of ischemic attack within 2-3 days of postischemic reperfusion. The response of microglia was, in addition, closely related to the neurological outcome examined at the end of the post-ischemic reperfusion period (1-7 days). We show that lectin labeling can serve for the continuous study of microglial morphological transformation under conditions of transient spinal cord ischemia.