DORSAL RHIZOTOMY INDUCES TRANSIENT EXPRESSION OF THE HIGHLY SIALYLATED ISOFORM OF THE NEURAL CELL-ADHESION MOLECULE IN NEURONS AND ASTROCYTES OF THE ADULT-RAT SPINAL-CORD

Expression of the weakly adhesive, highly sialylated isoform of the ne ural cell adhesion molecule is a feature common to cells capable of mi gration and conformation changes.(11,18,19) Polysialylated neural cell adhesion molecule also intervenes in axonal outgrowth and synaptogene sis during development and after lesion.(11,13) High levels of polysia lylated neural cell adhesion molecule immunoreactivity are normally vi sible in laminae I, II and X of the adult rat spinal cord.(2,15) We sh ow here that unilateral cervical dorsal rhizotomy induced no detectabl e changes in immunoreactivity in these areas, However, 24 h after lesi on, polysialylated neural cell adhesion molecule immunoreactivity appe ared in neurons scattered in laminae III-IX, ipsi- and contralateral t o lesion, This reaction increased particularly on the contralateral si de, became maximal at four days and disappeared eight days later, At t his time, there was immunolabelling of astrocytes with an activated mo rphology. The astrocytic labelling, predominant on the side ipsilatera l to the lesion, was strongest 12 days after rhizotomy, then diminishe d progressively, Deafferentation thus causes a transient expression of polysialylated neural cell adhesion molecule within areas of the spin al cord distinct from those which permanently express this adhesion mo lecule, Such expression occurs both in neurons and glial cells, with a temporal pattern specific to each type of cell, Copyright (C) 1996 IB RO.