Altered immunoreactivity for glial fibrillary acidic protein in astrocytes within 1 h after cervical spinal cord injury.

One hour after a C2 spinal cord hemisection, there are changes in astrocyte morphology and increased glial fibrillary acidic protein immunoreactivity (GFAP IR) near the site of the lesion. Astrocytes adjacent to the lesion display thick, richly branched processes within 1/2 segment rostral and caudal to the level of hemisection. Astrocytes are also enlarged and immunoreactive in gray matter regions of the spinal cord as far caudal as C4 and rostrally to C1. Sham-operated controls, undergoing a laminectomy and durotomy at C2, but not spinal cord hemisection, also exhibit a strong astroglial reaction within 1 h from C1 to C4. However, controls undergoing only a C2 laminectomy do not demonstrate alterations in GFAP IR compared to non-operated controls. The results of this investigation suggest that spinal cord astrocytes are extremely sensitive to both major as well as minor alterations of their microenvironment. Rapid changes in astroglial morphology, as detected by altered GFAP IR, may play a role in changes in neuronal function following spinal cord injury.