NEURONAL DEGENERATION AND SPINAL CAVITATION FOLLOWING INTRASPINAL INJECTIONS OF QUISQUALIC ACID IN THE RAT

Microinjections of quisqualic acid were made in the spinal cord to eva luate the excitotoxic effects of this excitatory amino acid agonist on spinal neurons in the rat. Animals were divided into four groups base d on post injection survival times of 7-49 days. Injections ranging fr om 0.3 to 2.0 mu L of 8.3, 83, and 125 mM quisqualic acid or normal sa line were made in the lower thoracic and upper lumbar spinal cord. At all survival times evaluated unilateral injections of quisqualic acid produced unilateral or bilateral cell death and a prominent inflammato ry reaction. In 23/25 animals spinal cavities were also observed. Spin al cord segments at or near quisqualate injection sites contained dark ly stained, hypertrophied neuronal profiles, and increased staining fo r glial fibrillary acidic factor. Immunostaining for glial fibrillary acidic factor was especially intense in areas of neuronal degeneration and in border areas of spinal cavities. The results of this study sug gest that the intraspinal injection of quisqualic acid may be an effec tive method to study the mechanisms of excitatory amino acid neurotoxi city, and the pathogenesis of spinal cavitation following neuronal inj ury.