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Decreased Uptake and Release of D‐Aspartate in the Guinea Pig Spinal Cord After Partial Cordotomy
Author(s) -
Potashner S. J.,
Tran P. L.
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb08789.x
Subject(s) - cordotomy , spinal cord , lesion , rhizotomy , glutamate receptor , anatomy , central nervous system , neuroscience , anesthesia , biology , medicine , pathology , receptor
This study attempts to determine if L‐glutamate and/or L‐aspartate may be transmitters of neural tracts descending from the brain to the spinal cord. The uptake and electrically evoked release of D‐[ 3 H]aspartate, a putative marker for L‐glutamate and L‐aspartate, were measured in the cervical enlargement of the guinea pig spinal cord. These activities were compared using unlesioned animals and others with a lesion on the right side of the spinal cord. Partial cordotomy (segment C5) produced a heavy loss of descending fibers, a small loss of primary sensory fibers, and a depression of the uptake and the Ca 2+ ‐dependent, electrically evoked release of D‐aspartate ipsilateral and caudal to the lesion. Contralaterally, there was a moderate loss of corticospinal fibers, some loss of other descending axons, and a depression of D‐aspartate release. Dorsal rhizotomy (segments C4–T1) produced a heavy loss of primary sensory fibers ipsilateral to the lesion. Ipsilaterally, but not contralaterally, the uptake and release of D‐aspartate were depressed. Degeneration after partial cordotomy in combination with dorsal rhizotomy was assumed to be the sum of that produced by each lesion separately. This combined lesion depressed D‐aspartate uptake ipsilaterally and depressed D‐aspartate release on both sides of the cervical enlargement. None of the lesions altered the up‐take and the evoked release of [ 3 H]GABA. These findings support the hypothesis that the synaptic endings of one or more neural tracts descending from the brain to the spinal cord mediate the uptake and release of D‐aspartate and, therefore, may use L‐glutamate or L‐aspartate as a transmitter.