EFFECT OF UNILATERAL MOTOR CORTEX ABLATION ON ACTIVITY OF CHOLINE-ACETYLTRANSFERASE AND LEVELS OF AMINO-ACID TRANSMITTER CANDIDATES IN THE SPINAL-CORD OF ADULT MONKEYS
K. Fujita et al., EFFECT OF UNILATERAL MOTOR CORTEX ABLATION ON ACTIVITY OF CHOLINE-ACETYLTRANSFERASE AND LEVELS OF AMINO-ACID TRANSMITTER CANDIDATES IN THE SPINAL-CORD OF ADULT MONKEYS, Neurochemical research, 18(7), 1993, pp. 731-736
Evidence that L-glutamate is a neurotransmitter of corticofugal fibers
was sought by measuring changes in several biochemical markers of neu
rotransmitter function in discrete regions of spinal cord after ablati
on of sensorimotor cortex in monkeys. One and five weeks after unilate
ral cortical ablation, samples from six areas of spinal cord (ventral,
lateral and dorsal regions of the left and right sides) were analysed
for choline acetyltransferase (ChAT) activity and contents of amino a
cid transmitter candidates -glutamic acid (Glu), aspartic acid (Asp),
glycine (Gly), taurine (Tau) and gamma-aminobutyric acid (GABA). Durin
g one to five weeks after unilateral cortical ablation of the monkey,
prolonged hemiplegia in the contralateral side was observed. Histologi
cal examination of the spinal cord 5 weeks after unilateral (left) cor
tical ablation showed no apparent change in either control (ipsilatera
l, left) or affected (contralateral, right) sides of the cord as exami
ned by the Kluver-Barrera method. The ChAT activity as a cholinergic m
arker was scarcely changed in any region of either left (control) or r
ight (affected) side of the spinal cord at one and five weeks after un
ilateral (left side) ablation of the motor cortex. Amino acid levels i
n each region of the spinal cord were not significantly changed one we
ek after unilateral ablation of the motor cortex. However, a significa
nt decrease of Glu content was observed in the lateral column of the a
ffected (right) side compared to the control (left) side of cervical a
nd lumbar cord five weeks after cortical ablation of the left motor ar
ea. No concomitant alterations of other amino acids were detected. The
se data strongly suggest that L-Glu is a neurotransmitter for corticof
ugal pyramidal tract fibers to anterior horn secondary neurons related
to motor control activity in monkey spinal cord.