Motor activity induced by disinhibition of the primary motor cortex of the rat is blocked by a non-NMDA glutamate receptor antagonist

Abstract

Application of a GABA A (γ-aminobutyric acid-A) receptor antagonist through a microdialysis probe into the forelimb primary motor cortex of ketamine-anesthetized rats induced electromyographic activity in the contralateral forelimb. This activity consisted of spontaneous forelimb movements with a frequency of 0.8 ± 0.2 Hz. The motor activity induced by GABA A receptor blockade was suppressed by application through the dialysis probe of a non-NMDA ( N- methyl- d-aspartate ) receptor antagonist, but not by an NMDA receptor antagonist. Glutamate eliminated the blocking effect of the non-NMDA receptor antagonist upon GABA A receptor blockade mediated activity. In conclusion, the results show that an excitatory input to the motor cortical output is mediated through a non-NMDA receptor, therefore the effects of cortical disinhibition may be controlled by non-NMDA receptors.