[Effect of N-methyl-D-aspartate on the spontaneous activity generated by isolated spinal cord of 16 to 20-day-old chick embryos]

Bath-application of N-methyl-D-aspartate (NMDA) and antagonist of NMDA-receptors 2-amino-5-phosphonovaleric acid (2-APV) has been studied from the standpoint of its effect on the spontaneous activity in dorsal and ventral roots (DR and VR, respectively) generated by isolated spinal cord of 16-20-day-old chick embryo. Spontaneous activity consisted of synchronous oscillations of electrotonic potentials in DR and VR. Bath-application of NMDA (2-25 mumol/l) increased amplitude of the electrotonic potentials, induced spice discharges in DR and VR, a tonic component of electrotonic potentials. Bath-application of 2-APV (20 mumol/l) depressed spontaneous and NMDA-induced activity. The neuronal network of isolated dorsal horn (after splitting of the spinal cord) retained ability to generate spontaneous activity in DR which was intensified after bath-application of NMDA. No rhythmic activity appeared in the ventral part of the cord. The location of NMDA-sensitive neuronal network generating rhythmic (motor) activity in the spinal cord is discussed.