[Effect of neutral amino acids on neurons and synaptic transmission in the isolated rat spinal cord]

GABA, glycine and beta-alanine depolarized motoneurons and primary afferents of the isolated spinal cord of rats of 10-14-day age. The blockade of synaptic transmission in the spinal cord by abundant Mg++ ions turns the depolarization into hyperpolarizing responses. Depolarization of the primary afferents evoked by glycine is antagonized by strychnine, picrotoxin reduces the GABA effects, and both convulsants diminish the beta-alanine effects. Neural amino acids reduce both ventral and dorsal root potentials. Strychnine and picrotoxin increase the amplitude and duration of ventral root potentials. Picrotoxin decreases the amplitude of dorsal root potentials.