Effect of Strychnine on Dorsal Root Potentials and Amino Acid Responses in Frog Spinal Cord

Abstract

STRYCHNINE blocks both the postsynaptic inhibition of spinal motoneurones and interneurones and the inhibitory action of glycine-like amino acids (such as glycine, taurine and β-alanine (BALA)) on these neurones in the cat^{1, 2}. These observations provide strong evidence that glycine or a closely related compound mediates spinal postsynaptic inhibition^1–3 . Recently, several amino acids with postsynaptic inhibitory effects (such as γ-aminobutyric acid (GABA), BALA and glycine) have been shown to depolarise the primary afferent terminals in an isolated frog spinal cord^4–6, and GABA has been proposed as a possible synaptic transmitter mediating primary afferent depolarisation^{5, 6}. However, the fact that the glycine-like amino acids also depolarise the primary afferents in addition to GABA has prompted this study on the action of strychnine in this system.