First-order nociceptive synapses in rat dorsal horn are blocked by an amino acid antagonist

An antagonist to amino acid evoked excitation, gamma-D-glutamylglycine (gamma-DGG) inhibits, dose-dependently, nociceptive C-fibre evoked field potentials and neuronal discharges in single nociceptive neurons in rat spinal cord. It is concluded that amino acids are possible transmitter substance(s) in nociceptive afferent C-fibres. These results might be useful for development of centrally acting analgesic drugs.