Synaptic transmission in the dorsal horn
• Nociceptors synapse with dorsal horn neurons in lamina I,
II, and V
• Nociceptors  and local excitatory interneurons release
glutamate as the fast transmitter, some also release co-
transmitters such as peptides with slower excitatory action
• Local inhibitory interneurons release GABA and glycine as
fast transmitters, some also release co-transmitters.
• Descending inputs synapse with projection neurons,
interneurons, and terminals of the nociceptors