In vivo electrophysiological recordings for the dorsal spinal cord before and after peptide administration following stimulation of the peripheral sural nerve at intensities sufficient to activate C and Aδ fibres. Illustration of the experimental setup indicating where measurements were made (image made using Biorender.com).   Example of field potentials recorded in the same position before (black) and after (blue) peptide administration. The recording starts with a 1mV calibration pulse followed by a stimulus artefact (S) which is truncated for the figure and finally the field potential at a depth corresponding to lamina 1. Each trace is an average of at least 10 successive trials.   