Fig. 1

Effects of OT and PRL on sensory nerves in the trigeminal system. Intranasal OT can reach the trigeminal system and activate the OTR, resulting in inhibition of CGRP release [195], desensitisation of TRPV1 channels [199] and inhibition of neuronal firing [200], leading to antinociceptive effects. PRL activates the PRLR, resulting in increased neuronal excitability [14, 99], sensitization of TRPV1, TRPM8 and TRPA1 channels [33, 79, 102, 105], and release of CGRP [15, 82], suggesting that treatment targeting PRL should aim to decrease its pronociceptive effects, e.g. using PRLR antagonists or decreasing PRL levels