Relation between expression of the peptides and their receptors.
CGRP and CT were found to be co-expressed in small to medium sized neurons, and in some SGCs, suggesting that CT might have a role in trigeminal function (Edvinsson, Grell & Warfvinge, 2020). CGRP and AMY are co-expressed in some of the small to medium sized neurons and in thin C-fibres. The number of CGRP positive cells were in abundance compared to those storing AMY (Edvinsson, Grell & Warfvinge, 2020). AMY is present in high concentrations in plasma, in migraine attacks higher levels of CGRP is released than AMY. Since the CGRP receptor is more sensitive to CGRP than to AMY, AMY is unlikely to have a central role in migraine.
The CGRP receptor (CLR/RAMP1) is mainly expressed in large neurons and SGCs (Edvinsson, Grell & Warfvinge, 2020). The AM2receptor (CLR/RAMP3) occurs in some SGCs, the AMY1receptor (CTR/RAMP1) in large neurons and SGCs, while the AMY3 receptor (CTR/RAMP3) has been observed in some SGCs.