Primary Afferents Containing Calcitonin Gene-Related Peptide and Substance P Form Complex Synaptic Arrangements in Human Spinal Dorsal Horn

Unmyelinated C-fibres have been classically defined as peptidergic or non-peptidergic based on the presence or absence of calcitonin gene-related peptide and/or substance P. Peptidergic primary afferents terminate in lamina I of the rodent spinal dorsal horn, where they form simple synaptic arrangements. In contrast, the axonal boutons of non-peptidergic afferents make multiple output synapses and have been shown to form the central axon of type I glomeruli. There is an expansion in the expression of these peptides in humans as a greater proportion of primary afferents contain the mRNA for the peptide precursor proteins than in the rodent.
Source: The Journal of Pain - Category: Materials Science Authors: Source Type: research