Dynorphin A(1-8) immunoreactive cell bodies, dendrites and terminals are postsynaptic to calcitonin gene-related peptide primary afferent terminals in the monkey dorsal horn

In the present study, Dynorphin A(1-8) (DYN)-immunoreactive cell bodies, dendrites and terminals are observed postsynaptic to calcitonin gene-related peptide (CGRP)-immunoreactive terminals in laminae I and II. With the demonstration of axosomatic, axodendritic as well as axoaxonic interactions, we hypothesize that CGRP-containing primary afferent terminals can effect processing at the level of the cell body (possibly influencing the manufacture of DYN and/or the firing rate of DYN-containing cells) and also modulate the output of DYN terminals in laminae I and II of the monkey dorsal horn. These structural relationships may play an important role in the processing of noxious input at the spinal cord level.