Dual ultrastructural localization of ?-opiate receptors and substance p in the dorsal horn

摘要: Opiates active at the mu-opiate receptor (MOR) produce antinociception, in part, through actions involving substance P (SP), a peptide present both unmyelinated primary afferents and interneurons within dorsal horn. We examined potential functional sites for interactions between SP MOR by using dual electron microscopic immunocytochemical localization of antisera against sequence-specific antipeptide antibody rat cervical spinal The distribution was compared with that functionally analogous horn trigeminal nucleus caudalis. Many SP-immunoreactive terminals contacted dendrites contain (53% trigeminal; 70% cord). Conversely, 79% MOR-labeled received any afferent input were least one SP-containing axon or terminal. Although rare, many these (48%) contained MOR, suggesting activity may be regulated ligands. A few SP-labeled also (12% 6% These data support idea ligands antinociception primarily modulation postsynaptic second-order nociceptive neurons horns cord nuclei, some which SP. They suggest, however, each region, agonists can act presynaptically to control release and/or glutamate from terminals. post- presynaptic are likely account potency as analgesics.