Neuropeptides Involved in Facial Nerve Regeneration

Abstract

Neuropeptides and neurotransmitters act as intermediaries to transmit impulses from one neuron to another via a synapse. These neuropeptides are also related to nerve degeneration and regeneration during nerve damage. Although there are various neuropeptides, three are associated with neural regeneration in facial nerve damage: calcitonin gene-related peptide (CGRP), galanin, and pituitary adenylyl cyclase-activating peptide (PACAP). Alpha CGRP in facial motoneurons is a signaling factor involved in neuroglial and neuromuscular interactions during regeneration. Thus, it may be a marker for facial nerve regeneration. Galanin is a marker of injured axons rather than nerve regeneration. PACAP has various effects on nerve regeneration by regulating the surrounding cells and providing neurotrophic factors. Thus, it may also be used as a marker for facial nerve regeneration. However, the precise roles of these substances in nerve generation are not yet fully understood. Animal studies have demonstrated that they may act as neuromodulators to promote neurotrophic factors involved in nerve regeneration as they appear early, before changes in the injured cells and their environment. Therefore, they may be markers of nerve regeneration.

Central Facial Nervous System Biomolecules Involved in Peripheral Facial Nerve Injury Responses and Potential Therapeutic Strategies

“…The molecular response of damaged motor neurons following facial nerve injury involves the upregulation of early genes followed by the expression of neuromodulatory and regeneration-related genes [107]. Calcitonin gene-related peptide (CGRP) is among the early representative genes upregulated in facial nerve nuclei, together with c-Jun and growth-associated protein-43 (GAP-43) [24].…”

Role of neuropeptides in orofacial pain: A literature review

“…Among the aforementioned mediators, neuropeptides have been widely studied in the last four decades. Neuropeptides are neurotransmitters composed of amino acids linked by peptide bonds 8 . After sensory neurons are stimulated, neuropeptides are released from nerve terminals or synaptic clefts and act directly on neurons (nociceptors, TG, and SpVc) or non‐neuronal targets (glial cells, endothelial cells and inflammatory cells), thereby contributing to neurogenic inflammation and orofacial pain.…”

“…Neuropeptides are neurotransmitters composed of amino acids linked by peptide bonds. 8 After sensory neurons are stimulated, neuropeptides are released from nerve terminals or synaptic clefts and act directly on neurons (nociceptors, TG, and SpVc) or non-neuronal targets (glial cells, endothelial cells and inflammatory cells), thereby contributing to neurogenic inflammation and orofacial pain. Previous studies have demonstrated that neuropeptides, including calcitonin generelated peptide (CGRP), 4 substance P (SP), 9 opioid peptides (OP), 10 galanin (GAL), 11 vasoactive intestinal peptide (VIP), 12 neuropeptide Y (NPY), 13 neurokinin A (NKA), 14 orexin-A (OrxA) 15 and oxytocin (OXT), 16 are involved in orofacial pain.…”