title: Calcitonin gene-related peptide enhances release of native brain-derived neurotrophic factor from trigeminal ganglion neurons.
abstract: Activity-dependent plasticity in nociceptive pathways has been implicated in pathomechanisms of chronic pain syndromes. Calcitonin gene-related peptide (CGRP), which is expressed by trigeminal nociceptors, has recently been identified as a key player in the mechanism of migraine headaches. Here we show that CGRP is coexpressed with brain-derived neurotrophic factor (BDNF) in a large subset of adult rat trigeminal ganglion neurons in vivo. Using ELISA in situ, we show that CGRP (1-1000 nM) potently enhances BDNF release from cultured trigeminal neurons. The effect of CGRP is dose-dependent and abolished by pretreatment with CGRP receptor antagonist, CGRP(8-37). Intriguingly, CGRP-mediated BDNF release, unlike BDNF release evoked by physiological patterns of electrical stimulation, is independent of extracellular calcium. Depletion of intracellular calcium stores with thapsigargin blocks the CGRP-mediated BDNF release. Using transmission electron microscopy, our study also shows that BDNF-immunoreactivity is present in dense core vesicles of unmyelinated axons and axon terminals in the subnucleus caudalis of the spinal trigeminal nucleus, the primary central target of trigeminal nociceptors. Together, these results reveal a previously unknown role for CGRP in regulating BDNF availability, and point to BDNF as a candidate mediator of trigeminal nociceptive plasticity.
authors.affiliation: Department of Integrative Biosciences, Oregon Health and Science University, Portland, Oregon 97239, USA.
authors.forename: Ilya
authors.initials: I
authors.lastname: Buldyrev
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Tanner
authors.forename: Hui-ya
authors.initials: HY
authors.lastname: Hsieh
authors.forename: Emily G
authors.initials: EG
authors.lastname: Dodd
authors.forename: Loi T
authors.initials: LT
authors.lastname: Nguyen
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Balkowiec
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology / Q000502:physiology*; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D008297:Male; D016253:Microscopy, Immunoelectron; D008881:Migraine Disorders / Q000378:metabolism / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009619:Nociceptors / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D010446:Peptide Fragments / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism; D014275:Trigeminal Caudal Nucleus / Q000378:metabolism / Q000648:ultrastructure; D012668:Trigeminal Ganglion / Q000378:metabolism* / Q000503:physiopathology / Q000648:ultrastructure
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D010446:Peptide Fragments; D018015:Receptors, Calcitonin Gene-Related Peptide; D015740:Calcitonin Gene-Related Peptide