Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Feb 27:1196:22-32.
doi: 10.1016/j.brainres.2007.12.028. Epub 2008 Jan 25.

Calcitonin gene-related peptide stimulation of nitric oxide synthesis and release from trigeminal ganglion glial cells

Jing Li  1 , Carrie V Vause, Paul L Durham
Affiliations

Calcitonin gene-related peptide stimulation of nitric oxide synthesis and release from trigeminal ganglion glial cells

Jing Li et al. Brain Res. .

Abstract

Clinical and basic science data support an integral role of calcitonin gene-related peptide (CGRP) in migraine pathology. Following trigeminal nerve activation, afferent release of CGRP causes vasodilation while efferent release leads to pain. Although CGRP can also be secreted from cell bodies of trigeminal neurons located within the ganglion, the function of CGRP released in the ganglion is poorly understood. Initially, we showed that SNAP-25, a protein required for CGRP release, was localized in cell bodies of trigeminal ganglia neurons. We also found that satellite glial cells in the ganglia express the CGRP1 receptor protein RAMP1. To determine whether CGRP could directly activate glial cells, primary cultures of rat trigeminal ganglia were utilized to study the effects of CGRP on glial nitric oxide (NO) synthesis and release. Under our culture conditions, >95% of the cells expressed glial fibrillary acidic protein and RAMP1. While weak iNOS staining was observed in glia under basal conditions, CGRP treatment greatly increased glial iNOS expression and NO release. This stimulatory effect was blocked by the CGRP1 receptor antagonist, CGRP(8-37) peptide. Treatment of glial cultures with forskolin or cAMP also increased iNOS expression and stimulated NO release to levels similar to CGRP. To our knowledge, this is the first evidence that activation of CGRP1 receptors regulates glial iNOS and NO release. We propose that following trigeminal nerve activation, CGRP secretion from neuronal cell bodies activates satellite glial cells that release NO and initiate inflammatory events in the ganglia that contribute to peripheral sensitization in migraine.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Expression of CGRP, RAMP1, and SNAP-25 in trigeminal ganglia. (A) Rat trigeminal ganglion sections of the whole ganglion stained with the fluorescent dye DAPI to identify neuronal and glial cell nuclei. Multiple image alignment was used to generate a view of the entire ganglia. Other sections were immunostained for the expression of CGRP, RAMP1, and SNAP-25. (B) Enlargement of boxed areas shown in A. (C) The same section was stained with DAPI or immunostained for expression of RAMP1. The panel on the right is a merged image of the DAPI and RAMP1 images. Large arrows identify neuronal cell body nuclei while small arrows identify satellite glial cell nuclei. (D) Ganglion section incubated with RAMP1 antibodies preabsorbed with RAMP1 peptide. Scale bar represents 1000 μm in A and 50 μm in C and D.
Fig. 2
Fig. 2
Cultured trigeminal ganglia glial cells express RAMP1. (A) GFAP is expressed in the majority of cultured cells that exhibit glial morphology by phase microscopy. The same cultured cells were costained with DAPI to identify nuclei. (B) Almost all trigeminal ganglion glial cells express the CGRP receptor subunit RAMP1. The same culture was costained with DAPI. (C) Cultured cells incubated with RAMP1 antibodies preabsorbed with RAMP1 peptide and costained with DAPI are shown. (D) Cultured cells incubated with secondary antibodies only and costained with DAPI. Scale bar represents 20 μm.
Fig. 3
Fig. 3
CGRP stimulation of iNOS involves RAMP1. Untreated (control; CON) trigeminal ganglion glial cells were costained with DAPI and antibodies directed against iNOS (A, B) or after 24 h stimulation with 1 μm CGRP (C,D), or treatment with 10 μm CGRP8–37 prior to CGRP stimulation (E, F). Scale bar represents 20 μm.
Fig. 4
Fig. 4
CGRP-stimulated NO release from trigeminal ganglion glial cells. NO levels were determined by the Griess reaction in media collected from untreated control cultures (CON) or 48 h after treatment with 0.02, 0.05, 0.2, 0.5, 1, or 2 μM CGRP or cotreatment with 1 μM CGRP and 10 μM CGRP8–37. *p<0.05.
Fig. 5
Fig. 5
Forskolin and cAMP stimulate iNOS expression. Trigeminal ganglion glial cells that were left untreated (control; CON) or treated for 24 h with 1 μM forskolin (FSK) or 1 μM cAMP were costained with DAPI (left panels) and antibodies directed against iNOS (right panels). Scale bar represents 20 μm.
Fig. 6
Fig. 6
Stimulated NO release from trigeminal ganglion glial cells. NO levels were determined by the Griess reaction in media collected from untreated control cultures (CON) or 48 h after treatment with 0.1, 1, or 10 μM forskolin (A) or 1, 10, or 100 μM cAMP (B). *p<0.05; +p<0.01.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Amara S, Jonas V, Rosenfeld M, Ong E, Evans R. Alternative RNA processing in calcitonin gene expression generates mRNAs encoding different polypeptide products. Nature. 1982;298:240–244. - PubMed
    1. Amir R, Devor M. Chemically mediated cross-excitation in rat dorsal root ganglia. J Neurosci. 1996;16:4733–4741. - PMC - PubMed
    1. Amir R, Devor M. Functional cross-excitation between afferent A- and C-neurons in dorsal root ganglia. Neuroscience. 2000;95:189–195. - PubMed
    1. Bellamy J, Bowen E, Russo A, Durham P. Nitric oxide regulation of calcitonin gene-related peptide gene expression in rat trigeminal ganglia neurons. Eur J Neurosci. 2006a;23:2057–2066. - PMC - PubMed
    1. Bellamy J, Cady R, Durham P. Salivary levels of CGRP and VIP in rhinosinusitis and migraine patients. Headache. 2006b;46:24–33. - PubMed

Publication types

MeSH terms