In vitro activation of murine DRG neurons by CGRP-mediated mucosal mast cell degranulation.
Upregulation of CGRP-immunoreactive (IR) primary afferent nerve fibers accompanied by mastocytosis is characteristic for the Schistosoma mansoni-infected murine ileum. These mucosal mast cells (MMC) and CGRP-IR fibers, which originate from dorsal root (DRG) and nodose ganglia, are found in close apposition. We examined interactions between primary cultured MMC and CGRP-IR DRG neurons in vitro by confocal recording of intracellular Ca(2+) concentration ([Ca(2+)](i)). The degranulatory EC(50) for the mast cell secretagogue compound 48/80 (C48/80; 10 microg/ml) and the neuropeptides CGRP (2.10(-8) M) and substance P (SP; 3.10(-8) M) were determined by measurement of extracellular release of the granule chymase, mouse mast cell protease-1. Application of C48/80 (10 microg/ml) and CGRP and SP (both 10(-7) M) to Fluo-4-loaded MMC induced a transient rise in [Ca(2+)](i) after a lag time, indicative of mast cell degranulation and/or secretion. The CGRP response could be completely blocked by pertussis toxin (2 microg/ml), indicating involvement of G(i) proteins. Application of MMC juice, obtained by C48/80 degranulation of MMC, to Fluo-4-loaded DRG neurons induced in all neurons a rise in [Ca(2+)](i), indicative of activation. Degranulation of MMC by C48/80 in culture dishes containing Fluo-4-loaded DRG neurons also caused activation of the DRG neurons. In conclusion, these results demonstrate a bidirectional cross-talk between cultured MMC and CGRP-IR DRG neurons in vitro. This indicates that such a communication may be the functional relevance for the close apposition between MMC and CGRP-IR nerve fibers in vivo.
De Jonge
F
F
Laboratory of Cell Biology and Histology, Department of Biomedical Sciences, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. jean-pierre.timmermans@ua.ac.be
De Laet
A
A
Van Nassauw
L
L
Brown
J K
JK
Miller
H R P
HR
van Bogaert
P-P
PP
Timmermans
J-P
JP
Kroese
A B A
AB
D000818:Animals; D001826:Body Fluids / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism* / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000502:physiology*; D002478:Cells, Cultured; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008407:Mast Cells / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000502:physiology*; D009994:Osmolar Concentration; D013373:Substance P / Q000494:pharmacology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
D013373:Substance P; D003189:p-Methoxy-N-methylphenethylamine; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium