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Ca 2+ ‐dependent and Ca 2+ ‐independent somatic release from trigeminal neurons
Author(s) -
Sforna Luigi,
Franciolini Fabio,
Catacuzzeno Luigi
Publication year - 2019
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.27901
Subject(s) - trigeminal ganglion , chemistry , dorsal root ganglion , neuroscience , extracellular , voltage dependent calcium channel , somatic cell , biophysics , channel blocker , calcium , sensory system , anatomy , microbiology and biotechnology , biology , biochemistry , organic chemistry , gene
Besides the nerve endings, the soma of trigeminal neurons also respond to membrane depolarizations with the release of neurotransmitters and neuromodulators in the extracellular space within the ganglion, a process potentially important for the cross‐communication between neighboring sensory neurons. In this study, we addressed the dependence of somatic release on Ca 2+ influx in trigeminal neurons and the involvement of the different types of voltage‐gated Ca 2+ (Cav) channels in the process. Similar to the closely related dorsal root ganglion neurons, we found two kinetically distinct components of somatic release, a faster component stimulated by voltage but independent of the Ca 2+ influx, and a slower component triggered by Ca 2+ influx. The Ca 2+ ‐dependent component was inhibited 80% by ω‐conotoxin‐MVIIC, an inhibitor of both N‐ and P/Q‐type Cav channels, and 55% by the P/Q‐type selective inhibitor ω‐agatoxin‐IVA. The selective L‐type Ca 2+ channel inhibitor nimodipine was instead without effect. These results suggest a major involvement of N‐ and P/Q‐, but not L‐type Cav channels in the somatic release of trigeminal neurons. Thus antinociceptive Cav channel antagonists acting on the N‐ and P/Q‐type channels may exert their function by also modulating the somatic release and cross‐communication between sensory neurons.