title: Store-operated calcium entry in vagal sensory nerves is independent of Orai channels.
abstract: Vagal sensory nerves innervate the majority of visceral organs (e.g., heart, lungs, GI tract, etc) and their activation is critical for defensive and regulatory reflexes. Intracellular Ca(2+) is a key regulator of neuronal excitability and is largely controlled by the Ca(2+) stores of the endoplasmic reticulum. In other cell types store-operated channels (SOC) have been shown to contribute to the homeostatic control of intracellular Ca(2+). Here, using Ca(2+) imaging, we have shown that ER depletion in vagal sensory neurons (using thapsigargin or caffeine) in the absence of extracellular Ca(2+) evoked Ca(2+) influx upon re-introduction of Ca(2+) into the extracellular buffer. This store-operated Ca(2+) entry (SOCE) was observed in approximately 25-40% of vagal neurons, equally distributed among nociceptive and non-nociceptive sensory subtypes. SOCE was blocked by Gd(3+) but not by the Orai channel blocker SKF96365. We found Orai channel mRNA in extracts from whole vagal ganglia, but when using single cell RT-PCR analysis we found only 3 out of 34 neurons expressed Orai channel mRNA, indicating that Orai channel expression in the vagal ganglia was likely derived from non-neuronal cell types. Confocal microscopy of vagal neurons in 3 day cultures demonstrated rich ER tracker fluorescence throughout axonal and neurite structures and ER store depletion (thapsigargin) evoked Ca(2+) transients from these structures. However, no SOCE could be detected in the axonal/neurite structures of vagal neurons. We conclude that SOCE occurs in vagal sensory neuronal cell bodies through non-Orai mechanisms but is absent at nerve terminals.
authors: Department of Molecular Pharmacology & Physiology, College of Medicine, University of South Florida, 12901 Bruce B Downs Blvd, Tampa, USA. jhooper@health.usf.edu
authors: Justin Shane
authors: JS
authors: Hooper
authors: Stephen H
authors: SH
authors: Hadley
authors: Adithya
authors: A
authors: Mathews
authors: Thomas E
authors: TE
authors: Taylor-Clark
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D000071740:ORAI1 Protein; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D000074025:TRPA1 Cation Channel; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D050051:Transient Receptor Potential Channels / Q000172:deficiency; D014630:Vagus Nerve / Q000166:cytology
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D007093:Imidazoles; D000071740:ORAI1 Protein; C520430:Orai1 protein, mouse; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse; D002110:Caffeine; D019284:Thapsigargin; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium
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