کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6263906 | 1613936 | 2013 | 9 صفحه PDF | دانلود رایگان |
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 Ca2+ is a key regulator of neuronal excitability and is largely controlled by the Ca2+ stores of the endoplasmic reticulum. In other cell types store-operated channels (SOC) have been shown to contribute to the homeostatic control of intracellular Ca2+. Here, using Ca2+ imaging, we have shown that ER depletion in vagal sensory neurons (using thapsigargin or caffeine) in the absence of extracellular Ca2+ evoked Ca2+ influx upon re-introduction of Ca2+ into the extracellular buffer. This store-operated Ca2+ entry (SOCE) was observed in approximately 25-40% of vagal neurons, equally distributed among nociceptive and non-nociceptive sensory subtypes. SOCE was blocked by Gd3+ 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 Ca2+ 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.
1) Current evidence of store-operated Ca2+ entry (SOCE) in vagal sensory neurons is lacking. 2) ER store depletion evoked store-operated Ca2+ entry (SOCE) in vagal sensory neurons. 3) SOCE is inhibited by extracellular Gd3+ ions. 4) SOCE is not inhibited by Orai inhibitor SKF96365 and Orai mRNA is not present in vagal neurons. 5) SOCE is not observed in vagal neurites that contain ER.
Journal: Brain Research - Volume 1503, 29 March 2013, Pages 7-15