Pulsed infrared releases Ca2+from the endoplasmic reticulum of cultured spiral ganglion neurons
| Autor: | John N. Barrett, Cristina Matthewman, Samantha Rincon, Ellen F. Barrett, Suhrud M. Rajguru, Julio Pasos, Jayanti Singh |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
TRPV4 Physiology Infrared Chemistry General Neuroscience Endoplasmic reticulum Photothermal therapy 03 medical and health sciences Transient receptor potential channel 030104 developmental biology 0302 clinical medicine medicine.anatomical_structure Optical stimulation medicine Biophysics Receptor 030217 neurology & neurosurgery Spiral ganglion |
| Zdroj: | Journal of Neurophysiology. 120:509-524 |
| ISSN: | 1522-1598 0022-3077 |
| Popis: | Inner ear spiral ganglion neurons were cultured from day 4 postnatal mice and loaded with a fluorescent Ca2+indicator (fluo-4, -5F, or -5N). Pulses of infrared radiation (IR; 1,863 nm, 200 µs, 200–250 Hz for 2–5 s, delivered via an optical fiber) produced a rapid, transient temperature increase of 6–12°C (above a baseline of 24–30°C). These IR pulse trains evoked transient increases in both nuclear and cytosolic Ca2+concentration ([Ca2+]) of 0.20–1.4 µM, with a simultaneous reduction of [Ca2+] in regions containing endoplasmic reticulum (ER). IR-induced increases in cytosolic [Ca2+] continued in medium containing no added Ca2+(±Ca2+buffers) and low [Na+], indicating that the [Ca2+] increase was mediated by release from intracellular stores. Consistent with this hypothesis, the IR-induced [Ca2+] response was prolonged and eventually blocked by inhibition of ER Ca2+-ATPase with cyclopiazonic acid, and was also inhibited by a high concentration of ryanodine and by inhibitors of inositol (1,4,5)-trisphosphate (IP3)-mediated Ca2+release (xestospongin C and 2-aminoethoxydiphenyl borate). The thermal sensitivity of the response suggested involvement of warmth-sensitive transient receptor potential (TRP) channels. The IR-induced [Ca2+] increase was inhibited by TRPV4 inhibitors (HC-067047 and GSK-2193874), and immunostaining of spiral ganglion cultures demonstrated the presence of TRPV4 and TRPM2 that colocalized with ER marker GRP78. These results suggest that the temperature sensitivity of IR-induced [Ca2+] elevations is conferred by TRP channels on ER membranes, which facilitate Ca2+efflux into the cytosol and thereby contribute to Ca2+-induced Ca2+-release via IP3and ryanodine receptors.NEW & NOTEWORTHY Infrared radiation-induced photothermal effects release Ca2+from the endoplasmic reticulum of primary spiral ganglion neurons. This Ca2+release is mediated by activation of transient receptor potential (TRPV4) channels and involves amplification by Ca2+-induced Ca2+-release. The neurons immunostained for warmth-sensitive channels, TRPV4 and TRPM2, which colocalize with endoplasmic reticulum. Pulsed infrared radiation provides a novel experimental tool for releasing intracellular Ca2+, studying Ca2+regulatory mechanisms, and influencing neuronal excitability. |
| Databáze: | OpenAIRE |
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