-Shogaol Induces Ca2+ Signals by Activating the TRPV1 Channels in the Rat Insulinoma INS-1E Cells
Context -shogaol is a vanilloid compound present in steamed ginger (Zingiber officinale), a commonly used spice. Pancreatic beta-cells respond to nutrients like glucose, amino acids and fatty acids, by an increase in the cytoplasmic free Ca2+ concentration ([Ca2+]i), which mediates diverse cellular processes in these cells. Some vanilloid compounds activate the transient receptor potential vanilloid receptor type 1 (TRPV1) channel. Objective We investigated whether -shogaol could trigger Ca2+ signals in the beta-cell. Methods [Ca2+]i was measured from single INS-1E cells by microscope-based fluorometry using fura-2 as the Ca2+ indicator. Results In fura-2 loaded single rat insulinoma INS-1E cells, a widely used model of beta-cell, -shogaol increased [Ca2+]i in a concentration-dependent manner. [Ca2+]i increase by -shogaol was completely blocked when Ca2+ was omitted from the extracellular medium. Capsazepine, an inhibitor of the TRPV1 ion channel completely inhibited the -shogaol-induced [Ca2+]i increase. [Ca2+]i increase obtained by 1 µM -shogaol was greater than that obtained by 10 mM glucose. Moreover, a sub-stimulatory concentration of -shogaol (300 nM), significantly enhanced the glucose-induced [Ca2+]i increase in these cells. Conclusion We conclude that -shogaol induces Ca2+ signals in the beta-cell by activating the TRPV1 channels, and it sensitizes the beta-cells to stimulation by glucose.
Image: -shogaol-induced [Ca2+]i increase.
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Copyright (c) 2014 Paola Rebellato, Md. Shahidul Islam
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