[6]-Shogaol Induces Ca2+ Signals by Activating the TRPV1 Channels in the Rat Insulinoma INS-1E Cells

摘要

Context [6]-shogaol is a vanilloid compound presentin steamed ginger (Zingiber officinale), a commonly used spice. Pancreaticbeta-cells respond to nutrients like glucose, amino acids and fatty acids, by anincrease in the cytoplasmic free Ca2+ concentration ([Ca2+]i),which mediates diverse cellular processes in these cells. Some vanilloid compoundsactivate the transient receptor potential vanilloid receptor type 1 (TRPV1) channel.Objective We investigated whether [6]-shogaol could trigger Ca2+signals in the beta-cell. Methods [Ca2+]i was measuredfrom 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, awidely used model of beta-cell, [6]-shogaol increased [Ca2+]iin a concentration-dependent manner. [Ca2+]i increase by [6]-shogaolwas completely blocked when Ca2+ was omitted from the extracellular medium.Capsazepine, an inhibitor of the TRPV1 ion channel completely inhibited the [6]-shogaol-induced[Ca2+]i increase. [Ca2+]i increase obtainedby 1 μM [6]-shogaol was greater than that obtained by 10 mM glucose. Moreover, asub-stimulatory concentration of [6]-shogaol (300 nM), significantly enhanced theglucose-induced [Ca2+]i increase in these cells. ConclusionWe conclude that [6]-shogaol induces Ca2+ signals in the beta-cell byactivating the TRPV1 channels, and it sensitizes the beta-cells to stimulation byglucose.