title: [6]-shogaol induces Ca²⁺ signals by activating the TRPV1 channels in the rat insulinoma INS-1E cells.
abstract: BACKGROUND
  [6]-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 [6]-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, [6]-shogaol increased [Ca²⁺](i) in a concentration-dependent manner. [Ca²⁺](i) increase by [6]-shogaol was 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 obtained by 1 µM [6]-shogaol was greater than that obtained by 10 mM glucose. Moreover, a sub-stimulatory concentration of [6]-shogaol (300 nM), significantly enhanced the glucose-induced [Ca²⁺](i) increase in these cells.
  
  
  CONCLUSIONS
  We conclude that [6]-shogaol induces Ca²⁺ signals in the beta-cell by activating the TRPV1 channels, and it sensitizes the beta-cells to stimulation by glucose.
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Research Centre and Department of Medical Biochemistry and Biophysics; Karolinska Institutet. Stockholm, Sweden. paola.rebellato@ki.se.
authors.forename: Paola
authors.initials: P
authors.lastname: Rebellato
authors.forename: Md Shahidul
authors.initials: MS
authors.lastname: Islam
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002396:Catechols / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002999:Clone Cells; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000494:pharmacology; D007340:Insulinoma / Q000473:pathology*; D007515:Islets of Langerhans / Q000187:drug effects; D010190:Pancreatic Neoplasms / Q000473:pathology*; D051381:Rats; D050916:TRPV Cation Channels / Q000819:agonists*
chemical_list: D002396:Catechols; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C040115:shogaol; D005947:Glucose; C071423:capsazepine; D002211:Capsaicin