A nonpungent component-of steamed ginger-[10]-shogaol-increases adrenaline secretion via the activation of TRPV1

We investigated the components of ginger that are involved in increasing body temperature. Gingerols ([6,8,10]-gingerols) and shogaols ([6,8,10]-shogaols) having different alkyl carbon chain lengths were targeted. All the gingerols and shogaols increased intracellular calcium concentration in rat transient receptor potential vanilloid subtype 1 (TRPV1)-expressing HEK293 cells via TRPV1. In this regard, the shogaols were more potent than the gingerols. Aversive responses were induced by [6]-, (10]-gingerol, and [6]-shogaol (5mmol/l) in rats when these compounds were applied to the eye; however, no response was observed in response to [1,0]-shogaol (5 and 10mmol/l). [10]-Shogaol induced nociceptive responses via TRPVI in rats following its subcutaneous injection into the hindpaw; the pungent compound capsaicin (CAP) and [6]shogaol were observed to have similar effects. Moreover, adrenal catecholamine secretion, which influences energy consumption, was promoted in rats in response to [6]- and [10]-gingerols and [6]- and [10]-shogaols (1.6 mu mol/kg, i.v.). [10] Shogaol-induced adrenaline secretion was inhibited by administration of capsazepine, a TRPV1 antagonist. In conclusion, gingerols and shogaols activated TRPVI and increased adrenaline secretion. Interestingly, [10]-shogaol is the only nonpungent compound among the gingerols and shogaols, suggesting its usefulness as a functional ingredient in food.