5,7,3′,4′—Tetramethoxyflavone, a Component of Kaempferia parviflora, Facilitates Sympathetic Nerve Innervating Brown Adipose Tissue

Objectives　Kaempferia parviflora（KP）was discovered in Thailand. It has been used widely as a herbal medicine for centuries. KP and its various components have been suggested to exhibit beneficial effects such as anti-obesity, anti-inflammatory, and antioxidant effects. We aimed to focus on its effect on the brown adipose tissue （BAT）, which consumes energy due to thermogenesis. We examined the effect of intraduodenal（ID）administration of a KP extract （KPE）on the activity of the sympathetic nerve innervating BAT in urethane-anesthetized rats. We also identified one of components from KPE responsible for the effects on BAT-sympathetic nerve activity（BAT-SNA）and investigated the effects of this component on BAT-SNA and BAT-temperature（BAT-T）in rats. Methods　The present study examined the effects of ID administration of KPE and fractions on autonomic neurotransmission in anesthetized rats by electrophysiological method. We did fractionation of the fractions containing methoxyflavones from KPE using high-performance liquid chromatography. We measured of BAT-T using by thermistor implantable telemetry system. Results　ID administration of original KPE significantly elevated the BAT-SNA in urethane-anesthetized rats. Among the six fractions of methoxyflavones isolated from KPE, ID administration of fraction 2 containing 5,7,3′,4′-tetramethoxyflavone and 3,5,7,3′,4′- pentamethoxyflavone caused an increase in BAT-SNA in rats. Moreover, ID administration of 5,7,3′,4′-tetramethoxyflavone resulted an increase temperature in the subcutaneous space above the interscapular BAT in conscious rats. Conclusions　These findings suggest that 5,7,3′,4′-tetramethoxyflavone, a component of KP, stimulates thermogenesis via excitation of the sympathetic nerve innervating BAT.