Rikkunshito, a Japanese Kampo Medicine, Ameliorates Decreased Feeding Behavior via Ghrelin and Serotonin 2B Receptor Signaling in a Novelty Stress Murine Model

Abstract EN

We investigated the effects of rikkunshito (RKT), a ghrelin signal enhancer, on the decrease in food intake after exposure to novelty stress in mice.

RKT administration (500 mg/kg, per os) improved the decrease in 6 h cumulative food intake.

In control mice, the plasma acylated ghrelin levels significantly increased by 24 h fasting.

In contrast, the acylated ghrelin levels did not increase by fasting in mice exposed to the novelty stress.

RKT administration to the novelty stress mice showed a significant increase in the acylated ghrelin levels compared with that in the distilled-water-treated control mice.

Food intake after administering serotonin 2B (5-HT2B) receptor antagonists was evaluated to clarify the role of 5-HT2B receptor activation in the decrease in feeding behavior after novelty stress.

SB215505 and SB204741, 5-HT2B receptor antagonists, significantly improved the decrease in food intake after exposure to novelty stress.

A component of RKT, isoliquiritigenin, prevented the decrease in 6 h cumulative food intake.

Isoliquiritigenin showed 5-HT2B receptor antagonistic activity in vitro.

In conclusion, the results suggested that RKT improves the decrease in food intake after novelty stress probably via 5-HT2B receptor antagonism of isoliquiritigenin contained in RKT.