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薬理と治療
Abstract
Background The present study was conducted to investigate effect of ninjinyoeito on the motivation of orexigenic or nesting behaviors in repeated water immersed(WI)mice. Methods Ninjinyoeito(NYT, 1.5 g╱kg, PO)or with co-administration of dopamine D2 receptor antagonist(metoclopramide, 10 mg╱kg, IP)was administered to repeated WI model mice. We measured 1, 4, 8, and 24︱h cumulative food intake, 24-h nesting score, and used nest materials following final WI. In addition, effects of ingredients in NYT on dopamine metabolism-related enzymes were determined in the in vitro assay. Results WI resulted in a decrease in 4, 8, 24-h cumulative food intake, 24-h nesting score, and used nest materials. Additionally, the reduced food intake and nesting behavior by WI were increased by administrating NYT. The effect of NYT on food intake and nesting score was completely abolished with co-administration of dopamine D2 receptor antagonist and attenuated in pair-fed mice that was restricted to food intake of WI treated control mice. Moreover, monoamine-oxidase B inhibitory action by calycosin(IC50;3.17μmol╱L), catechol-O-Methy-transferase inhibitory action by onjixanthone II(IC50;1.02μmol╱L), or dopamine transporter inhibitory action by onjisaponin B(IC50;1.16μmol╱L)was found using in vitro assay. Conclusion Our results indicated that administration of NYT to repeated WI mice prevented the decrease in motivation of goal-directed behaviors in this model via dopamine D2 receptor activation.
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