Appetite loss or anorexia substantially decreases the quality of life in patients with cancer, depression and gastrointestinal disorders, and can lead to sarcopenia and frailty. Foods that restore appetite have been sought-for but are not currently available. Historically, onion intake was adopted to treat a variety of diseases with reduced appetite including cancer and gastrointestinal disturbances. While isoalliin is a core component of onion, the effects of isoalliin on feeding behavior and feeding centers remain unknown. Neuropeptide Y (NPY) and ghrelin are the most potent central and peripheral inducers of appetite. A Japanese kampo medicine Ninjin'yoeito activates ghrelin-responsive NPY neurons in the hypothalamic arcuate nucleus (ARC) and counteracts anorexia induced by an anti-cancer drug cisplatin. This study explored the effects of isoalliin on feeding behavior and activities of ARC neurons in mice. Isoalliin, injected intraperitoneally, dose-dependently increased food intake during dark phase (DP) and daily without altering light phase (LP) food intake. We measured cytosolic Ca²⁺ concentration ([Ca²⁺]_i) in single ARC neurons including NPY neurons identified by GFP fluorescence. Isoalliin increased [Ca²⁺]_i in 10 of 18 (55.6%) NPY neurons, a majority of which also responded to ghrelin with [Ca²⁺]_i increases, indicating that the ARC ghrelin-responsive NPY neuron is the major target of isoalliin. Isoalliin also increased [Ca²⁺]_i in the ARC neurons that responded to Ninjin'yoeito. These results indicate that isoalliin enhances feeding at the active period and activates ARC ghrelin-responsive NPY neurons and Ninjin'yoeito-responsive neurons. These abilities of isoalliin to stimulate DP feeding and activate ARC orexigenic neurons provide scientific evidence for the health beneficial effects of onion experienced historically and globally.

食欲减退或厌食会显着降低癌症、抑郁症和胃肠道疾病患者的生活质量，并可能导致肌肉减少和虚弱。恢复食欲的食物一直在寻找，但目前还没有。从历史上看，洋葱的摄入量被用来治疗多种食欲下降的疾病，包括癌症和胃肠道疾病。虽然异蒜素是洋葱的核心成分，但异蒜素对摄食行为和摄食中心的影响仍然未知。神经肽 Y (NPY) 和生长素释放肽是最有效的中枢和外周食欲诱导剂。日本汉方药 Ninjin'yoeito 激活下丘脑弓状核 (ARC) 中的 ghrelin 反应性 NPY 神经元，并抵消由抗癌药物顺铂引起的厌食症。本研究探讨了异蒜素对小鼠 ARC 神经元摄食行为和活动的影响。腹腔注射异蒜素，在暗期 (DP) 和每天的食物摄入量呈剂量依赖性增加，而不会改变亮期 (LP) 的食物摄入量。我们测量了细胞溶质 Ca^{单个 ARC 神经元中的2+}浓度 ([Ca ²⁺ ] _i )，包括通过 GFP 荧光识别的 NPY 神经元。异蒜素在 18 个 (55.6%) NPY 神经元中的 10 个中增加 [Ca ²⁺ ] _i，其中大多数也对 ghrelin 有反应， [Ca ²⁺ ] _i增加，表明 ARC ghrelin 响应 NPY 神经元是主要目标异蒜素。异蒜素也增加了 [Ca ²⁺ ] _i在对 Ninjin'yoeito 做出反应的 ARC 神经元中。这些结果表明异蒜素增强了活跃期的摄食并激活了ARC ghrelin 响应性NPY 神经元和Ninjin'yoeito 响应性神经元。异蒜素刺激 DP 喂养和激活 ARC 促食欲神经元的这些能力为历史上和全球所经历的洋葱对健康有益的影响提供了科学证据。