从5-HT和P物质探讨小半夏汤防治化疗性恶心呕吐的机制

Chemotherapy-induced nausea and vomiting (CINV) is a common and distressing side-effect in patients receiving anticancer chemotherapeutic drugs such as cisplatin, and is a major reason for non-complicance with cancer treatment. There are much evidence to confirm the pharmacological pivotal roles of 5-HT and substance P (SP), particularly 5-HT3 receptors and NK1 receptors in the control of anticancer drug-induced emesis. Xiaobanxia Decoction (XD) is a traditional Chinese anti-emetic prescription recording in JinGuiYaoLue, a traditional Chinese medicinal classic written by Zhang Zhongjing nearly two thousand years ago. XD is composed of two kinds of crude Chinese herbs, Pinelliae tuber (Pinellia ternate (Thunb) Breit.) and ginger(Zingiber officinale Roscoe). Clinical studies have proved its potentials of anti-emetic effects, including CINV. In cisplatin-induced rat pica model and mink vomiting model, our previous studies showed XD can suppress CINV, one of the key machenism is decreasing 5-HT level in intestine and brain. Other reportings confirmed its potentials of depressing CINV and suggested that decreasing SP is also a important part of its anti-emetic mechanism. Basing on our previous research results and other reportings, we predict that suppressing 5-HT and SP is the pivotal machenism underlying XD's anti-emetic effect. But until now, the precise mechanism and roles of 5-HT and SP underlying the anti-emetic mechanism of XD has not been elucidated. In the present project, we will explore the anti-emetic mechanism of XD focusing on 5-HT and SP as well as 5-HT3 receptors and NK1 receptors. In our potocol, we will observe the effect of XT on 5-HT and SP concentration both in brainstem and intestine using HPLC-ECD method in cisplatin induced rat pica model, and observe the synthesis, storage, transport, and metabolite of 5-HT using immunohistochemistry staining and RT-PCR methods. We will observe the suppressing effect on acute and delayed phase of CINV in selective 5-HT3 receptor agonist and NK1 receptor agonist induced pica model in rats, respectively. We will also explore the antagonizing effect on 5-HT3 receptors and NK1 receptors by observing abdominal afferent vagus activity in rats, observing [Ca2+]i in HEK293-5-HT3R cells and HEK293-NK1R cells, and observing contraction of guinea pig ileum in organ bath. Above all, the present project will not only make clear the anti-emetic mechanism of XD focusing on the pivotal neurotransmitters 5-HT and SP, but also be facilitated in modernizing traditional Chinese herbs.

恶心呕吐是肿瘤化疗最常见不良反应之一，甚至成为化疗失败的原因。小半夏汤出自《金匮要略》，为止呕方之祖，防治化疗呕吐疗效确切，但具体机制不清。我们根据工作基础和文献，认为：干预5-HT和5-HT3受体、P物质和NK1受体是其防治化疗呕吐的关键机制。其作用部位涉及中枢和外周，是多靶点、多环节、多机制综合作用的结果。 本项目拟在前期工作基础上，针对化疗呕吐病理机制的关键神经递质5-HT和P物质，从整体动物、离体组织、细胞、分子、基因等水平，从中枢和外周，从行为学、功能和形态等方面，采用传统药理学与现代分子生物学相结合的实验方法，选择调控5-HT的合成酶、转运体、代谢酶等关键调控因素，同步观察5-HT合成、释放、转运、代谢和5-HT3受体、P物质及其前体和NK1受体在化疗呕吐发生发展过程中的动态变化，系统深入阐明小半夏汤防治化疗呕吐的作用靶点和机制，对于中西医结合肿瘤治疗和中药现代化均具有重要意义

小半夏汤防治化疗性恶心呕吐（chemotherapy-induced nausea and vomiting，CINV）疗效确切，但机制不清。在前期工作基础上，针对CINV病理机制的关键神经递质及其相应受体，从整体动物、离体组织、细胞、分子和基因等水平，较深入阐明了小半夏汤防治CINV的作用靶标和机制，超额完成了研究任务，达到了预期研究目标。.1．针对CINV病理机制的关键神经递质5-HT、P物质以及多巴胺（DA），以顺铂建立化疗性大鼠异食癖恶心呕吐模型，从外周和中枢、同步、动态观察了小半夏汤对化疗大鼠5-HT合成、代谢、转运和5-HT3A受体、P物质及其前体PPT和NK1受体、DA合成、代谢和D2受体的影响。结果表明，小半夏汤对CINV急性期和延迟期均有防治作用；对CINV急性期的防治作用机制主要与抑制回肠和延髓5-HT合成、促进5-HT代谢以及下调5-HT3A受体mRNA和蛋白表达有关；对CINV延迟期的作用机制主要与抑制回肠和延髓P物质合成以及下调NK1受体mRNA和蛋白表达有关；对CINV的防治作用还与抑制回肠和延髓DA合成以及下调D2受体mRNA和蛋白表达有关。说明小半夏汤防治CINV的作用机制与对5-HT、P物质、DA三种神经递质及其相应受体的多靶点、多环节调控作用有关。.2．利用5-HT3R和NK1R激动剂和拮抗剂等工具药，采用5-HT3R和NK1R激动剂分别诱导的大鼠异食癖模型、大鼠腹部迷走神经放电、豚鼠离体肠管实验和NG108-15细胞[Ca2+]i检测等四个不同层次的实验方法，研究结果表明，小半夏汤及其主要组分可以拮抗5-HT3受体和NK1受体，这可能是小半夏汤防治CINV的重要机制之一。.3．小半夏汤防治CINV机制非常复杂，随着研究的拓展和深入，又从其它方面对其止吐机制进行了初步探索，发现小半夏汤防治CINV还与改善化疗所致的胃肠激素水平紊乱、胃肠运动异常以及胃肠黏膜损伤有关。.本项目已发表学术论文17篇，尚有部分论文正在整理或投稿中，培养硕士和博士研究生10名，已毕业7名。.总之，本项目针对CINV的关键神经递质，系统深入地研究了小半夏汤防治CINV的作用靶点和作用机制，部分揭示了“止呕之祖方”小半夏汤止吐的现代科学内涵，对于中西医结合肿瘤治疗和中药现代化均具有重要意义。