硫激肽及其受体抑制褐飞虱取食的分子机制

The brown planthopper, Nilaparvata lugens, is one of the most economically important pests of rice. It has developed high-level of resistance to many kinds of insecticides. Therefore, it is urgent to develop insecticides with novel modes of action to control this pest. Insect G-protein coupled receptors (GPCRs) have important roles in modulating physiology and behaviour. Pharmacologists have focused their attention on the GPCRs, which are believed to represent promising targets for new insecticides. Sulfakinin (SK) is an insect neuropeptide that constitutes an important component of the neural factors that regulate feeding and digestion. The key modulating functions of SK are mediated by binding and signaling via sulfakinin receptor (SKR). SKR belongs to rhodopsin-like GPCR. It was shown by our previous experiments that the gene expression of nsk was strongly up-regulated in response to feeding and injection of sNSKⅡ demonstrate reduction of food intake in the brown planthopper. However, the molecular mechanisms of NSK/NSKR inhibition of food intake in the brown planthopper is unknown. In this proposal, we will illustrate this mechanism at behavioral, biochemical, cellular and molecular levels on the basis of ethological, genetic, immunological, cell biological and pharmacological methods. We believe this research will enrich the contents of the insect physiology and provide valuable information for developing new pesticides which target on SK/SKR system.

褐飞虱是为害水稻的重要害虫，已对多种杀虫剂产生抗性，生产上急需开发出新型作用机理的杀虫剂用于其田间防治。G蛋白偶联受体（GPCRs）调控着昆虫的各种生理与行为过程，研究昆虫GPCRs的药理及生理功能可为新型杀虫剂作用靶标研发提供依据。硫激肽（Sulfakinin, SK）在调控昆虫取食中扮演重要角色，其通过结合硫激肽受体（Sulfakinin Receptor, SKR）发挥作用，SKR即为典型的GPCRs家族成员。实验室前期研究发现，褐飞虱在饱腹状态时，硫激肽基因表达量明显上升，且注射硫激肽能够显著抑制褐飞虱取食，但硫激肽及其受体抑制褐飞虱取食的分子机制未知。本研究拟采用行为学、遗传学、免疫学、细胞生物学以及药理学等手段，从行为、生化、细胞到分子层面阐明硫激肽及其受体抑制褐飞虱取食的分子机制。本研究可丰富昆虫生理学研究内容，亦可为作用于昆虫硫激肽及其受体系统的新型杀虫剂研发提供依据。

硫激肽（sulfakinins, SKs）是昆虫神经肽家族中的重要一员，与脊椎动物中的胃泌素（gastrin）和胆囊收缩素（cholecystokinin）类似。对SK的研究主要集中在调控昆虫取食行为上，取食是一种复杂的先天性行为，对动物的生存和生殖至关重要，昆虫需要整合外在环境信息和内部生理需求、神经调节状态以及取食抉择等信息来完成这一行为。SK作为一种经典的饱腹信号主要存在于昆虫脑中，通过激活其硫激肽受体（sulfakinin receptor, SKR）发挥作用。硫激肽受体是典型的G蛋白偶联受体，并被认为是新型杀虫剂开发的理想靶标而受到广泛关注。本研究以农业害虫褐飞虱（Nilaparvata lugens(Stål)）为主要研究对象，首先克隆并明确了褐飞虱硫激肽及其受体基因的时空表达模式和不同营养状态下的表达量差异；建立了稳定的褐飞虱取食行为学研究实验平台和技术，明确了不同类型硫激肽抑制褐飞虱取食的差异；发现了褐飞虱硫激肽参与调节消化酶的生理功能，发现硫激肽可抑制部分消化酶活性和相关消化酶基因表达；通过RNA干扰和对模式生物黑腹果蝇进行遗传学操作，证明了硫激肽作为饱腹信号通过其受体降低了褐飞虱和果蝇甜味受体基因表达进而抑制昆虫取食的分子与神经机制。本研究丰富了昆虫生理学的研究内容，揭示了硫激肽抑制褐飞虱取食的生化与分子机制，为研发高效、高选择性的昆虫取食行为调节剂提供了理论依据和技术支持。