Choudhary Shivani, Tipton James G, Abongwa Melanie, Brewer Matthew T, Chelladurai Jeba Jesudoss, Musselman Nicole, Martin Richard J, Robertson Alan P
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA.
Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA.
Invert Neurosci. 2019 Sep 5;19(4):11. doi: 10.1007/s10158-019-0231-0.
Parasitic nematode infections are treated using anthelmintic drugs, some of which target nicotinic acetylcholine receptors (nAChRs) located in different parasite tissues. The limited arsenal of anthelmintic agents and the prevalence of drug resistance imply that future defense against parasitic infections will depend on the discovery of novel targets and therapeutics. Previous studies have suggested that Ascaris suum ACR-16 nAChRs are a suitable target for the development of antinematodal drugs. In this study, we characterized the pharmacology of the Ancylostoma caninum ACR-16 receptor using two-electrode voltage-clamp electrophysiology. This technique allowed us to study the effects of cholinergic agonists and antagonists on the nematode nAChRs expressed in Xenopus laevis oocytes. Aca-ACR-16 was not sensitive to many of the existing cholinomimetic anthelmintics (levamisole, oxantel, pyrantel, and tribendimidine). 3-Bromocytisine was the most potent agonist (> 130% of the control acetylcholine current) on the Aca-ACR-16 nAChR but, unlike Asu-ACR-16, oxantel did not activate the receptor. The mean time constants of desensitization for agonists on Aca-ACR-16 were longer than the rates observed in Asu-ACR-16. In contrast to Asu-ACR-16, the A. caninum receptor was completely inhibited by DHβE and moderately inhibited by α-BTX. In conclusion, we have successfully reconstituted a fully functional homomeric nAChR, ACR-16, from A. caninum, a model for human hookworm infections. The pharmacology of the receptor is distinct from levamisole-sensitive nematode receptors. The ACR-16 homologue also displayed some pharmacological differences from Asu-ACR-16. Hence, A. caninum ACR-16 may be a valid target site for the development of anthelmintics against hookworm infections.
寄生线虫感染通过驱虫药进行治疗，其中一些药物作用于位于寄生虫不同组织中的烟碱型乙酰胆碱受体（nAChRs）。驱虫药种类有限以及耐药性的普遍存在意味着未来对抗寄生虫感染将依赖于发现新的靶点和治疗方法。先前的研究表明，猪蛔虫ACR - 16 nAChRs是开发抗线虫药物的合适靶点。在本研究中，我们使用双电极电压钳电生理学方法对犬钩虫ACR - 16受体的药理学特性进行了表征。该技术使我们能够研究胆碱能激动剂和拮抗剂对非洲爪蟾卵母细胞中表达的线虫nAChRs的影响。犬钩虫ACR - 16（Aca - ACR - 16）对许多现有的拟胆碱驱虫药（左旋咪唑、奥克太尔、噻嘧啶和三苯双脒）不敏感。3 - 溴胞嘧啶是对Aca - ACR - 16 nAChR最有效的激动剂（>对照乙酰胆碱电流的130%），但与猪蛔虫ACR - 16（Asu - ACR - 16）不同，奥克太尔不能激活该受体。Aca - ACR - 16上激动剂脱敏的平均时间常数比在Asu - ACR - 16中观察到的速率更长。与Asu - ACR - 16不同，犬钩虫受体被二氢β - 刺桐碱完全抑制，被α - 银环蛇毒素中度抑制。总之，我们成功地从犬钩虫（一种人类钩虫感染模型）中重组了一种功能完全的同聚体nAChR，即ACR - 16。该受体的药理学特性与对左旋咪唑敏感的线虫受体不同。ACR - 16同源物与Asu - ACR - 16也表现出一些药理学差异。因此，犬钩虫ACR - 16可能是开发抗钩虫感染驱虫药的有效靶点。
