Research ReportsUltra-low doses of the transient receptor potential vanilloid 1 agonist, resiniferatoxin, prevents vomiting evoked by diverse emetogens in the least shrew (Cryptotis parva)Darmani, Nissar A.; Henry, Denise A.; Zhong, Weixia; Chebolu, SeethaAuthor Information Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA Received 19 November 2018 Accepted as revised 17 June 2019 Correspondence to Nissar A. Darmani, PhD, Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 E. Second Street, Pomona, CA 91766-1854, USA, E-mail: firstname.lastname@example.org Behavioural Pharmacology: February 2020 - Volume 31 - Issue 1 - p 3-14 doi: 10.1097/FBP.0000000000000499 Buy Metrics Abstract Published studies have shown that the transient receptor potential vanilloid 1 (TRPV1) receptor agonist, resiniferatoxin (RTX), has pro and antiemetic effects. RTX can suppress vomiting evoked by a variety of nonselective emetogens such as copper sulfate and cisplatin in several vomit-competent species. In the least shrew, we have already demonstrated that combinations of ultra-low doses of RTX and low doses of the cannabinoid CB1/2 receptor agonist delta-9-tetrahydrocannabinol (Δ9-THC) produce additive antiemetic effects against cisplatin-evoked vomiting. In the current study, we investigated the broad-spectrum antiemetic potential of very low nonemetic doses of RTX against a diverse group of specific emetogens including selective and nonselective agonists of serotonergic 5-hydroxytrptamine (5-HT3) receptor (5-HT and 2-Me-5-HT), dopaminergic D2 receptor (apomorphine and quinpirole), cholinergic M1 receptor (pilocarpine and McN-A-343), as well as the selective substance P neurokinin NK1 receptor agonist GR73632, the selective L-Type calcium channel agonist FPL64176, and the sarcoplasmic endoplasmic reticulum calcium ATPase (SERCA) inhibitor thapsigargin. When administered subcutaneously, ultra-low (0.01 µg/kg) to low (5.0 µg/kg) doses of RTX suppressed vomiting induced by the aforementioned emetogens in a dose-dependent fashion with 50% inhibitory dose values ranging from 0.01 to 1.26 µg/kg. This study is the first to demonstrate that low nanomolar nonemetic doses of RTX have the capacity to completely abolish vomiting caused by diverse receptor specific emetogens in the least shrew model of emesis. Copyright © 2020 YEAR Wolters Kluwer Health, Inc. All rights reserved.