Additive antiemetic efficacy of low-doses of the cannabinoid CB_1/2 receptor agonist 螖⁹-THC with ultralow-doses of the vanilloid TRPV1 receptor agonist resiniferatoxin in the least shrew (Cryptotis parva)

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• 作者：Nissar A. Darmani ; Seetha Chebolu ; Weixia Zhong ; Chung Trinh ; Bryan McClanahan ; Rajivinder S. Brar
• 关键词：Least shrew ; Emesis ; Antiemetic ; Cisplatin ; 螖9-THC ; Resiniferatoxin ; Capsaicin ; Ruthenium red ; Capsazepine
• 刊名：European Journal of Pharmacology
• 出版年：5 January, 2014
• 年：2014
• 卷：722
• 期：Complete
• 页码：147-155
• 全文大小：907 K

文摘

Previous studies have shown that cannabinoid CB_1/2 and vanilloid TRPV1 agonists (delta-9-tetrahydrocannabinol (螖⁹-THC) and resiniferatoxin (RTX), respectively) can attenuate the emetic effects of chemotherapeutic agents such as cisplatin. In this study we used the least shrew to demonstrate whether combinations of varying doses of 螖⁹-THC with resiniferatoxin can produce additive antiemetic efficacy against cisplatin-induced vomiting. RTX by itself caused vomiting in a bell-shaped dose-dependent manner with maximal vomiting at 18 渭g/kg when administered subcutaneously (s.c.) but not intraperitoneally (i.p.). 螖⁹-THC up to 10 mg/kg provides only 80% protection of least shrews from cisplatin-induced emesis with an ID₅₀ of 0.3-1.8 mg/kg. Combinations of 1 or 5 渭g/kg RTX with varying doses of 螖⁹-THC completely suppressed both the frequency and the percentage of shrews vomiting with ID₅₀ dose values 5-50 times lower than 螖⁹-THC doses tested alone against cisplatin. A less potent TRPV1 agonist, capsaicin, by itself did not cause emesis (i.p. or s.c.), but it did significantly reduce vomiting induced by cisplatin given after 30 min but not at 2 h. The TRPV1-receptor antagonist, ruthenium red, attenuated cisplatin-induced emesis at 5 mg/kg; however, another TRPV1-receptor antagonist, capsazepine, did not. In summary, we present evidence that combination of CB_1/2 and TRPV1 agonists have the capacity to completely abolish cisplatin-induced emesis at doses that are ineffective when used individually.