Comparative neuropharmacology of N-(2-methoxybenzyl)-2,5-dimethoxyphenethylamine (NBOMe) hallucinogens and their 2C counterparts in male rats

2,5-Dimethoxyphenethylamines (2C compounds) are 5-HT_2A/2C receptor agonists that induce hallucinogenic effects. N-methoxybenzylation of 2C compounds markedly increases their affinity for 5-HT_2A receptors, and two such analogs, 2-(4-chloro-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25C-NBOMe) and 2-(4-iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe), have emerged in recreational drug markets. Here, we investigated the neuropharmacology of 25C-NBOMe and 25I-NBOMe in rats, as compared to their 2C analogs and the prototypical 5-HT_2A/2C agonist 1-(4-iodo-2,5-dimethoxyphenyl)propan-2-amine (DOI). Compounds were tested in vitro using 5-HT_2A receptor binding and calcium mobilization assays. For in vivo experiments, 25C-NBOMe (0.01-0.3 mg/kg), 25I-NBOMe (0.01-0.3 mg/kg), 2-(4-chloro-2,5-dimethoxyphenyl)ethanamine (2C-C) (0.1-3.0 mg/kg), 2-(4-iodo-2,5-dimethoxyphenyl)ethanamine (2C-I) (0.1-3.0 mg/kg) and DOI (0.03-1.0 mg/kg) were administered subcutaneously (sc) to male rats, and 5-HT_2A-mediated behaviors were assessed. NBOMes displayed higher affinity for 5-HT_2A receptors than their 2C counterparts but were substantially weaker in functional assays. 25C-NBOMe and 25I-NBOMe were much more potent at inducing wet dog shakes (WDS) and back muscle contractions (BMC) when compared to 2C-C and 2C-I. Pretreatment with the selective 5-HT_2A antagonist (R)-(2,3-dimethoxyphenyl){1-[2-(4-fluorophenyl)ethyl]-4-piperidinyl}methanol (M100907) reversed behaviors produced by all agonists. Interestingly, binding affinities at the 5-HT_2A receptor were significantly correlated with potencies to induce BMC but not WDS. Our findings show that NBOMes are highly potent 5-HT_2A agonists in rats, similar to effects in mice, and consistent with the reported hallucinogenic effects in human users.
Elmore, J. S., Decker, A. M., Sulima, A., Rice, K. C., Partilla, J. S., Blough, B. E., & Baumann, M. H. (2018). Comparative neuropharmacology of N-(2-methoxybenzyl)-2, 5-dimethoxyphenethylamine (NBOMe) hallucinogens and their 2C counterparts in male rats. Neuropharmacology. 10.1016/j.neuropharm.2018.02.033
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