N‐Isopropylbenzylamine‐induced conditioned place preference, sensitization behaviour and self‐administration in rodents

Abstract

N‐Isopropylbenzylamine (N‐ipb), a chain isomer of methamphetamine (METH) with similar physical properties, has been used as a substitute for METH in seized drug samples. However, the abuse potential of N‐ipb remains unclear. Therefore, this study aimed to evaluate the abuse potential of N‐ipb in comparison to METH, by using conditioned place preference (CPP), locomotor sensitization and intravenous self‐administration tests. The results showed that N‐ipb at a dose of 3 mg·kg−1 significantly induced CPP in mice, which was comparable to the effect of METH at 1 mg·kg−1. Either acute or repeated N‐ipb injections (1 or 3 mg·kg−1) failed to raise the locomotor activity. However, acute treatment with 10 mg·kg−1 N‐ipb elevated the locomotor activity compared with saline, while chronic injection of 10 mg·kg−1 N‐ipb induced a delayed and attenuated sensitization compared with 1 mg·kg−1 METH. Rats could acquire N‐ipb self‐administration at a dose of 1 mg·kg−1·infusion−1, and a typical inverted U‐shaped dose–response curve was obtained for N‐ipb. The mean dose of N‐ipb that maintained the maximum response was greater than that of METH, indicating that N‐ipb is less potent for reinforcement than METH. In the economic behavioural analysis, comparison of essential values derived from the demand elasticity revealed that N‐ipb is less efficacy as a reinforcer than METH. The present data demonstrate that N‐ipb functions as a reinforcer and has a potential for abuse. However, the potency of psychomotor stimulation and the reinforcing effectiveness of N‐ipb are lower than those of METH.