"Bupropion can serve as a discriminative stimulus (S-D) in an operant drug discrimination task, and a variety of stimulants substitute for the bupropion S-D. There are no reports, however, of bupropion functioning as a Pavlovian occasion setter (i.e. feature positive modulator)," scientists writing in the journal Addiction Biology report (see also Addiction Research).

"The present experiment seeks to fill this gap in the literature by training bupropion in rats as a feature positive modulator that disambiguates when a light will be paired with sucrose. Specifically, on bupropion (10 mg/kg intraperitoneal) sessions, offset of 15-second cue lights were followed by brief delivery of liquid sucrose; saline sessions were similar except no sucrose was available. Rats readily acquired the discrimination with more conditioned responding to the light on bupropion sessions. Bupropion is approved for use as a smoking cessation aid, and more recently has drawn attention as a potential pharmacotherapy for Cocaine and Methamphetamine abuse. Accordingly, after discrimination training, we tested the ability of Cocaine (1-10 mg/kg), Methamphetamine (0.1 to 1 mg/kg) and nicotine (0.00625 to 0.2 mg/kg) to substitute for the bupropion feature. Nicotine (0.05 mg/kg) and Methamphetamine (0.3 mg/kg) substituted fully for bupropion; Cocaine did not substitute. These results extend previous research on shared stimulus properties between bupropion and other stimulants to a Pavlovian occasion setting function. Further, this is the first report of nicotine and Methamphetamine substitution for bupropion," wrote J.L. Wilkinson and colleagues, University of Nebraska.

The researchers concluded: "The overlap in stimulus properties might explain the effectiveness of bupropion as a smoking cessation aid and highlight the possible utility of bupropion for treatment of stimulant use disorder."

Wilkinson and colleagues published their study in Addiction Biology (Pavlovian drug discrimination with bupropion as a feature positive occasion setter: substitution by Methamphetamine and nicotine, but not cocaine. Addiction Biology, 2009;14(2):165-173).

Additional information can be obtained by contacting R.A. Bevins, University of Nebraska, Dept. of Psychology, 238 Burnett Hall, Lincoln, NE 68588, USA.