Methamphetamine-like discriminative stimulus effects of bupropion and its two hydroxy metabolites in male rhesus monkeys

Behav Pharmacol. 2016 Apr;27(2-3 Spec Issue):196-203. doi: 10.1097/FBP.0000000000000224.

Abstract

The dopamine transporter (DAT) inhibitor and nicotinic acetylcholine (nACh) receptor antagonist bupropion is being investigated as a candidate 'agonist' medication for methamphetamine addiction. In addition to its complex pharmacology, bupropion also has two distinct pharmacologically active metabolites. However, the mechanism by which bupropion produces methamphetamine-like 'agonist' effects remains unknown. The aim of the present study was to determine the role of DAT inhibition, nACh receptor antagonism, and the hydroxybupropion metabolites in the methamphetamine-like discriminative stimulus effects of bupropion in rhesus monkeys. In addition, varenicline, a partial agonist at the nACh receptor, and risperidone, a dopamine antagonist, were tested as controls. Monkeys (n=4) were trained to discriminate 0.18 mg/kg intramuscular methamphetamine from saline in a two-key food-reinforced discrimination procedure. The potency and time course of methamphetamine-like discriminative stimulus effects were determined for all compounds. Bupropion, methylphenidate, and 2S,3S-hydroxybupropion produced full, at least 90%, methamphetamine-like effects. 2R,3R-Hydroxybupropion, mecamylamine, and nicotine also produced full methamphetamine-like effects, but drug potency was more variable between monkeys. Varenicline produced partial methamphetamine-like effects, whereas risperidone did not. Overall, these results suggest DAT inhibition as the major mechanism of the methamphetamine-like 'agonist' effects of bupropion, although nACh receptor antagonism appeared, at least partially, to contribute. Furthermore, the contribution of the 2S,3S-hydroxybupropion metabolite could not be completely ruled out.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antidepressive Agents, Second-Generation / metabolism
  • Antidepressive Agents, Second-Generation / pharmacology*
  • Bupropion / metabolism*
  • Bupropion / pharmacology*
  • Central Nervous System Stimulants / pharmacology*
  • Conditioning, Operant / drug effects
  • Discrimination Learning / drug effects*
  • Dopamine Antagonists / pharmacology
  • Dose-Response Relationship, Drug
  • Macaca mulatta
  • Male
  • Methamphetamine / pharmacology*
  • Nicotine / pharmacology
  • Nicotinic Agonists / pharmacology
  • Reinforcement, Psychology
  • Risperidone / pharmacology
  • Time Factors
  • Varenicline / pharmacology

Substances

  • Antidepressive Agents, Second-Generation
  • Central Nervous System Stimulants
  • Dopamine Antagonists
  • Nicotinic Agonists
  • Bupropion
  • Methamphetamine
  • Nicotine
  • Risperidone
  • Varenicline