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Updated: Jun 5, 2026
A Method for Evaluating the Reinforcing Properties of Ethanol in Rats without Water Deprivation, Saccharin Fading or Extended Access Training
Published on: January 29, 2017
Selective blockade of the orexin-2 receptor attenuates ethanol self-administration, place preference, and
James R Shoblock1, Natalie Welty, Leah Aluisio
1Neuroscience, Johnson & Johnson Pharmaceutical Research & Development, LLC, San Diego, CA 92121, USA. jshobloc@its.jnj.com
Rationale:
Orexin-1 receptor antagonists have been shown to block the reinforcing effects of drugs of abuse and food. However, whether blockade of orexin-2 receptor has similar effects has not been determined. We have recently described the in vitro and in vivo effects of JNJ-10397049, a selective and brain penetrant orexin-2 receptor antagonist.
Objective:
The goal of these studies was to evaluate whether systemic administration of JNJ-10397049 blocks the rewarding effects of ethanol and reverses ethanol withdrawal in rodents. As a comparison, SB-408124, a selective orexin-1 receptor antagonist, was also evaluated.
Methods:
Rats were trained to orally self-administer ethanol (8% v/v) or saccharin (0.1% v/v) under a fixed-ratio 3 schedule of reinforcement. A separate group of rats received a liquid diet of ethanol (8% v/v) and withdrawal signs were evaluated 4 h after ethanol discontinuation. In addition, ethanol-induced increases in extracellular dopamine levels in the nucleus accumbens were tested. In separate experiments, the acquisition, expression, and reinstatement of conditioned place preference (CPP) were evaluated in mice.
Results:
Our results indicate that JNJ-10397049 (1, 3, and 10 mg/kg, sc) dose-dependently reduced ethanol self-administration without changing saccharin self-administration, dopamine levels, or withdrawal signs in rats. Treatment with JNJ-10397049 (10 mg/kg, sc) attenuated the acquisition, expression, and reinstatement of ethanol CPP and ethanol-induced hyperactivity in mice. Surprisingly, SB-408124 (3, 10 and 30 mg/kg, sc) did not have any effect in these procedures.
Conclusions:
Collectively, these results indicate, for the first time, that blockade of orexin-2 receptors is effective in reducing the reinforcing effects of ethanol.
