Influence of social dominance on self-stimulation behavior in male golden hamsters.

The effect of a socially dominant hamster on the self-stimulation behavior of the subordinate hamster was examined. After determining social ranking, six hamsters were trained to press a lever in an operant chamber in which a dominant hamster was presented over a grid wall. The threshold of rewarding effect was evaluated by using a descending series of current intensity as electrical reward. When a dominant hamster was present, the subordinate hamster showed a shift of intensity-response function to the right (higher intensity). The presence of a subordinate hamster did not influence the response in dominant hamsters. Furthermore, beta-carboline (FG-7142) (5, 10, and 20 mg/kg, IP) caused a decrease in rewarding effect in dose-dependant manner. These results suggest that the presence of a dominant animal may have caused "a state of anxiety" somewhat similar to the anxiety caused by the benzodiazepine inverse agonist.