Competition for sucrose-pellets in triads of male Wistar rats: effects of three serotonergic drugs.

1. Within triads of rats, individuals can be discerned according to their competition for sucrose-pellets as a high-, a medium- and a poor-performing animal. 2. The competition-rates, expressed as scores, are affected by serotonergic drugs: upon inhibiting tryptophan-hydroxylase, the characteristic abstention of the poor-performing rats can temporarily be overcome; quipazine, on the other hand, leads to a dose-dependent decrease in the competition-rate of high-performing rats. 3. Such findings are indicative for a regulatory effect of some serotonergic mechanisms on a competition-behavior evoked within the familiar social context.