Some effects of chlorimipramine and imipramine on the schedule-controlled behavior of the pigeon.

The effects of imipramine and chlorimipramine on schedule-controlled behavior were compared by examining the effects of both drugs on the performance of pigeons under a multiple fixed-interval 600-s fixed-ratio 30-response (mult FI 600 FR 30) schedule of grain presentation and under a mult FI 200 FI 200 schedule in which responding in one component was punished. Imipramine decreased the rate of FR 30 responding at slightly lower doses than or the same doses as those needed to decrease the rate of FI 600 responding. In contrast, chlorimipramine decreased the rate of FI 600 responding at lower doses than those needed to decrease the rate of FR responding. These effects of chlorimipramine were similar to those of chlorpromazine subsequently determined in the same pigeons. Imipramine and chlorimipramine increased proportionally more or decreased proportionally less the lower rates of responding during the first half of the FI 600 than the higher rates of responding during the second half. When the effects of imipramine or chlorimipramine on performance under the mult FI 200 FI 200 schedule were determined, both imipramine and chlorimipramine affected the rates of punished responding and unpunished responding similarly. Thus, while some effects of chlorimipramine on the schedule-controlled behavior of the pigeon are similar to the effects of imipramine, other effects of chlorimipramine more strongly resemble those of chlorpromazine in the pigeon.