Effects of stimulants, anorectics, and related drugs on schedule-controlled behavior

R. Adron Harris, Diane Snell, Horace H. Loh

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


The effects of nine drugs were studied in rats responding under either fixed-ratio 30 (FR-30) or fixed-interval 2-min (FI-2) schedules of food presentation. All the drugs decreased average rates of responding under both schedules in a dose-related manner, with apomorphine and clonidine being the most potent and caffeine the least potent. d-Amphetamine was about three times more potent than l-amphetamine in decreasing responding under the FR schedule, while the two isomers were equipotent in reducing the average response rates under the FI schedule. A 10 mg/kg dose of fenfluramine decreased responding for two to three days after administration, but this treatment did not produce long-lasting changes in control performance or in the effects of the serotonergic drugs quizapine and d-paramethoxyamphetamine. The effects of the drugs on the local rates of responding during the FI may be divided into three categories: (1) those drugs that increased low rates of responding and decreased high rates of responding (rate-dependent effects) at dosages that did not markedly decrease the average response rates (d-amphetamine, methylphenidate, and cocaine); (2) those that produced rate-dependent effects only at dosages that markedly reduced average response rates (fenfluramine, quipazine, and clonidine); and (3) those that did not produce clear rate-dependent effects at any dose tested (l-amphetamine, apomorphine, and caffeine). These behavioral results are discussed in relation to their known biochemical effects on brain catecholamine and serotonin systems.

Original languageEnglish (US)
Pages (from-to)49-55
Number of pages7
Issue number1
StatePublished - Jan 1978
Externally publishedYes


  • Apomorphine
  • Caffeine
  • Clonidine
  • Cocaine
  • Fenfluramine
  • Methylphenidate
  • Quipazine
  • Rate-dependence
  • Schedule-controlled behavior
  • d-Amphetamine
  • l-amphetamine


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