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Antagonism of the behavioral effects of 2,5-dimethoxy-4-methylamphetamine (DOM) and quipazine by metergoline.

Randall L. Commissaris, Richard H. Rech

Pharmacology, Biochemistry, and Behavior October 1981 DOI: 10.1016/0091-3057(81)90227-6 (opens in new tab)

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AI-extracted from the abstract
Characteristics Controlled animal experiment Peer reviewed
Population Food-deprived male rats
Interventions quipazine metergoline
Dose metergoline 1.0 mg/kg and 0.1 mg/kg; DOM increased about 16-fold; quipazine increased about 8-fold
Key findings DOM and quipazine each produced dose-dependent pausing in rats responding on a fixed-ratio-40 food-reinforcement schedule. Metergoline pretreatment at 1.0 mg/kg, and to a lesser extent 0.1 mg/kg, shifted both dose-response curves significantly to the right, and roughly 16-fold higher DOM or 8-fold higher quipazine appeared to override the 1 mg/kg metergoline antagonism. The authors suggest the pausing reflects activation of serotonin receptors.

Abstract

The present study examined the disruptive effects of the phenethylamine hallucinogen 2,5-dimethoxy-4-methylamphetamine (DOM) and the putative 5-hydroxytryptamine (5-HT) agonist quipazine on fixed ratio-40 (FR-40) operant responding alone or after pretreatment with putative 5-HT antagonist metergoline. Food-deprived male rats were trained to bar press on a FR-40 schedule for food reinforcements; control responding under this schedule is characterized by a rapid, constant rate of responding (approximately 100 response/min). In control animals, both DOM and quipazine produced dose-dependent disruptions of FR-40 performance characterized by periods of non-responding or "pausing". Following pretreatment with 1.0 mg/kg, and to a lesser extent 0.1 mg/kg, metergoline (180 min prior to the session) the dose-response curves for the "pausing" produced by both DOM and quipazine were shifted significantly to the right. Moreover, increasing the dose of DOM about 16-fold and that of quipazine about 8-fold appears to completely override the antagonism by 1 mg/kg metergoline. These results suggest that the "pausing" produced by DOM or quipazine is the result of activation of 5-HT receptors.

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