original investigation

Psychopharmacology

, Volume 213, Issue 1, pp 11-18

Effects of acute pramipexole on preference for gambling-like schedules of reinforcement in rats

  • Patrick S. JohnsonAffiliated withDepartment of Applied Behavioral Science, University of Kansas Email author 
  • , Gregory J. MaddenAffiliated withDepartment of Applied Behavioral Science, University of Kansas
  • , Adam T. BrewerAffiliated withDepartment of Applied Behavioral Science, University of Kansas
  • , Jonathan W. PinkstonAffiliated withDepartment of Pharmacology and Toxicology, University of Kansas
  • , Stephen C. FowlerAffiliated withDepartment of Applied Behavioral Science, University of KansasDepartment of Pharmacology and Toxicology, University of Kansas

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Abstract

Rationale

Pramipexole and other direct dopamine agonist medications have been implicated in the development of impulsive behavior such as pathological gambling among those taking the drug to control symptoms of Parkinson’s disease or restless leg syndrome. Few laboratory studies examining pramipexole’s effects on gambling-like behavior have been conducted.

Objectives

The present study used a rodent model approximating some aspects of human gambling to examine within-subject effects of acute pramipexole (0.03, 0.1, 0.18, and 0.3 mg/kg) on rat’s choices to earn food reinforcement by completing variable-ratio (VR; i.e., gambling-like) or fixed-ratio (FR) response requirements.

Results

In a condition in which the VR alternative was rarely selected, all but the lowest dose of pramipexole significantly increased choice of the VR alternative (an average of 15% above saline). The same doses did not affect choice significantly in a control condition designed to evaluate the involvement of nonspecific drug effects. Pramipexole increased latencies to initiate trials (+9.12 s) and to begin response runs on forced-choice trials (VR = +0.21 s; FR = +0.88 s), but did not affect measures of response perseveration (conditional probabilities of “staying”).

Conclusions

The findings are consistent with clinical reports linking pramipexole to the expression of increased gambling in humans. Results are discussed in the context of neurobehavioral evidence suggesting that dopamine agonists increase sensitivity to reward delay and disrupt appropriate feedback from negative outcomes.

Keywords

Pramipexole Dopamine agonist Gambling Impulsive behavior Parkinson’s disease Rat