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MDMA and performance under a progressive-ratio schedule of water delivery

Sean Laraway1, Susan Snycerski, Alan Poling

  • 1Department of Psychology, Western Michigan University, Kalamazoo, MI 49008-5439, USA.

Experimental and Clinical Psychopharmacology
|November 6, 2003
PubMed

Insights

This study found that higher doses of MDMA (ecstasy) decreased motivation in rats seeking water. The drug did not enhance the reinforcing effects of water, suggesting motor activity changes may explain the results.

Area of Science:

  • Neuroscience
  • Behavioral Pharmacology

Background:

  • The reinforcing efficacy of drugs is often studied using operant conditioning paradigms.
  • Previous research suggested MDMA might increase the reinforcing properties of natural rewards like water.

Purpose of the Study:

  • To investigate the motivational effects of MDMA (ecstasy) on water-seeking behavior in rats.
  • To determine if MDMA enhances the reinforcing efficacy of water under a progressive-ratio schedule.

Main Methods:

  • Rats were trained to lever-press for water on a progressive-ratio 2 schedule.
  • Rats were administered various doses of MDMA (0, 1.0, 1.8, 3.2, 5.6 mg/kg) or vehicle.
  • Water restriction levels were manipulated to assess their impact on response measures.

Main Results:

  • Lower MDMA doses (1.0, 1.8 mg/kg) had inconsistent effects on breakpoints and response rates.
  • Higher MDMA doses (3.2, 5.6 mg/kg) significantly decreased breakpoints and response rates.
  • Increased water restriction increased response measures, while decreased restriction decreased them.
  • No evidence was found that MDMA increased the reinforcing efficacy of water.

Conclusions:

  • MDMA, particularly at higher doses, appears to decrease, rather than increase, the motivation to seek water.
  • The observed effects may be attributable to MDMA-induced alterations in motor activity.
  • The findings contradict previous suggestions that MDMA enhances the reinforcing efficacy of natural rewards.

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