Methylphenidate as a reinforcer for rats: Contingent delivery and intake escalation

Julie A. Marusich, Joshua S. Beckmann, Cassandra Gipson-Reichardt, Michael T. Bardo

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Methylphenidate (MPH) is one of the most widely prescribed drugs for treating attention-deficit hyperactivity disorder. Previous research suggested that MPH is a reinforcer for rats, but not all of the manipulations to show that lever pressing is controlled by the contingency to obtain MPH have been examined. In Experiment 1, responding for MPH on a progressive ratio (PR) schedule was assessed. Rats self-administered varying doses of MPH (0.056-1.0 mg/kg/infusion) on a PR schedule of reinforcement, and self-administered more MPH than saline, with maximal responding occurring at a unit dose of 0.56 mg/kg/infusion. Experiment 2 examined if there were differences in responding between contingent and noncontingent MPH (0.56 mg/kg/infusion) on a fixed ratio schedule of reinforcement. Results showed that rats responded for contingent MPH, and that responding was not maintained when MPH was delivered noncontingently. Experiment 3 examined self-administration of MPH (0.1 or 0.3 mg/kg/infusion) during long access (6 hr) compared to short access sessions (1 hr). Results showed that rats given long access to MPH showed an escalation of intake across sessions, with this escalation being more pronounced at the lower unit dose (0.1 mg/kg/infusion); in contrast, rats given short access to MPH did not show an increase in MPH self-administration across sessions at either MPH dose tested. Taken together, these results indicate that MPH is an effective intravenous reinforcer for rats and that, similar to other stimulants such as cocaine, amphetamine and methamphetamine, MPH is subject to abuse as reflected by dysregulated intake across repeated long access sessions.

Original languageEnglish (US)
Pages (from-to)257-266
Number of pages10
JournalExperimental and Clinical Psychopharmacology
Volume18
Issue number3
DOIs
StatePublished - Jun 2010
Externally publishedYes

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Methylphenidate
Reinforcement Schedule
Self Administration
Methamphetamine
Amphetamine
Attention Deficit Disorder with Hyperactivity
Cocaine

Keywords

  • Methylphenidate
  • Noncontingent
  • Progressive ratio
  • Rat
  • Self-administration

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Psychiatry and Mental health

Cite this

Methylphenidate as a reinforcer for rats : Contingent delivery and intake escalation. / Marusich, Julie A.; Beckmann, Joshua S.; Gipson-Reichardt, Cassandra; Bardo, Michael T.

In: Experimental and Clinical Psychopharmacology, Vol. 18, No. 3, 06.2010, p. 257-266.

Research output: Contribution to journalArticle

Marusich, Julie A. ; Beckmann, Joshua S. ; Gipson-Reichardt, Cassandra ; Bardo, Michael T. / Methylphenidate as a reinforcer for rats : Contingent delivery and intake escalation. In: Experimental and Clinical Psychopharmacology. 2010 ; Vol. 18, No. 3. pp. 257-266.
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