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Psychopharmacology (Berl). 2006 Mar;184(3-4):391-400. Epub 2005 Oct 25.

Dissociating the primary reinforcing and reinforcement-enhancing effects of nicotine using a rat self-administration paradigm with concurrently available drug and environmental reinforcers.

Author information

1
Department of Psychology, University of Pittsburgh, 3137 Sennott Square, 210 S. Bouquet St., Pittsburgh, PA 15260, USA. mip16@pitt.edu

Abstract

RATIONALE:

Nicotine has two effects on reinforcement in traditional self-administration paradigms. It serves as a primary reinforcer by increasing the probability of behaviors that result in nicotine delivery. However, nicotine also potently enhances behaviors that result in the delivery of nonpharmacological reinforcers.

OBJECTIVES:

The present study sought to dissociate these two effects of nicotine on reinforcement.

METHODS:

For one group of rats (2 lever), a nonpharmacological reinforcer [visual stimulus (VS)] was available for pressing one lever. Nicotine infusions were available for pressing a different lever. A second group (NIC + VS) received more traditional self-administration training; both the VS and nicotine were delivered for pressing a single active lever. Control groups received either nicotine infusions (NIC only) or VS presentations (VS only) for pressing the active lever.

RESULTS:

Nicotine alone was a weak reinforcer; the VS alone was slightly more reinforcing than nicotine. When these two reinforcers were combined (NIC + VS), response rates were synergistically increased. For the 2-lever group, responding on the nicotine lever was weak, matching the response rates of rats receiving nicotine alone. However, responding on the VS lever was potently enhanced in this group; equaling the response rates for rats receiving both reinforcers for making a single response (NIC + VS).

CONCLUSIONS:

These data indicate that the reinforcement-enhancing effects of nicotine are very potent even when only moderate quantities of the drug are self-administered. Moreover, they provide the first demonstration that the reinforcement-enhancing and primary reinforcing effects of nicotine can be dissociated behaviorally.

PMID:
16249908
DOI:
10.1007/s00213-005-0183-4
[Indexed for MEDLINE]

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