RATIONALE: Current conceptualizations of drug reinforcement assume that drug-taking behavior is a consequence of the contingent, temporal relationship between the behavior and drug reward. However, stimulant drugs also potentiate the rewarding effects of other reinforcers when administered noncontingently. OBJECTIVES: These studies were designed to determine whether noncontingent nicotine enhances the reinforcing properties of a nonpharmacological reinforcer and whether this direct effect facilitates operant behavior within the context of a nicotine self-administration procedure. METHODS: Rats self-administered nicotine or food, or received noncontingent nicotine, saline, or food either with or without a response-contingent, unconditioned reinforcing visual stimulus (VS). RESULTS: Noncontingent nicotine, whether delivered as discrete injections based on a pattern of self-administered nicotine or as a continuous infusion, increased response rates maintained by the VS. There were no significant differences in responding by animals that received contingent compared with noncontingent nicotine when a VS was available. This increase was not observed in the absence of the VS or as a consequence of noncontingent food delivery. Operant behavior was equally attenuated and reinstated by the removal and subsequent replacement of contingent and noncontingent nicotine. Nicotine supported self-administration in the absence of response-contingent, nicotine-paired stimuli; however, response rates were drastically reduced compared with nicotine self-administration with the VS. CONCLUSIONS: Nicotine influences operant behavior in two ways: by acting as a primary reinforcer when it is contingent upon behavior, and by directly potentiating the reinforcing properties of other stimuli through a nonassociative mechanism. Nicotine self-administration and smoking may be largely dependent upon this later action.
RATIONALE: Current conceptualizations of drug reinforcement assume that drug-taking behavior is a consequence of the contingent, temporal relationship between the behavior and drug reward. However, stimulant drugs also potentiate the rewarding effects of other reinforcers when administered noncontingently. OBJECTIVES: These studies were designed to determine whether noncontingent nicotine enhances the reinforcing properties of a nonpharmacological reinforcer and whether this direct effect facilitates operant behavior within the context of a nicotine self-administration procedure. METHODS:Rats self-administered nicotine or food, or received noncontingent nicotine, saline, or food either with or without a response-contingent, unconditioned reinforcing visual stimulus (VS). RESULTS: Noncontingent nicotine, whether delivered as discrete injections based on a pattern of self-administered nicotine or as a continuous infusion, increased response rates maintained by the VS. There were no significant differences in responding by animals that received contingent compared with noncontingent nicotine when a VS was available. This increase was not observed in the absence of the VS or as a consequence of noncontingent food delivery. Operant behavior was equally attenuated and reinstated by the removal and subsequent replacement of contingent and noncontingent nicotine. Nicotine supported self-administration in the absence of response-contingent, nicotine-paired stimuli; however, response rates were drastically reduced compared with nicotine self-administration with the VS. CONCLUSIONS:Nicotine influences operant behavior in two ways: by acting as a primary reinforcer when it is contingent upon behavior, and by directly potentiating the reinforcing properties of other stimuli through a nonassociative mechanism. Nicotine self-administration and smoking may be largely dependent upon this later action.
Authors: E C Donny; A R Caggiula; P P Rowell; M A Gharib; V Maldovan; S Booth; M M Mielke; A Hoffman; S McCallum Journal: Psychopharmacology (Berl) Date: 2000-09 Impact factor: 4.530
Authors: Matthew T Weaver; Maggie Sweitzer; Sarah Coddington; Jaimee Sheppard; Nicole Verdecchia; Anthony R Caggiula; Alan F Sved; Eric C Donny Journal: Nicotine Tob Res Date: 2012-01-04 Impact factor: 4.244
Authors: Matthew I Palmatier; Kimberley R Marks; Scott A Jones; Kyle S Freeman; Kevin M Wissman; A Brianna Sheppard Journal: Psychopharmacology (Berl) Date: 2012-10-23 Impact factor: 4.530
Authors: A D Lê; Steven Lo; Stephen Harding; Walter Juzytsch; Peter W Marinelli; Douglas Funk Journal: Psychopharmacology (Berl) Date: 2009-12-15 Impact factor: 4.530