Social reinforcement as alternative to sucrose reinforcement is increased by nicotine and methylphenidate in male Fischer-344 rats
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Stimulant drugs such as nicotine (NIC) and methylphenidate (MPH) are hypothesized to increase the reinforcing value of sensory stimuli, thus increasing the effectiveness of such reinforcers as alternatives to sucrose reinforcers.
Inbred Fischer-344 rats (n = 30) were assigned to three groups: saline (SAL; n = 10), nicotine (NIC; n = 10), or methylphenidate (MPH; n = 10). Testing was done in three phases: sucrose only, (SUC), sucrose and drug (SUC/DRUG), and sucrose, drug, and social reinforcement (SUC/DRUG/SOC). During the SUC phase, rats were trained on a progressive ratio 5 (PR5) reinforcement schedule for sucrose (20% solution). In the SUC/DRUG phase, animals were treated with SAL, NIC (0.4 mg/kg, n = 10 SC), or MPH (2.0 mg/kg, n = 10 IP) 30 min prior to testing. In the SUC/DRUG/SOC phase, animals continued receiving drug treatment, and social reinforcement was introduced concurrently with the sucrose reinforcer. The progressive ratio for each reinforcer ran independently of the others. Reinforcing value was measured as break point (BP), the highest number of responses resulting in a reinforcer.
SAL-treated animals showed no significant change in sucrose BP. MPH-treated animals showed decreased sucrose BP in the SUC/DRUG phase, with a further reduction in the SUC/DRUG/SOC phase. NIC-treated animals decreased sucrose BP only when a social alternative was offered.
Both NIC and MPH reduce the sucrose BP in the presence of a social alternative. The decrease in sucrose responding, coupled with increased social responding, suggests that the social alternative acted as an effective alternative reinforcer to sucrose. From a translational perspective, these results suggest that stimulant drugs such as NIC and MPH may increase the effectiveness of treatments that use alternative social reinforcers to decrease eating.
KeywordsBehavioral economics Operant Progressive ratio Social behavior
This work was supported by a grant from the center for translational research at the University of Buffalo and a grant from the National Institute of Drug Abuse (P50DA037844).
- Caggiula AR, Donny EC, White AR, Chaudhri N, Booth S, Gharib MA, … Sved AF (2002) Environmental stimuli promote the acquisition of nicotine self-administration in rats. Psychopharmacology 163(2), 230–237. https://doi.org/10.1007/s00213-002-1156-5
- Chaudhri N, Caggiula AR, Donny EC, Booth S, Gharib M, Craven L, … Sved AF (2006) Operant responding for conditioned and unconditioned reinforcers in rats is differentially enhanced by the primary reinforcing and reinforcement-enhancing effects of nicotine. Psychopharmacology 189(1), 27–36. https://doi.org/10.1007/s00213-006-0522-0
- Donny EC, Chaudhri N, Caggiula AR, Evans-Martin FF, Booth S, Gharib MA, … Sved AF (2003) Operant responding for a visual reinforcer in rats is enhanced by noncontingent nicotine: implications for nicotine self-administration and reinforcement. Psychopharmacology 169(1), 68–76. https://doi.org/10.1007/s00213-003-1473-3
- Lloyd DR, Medina DJ, Hawk LW, Fosco WD, Richards JB (2014b) Habituation of reinforcer effectiveness. Front Integr Neurosci 7. https://doi.org/10.3389/fnint.2013.00107
- Palmatier MI, Evans-Martin FF, Hoffman A, Caggiula AR, Chaudhri N, Donny EC et al (2006) Dissociating the primary reinforcing and reinforcement-enhancing effects of nicotine using a rat self-administration paradigm with concurrently available drug and environmental reinforcers. Psychopharmacology 184(3–4):391–400. https://doi.org/10.1007/s00213-005-0183-4 CrossRefPubMedGoogle Scholar