Reinforcer devaluation as a consequence of acute nicotine exposure and withdrawal.
BACKGROUND
Nicotine discontinuation produces behaviors in rats that are congruent with anhedonia, and these symptoms may be related to the devaluation of non-nicotine reinforcers.


OBJECTIVE
Four separate experiments were performed to explore the parameters surrounding nicotine-induced reinforcer devaluation.


METHODS
In Experiments 1 and 2, nicotine (0.1 or 0.3 mg/kg) or 0.3 mg/kg nicotine plus 1.0 mg/kg mecamylamine was delivered to rats prior to progressive ratio (PR) schedule sessions in which sucrose was used as a reinforcer. In order to evaluate (a) reinforcer enhancement by nicotine and (b) reinforcer devaluation in the absence of nicotine, all rats experienced two PR schedule sessions per day for 10 days. Experiment 3 involved nicotine (0.3 mg/kg) and a visual stimulus in place of sucrose reinforcement. In Experiment 4, rats received nicotine (0.3 mg/kg) either before or after a single PR schedule session for 10 days.


RESULTS
Experiments 1 and 2 demonstrate that reinforcer devaluation is related to the occupation of nicotinic-acetylcholine receptors. Results from Experiment 3 provide some evidence that devaluation occurs with either sucrose or visual-stimulus reinforcement. Experiment 4 demonstrates that a necessary condition for reinforcer devaluation to occur is the concurrent exposure to the reinforcer and nicotine.


CONCLUSIONS
Reinforcer devaluation in rats emerges rapidly in a progressive, orderly fashion that coincides with accumulated exposure to nicotine. These results suggest that reinforcer devaluation may be a feature of nicotine that contributes to the abuse liability of tobacco products.
Department of Psychology, Saint Michael's College, 1 Winooski Park Avenue, Colchester, VT, 05439-0001, USA, akirshenbaum@smcvt.edu.
Ari
A
Kirshenbaum
John
J
Green
Michael
M
Fay
Angelique
A
Parks
Jesse
J
Phillips
Jason
J
Stone
Tessa
T
Roy
D059445:Anhedonia / Q000187:drug effects*; D000818:Animals; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D009538:Nicotine / Q000009:adverse effects* / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000009:adverse effects* / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic; D012054:Reinforcement, Psychology; D013375:Substance Withdrawal Syndrome / Q000523:psychology*; D013395:Sucrose
D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; D013395:Sucrose; D008464:Mecamylamine; D009538:Nicotine