Environmental stimuli promote the acquisition of nicotine self-administration in rats.
BACKGROUND
Environmental stimuli associated with drugs of abuse are believed to play a major role in the motivation to take drugs, drug dependence, and relapse. Previous work from this laboratory demonstrated that the response-contingent presentation of drug-related, visual cues was at least as important as nicotine in the maintenance, extinction and reacquisition of self-administration in experienced rats.


OBJECTIVE
In the present research, we asked whether these same visual cues are effective in promoting the acquisition of operant responding in drug naive rats.


METHODS
Male Sprague-Dawley rats were tested for self-administration of IV nicotine (0.03 mg/kg, free base) in 1-h daily sessions when infusions were or were not paired with two lighting events: a 1-s cue light, followed by a 1-min period during which the chamber light was turned off and responding was not reinforced.


RESULTS
Rats tested with cues plus nicotine rapidly acquired self-administration and increased their lever pressing rates as the schedule progressed from FR1 to FR5. Without cues, the rate of nicotine self-administration was low and no adjustments were made in response to increasing schedule demands. While one of the stimuli, turning off the chamber light, was shown to have primary reinforcing properties, its association with nicotine produced a synergistic enhancement of lever pressing. Acquisition of operant responding was also enhanced, but to a lesser extent, by a previously neutral compound stimulus, i.e. the nicotine-paired cue light presented with a 1-s tone.


CONCLUSIONS
These results illustrate a powerful interaction between environmental stimuli and nicotine in the acquisition of operant responding and indicate that both intrinsically reinforcing and previously neutral cues can participate in this effect.
Caggiula
Anthony R
AR
Department of Psychology, University of Pittsburgh, 3131 Sennott Square, Pittsburgh, PA 15260, USA. Tonypsy@pitt.edu
Donny
Eric C
EC
White
Anthony R
AR
Chaudhri
Nadia
N
Booth
Sheri
S
Gharib
Maysa A
MA
Hoffman
Alycia
A
Perkins
Kenneth A
KA
Sved
Alan F
AF
D000818:Animals; D016739:Behavior, Addictive / Q000523:psychology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D003463:Cues; D004780:Environment, Controlled; D008029:Lighting / Q000379:methods; D008297:Male; D009538:Nicotine / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012646:Self Administration / Q000523:psychology
D009538:Nicotine