Nicotine increases alcohol self-administration and reinstates alcohol seeking in rats.
OBJECTIVE
Alcohol and tobacco are often co-abused in humans and previous studies found that nicotine increases alcohol consumption in rats. Here, we studied whether nicotine would reinstate alcohol-taking behavior in drug-free rats and whether this effect would be enhanced by prior exposure to nicotine during alcohol self-administration training.


METHODS
Rats were trained to press a lever for alcohol (12% w/v, 1 h/day), and following stable alcohol intake groups of rats ( n=11-12) were given daily vehicle or nicotine (0.2, 0.4 or 0.8 mg/kg, SC) injections just prior to the self-administration sessions for 10 days. Rats were then given 6 days of alcohol self-administration in the absence of nicotine and an additional 5-10 drug-free days during which lever presses were not reinforced (extinction). Subsequently, rats were tested for reinstatement of alcohol seeking following exposure to priming injections of vehicle or nicotine (0.4 mg/kg, SC).


RESULTS
Nicotine increased alcohol self-administration in a dose- and time-dependent manner over the 10-day period. Nicotine also reinstated alcohol seeking after extinction of the alcohol-reinforced behavior, and this effect was strongly enhanced by prior nicotine exposure.


CONCLUSIONS
The present data extend previous studies on the effect of nicotine on alcohol self-administration, and further indicate that nicotine is an effective stimulus for reinstatement of alcohol seeking during drug-free periods.
Lê
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AD
Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada. anh_le@camh.net.|Department of Pharmacology, University of Toronto, Toronto, Canada. anh_le@camh.net.|Department of Psychiatry, University of Toronto, Toronto, Canada. anh_le@camh.net.
Wang
A
A
Department of Pharmacology, University of Toronto, Toronto, Canada.
Harding
S
S
Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada.
Juzytsch
W
W
Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada.
Shaham
Y
Y
Behavioral Neuroscience Branch, IRP/NIDA/NIH/DHHS, Baltimore, Md., USA.
D000428:Alcohol Drinking / Q000517:prevention & control* / Q000523:psychology; D000818:Animals; D016739:Behavior, Addictive / Q000139:chemically induced* / Q000517:prevention & control* / Q000523:psychology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage*; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D055502:Secondary Prevention; D012646:Self Administration
D000431:Ethanol; D009538:Nicotine