1 Department of Psychology, Center for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Concordia University, 7141 Sherbrooke Street West, Room SP 244, Montreal, QC, H4B-1R6, Canada.
2 Department of Psychology, Center for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Concordia University, 7141 Sherbrooke Street West, Room SP 244, Montreal, QC, H4B-1R6, Canada. nadia.chaudhri@concordia.ca.

Nicotine-induced enhancement of Pavlovian alcohol-seeking behavior in rats.

Psychopharmacology (Berl). 2017 Feb;234(4):727-738

Authors: Maddux JN, Chaudhri N

Abstract

RATIONALE: Nicotine enhances responding elicited by Pavlovian cues that predict positive outcomes.

OBJECTIVES: We tested the hypothesis that nicotine acting at nicotinic acetylcholine receptors (nAChRs) would augment Pavlovian alcohol-seeking.

METHODS: Male, Long-Evans rats with unrestricted access to food and water were acclimated to drinking 15% ethanol in their home cages and then given Pavlovian conditioning sessions in which each trial of a 15-s conditioned stimulus (CS, 12 trials/session) was paired with 0.2 ml of ethanol (unconditioned stimulus, US, 2.4 ml/session). Entries into a port where ethanol was delivered were used to assess conditioning. Control groups received explicitly unpaired trials of the CS and US. In experiment 1, systemic injections of saline (1 ml/kg) or nicotine (0.4 mg/kg, freebase) were administered before each session. In experiments 2 and 3, an identical regimen of saline or nicotine injections was administered before the start of Pavlovian conditioning sessions.

RESULTS: All paired groups acquired conditioned port-entry responding to the CS, indicative of Pavlovian alcohol-seeking, whereas unpaired control group did not. Pre-session nicotine injections increased CS port-entries relative to saline, only in the paired group. This nicotine-induced enhancement of Pavlovian alcohol-seeking was blocked by pre-treatment with the nAChR antagonist mecamylamine. Prior exposure to nicotine did not influence the subsequent acquisition of Pavlovian alcohol-seeking.

CONCLUSIONS: These findings highlight for the first time that nicotine acting at nAChRs augments Pavlovian alcohol-seeking, specifically in non-restricted rats. Individuals who smoke and drink may thus be particularly susceptible to alcohol cues that could trigger further drinking.

PMID: 28011981 [PubMed - indexed for MEDLINE]