Varenicline

Varenicline was provided by the manufacturer Pfizer. The dosing was as per product labelling.

Ethanol (95% v v⁻¹; Gold Shield Chemical Co., Hayward, CA, USA) was diluted with dH₂O to 20% solutions. Varenicline (6,7,8,9-tetrahydro-6,10-methanol-6H pyrazino[2,3-h][3]benzazepine tartrate) was generously provided by Pfizer Global Research and Development (Groton, CT, USA). For systemic injections, Varenicline (1.0 mg kg⁻¹, s.c.) dissolved in saline (0.9%) or vehicle (saline, s.c.) was administered in a volume of 1 mL kg⁻¹, and ethanol (20%, 2.5 g kg⁻¹, i.p.) or vehicle (dH₂O, i.p.) was administered during in vivo microdialysis. For microinfusion experiments, Varenicline (0.5, 1 and 2 µg) was dissolved in 10% potassium phosphate buffer/90% isotonic saline solution, and thereafter, the pH was adjusted to 7.4 with NaOH (1 N). Vehicle infusions consisted of 10% potassium phosphate buffer/90% isotonic saline. The broad-spectrum β2* nAChR-antagonist dihydro-β-erythroidine (DHβE, 100 nM) and the α6* nAChR-selective antagonist α-conotoxin MII [α-CTXMII at 30 nM concentrations has no effect at non-α6/α3 nAChRs (Cartier et al., 1996 (link))] were purchased from Tocris Bioscience (Bristol, UK) and dissolved in saline. Drug and molecular target nomenclature accords with the British Journal of Pharmacology's Concise Guide to Pharmacology (Alexander et al., 2013a (link)).