Nicotine hydrogen tartrate salt

Mecamylamine hydrochloride (Tocris Bioscence) was diluted in 0.9% sterile saline and injected subcutaneously at a dose of 2 mg/kg. (-)-Nicotine hydrogen tartrate salt (MP Biomedicals) was dissolved in 0.9% sterile saline (pH 7.4), and doses of nicotine refer to the free-base form. Ketamine (KetaVed, Patterson Veterinary) and xylazine (AnaSed, Patterson Veterinary) were diluted in sterile saline and simultaneously injected intraperitoneally at a dose of 100 and 10 mg/kg, respectively, for mouse perfusions. Isoflurane (IsoFlo, Abbott Laboratories) was administered as a 1–3% mixture with oxygen via inhalation.

The cannabinoid receptor agonist WIN55,212–2 mesylate (Tocris/Bio-Techne Corp, Minneapolis, ME, USA) was dissolved in vehicle containing 1% DMSO, 1% Tween-80, and 98% saline (sterile 0.9% NaCl). The doses of WIN55,212–2 administered were 2 or 0.2 mg/kg intraperitoneally (i.p.). The moderate dose of WIN (2 mg/kg) was selected based on prior studies demonstrating altered neural function with adolescent exposure in mice and rats [26 (link), 27 (link)], and the low dose of WIN (0.2 mg/kg) was selected since this amount of drug has been shown to sustain daily reinforcing self-administration behavior in adolescent rats (~16 infusions/day at 0.0125 mg/kg/infusion = ~0.2 mg/kg per day) [28 (link)]. (-)-Nicotine hydrogen tartrate salt (MP Biomedicals, Santa Ana, CA, USA; 0215355491) was dissolved in 0.9% sterile saline and adjusted to pH 7.4. Nicotine was administered at a dose of 0.36 mg/kg, subcutaneous (s.c.) (free-base form); this dose is considered to be within the rewarding range of the dose response function that also elicits a behavioral response in adolescent C57BL/6J mice [29 (link), 30 (link)]. Peripheral injections were administered at a volume of 10 mL/kg.