Nicotine tartrate

d-Amphetamine sulfate salt at 0.1 and 0.3 mg/mL (Sigma-Aldrich; St. Louis, MO) and (−)-nicotine tartrate at 0.4 mg/mL (MP Biomedicals; Irvine, CA) were dissolved in 0.9% saline and injected at a volume of 1 mL of solution/kg of body weight. d-Amphetamine was injected intraperitoneally (IP) using a 15-minute injection-to-placement interval (IPI) and nicotine was injected subcutaneously (SC) using a 5-minute IPI. The IPI is defined as the length of time between the injection and the start of the session. Rats were returned to the home cage after each injection. Before the session, rats were transported to the experimental room in a transport cart and placed in the conditioning chamber within 1-minute of the session starting. Nicotine was brought to a pH of 7.0 ± 0.2 with a dilute NaOH solution. d-Amphetamine doses are reported in salt form while nicotine doses are in base form — per field standards. All doses, IPIs, and routes of administration were based on published research (Huynh et al., 2020; Palmatier et al., 2005 (link); Slezak et al., 2018 (link)).

d-Amphetamine sulfate at 0.1, 0.3, 0.6, and 1.0 mg/mL (Sigma-Aldrich; St. Louis, MO) was dissolved in 0.9% saline and injected intraperitoneally using a 15-minute injection-to-placement interval. The injection-to-placement interval was considered the time from injection to the start of the experimental session. d-Amphetamine (AMP) doses are reported in salt form. (−)-Nicotine tartrate at 0.03, 0.06, 0.1, and 0.3 mg/mL (MP Biomedicals; Irvine, CA) was dissolved in 0.9% saline and injected subcutaneously using a 5-minute injection-to-placement interval. Nicotine (NIC) doses are reported in base form per field standards. NIC solution was brought to a pH of 7.0 ± 0.2 using a dilute NaOH solution. In all cases, injections were given at 1 mL of solution/kg of body weight from the home cage. Before the session, and after their last injection, rats were moved the short distance to the experimental room using a transport cart. Doses, injection-to-placement intervals, and routes of administration were based on published research (Barrett et al., 2020 (link); Huynh et al., 2020 (link); Slezak et al., 2018 (link)).

(−)-Nicotine tartrate (MP Biomedical, Solon, OH) was dissolved in isotonic saline, and the pH was adjusted to 7 with NaOH solution. Mecamylamine hydrochloride (Sigma Aldrich, St. Louis, MO) was dissolved in isotonic saline. All injections were given subcutaneously (s.c.) into the flank at a volume of 1 ml/kg. All doses are expressed as those of the base.

(−)-Nicotine tartrate (MP Biomedical, Solon, OH) was dissolved in isotonic saline, and the pH was adjusted to 7 with NaOH solution. Galantamine hydrobromide (TCI America, Portland, OR) was dissolved in isotonic saline. All doses are expressed as those of the base. Injections were given s.c. into the flank at a volume of 1 ml/kg.

Nicotine tartrate (MP Biomedicals, Solon, OH, USA) was dissolved in 0.9% sterile saline and the pH was adjusted to 7.2. Ketamine (Ketavet, St. Joseph, MO), xylazine (Akorn; Lake Forest, IL), cefazolin, meloxicam, and heparin (all from Henry Schein, Melville, NY) were administered at doses listed previously.