Drug doses were based on previous reports [14] (link). Upon stable baseline behavior, drugs were administered in the following order: the nicotinic acetylcholine receptor (nAChR) agonist Nicotine (0, 0.1, 0.3, 1.0 mg/kg), the nAChR antagonist mecamylamine (0, 0.5, 1.0, 2.0 mg/kg), the muscarinic acetylcholine (mAChR) antagonist scopolamine (0, 0.03, 0.1, 0.3 mg/kg), and the mAChR agonist oxotremorine (0, 0.01, 0.03, 0.1 mg/kg). Nicotine and mecamylamine were purchased from Sigma-Aldrich Canada (Oakville, ON, Canada), whereas scopolamine and oxotremorine were purchased from Tocris (Minneapolis, MN, USA). All drugs were dissolved in 0.9% sterile saline and administered in a volume of 1 ml/kg via intraperitoneal injection.
All drugs were prepared fresh daily, and administration adhered to a digram-balanced Latin Square design (for doses A–D: ABCD, BDAC, CABD, DCBA, as per p.329 of [23] ). The three-day injection schedule started with a baseline session, followed by a drug or saline injection session, and then by a non-testing day. Injections for Nicotine and mecamylamine were administered 10 min before behavioral testing; scopolamine injections were administered immediately before testing; and oxotremorine injections were administered 15 min before testing. Animals were given a minimum of one week drug-free testing between compounds to minimize any carryover effects.
All drugs were prepared fresh daily, and administration adhered to a digram-balanced Latin Square design (for doses A–D: ABCD, BDAC, CABD, DCBA, as per p.329 of [23] ). The three-day injection schedule started with a baseline session, followed by a drug or saline injection session, and then by a non-testing day. Injections for Nicotine and mecamylamine were administered 10 min before behavioral testing; scopolamine injections were administered immediately before testing; and oxotremorine injections were administered 15 min before testing. Animals were given a minimum of one week drug-free testing between compounds to minimize any carryover effects.