Vacuum-Based Vapor Exposure for Nicotine Studies

CVE was performed using a vacuum-based vapor exposure system from La Jolla Alcohol Research^{17 (link),19 (link),20 (link)}. Animals were placed into sealed home cages with their standard housing cage-mates for 8 hours a day, 5 days a week (9:00–17:00 M-F) before being returned to their standard home cages. The sealed cages continuously received clean room air from a down-stream vacuum pump (16 L/m), and a computer-controlled Electronic Nicotine Delivery System (ENDS) delivered vapor (3 sec, 200°C) at pre-defined inter-vape intervals (2, 5, 10, 15, and 60 minutes). The e-liquid vehicle (VEH) consisted of 50% propylene glycol (Sigma-Aldrich, P4347) and 50% vegetable glycerin (Sigma-Aldrich, G5516) (50/50 PGVG), and all experiments with nicotine (NIC) used a dose of 20 mg/ml (−)-nicotine (Sigma Aldrich, N3876). During all vapor exposure procedures, mice could move freely within the home cage with ad libitum access to food and water.