The Non-Discrimination Between Nicotine and Cigarette Smoke Extract in Male and Female Rats
Although nicotine is the primary focus in tobacco research, the other ~7000 constituents in cigarette smoke are thought to interact with nicotine to contribute to the pharmacological effects relevant to tobacco use disorder. Using a Pavlovian drug discrimination task, we hypothesized that rats would discriminate between nicotine-alone and in cigarette smoke extract (CSE) based on the presence of constituent chemicals. Behaviour is assessed using three types of occasion setting training: nicotine as a positive feature (FP) discriminating from vehicle, FP CSE versus vehicle, and FP CSE versus nicotine as a negative feature. This final group determines whether rats can discriminate based on constituents. Subjects readily discriminate between nicotine and vehicle and between CSE and vehicle; however, they are unable to discriminate between CSE and nicotine after 576 pairings. Interestingly, we demonstrate that CSE and nicotine do not create distinct interoceptive environments under current training conditions to appropriately guide approach behaviour.