Nicotine and schedule-induced drinking in rats

In the first experiment 4 rats developed schedule-induced water drinking during daily 1 hr sessions of a fixed-time 1 min schedule of food pellet delivery. Injections of a range of doses (0.25, 0.5, 1.0, 2.0 and 4.0 mg/kg) of nicotine hydrogen tartrate were found to produce a dose related attenuation of water intake. The higher doses also reduced the numbers of entries into the food tray in three rats, while the lowest dose consistently facilitated this behavior in the same animals. In a second experiment schedule-induced water drinking developed in 4 other rats under a similar schedule. Substitution of nicotine solution (0.05 and 0.1 mg/ml) for the water reduced volumes of fluid consumed. However, schedule-induced drinking continued at a rate sufficient for the animals to ing-st average doses of the nicotine salt of up to 8.5 mg/kg. It is concluded that schedule-induced drinking can be used successfully as a method of inducing self-administration of nicotine by rats.