Oral self-administration of sweetened nicotine solutions by rats.

Oral self-administration of sweetened nicotine solutions in rats was studied in two ways. In the first experiment, one group had continuous access to a water bottle containing a sucrose solution and nicotine (10 micrograms/ml), while another group had access to an identical sucrose solution without nicotine. All rats had continuous access to water. While consumption of nicotine increased with increasing concentrations of sucrose, consumption of the sucrose+nicotine solution never exceeded the intake of sucrose alone. In subsequent experiments, the delivery of the solutions was made contingent upon an operant response. The sucrose+nicotine solution was found to maintain responding to higher response/reinforcer ratios than the sucrose only solution. These data demonstrate that rats will self-administer sweetened nicotine solutions and that sucrose+nicotine solutions are more reinforcing than sucrose solutions alone. Free access consumption is not a good predictor of the response maintaining properties of nicotine solutions.