Schedule-induction of nicotine self-administration.

Nicotine, although assumed to be an important factor in maintaining the use of tobacco products, has produced equivocal results when tested in drug self-administration studies using standard procedures with laboratory animals. Several recent studies however, have demonstrated nicotine self-administration using a procedure of schedule-induction. Schedule-induced behaviors occur as an adjunct to behavior controlled by an intermittent schedule of reinforcement and are thus not under control of the scheduled contingencies. Using schedule-induction procedures; oral, intravenous and inhaled self-administration of nicotine has been shown in rats, both rats and rhesus monkeys, and humans respectively. Although the self-administration of some doses of nicotine occurred without a concurrent schedule of intermittent reinforcement, schedule-induction results in responding maintained by lower doses of the drug and much more rapid initiation of self-administration. The result of such studies suggest an interaction between environmental factors, such as an intermittent schedule of other reinforcers, and nicotine's pharmacological effects. This interaction may be important in understanding the etiology and maintenance of human tobacco use.