CONDITIONS SUFFICIENT FOR THE PRODUCTION OF ORAL COCAINE OR LIDOCAINESELF-ADMINISTRATION IN PREFERENCE TO WATER

Groups of rats were given a chronic history of drinking cocaine soluti ons of different concentrations in daily, 3-h schedule-induced polydip sia sessions. Animals failed to develop a preference for cocaine solut ion to concurrently presented water. Schedule-induction conditions wer e maintained, and the animals were divided into separate groups, drink ing either cocaine or lidocaine placed in a highly acceptable vehicle (glucose-saccharin solution). Animals preferred their respective drug solutions to concurrently presented water, and these preferences remai ned stable after the glucose-saccharin vehicle was gradually faded to water, leaving only cocaine or lidocaine, respectively, in the solutio n. Thus a stable preference for drug solution to water could be instit uted in rats for either cocaine or lidocaine solution (putative reinfo rcing and nonreinforcing agents, respectively) given an appropriate as sociative history, with high intakes maintained by schedule-induction. Conditions sufficient for the initiation of an oral preference and hi gh intake for a putatively reinforcing drug cannot be assumed to occur owing to the drug's reinforcing property in the absence of demonstrat ing the ineffectiveness of an appropriate negative control substance.