Abstract

Specific pairs of drugs such as cocaine and ethanol and nicotine and ethanol are widely used by humans. A variety of existing studies have reported behavioral and pharmacological interactive effects between these pairs of drugs. The present thesis was designed to further examine the potential interactive effects between these pairs of drugs as reflected in two variants of the Conditioned Taste Aversion (CTA) paradigm. Experiment 1 examined the potential for cocaine and ethanol to interact pharmacologically in the pretreatment CTA procedure. These results revealed that while cocaine and ethanol may interact pharmacologically, their interaction was asymmetrical and therefore not cocaethylene mediated. Experiment 2 examined the potential for nicotine and ethanol to interact pharmacologically in the pretreatment CTA procedure. These results demonstrated that nicotine and ethanol interacted pharmacologically in an asymmetrical fashion. Together, these pretreatment effects indicated a pharmacological specificity between pairs of drugs as reflected in their interaction. Experiments 3 and 4 were conducted in order to assess whether cocaine and ethanol as well as nicotine and ethanol were functionally related and endowed with overlapping stimulus properties as reflected in the pre-exposure CTA paradigm. These results demonstrated that both pairs of drugs were functionally related and endowed with overlapping but non-identical stimulus properties. That is, cocaine less effectively disrupted CTA to ethanol while ethanol more effectively disrupted CTA to cocaine. Similarly, nicotine effectively disrupted CTA to ethanol while ethanol less effectively disrupted CTA to nicotine. Taken together, these asymmetrical pre-exposure effects were thought to be related to the self-administration potential of these drugs.