Control by food deprivation cues interferes with the ability to learn drug state cues in male and female Sprague-Dawley rats.

Although interoceptive stimuli arising from food deprivation or drug states have been recognized as important internal regulators of behavior, e.g., eating and drug use, respectively, little is known if a history with one set of cues, e.g., food deprivation, would impact learning with another, e.g., drug states. The present study investigated whether interoceptive learning involving food deprivation influences the acquisition of an interoceptive drug-state discrimination. In Experiment 1, male and female Sprague-Dawley rats were trained to discriminate deprivation states (24+/0- or 0+/24-) signaling food reward. A subset of animals under the 24+/0- condition learned the discrimination, whereas a subset of animals under the 0+/24- condition did not. In Experiment 2, animals from these two subsets were trained on a discrimination in which morphine signaled a pairing of a saccharin solution with the emetic LiCl, and the morphine vehicle signaled saccharin alone. All animals learned this discrimination (avoiding saccharin when it was preceded by morphine and consuming it when it was preceded by the drug vehicle). Animals that failed to learn the initial food deprivation discrimination (Group 0+/24-) learned the morphine discrimination faster and to a greater level than animals that learned the earlier food deprivation discrimination (Group 24+/0-). These results suggest that learning about specific state cues may interfere with subsequent state learning by shifts in attention to specific state cues, the specific associations with these cues, and/or the similarity between the specific state cues assessed. This interference highlights the complexity of interoceptive cues and their implications for understanding dysregulated intake.