Flavor preexposures in a conditioned taste aversion situation: a dissociation of behavioral and endocrine effects in rats.
A series of experiments examined the effects of flavor preexposures on pituitary-adrenal/behavior relations in a conditioned taste aversion paradigm. It was found that reexposure to a novel milk solution paired earlier with lithium chloride (LiCl) elicited conditioned activation of the pituitary-adrenal system (Experiment 1). The unconditioned response to LiCl (measured by changes in plasma levels of corticosterone) did not vary as a function of prior (2 and 5 vs. 10) exposures to the milk solution (Experiment 2). Increased familiarity with the substance (resulting from 10 prior exposures) rendered the conditioning of a taste aversion to this substance less effective. Further, reexposure to this familiar substance after its pairing with LiCl was not accompanied by the characteristic conditioned pituitary-adrenal activation (Experiment 3). By titrating the number of conditioned stimulus (CS) preexposures (Experiment 4) it was found that within the range of preexposures manipulated (5-10), subjects exhibited (a) a coupling of behavioral and pituitary-adrenocortical responses when the conditioned taste aversion to the milk solution was paralleled by elevated plasma corticosterone (5-6 preexposures), (b) a coupling of these two response systems when flavor consumption was accompanied by suppressed plasma titers of corticoids (9-10 preexposures), or (c) a dissociation of the two system when the conditioned taste aversion was not accompanied by conditioned adrenocortical activity (7-8 preexposures). These data are discussed in terms of a dissociation in the effects of CS preexposures on conditioned adrenocortical and behavioral response systems.
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003345:Corticosterone / Q000097:blood*; D004326:Drinking / Q000187:drug effects; D008094:Lithium / Q000633:toxicity; D008297:Male; D010913:Pituitary-Adrenal System / Q000502:physiology; D051381:Rats; D013649:Taste / Q000502:physiology*
D000324:Adrenocorticotropic Hormone; D008094:Lithium; D003345:Corticosterone