Infant @entity35 exhibit aversive learning mediated by @entity1068 's orosensory effects but are positively reinforced by XXXX 's post-ingestive effects.

@entity167 @entity1068 @entity35
Previous work suggest aversive and appetitive hedonic effects of intraorally delivered @entity167 in pre-weanling @entity35 . Pups are reluctant to perform an operant response when reinforced with intraoral @entity167 infusions, a result suggesting aversive orosensory properties of @entity167 . Yet, post-absorptive effects of @entity1068 seem capable of supporting appetitive conditioning. Two experiments were conducted to test this phenomenon. Both included a pre-exposure phase (postnatal day 13, PD13) comprising intraoral stimulation with water or @entity167 . In Experiment 1, pups were given pairings between a tactile conditioned stimulus (CS) and intraoral infusions of @entity167 or water. A subsequent tactile preference test revealed that pups spent significantly less on the @entity167 -related CS relative to time spent on the alternative CS. In Experiment 2 pups were exposed to a texture CS (sandpaper) while intraorally infused with @entity167 or during a later @entity167 post-infusion interval. A tactile locational test conducted on PD16 indicated that @entity167 -pre-exposed animals that experienced sandpaper paired with @entity167 's post-absorptive effects exhibited a significant preference for the CS, even relative to a control group that experienced non-reinforced exposure to the tactile CS during conditioning. These results confirm that intraoral @entity1068 acts as an aversive tastant. A brief pre-exposure to @entity167 allows later expression of appetitive learning mediated by the drug's post-ingestive effects.
