The effect of taste familiarity on intake and taste reactivity in infant rats

Abstract

With infant rats, unlike with adults, increased intake of a taste after mere exposure to this stimulus is not consistently found; this has sometimes been interpreted as a failure by the immature subject to recognize tastes as familiar. We studied the effect of preexposure to a tastant, measuring taste reactivity and intake in 14-day-old rats. Familiarity increased hedonic response to sucrose, but also increased aversive response to quinine and ethanol. With the sucrose-quinine compound, familiarity increased both the hedonic and the aversive reaction to the stimulus. In no case was a differential reactivity to water observed. Significant increased intake after familiarization was only found with quinine or the sucrose-quinine compound. Results indicate that in infant rats, and with the present parameters, taste familiarity enhances responsiveness to these stimuli, an effect not always accompanied by detectable changes in intake.

Brief Exposure to Sensory Cues Elicits Stimulus-Nonspecific General Sensitization in an Insect

“…In other insects, brief exposure to sucrose elicited short-term sensitization as shown by PER responses in honey bees [40] and fruitflies [7]. In infant rats, pre-exposure to tastants (quinine, sucrose) has been shown to enhance responsiveness to these substances, discussed as a form of taste familiarity [41]. Interestingly, pre-exposure was repeated many times in this latter study, while a single pre-exposure was sufficient in ours.…”

The unconditioned stimulus pre‐exposure effect in preweanling rats in taste aversion learning: Role of the training context and injection cues

“…Saccharin solution was delivered at a constant rate (0.1 ml/min) by means of an infusion pump (KD Scientific, Holliston, MA) connected to each pup's oral cannula by a polyethylene catheter (Clay Adams, PE 50 Parsippany, NJ). With these infusion parameters, pups are capable of either consuming or rejecting the infused solution (Arias, et al, 2010; Diaz-Cenzano & Chotro, 2010). After the infusion procedure, subjects were weighed to estimate saccharin consumption scores by means of the following formula: [(Post-infusion body weight − Pre-infusion body weight)/ Pre-infusion body weight] × 100.…”

MC4-R signaling within the nucleus accumbens shell, but not the lateral hypothalamus, modulates ethanol palatability in rats

“…The TR procedure has been successfully employed to characterize taste palatability of an ample range of tastant stimuli [8, 10, 15], including ethanol solutions [10, 16]. In this regard, it is important to note that our saline-treated rats showed a similar pattern of complex hedonic ingestive and aversive reactions to ethanol that have previously been reported when ethanol is administered and is not a novel stimulus [13, 17].…”

“…To do that, stereotyped mouth, tongue, and body movements are employed as indicators of the animal’s perceived palatability of the substance [9]. Ingestive responses are associated with fluid consumption and positive hedonic reactions, while aversive responses promotes the expulsion of fluid from the oral cavity and are valid indexes of negative hedonic reactions to the fluid being evaluated [8,10]. …”

“…The video files were scored, in real time and frame by frame, by two raters blind to the treatment conditions (inter-rater correlations: rs 0.96). Based on previous studies [10, 13], the typical reactions to ethanol flavor were considered and categorized as either hedonically ingestive or aversive. The category of ingestive hedonic reactions included “mouthing”, “tongue protrusions” and “paw licking”.…”