Sensitive period for the acceptance of unpalatable flavors in the presence of a preexposed odor in infant rats

Abstract

It has been shown that exposure to familiar odors facilitate the acceptance of bitter flavors in preweanling rats, yet it unknown how long this phenomenon persists. This study assessed, in 9- or 15-day-old Wistar rats, the influence of a familiar scent (i.e., lemon) on the intake of and behavioral responsiveness (i.e., mouthing, paw lick, chin rub, head shake, among other taste reactivity responses) elicited by a 0.1% quinine solution. The results showed heightened quinine intake in 9-day-old rats that had been preexposed to the odor, when compared to non-preexposed controls. This result was replicated in Experiment 2, which also documented no alterations in behavioral responsiveness toward quinine in the 9-day-old rats, as a function of the pre-exposure. More importantly, 15-day-old rats exhibited no alterations in intake or behavioral responsiveness toward quinine as a function of odor pre-exposure. These results suggest that the effects of odor pre-exposure upon acceptance of bitter tastes may occur within a sensitive period for the acceptance of bitter food.