In utero chemosensory experience alters taste preferences and corticosterone responsiveness

Litters of rat pups were exposed in utero (on Day 20 of gestation) to taste/odor stimulation by injection of an apple juice solution into the amniotic fluid. One group of control litters was exposed to a saline solution while a second control group received a sham-injection treatment. All litters were delivered by cesarean section and fostered to females that had given birth to a litter normally. Offspring were tested as adults in one of two two-bottle preference tests (apple solution vs tap water or maple solution vs tap water). Measures of total fluid consumption were converted to preference scores and plasma levels of corticosterone were determined. Analyses of these data indicated that offspring exposed to the apple solution in utero showed an increased preference for apple postnatally. No increased preference for maple solution was shown. In both preference tests the offspring exposed to apple or saline solutions via amniotic injection had reduced pituitary-adrenal activity compared to sham-injected controls. The results are compared to findings of other studies of pre- and postnatal stimulation on offspring behavior and pituitary-adrenal activity.