Abstract
Estradiol plays a role in female sex-specific behaviors. The normal estrous cycle provides a natural within-subject experiment with which to test this role: estradiol fluctuations across the estrous cycle impacts many behaviors, including consumption. While it is anecdotally thought that this latter effect reflects an impact of estrous cycle phase on the palatability of tastes, this interpretation has never been directly tested. Here, we do so, using a behavioral assay known as the Brief Access Task (BAT) which enables the almost real-time quantification of preferences for large batteries of tastes ranging in palatability. Female rats were exposed to water, sucrose, saccharine, sodium chloride, citric acid, and quinine hydrochloride multiple times across the ~5 days of their estrous cycles, while we simultaneously tracked their cycle phases through vaginal smears and cytology. Overall consumption proved stable across the estrous cycle, but both consumption and bout size (a reliable measure of palatability) analysis revealed fluctuations in palatability: specifically, we observed an increase in preferences for palatable and a decrease in preferences for aversive tastants during Metestrus [F(1,4) = 4.61, p=0.001]—the phase of the estrous cycle during which estradiol levels are consistently higher than those of other relevant hormones. This suggests that hormonal fluctuations across the estrous cycle impact palatability of tastes in female rats.