Sex-dependent modulation of flavour neophobia by acute forced swim stress in rats

Flavour neophobia (the reduced intake of unfamiliar flavours) is a common response across species, including humans. Although several variables such as developmental stage, prior flavour experience or context are known to influence neophobia, the impact of acute stress remains largely underexplored. In this study we examined whether a brief stress exposure alters neophobic behaviour. Adult male and female Wistar rats were subjected to acute stress using the forced swim test, while controls were handled but not stressed. Immediately afterward, we recorded two locomotor measures that are typically sensitive to changes in arousal and emotional changes (distance travelled and number of rearings) to verify the effects of the stress manipulation. Neophobia was then assessed in the home cage by offering access to a 0.04% saccharin solution. As expected, females showed stronger neophobia than males. Stress increased neophobia only in males, whereas locomotor activity revealed the opposite pattern: females were more active overall and showed a stress-related reduction in both activity measures. These results point to sex-dependent differences in how acute stress influences behavioural responses to novel foods and suggest that stress-related changes in arousal may contribute to these effects.