Hunger alters approach-avoidance behaviours differently in male and female mice

The decision about whether to approach or avoid a reward while under threat requires balancing competing demands. Sex-specific prioritisations (e.g. mating, maternal care), or generalised prioritisations (e.g. feeding, drinking, sleeping) may differently influence approach-avoidance behaviours based on the level of "risk" and homeostatic need state of the organism. However, given known sex differences in key aspects that may influence this behaviour, direct comparison of how male and female mice make decisions to approach or avoid a dangerous area while in a fasted state have yet to be conducted.

We conducted several approach-avoidance tasks with varied levels of risk and reward in male and female C57BL6J mice that were either fasted or sated (fed). Mice underwent a light-dark box, elevated plus maze, baited large open field and runway task to assess their approach and avoidance behaviour.

In the light-dark box and elevated plus maze, when no reward was available, fasted female mice showed greater approach behaviours than sated counterparts, while no difference was observed in males. In the baited large open field, when reward was available, both sexes showed increased approach behaviours when fasted. However, when sated, male mice conversely showed greater approach behaviours compared to sated female mice. In the runway task, while sated mice failed to learn, fasted male mice inhibited their reward consumption in response to increased shock intensity; however, fasted female mice were resistant to increased shock intensity.

Our study identifies sex differences in decision making behaviour in mice based on satiety state across several approach-avoidance tasks. We highlight several nuances of these differences based on reward availability and punishment intensity. These results shine a lens on fundamental differences between the sexes in innate, survival driven behaviours that should be considered for future studies.