Further evidences that risk assessment and object exploration behaviours are useful to evaluate emotional reactivity in rodents.

In this study, we tested the ability of risk assessment and exploration behaviours to emphasise PH effects. Indeed, postnatal handling (PH) decreases emotional reactivity in rats but inconsistent behavioural results can be observed and may be due to false negative (i.e. existing effects are not detected). Risk assessment behaviours were measured in the elevated plus maze, in the free exploration paradigm and in the open field. In addition, we measured object exploration behaviours towards familiar/new objects in the open field. PH increased general activity in the elevated plus maze and in the free exploration paradigm and risk assessment behaviours allowed demonstrating that these effects were specific to emotional reactivity. In the open field, PH increased object exploration as early as first exposition while general activity was unaffected. PH also decreased behavioural inhibition in response to the introduction of a novel object. On the whole, our results show that risk assessment and object exploration behaviours are valuable tools to measure more precisely emotional reactivity in rodents. This reinforces the idea that these behaviours should be used more frequently in order to avoid false negative when emotional reactivity changes are expected in unconditioned conflict tests.