Postnatal handling reduces emotionality ratings and accelerates two-way active avoidance in female rats

The present study evaluated whether postnatal handling (PH; administered daily during the first 21 days of life) could reduce anxiety or emotional reactivity in tasks of either spontaneous or conditioned fear-related behavior. To this purpose control nonhandled and postnatally handled female rats were submitted to three different behavioral tests: an emotionality rating (ER) followed by an elevated plus-maze test of anxiety in one experiment, and an acquisition of two-way active (shuttlebox) avoidance under two different training conditions in a separate experiment. Significant effects of PH treatment appeared in the three testing situations, clearly indicating an important and enduring reduction of emotionality/anxiety in PH-treated rats. Of special interest were the results of shuttlebox training: by shortening the conditioned stimulus (CS) and the intertrial interval (ITI) duration, avoidance acquisition was impaired as expected but the improving effects of PH were even more marked. The results are discussed in relation to previous studies reporting controversial results in the same (or similar) testing situations.