Postnatal handling reduces anxiety as measured by emotionality rating and hyponeophagia tests in female rats.

The present studies evaluated the short- and long-lasting effects of postnatal handling (administered during the first 21 days of life) on the emotional behavior of female Sprague-Dawley rats. The performance of postnatally handled (H) and control nonhandled (NH) animals was compared in two different situations: an emotionality rating (ER) test (when they were 40 days or 4 months old), and a hyponeophagia (neophobia) test of anxiety, at the age of 4 months. The results showed that postnatal handling induced both short-term and long-term reductions of spontaneous emotional reactivity in the ER test, although the effects on some measures disappeared in 4-month-old rats. Postnatal handling also induced enduring decreases of anxiety as measured by the hyponeophagia test. None of the observed effects were attributable to changes in basal locomotor activity. ER measures were significantly related to hyponeophagia, because animals showing the highest emotionality scores in the ER test (preferentially NH animals) were those that showed the highest eating latencies and spent less time eating in the neophobic situation (i.e., hyponeophagia test).