EFFECTS OF POSTNATAL HANDLING OF RATS ON EMOTIONAL, HPA-AXIS, AND PROLACTIN REACTIVITY TO NOVELTY AND CONFLICT

The present studies evaluated whether or not postnatal handling (PH) ( administered during the first 21 days of life) could enduringly improv e coping behavior with novel and/or conflict situations. To this purpo se, different groups of naive male rats (control and PH-treated) were submitted in separate experiments to I of the 3 following situations: an emotional reactivity test (in 4-month-old animals), an open-field s ession followed by endocrine measurements (in 7-month-old animals) and a punished drinking test (in Ii-month-old animals). PH effects were s ignificant in the 3 situations: handled animals were less resistant to capture or to the handling maneuvers involved in the emotional reacti vity test; the hormonal responses (corticosterone, prolactin, and ACTH changes) during and after an open-held stress were less intense, and PH effects lasted up to 11 months in the punished drinking test, as me asured by a higher number of punished responses and less time spent fr eezing by handled animals during the punished period. The results are discussed in relation to previous evidence showing a long-lasting redu ction of fearfulness in rats due to postnatal handling. Copyright (C) 1996 Elsevier Science Inc.