Comparison of the effects of infant handling, isolation, and nonhandling on acoustic startle, prepulse inhibition, locomotion, and HPA activity in the adult rat

This study examined whether early isolation (EI), early handling (EH), or e arly nonhandling (NH) in infant rats alters (a) prepulse inhibition (PPI) o f the acoustic startle response (ASR) or its disruption by apomorphine. (b) motor activity or its stimulation by amphetamine, or (c) corticosterone ac tivity (because of its modulation of dopamine activity), in adulthood and i n comparison with a normal-husbandry postnatal control environment. EI did not affect PPI, reduced PPI disruption by apomorphine in males, and increas ed amphetamine-stimulated activity in males. NH increased the ASR, reduced activity in the open field, and increased corticosterone reactivity in male s. In all paradigms, the effects of EH were similar to those of the control environment. This study provides an important contribution to the evidence on the relationship between postnatal experience and long-term neurobehavi oral development in the rat and the relevance of this approach to animal mo dels of neuropsychiatric disorder.