Post-weaning handling attenuates isolation-rearing induced disruptions of prepulse inhibition in rats

Isolation rearing is a developmentally specific non-pharmacological manipul ation in rats that produces a deficit in sensorimotor gating, as measured b y prepulse inhibition (PPI) of the startle reflex. Previous research has de monstrated that the isolation rearing effect on PPI is sensitive to several factors, including the time of testing with respect to length of isolation . prepulse intensities used, strain of rats, and type of housing environmen t. This study tested whether handling is another factor that interacts with the isolation-rearing paradigm in PPI. Rats were housed either in the soci al (three rats per cage) or isolate (one rat per cage) conditions and were handled either 1-2 times per week (minimal handling) or on a daily basis (d aily handling). All rats were then tested at 8 and 10 weeks post-weaning. T here was an interaction between housing and handling, In the minimal handli ng condition, isolation rearing produced a deficit in PPI. This effect was absent, however, in the daily handling condition. Thus, regular handling of rats may interfere with the observation of the isolation rearing effect on PPI and should be carefully controlled in studies using this animal model of PPI deficits. (C) 2001 Elsevier Science B.V. All rights reserved.