Lorazepam treatment in the neonatal rat alters submissive behavior in adulthood

Male hooded Lister rats were cross-fostered at birth (day 0) and reared in litters of eight. Within each litter, one pup was treated with each dose of lorazepam (0.25 or 1.25 mg/kg) and one was treated with the placebo vehicle. The pups received daily subcutaneous injections between postnatal days 7 and 21 inclusive. Starting on day 70 the animals were subjected to four tests of exploratory and social behavior: Open Field, Holeboard, Social Interaction and Home-Cage Aggression. The drug-treated animals showed an increase in submissive behavior, particularly when intruding into another animal's territory, but only minimal changes in their performance in the other three tests.