MALE CF-1 MICE WERE ISOLATED OR GROUP HOUSED FROM WEANING UNTIL 45 DAYS OF AGE. AT 45 DAYS OF AGE, ISOLATED SS SHOWED HIGHER LEVELS OF LOCOMOTOR ACTIVITY ELEVATED BRAIN-SEROTONIN LEVELS, AND AN INCREASED RATE OF BRAIN-SEROTONIN TURNOVER, WITH A LOWER BRAIN-SEROTONIN TURNOVER TIME. DIFFERENCES SUGGEST THAT THE BEHAVIORAL PATTERN, WHICH DEVELOPS IN MICE AS A RESULT OF HOUSING UNDER ISOLATED CONDITIONS, MAY BE RELATED TO THE ALTERED PATTERN OF BRAIN-SEROTONIN METABOLISM WHICH EMERGES WITH ISOLATION. (PsycINFO Database Record (c) 2006 APA, all rights reserved)