BEHAVIORAL AND PHYSIOLOGICAL CONSEQUENCES OF A SINGLE SOCIAL DEFEAT IN ROMAN HIGH-AVOIDANCE AND LOW-AVOIDANCE RATS

The behavioural and physiological consequences of a single social defe at were studied in Roman high-avoidance (RHA) and Roman low-avoidance (RLA) rats, two rat lines with a genetically determined difference in the way of responding to or coping with stressors. Animals were subjec ted to social defeat by placing them in the cage of an aggressive male conspecific for 1 h. In both RHA and RLA rats, social defeat induced a profound increase in body temperature during the circadian resting p hase, lasting for up to 10 days after the conflict. The increase in re sting temperature was paralleled by a slight decrease in spontaneous h ome cage activity. Food intake and growth were suppressed for a number of days, resulting in a long-lasting lower body weight compared to no n-stressed control animals. An open field test 2 days after defeat sho wed a social stress-induced decrease in locomotion in a novel environm ent. Despite the well-known differentiation between RHA and RLA rats i n their behavioural and neuroendocrine response pattern to acute envir onmental challenges, the present study did not show major differences in the long-term consequences of social defeat. (C) 1997 Elsevier Scie nce Ltd.