Proceedings of the 9th International Multidisciplinary Conference «Stress and Behavior» Saint-Petersburg, Russia, 16–19 May 2005.Increasing pressure of environmental stressful stimuli worldwide, such as fear of terror attacks and dramatic climate catastrophes raises the level of stress in the society, thus, resulting in a higher risk of psychosomatic disorders and a lower quality of life. This requires further improvement of stress medicine and, particularly, development of adequate animal models that would reflect individual differences in vulnerability to stress during extreme environmental danger. Here we propose a paradigm of acute predator stress in mice as a model of extreme environmental stress in humans. In this study, we related individual differences of animal’s stress-responsiveness in this model to parameters of behavioral coping in other paradigms. First, male CD1 mice were tested in the forced swim test, resident-intruder paradigm and sucrose test. Several weeks later, they were exposed to a predator stress for a time period of 9 h. Then they were placed into a small container and introduced into a cage, which contained a rat; mice were water- and food-deprived during the entire period of stress. A subgroup of mice received an i.p. injection of antidepressant imipramine (30 mg/kg) 30 min prior to stress. Non-stressed animals remained untreated and were kept in regular animal facility. Immediately after the stress period, stressed and non-stressed animals were tested for their vertical activity and preference to sucrose. Stressed mice exhibited an increased preference to sucrose and total consumption of liquids as compared to control, while their locomotor activity remained unaltered. Administration of imipramine before stress prevented stress-induced changes in sucrose preference. The mice that demonstrated subdominant copying in the resident-intruder test, demonstrated significantly higher values of consumed liquid as compared to dominant individuals, while in baseline conditions parameters of sucrose test did not differ between subgroups. Dominant mice demonstrated a larger variability in preference to sucrose measured after stress than their subdominant counterparts. Dominant animals had higher scores of vertical activity in the novel cage test in comparison to subdominant mice. In subdominant individuals, vertical activity correlated with preference to sucrose that was not a case for dominant animals. In dominant mice, the increase in preference to sucrose negatively correlated with latency of attack. Parameters of floating behavior in the forced swim did not correlate with any of variables measured before nor after stress. Our experimental approach possibly may be useful in modeling of individual features of human behavior and stress-responsiveness in extreme situations
