Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

Abstract

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.

Dynamic body weight and body composition changes in response to subordination stress

“…In rats, social defeat results in decreased body weight gain following acute social defeat as well as decreased food intake that persists for several days after the defeat session [22]. In studies using restraint stress, rats lose weight and remain hypophagic for several days after the stressor has ended [23].…”

Effect of social defeat in a territorial bird (Parus major) selected for different coping styles

“…These studies clearly showed that this paradigm provides a powerful and realistic methodology to study strategies to cope with naturalistic stress [9]. In rodents a social defeat affects the organism both at the physiological and behavioral level [9,11], with a general increase in sympathetic activity (heart rate and body temperature) lasting from one to several hours [12] and an impairment of social and explorative activity lasting up to several weeks [14]. Effects of social defeat have never been tested in birds although it is known that nestlings' activity and heart rate are very sensitive to an alarm call [18], which in many species is often emitted during fights.…”

“…Yet, most of the work is restricted to mammals, in particular rodents and primates, exposed to severe or chronic stress procedures (e.g., prolonged social isolation, housing in overcrowded environments or early maternal separation) very unlikely to occur in the real world. An attempt to modify this approach has been made by testing the effect of social defeat in territorial animals, mainly rodents [11,14,15,17,19]. These studies clearly showed that this paradigm provides a powerful and realistic methodology to study strategies to cope with naturalistic stress [9].…”

Acute Physical Stress Elevates Mouse Period1 mRNA Expression in Mouse Peripheral Tissues via a Glucocorticoid-responsive Element

“…uncontrollable stressors have been shown to induce changes in a wide variety of behavioral parameters, including decreases in general locomotor activity and explorative behavior as well as impairment of sexual behavior, feeding, and drinking (27). Social stressors can be uncontrollable.…”