Specific features in the behavior of rats with different genetic stability to stress

Abstract

The effects of acute and chronic immobilization stress on the behavior of NISAG and outbred rats with different resistance to stress were evaluated. In the acute stress model, NISAG rats did not differ from stress-resistant outbred rats in the majority of the studied parameters. Chronic stress exhausted adaptive potential of NISAG rats, and their behavior became similar to that of rats with low resistance to stress.Key Words: emotional stress; behavior; resistance to stress There is evidence that the resistance to stress varies in animals of different and the same genetic strains [8]. The animals can be selected by this parameter [7]. At the same time it is important to understand physiological mechanisms responsible for formation of stress resistance in animals and humans. The use of experimental animals with different functioning of physiological systems determining stress resistance can be helpful in the investigation of these mechanisms.The purpose of the present study was to examine the effects of acute and chronic immobilization stress on the behavior of rats with different genetic resistance to stress. MATERIALS AND METHODSExperiments were performed on male outbred albino rats and on rats with genetically determined stressinduced arterial hypertension (NISAG). Stress was produced by a 2-h immobilization by fixing the legs (acute stress, AS) or 18-h restriction of mobility in an individual cage (chronic stress, CS). Before and after stress, motor and exploring activities were estimated in the open field test [6], the ability to Laboratory' of Psyehopharmaeology', Institute of Pharraacology of the Volgograd Medical Academy; "Laboratory of Experimental Pharmacology, Scientific and Research Cardiology Center, Ministry of Health, Moscow extrapolating avoidance [1] was evaluated, and the threshold electrostimulation pain (vocalization threshold) was determined. The rats were divided according to their resistance to stress as described previously [5] proceeding from parameters measured before acute and chronic stress.In the first series of experiments we studied behavioral dynamics under conditions of zoosocial (pair) interaction [2]. The test was carried under monochrome red light on isolated platform (area 1 m 2) with drinking bowl, feeding box, box with sawdust, and individual "shelter", which were located in the comers and were designed for one animal. Before the test the rats were deprived of food and water for 48 h. Individual and zoosocial behavior under competitive conditions was estimated visually by the main motor acts and postures. The data were pooled into 12 behavioral and emotion-motivation categories (vectors), on the basis of which the processes of the higher nervous activity were estimated in points by "a scale of judgements". The direction and intensity of changes were determined as the ratio between the mean value of each vector during the poststress period to its original value. RESULTSPreliminary tests revealed differences in the behavior of rats wkh different resistance to stress. Rats with

Motor and neurochemical correlates of aggressive behavior in male mice

“…A high general motor activity is typical of animals of those genetic lines that are characterized by a low level of fear in an unknown environment [19]. Submissive animals were usually described as manifesting a low, in general, motor activity [20,21], whereas in some studies such correlation was not found [22]. This is why we believed it expedient to check the presence or absence of correlation between the intensity of aggressive behavior and the level of locomotor activity in male mice.…”