[The experimental model of establishment and maintenance of social hierarchy in laboratory mice]

The goal of the investigation is to establish a new experimental model of social hierarchy in laboratory mice. The important feature of the model is a group of two males only placed into the special experimental cage. The cage consists of two nestling chambers and central chamber. Observations were made 3 times per day (20 min each) throughout 5 days. Aggression, defence and sniffing behaviours of both partners were recorded during each observation period using video camera. Social rank was detected by asymmetry in aggressive behaviour. It was shown that social hierarchy was established during the first four tests limited by the first 24 h after pairing. After this period aggression and defence behaviours were greatly decreased. After the first 5 tests a stabilization in aggression (number of wins, active attacks and not direct aggression) and defence (number of vertical defensive postures and escapes) as well as sniffing behaviours took place. But a strong asymmetry in mentioned here behaviours in males of different ranks (dominants and subordinates) was kept up. Thus we offer a new experimental model of minimal society, which entirely reproduces a pattern of establishment and maintenance of social hierarchy. Our model demonstrates significant differences in agonistic, defence and sniffing behaviours between males of different social rank.