Genotypic Peculiarities of Olfactory Communication in Male Laboratory Mice (Mus musculus) in a Social Competition Model

Abstract

Chemocommunication plays an important role in establishing and maintaining the spatial ethological structure of the population. Previously, we demonstrated that the propensity to social dominance in male laboratory mice is mainly determined by an individual’s genotype. However, it remains unclear whether genotypic peculiarities of mouse olfactory communication, the most important links of which are marking behavior and olfactory contacts, are associated with the ability to occupy a high social rank in the hierarchical structure of the community? The aim of the present work was to establish the effect of genotype on the intensity of marking behavior and olfactory contacts in male laboratory mice in a social competition model and to study the association of these types of social behavior with a hereditary predisposition to dominance. This study was conducted on adult males of inbred mice strains BALB/cLac, CBA/Lac, and PT differing in the propensity to dominate: BALB/cLac and PT males mainly dominated CBA/Lac males. The experimental groups were formed out of two males of different genotypes in three possible pairwise combinations. The intensity of urine marking the territory was estimated for each male in conditions of social isolation and after pair keeping during the period of stable dominant–subordinate relations. Olfactory contacts that were naso-nasal and naso-anogenital sniffing were used as an additional indicator of the propensity of mice to olfactory communication in conditions of social competition. Hereditary differences in the intensity of urine marking and in the frequency of olfactory contacts were established in male laboratory mice in the social competition model: dominant males of the CBA/Lac strain marked the territory and sniffed the opponent more frequently than dominants of the BALB/cLac and PT strains, while a decrease in urine marking and olfactory activity was observed in subordinate males of these strains. During social isolation, males of the CBA/Lac strain also marked the territory more frequently than males of the two other strains. Thus, the male mice of different inbred strains differ in the intensity of urine marking and olfactory behavior, which can be modified by external conditions, for example, social rank of an individual, and the intensity of urine marking and olfactory activity does not predict the social rank of an individual.