Role of Genotype, Social Stress, and Season in the Regulation of Hormonal Function of Testes Incubated in Vitro in Mice

Abstract

Micropopulations consisting of six male mice of different genotypes were studied (each of lines A/He, CBA/Lac, C57BL/6J, DD, YT, and PT was represented by one male). Interlinear differences in the level of social dominance and the effects of genotype, social hierarchy, and season on in vitro testosterone production by testes were examined under different incubation conditions. The testosterone production was estimated under control conditions and under stimulation with human chorionic gonadotropin (CG). Significant genetic differences in the initial and CG-stimulated testosterone production by testes incubated in vitro were found. By the control production, the genotypes fell into two groups: lines C57BL/6J, A/He, and CBA/Lac had low production of the hormone; lines YT, PT, and DD, high production. By responsiveness of gonads to CG, the genotypes fell into three groups: line CBA/Lac had low testosterone production by testes; lines C57BL/6J, A/He, YT, and DD, line PT, intermediate production; and line PT, high production. The obtained data indicate stability of genetic polymorphism for the responsiveness of testes to gonadotropins, because neither season nor the formation of social hierarchy could significantly change the interlinear differences. In line PT characterized by high hormonal activity of gonads in the control and under stimulation with gonadotropins, males became dominant in a significantly greater number of cases studied during the formation of hierarchy in micropopulations. The dynamics of both control production of a male sex hormone and responsiveness of testes to CG was established in vitro during the formation of social hierarchy; the effects of season on this dynamics were revealed. Specific characteristics of secretory activity of testes were detected in the control and under stimulation with gonadotropins, depending on incubation conditions. Seasonal and genotypic characteristics of the responsiveness of testes to CG were revealed under different incubation conditions. Genotypic characteristics indicate interlinear differences in the degree of inertia of testosterone biosynthesis on exposure to gonadotropins.