Role of genotype, social stress, and season in the regulation of hormonal function of testes incubated in vitro in mice

Micropopulations consisting of six male mice of different genotypes were st udied (each of lines A/He, CBA/Lac, C57BL/6J, DD, YT, and PT was represente d by one male). Interlinear differences in the level of social dominance an d the effects of genotype, social hierarchy, and season on in vitro testost erone production by testes were examined under different incubation conditi ons. The testosterone production was estimated under control conditions and under stimulation with human chorionic gonadotropin (CG). Significant gene tic differences in the initial and CG-stimulated testosterone production by testes incubated in vitro were found. By the control production, the genot ypes fell into two groups: lines C57BL/6J, A/He, and CBA/Lac had low produc tion of the hormone; lines YT, PT, and DD, high production. By responsivene ss 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, li ne PT, intermediate production; and line PT, high production. The obtained data indicate stability of genetic polymorphism for the responsiveness of t estes to gonadotropins, because neither season nor the formation of social hierarchy could significantly change the interlinear differences. In line P T characterized by high hormonal activity of gonads in the control and unde r stimulation with gonadotropins, males became dominant in a significantly greater number of cases studied during the formation of hierarchy in microp opulations. The dynamics of both control production of a male sex hormone a nd responsiveness of testes to CG was established in vitro during the forma tion of social hierarchy; the effects of season on this dynamics were revea led. Specific characteristics of secretory activity of testes were detected in the control and under stimulation with gonadotropins, depending on incu bation conditions. Seasonal and genotypic characteristics of the responsive ness of testes to CG were revealed under different incubation conditions. G enotypic characteristics indicate interlinear differences in the degree of inertia of testosterone biosynthesis on exposure to gonadotropins.