Phenogenetic analysis of testicular responsiveness to chorionic gonadotropin in inbred mouse strains

Genetic differences in the testicular hormonal responsiveness to in vivo administration of chorionic gonadotropin (CG) between adult male mice of eight inbred strains (A/Sn, CBA/Lac, CC57Br, C57Bl/6J, DBA/2J, GR, PT, and YT) were determined. In addition, the genetic variation of the body and testis weights was estimated as related to the responsiveness to stimulation of steroidogenesis with CG. Adult males were subcutaneously injected with 10 IU of CG or physiological saline 120 min before decapitation. It was found that the baseline testosterone level in the blood serum and its content in the testes only slightly varied in males of the strains studied. Administration of CG increased these parameters by a factor of 3-45, depending on the strain. The results of the study indicate genetic differences in the testicular reactivity to CG. In addition, it has been found that the response to administration of CG, as compared to the baseline levels, provides the most reliable information on the genetic characteristics of the hormonal potential of the testes. The given set of inbred mouse strains may be a promising genetic model for studying the physiological and hereditary variations of testicular steroidogenesis.