MPIDR Working Paper

High maternal androstenedione levels during pregnancy in a small precocial mammal with female genital masculinisation

Kraus, C., Pfannkuche, K. A., Trillmich, F., Groothuis, T. G. G.
MPIDR Working Paper WP-2008-017, 23 pages.
Rostock, Max-Planck-Institut für demografische Forschung (März 2008)
Open Access

Abstract

-Masculinisation of female genitalia is an intriguing phenomenon amongst some mammalian species and its endocrinological basis as well as its adaptive value is still heavily debated. We recently reported female genital masculinisation in Cavia magna. The closely related C. aperea, does not show such masculinisation providing an unique opportunity to investigate potential endocrinological mechanisms underlying this difference. For both species we determined plasma levels of androstenedione and testosterone in adults of both sexes, and in females during different stages of pregnancy. Consistent with the normal mammalian pattern males showed higher levels of both androgens than conspecific females. Androgen profiles during pregnancy differed significantly between C. magna and C. aperea females: during mid-pregnancy androstenedione levels were strongly elevated in the masculinised C. magna, but not in C. aperea, indicating that high levels of this androgen may be involved in the differentiation of masculinized genitalia in female C. magna, as has been suggested for the spotted hyena. In both C. magna and the spotted hyena the pups show a highly advanced state of maturation, but in contrast to the hyena female C. magna are not overly aggressive. We therefore propose that female genital masculinisation might be a side effect of early exposure to elevated levels of maternal androgens that might be selected for to speed up precocial development.
Das Max-Planck-Institut für demografische Forschung (MPIDR) in Rostock ist eines der international führenden Zentren für Bevölkerungswissenschaft. Es gehört zur Max-Planck-Gesellschaft, einer der weltweit renommiertesten Forschungsgemeinschaften.