Sex-specific androgen binding in spotted hyaena (Crocuta crocuta) plasma

1. A charcoal adsorption assay demonstrated a large variance in androgen binding ability in female spotted hyaenas. 2. A positive correlation between plasma androgen binding ability and ovarian steroid concentrations was demonstrated in adult females. 3. The strong plasma binding affinity for testosterone and dihydrotestosterone (DHT) (nM) together with the lack of cortisol and weaker oestradiol-17 beta binding suggests that a specific androgen binding substance, possibly a protein, is present in adult females of this species. 4. The lack of high affinity binding in male spotted hyaenas is unusual and deserves further investigation. 5. Some androgen binding in all, including males and immature animals suggests that albumin may bind some plasma androgens in this species.