Identification of testosterone sulfate in the plasma of the male lizard Tiliqua rugosa

Plasma (solvolyzed and unsolvolyzed) from the male lizard Tiliqua rugosa was analyzed using gas chromatography, high-performance liquid chromatography (HPLC), and mass spectroscopy. HPLC with electrochemical detection was also used to characterize ketosteroid conjugates. Testosterone was identified in the solvolyzed plasma extract, and a compound corresponding to testosterone sulfate was detected in unsolvolyzed extracts. Concentrations were approximately 500 nmol/liter in intact male plasma, less than 100 nmol/liter in castrates, and undetectable in female plasma. Steroid glucuronides appeared to be absent from plasma. Epitestosterone conjugates were not detected, although the free steroid is found in high concentrations in T. rugosa. The presence of testosterone sulfate in the blood of T. rugosa may indicate a possible role for sulfoconjugates in controlling the availability of biologically active androgens.