DEVELOPMENT AND VALIDATION OF A FECAL TESTOSTERONE BIOMARKER IN MUS MUSCULUS AND PEROMYSCUS-MANICULATUS

This is a report on the development and validation of an ELISA method to determine fecal testosterone levels, and on their evaluation as a b iomarker for adverse effects of endocrine-disrupting chemicals on repr oductive health using male rodents of the Peromyscus maniculatus and M us musculus species as an animal model. The ELISA antibody had the hig hest specificity for testosterone (100%), followed by dihydrotestoster one (57.4%) and androstenediol (0.27%). Radiolabeled testosterone was injected i.p. into three mice. Fecal samples were collected, extracted , and analyzed by liquid scintillation counting. The ELISA was perform ed to characterize the excretion kinetics and metabolic fate of circul ating testosterone. Solubilization of feces with 10% methanol overnigh t provided an extraction efficiency of 87% for all metabolites; an eth yl ether extraction was more selective for testosterone. The fecal exc retion of the testosterone was a biphasic process with a majority of t he radioactivity recovered in the first 24 hours. HPLC analysis reveal ed at least five testosterone metabolites in feces, with most metaboli tes being less polar than testosterone. This study forms the initial e valuation of what will become a field monitoring tool.