Calf primary hepatocyte culture as a tool for anabolic steroid metabolism studies

Calf hepatocyte cultures were developed for the predictive analysis of in vivo xenobiotic biotransformations. The goal of this work was to show the feasibility of a system based on calf primary hepatocyte cultures using radiolabelled molecules to study xenobiotic metabolism rather than to study exhaustively the metabolism of a particular steroid. 19-Nortestosterone was chosen as a model substrate because of its relatively well known metabolism in the bovine species. Incubation of a mixture of tritiated and non-tritiated 19-nortestosterone was investigated in cell culture in order to target the biosynthesized metabolites. After extraction and purification, some of the in vitro metabolite structures were elucidated by GC-MS and compared with the main urinary metabolites detected in vivo after intramuscular injection of 19-nortestosterone into a calf. 19-Norepitestosterone, the main in vivo metabolite, was identified in vitro. However, the main in vitro metabolites were mostly in an oxidized form (4-estrene-3,17-dione, hydroxy-4-estrene-3,17-dione).