In vitro metabolic studies using homogenized horse liver in place of horse liver microsomes.

This study demonstrates the use of homogenized horse liver as a viable alternative to liver microsomes for in vitro metabolic studies on drugs, specifically steroids. The authors found that using homogenized horse liver, aside from being simpler in preparation, also provides a cleaner extract and detects additional in vivo metabolites – making it a more effective approach.

Background of the Research

• The research, conducted in a laboratory that specializes in studying the metabolism of drugs – particularly steroids – utilises both in vitro (outside of a living organism) and in vivo (within a living organism) methods.
• Typically, in vitro metabolic studies employ the use of a microsomal fraction derived from the liver of a horse. However, this process is considered difficult and time-consuming.
• There is also a risk when isolating liver microsomes as it involves high-speed centrifugation, which may lead to losing enzymes important in phase I metabolism.
• These complications have incited the possibility of using homogenized horse liver as a simpler alternative that also enhances the correlation between in vitro and in vivo results.

Methods and Findings

• The researchers homogenized a necessary amount of horse liver, without any further purification before use.
• They found the cleanliness of this extract, tested through Gas Chromatography-Mass Spectrometry (GC-MS) analysis, to be on par with liver microsomes.
• In vitro experiments were carried out using the homogenized horse liver on five anabolic steroids – Turinabol, Methenolone Acetate, Androst-4-ene-3,6,17-trione, Testosterone, and Epitestosterone.
• The results detected not just previously reported in vitro metabolites, but also other known in vivo metabolites that exist in the horse.

Significance of the Study

• This is a first-of-its-kind study that documents the successful use of homogenized horse liver for in vitro metabolism experiments.
• The study validates an alternative method that was simpler but still maintained a similar level of cleanliness for the extract obtained.
• A broader range of metabolites, including those detected in in vivo studies, were also found using this new model, potentially augmenting the fidelity of in vitro testing in relation to in vivo results.