Studies related to the metabolism of anabolic steroids in the horse: the metabolism of 1-dehydrotestosterone and the use of fast atom bombardment mass spectrometry in the identification of steroid conjugates.

The research article discusses a study about the metabolism and urinary excretion of 1-dehydrotestosterone in gelded horses and how modern mass spectrometry techniques help with identifying steroid conjugates.

Understanding the Metabolism and Urinary Excretion of 1-dehydrotestosterone

• The first part of the research investigates how anabolic steroids, specifically 1-dehydrotestosterone, metabolizes in the body of gelded horses. Gelded horses are male horses that have been castrated, meaning they no longer possess the capability to produce testosterone.
• Findings from the research show that about 40% of the intake of this steroid excretes from the body in a span of 24 hours. Researchers used Amberlite XAD-2 resin to extract the metabolized components from urine samples.
• The extracted metabolites were then separated into two groups – glucuronides and sulphoconjugates. Upon inspecting these two groups of metabolites using gas chromatography mass spectrometry, it was found that 1-dehydrotestosterone remained unchanged only within the sulphoconjugates.

Using Mass Spectrometry to Study Steroid Conjugates

• The latter part of the research discusses the use of Fast Atom Bombardment (FAB) mass spectrometry to study the structure of steroid conjugates. FAB is a method of ionization in mass spectrometry that is used to analyse samples that do not easily ionize.
• Both positive and negative ion fast atom bombardment mass spectra were obtained on the purified 1-dehydrotestosterone sulfoconjugate, which was isolated from horse urine, as well as the alkali metal salts of three standard steroid conjugates.
• The spectra acquired in both positive and negative ion modes were found to be of comparable intensity. The positive ion spectra were generally more complex, mainly because of the formation of alkali metal adduct ions which contain several sodium cations.
• Nevertheless, the most abundant ion in the negative ion spectra corresponded to the loss of the alkali metal cation giving [M]-. This means that despite its complexities, the structure of a steroid conjugate can still be determined by combining different mass spectrometric techniques.