Biosynthesis of 3 beta-hydroxy-5,7-pregnadien-20-one by the horse fetal gonad.

This study analyses the unique process in which pregnant horses produce the estrogen hormone elevin and other similar hormones. Using radioactive labelling techniques, the research shows that these hormones are created through a pathway distinct from the typical cholesterol-derived process seen in most mammals. It suggests an interplay between the horse’s fetal gonad and the placenta in hormone synthesis.

Unique Biosynthesis Pathway in Pregnant Mares

• The research highlights an unique aspect of pregnant mare’s hormonal system, where estrogens like elevin are synthesized not from cholesterol, a common precursor in hormonal biosynthesis, but through an alternative pathway. This constitutes an exception in the animal kingdom.

Experiments with Fetal Horse Gonads

• The investigators conducted experiments with fetal horse gonads by incubating them with tritiated sodium acetate, which is a type of isotope-labelled sodium acetate for tracing chemical reactions.
• A result of this experiment was the detection of two chemically pure hormones, namely 3 beta-hydroxy-5,7-pregnadien-20-one and 3 beta-hydroxy-5,7-androstadien-17-one. These two hormones play a crucial role in the unique biosynthesis pathway.

Fetal Gonad-Placental System For Hormone Production

• The research paper suggests a two-step hormonal production system in pregnant mares, where the progestogen hormone 3 beta-hydroxy-5,7-pregnadien-20-one is produced in the fetal gonad.
• This hormone then serves as precursor for the production of androgenic hormone 3 beta-hydroxy-5,7-androstadien-17-one, also in the fetal gonad.
• 3 beta-hydroxy-5,7-androstadien-17-one further serves as precursor of equilin, an estrogen, in the placenta of the pregnant mare.

Potential Precursor of 3 beta-hydroxy-5,7-pregnadien-20-one

• While the paper outlines this special biosynthesis pathway, it also raises discussion about what could be the possible precursor of 3 beta-hydroxy-5,7-pregnadien-20-one. This opens up new avenues of investigation to fully understand this unique and rare biosynthesis pathway in horses.