Isolation, identification and quantitation of serum 5alpha-pregnane-3,20-dione and its relationship to progesterone in the pregnant mare.

The study focused on the isolation, identification, and quantitation of the substance 5alpha-pregnane-3,20-dione found in the serum of pregnant mares and its correlation with progesterone levels throughout gestation.

Isolation and Identification

• The researchers isolated 5alpha-pregnane-3,20-dione from a pooled sample of pregnant mare serum. The process they used is called Sephadex LH-20 column chromatography, which is a technique used to separate mixtures of molecules.
• The identity of the isolated compound was confirmed using radioimmunoassay, and further substantiated by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry analyses.
• They found that 5alpha-pregnane-3,20-dione was identifiable and separate from 5beta-pregnane-3,20-dione that wasn’t responsive to the radioimmunoassay system, nor could be detected by gas-liquid chromatography.

Correlation with Progesterone

• Peripheral blood levels of progesterone and 5alphs-pregnane-3,20-dione were tracked in four Quarter Horse mares for the first 150 days of gestation using radioimmunoassay.
• The progesterone and the 5alpha-pregnane-3,20-dione levels saw a decline from a range of 6 to 15 ng/ml at day 10 to between 2 to 8 ng/ml at day 40 of gestation.
• After day 40, both hormone concentrations started to increase. Interestingly, while progesterone levels tended to decline prior to the end of the 150 days of gestation, the levels of 5alpha-pregnane-3,20-dione were either maintained or elevated, with some observations as high as 35 ng/ml.

Limitations and Further Research

• The function or source of 5alpha-pregnane-3,20-dione in the serum of pregnant mares still remains unknown, demonstrating the need for further research.

This study sheds light on the hormonal profile of pregnant horses and provides intriguing perspectives on future research directions into the role of 5alpha-pregnane-3,20-dione in mare gestation.