The source of the 5-alpha-pregnanes that occur during gestation in mares.

This research provides insights into the sources of 5-alpha-pregnanes that occur during late pregnancy in mares. These compounds, believed to be derived from the placenta, fetus, or mare, were examined through injections into the uterine artery or umbilical vein, and subsequent monitoring of plasma levels for up to six hours.

Research Methodology

• The researchers used [1,2,6,7-3H]Progesterone, a labeled form of progesterone, for injections into the uterine artery or the umbilical vein of four pregnant mares (Ponies).
• The study aimed to determine the source of three 5 alpha-pregnanes: DHP, 20 alpha-ol, 3 beta-ol.
• Following the injections, plasma samples were collected from indwelling catheters in the uterine artery and vein and the umbilical artery and vein frequently, up to six hours after the injections.
• These plasma samples were then extracted with organic solvents and the respective pregnanes were isolated by thin-layer chromatography, a technique for separating non-volatile mixtures.

Key Findings

• The plasma levels of radioactive DHP in the umbilical vein were significantly greater than those in the umbilical artery but showed similarity with the levels in the uterine artery and vein. This suggests that DHP may have been produced by the placenta and also another maternal source.
• On the other hand, plasma levels of radioactive 20 alpha-ol in the umbilical artery and vein were significantly lower than those in the uterine artery but were similar to levels found in the uterine vein. This suggests that 20 alpha-ol primarily originates from the mare (mother).
• Finally, the levels of radioactive 3 beta-ol in the umbilical artery were higher than those found in the uterine artery and vein but were similar to those in the umbilical vein. This indicates that 3 beta-ol was mainly produced by the fetus.

In conclusion, the results from this research provide important insights into the origins of certain compounds during late pregnancy in mares. These findings may prove useful in enhancing our understanding of equine reproduction and could potentially lead to improvements in equine prenatal care.