Plasma progestagens in pregnant mares.

This research paper analyzes the quantities of published progesterone levels, using a competitive protein-binding assay, in the peripheral plasma of pregnant horses throughout their pregnancy.

Research Methodology

• The researchers used peripheral plasma specimens from pregnant mares. These samples were gathered throughout the gestation period for examinations.
• They used a competitive protein-binding assay method to measure the circulating progesterone levels in the plasma.
• The level of progesterone was monitored and recorded at specific intervals during pregnancy, such as Days 0 and 8, Days 28 and 44, Day 64, Day 300, and ultimately the day after birth (foaling).
• They also identified levels of 17alpha-hydroxyprogesterone, as well as two unknown compounds that were detectable during chromatographic analysis on Sephadex LH-20 columns.

Research Findings

• The study observed a significant rise in progesterone levels between Day 0 and Day 8, and again between Days 28 and 44. The maximum level of progesterone was on Day 64.
• After Day 64, the progesterone level gradually reduced until about Day 300, after which it again started to increase during the last 30 days of the pregnancy, achieving a minimum value on the day after the birth.
• Very minimal quantities of 17alpha-hydroxyprogesterone were detected, mainly identifiable between Days 40 and 120 and during the last month of gestation.
• They reported an intriguing observation about two unidentified compounds, appearing first between the 30th and 60th days of gestation. These compounds increased until Day 300 and showed a substantial increase approximately 5 days before birth. Notably, these mysterious compounds were not detectable the day after the foal’s birth.

Implications of the Study

• The research presents a detailed timeline of the change in plasma progestagen levels in pregnant mares, enabling a deeper understanding of equine gestational hormonal changes.
• The conclusions could guide more effective veterinary care and monitoring for the health of both the mare and the foal before, during, and after pregnancy.
• The intriguing discovery of two unidentified compounds that fluctuated significantly in the latter stages of pregnancy suggests potential targets for future research, which could uncover further insights into equine reproductive science.