Pulsatile secretion of luteinizing hormone and progesterone in mares during the estrous cycle and early pregnancy.

The research examines a possible relation between the secretion patterns of progesterone and luteinizing hormone (LH) in pregnant and non-pregnant mares. It’s found that both hormones are secreted in a pulsatile manner, but with little temporal relation.

Objective of the Study

• The study aimed to investigate whether there is an ultradian variation in serum progesterone concentration, and the relationship between the secretory patterns of progesterone and luteinizing hormone in nonpregnant and pregnant mares.

Methodology

• Blood samples were collected every 15 minutes over a 24-hour period. This was done on the 8th day of the estrous cycle for non-pregnant mares and on the 18th day of pregnancy for expectant ones.
• The progesterone and LH concentrations on these samples were then measured using a radioimmunoassay, an in-vitro procedure that quantifies or identifies antigens or antibodies.

Findings

• The study discovered that in both pregnant and non-pregnant mares, progesterone was secreted in a pulsatile (rising and falling) manner. This means the hormone levels varied at intervals.
• Similarly, the luteinizing hormone was found to be secreted in a pulsatile manner across the two groups of mares.
• Despite these similar patterns, the study further revealed there was little temporal relation between the pulses of LH and progesterone in both pregnant and nonpregnant mares. This means the secretion of these two hormones does not appear to be synchronously timed.