Nodal Promotes Functional Luteolysis via Down-Regulation of Progesterone and Prostaglandins E2 and Promotion of PGF2α Synthetic Pathways in Mare Corpus Luteum.

This research investigates the role of a molecule called Nodal in the process of luteolysis in horses. That is, it explores how Nodal affects the breakdown of progesterone and the enhancement of a hormone called PGF2α, which impact the ovulation cycle in mares.

Background of the Study

• The study explores the role of a molecular pathway that involves Nodal in the process called luteolysis, which refers to the degradation of the corpus luteum—a temporary endocrine structure in female mammals.
• Nodal is known as an embryonic morphogen that belongs to the TGFβ superfamily, which plays key roles in embryogenesis and cellular differentiation.
• The researchers specifically wanted to understand how this pathway acts on the corpus luteum secretory activity using equine, or horse, cells as their test model.

Experiments and Findings

• The researchers found that Nodal and its receptor molecules were located in small and large luteal cells and certain endothelial cells—cells that line the inside of blood vessels.
• They noted that the concentrations of Nodal and one of its receptors, Alk7, were highest at the initiation of luteolysis, while other receptors increased later on in the process.
• When Nodal was applied to luteal cells, it decreased the concentrations of progesterone—a hormone important in pregnancy and menstruation—and prostaglandin E2, both crucial factors in the ovulation cycle.
• Conversely, the same treatment led to an increased secretion of another hormone called PGF2α, which usually rises during the menstruation phase when the body stops maintaining the environment for a fertilized egg.
• This occurred through a greater expression of certain genes that synthesize PGF2α.
• The researchers also found that the introduction of PGF2α induced the greater production of Nodal protein and other related molecules.

Conclusions

• The team concluded that Nodal significantly decreased the production of progesterone and increased the production of PGF2α more than either Nodal or PGF2α did alone.
• These findings highlight the specific mechanisms through which the Nodal signalling pathway contributes to functional luteolysis in horses—providing deep insights into ovulation and possibly pointing to new strategies to control animal fertility.