Is FAS/Fas ligand system involved in equine corpus luteum functional regression?

The research article explores the role of Fas ligand (FASL) and its receptor FAS in the functional regression of the corpus luteum in horses. It specifically investigates their presence in the corpus luteum throughout the luteal phase and their influence on the production of luteotrophic and luteolytic factors, cell viability, and apoptosis.

Research Objectives and Methods

• The main aim of this study was to find out if FASL and FAS, proapoptotic factors from the tumor necrosis factor superfamily, are present in the mare’s corpus luteum during the luteal phase. This was measured through Western blotting and real-time PCR assays.
• The secondary goal was to identify the influence of FASL singly, or alongside cytokines such as tumor necrosis factor alpha (TNF) and interferon gamma (IFNG), on the equine cell production of luteotrophic (maintenance of the corpus luteum) and luteolytic factors (trigger the degradation of the corpus luteum), cell viability and apoptosis.

Key Findings

• The presence of FASL and FAS were established in the equine corpus luteum in all stages of the luteal phase.
• The presence of FASL and FAS were particularly noticeable in large steroidogenic and endothelial CL cells throughout the luteal phase, as shown by immunohistochemistry.
• FASL had a significant impact on the in vitro production of progesterone and prostaglandin E(2) (PGE(2)) by equine luteal cells, and also increased the production of prostaglandin F(2alpha) (PGF(2alpha)). Additionally, the impact of FASL on cell viability was dependent on the presence of TNF and IFNG, reinforcing their interconnected influence on cell behavior.

Conclusion

• The study demonstrates the presence of FASL and FAS in the corpus luteum of horses and suggests their important role in the process of functional luteolysis, the degradation of the corpus luteum. This indicates that these proteins might contribute to the regulation of the reproductive cycle in mares.