Chemoattractant properties of conditioned medium from equine corpora lutea collected at various stages of the oestrous cycle.

The research article is examining how cells in the equine ovary behave at different stages of the female horse’s oestrous cycle, with a focus on the involvement of these cells in inducing inflammation.

Research Objective

The aim of the research was to understand if the tissue of the corpus luteum (CL) in horses contributes to the significant increase of white blood cells (leucocytes) seen during natural and artificially induced luteal regression – a part of the oestrous cycle where the corpus luteum decreases in size and function.

• Corpora lutea are structures involved in hormone production within the ovaries, going through phases of growth and regression over the female hormonal cycle.
• Luteal regression is an important process in the oestrous cycle of mammals which, if impaired, can lead to fertility issues.

Methodology

CLs were collected at different stages of the dioestrus period and after application of a treatment with Prostaglandin F2alpha (PGF2alpha), a hormone playing a key role in the reproductive cycle of animals.

• The dioestrus period is a phase in the oestrous cycle when the CL is fully functional and produces progesterone, a hormone necessary for maintaining pregnancy.
• The PGF2alpha treatment is used to induce luteal regression prematurely, allowing the scientists to compare natural and artificially induced regression phases.

The research team harvested culture medium – the liquid in which the luteal tissue was incubated – after a 20-hour incubation period. This medium was then evaluated for its chemotactic properties, i.e its ability to attract certain types of white blood cells.

Results

Their findings showed that the conditioned medium was able to attract polymorphonuclear and mononuclear cells – types of white blood cells – in the later stage of dioestrus. This happened before functional regression of the CL, as well as after natural or induced regression. However, medium from midluteal tissue did not show this white blood cell attracting capacity.

• This is the first study to show that luteal tissues in horses can attract inflammatory cells actively in a simulated environment.

Conclusions

The researchers speculate that this early influx of inflammatory cells might actively participate in luteal regression. The exact chemical factors causing this chemotactic effect remain unidentified, yielding opportunities for further research.

• Knowing more about these factors could be useful for treating fertility issues in mammals that relate to regression of the corpus luteum.