Conception and early pregnancy in the mare: lipidomics the unexplored frontier.

Lipids are dynamic biological molecules that play key roles in metabolism, inflammation, cell signalling and structure. They are biologically significant in the physiology of conception and reproduction. Many of the mechanisms surrounding equine conception and the early feto-maternal dialogue are yet to be understood at a biochemical level. Recently, lipidomic technologies have advanced considerably and analytical strategies have been enhanced and diversified. Consequently, in-depth lipidomic exploration now has the potential to reveal new lipid biomarkers and biochemical relationships that improve our understanding of the processes leading to efficient and successful reproduction. This review considers the role of lipids in conception and establishment of pregnancy, providing new insights into the enigmatic pathways governing early reproductive physiology of the mare. Lay summary: This paper discusses the role that lipids play in the very early stages of pregnancy in the mare. Lipids are microscopic non-soluble molecules that are important components of living cells. The manuscript discusses how lipids influence the reproductive cycle of mares, including ovulation and the detailed biological process of becoming pregnant. It explains how lipids are identified in a laboratory setting with a newly developing technology known as 'lipodomics'. The technology may lead to a more detailed understanding of how mares become pregnant. The focus of the paper is on mare reproduction, but it also draws on similarities with reproduction in other mammals. Remarkably there are gaps in much of our knowledge about the finer details of pregnancy in the horse, and the paper summarises what we already know about lipids, highlighting areas for further research.