Moderate Differences in Plasma Leptin in Mares Have no Effect on Either the Amino Acid or the Fatty Acid Composition of the Uterine Fluid.

This study examines the effects of differing levels of the hormone leptin in the blood (circulating leptin) of female horses on the composition of fatty acids and amino acids in their reproductive organ fluids (uterine fluid). The finding of the study reveals that the specific fatty acid and amino acid composition in the uterine fluid does not seem to be affected by the concentration of leptin in the blood within normal physiological ranges.

Objectives and Methodology

• The goal of the study was to investigate the link between circulating leptin and the fatty acid (FA) and amino acid (AA) composition of the equine uterine fluid (UF) and peripheral blood plasma (BP).
• The researchers used a technique based on mass spectrometry to perform these investigations.
• Fluid samples were collected on the 6th and 7th days following ovulation from ten broodmares which were retrospectively grouped according to their blood plasma leptin concentrations.

Findings

• Significant metabolic differences were found in the amino and fatty acid compositions of blood plasma and uterine fluid.
• In blood plasma, the leading fatty acids were stearic, palmitic, and linoleic acid. However, in uterine fluid, the most abundant fatty acids were eicosapentaenoic, arachidonic, and stearic acid.
• In terms of amino acids, glycine, glutamine, serine and alanine dominated the profile of blood plasma, and were also highly abundant in the uterine fluid.
• The most abundant amino acid in the uterine fluid was glutamic acid.

Conclusion

• The primary finding is that variations in blood plasma leptin concentration within normal physiological range do not seem to influence the specific fatty acid or amino acid constitution of the uterine fluid.
• This suggests that the composition of the uterine fluid may be regulated locally rather than by peripheral metabolic hormones like leptin.