Dynamics of lipid droplets in the endometrium and fatty acids and oxylipins in the uterine lumen, blood, and milk of lactating cows during diestrus

• Published in: Journal of dairy science Vol. 104; no. 3; p. 3676
• Main Authors: King, K, Ticiani, E, Sprícigo, J F W, Carvalho, M R, Mion, B, Bertolini, M, Contreras, G A, Ribeiro, E S
• Format: Journal Article
• Language: English
• Published: United States 01-03-2021
• Subjects: Animals; Cattle; Diestrus; Endometrium; Fatty Acids; Female; Lactation; Lipid Droplets; Milk; Oxylipins; Pregnancy; Uterus; fatty acid; dairy cow; oxylipin; uterus; lipid; fertility
• ISSN: 1525-3198
• DOI: 10.3168/jds.2020-19196

Our objective was to investigate the lipid content of uterus, blood plasma, and milk at early, mid, and late diestrus. Lactating cows (n = 30) had the estrous cycle and ovulation synchronized by administration of exogenous hormones. Cows were blocked by parity and assigned randomly to receive transcervical uterine flushing and biopsy on d 5 (early diestrus), 10 (mid diestrus) or 15 (late diestrus) of the estrous cycle. Flushing and endometrial biopsy were performed in the uterine horn ipsilateral to the corpus luteum. The recovered flushing was used for analyses of lipid composition by liquid chromatography-tandem mass spectrometry and the biopsy was used for investigation of lipid droplet abundance in endometrial cryosections using a neutral lipid fluorescent dye. In addition, blood and milk samples were collected from all cows on d 5, 10, and 15. All blood samples were used to measure the concentration of progesterone in plasma, and all milk samples were used to determine milk composition. Subsamples of blood plasma and milk were also used to evaluate the composition of fatty acids and oxylipins using the same methodology used for uterine flushing samples. The abundance of lipid droplets in the endometrium increased 1.9-fold from d 5 to 10, and 2-fold from d 10 to 15. Concentration of long-chain fatty acids and oxylipins in uterine flushing were, on average, 2.2 and 2.5 times greater in samples collected on d 15 compared with those collected on d 5 and 10. These differences were not observed in blood and milk, suggesting that accumulation of fatty acids and oxylipins in the uterus is regulated locally. In addition to concentration, the profile of individual fatty acids and oxylipins in uterine lumen changed substantially during diestrus. The main categories with increased abundance at late diestrus were mono- and polyunsaturated fatty acids, and oxylipins derived from arachidonic acid, dihomo-γ-linolenic acid, and docosahexaenoic acid. In conclusion, fatty acids and oxylipins accumulate in the uterine lumen during diestrus and might work as a mechanism to supply these lipids to the developing conceptus at late diestrus, when the onset of elongation occurs and substantial synthesis of biomass and cell signaling by lipid mediators are required.