Amino Acids in the Uterine Luminal Fluid Reflects the Temporal Changes in Transporter Expression in the Endometrium and Conceptus during Early Pregnancy in Cattle

Abstract

In cattle, conceptus-maternal interactions are critical for the establishment and maintenance of pregnancy. A major component of this early interaction involves the transport of nutrients and secretion of key molecules by uterine epithelial cells to help support conceptus development during the peri-implantation period of pregnancy. Objectives were to: 1) analyze temporal changes in the amino acid (AA) content of uterine luminal fluid (ULF) during the bovine estrous cycle; 2) understand conceptus-induced alterations in AA content; 3) determine expression of AA transporters in the endometrium and conceptus; and 4) determine how these transporters are modulated by (Progesterone) P4. Concentrations of aspartic acid, arginine, glutamine, histidine, lysine, isoleucine, leucine, phenylalanine and tyrosine decreased on Day 16 of the estrous cycle but increased on Day 19 in pregnant heifers (P<0.05). Glutamic acid only increased in pregnant heifers on Day 19 (P<0.001). Asparagine concentrations were greater in ULF of cyclic compared to pregnant heifers on Day 7 (P<0.05) while valine concentrations were higher in pregnant heifers on Day 16 (P<0.05). Temporal changes in expression of the cationic AA transporters SLC7A1 SLC7A4 and SLC7A6 occurred in the endometrium during the estrous cycle/early pregnancy coordinate with changes in conceptus expression of SLC7A4, SLC7A2 and SLC7A1 (P<0.05). Only one acidic AA transporter (SLC1A5) increased in the endometrium while conceptus expression of SLC1A4 increased (P<0.05). The neutral AA transporters SLC38A2 and SLC7A5 increased in the endometrium in a temporal manner while conceptus expression of SLC38A7, SLC43A2, SLC38A11 and SLC7A8 also increased (P<0.05). P4 modified the expression of SLC1A1, -1A4, -1A5, -38A2, -38A4, -38A7, -43A2, -6A14, -7A1, -7A5 and -7A7 in the endometrium. Results demonstrate that temporal changes in AA in the ULF reflect changes in transporter expression in the endometrium and conceptus during early pregnancy in cattle, some of which are modified by P4.

Characterization of the Endometrial Transcriptome in Early Diestrus Influencing Pregnancy Establishment in Dairy Cattle after Transfer of In-Vitro Produced Embryos

“…A set of genes down-regulated in PR cows was enriched for the KEGG pathway valine, leucine and isoleucine degradation. Amino acids are important components of the histotroph 32 and are essential for conceptus elongation [33][34][35] . Bovine embryos utilize amino acids 34,36 , and the concentrations of Lleucine, L-valine and L-isoleucine increase in pregnant animals 34,37 .…”

“…Amino acids are important components of the histotroph 32 and are essential for conceptus elongation [33][34][35] . Bovine embryos utilize amino acids 34,36 , and the concentrations of Lleucine, L-valine and L-isoleucine increase in pregnant animals 34,37 . We speculate that the early inhibition of endometrial genes involved in degradation of these amino acids would lead to a higher concentration of them during the implantation window, improving the endometrial receptivity.…”

Changes in the uterine metabolome of the cow during the first 7 days after estrus

“…Concentrations of amino acids in uterine fluid were largely greater than concentrations in blood serum (Fahning et al, ). In the cow, supplementation with progesterone increased endometrial expression of the amino acid transporter genes SLC1A1, SLC1A4, SLC7A1, SLC7A7, SLC38A7 , and SLC43A14 on Day 7 of the estrous cycle while decreasing expression of SLC1A5 (Forde et al, ). Similarly, manipulation of follicular growth to produce a large ovulatory follicle increased endometrial expression of SLC6A6, SLC7A4, SLC17A5, SLC38A1 , and SLC38A7 on Day 4 of the estrous cycle (França et al, ).…”

Understanding the uterine environment in early pregnancy in cattle: How have the omics en-hanced our knowledge?

“…For this reason Forde et al (2014b), in brief, analysed en masse the amino acid composition of beef heifer uteri which had been inseminated (n = 59) vs. a non-inseminated cyclic control group (n = 24) on days 7, 10, 13, 16 or 19 of pregnancy and days 7, 10, 13, or 16 of cyclic animals. Whilst several differences between the two groups were observed, when both pregnancy and day effects were considered, only differences in threonine, glutamate, and valine flux in ULF were observed, thus offering scope for targeted experimentation into the role of these amino acids in day 7-19 embryo development.…”