The objective was to characterize the effects of Escherichia coli lipopolysaccharide (LPS) endotoxin (given i.v.) on luteal structure and function. Seven nonlactating German Holstein cows, 5.1G0.8 years old (meanGS.E.M.), were given 10 ml saline on day 10 (ovulationZ day 1) of a control estrous cycle. On day 10 of a subsequent cycle, they were given 0.5 mg/kg LPS. Luteal size decreased (from 5.2 to 3.8 cm 2 , P%0.05) within 24 h after LPS treatment and remained smaller throughout the remainder of the cycle. Luteal blood flow decreased by 34% (P%0.05) within 3 h after LPS and remained lower for 72 h. Plasma progesterone (P 4 ) concentrations increased (P%0.05) within the first 3 h after LPS but subsequently declined. Following LPS treatment, plasma prostaglandin (PG) F metabolites concentrations were approximately tenfold higher in LPS-treated compared with control cows (9.2 vs 0.8 ng/ml, P%0.05) within 30 min, whereas plasma PGE concentrations were nearly double (P%0.05) at 1 h after LPS. At 12 h after treatment, levels of mRNA encoding Caspase-3 in biopsies of the corpus luteum (CL) were increased (P%0.05), whereas those encoding StAR were decreased (P%0.05) in cattle given LPS vs saline. The CASP3 protein was localized in the cytoplasm and/or nuclei of luteal cells, whereas StAR was detected in the cytosol of luteal cells. In the estrous cycle following treatment with either saline or LPS, there were no significant differences between groups on luteal size, plasma P 4 concentrations, or gene expression. In conclusion, LPS treatment of diestrus cows transiently suppressed both the structure and function of the CL.

When given intravenously (iv), lipopolysaccharide (LPS) transiently suppresses the structure and function of the bovine corpus luteum (CL). This is associated with increased release of prostaglandin (PG) F 2a metabolite. The underlying regulatory mechanisms of this process remain, however, obscure. Therefore, the aims of this study were: i) to investigate the expression of the LPS receptor toll-like receptor 4 (TLR4) and 2 (TLR2) in the bovine CL during early, mid-and late luteal phases; and ii) to further dissect the mechanisms of LPS-mediated suppression of luteal function. As revealed by semi-quantitative qPCR and immunohistochemistry, both receptors were detectable throughout the luteal lifespan. Their mRNA levels increased from the early toward the mid-luteal phase; no further changes were observed thereafter. The TLR4 protein seemed more highly represented than TLR2. The cellular localization of TLRs was in blood vessels; weaker signals were observed in luteal cells. Additionally, cows were treated either with LPS (iv, 0.5 mg/kg BW) or with saline on Day 10 after ovulation. Samples were collected 1200 h after treatment and on Day 10 of the respective subsequent (untreated) cycle. The mRNA expression of several possible regulatory factors was investigated, revealing the suppression of PGF 2a receptor (PTGFR), STAR protein and 3b-hydroxysteroid dehydrogenase, compared with controls and subsequent cycles. The expression of TLR2 and TLR4, interleukin 1a (IL1A) and 1b (IL1B) and of PGF 2a and PGE 2 synthases (HSD20A and mPTGES respectively) was increased. The results demonstrate the presence of TLR2 and TLR4 in the bovine CL, and implicate their possible involvement in the deleterious effects of LPS on its function.

Background: Disturbed uterine involution impairs ovarian function in the first weeks after calving. This study analyzed the long-term effect of metritis on luteal function of 47 lactating Holstein-Friesian cows during the first four postpartum estrous cycles. Cows with abnormal uterine enlargement and malodorous lochia were classified as having metritis (group M, n = 18), and all others were considered healthy (group H, n = 29). Luteal size was measured once between days 9 and 13 of the first (group H, n = 11; group M, n = 12), second (group H, n = 23; group M, n = 18) and fourth (group H, n = 11; group M, n = 7) postpartum luteal phases. Serum progesterone concentration was measured at the same time. Sixteen cows (group H, n = 9; group M, n = 7) underwent transvaginal luteal biopsy for gene expression analysis of steroidogenic regulatory proteins during the second and fourth cycles. Cows with persistence of the corpus luteum (CL) underwent determination of luteal size, luteal biopsy and serum progesterone measurement once between days 29 and 33, followed by prostaglandin treatment to induce luteolysis. The same procedures were repeated once between days 9 and 13 of the induced cycle.

Abstract. Persistence of the corpus luteum (CL) in cattle usually occurs during the puerperium and is associated with interference of prostaglandin (PG) F 2α release from the uterus. The objective of the present study was to determine for the first time the gene expressions in the persistent CL compared with the CL of pregnancy and cyclic CL. Three types of CL biopsy samples were collected from 32 lactating Holstein cows: (1) CL persisting for 29 to 33 days after the first ovulation postpartum (persistent CL, n=9), (2) CL between days 29 and 33 of early pregnancy (CL of pregnancy, n=8) and (3) CL between days 10 and 13 of the estrous cycle (cyclic CL, n=27). mRNA expression of 2′,5′-oligoadenylate synthetase-1 was upregulated only in the CL of pregnancy, confirming exposure to interferon-τ (IFNT) produced by trophoblasts in pregnant cows. mRNA expressions of immune tolerance-related factors (PGES and forkhead/winged helix transcription factor 3) were upregulated in the CL of pregnancy but not in the persistent CL, suggesting that IFNT controls upregulation of these genes. mRNA expression relating to some of the major systems such as lymphangiogenesis, inflammation and apoptosis were similarly upregulated in the persistent CL and the CL of pregnancy but not in the cyclic CL. The results suggest that the persistent CL may survive for a long period without changes in local immune tolerance but develops several major systems required for CL maintenance similar to the CL of pregnancy. Key words: Dairy cow, Early pregnancy, Persistent corpus luteum, mRNA expression (J. Reprod. Dev. 58: [445][446][447][448][449][450][451][452] 2012) I n mammals, the corpus luteum (CL) develops rapidly after ovulation and plays a crucial role in survival of the embryo and maintenance of pregnancy by producing progesterone (P4). Luteinization of steroidogenic cells and angiogenesis are essential processes during CL development and maturation [1]. On the other hand, prostaglandin (PG) F 2α released by the uterine endometrium induces regression of the CL if pregnancy is not established. Formation, maintenance and regression of the CL are regulatory mechanisms controlled by various luteotropic and luteolytic factors that are mediated by the cyclic expression of key genes during the lifespan of the CL [2].Luteolysis in cattle is generated by the pulsatile release of PGF 2α by the endometrium between days 16 and 19 of the estrous cycle [3]. The persistence of the CL in cattle usually occurs postpartum in association with uterine disorders, such as fetal mummification, endometritis or pyometra [4]. In addition, mastitis [5] and negative energy balance [6] can cause a higher incidence of a prolonged luteal phase. It is generally thought that interference with the production or release of PGF 2α causes persistent CL [7]. Indeed, the lifespan of the CL can be prolonged for at least 145 days by immunization against PGF 2α , thereby maintaining plasma P4 concentrations above 4 ng/ ml [8]. Although a prolonged luteal phase due to CL persistence i...

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