Search

Contents [ABSTRACT FROM AUTHOR]

In cattle, 17β-estradiol (E2) is essential for triggering luteolysis via the synthesis of prostaglandin F2α (PGF2α). We aimed to evaluate the effects of E2-treatment on day 15 of the estrous cycle on the transcript abundance of genes involved in the PGF2α synthetic cascade. Nelore heifers (N = 50) were subjected to a hormonal protocol for the synchronization of ovulation. Between days 14 and 23 after estrus, the area (cm 2 ) and blood perfusion (%) of the corpus luteum (CL) and progesterone (P4) plasma concentrations were evaluated daily. On day 15, the heifers were assigned to the Control (2 mL of pure sesame oil, N = 21) or Estradiol group (1 mg of E2 diluted in 2 mL of sesame oil, N = 23). After the treatments at 0 h, uterine biopsies were collected at times 1.5 h (C1.5h, N = 8 and E1.5h, N = 10) or 3 h (C3h, N = 8 and E3h, N = 11); and blood samples were obtained from 0, 3, 4, 6 and 7 h for the measurement of 13,14-dihydro-15-keto-PGF2α (PGFM) concentrations by ELISA. Transcript abundance was determined by RT-qPCR and protein abundance of ESRβ and OXTR was determined by Western Blotting. The Estradiol group showed greater (P < 0.05) concentrations of PGFM at 6 and 7 h compared to the Control group. A progressive decrease in plasma P4 concentrations characterized a hastened functional luteolysis, followed by structural luteolysis in the Estradiol group (P < 0.05). Among the treatment groups, no significant difference was detected for the abundance of PRKCα, PRKCβ, AKR1B1, PTGS2 and ESRα transcripts (P > 0.05). Estradiol treatment decreased the abundance of PLA2G4A, AKR1C4, and ESRβ both 1.5h and 3h after treatment (P < 0.05). The relative expression of PGR and OXTR was greater in E3h compared to the C3h (P > 0.05). Protein abundance did not differ between treatment groups at either experimental times (P > 0.05). Overall, E2 promoted an increase in PGFM concentrations and the hastening of functional and structural luteolysis in Nelore heifers through the upregulation of PGR and OXTR, demonstrating for the first time that the expression of these receptors within 3 h after E2 stimulus was associated with triggering luteolysis in cattle., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Traditionally, in vitro oocyte and embryo culture progresses through a series of varying culture medium. To investigate simplifying the in vitro production of bovine cumulus-oocyte complexes (COCs), this study used synthetic oviductal fluid (SOF) supplemented with conjugated linoleic acid (CLA). Special interest was placed on gene expression linked to lipid metabolism and oocyte maturation. COCs were matured in different media: Medium 199 (M199 group), M199 with 100 μM CLA (M199 + CLA group), SOF (SOF group), and SOF with 100 μM CLA (SOF + CLA group). COCs matured with SOF showed a higher relative abundance of mRNA of quality indicators gremlin 1 ( GREM1 ) and prostaglandin-endoperoxide synthase 2 ( PTGS2 ) in oocytes, and GREM1 in cumulus cells compared with in the M199 group. SOF medium COCs had a higher relative abundance of fatty acid desaturase 2 ( FADS2 ) compared with the M199 group, which is essential for lipid metabolism in oocytes. Furthermore, the abundance of stearoyl-coenzyme A desaturase 1 ( SCD1 ) in oocytes matured with SOF was not influenced by the addition of CLA, whereas the relative abundance of SCD1 was reduced in M199 medium with CLA. We concluded that maturation in SOF medium results in a greater abundance of genes linked to quality and lipidic metabolism in oocytes, regardless of the addition of CLA.

Early embryonic mortality caused by maternal-fetal recognition failure in the three weeks after fertilization represents a major cause of reproductive inefficiency in the cattle industry. Modifying the amounts and ratios of prostaglandin (PG) F 2α and PGE 2 can benefit the establishment of pregnancy in cattle. Adding conjugated linoleic acid (CLA) to endometrial and fetal cells culture affects PG synthesis, but its effect on bovine trophoblast cells (CT-1) is unknown. The aim of this study was to determine the effects of CLA (a mixture of cis- and trans-9, 11- and -10,12-octadecadienoic acids) on PGE 2 and PGF 2α synthesis and the expression of transcripts involved with maternal-fetal recognition of bovine trophectoderm. Cultures of CT-1 were exposed to CLA for 24, 48 and 72 h. Transcript abundance was determined by qRT-PCR and hormone profiles were quantified by ELISA. The PGE 2 and PGF 2α concentrations were reduced in the culture medium of CLA-exposed CT-1 compared to that of unexposed cells. Furthermore, CLA supplementation increased the PGE 2 :PGF 2α ratio in CT-1 and had a quadratic effect (P < 0.05) on the relative expression of MMP9, PTGES2, and PTGER4. The relative expression levels of PTGER4 were reduced (P < 0.05) in CT-1 cultured with 100 μM CLA than in the unsupplemented and 10 μM-CLA groups. Treatment of CT-1 with CLA decreased PGE 2 and PGF 2α synthesis but a biphasic effect of CLA was observed on the PGE 2 :PGF 2α ratio and relative abundance of transcripts with 10 μM CLA providing maximal improvements in each endpoint. Our data suggest that CLA may influence eicosanoid metabolic process and extracellular matrix remodeling., Competing Interests: Declaration of competing interest The authors have declared that no competing interests exist., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In cattle, 17β-estradiol (E2) stimulates prostaglandin F2α (PGF2α) synthesis, which causes luteolysis. Except for the well-established upregulation of oxytocin receptor gene (OXTR), molecular mechanisms of E2-induced PGF2α release in vivo remain unknown. We hypothesized that E2-induced PGF2α release requires de novo transcription of components of the PGF2α synthesis machinery. Beef cows (n = 52) were assigned to remain untreated (Control; n = 10), to receive 50% ethanol infusion intravenously (Placebo; n = 21), or 3 mg E2 in 50% ethanol infusion intravenously (Estradiol; n = 21) on day 15 (D15) after estrus. We collected a single endometrial biopsy per animal at the time of the treatment (0h; Control B0h group), 4 hours (4h; Placebo B4h group and Estradiol B4h group), or 7 hours (7h; Placebo B7h group and Estradiol B7h group) post-treatment. Compared to the Placebo group, the Estradiol group presented significantly greater 13,14-dihydro-15-keto-PGF2α concentrations between 4h and 7h and underwent earlier luteolysis. At 4h, the qPCR analysis showed a lower abundance of ESR1, ESR2 and aldo-keto reductase family 1 member B1 (AKR1B1) genes in the Estradiol B4h group, and a greater abundance of OXTR compared to the Placebo B4h group. Similarly, the E2 treatment significantly reduced the abundance of AKR1B1, and AKR1C4 in the Estradiol B7h group, compared to the placebo group. Overall, E2-induced PGF2α release and luteolysis involved an unexpected and transient downregulation of components of the PGF2α-synthesis cascade, except for OXTR, which was upregulated. Collectively, our data suggest that E2 connects newly-synthesized OXTR to pre-existing cellular machinery to synthesize PGF2α and cause luteal regression., (Copyright © 2021. Published by Elsevier Inc.)

In the present study, there was an evaluation of in vitro embryo production (IVEP) in Bos indicus donor cows with small or large antral follicle counts (AFCs) when there was synchronization of follicular dynamics among cows before ovum pick-up (OPU). Donor cows classified as having small or large AFC were submitted to OPU/IVEP program (Experiment-I) or had follicular-stage synchronization imposed before OPU/IVEP (Experiment-II). In Experiment-I, the cows with a large AFC had a greater (P < 0.01) mean of embryos developing to the blastocyst stage compared to those with a small AFC. In Experiment-II, percentage of viable oocytes/OPU were not affected (P = 0.33) by synchronization of follicular dynamics, but the AFC had an effect (P < 0.0001). There was an interaction (P = 0.01) indicating the larger AFC, with or without imposing of a synchronization treatment regimen, resulted in the most desirable outcome. The number of embryos was affected (P < 0.001) by follicular-stage synchronization and AFC, with there being an interaction (P = 0.002) with the most desirable results for the large AFC-synchronized group. Number of pregnancies was greater (P ≤ 0.02) for recipient females with embryos from synchronized donors and with a large AFC. There was an interaction (P = 0.03) with there being a greater pregnancy percentage for cows with synchronized follicular stages and the large AFC. Bos indicus donor with a large AFC when associated with the synchronization of stage of follicular dynamics pre-OPU results in improvement of the efficacy of IVEP., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In cattle, the oviduct is a tubular organ that connects the ovary and the uterus. The oviduct lumen stages a dynamic set of cellular and molecular interactions to fulfill the noble role of generating a new individual. Specific anatomical niches along the oviduct lumen provide the appropriate microenvironment for final sperm capacitation, oocyte capture and fertilization, and early embryo development and transport. To accomplish such complex tasks, the oviduct undergoes spatially and temporally-regulated morphological, biochemical, and physiological changes that are associated with endocrine events of the estrous cycle. Specifically, elevated periovulatory concentrations of estradiol (E2) and progesterone (P4) influence gene expression and morphological changes that have been associated positively to fertility in beef cattle. In this review, we explore how E2 and P4 influence oviductal function in the beginning of the estrous cycle, and prepare the oviductal lumen for interactions with gametes and embryos., Competing Interests: The authors declare there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported in this article.

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n=15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P<0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P<0.05) and phospholipase A2 was downregulated (P<0.05) in endometrium of the LF-LCL group. No difference (P>0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P<0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.