Lethal effect of high concentrations of Parecoxib and Flunixin meglumine on the in vitro culture of bovine embryos

Since cyclooxygenase (COX) inhibitors have been pointed out as potent ial treatments to increase pregnancy rates after embryo transfer, the present experiment aimed to evaluate the effects of flunixin meglumine (FM) and parecoxib (P), a COX-1 and 2 or COX-2 specific inhibitor, respectively, on the development of bovine embryos until the hatched blastocyst stage. In vitro produced bovine embryos were cultured in media with different concentrations of FM (0.14; 1.4; 14; 140 or 1400 μg/ml) or P (0.09; 0.9; 9; 90 or 900 μg/ml) and the production rates were evaluated. Concentrations of FM ≤ 14 μg/ml and P ≤ 90 μg/ml did not impair embryo development, although compiled data from non-lethal FM concentrations ( ≤ 14 μg/ml) indicated a toxic effect enough to decrease the hatching rate of blastocysts. Concentrations of FM at 140 and 1400 μg/ml and P at 900 μg/ml were lethal as no cleavage was detected on presumptive zygotes.

Lethal effect of high concentrations of Parecoxib and Flunixin meglumine on the in vitro culture of bovine embryos

Since cyclooxygenase (COX) inhibitors have been pointed out as potent ial treatments to increase pregnancy rates after embryo transfer, the present experiment aimed to evaluate the effects of flunixin meglumine (FM) and parecoxib (P), a COX-1 and 2 or COX-2 specific inhibitor, respectively, on the development of bovine embryos until the hatched blastocyst stage. In vitro produced bovine embryos were cultured in media with different concentrations of FM (0.14; 1.4; 14; 140 or 1400 μg/ml) or P (0.09; 0.9; 9; 90 or 900 μg/ml) and the production rates were evaluated. Concentrations of FM ≤ 14 μg/ml and P ≤ 90 μg/ml did not impair embryo development, although compiled data from non-lethal FM concentrations ( ≤ 14 μg/ml) indicated a toxic effect enough to decrease the hatching rate of blastocysts. Concentrations of FM at 140 and 1400 μg/ml and P at 900 μg/ml were lethal as no cleavage was detected on presumptive zygotes.(AU)

Luteinizing Hormone Receptor (LHR): basic concepts in cattle and other mammals. A review

Acquisition of the luteinizing hormone receptor (LHR) on granulosa cells of the dominant follicle is essential to physiological LH-mediated effects on the final stages of follicular growth, final maturation of the oocyte, ovulation and luteinization of the follicular wall.Therefore, LHR plays a key role in the final maturation of the dominant follicle from follicular dominance to ovulation. In this review, the basic molecular aspects of LHR (gene structure, alternative splicing and ligand mediated activation) and the physiological regulatory aspects (changes in LHR expression during antral follicle growth and a post-transcriptional model for downregulation of LHR transcripts) are addressed. Despite the accumulation of considerable amounts of information about LHR, a comprehensive and broad model for the role of LHR in bovine antral follicle growth is missing. Questions such as the function for alternative LHR transcripts, their transcriptional and translational regulation, and how the transcripts go to the cell surface and interact with ligands remain to be elucidated in bovine and other species.(AU)

Luteinizing Hormone Receptor (LHR): basic concepts in cattle and other mammals. A review

Acquisition of the luteinizing hormone receptor (LHR) on granulosa cells of the dominant follicle is essential to physiological LH-mediated effects on the final stages of follicular growth, final maturation of the oocyte, ovulation and luteinization of the follicular wall.Therefore, LHR plays a key role in the final maturation of the dominant follicle from follicular dominance to ovulation. In this review, the basic molecular aspects of LHR (gene structure, alternative splicing and ligand mediated activation) and the physiological regulatory aspects (changes in LHR expression during antral follicle growth and a post-transcriptional model for downregulation of LHR transcripts) are addressed. Despite the accumulation of considerable amounts of information about LHR, a comprehensive and broad model for the role of LHR in bovine antral follicle growth is missing. Questions such as the function for alternative LHR transcripts, their transcriptional and translational regulation, and how the transcripts go to the cell surface and interact with ligands remain to be elucidated in bovine and other species.

Use of LH or eCG in the last day of superestimulatory treatment

In the last decades several hormonal treatments to induce multiple ovulation and embryo transfer (MOET) have been developed. Tight control of the time of ovulation allowed the use of fixed-time artificial insemination (FTAI) in embryos donors, facilitating animal management. Although, protocols that allow FTAI have evolved and yield as much embryo as conventional protocols that requires estrus detection, substantial increase in viable embryo production has not been observed in superestimulated bovine cattle. The present mini-review put emphasis on superstimulatory protocols in which the last two doses of pFSH are replaced by eCG or LH. Recent results indicate that an extra LH stimulus (using eCG or LH), on the last day of P-36 superestimulatory treatment, seems to improve transferable embryo yield in both Bos taurus and Bos indicus cattle.