Now showing 1 - 2 of 2
  • Publication
    Changes in the endometrial transcriptome during the bovine estrous cycle: effect of low circulating progesterone and consequences for conceptus elongation
    In cattle, elevated concentrations of circulating progesterone (P4) in the immediate post-conception period have been associated with an advancement of conceptus elongation, an associated increase in interferon-tau production and higher pregnancy rates. Low P4 has been implicated as a causative factor in the low pregnancy rates observed in dairy cows. The aims of this study were (1) to describe the changes that occur in the bovine endometrial transcriptome during the estrous cycle, (2) to determine how elevated P4 affects the temporal pattern of gene expression in the endometrium of cyclic heifers, (3) to determine if the expression of these genes is altered in heifers with low P4 and (4) to determine the consequences of low P4 for conceptus development following embryo transfer. The main findings were that 1) relatively few differences occurred in endometrial gene expression during the early luteal phase of the estrous cycle under normal concentrations of P4 (Day 5 versus Day 7) but comparison of endometria from more distant stages of the luteal phase (Day 7 versus Day 13) revealed large transcriptional changes; 2) exogenous supplementation of P4, leading to elevated concentrations from Day 3 to Day 8, considerably altered the expression of a large number of genes at all stages of the luteal phase; 3) induction of low circulating P4 altered the normal temporal changes that occured in the expression of these genes, mainly by delaying their expression; 4) this delay in gene expression was, in part, due to delayed down regulation of the PGR from the LE and GE, and 5) the altered endometrial gene expression induced by low P4 was associated with a reduced capacity of the uterus to support conceptus development after embryo transfer on Day 7. In conclusion, the present study provides clear evidence for a temporal change in the transcriptomic signature of the bovine endometrium which is sensitive to the concentrations of circulating P4 in the first few days after estrus and which can, under conditions of low progesterone, lead to an suboptimal uterine environment and a reduced ability to support conceptus elongation.
      416Scopus© Citations 209
  • Publication
    Hormonal composition of follicular fluid from abnormal follicular structures in mares
    The objective was to characterise the hormonal composition of follicular fluid from mares with distinct anovulatory-cystic follicles. Follicular fluid was aspirated from six mares that presented with cystic follicles and from pre-ovulatory follicles of five normal mares (controls). Differences in progesterone, oestradiol, testosterone, IGF-I and IGF binding were analysed using Fisher's exact test. There were greater (P<0.03) follicular fluid oestradiol concentrations in normal follicles and the testosterone concentration of the cystic fluid was greater (P<0.05) than that of the normal fluid. There also was a greater (P<0.03) percentage of IGF-I binding and lower (P<0.02) IGF-I concentrations in the fluid collected from the cystic structures compared with the fluid from normal follicles. Despite the limited number of animals, the fact that fluid aspirated from cystic follicles had higher testosterone and lower oestradiol concentrations could be of diagnostic value when a practitioner wants to distinguish between a cystic and non-cystic persistent follicle. The research reported here also indicates a likely role for the IGF system in the pathogenesis of the development and maintenance of anovulatory follicular structures in mare ovaries.
      475Scopus© Citations 3