Peri-ovulatory endocrine regulation of the prostanoid pathways in the bovine uterus at early dioestrus.

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.

Supplementation with sunflower seed increases circulating cholesterol concentrations and potentially impacts on the pregnancy rates in Bos indicus beef cattle.

We aimed to evaluate the effect of supplementation with sunflower seed on blood concentrations of progesterone and cholesterol and on the pregnancy rate in beef cattle subjected to timed artificial insemination (TAI) and timed embryo transfer (TET). In experiment 1, cows were received 22-day supplements containing (sunflower, n = 66) sunflower seed or not (control, n = 67) immediately after a progesterone/estradiol-based TAI protocol (Day 0). The cholesterol concentration on Day 21 and the pregnancy rate were greater (P < 0.03) in the sunflower group (148.2 ± 6.1 mg/dL and 66.7%) than those in the control group (116.0 ± 6.4 mg/dL and 47.8%). In experiment 2, heifers received an in vitro-produced embryo 7 days after the expected time of the synchronized ovulation. Heifers were separated into two supplementation groups (sunflower, n = 106 and control, n = 111) for 22 days. The plasma progesterone concentration on Day 7 was not different between the groups. However, on Day 19, the plasma progesterone concentration was greater (P < 0.0001) in the sunflower group (5.8 ± 0.4 ng/mL) than that in the control group (3.5 ± 0.4 ng/mL). A greater (P < 0.05) cholesterol concentration was observed in the sunflower group than that in the control group on Days 7 (306.0 ± 11.6 vs. 277.1 ± 11.9 mg/dL, respectively) and 19 (260.5 ± 8.0 vs. 232.0 ± 8.0 mg/dL, respectively). The pregnancy rate was greater (P = 0.01) in the sunflower-treated heifers (55.7%) than that in control-treated heifers (36.9%). Results indicate that sunflower seed supplementation increases the circulating cholesterol concentrations and potentially impacts the pregnancy rate in suckled beef cattle subjected to TAI or TET.

Spatio-specific regulation of endocrine-responsive gene transcription by periovulatory endocrine profiles in the bovine reproductive tract.

In cattle, pro-oestrous oestradiol and dioestrous progesterone concentrations modulate endometrial gene expression and fertility. The aim was to compare the effects of different periovulatory endocrine profiles on the expression of progesterone receptor (PGR), oestrogen receptor 2 (ESR2), oxytocin receptor (OXTR), member C4 of aldo-keto reductase family 1 (AKR1C4), lipoprotein lipase (LPL), solute carrier family 2, member 1 (SLC2A1) and serpin peptidase inhibitor, clade A member 14 (SERPINA14): (1) between uterine horns ipsi- and contralateral to the corpus luteum (CL), (2) between regions of the ipsilateral horn and (3) in the vagina. Endometrium and vagina tissue samples were collected from cows that ovulated a larger (large follicle-large CL, LF-LCL; n=6) or smaller follicle (small follicle-small CL, SF-SCL; n=6) 7 days after oestrus. Cows in the LF-LCL group had a greater abundance of transcripts encoding ESR2, AKR1C4, LPL, SLC2A1 and SERPINA14, but a reduced expression of PGR and OXTR in the endometrium versus the SF-SCL group (PPGR and OXTR was greater in the contralateral compared with the ipsilateral horn (PPGR, ESR2, LPL, SLC2A1 and SERPINA14 (P<0.05). Different periovulatory endocrine profiles, i.e. LF-LCL or SF-SCL, did not influence gene expression in the vagina and had no interaction with inter- or intra-uterine horn gene expression. In conclusion, inter- and intra-uterine horn variations in gene expression indicate that the expression of specific genes in the bovine reproductive tract is location dependent. However, spatial distribution of transcripts was not influenced by distinct periovulatory sex-steroid environments.