VEGFA165 can rescue excess steroid secretion, inflammatory markers, and follicle arrest in the ovarian cortex of High A4 cows†.

A population of cows with excess androstenedione (A4; High A4) in follicular fluid, with follicular arrest, granulosa cell dysfunction, and a 17% reduction in calving rate was previously identified. We hypothesized that excess A4 in the ovarian microenvironment caused the follicular arrest in High A4 cows and that vascular endothelial growth factor A would rescue the High A4 phenotype. In trial 1, prior to culture, High A4 ovarian cortex (n = 9) had greater numbers of early stage follicles (primordial) and fewer later-stage follicles compared to controls (n = 11). Culture for 7 days did not relieve this follicular arrest; instead, High A4 ovarian cortex had increased indicators of inflammation, anti-Mullerian hormone, and A4 secretion compared to controls. In trial 2, we tested if vascular endothelial growth factor A isoforms could rescue the High A4 phenotype. High A4 (n = 5) and control (n = 5) ovarian cortex was cultured with (1) PBS, (2) VEGFA165 (50 ng/mL), (3) VEGFA165B (50 ng/mL), or (4) VEGFA165 + VEGFA165B (50 ng/mL each) for 7 days. Follicular progression increased with VEGFA165 in High A4 cows with greater early primary, primary, and secondary follicles than controls. Similar to trial 1, High A4 ovarian cortex secreted greater concentrations of A4 and other steroids and had greater indicators of inflammation compared to controls. However, VEGFA165 rescued steroidogenesis, oxidative stress, and fibrosis. The VEGFA165 and VEGFA165b both reduced IL-13, INFα, and INFß secretion in High A4 cows to control levels. Thus, VEGFA165 may be a potential therapeutic to restore the ovarian steroidogenic microenvironment and may promote folliculogenesis.

Attainment and maintenance of pubertal cyclicity may predict reproductive longevity in beef heifers†.

We hypothesized the manner that heifers achieve puberty may indicate their future reproductive longevity. Heifers with discontinued or delayed cyclicity during puberty attainment may have irregular reproductive cycles, anovulation, and infertility in their first breeding season contributing to a shorter reproductive lifespan. Therefore, plasma progesterone (P4) was measured from weaning to breeding on 611 heifers born 2012-2017 and four pubertal classifications were identified: (1) Early; P4 ≥ 1 ng/ml < March 12 with continued cyclicity, (2) Typical; P4 ≥ 1 ng/ml ≥ March 12 with continued cyclicity, (3) Start-Stop; P4 ≥ 1 ng/ml but discontinued cyclicity, and (4) Non-Cycling; no P4 ≥ 1 ng/ml. Historical herd records indicated that 25% of heifers achieved puberty prior to March 12th in the 10 years prior to the study. Start-Stop and Non-Cycling yearling heifers were lighter indicating reduced growth and reproductive maturity traits compared with Early/Typical heifers. In addition, Non-Cycling/Start-Stop heifers were less responsive to prostaglandin F2 alpha (PGF2α) to initiate estrous behavior and ovulation to be artificially inseminated. Non-Cycling heifers had fewer reproductive tract score-5 and reduced numbers of calves born in the first 21-days-of-calving during their first breeding season. Within the Start-Stop classification, 50% of heifers reinitiated cyclicity with growth traits and reproductive parameters that were similar to heifers in the Early/Typical classification while those that remained non-cyclic were more similar to heifers in the Non-Cycling group. Thus, heifers with discontinued cyclicity or no cyclicity during puberty attainment had delayed reproductive maturity resulting in subfertility and potentially a shorter reproductive lifespan.

Bovine pregnancy associated glycoproteins can alter selected transcripts in bovine endometrial explants.

This study was designed to examine changes in target transcript abundance in endometrial explants exposed to pregnancy-associated glycoproteins (PAGs). Endometrial explants from pregnant and non-pregnant heifers collected on day18 (day 0: day of insemination) were incubated in the absence or presence of PAGs (15 µg/ml). The PAGs represented a mixture comprised of approximately equal amounts of bovine PAGs 4, 6, and 9. Samples were harvested for RNA extraction after 24 h or 96 h of incubation. Transcript abundance for target genes related to prostaglandin synthesis (PTGES), a chemokine (CXCL5) and tissue remodeling (EMMPRIN; MMPs 1, 2, 3, 7, 8, and 9; PLAU; SPP1; TIMP1 and TIMP2) were analyzed by quantitative PCR. Changes in relative transcript abundance for MMP1, MMP3, MMP7, PLAU, EMMPRIN and SPP1 were observed after PAG exposure in both non-pregnant and pregnant endometrium (P < 0.05). However, some of the transcripts associated with tissue remodeling were altered only at certain time points (either 24 h or 96 h). The transcript for bovine CXCL5 was increased in non-pregnant endometrium four- and six-fold at 24 h and 96 h of PAG exposure, respectively (P < 0.05); in pregnant endometrium, only the 24 h incubation period exhibited an elevation in CXCL5 (P < 0.05). In non-pregnant endometrium, both PTGES and MMP9 were elevated after exposure to PAGs for 24 h (P < 0.05) but not in the other samples. Some interferon-responsive transcripts (IFI6, ISG15) were found to be more abundant (P < 0.05) in pregnant endometrium after 96 h exposure to PAGs compared to endometrium that had not been exposed to the PAGs. Likewise, ISG15 message was elevated (P = 0.06) in non-pregnant endometrium after 24 h incubation with PAGs. These results indicate that the PAGs used in this experiment were able to induce changes in endometrial transcripts encoding for proteins associated with matrix remodeling as well as chemokine production and prostaglandin release.