Neutralization of vascular endothelial growth factor antiangiogenic isoforms or administration of proangiogenic isoforms stimulates vascular development in the rat testis

Vascular endothelial growth factor A (VEGFA) plays a role in both angiogenesis and seminiferous cord formation, and alternative splicing of the Vegfa gene produces both proangiogenic isoforms and antiangiogenic isoforms (B-isoforms). The objectives of this study were to evaluate the expression of pro- and antiangiogenic isoforms during testis development and to determine the role of VEGFA isoforms in testis morphogenesis. Quantitative RT-PCR determined that Vegfa_165b mRNA was most abundant between embryonic days 13.5 and 16 (E13.5 and 16; P \u3c 0.05). Compared with ovarian mRNA levels, Vegfa_120 was more abundant at E13–14 (P \u3c 0.05), Vegfa_164 was less abundant at E13 (P \u3c 0.05), and Vegfa_165b tended to be less abundant at E13 (P \u3c 0.09) in testes. Immunohistochemical staining localized antiangiogenic isoforms to subsets of germ cells at E14–16, and western blot analysis revealed similar protein levels for VEGFA_165B, VEGFA_189B, and VEGFA_206B at this time point. Treatment of E13 organ culture testes with VEGFA_120, VEGFA_164, and an antibody to antiangiogenic isoforms (anti-VEGFAxxxB) resulted in less organized and defined seminiferous cords compared with paired controls. In addition, 50 ng/ml VEGFA_120 and VEGFA_164 treatments increased vascular density in cultured testes by 60 and 48% respectively, and treatment with VEGFAxxxB antibody increased vascular density by 76% in testes (0.5 ng/ml) and 81% in ovaries (5 ng/ml) compared with controls (P \u3c 0.05). In conclusion, both pro- and antiangiogenic VEGFA isoforms are involved in the development of vasculature and seminiferous cords in rat testes, and differential expression of these isoforms may be important for normal gonadal development

Vascular Endothelial Growth Factor A (VEGFA) in Ovulatory Follicles

Granulosa cells express vascular endothelial growth factor A (VEGFA), and VEGFA mRNA levels increase as bovine follicles reach preovulatory status. To further evaluate the role of VEGFA isoforms in follicular development, cows were either synchronized with a modified Co- Synch protocol (CIDR) or treated with melengestrol acetate (MGA) with subsequent aspiration of the dominant follicles. Higher mRNA levels for the antiangiogenic isoform, VEGFA_164B, along with AMH and CARTPT in E2-inactive follicles suggest that these factors are markers for unhealthy, atretic follicles. In contrast, higher mRNA levels for the proangiogenic isoform, VEGFA_164, in E2-active follicles indicate that this isoform may help predict healthy ovulatory follicles

Oocyte mRNA and Follicle Androgen Levels Associated with Fertility

The environment that the oocyte develops in (follicle) and the mRNA that is produced (mRNA abundance) during development were examined. Androgen levels within the follicle were higher in heifers (≤ 2 years) that never established a pregnancy compared to cows that stayed in the herd at least 3 years and had at least one successful pregnancy. These high androgen levels were associated with increased abundance of several candidate mRNAs in the cumulus-oocyte complex (COC), which includes the oocyte and somatic cells immediately surrounding the oocyte, isolated from the dominant follicle. The data suggest that androgen levels represent a marker for oocyte quality which could be used to select for females to retain in the herd

Granulosa Cell Gene Expression is Altered in Follicles from Cows with Differing Reproductive Longevity

Heifers and cows that were culled from the herd due to failure to become pregnant were categorized into groups with low (\u3c 2 year), moderate (\u3e2 and \u3c 6 year) or high (≥ 6 year) fertility. Antral follicle counts were numerically lower in the low group and increased in the moderate- and high-fertility group. Granulosa cells from dominant follicles in moderate- and high-fertility cows had a greater ratio of Vascular Endothelial Growth Factor 164 (VEGF164) to VEGF164B compared to the low-fertility cows. Furthermore, there was more CARTPT in granulosa cells from subordinate follicles in moderate- and high-fertility cows than low. Gene expression is altered in granulosa cells from cows differing in fertility, suggesting these are candidate genes that may be used as markers to assist in determining reproductive longevity in beef cows