Effect of Vascular Endothelial Growth Factor 165a and 165b on Porcine Primordial Follicle Viability Invitro

Abstract

Understanding how oocyte morphogens regulate folliculogenesis and how their actions and interactions are integrated into the overall processes in physiology and pathophysiology of reproductive systems of mammals is an existing challenge. Growth of an oocyte in mammal starts with an avascular structure called a ‘primordial follicle’ and subsequent to ovulation this avascular structure transforms into a heavily vascular corpus luteum. This primordial follicle activation is a complex process and it is not yet completely understood. Vascular endothelial growth factor (VEGF) is well-known for its ability to regulate angiogenesis from the existing blood vessels. Studies on VEGF play a pivotal role in understanding the primordial follicle activation and progression of their growth. The objective of the current study was to determine the effect of VEGF165a and VEGF165b on porcine primordial follicle development invitro. VEGF165a is known to be a pro-angiogenic factor where VEGF165b is anti-angiogenic. The tissue samples were treated with VEGF165a and VEGF165b with 0ng/ml, 0.1, 1.0, 10.0 ng/ml and the day 0 (Negative control) sample was fixed in 10% neutral buffered formalin instantly. The preliminary data were obtained from short-term (72 hours) in vitro culture of porcine ovarian cortical stripes and tissues were incubated under 5% CO2 with the humidified atmospheric conditions at 37.50C. Out of three different dose regimes in VEGF165a treated tissues, 0.1ng/ml resulted in the highest viable follicle count (92.6%) while 1.0ng/ml and 10ng/ml had shown 65.3% and 24.8% viable follicle count, respectively. The highest VEGF165a concentration recorded the highest follicle degeneration. Among the VEGF165b treated tissues, 0.1ng/ml, 1.0ng/ml and 10.0ng/ml have shown 65.3%, 43.7%, 17.3% follicle viability respectively. As VEGF165b is an anti-angiogenic factor, it contributed to the increase follicular degeneration in all treatments. It showed a pattern of follicle degeneration where higher concentrations had accelerated the follicle degeneration. In conclusion it was evident that the lowest VEGF165a concentration (0.1ng/ml) improved the follicular viability, where 1 and 10ng/ml VEGF165a increased the follicular degeneration. Also VEGF165b has a negative effect on follicular viability in-vitro. In animal’s body both VEGF165a and VEGF165b coexist while showing equilibrium. It needs to be further investigated to find the ideal concentrations of VEGF165a and VEGF165b that promote cell viability in vitro