The axonal guidance factor netrin-1 as a potential modulator of swine follicular function

This study was aimed to improve knowledge about swine ovarian follicular function, paying attention to angiogenesis, since new vessel growth is a fundamental event in ovarian function. In particular, we investigated a potential involvement of netrin-1, a protein known as a guidance axon factor.Firstly, we studied the expression and immunolocalization of netrin-1 in swine ovarian follicle and its effect on cultured swine granulosa cell viability and steroidogenesis. Furthermore, aortic endothelial cells were employed to verify a possible netrin-1 effect on angiogenesis.Our data demonstrate the expression and the presence of netrin-1 in swine follicular fluid; in addition, it was shown that netrin-1 inhibits granulosa cell viability and estradiol 17β levels while it stimulates progesterone production. Netrin-1 also inhibits aortic endothelial cell growth in the angiogenesis bioassay. This effect appears to be mediated by inhibiting vascular endothelial growth factor and stimulating nitric oxide.Therefore, we hypothesize that netrin-1 could be important for follicular function in the swine.