Netrin-1: Just an axon-guidance factor?

Netrin-1 was first identified as a guidance factor in axon outgrowth during central nervous system development and was later shown to be involved in the morphogenesis of other organs. This study, thus, aimed to verify netrin-1 gene expression in swine antral follicles and to detect netrin-1 protein expression in follicular fluid. In addition, since netrin-1 is also a potential guidance factor for endothelial cells during angiogenesis, an essential event for follicular development, we attempted to verify its effects on swine aortic endothelial cells. Our results show that netrin-1 is present in follicular fluid and is physiologically expressed in both the thecal and granulosa layers from swine antral follicles. Furthermore, by means of an angiogenesis bioassay, we documented the inhibition of vascular neoformation by netrin-1. In conclusion, our results demonstrate that netrin-1 can be synthesized by swine follicular cells and secreted in the follicular fluid where it appears to exert regulatory effects on both follicular function and vascular development.