The roles of glial cell line-derived neurotrophic factor, brain-derived neurotrophic factor and nerve growth factor during the final stage of folliculogenesis: a focus on oocyte maturation.

Neurotrophic factors were first identified to promote the growth, survival or differentiation of neurons and have also been associated with the early stages of ovarian folliculogenesis. More recently, their effects on the final stage of follicular development, including oocyte maturation and early embryonic development, have been reported. Glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), which are expressed in numerous peripheral tissues outside of the CNS, most notably the ovary, are now known to stimulate oocyte maturation in various species, also enhancing developmental competence. The mechanisms that underlie their actions in antral follicles, as well as the targets ultimately controlled by these factors, are beginning to emerge. GDNF, BDNF and NGF, alone or in combination, could be added to the media currently utilized for in vitro oocyte maturation, thereby potentially increasing the production and/or quality of early embryos.