Neurotrophins (BDNF and NGF) in follicular fluid of women with different infertility diagnoses

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are intra-ovarian signalling peptides that are important in follicle development and oocyte maturation. In the ovary, neurotrophin expression is regulated by gonadotrophins. Therefore, this study postulates that aetiology of infertility will affect follicular-fluid BDNF and NGF concentrations. Follicular fluid from the first follicle aspirated from 190 infertile women attending a university-affiliated fertility programme (McMaster University and ONE Fertility, Burlington, Ontario) was collected between February 2004 and November 2010. The relationship between follicular-fluid BDNF and NGF concentration and age, day-3 FSH and peak serum oestradiol concentrations and antral follicle count was determined. Participants were aged between 24 and 44 years (mean ± SEM, 35.2 ± 0.3 years) of age. The median concentrations of BDNF and NGF in the follicular fluid was 19.4 pg/ml and 344.6 ng/ml, respectively. The concentrations of BDNF and NGF were significantly related (P = 0.028) but only the BDNF concentration was significantly higher (P < 0.05) in women with unexplained infertility compared with other causes of infertility. It is concluded that, apart from unexplained infertility, the underlying cause of infertility did not affect ovarian output of BDNF and NGF in response to ovulation induction.Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are proteins that are produced in the brain, where they play a role in the development and survival of brain cells. Emerging evidence has shown that these proteins are also made in the ovary, where they are thought to be important in the recruitment and development of a woman’s oocytes (eggs). In the ovary, the hormones responsible for controlling the production of female hormones, such as oestradiol, are believed to also regulate the production of BDNF and NGF. Therefore, we proposed that the concentrations of these proteins in the fluid surrounding the developing egg (follicular fluid) could be affected by the underlying causes of infertility. Therefore we measured the concentration of these proteins in the follicular fluid collected from 190 infertile women attending a university-affiliated fertility programme (McMaster University and ONE Fertility, Burlington, Ontario). In this study, the concentrations of BDNF and NGF were significantly related but only the BDNF concentration was significantly higher in women with unexplained infertility compared with other causes of infertility. We conclude that, apart from unexplained infertility, the underlying cause of infertility did not affect ovarian output of these proteins.