Presence of NGF and its receptors in ovaries from human fetuses and adults

Abstract

The ability to mature human primordial follicles in vitro would assist fertility restoration. However, the signals initiating growth of primordial follicles are unknown. Growth factors such as nerve growth factor (NGF) may play a role in this process. To investigate the expression of NGF and its receptors, p75 and TrkA, in early developing follicles (mostly primordial, primary and secondary follicles), ten ovarian samples from adolescents/adults aged 13-39 and 33 ovaries from human fetuses aged 19-33 gestational weeks (GW) were obtained and immediately fixed or frozen. The fixed samples were prepared for a study of immunocytochemical staining of NGF and its two receptors. Total RNA was extracted from the frozen ovarian samples, and the expression of NGF, TrkA and p75 was investigated by RT-PCR. Products were resolved by 1% agarose gel electrophoresis and image analysis. Immunocytochemical staining revealed the expression of NGF in granulosa cells (GC) and oocytes; TrkA was mainly in oocytes and in GC in minority of the samples; and p75 was in some of the stroma cells from fetuses aged less than 22 GW. Transcripts of NGF and TrkA were identified by RT-PCR in all samples, while those for p75 were detected only in ovarian samples from fetuses aged less than 22 GW. To elucidate if NGF is indeed involved in growth initiation of human primordial follicles, it should be added to their culture medium. The immunocytochemical detection of p75 in some of the stroma cells and transcripts in ovarian samples of fetuses less than 22 GW may suggest its role in follicular assembly.

Expression of Nerve Growth Factor and Its Receptors, TrkA and p75, in Porcine Ovaries

“…The distribution of NGF and its two receptors in oocytes observed in the present study matched those in golden hamsters [16] and Shiba goats [21]. NGF and TrkA are also expressed by human oocytes in early developing [35] and preovulatory [34] follicles. Moreover, TrkA and/or p75 have been found in porcine and bovine [18] as well as mouse [24] oocytes.…”

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

“…During the oestrous cycle of the golden hamster, NGF, NTRK1 and NGFR were reported to localize to oocytes, granulosa cells and theca cells of follicles representing various stages of folliculogenesis and their presence was also detected in interstitial and luteal cells (Shi et al 2004). In humans, NGF was present in normally cycling women , and it has also been quantified in the follicular fluid of women undergoing IVF and ovulation induction for fertility (Abir et al 2005). NGF and NTRK1 were also detected in human preantral and antral follicle-derived granulosa cells and in theca cells of antral follicles (Salas et al 2006).…”

Immunolocalization of NGF and Its Receptors trkA and p75 in the Oviducts of Golden Hamsters during the Estrous Cycle

“…Furthermore, the effect of NGF is also mediated via the low affinity p75 receptor and other neurotropin receptors [5]. Evidence has accumulated that NGF and its receptors play a critical role in the development of the mammalian ovary, oogenesis, and folliculogensis [1,6,7,16,21]. In our previous studies, -Note-the presence of NGF and its two receptors, trkA and p75, was demonstrated in the reproductive organs, demonstrating that NGF and its receptors, trkA and p75, have important autocrine and paracrine regulatory roles in gonadal function [11,15,21,22].…”