Tyrosine kinase B receptor and its activated neurotrophins in ovaries from human fetuses and adults

• Published in: Molecular human reproduction 2006-06, Vol.12 (6), p.357-365
• Main Authors: Harel, S., Jin, S., Fisch, B., Feldberg, D., Krissi, H., Felz, C., Freimann, S., Tan, S.L., Ao, A., Abir, R.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biological and medical sciences; Brain-Derived Neurotrophic Factor - analysis; Brain-Derived Neurotrophic Factor - genetics; Embryology: invertebrates and vertebrates. Teratology; Female; Fetus; Fundamental and applied biological sciences. Psychology; Humans; Immunohistochemistry; Nerve Growth Factors - analysis; Nerve Growth Factors - genetics; neurotrophins; Ovarian Follicle - chemistry; Ovarian Follicle - cytology; Ovarian Follicle - metabolism; Ovary - chemistry; Ovary - cytology; Ovary - metabolism; primordial follicles; Receptor, trkB - analysis; Receptor, trkB - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; RT–PCR; TrkB receptor
• ISSN: 1360-9947; 1460-2407
• DOI: 10.1093/molehr/gal033

The signals initiating the growth of primordial follicles are unknown. Growth factors such as neurotrophin 4/5 (NT-4/5) and brain-derived neurotrophic factor (BDNF) may play a role in this process. To investigate the expression of NT-4/5 and BDNF and their receptor tyrosine kinase B (TrkB) in the early developing follicles, we fixed and froze 12 ovarian samples from adolescents/adults and 31 ovaries from human fetuses. The fixed samples were prepared for immunohistochemical staining for NT-4/5, BDNF and the TrkB receptor. Total RNA was extracted from the frozen ovarian samples, and the expression of NT-4/5, BDNF and the TrkB receptor (full length and two truncated isoforms) was investigated by RT–PCR. Products were resolved by 1% agarose gel electrophoresis and image analysis. Immunohistochemical staining revealed the expression of NT-4/5 and BDNF mainly in oocytes and, in a minority of samples, also in the granulosa cells (GCs); TrkB receptor was identified in oocytes and GCs. Transcripts of NT-4/5, BDNF and all forms of TrkB receptor were identified in the samples. To elucidate whether indeed NT-4/5 and BDNF are involved in growth initiation of human primordial follicles, they should be added to the culture medium.