Tyrosine kinase B receptor and its activated neurotrophins in ovaries from human fetuses and adults.
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.
Harel
S
S
Infertility and IVF UnitHelen Schneider's Women Hospital, Rabin Medical Center, Petach Tikva and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Jin
S
S
Fisch
B
B
Feldberg
D
D
Krissi
H
H
Felz
C
C
Freimann
S
S
Tan
S L
SL
Ao
A
A
Abir
R
R
D000293:Adolescent; D000328:Adult; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis / Q000235:genetics; D005260:Female; D005333:Fetus; D006801:Humans; D007150:Immunohistochemistry; D009414:Nerve Growth Factors / Q000032:analysis* / Q000235:genetics; D006080:Ovarian Follicle / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D010053:Ovary / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020813:Receptor, trkB / Q000032:analysis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D012333:RNA, Messenger; C071951:neurotrophin 5; D020813:Receptor, trkB; C073922:neurotrophin 4