Expression of neurotrophin 3 and its tropomyosin-related kinase receptor C in human preantral follicles

Objective: To investigate the expression of neurotrophin 3 (NT3) and its receptor tropomyosin-related kinase C (TrkC) in human preantral follicles. Neurotrophins appear to play important roles in preantral follicles. Data on ovarian NT3 and its receptor TrkC are sparse in humans. Design: Immunohistochemical, in situ hybridization, and reverse transcriptase polymerase chain reaction study of the expression of the NT3 system in human ovaries. Setting: Major tertiary-care academic center. Patient(s): Fifteen patients who underwent pregnancy terminations and 36 girls and women who underwent laparoscopies for ovarian surgery. Intervention(s): None. Main Outcome Measure(s): Laboratory analysis of human ovaries. Result(s): NT3 protein staining was identified in oocytes and granulosa cells (GCs) of all samples tested. TrkC protein staining was present in oocytes and GCs of the majority of the fetal samples and in oocytes and GCs of all samples from girls and women. The messenger RNA transcripts for the full-length TrkC isoform were identified in oocytes of the majority of the fetal samples, in all the samples from the girls and women, and in GCs from the girls and women. The two NT3 isoforms and the three TrkC isoforms were identified by reverse transcription polymerase chain reaction in all ovarian extracts. Conclusion(s): The presence of NT3 and its TrkC receptor in human preantral follicles, and specifically in GCs, suggests that NT3 may be involved in early folliculogenesis, particularly in the activation of primordial follicles.