Objective: To measure cystic fibrosis transmembrane regulator (CFTR) gene expression in cervical secretions during the menstrual cycle.
Design: Prospective, descriptive clinical study.
Patients: Thirteen healthy women with ovulatory menstrual cycles.
Interventions: Endocervical cells and secretions were obtained by cytobrushings during the midfollicular, midcycle, and luteal phases. The cells were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) for CFTR and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression.
Main outcome measures: Detection of CFTR gene expression and a quantitative comparison of the levels of CFTR to GAPDH gene expression.
Results: All endocervical samples exhibited some degree of CFTR gene expression throughout the menstrual cycle; however, the levels of expression were variable. Cystic fibrosis transmembrane regulator gene expression did not correlate with E2 or P levels.
Conclusion: The production of copious cervical secretions at the time of ovulation in part may be because of the transport of sodium and water across endocervical cell membranes as a result of E2-stimulated CFTR mRNA and protein. Although cervical mucus becomes thick and scant during the luteal phase, CFTR gene expression is present in these secretions.