The cystic fibrosis transmembrane regulator gene is expressed in the human endocervix throughout the menstrual cycle.

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.