Nitric oxide increases endocervical secretion at the ovulatory phase in the female

Uterine cervical mucus is crucial for reproduction, facilitating sperm transport and survival in certain mammals. Cholinergic autonomic nervous secretory innervation has been established, and modulation of secretion by prostaglandins and non-steroidal anti-inflammatory drugs has been postulated. It has been suggested that glandular nitric oxide (NO) production is a prerequisite for the autonomic cholinergic nervous modulation of cervical, endometrial, and the seminal vesicle secretion in the guinea pig. Most secretory genital tract cells, female as well as male, seem to display NO synthase activity.

Cervical secretion at ovulation time was studied in 10 women with regular menstruation. In an in vivo model with repeated collection of mucus samples during four 60-min periods, the amount of mucus was estimated in a control experimental series and in an experimental series following sublingual administration of the NO donor nitroglycerin.

This nitroglycerin administration markedly increased cervical secretion, while no changes in cervical secretion were seen in the control experimental series.

The results suggest that glandular NO production increases cervical secretion. Thus, cervical secretion may, apart from hormonal regulation, be influenced by the autonomic nervous system, and in addition, NO may be a prerequisite for this influence. This in turn may have implications on fertilization and fertility regulation.