Brain nitric oxide synthase expression is enhanced in the human cervix in labor.

OBJECTIVES

To determine whether brain nitric oxide synthase (bNOS) is expressed in human cervix, define its localization, and examine the possibility that it contributes to the nitric oxide (NO) pool and has a role in human cervical ripening.

METHODS

Human cervical biopsy tissues were collected from four groups: (1) nonpregnant patients, (2) term nonlabor (cesarean delivery) patients, (3) term labor patients with cesarean deliveries, and (4) term labor patients (vaginal delivery). The mRNA expression was assessed using reverse-transcribed polymerase chain reaction and in situ hybridization. The protein expression was determined using Western blot and its localization was shown using immunostaining.

RESULTS

Both bNOS mRNA and protein are present in human cervical tissue. They were localized to stroma cells and epithelial cells by in situ hybridization and immunostaining. bNOS protein expression in the labor group was significantly higher than in the nonlabor group (P <.05).

CONCLUSION

bNOS is expressed in the human cervix and enhanced expression is observed in labor, suggesting its possible role in contributing to the NO pool in the human cervix, in cervical ripening, and in labor.