Localization and expression of gastrin-releasing peptide (GRP) in the bovine cervix

Gastrin-releasing peptide (GRP) has been suggested as a novel regulatory peptide in the female reproductive tract but the presence of GRP and GRP mRNA in the non-neurogenic tissue of the cervix has not yet been clarified. In the present study, immunohistochemistry and in situ hybridization were used to reveal the distribution of GRP immunoreactivity and expression of GRP mRNA in the bovine cervix. The cervixes from 21 non-pregnant and 20 pregnant cows, and 6 fetuses were used in the study. In the fetus, adult non-pregnant and pregnant specimens, GRP and GRP mRNA were predominantly detected in the luminal epithelial cells of basal areas of peripheral regions of the cervix. Positive staining of GRP in the epithelial cells of the cervix was first detected in the CRL 37 cm of the fetus. During the estrous cycles, the staining intensity of GRP in the epithelial cells was stronger in the follicular phase than in the luteal phase. During the early gestational period, GRP immunoreactivity was detected at relatively similar intensity to the follicular phase. In situ hybridization results ascertained the expression of GRP mRNA in the superficial epithelial cells of the cervix of non-pregnant and pregnant cows. The results suggest that GRP may be important both in the development of the fetal cervix and secretory activity of the epithelial cells of the cervix.